JP6829572B2 - Winding non-aqueous lithium storage element - Google Patents

Description

The present invention relates to a non-aqueous lithium storage element assembled by a winding method.

In recent years, from the viewpoint of effective use of energy aiming at conservation of the global environment and resource saving, power smoothing system or midnight power storage system for wind power generation, distributed power storage system for home use based on solar power generation technology, power storage for electric vehicles Systems and the like are attracting attention.
The first requirement for batteries used in these power storage systems is high energy density. Lithium-ion batteries are being energetically developed as promising candidates for high-energy density batteries that can meet such demands.
The second requirement is that the output characteristics are high. For example, in a combination of a high-efficiency engine and a power storage system (for example, a hybrid electric vehicle) or a combination of a fuel cell and a power storage system (for example, a fuel cell electric vehicle), high output discharge characteristics in the power storage system are required during acceleration. There is.

Currently, electric double layer capacitors, nickel-metal hydride batteries, and the like are being developed as high-power power storage devices.
Among the electric double layer capacitors, those using activated carbon for the electrodes have an output characteristic of about 0.5 to 1 kW / L. This electric double layer capacitor has high durability (cycle characteristics and high temperature storage characteristics), and has been considered to be the most suitable device in the field where high output is required. However, its energy density is only about 1 to 5 Wh / L. Therefore, it is necessary to further improve the energy density.

On the other hand, the nickel-metal hydride battery currently used in hybrid electric vehicles has a high output equivalent to that of an electric double layer capacitor and an energy density of about 160 Wh / L. However, research is being vigorously pursued to further increase its energy density and output and to improve its durability (particularly, stability at high temperatures).

In addition, research is underway to increase the output of lithium-ion batteries. For example, a lithium ion battery has been developed in which a high output exceeding 3 kW / L can be obtained at a discharge depth (a value indicating what percentage of the discharge capacity of the power storage element is discharged) of 50%. However, its energy density is 100 Wh / L or less, and it is designed to intentionally suppress the high energy density, which is the greatest feature of lithium-ion batteries. Moreover, its durability (cycle characteristics and high temperature storage characteristics) is inferior to that of electric double layer capacitors. Therefore, in order to have practical durability, it is used in a range where the discharge depth is narrower than the range of 0 to 100%. Since the capacity that can be actually used becomes smaller, research for further improving durability is being vigorously pursued.

As described above, there is a strong demand for practical application of a power storage element having high energy density, high output characteristics, and durability. However, each of the existing power storage elements described above has advantages and disadvantages. Therefore, a new power storage element that satisfies these technical requirements is required. As a promising candidate, a power storage element called a lithium ion capacitor has attracted attention and is being actively developed.
A lithium ion capacitor is a kind of power storage element (non-aqueous lithium type power storage element) that uses a non-aqueous electrolyte solution containing a lithium salt, and adsorbs anions similar to an electric double layer capacitor at about 3 V or higher at a positive electrode. -A power storage element that charges and discharges by a non-Faraday reaction by desorption and a Faraday reaction by the storage and release of lithium ions at the negative electrode, similar to a lithium ion battery.
To summarize the above-mentioned electrode materials and their characteristics, high output and high durability are achieved when a material such as activated carbon is used for the electrodes and charging / discharging is performed by adsorption / desorption (non-Faraday reaction) of ions on the surface of activated carbon. However, the energy density becomes low (for example, it is multiplied by 1). On the other hand, when an oxide or carbon material is used for the electrode and charging / discharging is performed by the Faraday reaction, the energy density becomes high (for example, 10 times that of the non-Faraday reaction using activated carbon), but the durability and output characteristics There is a problem in.

As a combination of these electrode materials, the electric double layer capacitor is characterized by using activated carbon (energy density 1 times) for the positive electrode and the negative electrode and charging / discharging both the positive electrode and the negative electrode by a non-Faraday reaction, and has high output and high durability. However, it is characterized by low energy density (1x positive electrode x 1x negative electrode = 1).

The lithium ion secondary battery is characterized by using a lithium transition metal oxide (energy density 10 times) for the positive electrode and a carbon material (energy density 10 times) for the negative electrode, and charging and discharging both the positive electrode and the negative electrode by a Faraday reaction. Although the energy density (positive electrode 10 times x negative electrode 10 times = 100), there are problems in output characteristics and durability. Further, in order to satisfy the high durability required for a hybrid electric vehicle or the like, the discharge depth must be limited, and the lithium ion secondary battery can use only 10 to 50% of its energy.

Lithium-ion capacitors use activated carbon (1x energy density) for the positive electrode and carbon material (10x energy density) for the negative electrode, and are characterized by performing charging and discharging by a non-Faraday reaction at the positive electrode and a Faraday reaction at the negative electrode. It is a new asymmetric capacitor that has the characteristics of a multi-layer capacitor and a lithium ion secondary battery. The feature is that it has high energy density (1x positive electrode x 10x negative electrode = 10) while having high output and high durability, and it is not necessary to limit the discharge depth unlike a lithium ion secondary battery. is there.

Examples of applications using lithium ion capacitors include electric storage for railways, construction machinery, and automobiles. In these applications, the capacitors used are required to have excellent energy density, high input / output characteristics, and durability against high load charge / discharge cycles.

As a countermeasure technique for such a demand, there is known a technique of treating a non-opposing portion of a negative electrode in a wound body in which an opposing positive electrode does not exist.
For example, there is known a technique for preventing permeation so that the electrolytic solution does not permeate into the non-opposing portion (Patent Document 1). This prevents lithium ions from diffusing into the non-opposing portion of the negative electrode due to diffusion from other parts of the negative electrode active material layer or wraparound from the positive electrode active material layer, and prevents a decrease in the capacity of the power storage element. it can.

There is also a technique of diffusing lithium into the negative electrode active material in the facing portion and the non-opposing portion to expand the active material layer. (Patent Document 2) This can reduce deformation of the current collector due to occlusion and release of lithium, and can improve the characteristics of the power storage element such as cycle characteristics for a long period of time.

However, in the technique of Patent Document 1, there is a concern that the film formed by the permeation prevention treatment deteriorates and separates during a long-term test such as a high load cycle test, floats as an impurity in the electrolytic solution, and becomes a resistance component. .. Further, the increase in the thickness and the volume of the non-opposing portion due to the film formation also become a factor of lowering the energy density when viewed as a power storage element.

Further, in the technique of Patent Document 2, since the difference in the lithium ion concentration in the negative electrode active material between the facing portion and the non-opposing portion is small, the potential difference between the negative electrode between the facing portion and the non-opposing portion is small, and the lithium ion is transferred to the non-opposing portion. It is in a state where it is easy to move, and lithium ions that have moved to the non-opposing portion are unlikely to contribute to the charge / discharge reaction, so there is a concern that the capacity may decrease.
As described above, no technology has been found that can sufficiently secure high input / output characteristics and durability against a high load charge / discharge cycle, as well as an excellent energy density that is important for practical use.

Japanese Unexamined Patent Publication No. 2011-12408 Japanese Patent No. 4275192

The present invention has been made in view of the above situation.
Therefore, the problem to be solved by the present invention is to suppress the movement of lithium ions to the non-opposing portion of the negative electrode, which is difficult to contribute to the charge / discharge reaction in the wound power storage element, and to have excellent energy density and high input / output characteristics. It is an object of the present invention to provide a non-aqueous lithium-type power storage element having a high load charge / discharge cycle durability.

The present inventors diligently studied and repeated experiments in order to solve the above-mentioned problems. As a result, the positive electrode contains a lithium compound, and the negative electrode potential of the non-opposing portion is higher than that of the facing portion of the negative electrode, thereby having excellent energy density and high input / output characteristics, and durability against a high load charge / discharge cycle. It has been found that a non-aqueous lithium-type power storage element equipped with the above can be provided.

｛式（１）中、Ｒ^１は、炭素数１〜４のアルキレン基、炭素数１〜４のハロゲン化アルキレン基であり、Ｘ^１、Ｘ^２はそれぞれ独立に−（ＣＯＯ）_ｎ（ここで、ｎは０又は１である。）である。｝

｛式（２）中、Ｒ^１は、炭素数１〜４のアルキレン基、炭素数１〜４のハロゲン化アルキレン基であり、Ｒ^２は水素、炭素数１〜１０のアルキル基、炭素数１〜１０のモノ若しくはポリヒドロキシアルキル基、炭素数２〜１０のアルケニル基、炭素数２〜１０のモノ又はポリヒドロキシアルケニル基、炭素数３〜６のシクロアルキル基、又はアリール基であり、Ｘ^１、Ｘ^２はそれぞれ独立に−（ＣＯＯ）_ｎ（ここで、ｎは０又は１である。）である。｝

｛式（３）中、Ｒ^１は、炭素数１〜４のアルキレン基、炭素数１〜４のハロゲン化アルキレン基であり、Ｒ^２、Ｒ^３はそれぞれ独立に水素、炭素数１〜１０のアルキル基、炭素数１〜１０のモノ若しくはポリヒドロキシアルキル基、炭素数２〜１０のアルケニル基、炭素数２〜１０のモノ又はポリヒドロキシアルケニル基、炭素数３〜６のシクロアルキル基、又はアリール基であり、Ｘ^１、Ｘ^２はそれぞれ独立に−（ＣＯＯ）_ｎ（ここで、ｎは０又は１である。）である。｝
［９］前記正極活物質層に含まれる正極活物質が、ＢＪＨ法により算出した直径２０Å以上５００Å以下の細孔に由来するメソ孔量をＶ１（ｃｃ／ｇ）、ＭＰ法により算出した直径２０Å未満の細孔に由来するマイクロ孔量をＶ２（ｃｃ／ｇ）とするとき、０．３＜Ｖ１≦０．８、及び０．５≦Ｖ２≦１．０を満たし、かつ、ＢＥＴ法により測定される比表面積が１，５００ｍ^２／ｇ以上３，０００ｍ^２／ｇ以下を示す活性炭である、[１]〜[８]のいずれか一項に記載の非水系リチウム型蓄電素子。
［１０］前記正極活物質層に含まれる正極活物質が、ＢＪＨ法により算出した直径２０Å以上５００Å以下の細孔に由来するメソ孔量Ｖ１（ｃｃ／ｇ）が０．８＜Ｖ１≦２．５を満たし、かつ、ＭＰ法により算出した直径２０Å未満の細孔に由来するマイクロ孔量Ｖ２（ｃｃ／ｇ）が０．８＜Ｖ２≦３．０を満たし、さらに、ＢＥＴ法により測定される比表面積が２，３００ｍ^２／ｇ以上４，０００ｍ^２／ｇ以下を示す活性炭である、[１]〜[８]のいずれか一項に記載の非水系リチウム型蓄電素子。
［１１］［１］〜［１０］のいずれか一項に記載の非水系リチウム型蓄電素子において、充放電サイクル時の該非水系リチウム型蓄電素子において、初期の静電容量をＦ（Ｆ）、常温放電内部抵抗をＲａ（Ω）、環境温度２５℃にて、セル電圧を２．２Ｖから３．８Ｖまで、３００Ｃのレートでの高負荷充放電サイクルを６０，０００回行った後の静電容量をＦｅ（Ｆ）常温放電内部抵抗をＲｅ（Ω）、としたとき、以下の：
（ａ）Ｒｅ／Ｒａが０．９０以上１．５以下である；
（ｂ）Ｆｅ／Ｆが０．８０以上
を同時に満たす、前記非水系リチウム型蓄電素子。 The present invention has been made based on this finding.
That is, the present invention is as follows:
[1] A non-aqueous lithium-type power storage element composed of a positive electrode containing a lithium compound other than an active material, a negative electrode, a separator, and a non-aqueous electrolytic solution containing lithium ions.
The positive electrode has a positive electrode current collector, a positive electrode active material layer composed of an active material and a lithium compound is provided on the current collector, and the negative electrode can occlude and release lithium ions on the negative electrode current collector. Contains active material, and also
The positive electrode and the negative electrode consist of an electrode wound body wound via a separator, and in addition,
The negative electrode has a portion facing the positive electrode and the negative electrode facing each other with the separator interposed therebetween.
With the separator interposed therebetween, it has a non-opposing portion in which the opposite positive electrode does not exist, and
A non-aqueous lithium-type power storage element characterized in that the negative electrode potential in the non-opposing portion is 50 mV or more higher than the negative electrode potential in the facing portion.
[2] The non-aqueous lithium-type power storage element according to [1], wherein the negative electrode active material layer in the non-opposing portion has a negative electrode potential gradient of 500 mV / m or more.
[3] The ratio of the lithium ion concentration (mass%) in the negative electrode active material of the non-opposing portion to the lithium ion concentration (mass%) in the negative electrode active material of the facing portion is 0.85 or less. ] Or the non-aqueous lithium-type power storage element according to [2].
[4] The non-item according to any one of [1] to [3], wherein the ratio of the thickness of the negative electrode of the non-opposing portion to the thickness of the negative electrode of the facing portion is 0.80 or more and 0.95 or less. Aqueous lithium-type power storage element.
[5] The non-aqueous system according to any one of [1] to [4], wherein the lithium compound is at least one lithium compound selected from the group consisting of lithium carbonate, lithium oxide, and lithium hydroxide. Lithium type power storage element.
[6] Regarding the solid ⁷ Li-NMR spectrum of the positive electrode active material layer,
When the peak area at -40ppm to 40ppm obtained by the measurement with the repetition waiting time of 10 seconds is a, and the peak area at -40ppm to 40ppm obtained by the measurement with the repetition waiting time of 3000 seconds is b. The non-aqueous lithium-type power storage element according to any one of [1] to [5], wherein 04 ≦ b / a ≦ 5.56.
[7] When the average particle size of the lithium compound is X ₁ , 0.1 μm ≤ X ₁ ≤ 10 μm, and when the average particle size of the positive electrode active material is Y ₁ , 2 μm ≤ Y ₁ ≤ 20 μm. , X ₁ <Y ₁ , and the amount of the lithium compound contained in the positive electrode is 1% by mass or more and 50% by mass or less. The non-aqueous lithium type according to any one of [1] to [6]. Power storage element.
[8] The content of the compound selected from the following general formulas (1) to (3) per unit mass of the negative electrode active material layer in the facing portion is A, and the content per unit mass of the positive electrode active material layer. The non-aqueous lithium-type power storage element according to any one of [1] to [7], wherein 0.2 ≦ A / B ≦ 20 when B is defined as B.

{In formula (1), R ¹ is an alkylene group having 1 to 4 carbon atoms and a halogenated alkylene group having 1 to 4 carbon atoms, and X ¹ and X ² are independently − (COO) _n (here). , N is 0 or 1.). }

{In the formula (2), R ¹ is an alkylene group having 1 to 4 carbon atoms and a halogenated alkylene group having 1 to 4 carbon atoms, and R ² is hydrogen, an alkyl group having 1 to 10 carbon atoms, and 1 carbon atom. A mono or polyhydroxyalkyl group having 10 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a mono or polyhydroxyalkenyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group, X ¹ , X ² are independently − (COO) _n (where n is 0 or 1). }

{In formula (3), R ¹ is an alkylene group having 1 to 4 carbon atoms and a halogenated alkylene group having 1 to 4 carbon atoms, and R ² and R ³ are independently hydrogen and having 1 to 10 carbon atoms, respectively. Alkyl group, mono or polyhydroxyalkyl group with 1 to 10 carbon atoms, alkenyl group with 2 to 10 carbon atoms, mono or polyhydroxyalkenyl group with 2 to 10 carbon atoms, cycloalkyl group with 3 to 6 carbon atoms, or aryl It is a group, and X ¹ and X ² are independently − (COO) _n (where n is 0 or 1). }
[9] The amount of mesopores derived from the pores of the positive electrode active material contained in the positive electrode active material layer having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method is V1 (cc / g), and the diameter is 20 Å calculated by the MP method. When the amount of micropores derived from pores less than is V2 (cc / g), 0.3 <V1 ≦ 0.8 and 0.5 ≦ V2 ≦ 1.0 are satisfied, and the measurement is performed by the BET method. The non-aqueous lithium-type power storage element according to any one of [1] to [8], which is an activated carbon having a specific surface area of 1,500 m ² / g or more and 3,000 m ² / g or less.
[10] The amount of mesopores V1 (cc / g) of the positive electrode active material contained in the positive electrode active material layer derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method is 0.8 <V1 ≦ 2. The amount of micropores V2 (cc / g) derived from pores having a diameter of less than 20 Å calculated by the MP method and satisfying 5 satisfies 0.8 <V2 ≦ 3.0, and is further measured by the BET method. The non-aqueous lithium-type power storage element according to any one of [1] to [8], which is an activated carbon having a specific surface area of 2,300 m ² / g or more and 4,000 m ² / g or less.
[11] In the non-aqueous lithium-type power storage element according to any one of [1] to [10], the initial capacitance of the non-aqueous lithium-type power storage element during the charge / discharge cycle is F (F). Room temperature discharge Internal resistance is Ra (Ω), environmental temperature is 25 ° C, cell voltage is from 2.2V to 3.8V, and capacitance after 60,000 high-load charge / discharge cycles at a rate of 300C. When the capacitance is Fe (F) and the internal resistance of normal temperature discharge is Re (Ω), the following:
(A) Re / Ra is 0.90 or more and 1.5 or less;
(B) The non-aqueous lithium-type power storage element having Fe / F of 0.80 or more at the same time.

According to the present invention, it is possible to provide a non-aqueous lithium-type power storage element having excellent energy density, high input / output characteristics, and durability against a high load charge / discharge cycle.

An example of a wound body is shown. The disassembled side view of the wound body is shown. The schematic diagram which divided the negative electrode non-opposing part at the time of potential gradient measurement is shown.

Hereinafter, embodiments of the present invention will be described in detail.
Non-aqueous lithium-type power storage elements generally include a positive electrode, a negative electrode, a separator, an electrolytic solution, and an exterior body as main components.

[Positive electrode]
The positive electrode has a positive electrode current collector and a positive electrode active material layer existing on one side or both sides thereof.
Further, the positive electrode preferably contains a lithium compound as a positive electrode precursor before assembling the power storage element. As will be described later, in the present embodiment, it is preferable to pre-dope the negative electrode with lithium ions in the energy storage element assembly process, but as the pre-doping method, a positive electrode precursor containing the lithium compound, a negative electrode, a separator, an exterior body, and the like. It is preferable to apply a voltage between the positive electrode precursor and the negative electrode after assembling the power storage element using the non-aqueous electrolyte solution. The lithium compound is preferably contained in the positive electrode active material layer formed on the positive electrode current collector of the positive electrode precursor.
In the present specification, the positive electrode state before the lithium doping step is defined as a positive electrode precursor, and the positive electrode state after the lithium doping step is defined as a positive electrode.

[Positive electrode active material layer]

The positive electrode active material layer contained in the positive electrode contains a positive electrode active material containing activated carbon. In addition to this, the positive electrode active material layer may contain an optional component such as a conductive filler, a binder, and a dispersion stabilizer, if necessary.
Further, it is preferable that the positive electrode active material layer of the positive electrode precursor contains a lithium compound other than the positive electrode active material.

[Positive electrode active material]
The positive electrode active material contains activated carbon. As the positive electrode active material, only activated carbon may be used, or in addition to activated carbon, other carbon materials as described later may be used in combination. As the carbon material, it is more preferable to use carbon nanotubes, a conductive polymer, or a porous carbon material. The positive electrode active material may be used by mixing one or more kinds of carbon materials including activated carbon, or may contain a material other than the carbon material (for example, a composite oxide of lithium and a transition metal). The content of the carbon material with respect to the total amount of the positive electrode active material is preferably 50% by mass or more, and more preferably 70% by mass or more. The content of the carbon material can be 100% by mass, but from the viewpoint of obtaining a good effect by using other materials in combination, for example, it is preferably 90% by mass or less, and 80% by mass or less. May be good.

There are no particular restrictions on the type of activated carbon used as the positive electrode active material and its raw material. However, it is preferable to optimally control the pores of the activated carbon in order to achieve both high input / output characteristics and high energy density. Specifically, the amount of mesopores derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method is V1 (cc / g), and the amount of micropores derived from pores having a diameter of less than 20 Å calculated by the MP method. When setting to V2 (cc / g)
(1) For high input / output characteristics, 0.3 <V1 ≦ 0.8 and 0.5 ≦ V2 ≦ 1.0 are satisfied, and the specific surface area measured by the BET method is 1,500 m ^2. Activated carbon having a / g or more and 3,000 m ² / g or less (hereinafter, also referred to as activated carbon 1) is preferable.
(2) In order to obtain a high energy density, 0.8 <V1 ≦ 2.5 and 0.8 <V2 ≦ 3.0 are satisfied, and the specific surface area measured by the BET method is 2,300 m ^2. Activated carbon having an / g or more and 4,000 m ² / g or less (hereinafter, also referred to as activated carbon 2) is preferable.
Hereinafter, the (1) activated carbon 1 and the (2) activated carbon 2 will be described individually in sequence.

[Activated carbon 1]
The mesopore amount V1 of the activated carbon 1 is preferably a value larger than 0.3 cc / g in terms of increasing the input / output characteristics when incorporated in the power storage element. On the other hand, it is preferably 0.8 cc / g or less from the viewpoint of suppressing a decrease in the bulk density of the positive electrode. The above V1 is more preferably 0.35 cc / g or more and 0.7 cc / g or less, and further preferably 0.4 cc / g or more and 0.6 cc / g or less.
The micropore amount V2 of the activated carbon 1 is preferably 0.5 cc / g or more in order to increase the specific surface area and the capacity of the activated carbon. On the other hand, it is preferably 1.0 cc / g or less from the viewpoint of suppressing the bulk of the activated carbon, increasing the density as an electrode, and increasing the capacity per unit volume. The above V2 is more preferably 0.6 cc / g or more and 1.0 cc / g or less, and further preferably 0.8 cc / g or more and 1.0 cc / g or less. The combination of the lower limit and the upper limit can be arbitrary.

The ratio of the mesopore amount V1 to the micropore amount V2 (V1 / V2) is preferably in the range of 0.3 ≦ V1 / V2 ≦ 0.9. That is, V1 / V2 is preferably 0.3 or more from the viewpoint of increasing the ratio of the mesopore amount to the micropore amount to the extent that the decrease in output characteristics can be suppressed while maintaining a high capacity. On the other hand, V1 / V2 is preferably 0.9 or less from the viewpoint of increasing the ratio of the micropore amount to the mesopore amount to the extent that the decrease in capacitance can be suppressed while maintaining the high output characteristics. A more preferable range of V1 / V2 is 0.4 ≦ V1 / V2 ≦ 0.7, and a more preferable range of V1 / V2 is 0.55 ≦ V1 / V2 ≦ 0.7. The combination of the lower limit and the upper limit can be arbitrary.

The average pore diameter of the activated carbon 1 is preferably 17 Å or more, more preferably 18 Å or more, and most preferably 20 Å or more from the viewpoint of maximizing the output of the obtained power storage element. Further, from the viewpoint of maximizing the capacity, the average pore diameter of the activated carbon 1 is preferably 25 Å or less.

BET specific surface area of the activated carbon 1 is preferably from 1,500 m ² / g or more 3,000 m ² / g, more preferably not more than 1,500 m ² / g or more 2,500 m ² / g. When the BET specific surface area is 1,500 m ² / g or more, a good energy density can be easily obtained, while when the BET specific surface area is 3,000 m ² / g or less, in order to maintain the strength of the electrode. Since it is not necessary to add a large amount of binder, the performance per electrode volume is improved. The combination of the lower limit and the upper limit can be arbitrary.
Activated carbon 1 having the above characteristics can be obtained, for example, by using the raw materials and treatment methods described below.

In the present embodiment, the carbon source used as the raw material of the activated carbon 1 is not particularly limited. For example, plant-based raw materials such as wood, wood flour, coconut shells, by-products during pulp production, bagas, waste sugar honey; peat, sub-charcoal, brown charcoal, bituminous charcoal, smokeless charcoal, petroleum distillation residue components, petroleum pitch, coke, coal tar, etc. Fossil raw materials; various synthetic resins such as phenol resin, vinyl chloride resin, vinyl acetate resin, melamine resin, urea resin, resorcinol resin, celluloid, epoxy resin, polyurethane resin, polyester resin, polyamide resin; polybutylene, polybutadiene, polychloroprene, etc. Synthetic rubber; other synthetic wood, synthetic pulp, etc., and carbonized products thereof. Among these raw materials, plant-based raw materials such as coconut shells and wood flour and their carbides are preferable, and coconut shell carbides are particularly preferable, from the viewpoint of mass production and cost.
As a carbonization and activation method for converting these raw materials into the activated carbon 1, for example, known methods such as a fixed bed method, a moving bed method, a fluidized bed method, a slurry method, and a rotary kiln method can be adopted.
Examples of the carbonization method for these raw materials include inert gases such as nitrogen, carbon dioxide, helium, argon, xenone, neon, carbon monoxide, and combustion exhaust gas, or other gases containing these inert gases as main components. Examples thereof include a method of firing at about 400 to 700 ° C. (preferably 450 to 600 ° C.) for about 30 minutes to 10 hours using a mixed gas.

As a method for activating the carbide obtained by the above carbonization method, a gas activation method in which the carbide is fired using an activation gas such as steam, carbon dioxide, or oxygen is preferably used. Of these, a method using steam or carbon dioxide as the activating gas is preferable.
In this activation method, the above-mentioned carbide is supplied for 3 to 12 hours (preferably 5 to 11) while supplying the activation gas at a ratio of 0.5 to 3.0 kg / h (preferably 0.7 to 2.0 kg / h). It is preferable to activate by raising the temperature to 800 to 1,000 ° C. over time, more preferably 6 to 10 hours).
Further, the carbide may be first activated in advance prior to the activation treatment of the carbide. In this primary activation, a method in which a carbon material is usually calcined at a temperature of less than 900 ° C. using an activation gas such as steam, carbon dioxide, or oxygen to activate the gas can be preferably adopted.
By appropriately combining the calcination temperature and calcination time in the carbonization method with the activation gas supply amount, temperature rise rate, and maximum activation temperature in the activation method, activated carbon 1 having the above characteristics that can be used in the present embodiment is produced. can do.

The average particle size of the activated carbon 1 is preferably 2 to 20 μm.
When the average particle size is 2 μm or more, the capacity per electrode volume tends to be high because the density of the active material layer is high. Here, if the average particle size is small, the durability may be low, but if the average particle size is 2 μm or more, such a defect is unlikely to occur. On the other hand, when the average particle size is 20 μm or less, it tends to be easily adapted to high-speed charging / discharging. The average particle size is more preferably 2 to 15 μm, still more preferably 3 to 10 μm. The upper and lower limits of the average particle size range can be arbitrarily combined.

[Activated carbon 2]
The mesopore amount V1 of the activated carbon 2 is preferably a value larger than 0.8 cc / g from the viewpoint of increasing the output characteristics when incorporated in the power storage element. On the other hand, V1 is preferably 2.5 cc / g or less from the viewpoint of suppressing a decrease in the capacity of the power storage element. The above V1 is more preferably 1.00 cc / g or more and 2.0 cc / g or less, and further preferably 1.2 cc / g or more and 1.8 cc / g or less.

On the other hand, the micropore amount V2 of the activated carbon 2 is preferably a value larger than 0.8 cc / g in order to increase the specific surface area and the capacity of the activated carbon. On the other hand, V2 is 3.0 cc / g or less, more preferably more than 1.0 cc / g and 2.5 cc / g or less, from the viewpoint of increasing the density of activated carbon as an electrode and increasing the capacity per unit volume. More preferably, it is 1.5 cc / g or more and 2.5 cc / g or less.

The activated carbon 2 having the above-mentioned meso-pore amount and micro-pore amount has a higher BET specific surface area than the activated carbon used for conventional electric double layer capacitors or lithium ion capacitors. The specific value of the BET specific surface area of the activated carbon 2 is preferably 2,300 m ² / g or more and 4,000 m ² / g or less. The lower limit of the BET specific surface area, more preferably 3,00m ² / g or more, more preferably 3,200 m ² / g or more. On the other hand, the upper limit of the BET specific surface area is more preferably 3,800 m ² / g or less. When the BET specific surface area is 2,300 m ² / g or more, a good energy density can be easily obtained, while when the BET specific surface area is 4,000 m ² / g or less, in order to maintain the strength of the electrode. Since it is not necessary to add a large amount of binder, the performance per electrode volume is improved.
Regarding the V1, V2 and BET specific surface areas of the activated carbon 2, the upper and lower limits of the preferable ranges described above can be arbitrarily combined.

Activated carbon 2 having the above characteristics can be obtained by using, for example, the raw materials and treatment methods described below.
The carbon source used as a raw material for activated carbon 2 is not particularly limited as long as it is a carbon source normally used as a raw material for activated carbon. For example, plant-based raw materials such as wood, wood flour, and coconut shell; petroleum pitch, coke. Fossil-based raw materials such as, phenol resin, furan resin, vinyl chloride resin, vinyl acetate resin, melamine resin, urea resin, various synthetic resins such as resorcinol resin and the like can be mentioned. Among these raw materials, phenol resin and furan resin are particularly preferable because they are suitable for producing activated carbon having a high specific surface area.

Examples of the method of carbonizing these raw materials or the heating method at the time of activation treatment include known methods such as a fixed bed method, a moving bed method, a fluidized bed method, a slurry method, and a rotary kiln method. As the atmosphere at the time of heating, an inert gas such as nitrogen, carbon dioxide, helium, or argon, or a gas containing these inert gases as a main component and mixed with other gases is used. It is preferable to bake at a carbonization temperature of about 400 to 700 ° C. (the lower limit is preferably 450 ° C. or higher, more preferably 500 ° C. or higher, and the upper limit is preferably 650 ° C. or lower) for about 0.5 to 10 hours.

Examples of the method for activating the carbide after the carbonization treatment include a gas activation method in which the carbide is fired using an activated gas such as steam, carbon dioxide, and oxygen, and an alkali metal activation method in which heat treatment is performed after mixing with an alkali metal compound. The alkali metal activation method is preferable for producing activated carbon having a high specific surface area.
In this activation method, the carbides were mixed so that the mass ratio of the carbides to the alkali metal compounds such as KOH and NaOH was 1: 1 or more (the amount of the alkali metal compounds was the same as or larger than the amount of the carbides). Later, heating is carried out in the range of 600 to 900 ° C. (preferably 650 ° C. to 850 ° C.) in an inert gas atmosphere for 0.5 to 5 hours, after which the alkali metal compound is washed and removed with acid and water, and further dried. I do.

I mentioned earlier that the mass ratio of carbide to alkali metal compound (= carbide: alkali metal compound) is preferably 1: 1 or more. However, as the amount of alkali metal compound increases, the amount of mesopores increases, but the mass ratio is 1: 1. Since the amount of pores tends to increase sharply around 3.5, the mass ratio is preferably more than 1: 3 and the amount of the alkali metal compound is preferably 1: 5.5 or less. The mass ratio increases as the amount of the alkali metal compound increases, but it is preferably in the above range in consideration of treatment efficiency such as subsequent cleaning.
In order to increase the amount of micropores and not to increase the amount of mesopores, it is advisable to increase the amount of carbides at the time of activation and mix with KOH. In order to increase both the amount of micropores and the amount of mesopores, it is advisable to use a large amount of KOH. Further, in order to mainly increase the amount of mesopores, it is preferable to perform steam activation after performing alkali activation treatment.
The average particle size of the activated carbon 2 is preferably 2 μm or more and 20 μm or less, and more preferably 3 μm or more and 10 μm or less.

[Usage of activated carbon]
Activated carbons 1 and 2 may be one type of activated carbon, or may be a mixture of two or more types of activated carbon, and each of the above-mentioned characteristic values may be shown as a whole mixture.
As the activated carbons 1 and 2 described above, either one of them may be selected and used, or both may be mixed and used.
The positive electrode active material is a material other than activated carbon 1 and 2 (for example, activated carbon that does not have the specific V1 and / or V2, or a material other than activated carbon (for example, a composite oxide of lithium and a transition metal)). It may be included. In an exemplary embodiment, the content of activated carbon 1, the content of activated carbon 2, or the total content of activated carbons 1 and 2 is preferably more than 50% by mass, respectively, and 70% by mass or more of the total positive electrode active material. More preferably, 90% by mass or more is further preferable, and 100% by mass is most preferable.

The content ratio of the positive electrode active material in the positive electrode active material layer is preferably 35% by mass or more and 95% by mass or less based on the total mass of the positive electrode active material layer in the positive electrode precursor. The upper limit of the content ratio of the positive electrode active material is more preferably 45% by mass or more, and further preferably 55% by mass or more. On the other hand, the lower limit of the content ratio of the positive electrode active material is more preferably 90% by mass or less, and further preferably 80% by mass or less. By setting the content ratio in this range, suitable charge / discharge characteristics are exhibited.

[Lithium compound]
The positive electrode active material layer of the positive electrode precursor of the present embodiment preferably contains a lithium compound other than the positive electrode active material. Further, the positive electrode active material layer of the positive electrode of the present embodiment contains a lithium compound other than the positive electrode active material.
The lithium compound can be decomposed at the positive electrode in the lithium doping step described later to release lithium ions, such as lithium carbonate, lithium oxide, lithium hydroxide, lithium fluoride, lithium chloride, lithium oxalate, and iodine. One or more selected from lithium carbonate, lithium nitride, lithium oxalate, and lithium acetate are preferably used. Among them, lithium carbonate, lithium oxide, and lithium hydroxide are more preferable, and lithium carbonate is more preferably used from the viewpoint that it can be handled in the air and has low hygroscopicity. Such a lithium compound decomposes when a voltage is applied, functions as a dopant source for lithium doping to the negative electrode, and forms pores in the positive electrode active material layer. Therefore, the electrolytic solution has excellent retention and ionic conductivity. It is possible to form an excellent positive electrode.
Further, since the lithium compound decomposed by the voltage is preferentially doped into the non-opposing portion of the negative electrode over the non-opposing portion of the negative electrode, lithium doping into the non-opposing portion of the negative electrode is suppressed, and the negative electrode potential can be increased. .. The negative electrode potential in the present specification indicates a potential based on metallic lithium.

[Lithium compound of positive electrode precursor]
The lithium compound is preferably in the form of particles. The average particle size of the lithium compound contained in the positive electrode precursor is preferably 0.1 μm or more and 100 μm or less. The upper limit of the average particle size of the lithium compound contained in the positive electrode precursor is more preferably 50 μm or less, further preferably 20 μm or less, and most preferably 10 μm or less. On the other hand, the lower limit of the average particle size of the lithium compound contained in the positive electrode precursor is more preferably 0.3 μm or more, and further preferably 0.5 μm or more. When the average particle size of the lithium compound is 0.1 μm or more, the pores remaining after the oxidation reaction of the lithium compound in the positive electrode have a sufficient volume to hold the electrolytic solution, so that the high load charge / discharge characteristics are exhibited. improves. When the average particle size of the lithium compound is 100 μm or less, the surface area of the lithium compound does not become excessively small, so that the rate of oxidation reaction of the lithium compound can be ensured. The upper and lower limits of the range of the average particle size of the lithium compound can be arbitrarily combined.
Various methods can be used for atomizing the lithium compound. For example, a crusher such as a ball mill, a bead mill, a ring mill, a jet mill, or a rod mill can be used.

The content ratio of the lithium compound in the positive electrode active material layer of the positive electrode precursor is preferably 5% by mass or more and 60% by mass or less based on the total mass of the positive electrode active material layer in the positive electrode precursor, and is preferably 10% by mass or more and 50% by mass or more. It is more preferably mass% or less. By setting the content ratio in this range, it is possible to exert a suitable function as a dopant source for the negative electrode and to impart an appropriate degree of porosity to the positive electrode, and both of them achieve high load charge / discharge efficiency. It is preferable because it can provide an excellent power storage element. The upper and lower limits of this content ratio range can be arbitrarily combined.

[Lithium compound of positive electrode]
The positive electrode contains a lithium compound other than the positive electrode active material. When the average particle size of the lithium compound other than the positive electrode active material contained in the positive electrode is X ₁ , it is preferably 0.1 μm ≦ X ₁ ≦ 10 μm. More preferably, it is 0.5 μm ≦ X ₁ ≦ 5 μm. When X ₁ is 0.1 μm or more, the high load charge / discharge cycle characteristics are improved by adsorbing the fluorine ions generated in the high load charge / discharge cycle. When X ₁ is 10 μm or less, the reaction area with the fluorine ions generated in the high load charge / discharge cycle increases, so that the adsorption of fluorine ions can be performed efficiently.

The lithium compound contained in the positive electrode other than the positive electrode active material is characterized by being 1% by mass or more and 50% by mass or less based on the total mass of the positive electrode active material layer in the positive electrode, and is 2.5% by mass or more and 25% by mass. More preferably, it is less than%. When the amount of the lithium compound is 1% by mass or more, lithium carbonate suppresses the decomposition reaction of the electrolytic solution solvent on the positive electrode in a high temperature environment, so that the high temperature durability is improved, and the effect is improved when the amount is 2.5% by mass or more. Becomes noticeable. Further, when the amount of the lithium compound is 50% by mass or less, the electron conductivity between the positive electrode active materials is relatively small to be inhibited by the lithium compound, so that high input / output characteristics are exhibited, and the amount is 25% by mass or less. , Especially preferable from the viewpoint of input / output characteristics. The combination of the lower limit and the upper limit can be arbitrary.

In the solid ⁷ Li-NMR spectrum of the positive electrode active material layer of the present embodiment, the peak area at -40 ppm to 40 ppm obtained by the measurement with the repetition waiting time of 10 seconds was defined as a, and the repetition waiting time was set to 3000 seconds. When the peak area at -40 ppm to 40 ppm obtained is b, 1.04 ≦ b / a ≦ 5.56. The amount of lithium is preferably 1.05 ≦ b / a ≦ 3.79, more preferably 1.09 ≦ b / a ≦ 3.32, still more preferably 1.14 ≦ b / a ≦ 2.86. More preferably, it is 1.18 ≦ b / a ≦ 1.93. The lower limit and the upper limit can be any combination.

By adjusting the b / a to a specific range, high load charge / discharge cycle characteristics can be improved while maintaining high input / output characteristics. The principle is not clear, but it is inferred as follows. The peak area a is considered to be a peak mainly derived from lithium ions occluded in the positive electrode active material and the attached lithium-containing film, and is considered to relatively represent the amount of the positive electrode active material. On the other hand, the peak area b is considered to be the sum of the peak area a and the peak derived from the lithium compound isolated from the positive electrode active material. That is, the b / a is considered to represent the amount of the isolated lithium compound with respect to the positive electrode active material. The lithium compound isolated from the positive electrode active material can maintain high input / output characteristics without hindering electron conduction and ion diffusion between the positive electrode active materials. Further, the lithium compound adsorbs active products such as fluorine ions generated in the high load charge / discharge cycle, so that the high load charge / discharge cycle characteristics are improved. In addition, "isolated" means, for example, a state in which particles of a lithium compound are isolated and dispersed inside the positive electrode active material when it is an aggregate of activated carbon particles.

When the b / a is 1.04 or more, the amount of the lithium compound with respect to the positive electrode active material is sufficient, so that the lithium compound adsorbs active products such as fluorine ions generated in the high load charge / discharge cycle. High load charge / discharge cycle characteristics are improved. On the other hand, when this b / a is 5.56 or less, the lithium compound can maintain high input / output characteristics without inhibiting electron conduction and ion diffusion between the positive electrode active materials.
In the present specification, in the solid ⁷ Li-NMR spectrum of the positive electrode active material layer, the peak area a at -40 ppm to 40 ppm when the repetition time is 10 seconds and -40 ppm to 40 ppm when the repetition time is 3000 seconds. The area ratio b / a to the peak area b in is calculated by the following method.

As a solid ⁷ Li-NMR measuring device, a commercially available device can be used. In a room temperature environment, the rotation speed of the magic angle spinning is 14.5 kHz, the irradiation pulse width is 45 ° pulse, and the measurement is performed by the single pulse method. Measurements are made for each of the cases where the repetition time is set to 10 seconds and 3000 seconds, and a solid ⁷ Li-NMR spectrum is obtained. When acquiring the solid ⁷ Li-NMR spectrum, the measurement conditions other than the repetition waiting time, that is, the number of integrations, the receiver gain, and the like are all the same. A 1 mol / L lithium chloride aqueous solution is used as a shift reference, and the shift position measured separately as an external standard is 0 ppm. When measuring the lithium chloride aqueous solution, the sample is not rotated, and the irradiation pulse width is set to 45 ° pulse, and the measurement is performed by the single pulse method.
The peak areas a and b at -40 ppm to 40 ppm are obtained from the solid ⁷ Li-NMR spectrum of the positive electrode active material layer obtained by the above method, and b / a is calculated.

[Method for identifying lithium compounds in positive electrode]
The method for identifying the lithium compound contained in the positive electrode is not particularly limited, but for example, it can be identified by the following method. For identification of the lithium compound, it is preferable to identify by combining a plurality of analysis methods described below.
When measuring SEM-EDX, Raman, and XPS described below, disassemble the non-aqueous lithium-type power storage element in an argon box, take out the positive electrode, clean the electrolyte adhering to the positive electrode surface, and then perform the measurement. Is preferable. As for the method for cleaning the positive electrode, since the electrolyte adhering to the surface of the positive electrode may be washed away, a carbonate solvent such as dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate can be preferably used. As a cleaning method, for example, the positive electrode is immersed in a diethyl carbonate solvent having a mass of 50 to 100 times the positive electrode for 10 minutes or more, and then the solvent is replaced and the positive electrode is immersed again. After that, the positive electrode is taken out from diethyl carbonate, and vacuum dried (temperature: 0 to 200 ° C., pressure: 0 to 20 kPa, time: 1 to 40 hours, and the condition is that the residual diethyl carbonate in the positive electrode is 1% by mass or less. The residual amount of diethyl carbonate can be quantified based on the calibration line prepared in advance by measuring the GC / MS of the water after washing with distilled water and adjusting the liquid amount, which will be described later.) -Perform EDX, Raman, and XPS analysis.

Regarding ion chromatography described later, anions can be identified by analyzing the water after washing the positive electrode with distilled water.
If the lithium compound cannot be identified by the above analysis method, other analysis methods include solid ⁷ Li-NMR, XRD (X-ray diffraction), TOF-SIMS (time-of-flight secondary ion mass spectrometry), and AES (Auger). Lithium compounds can also be identified by using electron spectroscopy), TPD / MS (heat-of-flight mass spectrometry), DSC (differential scanning calorie analysis), and the like.

[SEM-EDX]
The oxygen-containing lithium compound and the positive electrode active material can be identified by oxygen mapping using an SEM-EDX image of the positive electrode surface measured at an observation magnification of 1000 to 4000 times. As a measurement example of the SEM-EDX image, the acceleration voltage can be measured as 10 kV, the emission current as 1 μA, the number of measurement pixels as 256 × 256 pixels, and the number of integrations as 50 times. In order to prevent the sample from being charged, gold, platinum, osmium or the like can be surface-treated by a method such as vacuum deposition or sputtering. Regarding the method for measuring the SEM-EDX image, it is preferable to adjust the brightness and contrast so that the brightness does not reach the maximum brightness and the average value of the brightness is in the range of 40% to 60%. Particles containing 50% or more of bright areas binarized with respect to the obtained oxygen mapping based on the average value of brightness are designated as lithium compounds.

[Raman]
The lithium compound composed of carbonate ions and the positive electrode active material can be identified by Raman imaging of the positive electrode surface measured at an observation magnification of 1000 to 4000 times. As an example of measurement conditions, the excitation light is 532 nm, the excitation light intensity is 1%, the long operation of the objective lens is 50 times, the diffraction grating is 1800 gr / mm, the mapping method is point scanning (slit 65 mm, binning 5 pix), 1 mm step, The exposure time per point can be measured for 3 seconds, the number of integrations can be measured once, and the measurement can be performed under the condition of having a noise filter. For the measured Raman spectrum, a straight baseline is set in the range of 1071-1104 cm ^-1 , the area is calculated with a positive value from the baseline as the peak of carbonate ion, and the frequency is integrated. At this time, the noise component is added. The frequency for the carbonate ion peak area approximated by the Gaussian function is subtracted from the carbonate ion frequency distribution.

[XPS]
The bonding state of lithium can be determined by analyzing the electronic state of lithium by XPS. As an example of measurement conditions, the X-ray source is monochromatic AlKα, the X-ray beam diameter is 100 μmφ (25 W, 15 kV), the path energy is narrow scan: 58.70 eV, there is charge neutralization, and the number of sweeps is narrow scan: 10 times. (Carbon, oxygen) 20 times (fluorine) 30 times (phosphorus) 40 times (lithium) 50 times (silicon), energy steps can be measured under the conditions of narrow scan: 0.25 eV. It is preferable to clean the surface of the positive electrode by sputtering before measuring XPS. As the sputtering conditions, for example, the surface of the positive electrode can be cleaned under the condition of an acceleration voltage of 1.0 kV, 2 mm × 2 mm for 1 minute (1.25 nm / min in terms of SiO ₂ ). Regarding the obtained XPS spectrum, the peak of Li1s binding energy of 50 to 54 eV is LiO ₂ or Li-C bond, and the peak of 55 to 60 eV is LiF, Li ₂ CO ₃ , Li _x PO _y F _z (x in the formula, x, y, z is an integer from 1 to 6), the peak of C1s of the bond energy 285 eV C-C bonds, the peak of 286 eV CO bond, COO peaks 288 eV, the peak of 290~292eV _CO ^{3 2 −} , CF binding, binding energy of O1s 527 to 530 eV peak is O ^2- (Li ₂ O), 531 to 532 eV peak is CO, CO ₃ , OH, PO _x (in the formula, x is 1 to 4) (In the formula, x is an integer of 1 to 4), SiO _x (in the formula, x is an integer of 1 to 4), the peak of 533 eV is CO, SiO _x (in the formula, x is an integer of 1 to 4), F1s. the peak of binding energy 685eV LiF, a peak of 687 eV C-F _bond, Li x _PO y _{F z} (wherein, x, y, z are an integer of 1 to _6), ^PF 6 _-, the binding energy of P2p For, the peak of 133 eV is PO _x (in the formula, x is an integer of 1 to 4), the peak of 134 to 136 eV is PF _x (in the formula, x is an integer of 1 to 6), and the binding energy of Si2p. the peak of 99 eV Si, silicides, (wherein, x, y are arbitrary integers) peaks 101~107eV _Si x _{O y} can be assigned as. When the peaks of the obtained spectrum overlap, it is preferable to separate the peaks assuming a Gaussian function or a Lorentz function and assign the spectra. The existing lithium compound can be identified from the measurement result of the electronic state and the result of the presence element ratio obtained above.

[Ion chromatography]
By analyzing the distilled water washing solution of the positive electrode by ion chromatography, the anion species eluted in water can be identified. As the column to be used, an ion exchange type, an ion exclusion type, and a reverse phase ion pair type can be used. As the detector, an electric conductivity detector, an ultraviolet visible absorptiometric detector, an electrochemical detector, etc. can be used, and a suppressor method in which a suppressor is installed in front of the detector, or electricity without a suppressor. A non-suppressor method using a solution having low conductivity as an eluent can be used. In addition, since mass spectrometer and charged particle detection can be measured in combination with a detector, an appropriate column and detector are combined based on the lithium compound identified from the analysis results of SEM-EDX, Raman, and XPS. Is preferable.
The retention time of the sample is constant for each ion species component if conditions such as the column to be used and the eluent are determined, and the magnitude of the peak response differs for each ion species but is proportional to the concentration. By measuring in advance a standard solution having a known concentration that ensures traceability, it is possible to qualitatively and quantify the ionic species component.

[Method for quantifying lithium compounds]
The method for quantifying the lithium compound contained in the positive electrode is described below.
The positive electrode can be washed with an organic solvent, then washed with distilled water, and the lithium compound can be quantified from the change in positive mass before and after washing with distilled water. Although area measurement is positive is not particularly limited, it is preferably, more preferably 25 cm ² or more 150 cm ² or less from the viewpoint of reducing the variation in measurement is 5 cm ² or more 200 cm ² or less. If the area is 5 cm ² or more, the reproducibility of measurement is ensured. If the area is 200 cm ² or less, the handling of the sample is excellent. For cleaning with an organic solvent, the organic solvent is not particularly limited as long as the non-aqueous electrolyte decomposition product deposited on the surface of the positive electrode can be removed. However, by using an organic solvent having a solubility of the lithium compound of 2% or less, the lithium compound can be used. It is preferable because the elution of the solvent is suppressed. For example, polar solvents such as methanol and acetone are preferably used.

により算出できる。 The method for cleaning the positive electrode is to sufficiently immerse the positive electrode in a methanol solution 50 to 100 times the mass of the positive electrode for 3 days or more. At this time, it is preferable to take measures such as covering the container so that methanol does not volatilize. After that, the positive electrode is taken out from methanol and vacuum dried (temperature: 100 to 200 ° C., pressure: 0 to 10 kPa, time: 5 to 20 hours, and the condition is that the residual amount of methanol in the positive electrode is 1% by mass or less. The residual amount of the above can be quantified by measuring the GC / MS of the water after washing with distilled water, which will be described later, based on the calibration line prepared in advance.) The mass of the positive electrode at that time is M ₀ [g]. And. Subsequently, the positive electrode is sufficiently immersed in distilled water having 100 times the mass of the positive electrode (100M ₀ [g]) for 3 days or more. At this time, it is preferable to take measures such as covering the container so that the distilled water does not volatilize. After immersion least 3 days, a distilled water outlet of the positive electrode (when measuring the above-described ion chromatography, the amount of distilled water to adjust the volume so that the 100M 0 _[g].), Of the Vacuum dry in the same way as methanol washing. The mass of the positive electrode at this time is set to M ₁ [g], and subsequently, in order to measure the mass of the collected positive electrode of the obtained positive electrode, a positive electrode active material layer on the current collector is used using a spatula, a brush, a brush, or the like. Get rid of. Assuming that the mass of the obtained positive electrode current collector is M ₂ [g], the mass% Z of the lithium compound contained in the positive electrode is calculated by the following mathematical formula (1):

Can be calculated by

[Arbitrary component of positive electrode active material layer]
If necessary, the positive electrode active material layer in the present embodiment may contain optional components such as a conductive filler, a binder, and a dispersion stabilizer in addition to the positive electrode active material and the lithium compound.
The conductive filler is not particularly limited, and for example, acetylene black, ketjen black, vapor-grown carbon fiber, graphite, carbon nanotubes, a mixture thereof and the like can be used. The amount of the conductive filler used is preferably 0 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the positive electrode active material. It is more preferably 0.01 parts by mass or more and 20 parts by mass or less, and further preferably 1 part by mass or more and 15 parts by mass or less. If the amount of the conductive filler used is more than 30 parts by mass, the content ratio of the positive electrode active material in the positive electrode active material layer decreases, and the energy density per volume of the positive electrode active material layer decreases, which is not preferable.
The binder is not particularly limited, but for example, PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), polyimide, latex, styrene-butadiene copolymer, fluororubber, acrylic copolymer and the like. Can be used. The amount of the binder used is preferably 1 part by mass or more and 30 parts by mass or less, more preferably 3 parts by mass or more and 27 parts by mass or less, and further preferably 5 parts by mass or more and 25 parts by mass with respect to 100 parts by mass of the positive electrode active material. It is less than a part. When the amount of the binder used is 1 part by mass or more, sufficient electrode strength is exhibited. On the other hand, when the amount of the binder used is 30 parts by mass or less, high input / output characteristics are exhibited without inhibiting the entry / exit and diffusion of ions into the positive electrode active material.
The dispersion stabilizer is not particularly limited, but for example, PVP (polyvinylpyrrolidone), PVA (polyvinyl alcohol), a cellulose derivative and the like can be used. The amount of the dispersion stabilizer used is preferably 0 parts by mass or 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the positive electrode active material. When the amount of the dispersion stabilizer used is 10 parts by mass or less, high input / output characteristics are exhibited without inhibiting the entry / exit and diffusion of ions into the positive electrode active material.

[Positive current collector]
The material constituting the positive electrode current collector in the present embodiment is not particularly limited as long as it has high electron conductivity and does not deteriorate due to elution into the electrolytic solution and reaction with the electrolyte or ions. Foil is preferred. Aluminum foil is particularly preferable as the positive electrode current collector in the non-aqueous lithium power storage device of the present embodiment.
The metal foil may be an ordinary metal foil having no irregularities or through holes, a metal foil having irregularities subjected to embossing, chemical etching, electrolytic precipitation, blasting, etc., expanded metal, punching metal, etc. , A metal foil having through holes such as an etching foil may be used.
The thickness of the positive electrode current collector is not particularly limited as long as the shape and strength of the positive electrode can be sufficiently maintained, but is preferably 1 to 100 μm, for example.

[Manufacturing of positive electrode precursor]
In the present embodiment, the positive electrode precursor serving as the positive electrode of the non-aqueous lithium-type power storage element can be manufactured by a technique for manufacturing electrodes in known lithium ion batteries, electric double layer capacitors, and the like. For example, a positive electrode active material, a lithium compound, and other optional components used as necessary are dispersed or dissolved in water or an organic solvent to prepare a slurry coating solution, and this coating solution is collected as a positive electrode. A positive electrode precursor can be obtained by applying a coating film on one or both sides of an electric body to form a coating film and drying the coating film. Further, the obtained positive electrode precursor may be pressed to adjust the film thickness or bulk density of the positive electrode active material layer. Alternatively, without the use of a solvent, the positive electrode active material and the lithium compound, and any other optional components used as needed, are dry mixed, the resulting mixture is press molded and then conductively bonded. It is also possible to attach the agent to the positive electrode current collector.

The coating liquid of the positive electrode precursor is a dry blend of a part or all of various material powders including a positive electrode active material, and then water or an organic solvent and / or a binder or a dispersion stabilizer is dissolved or dispersed therein. The liquid or slurry-like substance may be added and prepared. Further, even if various material powders containing a positive electrode active material are added to a liquid or slurry-like substance in which a binder or a dispersion stabilizer is dissolved or dispersed in water or an organic solvent to prepare a coating liquid. Good. As the method of dry blending, for example, a positive electrode active material and a lithium compound are premixed using a ball mill or the like, and if necessary, a conductive filler is premixed, and a lithium compound having low conductivity is coated with the conductive filler. You may do. As a result, the lithium compound is easily decomposed in the positive electrode precursor in the lithium doping step described later. When water is used as the solvent of the coating liquid, the coating liquid may become alkaline by adding the lithium compound, so that a pH adjuster may be added if necessary.

The preparation of the coating liquid for the positive electrode precursor is not particularly limited, but preferably a disperser such as a homodisper, a multi-axis disperser, a planetary mixer, or a thin film swirling high-speed mixer is used. Can be done. In order to obtain a coating liquid in a good dispersed state, it is preferable to disperse at a peripheral speed of 1 m / s or more and 50 m / s or less. When the peripheral speed is 1 m / s or more, various materials are preferably dissolved or dispersed. Further, when the peripheral speed is 50 m / s or less, various materials are not destroyed by heat or shearing force due to dispersion, and reaggregation does not occur, which is preferable.
The dispersity of the coating liquid is preferably such that the particle size measured by the grain gauge is 0.1 μm or more and 100 μm or less. The upper limit of the dispersity is more preferably a particle size of 80 μm or less, and further preferably a particle size of 50 μm or less. If the particle size is less than 0.1 μm, the size is smaller than the particle size of various material powders containing the positive electrode active material, and the material is crushed during the preparation of the coating liquid, which is not preferable. Further, when the particle size is 100 μm or less, stable coating can be performed without clogging at the time of discharging the coating liquid or generation of streaks on the coating film.

The viscosity (ηb) of the coating liquid of the positive electrode precursor is preferably 1,000 mPa · s or more and 20,000 mPa · s or less, more preferably 1,500 mPa · s or more and 10,000 mPa · s or less, still more preferably 1. , 700 mPa · s or more and 5,000 mPa · s or less. When the viscosity (ηb) is 1,000 mPa · s or more, liquid dripping during coating film formation is suppressed, and the coating film width and film thickness can be satisfactorily controlled. Further, when the viscosity (ηb) is 20,000 mPa · s or less, the pressure loss in the flow path of the coating liquid when using the coating machine is small and stable coating can be performed, and the coating film thickness is less than the desired one. Can be controlled.
The TI value (thixotropy index value) of the coating liquid is preferably 1.1 or more, more preferably 1.2 or more, and further preferably 1.5 or more. When the TI value is 1.1 or more, the coating film width and the film thickness can be satisfactorily controlled.

The formation of the coating film of the positive electrode precursor is not particularly limited, but a coating machine such as a die coater, a comma coater, a knife coater, or a gravure coating machine can be preferably used. The coating film may be formed by a single-layer coating or a multi-layer coating. In the case of multi-layer coating, the coating liquid composition may be adjusted so that the content of the lithium compound in each layer of the coating film is different. The coating speed is preferably 0.1 m / min or more and 100 m / min or less, more preferably 0.5 m / min or more and 70 m / min or less, and further preferably 1 m / min or more and 50 m / min or less. If the coating speed is 0.1 m / min or more, stable coating can be performed. On the other hand, if the coating speed is 100 m / min or less, sufficient coating accuracy can be ensured.

The drying of the coating film of the positive electrode precursor is not particularly limited, but a drying method such as hot air drying or infrared (IR) drying can be preferably used. The coating film may be dried at a single temperature, or may be dried at different temperatures in multiple stages. Further, the coating film may be dried by combining a plurality of drying methods. The drying temperature is preferably 25 ° C. or higher and 200 ° C. or lower, more preferably 40 ° C. or higher and 180 ° C. or lower, and further preferably 50 ° C. or higher and 160 ° C. or lower. When the drying temperature is 25 ° C. or higher, the solvent in the coating film can be sufficiently volatilized. On the other hand, when the drying temperature is 200 ° C. or lower, cracks in the coating film due to rapid volatilization of the solvent, uneven distribution of the binder due to migration, and oxidation of the positive electrode current collector and the positive electrode active material layer can be suppressed.

The press of the positive electrode precursor is not particularly limited, but a press machine such as a hydraulic press machine or a vacuum press machine can be preferably used. The film thickness, bulk density, and electrode strength of the positive electrode active material layer can be adjusted by the press pressure, the gap, and the surface temperature of the press portion, which will be described later.
The press pressure is preferably 0.5 kN / cm or more and 20 kN / cm or less, more preferably 1 kN / cm or more and 10 kN / cm or less, and further preferably 2 kN / cm or more and 7 kN / cm or less. When the press pressure is 0.5 kN / cm or more, the electrode strength can be sufficiently increased. On the other hand, when the press pressure is 20 kN / cm or less, the positive electrode precursor does not bend or wrinkle, and the desired positive electrode active material layer film thickness and bulk density can be adjusted.
Further, the gap between the press rolls can be set to an arbitrary value according to the film thickness of the positive electrode precursor after drying so as to have a desired film thickness and bulk density of the positive electrode active material layer. Further, the pressing speed can be set to an arbitrary speed at which the positive electrode precursor does not bend or wrinkle.
Further, the surface temperature of the press portion may be room temperature, or the press portion may be heated if necessary. The lower limit of the surface temperature of the pressed portion at the time of heating is preferably a melting point of the binder to be used of minus 60 ° C. or higher, more preferably a melting point of minus 45 ° C. or higher, and further preferably a melting point of minus 30 ° C. or higher. On the other hand, the upper limit of the surface temperature of the pressed portion when heating is preferably the melting point of the binder used plus 50 ° C. or lower, more preferably the melting point plus 30 ° C. or lower, and further preferably the melting point plus 20 ° C. or lower. For example, when PVdF (polyvinylidene fluoride: melting point 150 ° C.) is used as the binder, it is preferable to heat the surface of the pressed portion to 90 ° C. or higher and 200 ° C. or lower, more preferably 105 ° C. or higher and 180 ° C. or lower, and further. It is preferable to heat the surface of the press portion to 120 ° C. or higher and 170 ° C. or lower. When a styrene-butadiene copolymer (melting point 100 ° C.) is used as the binder, the surface of the pressed portion is preferably heated to 40 ° C. or higher and 150 ° C. or lower, more preferably 55 ° C. or higher and 130 ° C. or lower. More preferably, the surface of the pressed portion is heated to 70 ° C. or higher and 120 ° C. or lower.

The melting point of the binder can be determined from the endothermic peak position of DSC (Differential Scanning Calorimetry, differential scanning calorimetry). For example, using a differential scanning calorimeter "DSC7" manufactured by PerkinElmer, 10 mg of sample resin is set in a measurement cell, and the temperature rises from 30 ° C. to 250 ° C. at a heating rate of 10 ° C./min in a nitrogen gas atmosphere. The temperature is raised, and the endothermic peak temperature in the temperature raising process becomes the melting point.
Further, the press may be performed a plurality of times while changing the conditions of the press pressure, the gap, the speed, and the surface temperature of the press portion.

The film thickness of the positive electrode active material layer is preferably 20 μm or more and 200 μm or less per one side of the positive electrode current collector, more preferably 25 μm or more and 100 μm or less per one side, and further preferably 30 μm or more and 80 μm or less. When this film thickness is 20 μm or more, a sufficient charge / discharge capacity can be developed. On the other hand, when this film thickness is 200 μm or less, the ion diffusion resistance in the electrode can be kept low. Therefore, sufficient output characteristics can be obtained, and the cell volume can be reduced, so that the energy density can be increased. The upper and lower limits of the film thickness range of the positive electrode active material layer can be arbitrarily combined. The film thickness of the positive electrode active material layer when the current collector has through holes or irregularities refers to the average value of the film thickness per side of the portion of the current collector that does not have through holes or irregularities.

[Positive electrode]
The bulk density of the positive electrode active material layer in the positive electrode after the lithium doping step described later is preferably 0.25 g / cm ³ or more, more preferably 0.30 g / cm ³ or more and 1.3 g / cm ³ or less. Is. When the bulk density of the positive electrode active material layer is 0.25 g / cm ³ or more, a high energy density can be exhibited and the miniaturization of the power storage element can be achieved. On the other hand, when the bulk density is 1.3 g / cm ³ or less, the electrolytic solution is sufficiently diffused in the pores in the positive electrode active material layer, and high output characteristics can be obtained.

｛式（１）中、Ｒ^１は、炭素数１〜４のアルキレン基、又は炭素数１〜４のハロゲン化アルキレン基であり、Ｘ^１、Ｘ^２はそれぞれ独立に−（ＣＯＯ）_ｎ（ここで、ｎは０又は１である。）である。｝

｛式（２）中、Ｒ^１は、炭素数１〜４のアルキレン基、又は炭素数１〜４のハロゲン化アルキレン基であり、Ｒ^２は水素、炭素数１〜１０のアルキル基、炭素数１〜１０のモノ若しくはポリヒドロキシアルキル基、炭素数２〜１０のアルケニル基、炭素数２〜１０のモノ又はポリヒドロキシアルケニル基、炭素数３〜６のシクロアルキル基、及びアリール基からなる群から選択される基であり、Ｘ^１、Ｘ^２はそれぞれ独立に−（ＣＯＯ）_ｎ（ここで、ｎは０又は１である。）である。｝

｛式（３）中、Ｒ^１は、炭素数１〜４のアルキレン基、又は炭素数１〜４のハロゲン化アルキレン基であり、Ｒ^２、Ｒ^３はそれぞれ独立に水素、炭素数１〜１０のアルキル基、炭素数１〜１０のモノ若しくはポリヒドロキシアルキル基、炭素数２〜１０のアルケニル基、炭素数２〜１０のモノ又はポリヒドロキシアルケニル基、炭素数３〜６のシクロアルキル基、及びアリール基からなる群から選択される基であり、Ｘ^１、Ｘ^２はそれぞれ独立に−（ＣＯＯ）_ｎ（ここで、ｎは０又は１である。）である。｝ [Compound in positive electrode active material layer]
The positive electrode active material layer according to the present invention contains one or more compounds selected from the following formulas (1) to (3) at 1.60 × 10 ^-4 mol / g to 100 × per unit mass of the positive electrode material layer. It preferably contains 10 ^-4 mol / g.

{In formula (1), R ¹ is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms, and X ¹ and X ² are independently − (COO) _n (here). And n is 0 or 1). }

{In the formula (2), R ¹ is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms, and R ² is hydrogen, an alkyl group having 1 to 10 carbon atoms, and a carbon number of carbon atoms. From the group consisting of 1 to 10 mono or polyhydroxyalkyl groups, alkenyl groups with 2 to 10 carbon atoms, mono or polyhydroxyalkenyl groups with 2 to 10 carbon atoms, cycloalkyl groups with 3 to 6 carbon atoms, and aryl groups. It is a group to be selected, and X ¹ and X ² are independently − (COO) _n (where n is 0 or 1). }

{In the formula (3), R ¹ is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms, and R ² and R ³ are independently hydrogen and 1 to 10 carbon atoms, respectively. Alkyl group, mono or polyhydroxyalkyl group having 1 to 10 carbon atoms, alkenyl group having 2 to 10 carbon atoms, mono or polyhydroxyalkenyl group having 2 to 10 carbon atoms, cycloalkyl group having 3 to 6 carbon atoms, and It is a group selected from the group consisting of aryl groups, and X ¹ and X ² are independently − (COO) _n (where n is 0 or 1). }

In the formula (1), R ¹ is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms, and X ¹ and X ² are independently − (COO) _n (here). , N is 0 or 1.).
Particularly preferred compounds are
It is a compound represented by LiOC ₂ H ₄ OLi, LiOC ₃ H ₆ OLi, LiOC ₂ H ₄ OCOOLi, LiOCOOC ₃ H ₆ OLi, LiOCOOC ₂ H ₄ OCOOLi and LiOCOOC ₃ H ₆ OCOOLi.

In the formula (2), R ¹ is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms, and R ² is hydrogen, an alkyl group having 1 to 10 carbon atoms, and 1 carbon atom. Select from the group consisting of a mono or polyhydroxyalkyl group having 10 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a mono or polyhydroxyalkenyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, and an aryl group. X ¹ and X ² are independently − (COO) _n (where n is 0 or 1).
Particularly preferred compounds are
LiOC ₂ H ₄ OH, LiOC ₃ H ₆ OH, LiOC ₂ H ₄ OCOOH, LiOC ₃ H ₆ OCOOH, LiOCOC ₂ H ₄ OCOOH, LiOCOC ₃ H ₆ OCOOH, LiOC ₂ H ₄ OCH ₃ , LiOC ₃ H ₆ OCH _{3 LiOC 2 H 4 OCOOCH 3, LiOC} 3 H 6 OCOOCH 3, LiOCOOC 2 H 4 OCOOCH 3, LiOCOOC 3 H 6 OCOOCH 3, LiOC 2 H 4 OC 2 H 5, LiOC 3 H 6 OC 2 H 5, LiOC 2 H 4 It is a compound represented by OCOC ₂ H ₅ , LiOC ₃ H ₆ OCOC ₂ H ₅ , LiOCOC ₂ H ₄ OCOC ₂ H ₅ , LiOCOC ₃ H ₆ OCOC ₂ H ₅ .

In the formula (3), R ¹ is an alkylene group having 1 to 4 carbon atoms or a halogenated alkylene group having 1 to 4 carbon atoms, and R ² and R ³ are independently hydrogen and 1 to 10 carbon atoms, respectively. Alkyl groups, mono or polyhydroxyalkyl groups with 1 to 10 carbon atoms, alkenyl groups with 2 to 10 carbon atoms, mono or polyhydroxyalkenyl groups with 2 to 10 carbon atoms, cycloalkyl groups with 3 to 6 carbon atoms, and aryl It is a group selected from the group consisting of groups, and X ¹ and X ² are independently − (COO) _n (where n is 0 or 1).
Particularly preferred compounds are
HOC ₂ H ₄ OH, HOC ₃ H ₆ OH, HOC ₂ H ₄ OCOOH, HOC ₃ H ₆ OCOOH, HOCOC ₂ H ₄ OCOOH, HOCOC ₃ H ₆ OCOOH, HOC ₂ H ₄ OCH ₃ , HOC ₃ H ₆ OCH _{3 HOC 2 H 4 OCOOCH 3, HOC} 3 H 6 OCOOCH 3, HOCOOC 2 H 4 OCOOCH 3, HOCOOC 3 H 6 OCOOCH 3, HOC 2 H 4 OC 2 H 5, HOC 3 H 6 OC 2 H 5, HOC 2 H 4 OCOOC ₂ H ₅ , HOC ₃ H ₆ OCOOC ₂ H ₅ , HOCOOC ₂ H ₄ OCOOC ₂ H ₅ , HOCOOC ₃ H ₆ OCOOC ₂ H ₅ , CH ₃ OC ₂ H ₄ OCH ₃ , CH ₃ OC ₃ H ₆ OCH _{3 CH 3 OC 2 H 4 OCOOCH 3} , CH 3 OC 3 H 6 OCOOCH 3, CH 3 OCOOC 2 H 4 OCOOCH 3, CH 3 OCOOC 3 H 6 OCOOCH 3, CH 3 OC 2 H 4 OC 2 H 5, CH 3 OC ₃ H ₆ OC ₂ H ₅ , CH ₃ OC ₂ H ₄ OCOC ₂ H ₅ , CH ₃ OC ₃ H ₆ OCOC ₂ H ₅ , CH ₃ OCOC ₂ H ₄ OCOC ₂ H ₅ , CH ₃ OCOC ₃ H ₆ OCOC ₂ H ₅ , C ₂ H ₅ OC ₂ H ₄ OC ₂ H ₅ , C ₂ H ₅ OC ₃ H ₆ OC ₂ H ₅ , C ₂ H ₅ OC ₂ H ₄ OCOC ₂ H ₅ , C ₂ H ₅ OC ₃ H ₆ OCOC ₂ H ₅ , C ₂ H ₅ OCOC ₂ H ₄ OCOC ₂ H ₅ , C ₂ H ₅ OCOC ₃ H ₆ OCOC ₂ H ₅
It is a compound represented by.

As a method for incorporating the above-mentioned compound in the positive electrode active material layer in the present invention, for example,
A method of mixing the compound with the positive electrode active material layer,
A method of adsorbing the compound on the positive electrode active material layer,
Examples thereof include a method of electrochemically precipitating the compound on the positive electrode active material layer.
Above all, a positive electrode active material layer is contained in a non-aqueous electrolytic solution that can be decomposed to produce these compounds, and the decomposition reaction of the precursor in the step of producing a power storage element is utilized. A method of depositing the compound inside is preferable.

As the precursor for forming the compound, it is preferable to use at least one organic solvent selected from ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate and fluoroethylene carbonate, and ethylene carbonate and propylene carbonate are used. It is more preferable to do so.

Here, the total amount of the compound is preferably 1.60 × 10 ^-4 mol / g or more, and preferably 5.0 × 10 ^-4 mol / g or more, per unit mass of the positive electrode active material layer. Is more preferable. When the total amount of the compound is 1.60 × 10 ^-4 mol / g or more per unit mass of the positive electrode active material layer, the non-aqueous electrolyte solution does not come into contact with the positive electrode active material, and the non-aqueous electrolyte solution is oxidatively decomposed. It is possible to suppress the generation of gas and suppress the increase in resistance.
The total amount of the compound is preferably 100 × 10 ^-4 mol / g or less, more preferably 80 × 10 ^-4 mol / g or less, and more preferably 70 × 10 ^-4 mol / g or less, per unit mass of the positive electrode active material layer. Most preferably, it is × 10 ^-4 mol / g or less. When the total amount of the compound is 100 × 10 ^-4 mol / g or less per unit mass of the positive electrode active material layer, high input / output characteristics can be exhibited without inhibiting the diffusion of Li ions at the positive electrode interface. ..

[Negative electrode]
The negative electrode has a negative electrode current collector and a negative electrode active material layer existing on one side or both sides thereof.

[Negative electrode active material layer]
The negative electrode active material layer contains a negative electrode active material that can occlude and release lithium ions. In addition to this, if necessary, an optional component such as a conductive filler, a binder, and a dispersion stabilizer may be contained.

[Negative electrode active material]
As the negative electrode active material, a substance capable of storing and releasing lithium ions can be used. Specific examples thereof include carbon materials, titanium oxides, silicon, silicon oxides, silicon alloys, silicon compounds, tin and tin compounds. The content of the carbon material with respect to the total amount of the negative electrode active material is preferably 50% by mass or more, and more preferably 70% by mass or more. The content of the carbon material may be 100% by mass, but from the viewpoint of obtaining a good effect by using other materials in combination, for example, it is preferably 90% by mass or less, and preferably 80% by mass or less.

The negative electrode active material is preferably doped with lithium ions. In the present specification, the lithium ions doped in the negative electrode active material mainly include three forms.
The first form is lithium ions that are occluded as a design value in the negative electrode active material before the non-aqueous lithium-type power storage element is manufactured.
The second form is lithium ions occluded in the negative electrode active material when a non-aqueous lithium-type power storage element is manufactured and shipped.
The third form is lithium ions occluded in the negative electrode active material after the non-aqueous lithium-type power storage element is used as a device.
By doping the negative electrode active material with lithium ions, it is possible to satisfactorily control the capacity and operating voltage of the obtained non-aqueous lithium-type power storage element.

Examples of the carbon material include non-graphitizable carbon materials; easily graphitizable carbon materials; carbon black; carbon nanoparticles; activated carbon; artificial graphite; natural graphite; graphitized mesophase carbon globules; graphite whiskers; polyacene-based substances. Amorphous carbonaceous materials such as; petroleum-based pitches, coal-based pitches, carbonaceous materials such as mesocarbon microbeads, coke, synthetic resins (eg, phenolic resins, etc.) Carbonated materials obtained by heat treatment of precursors; full Thermal decomposition products of frill alcohol resin or novolak resin; fullerene; carbon nanophones; and composite carbon materials thereof can be mentioned.

Among these, from the viewpoint of lowering the resistance of the negative electrode, heat treatment is performed in a state where one or more of the carbon materials (hereinafter, also referred to as a base material) and the carbonaceous material precursor coexist, and the base material and the carbon are coexisted. A composite carbon material obtained by combining a carbon material derived from a quality material precursor is preferable. The carbonaceous material precursor is not particularly limited as long as it becomes the carbonaceous material by heat treatment, but a petroleum-based pitch or a coal-based pitch is particularly preferable. The substrate and the carbonaceous material precursor may be mixed at a temperature higher than the melting point of the carbonaceous material precursor before the heat treatment. The heat treatment temperature may be any temperature as long as the component generated by volatilization or thermal decomposition of the carbonaceous material precursor to be used becomes the carbonaceous material, but is preferably 400 ° C. or higher and 2500 ° C. or lower, more preferably 500 ° C. It is 2000 ° C. or lower, more preferably 550 ° C. or higher and 1500 ° C. or lower. The atmosphere in which the heat treatment is performed is not particularly limited, but a non-oxidizing atmosphere is preferable.

Preferred examples of the composite carbon material are composite carbon materials 1 and 2 described later. Either of these may be selected and used, or both of them may be used in combination.

[Composite carbon material 1]
The composite carbon material 1 is the composite carbon material using one or more carbon materials having a BET specific surface area of 100 m ² / g or more and 3000 m ² / g or less as the base material. The base material is not particularly limited, but activated carbon, carbon black, template porous carbon, high specific surface area graphite, carbon nanoparticles and the like can be preferably used.

The BET specific surface area of the composite carbon material 1 is preferably 100 m ² / g or more and 1,500 m ² / g or less, more preferably 150 m ² / g or more and 1,100 m ² / g or less, and further preferably 180 m ² / g or more and 550 m. ^{It is 2} / g or less. When the BET specific surface area is 100 m ² / g or more, the pores can be appropriately retained and the diffusion of lithium ions becomes good, so that high input / output characteristics can be exhibited. On the other hand, when it is 1,500 m ² / g or less, the charge / discharge efficiency of lithium ions is improved, so that the cycle durability is not impaired.

The mass ratio of the carbonaceous material to the base material in the composite carbon material 1 is preferably 10% by mass or more and 200% by mass or less. This mass ratio is preferably 12% by mass or more and 180% by mass or less, more preferably 15% by mass or more and 160% by mass or less, and particularly preferably 18% by mass or more and 150% by mass or less. When the mass ratio of the carbonaceous material is 10% by mass or more, the micropores of the base material can be appropriately filled with the carbonic material, and the charge / discharge efficiency of lithium ions is improved, which is good. Cycle durability can be shown. Further, when the mass ratio of the carbonaceous material is 200% by mass or less, the pores can be appropriately retained and the diffusion of lithium ions becomes good, so that high input / output characteristics can be exhibited.

The doping amount of lithium ions per unit mass of the composite carbon material 1 is preferably 530 mAh / g or more and 2,500 mAh / g or less. It is more preferably 620 mAh / g or more and 2,100 mAh / g or less, further preferably 760 mAh / g or more and 1,700 mAh / g or less, and particularly preferably 840 mAh / g or more and 1,500 mAh / g or less.
By doping with lithium ions, the negative electrode potential is lowered. Therefore, when the negative electrode containing the lithium ion-doped composite carbon material 1 is combined with the positive electrode, the voltage of the non-aqueous lithium-type power storage element becomes high and the utilization capacity of the positive electrode becomes large. Therefore, the capacity and energy density of the obtained non-aqueous lithium-type power storage element are increased.
When the doping amount is 530 mAh / g or more, the lithium ions are well doped in the irreversible sites that cannot be desorbed once the lithium ions in the composite carbon material 1 are inserted, and the composite carbon material 1 with respect to the desired lithium amount is further doped. The amount of can be reduced. Therefore, the film thickness of the negative electrode can be reduced, and a high energy density can be obtained. As the doping amount increases, the negative electrode potential decreases, and the input / output characteristics, energy density, and durability improve.
On the other hand, if the doping amount is 2,500 mAh / g or less, there is no possibility that side effects such as precipitation of lithium metal will occur.

Hereinafter, as a preferable example of the composite carbon material 1, the composite carbon material 1a using activated carbon as the base material will be described.
The composite carbon material 1a has a mesopore amount of Vm1 (cc / g) derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method, and a micropore amount derived from pores having a diameter of less than 20 Å calculated by the MP method. When Vm2 (cc / g), 0.010 ≦ Vm1 ≦ 0.300 and 0.001 ≦ Vm2 ≦ 0.650 are preferable.
The mesopore amount Vm1 is more preferably 0.010 ≦ Vm1 ≦ 0.225, and further preferably 0.010 ≦ Vm1 ≦ 0.200. The micropore amount Vm2 is more preferably 0.001 ≦ Vm2 ≦ 0.200, further preferably 0.001 ≦ Vm2 ≦ 0.150, and particularly preferably 0.001 ≦ Vm2 ≦ 0.100.
When the mesopore amount Vm1 is 0.300 cc / g or less, the BET specific surface area can be increased, the doping amount of lithium ions can be increased, and the bulk density of the negative electrode can be increased. As a result, the negative electrode can be thinned. Further, when the micropore amount Vm2 is 0.650 cc / g or less, high charge / discharge efficiency for lithium ions can be maintained. On the other hand, when the mesopore amount Vm1 and the micropore amount Vm2 are equal to or higher than the lower limit (0.010 ≦ Vm1, 0.001 ≦ Vm2), high input / output characteristics can be obtained.

The BET specific surface area of the composite carbon material 1a is preferably 100 m ² / g or more and 1,500 m ² / g or less. It is more preferably 150 m ² / g or more and 1,100 m ² / g or less, and further preferably 180 m ² / g or more and 550 m ² / g or less. When the BET specific surface area is 100 m ² / g or more, the pores can be appropriately retained, and the diffusion of lithium ions becomes good, so that high input / output characteristics can be exhibited. Moreover, since the doping amount of lithium ions can be increased, the negative electrode can be thinned. On the other hand, when it is 1,500 m ² / g or less, the charge / discharge efficiency of lithium ions is improved, so that the cycle durability is not impaired.

The average pore diameter of the composite carbon material 1a is preferably 20 Å or more, more preferably 25 Å or more, and even more preferably 30 Å or more, from the viewpoint of providing high input / output characteristics. On the other hand, from the viewpoint of increasing the energy density, the average pore diameter is preferably 65 Å or less, and more preferably 60 Å or less.

The average particle size of the composite carbon material 1a is preferably 1 μm or more and 10 μm or less. The lower limit is more preferably 2 μm or more, still more preferably 2.5 μm or more. The upper limit is more preferably 6 μm or less, still more preferably 4 μm or less. Good durability is maintained when the average particle size is 1 μm or more and 10 μm or less.

The atomic number ratio (H / C) of hydrogen atom / carbon atom of the composite carbon material 1a is preferably 0.05 or more and 0.35 or less, and more preferably 0.05 or more and 0.15 or less. .. When the H / C is 0.35 or less, the structure of the carbonaceous material adhered to the surface of the activated carbon (typically, the polycyclic aromatic conjugated structure) is well developed and the capacity (energy). Density) and charge / discharge efficiency increase. On the other hand, when the H / C is 0.05 or more, carbonization does not proceed excessively, so that a good energy density can be obtained. H / C is measured by an elemental analyzer.

The composite carbon material 1a has an amorphous structure derived from the activated carbon of the base material, and at the same time, has a crystal structure mainly derived from the adhered carbonaceous material. According to the X-ray wide-angle diffraction method, the composite carbon material 1a has a (002) plane spacing d002 of 3.60 Å or more and 4.00 Å or less, and crystallites in the c-axis direction obtained from the half-value width of this peak. The size Lc is preferably 8.0 Å or more and 20.0 Å or less, d002 is 3.60 Å or more and 3.75 Å or less, and the crystallite size Lc in the c-axis direction obtained from the half-value width of this peak is 11. More preferably, it is 0 Å or more and 16.0 Å or less.

The activated carbon used as the base material of the composite carbon material 1a is not particularly limited as long as the obtained composite carbon material 1a exhibits desired properties. For example, commercially available products obtained from various raw materials such as petroleum-based, coal-based, plant-based, and polymer-based can be used. In particular, it is preferable to use activated carbon powder having an average particle size of 1 μm or more and 15 μm or less. The average particle size is more preferably 2 μm or more and 10 μm or less.

In order to obtain the composite carbon material 1a having the pore distribution range specified in the present embodiment, the pore distribution of the activated carbon used for the base material is important.
In the activated carbon, the amount of mesopores derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method is V1 (cc / g), and the amount of micropores derived from pores having a diameter of less than 20 Å calculated by the MP method. When V2 (cc / g) is set, it is preferable that 0.050 ≦ V1 ≦ 0.500, 0.005 ≦ V2 ≦ 1.000, and 0.2 ≦ V1 / V2 ≦ 20.0.

Regarding the mesopore amount V1, 0.050 ≦ V1 ≦ 0.350 is more preferable, and 0.100 ≦ V1 ≦ 0.300 is even more preferable. Regarding the micropore amount V2, 0.005 ≦ V2 ≦ 0.850 is more preferable, and 0.100 ≦ V2 ≦ 0.800 is even more preferable. Regarding the ratio of mesopore amount / micropore amount, 0.22 ≦ V1 / V2 ≦ 15.0 is more preferable, and 0.25 ≦ V1 / V2 ≦ 10.0 is even more preferable. When the mesopore amount V1 of the activated carbon is 0.500 or less and the micropore amount V2 is 1.000 or less, an appropriate amount of carbonaceous material is obtained in order to obtain the pore structure of the composite carbon material 1a in the present embodiment. Since it is sufficient to adhere the material, it becomes easy to control the pore structure. On the other hand, when the mesopore amount V1 of the activated carbon is 0.050 or more, the micropore amount V2 is 0.005 or more, V1 / V2 is 0.2 or more, and V1 / V2 is 20.0. The structure can be easily obtained even in the following cases.

The carbonaceous material precursor used as the raw material of the composite carbon material 1a is a solid, liquid, or solvent-soluble organic material capable of adhering the carbonic material to the activated carbon by heat treatment. .. Examples of the carbonaceous material precursor include pitch, mesocarbon microbeads, coke, synthetic resin (for example, phenol resin, etc.) and the like. Among these carbonaceous material precursors, it is preferable to use an inexpensive pitch in terms of manufacturing cost. Pitches are roughly divided into petroleum-based pitches and coal-based pitches. Examples of petroleum-based pitches include distillation residue of crude oil, fluid contact decomposition residue (decant oil, etc.), bottom oil derived from thermal crackers, ethylene tar obtained during naphtha cracking, and the like.

When the above pitch is used, the pitch is heat-treated in the coexistence with the activated carbon, and the volatile component or the pyrolysis component of the pitch is thermally reacted on the surface of the activated carbon to coat the activated carbon with a carbonaceous material. Material 1a is obtained. In this case, the adhesion of the volatile component or the thermal decomposition component of the pitch into the activated carbon pores proceeds at a temperature of about 200 to 500 ° C., and the reaction in which the adhered component becomes a carbonaceous material proceeds at 400 ° C. or higher. To do. The peak temperature (maximum temperature reached) during the heat treatment is appropriately determined depending on the characteristics of the obtained composite carbon material 1a, the thermal reaction pattern, the thermal reaction atmosphere, etc., but is preferably 400 ° C. or higher, more preferably 400 ° C. or higher. Is 450 ° C. to 1,000 ° C., more preferably about 500 to 800 ° C. The time for maintaining the peak temperature during the heat treatment is preferably 30 minutes to 10 hours, more preferably 1 hour to 7 hours, and further preferably 2 hours to 5 hours. For example, when heat-treating at a peak temperature of about 500 to 800 ° C. for 2 hours to 5 hours, it is considered that the carbonaceous material adhered to the surface of the activated carbon is a polycyclic aromatic hydrocarbon. ..

The softening point of the pitch used is preferably 30 ° C. or higher and 250 ° C. or lower, and more preferably 60 ° C. or higher and 130 ° C. or lower. A pitch having a softening point of 30 ° C. or higher does not hinder handleability and can be charged with high accuracy. The pitch at which the softening point is 250 ° C. or lower contains a large amount of relatively low molecular weight compounds, and therefore, when the pitch is used, even fine pores in the activated carbon can be adhered.
As a specific method for producing the above-mentioned composite carbon material 1a, for example, the activated carbon is heat-treated in an inert atmosphere containing a hydrocarbon gas volatilized from the carbon material precursor, and the carbon material is covered with a vapor phase. There is a method of dressing. Further, a method in which the activated carbon and the carbonaceous material precursor are mixed in advance and heat-treated, or a method in which the carbonic material precursor dissolved in a solvent is applied to the activated carbon, dried, and then heat-treated is also possible.

It is preferable that the mass ratio of the carbonaceous material to the activated carbon in the composite carbon material 1a is 10% by mass or more and 100% by mass or less. This mass ratio is preferably 15% by mass or more and 80% by mass or less. When the mass ratio of the carbonaceous material is 10% by mass or more, the micropores of the activated carbon can be appropriately filled with the carbonic material, and the charge / discharge efficiency of lithium ions is improved, so that the cycle durability is improved. The sex is not impaired. Further, when the mass ratio of the carbonaceous material is 100% by mass or less, the pores of the composite carbon material 1a are appropriately retained and the specific surface area is maintained large. Therefore, from the result that the doping amount of lithium ions can be increased, high output density and high durability can be maintained even if the negative electrode is thinned.

[Composite carbon material 2]
The composite carbon material 2 is the composite carbon material using one or more carbon materials having a BET specific surface area of 0.5 m ² / g or more and 80 m ² / g or less as the base material. The base material is not particularly limited, but natural graphite, artificial graphite, low crystal graphite, hard carbon, soft carbon, carbon black and the like can be preferably used.

BET specific surface area of the composite carbon material 2, ^{1 m} 2 / g or more ^{50 m} 2 / g or less, more preferably 1.5 m ² / g or more ^{40 m} 2 / g or less, more preferably ^2m 2 / g or more ^{25 m} 2 / It is less than or equal to g. When the BET specific surface area is 1 m ² / g or more, a sufficient reaction field with lithium ions can be secured, so that high input / output characteristics can be exhibited. On the other hand, when it is 50 m ² / g or less, the charge / discharge efficiency of lithium ions is improved and the decomposition reaction of the non-aqueous electrolyte solution during charge / discharge is suppressed, so that high cycle durability can be exhibited.

The average particle size of the composite carbon material 2 is preferably 1 μm or more and 10 μm or less. The average particle size is more preferably 2 μm or more and 8 μm or less, and further preferably 3 μm or more and 6 μm or less. When the average particle size is 1 μm or more, the charge / discharge efficiency of lithium ions can be improved, so that high cycle durability can be exhibited. On the other hand, if it is 10 μm or less, the reaction area between the composite carbon material 2 and the non-aqueous electrolytic solution increases, so that high input / output characteristics can be exhibited.

The mass ratio of the carbonaceous material to the base material in the composite carbon material 2 is preferably 1% by mass or more and 30% by mass or less. This mass ratio is more preferably 1.2% by mass or more and 25% by mass or less, and further preferably 1.5% by mass or more and 20% by mass or less. When the mass ratio of the carbonaceous material is 1% or more by mass, the carbonaceous material can sufficiently increase the reaction sites with lithium ions, and the desolvation of lithium ions becomes easy, so that high input / output characteristics can be obtained. Can be shown. On the other hand, when the mass ratio of the carbonaceous material is 20% by mass or less, the diffusion of lithium ions between the carbonic material and the base material in the solid can be well maintained, so that high input / output characteristics can be exhibited. You can. Moreover, since the charge / discharge efficiency of lithium ions can be improved, high cycle durability can be exhibited.

The doping amount of lithium ions per unit mass of the composite carbon material 2 is preferably 50 mAh / g or more and 700 mAh / g or less. It is more preferably 70 mAh / g or more and 650 mAh / g or less, further preferably 90 mAh / g or more and 600 mAh / g or less, and particularly preferably 100 mAh / g or more and 550 mAh / g or less.
By doping with lithium ions, the negative electrode potential is lowered. Therefore, when the negative electrode containing the lithium ion-doped composite carbon material 2 is combined with the positive electrode, the voltage of the non-aqueous lithium-type power storage element becomes high and the utilization capacity of the positive electrode becomes large. Therefore, the capacity and energy density of the obtained non-aqueous lithium-type power storage element are increased.
When the doping amount is 50 mAh / g or more, lithium ions are satisfactorily doped even at irreversible sites that cannot be desorbed once the lithium ions in the composite carbon material 2 are inserted, so that a high energy density can be obtained. As the doping amount increases, the negative electrode potential decreases, and the input / output characteristics, energy density, and durability improve.
On the other hand, if the doping amount is 700 mAh / g or less, there is no possibility that side effects such as precipitation of lithium metal will occur.

Hereinafter, as a preferable example of the composite carbon material 2, the composite carbon material 2a using a graphite material as the base material will be described.
The average particle size of the composite carbon material 2a is preferably 1 μm or more and 10 μm or less. The average particle size is more preferably 2 μm or more and 8 μm or less, and further preferably 3 μm or more and 6 μm or less. When the average particle size is 1 μm or more, the charge / discharge efficiency of lithium ions can be improved, so that high cycle durability can be exhibited. On the other hand, if it is 10 μm or less, the reaction area between the composite carbon material 2a and the non-aqueous electrolytic solution increases, so that high input / output characteristics can be exhibited.

The BET specific surface area of the composite carbon material 2a is preferably 1 m ² / g or more and 20 m ² / g or less. More preferably, it is 1 m ² / g or more and 15 m ² / g or less. When the BET specific surface area is 1 m ² / g or more, a sufficient reaction field with lithium ions can be secured, so that high input / output characteristics can be exhibited. On the other hand, when it is 20 m ² / g or less, the charge / discharge efficiency of lithium ions is improved and the decomposition reaction of the non-aqueous electrolyte solution during charge / discharge is suppressed, so that high cycle durability can be exhibited.

The graphite material used as the base material is not particularly limited as long as the obtained composite carbon material 2a exhibits desired properties. For example, artificial graphite, natural graphite, graphitized mesophase carbon globules, graphite whiskers and the like can be used. The average particle size of the graphite material is preferably 1 μm or more and 10 μm or less, and more preferably 2 μm or more and 8 μm or less.

The carbonaceous material precursor used as the raw material of the composite carbon material 2a is a solid, liquid, or solvent-soluble organic material capable of combining the carbonic material with the graphite material by heat treatment. .. Examples of the carbonaceous material precursor include pitch, mesocarbon microbeads, coke, synthetic resin (for example, phenol resin, etc.) and the like. Among these carbonaceous material precursors, it is preferable to use an inexpensive pitch in terms of manufacturing cost. Pitches are roughly divided into petroleum-based pitches and coal-based pitches. Examples of petroleum-based pitches include distillation residue of crude oil, fluid contact decomposition residue (decant oil, etc.), bottom oil derived from thermal crackers, ethylene tar obtained during naphtha cracking, and the like.

The mass ratio of the carbonaceous material to the graphite material in the composite carbon material 2a is preferably 1% by mass or more and 10% by mass or less. This mass ratio is more preferably 1.2% by mass or more and 8% by mass or less, further preferably 1.5% by mass or more and 6% by mass or less, and particularly preferably 2% by mass or more and 5% by mass or less. When the mass ratio of the carbonaceous material is 1% by mass or more, the carbonaceous material can sufficiently increase the reaction sites with lithium ions and desolvate the lithium ions easily, so that high input / output characteristics can be obtained. Can be shown. On the other hand, when the mass ratio of the carbonaceous material is 20% by mass or less, the diffusion of lithium ions between the carbonic material and the graphite material in the solid can be well maintained, so that high input / output characteristics can be exhibited. You can. Moreover, since the charge / discharge efficiency of lithium ions can be improved, high cycle durability can be exhibited.

[Arbitrary component]
If necessary, the negative electrode active material layer in the present invention may contain an optional component such as a conductive filler, a binder, and a dispersion stabilizer in addition to the negative electrode active material.
The type of the conductive filler is not particularly limited, and examples thereof include acetylene black, ketjen black, and vapor-grown carbon fiber. The amount of the conductive filler used is preferably 0 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the negative electrode active material. It is more preferably 0 parts by mass or more and 20 parts by mass or less, and further preferably 0 parts by mass or more and 15 parts by mass or less.

The binder is not particularly limited, but for example, PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), polyimide, latex, styrene-butadiene copolymer, fluororubber, acrylic copolymer and the like. Can be used. The amount of the binder used is preferably 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the negative electrode active material. It is more preferably 2 parts by mass or more and 27 parts by mass or less, and further preferably 3 parts by mass or more and 25 parts by mass or less. When the amount of the binder is 1 part by mass or more, sufficient electrode strength is exhibited. On the other hand, when the amount of the binder is 30 parts by mass or less, high input / output characteristics are exhibited without inhibiting the entry and exit of lithium ions into the negative electrode active material.

The dispersion stabilizer is not particularly limited, but for example, PVP (polyvinylpyrrolidone), PVA (polyvinyl alcohol), a cellulose derivative and the like can be used. The amount of the dispersion stabilizer used is preferably 0 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the negative electrode active material. When the amount of the dispersion stabilizer is 10 parts by mass or less, high input / output characteristics are exhibited without inhibiting the entry and exit of lithium ions into the negative electrode active material.

[Negative electrode current collector]
The material constituting the negative electrode current collector in the present invention is preferably a metal foil having high electron conductivity and not deteriorating due to elution into a non-aqueous electrolyte solution and reaction with an electrolyte or ions. Such metal foil is not particularly limited, and examples thereof include aluminum foil, copper foil, nickel foil, and stainless steel foil. Copper foil is preferable as the negative electrode current collector in the non-aqueous lithium power storage device of the present embodiment.
The metal foil may be an ordinary metal foil having no irregularities or through holes, a metal foil having irregularities subjected to embossing, chemical etching, electrolytic precipitation, blasting, etc., expanded metal, punching metal, etc. , A metal foil having through holes such as an etching foil may be used.
The thickness of the negative electrode current collector is not particularly limited as long as the shape and strength of the negative electrode can be sufficiently maintained, but is preferably 1 to 100 μm, for example.

[Manufacturing of negative electrode]
The negative electrode has a negative electrode active material layer on one side or both sides of the negative electrode current collector. In a typical embodiment, the negative electrode active material layer is fixed to the negative electrode current collector.
The negative electrode can be manufactured by a technique for manufacturing electrodes in known lithium ion batteries, electric double layer capacitors and the like. For example, various materials including a negative electrode active material are dispersed or dissolved in water or an organic solvent to prepare a slurry coating liquid, and this coating liquid is applied to one or both sides of a negative electrode current collector. A negative electrode can be obtained by forming a coating film and drying it. Further, the obtained negative electrode may be pressed to adjust the film thickness and bulk density of the negative electrode active material layer. Alternatively, it is also possible to dry-mix various materials including the negative electrode active material without using a solvent, press-mold the obtained mixture, and then attach it to the negative electrode current collector using a conductive adhesive. is there.

The coating liquid is prepared by dry-blending a part or all of various material powders including the negative electrode active material, and then water or an organic solvent and / or a liquid in which a binder or a dispersion stabilizer is dissolved or dispersed therein. A slurry-like substance may be added to prepare the mixture. Further, various material powders containing a negative electrode active material may be added to the liquid or slurry-like substance in which a binder or a dispersion stabilizer is dissolved or dispersed in water or an organic solvent. Although the adjustment of the coating liquid is not particularly limited, a homodisper, a multi-axis disperser, a planetary mixer, a disperser such as a thin film swirl type high-speed mixer, or the like can be preferably used. In order to obtain a coating liquid in a good dispersed state, it is preferable to disperse at a peripheral speed of 1 m / s or more and 50 m / s or less. A peripheral speed of 1 m / s or more is preferable because various materials are satisfactorily dissolved or dispersed. Further, when it is 50 m / s or less, various materials are not destroyed by heat or shearing force due to dispersion, and reaggregation does not occur, which is preferable.

The viscosity (ηb) of the coating liquid is preferably 1,000 mPa · s or more and 20,000 mPa · s or less. It is more preferably 1,500 mPa · s or more and 10,000 mPa · s or less, and further preferably 1,700 mPa · s or more and 5,000 mPa · s or less. When the viscosity (ηb) is 1,000 mPa · s or more, liquid dripping during coating film formation is suppressed, and the coating film width and film thickness can be satisfactorily controlled. Further, when it is 20,000 mPa · s or less, the pressure loss in the flow path of the coating liquid when using the coating machine is small and stable coating can be performed, and the coating film thickness can be controlled to be less than the desired coating film thickness.
The TI value (thixotropy index value) of the coating liquid is preferably 1.1 or more. It is more preferably 1.2 or more, still more preferably 1.5 or more. When the TI value is 1.1 or more, the coating film width and the film thickness can be satisfactorily controlled.

The formation of the coating film is not particularly limited, but a coating machine such as a die coater, a comma coater, a knife coater, or a gravure coating machine can be preferably used. The coating film may be formed by a single-layer coating or a multi-layer coating. The coating speed is preferably 0.1 m / min or more and 100 m / min or less. It is more preferably 0.5 m / min or more and 70 m / min or less, and further preferably 1 m / min or more and 50 m / min or less. If the coating speed is 0.1 m / min or more, stable coating can be performed. On the other hand, if it is 100 m / min or less, sufficient coating accuracy can be ensured.

The drying of the coating film is not particularly limited, but a drying method such as hot air drying or infrared (IR) drying can be preferably used. The coating film may be dried at a single temperature, or may be dried at different temperatures in multiple stages. Moreover, you may dry by combining a plurality of drying methods. The drying temperature is preferably 25 ° C. or higher and 200 ° C. or lower. It is more preferably 40 ° C. or higher and 180 ° C. or lower, and further preferably 50 ° C. or higher and 160 ° C. or lower. When the drying temperature is 25 ° C. or higher, the solvent in the coating film can be sufficiently volatilized. On the other hand, when the temperature is 200 ° C. or lower, cracks in the coating film due to rapid volatilization of the solvent, uneven distribution of the binder due to migration, and oxidation of the negative electrode current collector and the negative electrode active material layer can be suppressed.

The press of the negative electrode is not particularly limited, but a press machine such as a hydraulic press machine or a vacuum press machine can be preferably used. The film thickness, bulk density, and electrode strength of the negative electrode active material layer can be adjusted by the press pressure, the gap, and the surface temperature of the press portion, which will be described later. The press pressure is preferably 0.5 kN / cm or more and 20 kN / cm or less. It is more preferably 1 kN / cm or more and 10 kN / cm or less, and further preferably 2 kN / cm or more and 7 kN / cm or less. When the press pressure is 0.5 kN / cm or more, the electrode strength can be sufficiently increased. On the other hand, when it is 20 kN / cm or less, the negative electrode does not bend or wrinkle, and the film thickness and bulk density of the negative electrode active material can be adjusted to a desired value. Further, the gap between the press rolls can be set to an arbitrary value according to the film thickness of the negative electrode after drying so as to have a desired film thickness and bulk density of the negative electrode active material layer. Further, the pressing speed can be set to an arbitrary speed at which the negative electrode does not bend or wrinkle. Further, the surface temperature of the pressed portion may be room temperature or may be heated if necessary. The lower limit of the surface temperature of the pressed portion at the time of heating is preferably the melting point of the binder to be used of minus 60 ° C. or higher, more preferably 45 ° C. or higher, still more preferably 30 ° C. or higher. On the other hand, the upper limit of the surface temperature of the pressed portion when heating is preferably the melting point of the binder used plus 50 ° C. or lower, more preferably 30 ° C. or lower, and further preferably 20 ° C. or lower. For example, when PVdF (polyvinylidene fluoride: melting point 150 ° C.) is used as the binder, it is preferable to heat it to 90 ° C. or higher and 200 ° C. or lower. It is more preferably 105 ° C. or higher and 180 ° C. or lower, and further preferably 120 ° C. or higher and 170 ° C. or lower. When a styrene-butadiene copolymer (melting point 100 ° C.) is used as the binder, it is preferable to heat the mixture to 40 ° C. or higher and 150 ° C. or lower. It is more preferably 55 ° C. or higher and 130 ° C. or lower, and further preferably 70 ° C. or higher and 120 ° C. or lower.

The melting point of the binder can be determined from the endothermic peak position of DSC (Differential Scanning Calorimetry, differential scanning calorimetry). For example, using a differential scanning calorimeter "DSC7" manufactured by PerkinElmer, 10 mg of sample resin is set in a measurement cell, and the temperature rises from 30 ° C. to 250 ° C. at a heating rate of 10 ° C./min in a nitrogen gas atmosphere. The temperature is raised, and the endothermic peak temperature in the temperature raising process becomes the melting point.
Further, the press may be performed a plurality of times while changing the conditions of the press pressure, the gap, the speed, and the surface temperature of the press portion.

The film thickness of the negative electrode active material layer is preferably 5 μm or more and 100 μm or less per side. The lower limit of the film thickness of the negative electrode active material layer is more preferably 7 μm or more, and more preferably 10 μm or more. The upper limit of the film thickness of the negative electrode active material layer is more preferably 80 μm or less, and more preferably 60 μm or less. When this film thickness is 5 μm or more, no streaks or the like are generated when the negative electrode active material layer is applied, and the coatability is excellent. On the other hand, when this film thickness is 100 μm or less, a high energy density can be developed by reducing the cell volume. The film thickness of the negative electrode active material layer when the current collector has through holes or irregularities means the average value of the film thickness per side of the portion of the current collector that does not have through holes or irregularities.

The bulk density of the negative electrode active material layer is preferably 0.30 g / cm ³ or more and 1.8 g / cm ³ or less, more preferably 0.40 g / cm ³ or more and 1.5 g / cm ³ or less, and further preferably 0. .45g / cm ³ or more 1.3g / cm ³ or less. When the bulk density is 0.30 g / cm ³ or more, sufficient strength can be maintained and sufficient conductivity between the negative electrode active materials can be exhibited. Further, if the amount is 1.8 g / cm ³ or less, pores capable of sufficiently diffusing ions can be secured in the negative electrode active material layer.

[Measurement item]
The BET specific surface area, average pore diameter, mesopore amount, and micropore amount in the present invention are values obtained by the following methods, respectively. The sample is vacuum-dried at 200 ° C. for 24 hours, and the isotherms of adsorption and desorption are measured using nitrogen as an adsorbent. Using the adsorption-side isotherm obtained here, the BET specific surface area is the BET multi-point method or the BET one-point method, and the average pore diameter is the mesopores by dividing the total pore volume per mass by the BET specific surface area. The amount is calculated by the BJH method, and the amount of micropores is calculated by the MP method.
The BJH method is a calculation method generally used for analysis of mesopores, and was proposed by Barrett, Joiner, Hallenda et al. (E.P. Barrett, L.G. Joiner and P. Hallenda, J. Am. Chem. Soc., 73, 373 (1951)).
Further, the MP method is a micropore volume, a micropore area, and a micropore area using the “t-plot method” (BC Lippens, JH de Boer, J. Catalysis, 4319 (1965)). It means a method for obtaining the distribution of micropores, and R. S. It is a method devised by Mikhair, Brunauer, and Bodor (RS Mikhair, S. Brunauer, EE Bodor, J. Colloid Interface Sci., 26, 45 (1968)).

The average particle size in the present invention is the particle size at the point where the cumulative curve is 50% when the cumulative curve is obtained with the total product as 100% when the particle size distribution is measured using the particle size distribution measuring device (that is,). Refers to 50% diameter (Median diameter). This average particle size can be measured using a commercially available laser diffraction type particle size distribution measuring device.

The amount of lithium ion doped in the negative electrode active material in the non-aqueous lithium-type power storage device at the time of shipment and after use in the present invention can be known, for example, as follows.
First, the negative electrode active material layer in the present embodiment is washed with ethyl methyl carbonate or dimethyl carbonate and air-dried, and then an extract extracted with a mixed solvent consisting of methanol and isopropanol and an extracted negative electrode active material layer are obtained. This extraction is typically performed in an Ar box at an environmental temperature of 23 ° C.
The amount of lithium contained in the extract obtained as described above and the negative electrode active material layer after extraction is quantified by using, for example, ICP-MS (inductively coupled plasma mass spectrometer) or the like. By obtaining the total, the amount of lithium ion doped in the negative electrode active material can be known. Then, the obtained value may be allocated by the amount of the negative electrode active material used for extraction to calculate the numerical value of the above unit.

For the primary particle size in the present invention, the powder is photographed in several fields with an electron microscope, and the particle size of the particles in those fields is measured by about 2,000 to 3,000 using a fully automatic image processing device or the like. However, it can be obtained by a method in which the value obtained by arithmetically averaging these is used as the primary particle size.

In the present specification, the dispersity is a value obtained by a dispersity evaluation test using a grain gauge specified in JIS K5600. That is, a sufficient amount of sample is poured into the tip of the deeper groove of the grain gauge having a groove of a desired depth according to the size of the grain, and the sample is slightly overflowed from the groove. Next, the long side of the scraper becomes parallel to the width direction of the gauge, and the cutting edge is placed so as to contact the deep tip of the groove of the grain gauge, and the scraper is held so as to be the surface of the gauge while the long side direction of the groove Pull the surface of the gauge at a right angle to the depth of the groove at a uniform speed for 1 to 2 seconds, and shine light at an angle of 20 ° to 30 ° within 3 seconds after the pulling is completed. Observe and read the depth at which the grains appear in the grooves of the grain gauge.

The viscosity (ηb) and TI value in the present invention are values obtained by the following methods, respectively. First, a stable viscosity (ηa) is obtained after measuring for 2 minutes or more under the conditions of a temperature of 25 ° C. and a shear rate of 2s- ¹ using an E-type viscometer. Next, the viscosity (ηb) measured under the same conditions as above is obtained except that the shear rate is changed to 20s ^-1 . Using the viscosity value obtained above, the TI value is calculated by the formula of TI value = ηa / ηb. When increasing the shear rate from 2s ^-1 to 20s ^-1 , the shear rate may be increased in one step, or the shear rate may be increased in multiple steps within the above range, and the viscosity at the shear rate may be appropriately obtained. You may let me.

[Compounds in the negative electrode active material layer]
The negative electrode active material layer according to the present invention contains one or more compounds selected from the formulas (1) to (3) at 0.50 × 10 ^-4 mol / g to 120 × per unit mass of the negative electrode material layer. It preferably contains 10 ^-4 mol / g.

As a method for incorporating the above-mentioned compound in the negative electrode active material layer in the present invention, for example,
A method of mixing the compound with the negative electrode active material layer,
A method of adsorbing the compound on the negative electrode active material layer,
Examples thereof include a method of electrochemically precipitating the compound on the negative electrode active material layer.
Above all, a negative electrode active material layer is contained in a non-aqueous electrolytic solution that can be decomposed to produce these compounds, and the decomposition reaction of the precursor in the step of producing a power storage element is utilized. A method of depositing the compound inside is preferable.

As the precursor for forming the compound, it is preferable to use at least one organic solvent selected from ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate and fluoroethylene carbonate, and ethylene carbonate and propylene carbonate are used. It is more preferable to do so.

Here, the total amount of the compound is preferably 0.50 × 10 ^-4 mol / g or more, and more than 1.0 × 10 ^-4 mol / g, per unit mass of the negative electrode active material layer. Is more preferable. When the total amount of the compound is 0.50 × 10 ^-4 mol / g or more per unit mass of the negative electrode active material layer, the non-aqueous electrolyte solution does not come into contact with the negative electrode active material, and the non-aqueous electrolyte solution is reduced and decomposed. It is possible to suppress the generation of gas.
The total amount of the compound is preferably 120 × 10 ^-4 mol / g or less, more preferably 100 × 10 ^-4 mol / g or less, and more preferably 80 per unit mass of the negative electrode active material layer. Most preferably, it is × 10 ^-4 mol / g or less. When the total amount of the compound is 120 × 10 ^-4 mol / g or less per unit mass of the negative electrode active material layer, high input / output characteristics can be exhibited without inhibiting the diffusion of Li ions at the negative electrode interface. it can.

The ratio A / B of the content A per unit mass of the positive electrode material layer to the content B per unit mass of the negative electrode material layer of the compound according to the present invention is 0.2 or more and 20 or less. The A / B is more preferably 0.8 or more and 15 or less, and further preferably 1.2 or more and 12 or less. When the A / B is 0.2 or more, the non-aqueous electrolytic solution is not oxidatively decomposed at the positive electrode interface to generate gas, and the diffusion of Li ions is not hindered at the negative electrode interface. Further, when the A / B is 20 or less, the non-aqueous electrolytic solution is not reduced and decomposed at the negative electrode interface to generate gas, and the diffusion of Li ions is not hindered at the positive electrode interface. Therefore, when the A / B is 0.2 or more and 20 or less, it is possible to achieve both sufficient high temperature durability and high input / output characteristics in a wide range of temperatures.

[Electrolytic solution]
The electrolytic solution of this embodiment is a non-aqueous electrolytic solution. That is, this electrolytic solution contains a non-aqueous solvent described later. The non-aqueous electrolyte solution preferably contains 0.5 mol / L or more of lithium salt based on the total amount of the non-aqueous electrolyte solution. That is, the non-aqueous electrolyte solution contains lithium ions as an electrolyte.

[Lithium salt]
The non-aqueous electrolyte solution of the present embodiment has, as lithium salts, for example, (LiN (SO ₂ F) ₂ ), LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiN (SO _2). CF ₃ ) (SO ₂ C ₂ F ₅ ), LiN (SO ₂ CF ₃ ) (SO ₂ C ₂ F ₄ H), LiC (SO ₂ F) ₃ , LiC (SO ₂ CF ₃ ) ₃ , LiC (SO ₂₎ C ₂ F ₅ ) ₃ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiPF ₆ , LiBF _4, etc. can be used alone, or two or more of them may be mixed and used. It is preferable to contain LiPF ₆ and / or LiN (SO ₂ F) ₂ because it can exhibit high conductivity.
The lithium salt concentration in the non-aqueous electrolyte solution is preferably 0.5 mol / L or more, more preferably 0.5 mol / L or more and 2.0 mol / L or less, based on the total amount of the non-aqueous electrolyte solution. .. When the lithium salt concentration is 0.5 mol / L or more, anions are sufficiently present, so that the capacity of the power storage element can be sufficiently increased. Further, when the lithium salt concentration is 2.0 mol / L or less, it is possible to prevent undissolved lithium salt from precipitating in the non-aqueous electrolyte solution and the viscosity of the electrolyte solution from becoming too high, resulting in a decrease in conductivity. It is preferable because it does not reduce the output characteristics.

The non-aqueous electrolyte solution of the present embodiment preferably contains LiN (SO ₂ F) ₂ having a concentration of 0.1 mol / L or more and 1.5 mol / L or less based on the total amount of the non-aqueous electrolyte solution, more preferably. Is 0.3 mol / L or more and 1.2 mol / L or less. When LiN (SO ₂ F) ₂ is 0.1 mol / L or more, the ionic conductivity of the electrolytic solution is increased, and an appropriate amount of an electrolyte film is deposited on the negative electrode interface, thereby reducing gas due to decomposition of the electrolytic solution. can do. On the other hand, when this value is 1.5 mol / L or less, precipitation of the electrolyte salt does not occur during charging / discharging, and the viscosity of the electrolytic solution does not increase even after a long period of time.

[Non-aqueous solvent]
The non-aqueous electrolyte solution of the present embodiment contains a cyclic carbonate as a non-aqueous solvent. The inclusion of the cyclic carbonate in the non-aqueous electrolyte solution is advantageous in that it dissolves a lithium salt having a desired concentration and that an appropriate amount of the lithium compound is deposited on the positive electrode active material layer. Examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate and the like.
The total content of the cyclic carbonate is preferably 15% by mass or more, more preferably 20% by mass or more, based on the total amount of the non-aqueous electrolyte solution. When the total content is 15% by mass or more, a lithium salt having a desired concentration can be dissolved, and high lithium ion conductivity can be exhibited. Further, an appropriate amount of lithium compound can be deposited on the positive electrode active material layer, and oxidative decomposition of the electrolytic solution can be suppressed.

The non-aqueous electrolyte solution of the present embodiment preferably contains a chain carbonate as a non-aqueous solvent. It is advantageous that the non-aqueous electrolyte solution contains a chain carbonate in that it exhibits high lithium ion conductivity. Examples of the chain carbonate include dialkyl carbonate compounds typified by dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, dibutyl carbonate and the like. Dialkyl carbonate compounds are typically unsubstituted.
The total content of the chain carbonate is preferably 30% by mass or more, more preferably 35% by mass or more, preferably 95% by mass or less, and more preferably 90% by mass or less, based on the total amount of the non-aqueous electrolyte solution. is there. When the content of the chain carbonate is 30% by mass or more, the viscosity of the electrolytic solution can be reduced and high lithium ion conductivity can be exhibited. When the total concentration is 95% by mass or less, the electrolytic solution can further contain the additives described later.

[Additive]
The non-aqueous electrolyte solution of the present embodiment may further contain an additive. The additive is not particularly limited, and for example, a sultone compound, cyclic phosphazene, acyclic fluorinated ether, fluorinated cyclic carbonate, cyclic carbonate, cyclic carboxylic acid ester, cyclic acid anhydride and the like may be used alone. It is possible, and two or more kinds may be mixed and used.

｛式（５）中、Ｒ^１１〜Ｒ^１６は、水素原子、ハロゲン原子、炭素数１〜１２のアルキル基、又は炭素数１〜１２のハロゲン化アルキル基を表し、互いに同一であっても異なっていてもよく；そしてｎは０〜３の整数である。｝

｛式（６）中、Ｒ^１１〜Ｒ^１４は、水素原子、ハロゲン原子、炭素数１〜１２のアルキル基、又は炭素数１〜１２のハロゲン化アルキル基を表し、互いに同一であっても異なっていてもよく；そしてｎは０〜３の整数である。｝

｛式（７）中、Ｒ^１１〜Ｒ^１６は、水素原子、ハロゲン原子、炭素数１〜１２のアルキル基、又は炭素数１〜１２のハロゲン化アルキル基を表し、互いに同一であっても異なっていてもよい。｝ [Sultone compound]
Examples of the sultone compound include sultone compounds represented by the following general formulas (5) to (7). These sultone compounds may be used alone or in combination of two or more.

{In formula (5), R ^{11 to} R ¹⁶ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkyl halide group having 1 to 12 carbon atoms, and they are different even if they are the same. May be; and n is an integer from 0 to 3. }

{In formula (6), R ^{11 to} R ¹⁴ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkyl halide group having 1 to 12 carbon atoms, and they are different even if they are the same. May be; and n is an integer from 0 to 3. }

{In formula (7), R ^{11 to} R ¹⁶ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkyl halide group having 1 to 12 carbon atoms, and they are different even if they are the same. May be. }

In the present embodiment, the sultone compound represented by the general formula (5) is selected from the viewpoint of having little adverse effect on resistance and suppressing decomposition of the non-aqueous electrolyte solution at high temperature to suppress gas generation. 1,3-Propane sultone, 2,4-butane sultone, 1,4-butane sultone, 1,3-butane sultone or 2,4-pentane sultone are preferable, and the sultone compound represented by the general formula (6) is 1, 3-Propens sultone or 1,4-butene sultone is preferable, and the sultone compound represented by the general formula (7) is 1,5,2,4-dioxadithioepan 2,2,4,4-tetraoxide. As the other sultone compounds, methylenebis (benzenesulfonic acid), methylenebis (phenylmethanesulfonic acid), methylenebis (ethanesulfonic acid), methylenebis (2,4,6,trimethylbenzenesulfonic acid), and methylenebis (2). -Trifluoromethylbenzene sulfonic acid), and it is preferable to select at least one selected from these.

The total content of the sultone compound in the non-aqueous electrolyte solution of the non-aqueous lithium-type power storage element in the present embodiment is preferably 0.5% by mass or more and 15% by mass or less based on the total amount of the non-aqueous electrolyte solution. .. When the total content of the sultone compound in the non-aqueous electrolytic solution is 0.5% by mass or more, it is possible to suppress the decomposition of the electrolytic solution at a high temperature and suppress the gas generation. On the other hand, when the total content is 15% by mass or less, the decrease in ionic conductivity of the electrolytic solution can be suppressed, and high input / output characteristics can be maintained. Further, the content of the sultone compound present in the non-aqueous electrolyte solution of the non-aqueous lithium-type power storage element is preferably 1% by mass or more and 10% by mass or less from the viewpoint of achieving both high input / output characteristics and durability. It is preferably 3% by mass or more and 8% by mass or less.

[Circular phosphazene]
Examples of the cyclic phosphazene include ethoxypentafluorocyclotriphosphazene, diethoxytetrafluorocyclotriphosphazene, and phenoxypentafluorocyclotriphosphazene, and one or more selected from these is preferable.

The content of cyclic phosphazene in the non-aqueous electrolyte solution is preferably 0.5% by mass or more and 20% by mass or less based on the total amount of the non-aqueous electrolyte solution. When this value is 0.5% by weight or more, it is possible to suppress the decomposition of the electrolytic solution at a high temperature and suppress the gas generation. On the other hand, when this value is 20% by mass or less, it is possible to suppress a decrease in the ionic conductivity of the electrolytic solution and maintain high input / output characteristics. The content of cyclic phosphazene is more preferably 2% by mass or more and 15% by mass or less, and further preferably 4% by mass or more and 12% by mass or less. These cyclic phosphazenes may be used alone or in combination of two or more.

[Acyclic fluorine-containing ether]
Examples of the acyclic fluorine-containing ether include HCF ₂ CF ₂ OCH ₂ CF ₂ CF ₂ H, CF ₃ CFHCF ₂ OCH ₂ CF ₂ CF ₂ H, HCF ₂ CF ₂ CH ₂ OCH ₂ CF ₂ CF ₂ H, CF ₃ CFHCF ₂ OCH ₂ CF ₂ CFHCF _{3 and the} like can be mentioned, and among them, HCF ₂ CF ₂ OCH ₂ CF ₂ CF ₂ H is preferable from the viewpoint of electrochemical stability.

The content of the acyclic fluorinated ether is preferably 0.5% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 10% by mass or less, based on the total amount of the non-aqueous electrolyte solution. When the content of the acyclic fluorinated ether is 0.5% by mass or more, the stability of the non-aqueous electrolyte solution against oxidative decomposition is enhanced, and a power storage element having high durability at high temperatures can be obtained. On the other hand, when the content of the acyclic fluorinated ether is 15% by mass or less, the solubility of the electrolyte salt can be kept good and the ionic conductivity of the non-aqueous electrolyte solution can be kept high, so that the concentration is high. It is possible to express input / output characteristics. The acyclic fluorine-containing ether may be used alone or in combination of two or more.

[Fluorine-containing cyclic carbonate]
The fluorine-containing cyclic carbonate is preferably used by selecting from fluoroethylene carbonate (FEC) and difluoroethylene carbonate (dFEC) from the viewpoint of compatibility with other non-aqueous solvents.
The content of the cyclic carbonate containing a fluorine atom is preferably 0.5% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 5% by mass or less, based on the total amount of the non-aqueous electrolyte solution. When the content of the cyclic carbonate containing a fluorine atom is 0.5% by mass or more, a high-quality film can be formed on the negative electrode, and by suppressing the reductive decomposition of the electrolytic solution on the negative electrode, the temperature is high. A power storage element with high durability can be obtained. On the other hand, when the content of the cyclic carbonate containing a fluorine atom is 10% by mass or less, the solubility of the electrolyte salt can be kept good and the ionic conductivity of the non-aqueous electrolyte solution can be kept high. It is possible to express a high degree of input / output characteristics. The above-mentioned cyclic carbonate containing a fluorine atom may be used alone or in combination of two or more.

[Cyclic carbonate]
As for the cyclic carbonate, vinylene carbonate is preferable.
The content of the cyclic carbonate is preferably 0.5% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 5% by mass or less, based on the total amount of the non-aqueous electrolyte solution. When the content of the cyclic carbonate is 0.5% by mass or more, a high-quality film can be formed on the negative electrode, and by suppressing the reductive decomposition of the electrolytic solution on the negative electrode, the durability at high temperature can be improved. A high power storage element can be obtained. On the other hand, when the content of the cyclic carbonate is 10% by mass or less, the solubility of the electrolyte salt can be kept good and the ionic conductivity of the non-aqueous electrolyte solution can be maintained high, so that the input / output is highly high. It becomes possible to express the property.

[Cyclic carboxylic acid ester]
Examples of the cyclic carboxylic acid ester include gamma-butyrolactone, gamma valerolactone, gamma caprolactone, and epsilon caprolactone, and it is preferable to use one or more selected from these. Of these, gamma-butyrolactone is particularly preferable from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation.
The content of the cyclic carboxylic acid ester is preferably 0.5% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 5% by mass or less, based on the total amount of the non-aqueous electrolyte solution. When the content of cyclic acid anhydride is 0.5% by mass or more, a high-quality film can be formed on the negative electrode, and by suppressing the reductive decomposition of the electrolytic solution on the negative electrode, durability at high temperature is achieved. A high power storage element can be obtained. On the other hand, when the content of the cyclic carboxylic acid ester is 5% by mass or less, the solubility of the electrolyte salt can be kept good and the ionic conductivity of the non-aqueous electrolyte solution can be maintained high, so that the content is high. It is possible to express output characteristics. The above cyclic carboxylic acid ester may be used alone or in combination of two or more.

[Cyclic acid anhydride]
As the cyclic acid anhydride, one or more selected from succinic anhydride, maleic anhydride, citraconic anhydride, and itaconic anhydride are preferable. Among them, it is preferable to select from succinic anhydride and maleic anhydride from the viewpoint that the production cost of the electrolytic solution can be suppressed due to the industrial availability and the dissolution in the non-aqueous electrolytic solution is easy.
The content of the cyclic acid anhydride is preferably 0.5% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 10% by mass or less, based on the total amount of the non-aqueous electrolyte solution. When the content of cyclic acid anhydride is 0.5% by mass or more, a high-quality film can be formed on the negative electrode, and by suppressing the reductive decomposition of the electrolytic solution on the negative electrode, the durability at high temperature can be improved. A high power storage element can be obtained. On the other hand, when the content of the cyclic acid anhydride is 10% by mass or less, the solubility of the electrolyte salt can be kept good, and the ionic conductivity of the non-aqueous electrolyte solution can be maintained high, and therefore a high degree of input / output can be maintained. It becomes possible to express the property. The above cyclic acid anhydride may be used alone or in combination of two or more.

[Separator]
The positive electrode precursor and the negative electrode are wound via a separator to form an electrode wound body having the positive electrode precursor, the negative electrode and the separator.
As the separator, a polyethylene microporous film or polypropylene microporous film used in a lithium ion secondary battery, a cellulose non-woven paper used in an electric double layer capacitor, or the like can be used. A film made of organic or inorganic fine particles may be laminated on one side or both sides of these separators. Further, organic or inorganic fine particles may be contained inside the separator.
The thickness of the separator is preferably 5 μm or more and 35 μm or less. A thickness of 5 μm or more is preferable because self-discharge due to internal microshorts tends to be small. On the other hand, a thickness of 35 μm or less is preferable because the input / output characteristics of the non-aqueous lithium power storage element tend to be improved.
The film made of organic or inorganic fine particles is preferably 1 μm or more and 10 μm or less. A thickness of 1 μm or more is preferable because self-discharge due to internal microshorts tends to be small. On the other hand, a thickness of 10 μm or less is preferable because the input / output characteristics of the non-aqueous lithium power storage element tend to be improved.
[Non-aqueous lithium-type power storage element]
The non-aqueous lithium-type power storage element of the present embodiment is configured such that an electrode winding body, which will be described later, is housed in the exterior body together with the non-aqueous electrolytic solution.

[assembly]
The electrode winding body obtained in the process of assembling the power storage element is formed by connecting a positive electrode terminal and a negative electrode terminal to a winding body formed by winding a positive electrode precursor and a negative electrode via a separator. The shape of the electrode winding body may be cylindrical or flat. An example of a flat type wound body is shown in FIG.
The method of connecting the positive electrode terminal and the negative electrode terminal is not particularly limited, but a method such as resistance welding or ultrasonic welding is used.

[Opposite and non-opposing parts]
The power storage element having a structure in which the positive electrode active material layer of the positive electrode precursor and the negative electrode active material layer of the negative electrode face each other via a separator is designed so that the area of the negative electrode is slightly larger than the area of the positive electrode. This is to reduce the variation in the facing areas of the positive and negative electrodes and to prevent lithium from precipitating in a portion other than the negative electrode active material layer. Therefore, in the negative electrode active material layer, an opposing portion facing the positive electrode active material layer and a non-opposing portion not facing the positive electrode active material layer coexist via the separator. In particular, in the winding type power storage element, there are remarkable non-opposing portions at the winding start portion and the winding end portion in the circumferential direction rather than the non-opposing portion in the winding axis direction.
When lithium ions move to a non-opposing portion of the negative electrode and are occluded, the occluded lithium ions are unlikely to contribute to the charge / discharge reaction, and there is a concern that the capacity of the power storage element may decrease. Therefore, it is preferable to mask the non-opposing portion to reduce the amount of lithium ions doped into the non-opposing portion in the lithium doping step described later. By reducing the doping amount of the non-opposing portion, the negative electrode potential of the non-opposing portion becomes relatively higher than the negative electrode potential of the facing portion. Therefore, it is difficult for lithium ions to move to the non-opposing portion, and it is possible to suppress a decrease in capacity.
The masking is preferably made of an ion-impermeable member made of a material that does not allow lithium ions to permeate, such as a polyolefin-based resin such as polyethylene or polypropylene. It is advisable to attach a handle to the masking so that it can be removed in the degassing step described later. Since it does not remain in the completed power storage element, there is no concern that the volume and weight will increase.
Further, in order to make a difference in the negative electrode potential between the facing portion and the non-opposing portion, it is possible to control the current value in the lithium doping step in addition to the above masking.

[Exterior body]
As the exterior body, a metal can, a laminated packaging material, or the like can be used. The metal can is preferably made of aluminum. As the laminated packaging material, a film obtained by laminating a metal foil and a resin film is preferable, and a three-layer structure composed of an outer layer resin film / metal foil / interior resin film is exemplified. The outer layer resin film is for preventing the metal foil from being damaged by contact or the like, and a resin such as nylon or polyester can be preferably used. The metal foil is for preventing the permeation of moisture and gas, and a foil such as copper, aluminum, or stainless steel can be preferably used. Further, the interior resin film is for protecting the metal foil from the non-aqueous electrolyte solution stored inside and for melting and sealing the exterior body at the time of heat sealing, and polyolefins, acid-modified polyolefins and the like can be preferably used.

[Storage in the exterior]
It is preferable that the dried electrode wound body is housed in an outer body typified by a metal can or a laminated packaging material, and sealed with only one opening left. The sealing method of the outer body is not particularly limited, but when a laminated packaging material is used, a method such as heat sealing or impulse sealing is used.

[Dry]
It is preferable that the electrode wound body housed in the outer body is dried to remove the residual solvent. The drying method is not limited, but it is dried by vacuum drying or the like. The residual solvent is preferably 1.5% by mass or less per mass of the positive electrode active material layer or the negative electrode active material layer. If the residual solvent is more than 1.5% by mass, the solvent remains in the system and the self-discharge characteristics and cycle characteristics are deteriorated, which is not preferable.

[Liquid injection, impregnation, sealing process]
After the assembly process is completed, the non-aqueous electrolyte solution is injected into the electrode winding body housed in the exterior body. After the completion of the liquid injection step, it is desirable to further impregnate and sufficiently immerse the positive electrode, the negative electrode, and the separator with a non-aqueous electrolytic solution. When the non-aqueous electrolyte solution is not immersed in at least a part of the positive electrode, the negative electrode, and the separator, the doping proceeds non-uniformly in the lithium doping step described later, so that the resistance of the obtained non-aqueous lithium storage element becomes high. It rises or becomes less durable. The impregnation method is not particularly limited, but for example, the electrode winding body after injection is installed in a decompression chamber with the outer body open, and the inside of the chamber is decompressed using a vacuum pump. A method of returning to atmospheric pressure or the like can be used. After the impregnation step is completed, the electrode wound body with the outer body open is sealed while reducing the pressure.

[Lithium doping process]
In the lithium doping step, a preferable step is to apply a voltage between the positive electrode precursor and the negative electrode to decompose the lithium compound, thereby decomposing the lithium compound in the positive electrode precursor and releasing lithium ions. By reducing lithium ions at the negative electrode, liotium ions are pre-doped into the active material layer facing the negative electrode. On the other hand, in the non-opposing portion of the negative electrode, since there is no facing positive electrode, reduction of lithium ions is unlikely to occur, and the lithium ion concentration is relatively low. The lithium ion concentration in the non-opposing portion tends to decrease as the distance from the positive electrode increases, and has a concentration gradient. In order to make this relative lithium ion concentration difference more remarkable, a method of masking the non-opposing portion of the negative electrode and a method of controlling the doping current value can be mentioned. When the non-opposing portion of the negative electrode is masked, lithium ions do not permeate and predoping to the non-opposing portion is suppressed. At this time, the non-opposing portion is slightly reduced by the lithium ions diffused from the active material layer on the facing portion of the negative electrode and the electrolytic solution containing lithium ions permeating through the gap between the masking and the active material layer on the non-opposing portion. Doped.
As described above, in order to make a difference between the negative electrode potentials of the facing portion and the non-opposing portion, a method of masking the non-opposing portion of the negative electrode to physically suppress doping or controlling the doping current value by a potential gradient is used. There is a way to make spots. A good potential difference can be created by using both of these methods in combination or by using only the control of the doping current value.
In the masking method, a gap through which the electrolytic solution permeates may or may not be provided between the masking and the negative electrode. In the method of controlling the doping current value, when the current value is increased, the potential difference between the facing portion and the non-opposing portion tends to increase, and the potential gradient in the non-opposing portion also becomes steep.
The potential difference between the non-opposing portion and the non-opposing portion is preferably +50 mV or more from the viewpoint that lithium ions are difficult to move to the non-opposing portion. More preferably, it is +80 mV or more. The potential gradient is preferably 500 mV / m or more in order to prevent the lithium ions that have entered the non-opposing portion from moving to the end portion during charging / discharging. More preferably, it is 650 mV / m or more.
Further, in this lithium doping step, gas such as CO ₂ is generated due to oxidative decomposition of the lithium compound in the positive electrode precursor. Therefore, when applying a voltage, it is preferable to take measures to release the generated gas to the outside of the exterior body. As this means, for example, a method of applying a voltage with a part of the exterior body opened; a state in which an appropriate gas release means such as a gas vent valve or a gas permeable film is previously installed in the part of the exterior body. A method of applying a voltage with the above;

[Aging process]
It is preferable to age the electrode wound body after the lithium doping step is completed. In the aging step, the solvent in the non-aqueous electrolyte solution is decomposed at the negative electrode, and a lithium ion permeable solid polymer film is formed on the surface of the negative electrode.
The aging method is not particularly limited, and for example, a method of reacting a solvent in a non-aqueous electrolyte solution in a high temperature environment can be used.

[Degassing process]
After the aging step is completed, it is preferable to further degas to surely remove the gas remaining in the non-aqueous electrolyte solution, the positive electrode, and the negative electrode. In a state where gas remains in at least a part of the non-aqueous electrolyte solution, the positive electrode, and the negative electrode, ion conduction is inhibited, so that the resistance of the obtained non-aqueous lithium power storage element increases.
The method for degassing is not particularly limited, but for example, a method is used in which the electrode winding body is installed in a decompression chamber with the exterior body opened and the inside of the chamber is decompressed using a vacuum pump. be able to. Further, when the non-opposing portion of the negative electrode is masked, it is preferable to remove the masking when the exterior body is opened in the degassing step.

[Completed non-aqueous lithium-type power storage element]
[Negative potential in facing and non-facing parts]
The potential difference of the non-opposing portion with respect to the facing portion is preferably as high as 50 mV or more from the viewpoint that lithium ions are difficult to move to the non-opposed portion. More preferably, the negative electrode potential of the non-opposing portion is 80 mV or more higher than that of the facing portion. If the negative electrode potential of the non-opposing portion is 50 mV or more higher than the negative electrode potential of the facing portion, the lithium ions during charging / discharging are difficult to move to the non-opposing portion, and the lithium ions are concentrated on the facing portion, which contributes to the charge / discharge reaction. It is possible to provide a power storage element having an increased capacity and a high energy density. Further, since lithium ions are difficult to move to the non-opposing portion, extra diffusion resistance can be reduced and high input / output characteristics can be obtained.
The negative electrode potential of the facing portion is preferably 50 mV or more and 300 mV or less, more preferably 60 mV or more and 250 mV or less, based on metallic lithium. If it is 50 mV or more, precipitation of lithium can be prevented, and if it is 300 mV or less, lithium ions are easily diffused and high input / output characteristics can be obtained.
The potential gradient is preferably 500 mV / m or more in order to prevent the lithium ions that have entered the non-opposing portion from moving to the end portion during charging / discharging. More preferably, it is 650 mV / m or more. If the potential gradient is 500 mV / m or more, even if lithium ions move into the active material in the non-opposing portion during the charge / discharge cycle, it can be prevented from further diffusing / moving. That is, it is possible to provide a power storage element having cycle durability with less decrease in capacity even in a long-term charge / discharge cycle.
The potential difference and the potential gradient described above may be present at least one or more in the power storage element.

[Lithium ion concentration in facing and non-opposing parts]
The ratio of the lithium ion concentration (mass%) of the non-opposing portion to the facing portion is preferably 0.85 or less from the viewpoint of expressing the negative electrode potential described above. More preferably, it is 0.75 or less. When the lithium ion concentration (mass%) of the non-opposing portion with respect to the facing portion is 0.85 or less, it is easy to develop a good negative electrode potential difference, it is difficult for lithium ions to move to the non-opposing portion, and lithium ions are generated in the facing portion. Since it concentrates and contributes to the charge / discharge reaction, it is possible to provide a power storage element having an increased capacity and a high energy density. Further, since lithium ions are difficult to move to the non-opposing portion, extra diffusion resistance can be reduced and high input / output characteristics can be obtained.

[Thickness of negative electrode in facing and non-facing]
The ratio of the thickness of the negative electrode of the non-opposing portion to the thickness of the negative electrode of the facing portion is preferably 0.80 or more and 0.95 or less. This is because the negative electrode active material in the facing portion expands because lithium ions are inserted, whereas the negative electrode active material in the non-opposing portion has a larger amount of lithium ions occluded than the occluded amount in the facing portion. This is because it is small and the degree of expansion is small. If the ratio of the thickness of the negative electrode of the non-opposing portion to the facing portion is 0.80 or more, the stress generated at the boundary between the facing portion and the non-opposing portion during expansion and contraction of the negative electrode can be relaxed, and the charge / discharge cycle or the like can be relaxed. Durability is improved. Further, if the ratio of the thickness of the negative electrode of the non-opposing portion to the facing portion is 0.95 or less, it is possible to contribute to the miniaturization of the power storage element, which leads to the improvement of the energy density per volume.

[Characteristic evaluation of non-aqueous lithium-type power storage element]
[Capacitance]
In the present specification, the capacitance F (F) is a value obtained by the following method:
First, in a constant temperature bath in which the cell corresponding to the non-aqueous lithium-type power storage element is set to 25 ° C, constant current charging is performed until the current value of 20C reaches 3.8V, and then a constant voltage of 3.8V is applied. The constant voltage charging to be applied is performed for a total of 30 minutes. After that, let Q be the capacitance when constant current discharge is performed with a current value of 2C up to 2.2V. It means a value calculated by F = Q / (3.8-2.2) using the Q obtained here.

[Electric energy]
In the present specification, the electric energy E (Wh) is a value obtained by the following method:
It refers to a value calculated by F × (3.8 ² -2.2 ² ) / 2/3600 using the capacitance F (F) calculated by the method described above.

[volume]
The volume of the non-aqueous lithium power storage element is not particularly specified, but the volume of the portion of the electrode winding body in which the positive electrode active material layer and the negative electrode active material layer are stacked is the volume of the portion housed by the exterior body. Point to.
For example, in the case of an electrode wound body housed by a laminate film, a region of the electrode wound body in which the positive electrode active material layer and the negative electrode active material layer exist is stored in the cup-formed laminate film. However, the volume (V ₁ ) of this non-aqueous lithium-type storage element is the outer dimension length (l ₁ ), outer dimension width (w ₁ ), and non-aqueous lithium storage element of the cup-molded portion. It is calculated by V ₁ = l ₁ × w ₁ × t _{1 according} to the thickness of the element (t ₁ ).
In the case of an electrode winding body housed in a square metal can, the volume of the non-aqueous lithium power storage element is simply the volume of the outer dimension of the metal can. That is, the volume (V ₂ ) of this non-aqueous lithium-type power storage element is V depending on the outer dimension length (l ₂ ), outer dimension width (w ₂ ), and outer dimension thickness (t ₂ ) of the square metal can. It is calculated by ₂ = l ₂ × w ₂ × t ₂ .
Further, even in the case of the electrode wound body housed in the cylindrical metal can, the volume of the non-aqueous lithium power storage element is the volume of the outer dimension of the metal can. That is, the volume (V ₃ ) of this non-aqueous lithium type power storage element is V ₃ = 3.14 depending on the outer dimension radius (r) and the outer dimension length (l ₃ ) of the bottom surface or the upper surface of the cylindrical metal can. It is calculated by × r × r × l ₃ .
[Energy density]
In the present specification, the energy density is a value obtained by the equation of _{E / V i (Wh / L} ) using the amount of electricity E and the volume _V i (i = 1,2,3).

[Room temperature discharge internal resistance]
In the present specification, the room temperature discharge internal resistance Ra (Ω) is a value obtained by the following method:
First, the cell corresponding to the non-aqueous lithium-type power storage element is charged with a constant current at a current value of 20 C until it reaches 3.8 V in a constant temperature bath set at 25 ° C., and then a constant voltage of 3.8 V is applied. The constant voltage charging is performed for a total of 30 minutes. Subsequently, a constant current discharge is performed up to 2.2 V with a current value of 20 C to obtain a discharge curve (time-voltage). In this discharge curve, when the voltage at the discharge time = 0 second obtained by extrapolating from the voltage values at the discharge times of 2 seconds and 4 seconds is set to Eo, the voltage drop ΔE = 3.8- It is a value calculated by Eo and Ra = ΔE / (20C (current value A)).

[Rate of increase in internal resistance of normal temperature discharge after high load charge / discharge cycle test]
In the present specification, the rate of increase in internal resistance of normal temperature discharge after a high load charge / discharge cycle test is measured by the following method:
First, the cell corresponding to the non-aqueous lithium-type power storage element is charged at a constant current in a constant temperature bath set at 25 ° C. until it reaches 3.8 V at a current value of 300 C, and then 2.2 V at a current value of 300 C. Constant current discharge is performed until reaches. The charge / discharge process is repeated 60,000 times, and the internal resistance of normal temperature discharge is measured before the start of the test and after the end of the test. When Ω) is set, the resistance increase rate after the high load charge / discharge cycle test before the start of the test is calculated by Re / Ra.

[Capacity recovery rate after high load charge / discharge cycle test]
In the present specification, the capacity recovery rate after the high load charge / discharge cycle test is measured by the following method:
First, the cell corresponding to the non-aqueous lithium-type power storage element is charged at a constant current in a constant temperature bath set at 25 ° C. until it reaches 3.8 V at a current value of 300 C, and then 2.2 V at a current value of 300 C. Constant current discharge is performed until reaches. The charge / discharge process is repeated 60,000 times, and after the voltage reaches 4.5 V at a current value of 20 C, the battery is charged at a constant voltage for 1 hour. After that, when the capacitance value obtained by using the same measurement method as the capacitance is the capacitance Fe after the high load charge / discharge cycle test, the capacitance value is the capacitance before the start of the high load charge / discharge cycle test. The capacitance recovery rate after the high load charge / discharge cycle test for F is calculated by Fe / F.

[Measurement of negative electrode potential in opposite and non-opposing parts]
When the completed retractable non-aqueous lithium power storage element is disassembled so that the positive electrode and the negative electrode do not come into contact with each other, the schematic diagram shown in FIG. 2 is obtained. As shown in FIG. 2, the negative electrode active material obtained after dismantling has an opposing portion facing the positive electrode active material and a non-opposing portion not facing the positive electrode active material, and both sides of the negative electrode are facing portions. There are a portion, a portion where one side is a facing portion, and a portion where both sides are non-opposing portions. The potential measurement of the non-opposing portion in the present specification is performed for a portion where both sides are non-opposing portions. On the other hand, the potential measurement of the facing portion is performed on a portion where both sides of the negative electrode are facing portions. The method of measuring the negative electrode potential in the facing portion and the non-opposing portion is as follows. The measurement was carried out in an argon atmosphere in order to handle an electrode that occludes lithium.
1. 1. Opposing portion A portion where both sides of the negative electrode are opposed to each other is cut out, and metallic lithium wrapped in a separator which is a reference electrode is pressed against the electrode liquid to drop an electrolytic solution. Then, in a well-impregnated state, the potential difference between the reference electrode and the uncoated portion (copper foil) of the negative electrode is measured at five points with a tester, and the average value is taken as the negative electrode potential of the opposite portion.
2. 2. Non-opposing portion A portion where both sides of the negative electrode are non-opposing portions is cut out, and metallic lithium wrapped in a separator, which is a reference electrode, is pressed against the portion to drop an electrolytic solution. Then, in a well-impregnated state, the potential difference between the reference electrode and the uncoated portion (copper foil) of the negative electrode is measured at five points with a tester, and the averaged value is taken as the negative electrode potential of the non-opposing portion.
As described above, the negative electrode potentials of the facing portion and the non-opposing portion are measured. The potential difference between the facing portion and the non-opposing portion defined in the present specification is calculated by (negative electrode potential of the non-opposing portion)-(negative electrode potential of the facing portion).

[Measurement of negative electrode potential gradient in non-opposing part]
A portion where both sides of the negative electrode are non-opposing portions is cut out and divided into five as shown in FIG. Next, the negative electrode potentials at five locations are measured in the same manner as in the above-described [method for measuring the negative electrode potentials in the facing portion and the non-opposing portion], and the maximum value Vmax and the minimum value Vmin of the negative electrode potentials are obtained. The distance L between the non-opposing portion piece of the negative electrode having the maximum value and the non-opposing portion piece having the minimum value is measured, and the potential gradient is calculated by (Vmax-Vmin) / L.

[Measurement of lithium amount]
As a solid ⁷ Li-NMR measuring device, a commercially available device can be used. In a room temperature environment, the rotation speed of the magic angle spinning is 14.5 kHz, the irradiation pulse width is 45 ° pulse, and the measurement is performed by the single pulse method. When measuring, set so that there is a sufficient waiting time for repetition between measurements. A 1 mol / L lithium chloride aqueous solution is used as a shift reference, and the shift position measured separately as an external standard is 0 ppm. When measuring a 1 mol / L lithium chloride aqueous solution, the sample is not rotated, and the irradiation pulse width is set to 45 ° pulse, and the measurement is performed by the single pulse method.
With respect to the solid ⁷ Li-NMR spectrum of the negative electrode active material layer obtained by the above method, the peak area is determined for the components in the range of 4 ppm to 30 ppm. Then, these peak areas are divided by the peak area of a 1 mol / L lithium chloride aqueous solution measured by setting the sample height in the measuring rotor to be the same as that at the time of measuring the negative electrode active material layer, and further, the negative electrode active material used for the measurement. The amount of lithium in the negative electrode active material layer can be calculated by dividing by the mass of the layer. The mass of the negative electrode active material layer is the mass of the negative electrode active material layer containing lithium ions occluded in the negative electrode active material layer, a coating film and deposits contained in the negative electrode active material layer, and the like. Further, the amount of lithium in the negative electrode active material layer is synonymous with the amount of lithium ions, and the amount of lithium per unit mass of the negative electrode active material in the non-opposing portion is divided by the amount of lithium per unit mass of the negative electrode active material in the facing portion. Therefore, the lithium ion concentration ratio of the non-opposing portion to the facing portion can be calculated.

[Measurement of negative electrode film thickness ratio of non-opposing part to facing part]
The measurement is carried out in an argon atmosphere. In the negative electrode taken out by disassembling the power storage element, the film thickness of the facing portion and the film thickness of the non-opposing portion on both sides are measured with a film thickness meter at five locations and averaged. The film thickness T2 of the non-opposing portion with T1 is obtained. The film thickness ratio is calculated by obtaining the ratio of the film thickness T2 of the non-opposing portion to the film thickness T1 of the facing portion, T2 / T1.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
[Example 1]
[Crushing lithium carbonate]
200 g of lithium carbonate having an average particle diameter of 53 μm is cooled to -196 ° C. with liquid nitrogen using a crusher (liquid nitrogen bead mill LNM) manufactured by Imex, and then using dry ice beads at a peripheral speed of 10.0 m / s. Was crushed for 9 minutes. The charged lithium carbonate particle size was determined by measuring the average particle size of the lithium carbonate obtained by preventing thermal denaturation at -196 ° C. and brittle fracture, and found to be 2.0 μm.

[Preparation of positive electrode active material]
[Preparation of activated carbon 1]
The crushed coconut shell carbide was carbonized in nitrogen at 500 ° C. for 3 hours in a small carbonization furnace to obtain carbonized material. The obtained carbide was put into an activation furnace, and 1 kg / h of steam was introduced into the activation furnace in a state of being heated by the preheating furnace, and the temperature was raised to 900 ° C. over 8 hours for activation. The activated carbon was taken out and cooled in a nitrogen atmosphere to obtain activated activated carbon. The obtained activated carbon was washed with water for 10 hours and then drained. Then, after drying in an electric dryer maintained at 115 ° C. for 10 hours, activated carbon 1 was obtained by pulverizing with a ball mill for 1 hour.
As a result of measuring the average particle size of this activated carbon 1 using a laser diffraction type particle size distribution measuring device (SALD-2000J) manufactured by Shimadzu Corporation, it was 4.2 μm. In addition, the pore distribution was measured using a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics. As a result, the BET specific surface area was 2360 m ² / g, the mesopore amount (V1) was 0.52 cc / g, the micropore amount (V2) was 0.88 cc / g, and V1 / V2 = 0.59.

[Preparation of activated carbon 2]
The phenol resin was carbonized in a firing furnace at 600 ° C. for 2 hours in a nitrogen atmosphere, then pulverized with a ball mill and classified to obtain a carbide having an average particle diameter of 7.0 μm. This carbide and KOH were mixed at a mass ratio of 1: 5, and activated by heating in a firing furnace at 800 ° C. for 1 hour in a nitrogen atmosphere. Then, activated carbon 2 was obtained by stirring and washing in dilute hydrochloric acid adjusted to a concentration of 2 mol / L for 1 hour, boiling and washing with distilled water until the pH became stable between 5 and 6, and then drying.
The average particle size of this activated carbon 2 was measured using a laser diffraction type particle size distribution measuring device (SALD-2000J) manufactured by Shimadzu Corporation and found to be 7.1 μm. The pore distribution was measured using a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics. As a result, the BET specific surface area was 3627 m ² / g, the mesopore amount (V1) was 1.50 cc / g, the micropore amount (V2) was 2.28 cc / g, and V1 / V2 = 0.66.

[Preparation of positive electrode coating liquid]
Using the activated carbon 1 or 2 obtained above as the positive electrode active material and the lithium carbonate obtained above as the charged lithium compound, a positive electrode coating liquid was produced by the following method.
59.5 parts by mass of activated carbon 1 or 2, 28.0 parts by mass of lithium carbonate, 3.0 parts by mass of Ketjen Black, 1.5 parts by mass of PVP (polyvinylidene), and PVDF (polyvinylidene fluoride). 8.0 parts by mass and NMP (N-methylpyrrolidone) are mixed, and the mixture is dispersed and coated under the condition of peripheral speed of 17.0 m / s using a thin film swirling high-speed mixer fill mix manufactured by PRIMIX. Obtained liquid.

[Preparation of positive electrode precursor]
The above coating liquid is applied to one or both sides of an aluminum foil having a thickness of 15 μm using a die coater manufactured by Toray Engineering Co., Ltd. at a coating speed of 1 m / s, and dried at a drying temperature of 100 ° C. to obtain a positive electrode precursor. Obtained. The obtained positive electrode precursor was pressed using a roll press machine under the conditions of a pressure of 4 kN / cm and a surface temperature of the press portion of 25 ° C.

[Solid ⁷ Li-NMR measurement]
For the positive electrode of the obtained non-aqueous lithium-type power storage element, solid ⁷ Li-NMR measurement of the positive electrode active material layer was performed.
First, for the non-aqueous lithium-type power storage element manufactured above, a constant current of up to 2.9 V at a current of 50 mA at an ambient temperature of 25 ° C. using a charging / discharging device (ACD-01) manufactured by Asuka Electronics. After charging, constant current constant voltage charging was performed for 2 hours by applying a constant voltage of 2.9 V.
Next, the positive electrode active material layer was collected in an argon atmosphere. The non-aqueous lithium storage element was disassembled in an argon atmosphere, and the positive electrode was taken out. Subsequently, the obtained positive electrode was immersed in diethyl carbonate for 2 minutes or more to remove lithium salts and the like. After another immersion in diethyl carbonate under the same conditions, it was air-dried. Then, the positive electrode active material layer was collected from the positive electrode.
Using the obtained positive electrode active material layer as a sample, solid ⁷ Li-NMR measurement was performed. Using JEOL RESONANCE ECA700 (resonance frequency of ⁷ Li-NMR is 272.1 MHz) as a measuring device, the rotation speed of magic angle spinning is 14.5 kHz and the irradiation pulse width is 45 ° pulse in a room temperature environment. , Measured by the single pulse method. The observation range was in the range of -400 ppm to 400 ppm, and the number of points was 4096 points. After all other measurement conditions other than the repetition waiting time, such as the number of integrations and the receiver gain, are set to be the same, measurements are performed when the repetition waiting time is 10 seconds and 3000 seconds, respectively, and an NMR spectrum is obtained. It was. A 1 mol / L lithium chloride aqueous solution was used as a shift reference, and the shift position measured separately as an external standard was set to 0 ppm. When measuring the lithium chloride aqueous solution, the sample was not rotated, and the irradiation pulse width was set to 45 ° pulse, and the measurement was performed by the single pulse method.
The b / a was calculated from the solid ⁷ Li-NMR spectrum of the positive electrode active material layer obtained by the above method by the above method and found to be 5.7.

[Preparation of negative electrode active material]
[Preparation of active material]
Instead of the composite carbon material A, artificial graphite having an average particle diameter of 4.9 μm was used as a base material, the amount of coal-based pitch used was 50 g, and the heat treatment temperature was 1000 ° C. The composite carbon material B was produced and evaluated. As a result, the BET specific surface area of the composite carbon material B was 6.1 m ² / g. The mass ratio of the carboniferous material derived from the carboniferous pitch to artificial graphite was 2%.

[Manufacturing of negative electrode]
A negative electrode was manufactured using the composite carbon material B obtained above as a negative electrode active material.
80 parts by mass of composite carbon material B, 8 parts by mass of acetylene black, 12 parts by mass of PVdF (polyvinylidene fluoride), and NMP (N-methylpyrrolidone) are mixed, and the thin film swirl type high speed manufactured by PRIMIX Corporation is mixed. A coating liquid was obtained by dispersing using a mixer fill mix under the condition of a peripheral speed of 15 m / s. The viscosity (ηb) and TI value of the obtained coating liquid were measured using an E-type viscometer TVE-35H manufactured by Toki Sangyo Co., Ltd. As a result, the viscosity (ηb) was 2,798 mPa · s, and the TI value was 2.7. The above coating liquid was applied to both sides of an electrolytic copper foil having a thickness of 10 μm and having no through holes using a die coater manufactured by Toray Engineering Co., Ltd. at a coating speed of 1 m / s, and dried at a drying temperature of 85 ° C. Obtained a negative electrode. The obtained negative electrode was pressed using a roll press machine under the conditions of a pressure of 4 kN / cm and a surface temperature of the press portion of 25 ° C. The film thickness of the negative electrode active material layer of the negative electrode obtained above was measured from the average value of the thickness measured at any 10 points of the negative electrode using a film thickness meter Linear Gauge Sensor GS-551 manufactured by Ono Keiki Co., Ltd. It was calculated by subtracting the thickness of the foil. As a result, the film thickness of the negative electrode active material layer was 25 μm per one side.

[Adjustment of electrolyte]
As an organic solvent, a mixed solvent of ethylene carbonate (EC): methyl ethyl carbonate (EMC) = 40: 60 (volume ratio) was used, and the concentration ratio of LiN (SO ₂ F) ₂ and LiPF _{6 to} the total electrolytic solution was A solution obtained by dissolving each electrolyte salt so that the sum of the concentrations of LiN (SO ₂ F) ₂ and LiPF ₆ is 1.2 mol / L at 50:50 (molar ratio) is non-aqueous electrolysis. Used as a liquid.
The concentrations of LiN (SO ₂ F) ₂ and LiPF ₆ in the electrolytic solution prepared here were 0.6 mol / L and 0.6 mol / L, respectively.

[Preparation of non-aqueous lithium-type power storage element]
[Assembly process]
The obtained double-sided negative electrode was cut into 12.2 cm × 450 cm, and the double-sided positive electrode precursor was cut into 12.0 cm × 300 cm. The negative electrode and the positive electrode precursor each have an uncoated portion. This uncoated portion was formed so as to have a width of 2 cm from the end side. A microporous membrane separator having a thickness of 15 μm is sandwiched so that the uncoated portions are in opposite directions, and the uncoated portion is wound in an elliptical shape so as to protrude from the separator, and the wound body is pressed. Molded into a flat shape. Then, the electrode terminals were bonded to the negative electrode and the positive electrode precursor by ultrasonic welding to form an electrode wound body. This electrode winding body was housed in an exterior body made of an aluminum laminated packaging material, and the three outer bodies of the electrode terminal portion and the bottom portion were heat-sealed under the conditions of a temperature of 180 ° C., a sealing time of 20 seconds, and a sealing pressure of 1.0 MPa. .. This was vacuum dried at a temperature of 80 ° C. and a pressure of 50 Pa under the conditions of a drying time of 60 hr.

[Liquid injection, impregnation, sealing process]
Approximately 80 g of the non-aqueous electrolyte solution was injected under atmospheric pressure into the electrode winding body housed in the aluminum laminate packaging material in a dry air environment at a temperature of 25 ° C. and a dew point of −40 ° C. or lower. Subsequently, the non-aqueous lithium-type power storage element was placed in the decompression chamber, the pressure was reduced from normal pressure to −87 kPa, the pressure was returned to atmospheric pressure, and the mixture was allowed to stand for 5 minutes. Then, the pressure was reduced from normal pressure to −87 kPa, the process of returning to atmospheric pressure was repeated 4 times, and then the mixture was allowed to stand for 15 minutes. Further, the pressure was reduced from normal pressure to -91 kPa, and then returned to atmospheric pressure. Similarly, the steps of depressurizing and returning to atmospheric pressure were repeated 7 times in total (reduced pressure to -95, -96, -97, -81, -97, -97, and -97 kPa, respectively). Through the above steps, the electrode laminate was impregnated with the non-aqueous electrolyte solution.
Then, the non-aqueous lithium-type power storage element was placed in a vacuum sealing machine, and the aluminum laminate packaging material was sealed by sealing at 180 ° C. for 10 seconds at a pressure of 0.1 MPa with the pressure reduced to −95 kPa.

[Lithium doping process]
The obtained non-aqueous lithium-type power storage element is charged with a constant current using a charging / discharging device (TOSCAT-3100U) manufactured by Toyo Systems Co., Ltd. in a 25 ° C environment at a current value of 1000 mA until a voltage of 4.5 V is reached. After that, the initial charge was continuously performed by a method of continuing 4.5 V constant voltage charging for 72 hours, and lithium doping was performed on the negative electrode. Further, the non-opposing portion of the negative electrode was masked in advance with a polyethylene film at the time of assembly to prevent the non-opposing portion from being doped with lithium ions.

[Aging process]
The non-aqueous lithium power storage element after lithium doping is subjected to constant current discharge at 1.0 A in a 25 ° C environment until the voltage reaches 3.0 V, and then 3.0 V constant current discharge is performed for 1 hour to increase the voltage. Adjusted to 3.0V. Then, the non-aqueous lithium-type power storage element was stored in a constant temperature bath at 60 ° C. for 60 hours.

[Degassing process]
A part of the aluminum laminate packaging material was opened in a dry air environment at a temperature of 25 ° C. and a dew point of −40 ° C. for the aged non-aqueous lithium-type power storage element. Next, after removing the masking attached to the non-opposing portion of the negative electrode, the non-aqueous lithium-type power storage element was placed in the decompression chamber, and a diaphragm pump (N816.3KT.45.18) manufactured by KNF was used. After depressurizing from atmospheric pressure to −80 kPa over 3 minutes, the process of returning to atmospheric pressure over 3 minutes was repeated a total of 3 times. Then, a non-aqueous lithium-type power storage element was placed in a vacuum sealing machine, the pressure was reduced to −90 kPa, and then the aluminum laminate packaging material was sealed by sealing at 200 ° C. for 10 seconds at a pressure of 0.1 MPa.
Through the above steps, the non-aqueous lithium-type power storage element was completed.

[Evaluation of power storage element]
[Measurement of negative electrode potential between facing and non-facing parts]
The power storage element was disassembled in an argon atmosphere, and the portion of the taken-out negative electrode where both sides of the negative electrode faced each other was cut out with ceramic scissors. Next, metallic lithium wrapped in a polyolefin-based separator, which is a reference electrode, was pressed against the metal, and the same electrolytic solution used for the power storage element was dropped. After that, the potential difference between the reference electrode and the uncoated portion (copper foil) of the negative electrode in a well-impregnated state was measured with a tester and found to be 200 mV. The portion where both sides of the negative electrode are non-opposing portions was also cut out and measured in the same manner, and it was 1800 mV. Therefore, the potential difference between the facing portion and the non-opposing portion was 1600 mV.

[Calculation of lithium ion concentration in facing and non-opposing parts]
The power storage element was disassembled in an argon atmosphere, and the portion where both sides of the negative electrode faced each other and the portion where both sides of the negative electrode faced each other were cut out with ceramic scissors, and each negative electrode active material layer was solid ⁷ Li-NMR. The spectrum was measured. Calculate the amount of lithium per unit mass of the negative electrode active material layer that has a maximum peak value between 4 ppm and 30 ppm in the spectrum range of -10 ppm to 35 ppm and occludes lithium ions calculated from the peak area of 4 ppm to 30 ppm. Then, the ratio of the lithium ion occluded in the negative electrode was calculated by dividing the amount of lithium in the non-opposing portion by the amount of lithium in the facing portion, and it was 0.09.

[Measurement of negative electrode film thickness between facing and non-facing parts]
The power storage element was disassembled in an argon atmosphere, and for the negative electrode taken out, the part where both sides of the negative electrode were opposed and the part where both sides of the negative electrode were non-opposed were the film thickness meters Liner Gauge Sensor GS-551 manufactured by Ono Keiki Co., Ltd. Was calculated by calculating the average value of the thickness measured at any 10 locations using. From the calculated value, the ratio of the film thickness of the non-opposing portion to the film thickness of the facing portion was 0.82.

[Calculation of energy density]
In a constant temperature bath set at 25 ° C., a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Limited is used to perform constant current charging until the current value of 2C reaches 3.8V, followed by constant current charging. A constant voltage charge of applying a constant voltage of 3.8 V was performed for a total of 30 minutes. After that, let Q be the capacitance when constant current discharge is performed with a current value of 2C up to 2.2V, and use the capacitance F (F) calculated by F = Q / (3.8-2.2). The energy density was calculated by E / V ₁ = F × (3.8 ² -2.2 ² ) / 2/3600 / V and found to be 32.8 Wh / L.
The volume V ₁ (= l ₁ × w ₁ × t ₁ ) of the power storage element is the outer dimension length (l ₁ ) and outer dimension width (w ₁ ) of the cup-molded portion of the laminate film of the power storage element, and the laminate film. The value obtained by the thickness (t ₁ ) of the power storage element including the value was used.

[Calculation of discharge internal resistance R]
The obtained power storage element is fixed in a constant temperature bath set at 25 ° C. using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Co., Ltd. until it reaches 3.8V at a current value of 20C. Current charging, then constant voltage charging to apply a constant voltage of 3.8V for a total of 30 minutes, then constant current discharge to 2.2V with a current value of 20C, discharge curve (time-voltage) Got In this discharge curve, the voltage at the discharge time = 0 second obtained by extrapolating from the voltage values at the discharge times of 2 seconds and 4 seconds is defined as Eo, the voltage drop ΔE = 3.8-Eo, and The room temperature discharge internal resistance R was calculated by R = ΔE / (20C (current value A)). The obtained room temperature internal resistance R was 2.10 mΩ.

[Rate of increase in internal resistance of normal temperature discharge after high load charge / discharge cycle test]
The obtained power storage element is fixed in a constant temperature bath set at 25 ° C. using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Limited until it reaches 3.8V at a current value of 300C. The charge / discharge step of charging with a current and then performing a constant current discharge with a current value of 300 C until reaching 2.2 V was repeated 60,000 times. After the high load charge / discharge cycle test, the normal temperature discharge internal resistance Re after the high load charge / discharge cycle test was calculated in the same manner as in the above [Calculation of discharge internal resistance R]. The ratio Re / R calculated by dividing this Re (Ω) by the internal resistance R (Ω) before the high load charge / discharge cycle test obtained in the above [Calculation of discharge internal resistance R] was 1.21. ..

[Capacity recovery rate after high load charge / discharge cycle test]
The obtained power storage element is fixed in a constant temperature bath set at 25 ° C. using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Limited until it reaches 3.8V at a current value of 300C. The charge / discharge step of charging with a current and then performing a constant current discharge with a current value of 300 C until reaching 2.2 V was repeated 60,000 times. After the end of the cycle, the battery was charged to 4.5 V with a current value of 20 C, and then constant voltage charging was continued for 1 hour. The value obtained by measuring the subsequent capacitance Fe and dividing by the capacitance F before the high load charge / discharge cycle was Fe / F = 0.84.

[Examples 2-28 and Comparative Examples 1-6]
The non-aqueous lithium-type storage devices of Examples 2 to 28 and Comparative Examples 1 to 6 were similarly manufactured in the same manner as in Example 1 except that the manufacturing conditions of the non-aqueous lithium storage elements were as shown in Table 1 below. Each element was manufactured and various evaluations were performed. The evaluation results of the obtained non-aqueous lithium-type power storage element are shown in Table 2 below. In addition, supplementary preparation conditions for Comparative Examples 1 to 6 are described below.

[Supplement to Comparative Example 1 and Comparative Example 2]
[assembly]
A lithium metal leaf corresponding to 350 mAh / g per unit mass of the negative electrode active material was attached to the non-opposing portion of the negative electrode in advance, and the power storage element was assembled in the same manner as in Example 1.

[Lithium doping process]
In addition to changing the current value to 50 mA for the obtained power storage element, after performing lithium doping in the same manner as in Example 1, the negative electrode was lithium-doped by leaving it in a constant temperature bath set at 45 ° C. for 21 hours. Was done.

[Supplement to Comparative Examples 3 to 6]
[assembly]
A lithium metal leaf corresponding to 350 mAh / g per unit mass of the negative electrode active material was attached to both sides of the negative electrode in advance, and a power storage element was assembled in the same manner as in Example 1.

[Lithium doping process]
The obtained power storage element was left to stand for 21 hours in a constant temperature bath set at 45 ° C. to perform lithium doping on the negative electrode.

[Evaluation criteria]
[Discharge internal resistance]
The result of the discharge internal resistance (mΩ) was evaluated as follows.
AA: 2.00 or less A: 2.00 or more and 2.50 or less B: 2.50 or more and 3.00 or less C: 3.00 or more

[Energy density]
The results of energy density (Wh / L) were evaluated as follows.
AA: 33.0 or more A: 28.0 or more and less than 33.0 B: 21.0 or more and less than 28.0 C: less than 21.0

[Internal resistance increase rate during charge / discharge cycle]
The results of the internal resistance increase rate during the charge / discharge cycle were evaluated as follows.
AA: 1.25 or less A: 1.25 or more and 1.50 or less B: 1.50 or more and 2.00 or less C: 2.00 or more

[Capacity recovery rate during charge / discharge cycle]
The results of the capacity recovery rate during the charge / discharge cycle were evaluated as follows.
AA: 0.85 or more A: 0.80 or more and less than 0.85 B: 0.75 or more and less than 0.80 C: less than 0.75

The evaluation results of Examples 1 to 4 were all A, and the evaluation results of Examples 5 to 28 were all AA. From the results of the above examples, it can be seen that the non-aqueous lithium storage device of the present invention can provide excellent energy density, high input / output characteristics, and durability against a high load charge / discharge cycle.

The non-aqueous lithium type power storage element of the present invention is suitable, for example, in the field of a hybrid drive system in which an internal combustion engine, a fuel cell, or a motor in an automobile and a power storage element are combined; as an assist power source application at a peak of instantaneous power. Can be used for.

1 Winding body 2 Double-sided positive electrode 3 Double-sided negative electrode 4 Separator 5 Disassembling side view of the wound body 6 Double-sided positive electrode 7 Double-sided negative electrode 8 Separator 9 Opposing part 10 Non-opposing part 11 Non-opposing part cut out from the negative electrode 12 Divided during potential gradient measurement Non-opposing part

Claims (5)

A non-aqueous lithium-type power storage element composed of a positive electrode containing a lithium compound other than an active material, a negative electrode, a separator, and a non-aqueous electrolyte solution containing lithium ions.
The positive electrode has a positive electrode current collector, a positive electrode active material layer composed of an active material and a lithium compound is provided on the positive electrode current collector, and the negative electrode has a negative electrode current collector and the negative electrode. It contains an active material that can store and release lithium ions on the current collector, and further
The positive electrode and the negative electrode consist of an electrode wound body wound via a separator, and in addition,
The negative electrode has a portion facing the positive electrode and the negative electrode facing each other with the separator interposed therebetween.
With the separator interposed therebetween, it has a non-opposing portion in which the opposite positive electrode does not exist, and
The negative electrode potential in the non-opposing section, rather high above 50mV than the negative electrode potential at the opposing portions,
A non-aqueous lithium-type power storage element in which the lithium compound is at least one lithium compound selected from the group consisting of lithium carbonate, lithium oxide, and lithium hydroxide . The non-aqueous lithium-type power storage element according to claim 1, wherein the negative electrode active material layer in the non-opposing portion has a negative electrode potential gradient of 500 mV / m or more. Claim 1 or 2 in which the ratio of the lithium ion concentration (mass%) in the negative electrode active material of the non-opposing portion to the lithium ion concentration (mass%) in the negative electrode active material of the facing portion is 0.85 or less. The non-aqueous lithium-type power storage element described in 1. The ratio of the film thickness of the negative electrode of the non-opposing portion to the film thickness of the negative electrode of the facing portion is
The non-aqueous lithium-type power storage element according to any one of claims 1 to 3, which is 0.80 or more and 0.95 or less. In the non-aqueous lithium-type power storage element according to any one of claims 1 to 4 , the initial capacitance of the non-aqueous lithium-type power storage element during the charge / discharge cycle is F (F), and the room temperature discharge internal resistance is set. Ra (Ω), environmental temperature 25 ° C, cell voltage from 2.2V to 3.8V, capacitance after 60,000 high-load charge / discharge cycles at a rate of 300C Fe (F) ) When the internal resistance of room temperature discharge is Re (Ω), the following:
(A) Re / Ra is 0.90 or more and 1.5 or less;
(B) The non-aqueous lithium-type power storage element having Fe / F of 0.80 or more at the same time.

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