JP2018056410A - Nonaqueous lithium power storage element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the decomposition of a lithium compound in a positive electrode in high-load charge and discharge cycles to suppress the rise in resistance and the gas generation in a nonaqueous lithium power storage element including an electrode body wound in a flat form.SOLUTION: A nonaqueous lithium power storage element comprises a flat wound electrode body (2). Supposing that a quantity of a lithium compound in a positive electrode active material layer is C(g/m) in a curved portion (4) of the positive electrode active material layer disposed in an outermost layer of the flat wound electrode body, and a quantity of the lithium compound in the positive electrode active material layer is C(g/m) in a flat portion (3) of the positive electrode active material layer disposed in the outermost layer of the flat wound electrode body (2), Cand Care each 0.1 or more and 20 or less, and C/Cis 0.25 or more and 0.95 or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a non-aqueous lithium storage element.

In recent years, from the viewpoint of the conservation of the global environment and the effective use of energy aimed at saving resources, wind power generation smoothing system or midnight power storage system, home-use distributed storage system based on solar power generation technology, storage for electric vehicles The system is drawing attention.
The first requirement for batteries used in these power storage systems is high energy density. As a promising candidate for a high energy density battery capable of meeting such demands, development of a lithium ion battery has been vigorously advanced.
The second requirement is high output characteristics. For example, 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) requires a power storage system that exhibits high output discharge characteristics during acceleration. Has been.
Currently, electric double layer capacitors, nickel metal hydride batteries, and the like have been developed as high-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 not only has high output characteristics, but also has high durability (cycle characteristics and high-temperature storage characteristics), and has been considered to be an optimum device in the field where the above high output is required. However, the energy density is only about 1 to 5 Wh / L. Therefore, further improvement in energy density is necessary.
On the other hand, nickel-metal hydride batteries that are currently generally used in hybrid electric vehicles have a high output equivalent to that of electric double layer capacitors and an energy density of about 160 Wh / L. However, research for increasing the energy density and output characteristics and increasing durability (particularly stability at high temperatures) has been energetically advanced.
In addition, research for higher output is also being conducted in lithium ion batteries. For example, a lithium ion battery has been developed that can obtain a high output exceeding 3 kW / L at a depth of discharge (that is, a ratio (%) of a discharge amount to a discharge capacity of a storage element) of 50%. However, the energy density is 100 Wh / L or less, which is a design that dares to suppress the high energy density, which is the greatest feature of the lithium ion battery. Further, its durability (cycle characteristics and high temperature storage characteristics) is inferior to that of an electric double layer capacitor. Therefore, such a lithium ion battery is used in a range where the depth of discharge is narrower than the range of 0 to 100% in order to have practical durability. Since the capacity that can actually be used is further reduced, research for further improving the durability is being actively pursued.

As described above, there is a strong demand for the practical use of a power storage device having high energy density, high output characteristics, and high 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 demanded. As a promising candidate, a storage element called a lithium ion capacitor has attracted attention and has been actively developed.
A lithium ion capacitor is a kind of power storage element that uses a non-aqueous electrolyte containing a lithium salt (hereinafter also referred to as “non-aqueous lithium power storage element”). It is a power storage element that charges and discharges by the same non-Faraday reaction by adsorption and desorption of anions, and by the Faraday reaction by occlusion and release of lithium ions in the negative electrode similar to a lithium ion battery.

The electrode materials generally used for the above-mentioned power storage elements and their characteristics are summarized. Generally, materials such as activated carbon are used for the electrodes, and charge and discharge are performed by adsorption and desorption (non-Faraday reaction) of ions on the activated carbon surface. When it is performed, high output and high durability can be obtained, but the energy density is lowered (for example, 1 time). On the other hand, when an oxide or a carbon material is used for the electrode and charging / discharging is performed by a Faraday reaction, the energy density is increased (for example, 10 times that of a non-Faraday reaction using activated carbon), but durability and output are increased. There is a problem in characteristics.
As a combination of these electrode materials, the electric double layer capacitor is characterized in that activated carbon (energy density is 1 time) is used for the positive and negative electrodes, and both the positive and negative electrodes are charged and discharged by a non-Faraday reaction, and therefore, high output and high durability. However, the energy density is low (positive electrode 1 ×× negative electrode 1 = 1).
The lithium ion secondary battery is characterized in that a lithium transition metal oxide (energy density 10 times) is used for the positive electrode, a carbon material (energy density 10 times) is used for the negative electrode, and both the positive and negative electrodes are charged and discharged by a Faraday reaction. Although it has a high energy density (positive electrode 10 times × negative electrode 10 times = 100), there are problems in output characteristics and durability. Furthermore, in order to satisfy the high durability required for a hybrid electric vehicle or the like, the depth of discharge must be limited, and in the lithium ion secondary battery, only 10 to 50% of the energy can be used.

  A lithium ion capacitor is characterized by using activated carbon (energy density 1 time) for the positive electrode and a carbon material (10 times energy density) for the negative electrode, and charging and discharging by non-Faraday reaction at the positive electrode and Faraday reaction at the negative electrode. It is an asymmetric capacitor having the characteristics of an electric double layer capacitor and a lithium ion secondary battery. And although a lithium ion capacitor has high output and high durability, it has a high energy density (positive electrode 1 ×× negative electrode 10 = 10), and there is no need to limit the depth of discharge unlike a lithium ion secondary battery. It is a feature.

Various studies have been conducted on the positive electrode of the above-described power storage element (particularly, a lithium ion secondary battery).
Patent Document 1 proposes a lithium ion secondary battery using a positive electrode containing lithium carbonate in the positive electrode and having a current interruption mechanism that operates in accordance with an increase in the internal pressure of the battery. Patent Document 2 proposes a lithium ion secondary battery in which a lithium composite oxide such as lithium manganate is used as a positive electrode, and lithium carbonate is contained in the positive electrode to suppress elution of manganese. Patent Document 3 proposes a method for recovering the capacity of a deteriorated power storage element by oxidizing various lithium compounds as oxides at the positive electrode. However, the positive electrodes described in Patent Documents 1 to 3 still have room for improvement with respect to application to asymmetric capacitors such as lithium ion capacitors. In particular, in a high-load charge / discharge cycle of a non-aqueous lithium storage element, a lithium compound in the positive electrode There has been no study on the suppression of gas decomposition and the suppression of gas generation and resistance increase.

JP 7-328278 A JP 2001-167767 A JP 2012-174437 A

  In view of the above situation, the problem to be solved by the present invention is that the temperature of the flat part of the electricity storage element rises due to a high-load charge / discharge cycle in a non-aqueous lithium electricity storage element comprising an electrode body wound in a flat shape. In some cases, gas generation is suppressed by suppressing decomposition of the lithium compound in the positive electrode.

The above problem is solved by the following technical means.
That is, the present invention is as follows:
[1]
A flat winding comprising at least one positive electrode containing a lithium compound other than the active material, at least one negative electrode, and at least one separator, and winding the positive electrode and the negative electrode in a flat shape through the separator. An electrode body; and a non-aqueous electrolyte containing lithium ions;
A non-aqueous lithium storage element comprising:
On the positive electrode current collector of the positive electrode, at least one positive electrode active material layer composed of the active material and the lithium compound is applied,
On the negative electrode current collector of the negative electrode, at least one negative electrode active material layer made of a negative electrode active material capable of inserting and extracting lithium ions is applied, and among the positive electrodes, the flat wound electrode body In the positive electrode disposed in the outermost layer, the amount of the lithium compound in the curved portion of the positive electrode active material layer facing the negative electrode active material layer is C _x1 (g / m ² ), and the positive electrode active material layer When the amount of the lithium compound in the flat portion is C _y1 (g / m ² ), C _x1 and C _y1 are 0.1 or more and 20 or less, respectively, and C _y1 / C _x1 is 0.25 or more and _0.00 . 95 or less,
The non-aqueous lithium storage element.
[2]
When the basis weight of the positive electrode active material layer in the curved portion is C _x2 (g / m ² ) and the basis weight of the positive electrode active material layer in the flat portion is C _y2 (g / m ² ), C _x2 / C The nonaqueous lithium storage element according to [1], wherein _y2 is 0.85 or more and 1.15 or less.
[3]
The non-aqueous lithium storage element according to [1] or [2], wherein the lithium compound is lithium carbonate, lithium oxide, or lithium hydroxide.
[4]
The positive electrode active material contained in the positive active material layer provided on one surface or on both surfaces of a positive electrode current collector, V ₁ mesopores amount derived from the pores below the calculated diameter 20Å or 500Å where the BJH method (Cc / g), where V < ₂ (cc / g) is the amount of micropores derived from pores having a diameter of less than 20 mm calculated by the MP method, 0.3 <V ₁ ≦ 0.8 and 0.5 Any of [1] to [3], which is activated carbon that satisfies ≦ V ₂ ≦ 1.0 and has a specific surface area measured by the BET method of 1,500 m ² / g or more and 3,000 m ² / g or less. The non-aqueous lithium storage element according to claim 1.
[5]
The positive electrode active material contained in the positive electrode active material layer has a mesopore amount V ₁ (cc / g) derived from pores having a diameter of 20 to 500 mm calculated by BJH method of 0.8 <V ₁ ≦ 2.5. The ratio of micropores V ₂ (cc / g) derived from pores having a diameter of less than 20 mm calculated by the MP method satisfying 0.8 <V ₂ ≦ 3.0 and measured by the BET method The nonaqueous lithium storage element according to any one of [1] to [3], which is activated carbon having a surface area of 2,300 m ² / g or more and 4,000 m ² / g or less.
[6]
The non-conducting material according to any one of [1] to [5], wherein a doping amount of the lithium ion with respect to the negative electrode active material is 530 mAh / g or more and 2,500 mAh / g or less per unit mass of the negative electrode active material. Water-based lithium storage element.
[7]
The nonaqueous lithium storage element according to [6], wherein the negative electrode active material has a BET specific surface area of 100 m ² / g or more and 1,500 m ² / g or less.
[8]
The non-aqueous lithium according to any one of [1] to [5], wherein a doping amount of the lithium ion with respect to the negative electrode active material is 50 mAh / g or more and 700 mAh / g or less per unit mass of the negative electrode active material. Power storage element.
[9]
The non-aqueous lithium storage element according to [8], wherein the negative electrode active material has a BET specific surface area of 1 m ² / g or more and 50 m ² / g or less.
[10]
The non-aqueous lithium storage element according to any one of [1] to [9], wherein an average particle diameter of the negative electrode active material is 1 μm or more and 10 μm or less.

  According to the present invention, when the temperature of the flat portion of the electricity storage device rises due to a high load charge / discharge cycle, the non-aqueous lithium electricity storage device suppresses excessive decomposition of the lithium compound contained in the positive electrode and generates less gas. Is provided.

FIG. 1 is a diagram illustrating a range of a curved portion and a flat portion in a cross section of a flat wound electrode body according to an embodiment of the present invention. FIG. 2 is a diagram showing a positive electrode active material layer in a flat portion when the outermost layer of the flat wound electrode body according to the embodiment of the present invention is a positive electrode. FIG. 3 is a diagram showing a positive electrode active material layer in a flat portion when the outermost layer of the flat wound electrode body according to the embodiment of the present invention is a negative electrode.

  Hereinafter, although an embodiment of the present invention (hereinafter referred to as “this embodiment”) will be described in detail, the present invention is not limited to this embodiment. The upper limit value and the lower limit value in each numerical range of the present embodiment can be arbitrarily combined to constitute an arbitrary numerical range.

  In general, a non-aqueous lithium storage element mainly includes a positive electrode, a negative electrode, a separator, and an electrolytic solution. As the electrolytic solution, an organic solvent containing lithium ions (hereinafter also referred to as “non-aqueous electrolytic solution”) is used. The non-aqueous lithium storage element in the present embodiment includes a positive electrode and a flat wound electrode body in which the negative electrode is wound in a flat shape via a separator.

<Positive electrode>
The positive electrode in the present embodiment includes a positive electrode current collector and a positive electrode active material layer including a positive electrode active material provided on one side or both sides thereof. The positive electrode includes a positive electrode current collector and a positive electrode active material layer including a positive electrode active material provided on one side or both sides thereof.
It is preferable that the positive electrode in this embodiment contains lithium compounds other than an active material as a positive electrode precursor before assembling an electrical storage element. As will be described later, in the present embodiment, in the step of assembling the power storage element, it is preferable to pre-dope lithium ions into the negative electrode. As a pre-doping method in the present embodiment, a battery element is assembled using a positive electrode precursor containing a lithium compound, a negative electrode, a separator, and a non-aqueous electrolyte, and then a voltage is applied between the positive electrode precursor and the negative electrode. It is preferable to apply. The lithium compound is preferably contained in a positive electrode active material layer formed on the positive electrode current collector of the positive electrode precursor.
In the present specification, the positive electrode before the lithium doping step is defined as “positive electrode precursor”, and the positive electrode after the lithium doping step is defined as “positive electrode”.

[Positive electrode active material layer]
The positive electrode active material layer includes a positive electrode active material, and may include optional components such as a conductive filler, a binder, and a dispersion stabilizer in addition to this. The positive electrode active material preferably contains a carbon material.
The positive electrode active material layer of the positive electrode precursor preferably contains a lithium compound.

[Positive electrode active material]
The positive electrode active material is a substance that participates in a Faraday reaction or a non-Faraday reaction during charging and discharging of the power storage element, and preferably includes a carbon material. Examples of the carbon material include carbon nanotubes, conductive polymers, and porous carbon materials, and more preferably activated carbon. The positive electrode active material may include a mixture of two or more materials, or may include a material other than a carbon material, such as a composite oxide of lithium and a transition metal.
The content of the carbon material with respect to the total mass of the positive electrode active material is preferably 50% by mass or more, and more preferably 70% by mass or more. Although the content of the carbon material may be 100% by mass, it is preferably 90% by mass or less and may be 80% by mass or less, for example, from the viewpoint of obtaining a good effect when used in combination with other materials. Good.

When using activated carbon as a positive electrode active material, the kind of activated carbon and its raw material are not particularly limited. However, in order to achieve both high input / output characteristics and high energy density, it is preferable to optimally control the pores of the activated carbon. Specifically, the amount of mesopores derived from pores having a diameter of 20 mm or more and 500 mm or less (that is, 200 nm or more and 5000 nm or less) calculated by the BJH method is V ₁ (cc / g), and the diameter calculated by the MP method is less than 20 mm. When the amount of micropores derived from the pores is V ₂ (cc / g),
(1) In order to obtain high input / output characteristics, 0.3 <V ₁ ≦ 0.8 and 0.5 ≦ V ₂ ≦ 1.0 are satisfied, and the specific surface area measured by the BET method is 1 , 500 m ² / g or more and 3,000 m ² / g or less of activated carbon (hereinafter also referred to as “activated carbon 1”) is preferable,
(2) In order to obtain a high energy density, 0.8 <V ₁ ≦ 2.5 and 0.8 <V ₂ ≦ 3.0 are satisfied, and the specific surface area measured by the BET method is 2, Activated carbon (hereinafter also referred to as “activated carbon 2”) of 300 m ² / g or more and 4,000 m ² / g or less is preferable.
Hereinafter, (1) activated carbon 1 and (2) activated carbon 2 will be described individually and sequentially.

(Activated carbon 1)
The mesopore amount V ₁ of the activated carbon 1 is preferably a value larger than 0.3 cc / g from the viewpoint of increasing the input / output characteristics when the positive electrode material is incorporated in the electric storage element. On the other hand, from the viewpoint of suppressing a decrease in the bulk density of the positive electrode, the V ₁ of the activated carbon 1 is preferably 0.8 cc / g or less. V ₁ of the activated carbon 1 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 V ₂ of the activated carbon 1 is preferably 0.5 cc / g or more in order to increase the specific surface area of the activated carbon and increase the capacity. On the other hand, the V ₂ of the activated carbon 1 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. V ₂ of the activated carbon 1 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 ratio of meso Anaryou _{V 1} relative to the micropore volume _{V 2} of activated carbon 1 _(V 1 / V ₂₎ is preferably in the range of _{0.3 ≦ V 1 / V 2 ≦} 0.9. That is, V ₁ / V _{2 of} activated carbon 1 is 0.3 or more from the viewpoint of increasing the ratio of the mesopore amount to the micropore amount to such an extent that the decrease in output characteristics can be suppressed while maintaining a high capacity. Preferably there is. On the other hand, the V ₁ / V ₂ of the activated carbon 1 is 0.9 or less from the viewpoint of increasing the ratio of the micropore amount to the mesopore amount to such an extent that the decrease in capacity can be suppressed while maintaining high output characteristics. It is preferable that The range of V ₁ / V ₂ of the activated carbon 1 is more preferably 0.4 ≦ V ₁ / V ₂ ≦ 0.7, and still more preferably 0.55 ≦ V ₁ / V ₂ ≦ 0.7.

  The average pore diameter of the activated carbon 1 is preferably 17 mm or more, more preferably 18 mm or more, and further preferably 20 mm or more, from the viewpoint of increasing the output of the obtained electricity storage device. From the viewpoint of increasing the capacity, the average pore diameter of the activated carbon 1 is preferably 25 mm 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 of the activated carbon 1 is 1,500 m ² / g or more, a good energy density is easily obtained. On the other hand, when the BET specific surface area of the activated carbon 1 is 3,000 m ² / g or less, an electrode Since it is not necessary to add a large amount of binder in order to maintain the strength, the performance per electrode volume is increased.

The activated carbon 1 having the above-described features can be obtained using, for example, the raw materials and processing methods described below.
In this embodiment, the carbon source used as a raw material of the activated carbon 1 is not particularly limited. Examples of the carbon source of the activated carbon 1 include wood-based materials such as wood, wood flour, coconut husk, pulp by-products, bagasse and molasses; peat, lignite, lignite, bituminous coal, anthracite, petroleum distillation residue components, petroleum Fossil raw materials such as pitch, coke and coal tar; 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 Synthetic rubbers such as polybutylene, polybutadiene, and polychloroprene; other synthetic woods, synthetic pulps, and carbides thereof. Among these raw materials, from the viewpoint of mass production and cost, plant raw materials such as coconut shells and wood flour, and their carbides are preferable, and coconut shell carbides are particularly preferable.

As the carbonization and activation methods for producing the activated carbon 1 from these raw materials, 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 employed.
As a method for activating the carbide obtained by the carbonization method, a gas activation method in which firing is performed using an activation gas such as water vapor, carbon dioxide, or oxygen is preferably used. A method using water vapor or carbon dioxide as the activation gas is more preferable.
In this activation method, while supplying the activation gas at a rate of 0.5 to 3.0 kg / h, preferably 0.7 to 2.0 kg / h, the carbide is 3 to 12 hours, preferably 5 to 11 hours, More preferably, the temperature is increased to 800 to 1,000 ° C. over 6 to 10 hours for activation.
Furthermore, prior to the activation treatment of the carbide, the carbide may be activated in advance. In this primary activation, it is usually preferable to activate the gas by firing a carbon material at a temperature of less than 900 ° C. using an activation gas such as water vapor, carbon dioxide, or oxygen.
By appropriately combining the firing temperature and firing time in the carbonization method with the activation gas supply amount, the heating rate and the maximum activation temperature in the activation method, it is possible to produce the activated carbon 1 having the above characteristics, which is preferable in the present embodiment. it can.

  The average particle diameter of the activated carbon 1 is preferably 2 to 20 μm. When the average particle diameter of the activated carbon 1 is 2 μm or more, the capacity per electrode volume tends to increase because the density of the active material layer is high. If the average particle size of the activated carbon 1 is small, the durability may be low. However, if the average particle size is 2 μm or more, the durability is difficult to decrease. When the average particle size of the activated carbon 1 is 20 μm or less, it tends to be easily adapted to high-speed charge / discharge. The average particle diameter of the activated carbon 1 is more preferably 2 to 15 μm, and further preferably 3 to 10 μm.

(Activated carbon 2)
The mesopore amount V ₁ of the activated carbon 2 is preferably a value larger than 0.8 cc / g from the viewpoint of increasing the output characteristics when the positive electrode material is incorporated in the power storage element, while reducing the capacity of the power storage element. From the viewpoint of suppression, it is preferably 2.5 cc / g or less. V ₁ of the activated carbon 2 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.

The micropore amount V ₂ of the activated carbon ₂ is preferably a value larger than 0.8 cc / g in order to increase the specific surface area of the activated carbon and increase the capacity. From the viewpoint of increasing the density of the activated carbon as an electrode and increasing the capacity per unit volume, the V ₂ of the activated carbon 2 is preferably 3.0 cc / g or less. V ₂ of the activated carbon 2 is more preferably greater than 1.0 cc / g and not greater than 2.5 cc / g, and still more preferably not less than 1.5 cc / g and not greater than 2.5 cc / g.

The activated carbon 2 having the above-described mesopore size and micropore size has a higher BET specific surface area than 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, and is 3,000 m ² / g or more and 4,000 m ² / g or less. More preferably, it is 3,200 m ² / g or more and 3,800 m ² / g or less. When the BET specific surface area of the activated carbon 2 is 2,300 m ² / g or more, a good energy density is easily obtained, and when the BET specific surface area of the activated carbon 2 is 4,000 m ² / g or less, the strength of the electrode Since it is not necessary to add a large amount of binder in order to maintain the resistance, the performance per electrode volume increases.

The activated carbon 2 having the characteristics as described above can be obtained by using, for example, raw materials and processing methods as described below.
The carbonaceous material used as a raw material for the activated carbon 2 is not particularly limited as long as it is a carbon source that is usually used as a raw material for activated carbon. Examples include fossil raw materials such as coke; various synthetic resins such as phenol resin, furan resin, vinyl chloride resin, vinyl acetate resin, melamine resin, urea resin, and resorcinol resin. Among these raw materials, phenol resin and furan resin are particularly preferable because they are suitable for producing activated carbon 2 having a high specific surface area.
Examples of the method for carbonizing these raw materials or the heating method during the 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. The atmosphere at the time of heating is an inert gas such as nitrogen, carbon dioxide, helium, or argon, or a gas mixed with other gases containing these inert gases as a main component. A method of firing at a carbonization temperature of about 400 to 700 ° C. and a carbonization time of about 0.5 to 10 hours is common.
Examples of the activation method of the carbide after the carbonization treatment include a gas activation method of firing using an activation gas such as water vapor, carbon dioxide, and oxygen, and an alkali metal activation method of performing heat treatment after mixing with an alkali metal compound. In order to produce activated carbon with a high specific surface area, an alkali metal activation method is preferred.

In this activation method, the mass ratio of the carbide and the alkali metal hydroxide such as KOH or NaOH is 1: 1 or more (the amount of the alkali metal hydroxide is equal to or greater than the amount of the carbide) After mixing in such a manner, heating is carried out in the range of 600 to 900 ° C. in an inert gas atmosphere for 0.5 to 5 hours, and then the alkali metal compound is washed and removed with an acid and water, followed by further drying. preferable.
In order to increase the amount of micropores and not increase the amount of mesopores, a larger amount of carbides may be mixed with KOH when activated. In order to increase both the amount of micropores and the amount of mesopores, a larger amount of KOH may be used. In order to mainly increase the amount of mesopores, it is preferable to perform water vapor activation after alkali activation treatment.
The average particle diameter of the activated carbon 2 is preferably 2 μm or more and 20 μm or less, more preferably 3 μm or more and 10 μm or less.

(Use mode of activated carbon)
Each of the activated carbons 1 and 2 may be a single activated carbon or a mixture of two or more activated carbons, and may exhibit the above characteristics as a whole mixture.
The activated carbons 1 and 2 may be used by selecting any one of them, or may be used by mixing both.

The positive electrode active material, activated carbon 1 and 2 other than the materials, for example, active carbon not having the specific V ₁ and / or V _2, or material other than the activated carbon, for example, a composite oxide or the like of lithium and transition metal May be included. In the illustrated embodiment, the content of the activated carbon 1, or the content of the activated carbon 2, or the total content of the activated carbons 1 and 2, is preferably more than 50% by mass of the total positive electrode active material, and 70% by mass or more. More preferably, 90 mass% or more is still more preferable, and it is still more preferable that it is 100 mass%.
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. As a minimum of the content rate of a positive electrode active material, it is more preferable that it is 45 mass% or more, and it is further more preferable that it is 55 mass% or more. On the other hand, as an upper limit of the content rate of a positive electrode active material, it is more preferable that it is 90 mass% or less, and it is still more preferable that it is 85 mass% or less. By setting the content ratio of the positive electrode active material within this range, suitable charge / discharge characteristics are exhibited.

(Lithium compound)
In this specification, a lithium compound means a substance containing lithium, but excludes an active material involved in a Faraday reaction or a non-Faraday reaction in an electrode during charge / discharge of a storage element.
As the lithium compound in the present embodiment, one type selected from lithium carbonate, lithium oxide, lithium hydroxide, lithium fluoride, lithium chloride, lithium oxalate, lithium iodide, lithium nitride, lithium oxalate, and lithium acetate. The above is preferably used. Among these, 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 is decomposed by the application of a voltage, functions as a lithium-doped dopant source for the negative electrode, and forms vacancies in the positive electrode active material layer, so that it has excellent electrolyte retention and ion conductivity. Can be formed. In addition to the lithium compound, one or more alkali metal carbonates selected from sodium carbonate, potassium carbonate, rubidium carbonate, and cesium carbonate can also be used. In the case where an electrolytic solution in which a lithium salt such as LiPF ₆ described later is dissolved in advance is used as the non-aqueous electrolytic solution, the alkali metal carbonate can be used alone. The lithium compound contained in the positive electrode precursor may be one kind, may contain two or more kinds of lithium compounds, and may be used by mixing a lithium compound and another alkali metal carbonate.
In addition, the positive electrode precursor of the present embodiment only needs to contain at least one lithium compound. In addition to the lithium compound, M in the following formula is one or more selected from Na, K, Rb, and Cs. ,
Oxides such as M ₂ O,
Hydroxides such as MOH,
Halides such as MF and MCl,
Oxalates such as M ₂ (CO ₂ ) ₂ ,
One or more carboxylates such as RCOOM (wherein R is H, an alkyl group, or an aryl group) may be included.
Also, the positive electrode _{precursor, BeCO 3, MgCO 3, CaCO} 3, SrCO 3, or an alkaline earth metal carbonate selected from BaCO _3, as well as alkaline earth metal oxides, alkaline earth metal hydroxides, alkaline earth One or more metal halides, alkaline earth metal oxalates, and alkaline earth metal carboxylates may be included.

  The positive electrode precursor according to the present embodiment can include fine particles of a lithium compound. Various methods can be used for micronization of the lithium compound. For example, a pulverizer such as a ball mill, a bead mill, a ring mill, a jet mill, or a rod mill can be used.

(Other components of the positive electrode active material layer)
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 as necessary.

Examples of the conductive filler include a conductive carbonaceous material having higher conductivity than the positive electrode active material. As the conductive filler, for example, ketjen black, acetylene black, vapor grown carbon fiber, graphite, carbon nanotube, a mixture thereof and the like are preferable.
The amount of the conductive filler mixed in the positive electrode active material layer is preferably more than 0 to 20 parts by mass and more preferably in the range of 1 to 15 parts by mass with respect to 100 parts by mass of the positive electrode active material. From the viewpoint of high input, the positive electrode active material layer preferably contains a conductive filler. When the mixing amount of the conductive filler in the positive electrode active material layer is 20 parts by mass or less, the content ratio of the positive electrode active material in the positive electrode active material layer increases, and the energy density per volume of the positive electrode active material layer can be secured.

  The binder is not particularly limited. 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 still more 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. Or less. When the amount of the binder is 1% 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 hindering the entry / exit and diffusion of ions to / from the positive electrode active material.

  Although it does not restrict | limit especially as a dispersion stabilizer, For example, PVP (polyvinyl pyrrolidone), PVA (polyvinyl alcohol), a cellulose derivative etc. can be used. The amount of the dispersion stabilizer used is preferably more than 0 parts by mass 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 is 10 parts by mass or less, high input / output characteristics are exhibited without hindering the entry / exit and diffusion of ions to / from the positive electrode active material.

[Positive electrode current collector]
The material constituting the positive electrode current collector in the present embodiment is not particularly limited as long as it is a material that has high electron conductivity and does not easily deteriorate due to elution into the electrolyte solution and reaction with the electrolyte or ions. A foil is preferred. As the positive electrode current collector in the non-aqueous lithium storage element of the present embodiment, an aluminum foil is particularly preferable.
The metal foil may be a normal metal foil having no irregularities or through holes, or a metal foil having irregularities subjected to embossing, chemical etching, electrolytic deposition, blasting, etc., expanded metal, punching metal, A metal foil having a through-hole such as an etching foil may be used.
Although 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, for example, 1 to 100 μm is preferable. In addition, when a positive electrode electrical power collector has a hole or an unevenness | corrugation, the thickness of a positive electrode electrical power collector shall be measured based on the part where a hole or an unevenness | corrugation does not exist.

[Production of positive electrode precursor]
In the present embodiment, the positive electrode precursor serving as the positive electrode of the non-aqueous lithium storage element can be manufactured by an electrode manufacturing technique in a known lithium ion battery, electric double layer capacitor, or 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-like coating liquid, and this coating liquid is used as the positive electrode A positive electrode precursor can be obtained by coating on one or both sides of the current collector to form a coating film and drying it. You may press the obtained positive electrode precursor, and may adjust the film thickness and bulk density of a positive electrode active material layer. Alternatively, without using a solvent, the positive electrode active material and the lithium compound, and other optional components used as necessary, are mixed in a dry process, and the resulting mixture is press-molded and then conductively bonded. A method of attaching to the positive electrode current collector using an agent is also possible.

  The coating solution for the positive electrode precursor was dry blended with some or all of the various material powders including the positive electrode active material, and then water or an organic solvent and / or a binder or a dispersion stabilizer was dissolved or dispersed therein. You may prepare by adding a liquid or slurry-like substance. A coating solution may be prepared by adding various material powders containing a positive electrode active material to a liquid or slurry substance in which a binder or dispersion stabilizer is dissolved or dispersed in water or an organic solvent. As a method of dry blending, for example, a positive electrode active material and a lithium compound, and a conductive filler as necessary are premixed using a ball mill or the like, and premixing is performed to coat a conductive material on a lithium compound having low conductivity. May be. Thereby, a lithium compound becomes easy to decompose | disassemble with a positive electrode precursor in the lithium dope process mentioned later. When water is used as the solvent of the coating solution, the addition of a lithium compound may make the coating solution alkaline, so a pH adjuster may be added as necessary.

  The dissolution or dispersion method is not particularly limited, but preferably a disperser such as a homodisper, a multi-axis disperser, a planetary mixer, a thin film swirl type high-speed mixer or the like can be used. In order to obtain a coating liquid in a good dispersion state, it is preferable to disperse at a peripheral speed of 1 m / s to 50 m / s. A peripheral speed of 1 m / s or more is preferable because various materials can be dissolved or dispersed satisfactorily. A peripheral speed of 50 m / s or less is preferable because various materials are not easily broken by heat and shearing force due to dispersion, and reaggregation is reduced.

  Regarding the degree of dispersion of the coating liquid, the particle size measured with a particle gauge is preferably 0.1 μm or more and 100 μm or less. As the upper limit of the degree of dispersion, the particle size is more preferably 80 μm or less, and further preferably the particle size is 50 μm or less. A particle size of 0.1 μm or more means that various material powders including the positive electrode active material are not excessively crushed during the preparation of the coating liquid. Further, when the particle size is 100 μm or less, clogging during coating liquid discharge and streaking of the coating film are not generated, and coating can be performed stably.

The viscosity (ηb) of the coating solution for the positive electrode precursor is preferably 1,000 mPa · s to 20,000 mPa · s, more preferably 1,500 mPa · s to 10,000 mPa · s, and even more preferably 1, 700 mPa · s or more and 5,000 mPa · s or less. If the viscosity ((eta) b) of the coating liquid of a positive electrode precursor is 1,000 mPa * s or more, the dripping at the time of coating-film formation will be suppressed and the coating-film width and thickness can be controlled favorably. If the viscosity (ηb) of the coating liquid for the positive electrode precursor is 20,000 mPa · s or less, the pressure loss in the flow path of the coating liquid when using a coating machine can be reduced and the coating can be performed stably. It can be controlled to be less than the thickness of the coating film.
The TI value (thixotropic index value) of the coating solution for the positive electrode precursor is preferably 1.1 or more, more preferably 1.2 or more, and even more preferably 1.5 or more. If the TI value of the coating solution for the positive electrode precursor is 1.1 or more, the coating film width and thickness can be controlled well.

  The method for forming the coating film of the positive electrode precursor is not particularly limited, but preferably a coating machine such as a die coater, a comma coater, a knife coater, or a gravure coating machine can be used. The coating film may be formed by single layer coating or may be formed by multilayer coating. In the case of multilayer coating, the composition of the coating solution may be prepared 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 to 100 m / min, more preferably 0.5 m / min to 70 m / min, and further preferably 1 m / min to 50 m / min. If the coating speed is 0.1 m / min or more, it can be applied stably, and if it is 100 m / min or less, sufficient coating accuracy can be secured.

  The method for drying 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 by changing the temperature in multiple stages. Moreover, you may dry combining several 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. When the drying temperature is 200 ° C. or less, cracking of 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 method for pressing the positive electrode precursor is not particularly limited, but a press such as a hydraulic press or a vacuum press 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, gap, and surface temperature of the press part described later.
The pressing 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. If the pressing pressure is 0.5 kN / cm or more, the electrode strength can be sufficiently increased. When the pressing pressure is 20 kN / cm or less, the positive electrode precursor is unlikely to be bent or wrinkled, and is easily adjusted to a desired film thickness or bulk density of the positive electrode active material layer film.
The gap between the press rolls can be set to an arbitrary value according to the thickness of the positive electrode precursor after drying so as to have a desired thickness and bulk density of the positive electrode active material layer.
The pressing speed can be set to an arbitrary speed so as to reduce the bending and wrinkling of the positive electrode precursor.
The surface temperature of the press part may be room temperature, or the surface of the press part may be heated if necessary. The lower limit of the surface temperature of the press part when heating is preferably the melting point of the binder used minus 60 ° C. or more, more preferably the melting point of the binder minus 45 ° C. or more, and more preferably the melting point of the binder minus 30. It is above ℃. The upper limit of the surface temperature of the press part when heated is preferably the melting point of the binder used plus 50 ° C. or less, more preferably the melting point of the binder plus 30 ° C. or less, more preferably the melting point of the binder plus 20 It is below ℃. For example, when PVdF (polyvinylidene fluoride: melting point 150 ° C.) is used as the binder, it is preferably pressed at 90 ° C. or higher and 200 ° C. or lower, more preferably 105 ° C. or higher and 180 ° C. or lower, and further preferably 120 ° C. or higher and 170 ° C. or lower. Heat the surface of the part. When a styrene-butadiene copolymer (melting point 100 ° C) is used as the binder, it is preferably pressed at 40 ° C to 150 ° C, more preferably 55 ° C to 130 ° C, and even more preferably 70 ° C to 120 ° C. Warm the surface of the part.
The melting point of the binder can be determined at the endothermic peak position of DSC (Differential Scanning Calorimetry). For example, using a differential scanning calorimeter “DSC7” manufactured by PerkinElmer Co., Ltd., 10 mg of sample resin is set in a measurement cell, and the temperature is increased from 30 ° C. to 250 ° C. at a temperature increase 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.
You may press several times, changing conditions of press pressure, a crevice, speed, and surface temperature of a press part.

  The thickness of the positive electrode active material layer is preferably 20 μm or more and 200 μm or less per side of the positive electrode current collector. The thickness of the positive electrode active material layer is more preferably 25 μm or more and 100 μm or less, more preferably 30 μm or more and 80 μm or less per side. If the thickness of the positive electrode active material layer is 20 μm or more, sufficient charge / discharge capacity can be exhibited. When the thickness of the positive electrode active material layer is 200 μm or less, the ion diffusion resistance in the electrode can be kept low. Therefore, if the thickness of the positive electrode current collector layer is 20 μm or more and 200 μm or less, sufficient output characteristics can be obtained, the cell volume can be reduced, and therefore the energy density can be increased. The thickness of the positive electrode active material layer in the case where the positive electrode current collector has through-holes and irregularities is the thickness of the positive electrode active material layer per side in the portion of the positive electrode current collector that does not have through-holes and irregularities. Mean value.

The bulk density of the positive electrode active material layer in the positive electrode after the lithium doping step described later is preferably 0.40 g / cm ³ or more, more preferably 0.50 g / cm ³ or more and 1.3 g / cm ³ or less. When the bulk density of the positive electrode active material layer is 0.40 g / cm ³ or more, a high energy density can be expressed, and miniaturization of the power storage element can be achieved. When the bulk density of the positive electrode active material layer is 1.3 g / cm ³ or less, the electrolyte solution is sufficiently diffused in the pores in the positive electrode active material layer, and high output characteristics are obtained.

<Negative electrode>
The negative electrode in the present embodiment includes a negative electrode current collector and a negative electrode active material layer including a negative electrode active material provided on one or both surfaces thereof.

[Negative electrode active material layer]
The negative electrode active material layer contains a negative electrode active material, and may contain optional components such as a conductive filler, a binder, and a dispersion stabilizer as necessary.

[Negative electrode active material]
As the negative electrode active material, a material capable of inserting and extracting lithium ions can be used. Specific examples of the negative electrode active material include carbon materials, titanium oxide, silicon, silicon oxide, silicon alloys, silicon compounds, tin, and tin compounds. The content of the carbon material is preferably 50% by mass or more, more preferably 70% by mass or more, with respect to the total mass of the negative electrode active material. The content of the carbon material may be 100% by mass, but is preferably 90% by mass or less, for example, 80% by mass or less from the viewpoint of obtaining the effect of the combined use with other materials. Also good.

Examples of carbon materials include non-graphitizable carbon materials; graphitizable carbon materials; carbon blacks; carbon nanoparticles; activated carbon; artificial graphite; natural graphite; graphitized mesophase carbon microspheres; graphite whiskers; Amorphous carbonaceous materials; carbonaceous materials obtained by heat treatment of carbon precursors such as petroleum pitch, coal pitch, mesocarbon microbeads, coke, synthetic resin (eg phenol resin); furfuryl alcohol resin Or, a pyrolysis product of novolak resin; fullerene; carbon nanophone; and a composite carbon material thereof.
Although it does not restrict | limit especially as a carbon material, Activated carbon, carbon black, template porous carbon, high specific surface area graphite, a carbon nanoparticle, etc. can be used suitably.
Among these, from the viewpoint of lowering the resistance of the negative electrode, a pitch composite carbon material that can be obtained by heat treatment in the state where at least one carbon material and a petroleum-based pitch or a coal-based pitch coexist is preferable. Prior to the heat treatment, the carbon material and pitch may be mixed at a temperature higher than the melting point of the pitch. The heat treatment temperature may be a temperature at which a component generated by volatilization or thermal decomposition of the pitch used becomes a carbonaceous material. As the atmosphere for performing the heat treatment, a non-oxidizing atmosphere is preferable.
Preferable examples of the pitch composite carbon material are pitch composite carbon materials 1 and 2 described later. Either of these may be used, or both of these may be used in combination.

In the present specification, the pitch composite carbon material 1 is a mixture of 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 and a petroleum pitch or a coal pitch. It is a material that can be obtained by heat treatment in the state.
In one embodiment, it is preferable that the BET specific surface area of the pitch composite carbon material 1 is 100 m ² / g or more and 1,500 m ² / g or less.
In one embodiment, the doping amount of lithium ions per unit mass of the pitch composite carbon material 1 is preferably 530 mAh / g to 2,500 mAh / g, more preferably 620 mAh / g to 2,100 mAh / g, Preferably they are 760 mAh / g or more and 1,700 mAh / g or less, More preferably, they are 840 mAh / g or more and 1,500 mAh / g or less.
Doping lithium ions lowers the negative electrode potential. Therefore, when a negative electrode including a negative electrode active material doped with lithium ions is combined with a positive electrode, the voltage of the non-aqueous lithium storage element increases and the capacity of the positive electrode increases. Therefore, the capacity and energy density of the obtained non-aqueous lithium storage element are increased.
If the doping amount of lithium ions per unit mass of the pitch composite carbon material 1 is 530 mAh / g or more, the lithium ions in the composite carbon material 1 are well doped into irreversible sites that cannot be desorbed once inserted. Furthermore, the amount of the negative electrode active material with respect to the desired amount of lithium ions can be reduced. Therefore, the negative electrode film thickness can be reduced, and a high energy density can be obtained. The larger the doping amount, the lower the negative electrode potential, and the input / output characteristics, energy density, and durability are improved.
If the doping amount of lithium ions per unit mass of the pitch composite carbon material 1 is 2,500 mAh / g or less, side effects such as precipitation of lithium metal are unlikely to occur.

The pitch composite carbon material 2 is heat-treated in a state where at least one carbon material having a BET specific surface area of 1 m ² / g or more and 30 m ² / g or less and a petroleum-based pitch or a coal-based pitch coexist. It is a material that can be obtained.
In another embodiment, it is also preferable that the BET specific surface area of the pitch composite carbon material 2 is 1 m ² / g or more and 50 m ² / g or less.
In another embodiment, the doping amount of lithium ions per unit mass of the negative electrode active material is preferably 50 mAh / g or more and 700 mAh / g or less, more preferably 70 mAh / g or more and 650 mAh / g or less, and further preferably 90 mAh / g. They are 600 mAh / g or less, More preferably, they are 100 mAh / g or more and 550 mAh / g or less.
If the doping amount of lithium ions per unit mass of the pitch composite carbon material 2 is 50 mAh / g or more, the lithium ions in the composite carbon material 2 are well doped into irreversible sites that cannot be desorbed once inserted. Therefore, a high energy density is obtained. The larger the doping amount, the lower the negative electrode potential, and the input / output characteristics, energy density, and durability are improved.
If the doping amount of lithium ions per unit mass of the pitch composite carbon material 2 is 700 mAh / g or less, side effects such as precipitation of lithium metal hardly occur.
The average particle size of the pitch composite carbon materials 1 and 2 is preferably 1 μm or more and 10 μm or less, the lower limit value is more preferably 2 μm or more, still more preferably 2.5 μm or more, and the upper limit value is more preferably Is 6 μm or less, more preferably 4 μm or less. When the average particle diameter of the negative electrode active material is 1 μm or more and 10 μm or less, good durability is maintained.

(Other components of negative electrode active material layer)
In addition to the negative electrode active material, the negative electrode active material layer in the present embodiment may include optional components such as a conductive filler, a binder, and a dispersion stabilizer as necessary.

  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 more than 0 parts by mass and less than 30 parts by mass, more preferably more than 0 parts by mass and less than 20 parts by mass, and even more preferably more than 0 parts by mass and more than 15 parts by mass with respect to 100 parts by mass of the negative electrode active material. Or less.

  The binder is not particularly limited. 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 2 parts by mass or more and 27 parts by mass or less, and still more preferably 3 parts by mass or more and 25 parts by mass with respect to 100 parts by mass of the negative electrode active material. Or less. When the amount of the binder is 1% by mass or more, sufficient electrode strength is exhibited. When the amount of the binder is 30 parts by mass or less, high input / output characteristics are exhibited without inhibiting lithium ions from entering and leaving the negative electrode active material.

  Although it does not restrict | limit especially as a dispersion stabilizer, For example, PVP (polyvinyl pyrrolidone), PVA (polyvinyl alcohol), a cellulose derivative etc. can be used. The amount of the dispersion stabilizer used is preferably 0 to 10 parts by mass 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 lithium ions from entering and leaving the negative electrode active material.

[Negative electrode current collector]
The material constituting the negative electrode current collector in the present embodiment is preferably a metal foil that has high electron conductivity and is unlikely to deteriorate due to elution into the electrolytic solution and reaction with the electrolyte or ions. There is no restriction | limiting in particular as such metal foil, For example, aluminum foil, copper foil, nickel foil, stainless steel foil, etc. are mentioned. As the negative electrode current collector in the non-aqueous lithium electricity storage device of the present embodiment, a copper foil is preferable.
The metal foil may be a normal metal foil having no irregularities or through holes, or a metal foil having irregularities subjected to embossing, chemical etching, electrolytic deposition, blasting, etc., expanded metal, punching metal, A metal foil having a through-hole 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 for example, 1 to 100 μm is preferable. When the negative electrode current collector has holes or irregularities, the thickness of the negative electrode current collector is measured based on a portion where no holes or irregularities exist.

[Manufacture 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. Typically, the negative electrode active material layer is fixed on one side or both sides of the negative electrode current collector.
The negative electrode can be manufactured by an electrode manufacturing technique in a known lithium ion battery, electric double layer capacitor or 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-like coating liquid, and this coating liquid is applied to one or both surfaces of the negative electrode current collector. A negative electrode can be obtained by forming a coating film and drying it. You may press the obtained negative electrode and adjust the film thickness and bulk density of a negative electrode active material layer. Alternatively, without using a solvent, a method in which various materials including a negative electrode active material are mixed by a dry method, the resulting mixture is press-molded, and then attached to a negative electrode current collector using a conductive adhesive Is also possible.

  The coating liquid is a liquid or slurry in which a part or all of various material powders including the negative electrode active material are dry blended, and then water or an organic solvent and / or a binder or a dispersion stabilizer is dissolved or dispersed therein. It may be prepared by adding these substances. In addition, a coating liquid may be prepared by adding various material powders containing a negative electrode active material to a liquid or slurry substance in which a binder or dispersion stabilizer is dissolved or dispersed in water or an organic solvent. .

  The dissolving or dispersing method is not particularly limited, but preferably a disperser such as a homodisper, a multi-axis disperser, a planetary mixer, a thin film swirl type high speed mixer or the like can be used. In order to obtain a coating liquid in a good dispersion state, it is preferable to disperse at a peripheral speed of 1 m / s to 50 m / s. A peripheral speed of 1 m / s or more is preferable because various materials can be dissolved or dispersed satisfactorily. A peripheral speed of 50 m / s or less is preferable because various materials are not easily broken by heat and shearing force due to dispersion, and reaggregation is reduced.

The viscosity (ηb) of the negative electrode coating solution is preferably 1,000 mPa · s to 20,000 mPa · s, more preferably 1,500 mPa · s to 10,000 mPa · s, and still more preferably 1,700 mPa · s. s to 5,000 mPa · s. When the viscosity (ηb) of the coating liquid for the negative electrode is 1,000 mPa · s or more, dripping at the time of coating film formation is suppressed, and the coating film width and thickness can be controlled well. When the viscosity (ηb) of the negative electrode coating liquid is 20,000 mPa · s or less, there is little pressure loss in the flow path of the coating liquid when a coating machine is used, and the coating can be performed stably. The film thickness can be controlled below.
The TI value (thixotropic index value) of the negative electrode coating solution is preferably 1.1 or more, more preferably 1.2 or more, and further preferably 1.5 or more. If the TI value of the negative electrode coating liquid is 1.1 or more, the coating film width and thickness can be controlled well.

  The method for forming the coating film of the negative electrode is not particularly limited, but preferably a coating machine such as a die coater, a comma coater, a knife coater, or a gravure coating machine can be used. The coating film may be formed by single layer coating or may be formed by multilayer coating. The coating speed is preferably 0.1 m / min to 100 m / min, more preferably 0.5 m / min to 70 m / min, and further preferably 1 m / min to 50 m / min. If the coating speed is 0.1 m / min or more, it can be applied stably, and if it is 100 m / min or less, sufficient coating accuracy can be secured.

  The method for drying the negative electrode 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 by changing the temperature in multiple stages. Moreover, you may dry combining several 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. When the drying temperature is 200 ° C. or lower, it is possible to suppress cracking of 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.

The method for pressing the negative electrode is not particularly limited, but a press such as a hydraulic press or a vacuum press 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, gap, and surface temperature of the press part described later.
The pressing 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. If the pressing pressure is 0.5 kN / cm or more, the electrode strength can be sufficiently increased. When the pressing pressure is 20 kN / cm or less, the negative electrode is unlikely to be bent or wrinkled, and is easily adjusted to a desired film thickness or bulk density of the negative electrode active material layer film.
The gap between the press rolls can be set to an arbitrary value according to the negative electrode film thickness after drying so as to have a desired film thickness and bulk density of the negative electrode active material layer.
The pressing speed can be set to an arbitrary speed so as to reduce the bending and wrinkling of the negative electrode.
The surface temperature of the press part may be room temperature, or the surface of the press part may be heated if necessary. The lower limit of the surface temperature of the press part when heating is preferably the melting point of the binder used minus 60 ° C. or more, more preferably the melting point of the binder minus 45 ° C. or more, and more preferably the melting point of the binder minus 30. It is above ℃. The upper limit of the surface temperature of the press part when heated is preferably the melting point of the binder used plus 50 ° C. or less, more preferably the melting point of the binder plus 30 ° C. or less, more preferably the melting point of the binder plus 20 It is below ℃. For example, when PVdF (polyvinylidene fluoride: melting point 150 ° C.) is used as the binder, it is preferably pressed at 90 ° C. or higher and 200 ° C. or lower, more preferably 105 ° C. or higher and 180 ° C. or lower, and further preferably 120 ° C. or higher and 170 ° C. or lower. Heat the surface of the part. When a styrene-butadiene copolymer (melting point 100 ° C) is used as the binder, it is preferably pressed at 40 ° C to 150 ° C, more preferably 55 ° C to 130 ° C, and even more preferably 70 ° C to 120 ° C. Warm the surface of the part.
The melting point of the binder can be determined at the endothermic peak position of DSC (Differential Scanning Calorimetry). For example, using a differential scanning calorimeter “DSC7” manufactured by PerkinElmer Co., Ltd., 10 mg of sample resin is set in a measurement cell, and the temperature is increased from 30 ° C. to 250 ° C. at a temperature increase 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.
You may press several times, changing conditions of press pressure, a crevice, speed, and surface temperature of a press part.

  The thickness of the negative electrode active material layer is preferably 5 μm or more and 100 μm or less per side of the negative electrode current collector. The lower limit of the thickness of the negative electrode active material layer is more preferably 7 μm or more, and further preferably 10 μm or more. The upper limit of the thickness of the negative electrode active material layer is more preferably 80 μm or less, and even more preferably 60 μm or less. When the thickness of the negative electrode active material layer is 5 μm or more, streaks or the like hardly occur when the negative electrode active material layer is applied, and the coating property is excellent. When the thickness of the negative electrode active material layer is 100 μm or less, a high energy density can be expressed by reducing the cell volume. The thickness of the negative electrode active material layer in the case where the negative electrode current collector has through-holes or irregularities is the thickness of the negative electrode active material layer per side in the portion of the negative electrode current collector that does not have through-holes or irregularities. Mean value.

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 0.45 g. / Cm ³ or more and 1.3 g / cm ³ or less. When the bulk density of the negative electrode active material layer 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. If the bulk density of the negative electrode active material layer is 1.8 g / cm ³ or less, vacancies capable of sufficiently diffusing ions in the negative electrode active material layer can be secured.

The BET specific surface area, mesopore amount, and micropore amount in the present embodiment are values determined by the following methods, respectively. The sample is vacuum-dried at 200 ° C. all day and night, and adsorption and desorption isotherms are measured using nitrogen as an adsorbate. Using the adsorption isotherm obtained here, the BET specific surface area is calculated by the BET multipoint method or the BET single point method, the mesopore amount is calculated by the BJH method, and the micropore amount is calculated by the MP method.
The BJH method is a calculation method generally used for analysis of mesopores, and was proposed by Barrett, Joyner, Halenda et al. (EP Barrett, LG Joyner and P. Halenda, J. Am.Chem.Soc., 73, 373 (1951)).
The MP method uses a “t-plot method” (BC Lippens, JH de Boer, J. Catalysis, 4319 (1965)), and uses a micropore volume, a micropore area, and a micropore. Is a method for obtaining the distribution of R. S. This is a method devised by Mikhal, Brunauer, Bodor (RS Mikhal, S. Brunauer, EE Bodor, J. Colloid Interface Sci., 26, 45 (1968)).

<Separator>
The positive electrode precursor and the negative electrode are generally wound in a flat shape via a separator to form a flat wound electrode body having a positive electrode precursor, a negative electrode, and a separator.
As the separator, a polyethylene microporous film or a polypropylene microporous film used in a lithium ion secondary battery, a cellulose nonwoven paper used in an electric double layer capacitor, or the like can be used. A film composed 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. It is preferable that the thickness of the separator is 5 μm or more because self-discharge due to an internal micro short circuit tends to be small. It is preferable that the thickness of the separator is 35 μm or less because the output characteristics of the power storage element tend to be high.

  The thickness of the film composed of organic or inorganic fine particles is preferably 1 μm or more and 10 μm or less. A film composed of organic or inorganic fine particles having a thickness of 1 μm or more is preferable because self-discharge due to internal micro-shorts tends to be small. It is preferable that the thickness of the film composed of organic or inorganic fine particles is 10 μm or less because the output characteristics of the electricity storage element tend to be high.

<Exterior body>
A metal can, a laminate film, or the like can be used as the exterior body. The metal can is preferably made of aluminum. As the laminate film, a film in which a metal foil and a resin film are laminated is preferable. For example, a laminate film composed of three layers of an outer layer resin film / metal foil / inner layer 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 suitably used. The metal foil is for preventing the permeation of moisture and gas, and foils of copper, aluminum, stainless steel and the like can be suitably used. The inner layer resin film protects the metal foil from the electrolyte contained therein, and melts and seals the outer body during heat sealing. Polyolefin, acid-modified polyolefin, and the like can be suitably used.

<Non-aqueous electrolyte>
The electrolytic solution in the present embodiment is a non-aqueous electrolytic solution containing lithium ions. The non-aqueous electrolyte contains a non-aqueous solvent described later. The non-aqueous electrolyte solution preferably contains 0.5 mol / L or more lithium salt based on the total volume of the non-aqueous electrolyte solution.

The nonaqueous electrolytic solution in the present embodiment is, for example, (LiN (SO ₂ F) ₂ ), LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiN (SO ₂ ) as a lithium salt. _{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 , MC ₄ F ₉ SO ₃ , LiPF ₆ , LiBF _{4 and the} like can be used alone, or two or more kinds may be mixed and used. LiPF ₆ and / or LiN (SO ₂ F) ₂ are preferably included because high conductivity can be exhibited.

  The lithium salt concentration in the non-aqueous electrolyte is preferably 0.5 mol / L or more, and more preferably in the range of 0.5 to 2.0 mol / L. If the lithium salt concentration is 0.5 mol / L or more, anions are sufficiently present, so that the capacity of the energy storage device 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 and preventing the viscosity of the electrolyte from becoming too high, resulting in a decrease in conductivity. And output characteristics are not deteriorated.

  The nonaqueous electrolytic solution in the present embodiment preferably contains a cyclic carbonate and a chain carbonate as a nonaqueous solvent. The nonaqueous electrolytic solution containing a cyclic carbonate and a chain carbonate is advantageous in that a lithium salt having a desired concentration is dissolved and a high lithium ion conductivity is exhibited. Examples of the cyclic carbonate include alkylene carbonate compounds represented by ethylene carbonate, propylene carbonate, butylene carbonate, and the like. The alkylene carbonate compound is typically unsubstituted. Examples of the chain carbonate include dialkyl carbonate compounds represented by dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, dibutyl carbonate and the like. The dialkyl carbonate compound is typically unsubstituted.

  The total content of the cyclic carbonate and the chain carbonate is preferably 50% by mass or more, more preferably 65% by mass or more, preferably 95% by mass or less, more preferably, based on the total mass of the non-aqueous electrolyte solution. 90% by mass or less. When the total content of the cyclic carbonate and the chain carbonate is 50% by mass or more, a lithium salt having a desired concentration can be dissolved, and high lithium ion conductivity can be expressed. When the total concentration of the cyclic carbonate and the chain carbonate is 95% by mass or less, the electrolytic solution can further contain an additive described later.

  The non-aqueous electrolyte solution in the present embodiment may further contain an additive. The additive is not particularly limited, and examples thereof include sultone compounds, cyclic phosphazenes, acyclic fluorine-containing ethers, fluorine-containing cyclic carbonates, cyclic carbonates, cyclic carboxylic acid esters, and cyclic acid anhydrides. They can be used alone or in admixture of two or more.

<Method for producing non-aqueous lithium storage element>
[Assembly process]
In the assembly process of one embodiment, for example, a positive electrode precursor and a negative electrode that are cut into a strip shape are wound into a flat wound body that is wound in a flat shape through a strip-shaped separator, and the positive electrode terminal and the negative electrode terminal are connected, A flat wound electrode body is produced. The flat wound electrode body can be produced by, for example, a method of winding a flat plate around an axis, or a method of rolling a cylindrical core around the axis and then crushing it flatly.

Hereinafter, the flat wound electrode body will be described. In FIG. 1, which is a cross section parallel to the winding direction of the flat wound electrode body included in the exterior body, the projected length of the wide portion is X, and the length of the narrow portion projected in the direction perpendicular to the wide portion is Y. At this time, a flat wound electrode body having X> 1.5Y is used.
In FIG. 1, the layer configuration of the flat wound electrode body (2) included in the exterior body (1) is omitted, but the flat wound electrode body (2) is a single or a plurality of positive electrodes, A plurality of negative electrodes and one or more separators can be included.
In the present embodiment, the positive electrode active material layer of the flat portion (3) is a positive electrode active material layer arranged in the outermost layer of the flat wound electrode body among one or a plurality of positive electrode active material layers, The positive electrode active material layer is opposed to the negative electrode active material layer, and indicates a projected portion having a length of the projection portion of 0.4X from the center of the wide portion, that is, a total of 0.8X, and a curved portion (4) The positive electrode active material layer is a positive electrode active material layer disposed in the outermost layer of the flat wound electrode body (2), the positive electrode active material layer facing the negative electrode active material layer, and a flat portion ( It refers to the area other than 3).

  As shown in FIG. 2, when the outermost layer of the flat wound electrode body is a positive electrode, the positive electrode active material layer facing the negative electrode active material layer (8) via a separator (10) is formed as a flat positive electrode active material layer as desired. (5). As shown in FIG. 3, when the outermost layer of the flat wound electrode body is a negative electrode, the positive electrode active material layer facing the negative electrode active material layer (8) of the negative electrode through a separator (10) is optionally formed as a positive electrode of the flat part. Let it be an active material layer (5).

  The method for connecting the positive electrode terminal and the negative electrode terminal is not particularly limited, but a method such as resistance welding or ultrasonic welding can be used.

  It is preferable to remove the residual solvent by drying the flat wound electrode body to which the terminal is connected. Although a drying method is not limited, it can dry by vacuum drying etc. The residual solvent is preferably 1.5% by mass or less per total mass of the positive electrode active material layer or the negative electrode active material layer. When the residual solvent is more than 1.5% by mass, the solvent remains in the system and the self-discharge characteristics are deteriorated.

  The dried flat wound electrode body is preferably housed in an exterior body typified by a metal can or a laminate film in a dry environment having a dew point of −40 ° C. or lower, and for pouring a non-aqueous electrolyte. It is preferable to seal with leaving only one opening. When the dew point is higher than −40 ° C., moisture adheres to the flat wound electrode body, water remains in the system, and the self-discharge characteristics are deteriorated. Although the sealing method of an exterior body is not specifically limited, Methods, such as heat sealing and impulse sealing, can be used.

[Liquid injection, impregnation, sealing process]
After the assembly process, a non-aqueous electrolyte is injected into the flat wound electrode body housed in the exterior body. It is desirable that further impregnation is performed after the injection, and the positive electrode, the negative electrode, and the separator are sufficiently immersed in the nonaqueous electrolytic solution. In a state in which the electrolyte solution is not immersed in at least a part of the positive electrode, the negative electrode, and the separator, the lithium doping progresses unevenly in the lithium doping step described later, and thus the resistance of the obtained nonaqueous lithium storage element increases. Or the durability is reduced. The impregnation method is not particularly limited. A method of returning to atmospheric pressure again can be used. After impregnation, the flat wound electrode body with the exterior body opened can be sealed by sealing while reducing the pressure.

[Lithium doping process]
In the lithium doping step, a negative electrode active material layer is formed by applying a voltage between the positive electrode precursor and the negative electrode, decomposing the lithium compound in the positive electrode precursor to release lithium ions, and reducing the lithium ions at the negative electrode. It is preferable to pre-dope lithium ions.
In the lithium doping step, a gas such as CO ₂ is generated with the oxidative decomposition of the lithium compound in the positive electrode precursor. Therefore, when applying a voltage, it is preferable to provide a means for releasing the generated gas to the outside of the exterior body. As this means, for example, a method in which a voltage is applied in a state where a part of the exterior body is opened; in a state in which an appropriate gas releasing means such as a gas vent valve or a gas permeable film is previously installed in a part of the exterior body A method of applying a voltage;

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

[Degassing process]
After the aging step, it is preferable to further degas to reliably remove the gas remaining in the electrolytic solution, the positive electrode, and the negative electrode. In a state where gas remains in at least a part of the electrolytic solution, the positive electrode, and the negative electrode, ion conduction is hindered, and thus the resistance of the obtained nonaqueous lithium storage element increases.
The degassing method is not particularly limited. For example, a method in which a flat wound electrode body is installed in a decompression chamber with the exterior body opened, and the inside of the chamber is decompressed using a vacuum pump, etc. is used. Can do. After degassing, the exterior body is sealed by sealing the exterior body, so that a non-aqueous lithium storage element can be manufactured.

<Inhibition of resistance rise in high load charge / discharge cycle>
In the positive electrode disposed in the outermost layer of the flat wound electrode body among one or a plurality of positive electrodes according to the present embodiment, the curve in the positive electrode active material layer facing the negative electrode active material layer through a separator as desired. The amount of the lithium compound in the positive electrode active material layer in part is C _x1 (g / m ² ), and the amount of the lithium compound in the flat positive electrode active material layer in the positive electrode active material layer is C _y1 (g / m ^2). ), C _x1 and C _y1 are each 0.1 or more and 20 or less, and C _y1 / C _x1 is 0.25 or more and 0.95 or less. When C _x1 and C _y1 are each 0.1 or more, fluorine ions generated in a high-load charge / discharge cycle can be captured, so that an increase in resistance can be suppressed. If C _x1 and C _y1 are each 20 or less, the diffusion of the electrolytic solution and ions contained in the positive electrode is improved, so that the output characteristics are improved.

When a high-load charge / discharge cycle is performed on a non-aqueous lithium storage element, heat is generated in proportion to the square of the charge / discharge current value (J = I, the current value is I, and the resistance of the storage element is R, J = I ² R), however, heat is dissipated mainly from the terminal portion and the outer peripheral portion of the power storage element, so that the temperature of the flat portion increases. At this time, excessive decomposition | disassembly of a lithium compound can be suppressed by making the quantity of the lithium compound contained in the flat part of a flat wound electrode body lower than a curved part. When C _y1 / C _x1 is 0.25 or more, an increase in resistance in a high-load charge / discharge cycle can be suppressed. When C _y1 / C _x1 is 0.95 or less, excessive decomposition of the lithium compound in the flat portion of the positive electrode active material layer can be suppressed, and an increase in resistance due to gas generation can be suppressed.

On the other hand, for the positive electrode according to the present embodiment, the amount of the active material contained in the bent portion of the positive electrode active material layer is C _x2 (g / m ² ), and the amount of the active material contained in the flat portion of the positive electrode active material layer. Is C _y2 (g / m ² ), the ratio C _x2 / C _y2 between the two is preferably 0.85 or more and 1.15 or less. In the present embodiment, the ratio C _x2 / C _y2 is opposite to the ratio C _x1 / C _y1 . Therefore, when the ratio C _x2 / C _y2 is 0.85 or more, excessive decomposition of the lithium compound can be suppressed by suppressing an increase in potential of the flat portion of the positive electrode active material layer, and gas generation can be reduced. Can do. Further, when the ratio C _x2 / C _y2 is 1.15 or less, the diffusion of ions in the flat portion of the positive electrode active material layer is improved, so that an increase in resistance in a high-load charge / discharge cycle can be suppressed.

In the present specification, the flat portion of the positive electrode active material layer is a positive electrode active material layer facing the negative electrode active material layer disposed in the outermost layer of the flat wound electrode body, and the curved portion of the positive electrode active material layer is A positive electrode active material layer facing the negative electrode active material layer disposed in the outermost layer of the flat wound electrode body is used. The heat generated by the high load charge / discharge cycle of the non-aqueous lithium storage element is dissipated from the terminal part and the outer peripheral part of the storage element. It is easy to dissipate heat, and the temperature difference from the flat part appears remarkably. Therefore, when the flat part and the curved part existing in the outermost layer of the flat wound electrode body satisfy the above design matters, the high load charge / discharge cycle characteristics of the non-aqueous lithium storage element are improved.
In this technical field, the bent portion may be referred to as an R portion, a bent portion, or a bent portion.
The flat portion and the curved portion of the positive electrode active material layer may be defined as described above with reference to FIG.

  The method of making the amount of the lithium compound in the flat part of the positive electrode active material layer smaller than the curved part is not particularly limited, and for example, heating the flat part of the non-aqueous lithium storage element during lithium doping treatment described later More specifically, a method of promoting the decomposition of the lithium compound in the flat portion of the positive electrode active material layer by heating the flat portion at 35 ° C. or higher and lower than 80 ° C., preferably 40 ° C. or higher and 60 ° C. or lower, A method of reducing the concentration of the lithium compound in the flat part of the positive electrode active material layer when preparing the precursor is exemplified.

<Characteristic evaluation of non-aqueous lithium storage element>
[Capacitance]
In this specification, the capacitance Fa (F) is a value obtained by the following method.
First, constant current charging is performed in a thermostat set to 25 ° C. with a cell corresponding to the nonaqueous lithium storage element until reaching 3.8 V at a current value of 2 C, and then a constant voltage of 3.8 V is applied. Constant voltage charging is performed for a total of 30 minutes. Then, let Q (C) be the capacity when constant current discharge is performed at a current value of 2C up to 2.2V. Using the Q and the voltage change ΔV _x (V) obtained here, the value calculated by the capacitance Fa = Q / ΔV _x = Q / (3.8−2.2) is obtained as the capacitance Fa. (F).
Here, the current discharge rate (also referred to as “C rate”) is the relative ratio of the current during discharge to the discharge capacity. In general, when performing constant current discharge from the upper limit voltage to the lower limit voltage, it takes 1 hour. The current value at which discharge is completed is referred to as 1C. In this specification, when a constant current discharge is performed from an upper limit voltage of 3.8 V to a lower limit voltage of 2.2 V, the current value at which discharge is completed in 1 hour is defined as 1C.

[Internal resistance]
In this specification, the internal resistance Ra (Ω) is a value obtained by the following method:
First, constant-current charging is performed until a non-aqueous lithium battery element reaches 3.8 V at a current value of 20 C in a thermostat set to 25 ° C., and then a constant voltage of 3.8 V is applied. Perform a total of 30 minutes. Subsequently, the sampling interval is set to 0.1 second, and a constant current discharge is performed up to 2.2 V at 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 time of the discharge time of 2 seconds and 4 seconds by linear approximation is Eo, the drop voltage ΔE = 3.8− It is a value calculated from Eo as Ra = ΔE / (20C current value).

[High-load charge / discharge cycle test]
In this specification, the resistance change rate and gas generation amount after a high load charge / discharge cycle test are measured by the following methods.
(Rate of change in resistance after high-load charge / discharge cycles)
First, constant-current charging is performed until the temperature reaches 3.8 V at a current value of 200 C in a thermostatic chamber set to 25 ° C. with a cell corresponding to the non-aqueous lithium storage element, and then to 2.2 V at a current value of 200 C. Constant current discharge is performed until it reaches. This high-load charge / discharge cycle is repeated 60000 times, and the internal resistance Rb after the high-load charge / discharge cycle is measured according to the internal resistance measurement method. Let Rb / Ra be the rate of change in resistance after a high load charge / discharge cycle.

(Gas generation after high-load charge / discharge cycle)
In this specification, the volume of the non-aqueous lithium storage element is measured by the Archimedes method. Although it does not specifically limit as a solvent used for the volume measurement by Archimedes method, It is preferable to use the solvent whose electrical conductivity is 10 microsiemens / cm or less, and when electrolysis does not occur when a non-aqueous lithium electrical storage element is immersed. For example, pure water or a fluorine-based inert liquid is preferably used. In particular, from the viewpoint of having a high specific gravity and excellent electrical insulation, fluorine-based inert liquids such as Fluorinert (trademark registration, 3M Japan Co., Ltd.) FC-40, FC-43 and the like are preferably used. When the volume of the non-aqueous lithium storage element before the high load charge / discharge cycle is Va and the volume of the non-aqueous lithium storage element after the high load charge / discharge cycle is Vb, Vb−Va is the gas after the high load charge / discharge cycle. The generated amount is V.

<Identification method of lithium compound in electrode>
Although the identification method of the lithium compound contained in a positive electrode is not specifically limited, For example, it can identify by the following method. It is preferable to identify a lithium compound by combining a plurality of analysis methods described below.

When measuring SEM-EDX, Raman, and XPS described below, the measurement can be performed after disassembling the nonaqueous lithium storage element in an argon box, taking out the positive electrode, and washing the electrolyte adhering to the positive electrode surface. preferable. Regarding the method for cleaning the positive electrode, it is only necessary to wash away the electrolyte adhering to the surface of the positive electrode. Therefore, carbonate solvents such as dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate can be suitably used. As a cleaning method, for example, the positive electrode is immersed in a diethyl carbonate solvent 50 to 100 times the weight of the positive electrode for 10 minutes or more, and then the solvent is changed and the positive electrode is immersed again. Thereafter, the positive electrode is taken out from diethyl carbonate and vacuum-dried, and then SEM-EDX, Raman spectroscopy, and XPS analysis are performed. The conditions for vacuum drying are such that the residual amount of diethyl carbonate in the positive electrode is 1% by mass or less in the range of temperature: 0 to 200 ° C., pressure: 0 to 20 kPa, and time: 1 to 40 hours. About the residual amount of diethyl carbonate, GC / MS of the water after distilled water washing | cleaning mentioned later and liquid volume adjustment can be measured, and it can quantify based on the analytical curve created beforehand.
In ion chromatography described later, anions can be identified by analyzing the water after washing the positive electrode with distilled water.

If the lithium compound could not be identified by the analysis method, other analysis methods include ⁷ Li-solid NMR, XRD (X-ray diffraction), TOF-SIMS (time-of-flight secondary ion mass spectrometry), AES (Auger electron) The lithium compound can also be identified by using spectroscopy, TPD / MS (heat generation gas mass spectrometry), DSC (differential scanning calorimetry), or the like.

[Scanning electron microscope-energy dispersive X-ray analysis (SEM-EDX)]
The lithium compound and the positive electrode active material can be discriminated by oxygen mapping using a SEM-EDX image of the positive electrode surface measured with an observation magnification of 1000 to 4000 times. As a measurement example of the SEM-EDX image, the acceleration voltage can be 10 kV, the emission current can be 1 μA, the number of measurement pixels can be 256 × 256 pixels, and the number of integration can be 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. With respect to the SEM-EDX image measurement method, it is preferable to adjust the brightness and contrast so that the brightness does not have pixels that reach the maximum brightness, and the average brightness is in the range of 40% to 60%. When the obtained oxygen mapping is binarized on the basis of the average value of brightness, particles containing 50% or more of bright areas in area are defined as lithium compounds.

[Micro Raman spectroscopy]
Lithium carbonate and the positive electrode active material can be distinguished by Raman imaging of carbonate ions on the surface of the positive electrode precursor 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 is 1, and measurement can be performed with a noise filter. For the measured Raman spectrum, a straight baseline is set in the range of 1071 to 1104 cm ^{−1, and} the area is calculated with a positive value from the baseline as the peak of carbonate ions, and the frequency is integrated. The frequency with respect to the carbonate ion peak area approximated by a Gaussian function is subtracted from the frequency distribution of carbonate ions.

[X-ray photoelectric spectroscopy (XPS)]
The binding state of the lithium compound can be determined by analyzing the electronic state 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 element) 50 times (silicon) The energy step 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 the XPS measurement. As the sputtering condition, for example, the surface of the positive electrode can be cleaned under the condition of an acceleration voltage of 1.0 kV and a range of 2 mm × 2 mm for 1 minute (1.25 nm / min in terms of SiO ₂ ).

About the obtained XPS spectrum,
The peak of Li1s binding energy 50-54 eV is LiO ₂ or Li—C bond;
The peak of _{55~60eV LiF, Li 2 CO 3,} Li x PO y F z ( wherein, x, y, and z are an integer from 1 to 6 respectively);
The peak of C1s binding energy of 285 eV is C—C bond, the peak of 286 eV is C—O bond, the peak of 288 eV is COO, the peak of 290 to 292 eV is CO ₃ ²⁻ , C—F bond;
The peak of O1s binding energy 527 to 530 eV is O ²⁻ (Li ₂ O), the peak of 531 to 532 eV is CO, CO ₃ , OH, PO _x (wherein x is an integer of 1 to 4), SiO _x (wherein x is an integer from 1 to 4), the peak at 533 eV is C—O, SiO _x (wherein x is an integer from 1 to 4);
The peak of F1s binding energy of 685 eV is LiF, the peak of 687 eV is C—F bond, Li _x PO _y F _z (wherein x, y and z are each an integer of 1 to 6), PF ₆ ⁻ ;
For the binding energy of P2p, the peak at 133 eV is PO _x (where x is an integer from 1 to 4), the peak at 134 to 136 eV is PF _x (wherein x is an integer from 1 to 6);
Si2p has a bond energy of 99 eV, Si, and a peak of 101 to 107 eV, Si _x O _y (wherein x and y are each an arbitrary integer)
Can be attributed as
When peaks are overlapped in the obtained spectrum, it is preferable to perform peak separation assuming a Gaussian function or a Lorentz function and assign the spectrum. The existing lithium compound can be identified from the measurement result of the obtained electronic state and the result of the ratio of existing elements.

[Ion chromatography]
By washing the positive electrode precursor with distilled water and analyzing the washed water by ion chromatography, the carbonate ions eluted in the water can be identified. As a column to be used, an ion exchange type, an ion exclusion type, or a reverse phase ion pair type can be used. As the detector, an electrical conductivity detector, an ultraviolet-visible absorption detector, an electrochemical detector, or the like can be used. A non-suppressor method using a solution with low conductivity as the eluent can be used. Further, a mass spectrometer or a charged particle detector can be measured in combination with a detector.
The sample retention time is constant for each ion species component if the conditions such as the column and eluent used are determined, and the magnitude of the peak response differs for each ion species, but is proportional to the concentration of the ion species. . It is possible to qualitatively and quantitatively determine the ionic species component by measuring in advance a standard solution having a known concentration in which traceability is ensured.

<Quantitative method of alkali metal element ICP-MS>
The measurement sample is acid-decomposed using a strong acid such as concentrated nitric acid, concentrated hydrochloric acid, aqua regia, etc., and the resulting solution is diluted with pure water so as to have an acid concentration of 2% to 3%. About acid decomposition, it can also decompose by heating and pressurizing suitably. The obtained diluted solution is analyzed by ICP-MS. At this time, it is preferable to add a known amount of element as an internal standard. When the alkali metal element to be measured is equal to or higher than the measurement upper limit concentration, it is preferable to further dilute while maintaining the acid concentration of the diluted solution. With respect to the obtained measurement results, each element can be quantified based on a calibration curve prepared in advance using a standard solution for chemical analysis.

<Calculation of C _x1 , C _y1 , C _x2 , C _y2 >
The basis weight of the positive electrode active material layer and the method for quantifying the lithium compound contained in the positive electrode active material layer are described below. In an argon box, disassemble the non-aqueous lithium storage element whose voltage is adjusted to 2.9 V, take out the flat wound electrode body, cut out the positive electrode arranged in the outermost layer from the flat wound electrode body, and wash it with an organic solvent To do. The organic solvent is not particularly limited as long as the electrolytic solution deposited on the surface of the positive electrode can be removed, and the elution of the lithium compound is suppressed by using an organic solvent having a lithium compound solubility of 2% or less. As such an organic solvent, for example, polar solvents such as methanol, ethanol, acetone, and methyl acetate are preferably used. Although area measurement is positive is not particularly limited, it is preferable from the viewpoint of reducing the variation in measurement is 2 cm ² or more 200 cm ² or less, more preferably 5 cm ² or more 150 cm ² or less. If the positive electrode area is 2 cm ² or more, the reproducibility of the measurement is ensured. If the positive electrode area is 200 cm ² or less, the sample is easy to handle.

In the positive electrode cleaning method, the positive electrode is sufficiently immersed in an ethanol solution 50 to 100 times the weight of the positive electrode for 3 days or more. For example, the container is preferably covered so that ethanol does not volatilize during the immersion. After soaking for 3 days or more, the positive electrode is taken out of ethanol and vacuum dried. The conditions for vacuum drying are such that the residual ethanol in the positive electrode is 1% by mass or less in the range of temperature: 100 to 200 ° C., pressure: 0 to 10 kPa, and time: 5 to 20 hours. About the residual amount of ethanol, GC / MS of the water after the distilled water washing | cleaning mentioned later can be measured, and it can quantify based on the analytical curve created beforehand. About the obtained positive electrode, the positive electrode active material layer on the opposite surface is removed using a spatula, a brush, a brush, or the like so as to leave the positive electrode active material layer disposed in the outermost layer of the flat wound electrode body. The obtained positive electrode, cut out portions corresponding to the flat portion and the curved portion, the portion corresponding to the curved portion as a positive electrode C _x0, the portion corresponding to the flat portion and the positive electrode C _y0. At this time, the area of the curved portion is X _C (m ² ), the area of the flat portion is Y _C (m ² ), the weight of the positive electrode C _x0 is M _0x (g), and the weight of the positive electrode C _y0 is M _0y ( g). Subsequently, the positive electrode C _x0 and the positive electrode C _y0 are sufficiently immersed in distilled water 100 to 150 times their weight for 3 days or more. It is preferable to cover the container so that distilled water does not volatilize during the immersion, and it is preferable to occasionally stir the aqueous solution to promote elution of the lithium compound. After being immersed for 3 days or more, the positive electrode C _x0 and the positive electrode C _y0 are taken out from distilled water and vacuum-dried in the same manner as the above ethanol cleaning. The weights of the positive electrode C _x0 and the positive electrode C _y0 after the vacuum drying are _defined as M _1x (g) and M _1y (g), respectively. Subsequently, for measuring the weight of the current collector of the positive electrode obtained C _x0 and positive C _y0, spatula, brush, it removes the remaining active material layer on the positive electrode C _x0 and positive C _y0 using a brush or the like. Assuming that the weight of the obtained positive electrode current collector is M _2x (g) and M _2y (g), the amount of lithium compound per C _x0 area C _x1 (g / m ² ) and the amount of lithium compound C per C _y0 area C _y1 (g / m ² ) can be calculated by the following equation (1).
C _x1 = (M _0x −M _1x ) / X _C and C _y1 = (M _0y −M _1y ) / Y _C (1)
The basis weight C _x2 (g / m ² ) of the positive electrode active material layer of the positive electrode C _x0 and the basis weight C _y2 (g / m ² ) of the positive electrode active material layer of the positive electrode C _y0 can be calculated by the following equation (2).
C _x2 = (M _1x −M _2x ) / X _C and C _y2 = (M _1y −M _2y ) / Y _C (2)

When a plurality of lithium compounds are included in the positive electrode active material layer; in addition to the lithium compound, M is one or more selected from Na, K, Rb, and Cs in the following formula, and an oxide such as M ₂ O , Hydroxides such as MOH, halides such as MF and MCl, oxalates such as M ₂ (CO ₂ ) ₂ , carboxylic acids such as RCOOM (wherein R is H, an alkyl group, or an aryl group) when containing salts; as well as the positive electrode active material _{layer, BeCO 3, MgCO 3, CaCO} 3, SrCO 3, and alkaline earth metal carbonates selected from BaCO _3, or alkaline earth metal oxides, alkaline earth metal hydrosulfide When oxides, alkaline earth metal halides, alkaline earth metal oxalates, or alkaline earth metal carboxylates are included, the total amount of these is calculated as the amount of lithium compound To do.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and embodiment of this invention is described concretely, this invention is not limited at all by the following example and comparative example.

<Example 1>
<Preparation of positive electrode active material>
[Preparation Example 1a]
The crushed coconut shell carbide was put into a small carbonization furnace and carbonized at 500 ° C. for 3 hours under a nitrogen atmosphere to obtain a carbide. The obtained carbide was put into an activation furnace, steam heated in a preheating furnace was introduced into the activation furnace at 1 kg / h, and the temperature was increased to 900 ° C. over 8 hours for activation. The activated carbide was taken out and cooled in a nitrogen atmosphere to obtain activated activated carbon. The activated carbon thus obtained was washed with water for 10 hours, drained, dried in an electric dryer maintained at 115 ° C. for 10 hours, and then pulverized with a ball mill for 1 hour to obtain activated carbon 1.
It was 4.2 micrometers as a result of measuring the average particle diameter of the activated carbon 1 using the Shimadzu Corporation laser diffraction type particle size distribution measuring apparatus (SALD-2000J). Moreover, the pore distribution of the activated carbon 1 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 volume (V ₁ ) was 0.52 cc / g, the micropore volume (V ₂ ) was 0.88 cc / g, and V ₁ / V ₂ = 0.59. there were.

[Preparation Example 2a]
The phenol resin was placed in a firing furnace, carbonized at 600 ° C. for 2 hours in a nitrogen atmosphere, pulverized with a ball mill, and classified to obtain a carbide having an average particle diameter of 7 μm. The obtained carbide and KOH were mixed at a mass ratio of 1: 5, put into a firing furnace, and activated by heating at 800 ° C. for 1 hour in a nitrogen atmosphere. The activated carbide was taken out, washed with stirring in dilute hydrochloric acid adjusted to a concentration of 2 mol / L for 1 hour, boiled and washed with distilled water until it became stable between pH 5 and 6, and then dried to obtain activated carbon 2.
It was 7.0 micrometers as a result of measuring the average particle diameter of the activated carbon 2 using the Shimadzu Corporation laser diffraction type particle size distribution measuring apparatus (SALD-2000J). Moreover, the pore distribution of the activated carbon 2 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 volume (V ₁ ) was 1.50 cc / g, the micropore volume (V ₂ ) was 2.28 cc / g, and V ₁ / V ₂ = 0.66. there were.

<Production of positive electrode precursor>
A positive electrode precursor was produced using activated carbon 2 as a positive electrode active material.
50.0 parts by mass of activated carbon 2, 38.5 parts by mass of lithium carbonate 1, 3.0 parts by mass of ketjen black, 1.5 parts by mass of PVP (polyvinylpyrrolidone), and 7 parts of PVDF (polyvinylidene fluoride) 0.0 part by mass and NMP (N-methylpyrrolidone) are mixed and dispersed under the condition of a peripheral speed of 17 m / s using a thin film swirl type high speed mixer film mix manufactured by PRIMIX to obtain a coating liquid. It was.
The viscosity (ηb) and TI value of the obtained coating solution were measured using an E-type viscometer TVE-35H manufactured by Toki Sangyo Co., Ltd. As a result, the viscosity (ηb) was 2,650 mPa · s, and the TI value was 4.1. Moreover, the dispersion degree of the obtained coating liquid was measured using the grain gauge made from Yoshimitsu Seiki. As a result, the particle size was 32 μm.
Using a die coater manufactured by Toray Engineering Co., Ltd., the coating liquid was applied on both surfaces of a 15 μm thick aluminum foil at a coating speed of 1 m / s and dried at a drying temperature of 120 ° C. Obtained. The obtained positive electrode precursor 1 was pressed using a roll press machine under conditions of a pressure of 6 kN / cm and a surface temperature of the pressing part of 25 ° C. The total thickness of the pressed positive electrode precursor 1 was measured at any 10 locations of the positive electrode precursor 1 using a thickness gauge Linear Gauge Sensor GS-551 manufactured by Ono Keiki Co., Ltd. The film thickness of the positive electrode active material layer of the positive electrode precursor 1 was determined by subtracting the thickness of the aluminum foil from the average value of the measured total thickness. As a result, the film thickness of the positive electrode active material layer was 59 μm per side.

<Preparation of negative electrode active material Preparation Example 1>
The BET specific surface area and pore distribution of commercially available artificial graphite were measured by the above-described method using a pore distribution measuring apparatus (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics. As a result, the BET specific surface area was 3.1 m ² / g, and the average particle size was 4.8 μm.
300 g of this artificial graphite is placed in a stainless steel mesh basket and placed on a stainless steel bat containing 30 g of a coal-based pitch (softening point: 50 ° C.). ). Artificial graphite and coal-based pitch were heated to 1000 ° C. in a nitrogen atmosphere over 12 hours and held at the same temperature for 5 hours to cause a thermal reaction to obtain a composite porous carbon material 2a. The obtained composite porous carbon material 2a was cooled to 60 ° C. by natural cooling and taken out from the electric furnace.
About the obtained composite porous carbon material 2a, the BET specific surface area and pore distribution were measured by the same method as described above. As a result, the BET specific surface area was 6.1 m ² / g, and the average particle size was 4.9 μm. Moreover, the mass ratio with respect to activated carbon of the carbonaceous material derived from coal pitch in the composite porous carbon material 2a was 2.0%.

<Manufacture of negative electrode>
A negative electrode was produced using the composite porous carbon material 2a as a negative electrode active material.
84 parts by mass of composite porous carbon material 2a, 10 parts by mass of acetylene black, 6 parts by mass of PVdF (polyvinylidene fluoride), and NMP (N-methylpyrrolidone) are mixed, and the mixture is a thin film made by PRIMIX. Using a swirl type high-speed mixer film mix, dispersion was performed under conditions of a peripheral speed of 17 m / s to obtain a coating liquid 1A.
The viscosity (ηb) and TI value of the resulting coating liquid 1A were measured using an E-type viscometer TVE-35H manufactured by Toki Sangyo Co., Ltd. As a result, the viscosity (ηb) was 2,520 mPa · s, and the TI value was 3.8.
Using a die coater manufactured by Toray Engineering Co., Ltd., a coating liquid 1A was applied on both surfaces of an electrolytic copper foil having a thickness of 10 μm at a coating speed of 2 m / s, and dried at a drying temperature of 120 ° C. to obtain negative electrode 1. It was. Using a roll press machine, pressing was performed under conditions of a pressure of 5 kN / cm and a surface temperature of the pressing part of 25 ° C. The total thickness of the pressed negative electrode 1 was measured at any 10 locations of the negative electrode 1 using a thickness gauge Linear Gauge Sensor GS-551 manufactured by Ono Keiki Co., Ltd. Thereafter, the negative electrode active material layer on one surface of the negative electrode 1 was removed, and the thickness was measured again. Then, all the negative electrode active material layers remaining on the negative electrode current collector were removed, and the thickness of the copper foil was measured. From the obtained measurement results, the thickness of the negative electrode active material layer of the negative electrode 1 was determined. As a result, the film thickness of the negative electrode active material layer was 59 μm per side.

<Preparation of electrolyte>
As an organic solvent, a mixed solvent of ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 33: 67 (volume ratio) is used, and the concentration ratio of LiN (SO ₂ F) ₂ and LiPF ₆ is relative to the total electrolyte. The non-aqueous electrolyte solution 1 is obtained by dissolving each electrolyte salt so that the sum of the concentrations of 75:25 (molar ratio) and LiN (SO ₂ F) ₂ and LiPF ₆ is 1.2 mol / L. It was. The concentrations of LiN (SO ₂ F) ₂ and LiPF ₆ in the nonaqueous electrolytic solution 1 were 0.9 mol / L and 0.3 mol / L, respectively.

<Production of non-aqueous lithium storage element>
The positive electrode precursor 1 was cut into a size of 12.0 cm × 210.0 cm (the size of the positive electrode active material layer was 10.0 cm × 210.0 cm, and the positive electrode active material layer was coated on the positive electrode current collector) The negative electrode uncoated portion is 2.0 cm × 210.0 cm), and the negative electrode 1 is cut into a size of 12.1 × 220.0 cm (the size of the negative electrode active material layer is 10.1 cm × 220.cm). 0 cm, the negative electrode uncoated portion where the negative electrode active material layer is not coated on the negative electrode current collector is 2.0 cm × 220.0 cm.), And the cut positive electrode precursor 1 and negative electrode 1 are made of polyethylene A flat wound electrode body was produced by winding in a flat shape through a separator (manufactured by Asahi Kasei Corporation, thickness 10 μm). A positive electrode terminal and a negative electrode terminal were ultrasonically welded to the obtained flat wound electrode body, put into a container formed of an aluminum laminate packaging material, and three sides including the electrode terminal portion were sealed by heat sealing. The obtained flat wound electrode body had a size of X = 82 mm and Y = 10 mm.

About 70 g of non-aqueous electrolyte solution 1 was injected into a flat wound electrode body housed in an aluminum laminate packaging material in a dry air environment at a temperature of 25 ° C. and a dew point of −40 ° C. or less under atmospheric pressure. Subsequently, the aluminum laminate packaging material containing the flat wound electrode body and the non-aqueous electrolyte solution was placed in a vacuum chamber, the pressure was reduced from atmospheric pressure to -87 kPa, then returned to atmospheric pressure, and allowed to stand for 5 minutes. . Then, after reducing the pressure in the chamber from atmospheric pressure to -87 kPa, the process of returning to atmospheric pressure was repeated 4 times, and then allowed to stand for 15 minutes. Further, the packaging material in the chamber was depressurized from atmospheric pressure to -91 kPa, and then returned to atmospheric pressure. Similarly, the process of reducing the pressure and returning to atmospheric pressure was repeated a total of 7 times (reduced pressure from atmospheric pressure to −95, −96, −97, −81, −97, −97, and −97 kPa, respectively). Through the above steps, the flat wound electrode body was impregnated with the non-aqueous electrolyte solution 1.
Thereafter, the flat wound electrode body impregnated with the non-aqueous electrolyte solution 1 is put into a vacuum sealing machine and sealed at 180 ° C. for 10 seconds at a pressure of 0.1 MPa in a state where the pressure is reduced to −95 kPa. The material was sealed.

[Lithium doping process]
The flat wound electrode body obtained after sealing was placed in an argon box having a temperature of 25 ° C., a dew point of −60 ° C., and an oxygen concentration of 1 ppm. The surplus portion of the aluminum laminate packaging material was cut and opened, and the flat portion of the flat wound electrode body on the aluminum laminate was heated to 40 ° C. using a 6 cm × 10 cm film heater. Thereafter, using a power source (P4LT18-0.2) manufactured by Matsusada Precision Co., Ltd., constant current charging was performed until the voltage reached 4.5 V at a current value of 100 mA, and then 4.5 V constant voltage charging was performed 72 times. Initial charging was performed by a technique that continued for a period of time, and the negative electrode was doped with lithium. After completion of lithium doping, the aluminum laminate was sealed using a heat sealing machine (FA-300) manufactured by Fuji Impulse.

[Aging process]
By taking out the flat wound electrode body after lithium doping from the argon box and performing constant current discharge at 25 mA at 100 mA until reaching a voltage of 3.8 V, and then performing 3.8 V constant current discharge for 1 hour. The voltage was adjusted to 3.8V. Subsequently, the flat wound electrode body was stored in a constant temperature bath at 60 ° C. for 48 hours.

[Degassing process]
The flat wound electrode body after aging was partially unsealed in a dry air environment at a temperature of 25 ° C. and a dew point of −40 ° C. Subsequently, the flat wound electrode body is placed in a decompression chamber, and the pressure is reduced from atmospheric pressure to −80 kPa over 3 minutes using a diaphragm pump (manufactured by KNF, N816.3KT.45.18). The process of returning to atmospheric pressure over 3 times was repeated a total of 3 times. After that, the flat wound electrode body is put in a vacuum sealing machine, and after reducing the pressure to -90 kPa, the aluminum laminate packaging material is sealed by sealing at 200 ° C. for 10 seconds with a pressure of 0.1 MPa, and non-aqueous lithium electricity storage An element was produced. Two non-aqueous lithium electricity storage elements were produced by the above process.

<Evaluation of non-aqueous lithium storage element>
[Measurement of capacitance Fa]
About one of the obtained non-aqueous lithium storage elements, a current value of 2C was obtained using a charge / discharge device (5V, 360A) manufactured by Fujitsu Telecom Networks Fukushima Ltd. in a thermostat set at 25 ° C. The constant current charge was performed until it reached 3.8 V at (1.6 A), and then the constant voltage charge applying a constant voltage of 3.8 V was performed for a total of 30 minutes. After that, the capacity when constant current discharge is performed at a current value of 2 C up to 2.2 V (1.6 A) is Q [C], and the electrostatic capacity calculated by F = Q / (3.8−2.2) The capacity Fa was 1748F.

[Measurement of internal resistance Ra]
About the said non-aqueous lithium electrical storage element, it is 3.8V by the electric current value (16A) of 20C using the charging / discharging apparatus (5V, 360A) by Fujitsu Telecom Networks Fukushima Ltd. in the thermostat set to 25 degreeC. The battery was charged with a constant current until it reached, and then a constant voltage charge was applied for applying a constant voltage of 3.8 V for 30 minutes in total. Thereafter, the sampling time was set to 0.1 second, and a constant current discharge was performed up to 2.2 V at a current value of 20 C (16 A) to obtain a discharge curve (time-voltage). In this discharge curve, the voltage at the discharge time = 0 seconds obtained by extrapolating from the voltage values at the time points of the discharge time of 2 seconds and 4 seconds by linear approximation is Eo, and the drop voltage ΔE = 3.8−Eo, and The internal resistance Ra was calculated from R = ΔE / (current value 20 C), and it was 0.58 mΩ.

[High-load charge / discharge cycle test]
About the said non-aqueous lithium electrical storage element, it is 3.8V by the electric current value (160A) of 200C using the charge / discharge device (5V, 360A) made from Fujitsu Telecom Networks Fukushima Ltd. in the thermostat set to 25 degreeC. The charging / discharging process in which constant current charging was performed until the voltage reached 2.9, and then constant current discharging was performed until the voltage reached 2.2 V at a current value of 200 C was repeated 60000 times under the condition of no pause. When the internal resistance Rb was measured after the end of the cycle, it was 0.67 mΩ and Rb / Ra = 1.16. Moreover, when the volume of the non-aqueous lithium storage element before and after the high load charge / discharge cycle was measured by the Archimedes method, the gas generation amount V was 1.5 cc.

[Calculation of C _x1 , C _y1 , C _x2 , C _y2 ]
The remaining non-aqueous lithium storage element obtained was adjusted to a voltage of 2.9 V, disassembled in an argon box with a dew point temperature of −72 ° C., the flat wound electrode body was taken out, and the positive electrode of the outermost layer of the flat wound electrode body Was taken out. Then, according to the above-mentioned method, _Cx1 , _Cy1 , _Cx2 , _Cy2 was computed from Formula (1) and Formula (2).

<Example 2>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, then continuing 4.5 V constant voltage charging for 36 hours, A non-aqueous lithium electricity storage device was produced in the same manner as in Example 1 except that the negative electrode was doped with lithium.

<Example 3>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, and subsequently continuing 4.5 V constant voltage charging for 12 hours, A non-aqueous lithium electricity storage device was produced in the same manner as in Example 1 except that the negative electrode was doped with lithium.

<Example 4>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.6 V at a current value of 100 mA, and then 4.6 V constant voltage charging is continued for 72 hours. A non-aqueous lithium electricity storage device was produced in the same manner as in Example 1 except that the negative electrode was doped with lithium.

<Example 5>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.6 V at a current value of 100 mA, and then 4.6 V constant voltage charging is continued for 36 hours. A non-aqueous lithium storage element was produced in the same manner as in Example 4 except that the negative electrode was doped with lithium.

<Example 6>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, after performing constant current charging until reaching a voltage of 4.6 V at a current value of 100 mA, continuously performing 4.6 V constant voltage charging for 12 hours, A non-aqueous lithium storage element was produced in the same manner as in Example 4 except that the negative electrode was doped with lithium.

<Example 7>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, by performing constant current charging until reaching a voltage of 4.3 V at a current value of 100 mA, and subsequently continuing 4.3 V constant voltage charging for 72 hours, A non-aqueous lithium electricity storage device was produced in the same manner as in Example 1 except that the negative electrode was doped with lithium.

<Example 8>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, by performing constant current charging until reaching a voltage of 4.3 V at a current value of 100 mA, and subsequently continuing 4.3 V constant voltage charging for 36 hours, A non-aqueous lithium storage element was produced in the same manner as in Example 7 except that the negative electrode was doped with lithium.

<Example 9>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, by performing constant current charging until reaching a voltage of 4.3 V at a current value of 100 mA, and subsequently continuing 4.3 V constant voltage charging for 12 hours, A non-aqueous lithium storage element was produced in the same manner as in Example 7 except that the negative electrode was doped with lithium.

<Example 10>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, the same as in Example 1 except that the flat part of the flat wound electrode body on the aluminum laminate was heated to 50 ° C. using a 6 cm × 10 cm film heater. A non-aqueous lithium storage element was produced by the method described above.

<Example 11>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, then continuing 4.5 V constant voltage charging for 36 hours, A non-aqueous lithium electricity storage device was produced in the same manner as in Example 10 except that the negative electrode was doped with lithium.

<Example 12>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, and subsequently continuing 4.5 V constant voltage charging for 12 hours, A non-aqueous lithium electricity storage device was produced in the same manner as in Example 10 except that the negative electrode was doped with lithium.

<Example 13>
Similar to Example 1 except that the flat portion of the flat wound electrode body on the aluminum laminate was heated to 60 ° C. using a 6 cm × 10 cm film heater in the initial charging of the non-aqueous lithium storage element in the lithium doping step. A non-aqueous lithium storage element was produced by the method described above.

<Example 14>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, then continuing 4.5 V constant voltage charging for 36 hours, A non-aqueous lithium storage element was produced in the same manner as in Example 13 except that the negative electrode was doped with lithium.

<Example 15>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, and subsequently continuing 4.5 V constant voltage charging for 12 hours, A non-aqueous lithium storage element was produced in the same manner as in Example 13 except that the negative electrode was doped with lithium.

<Comparative Example 1>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, the flat portion of the flat wound electrode body on the aluminum laminate was not heated, and constant current charging was performed until the voltage reached 4.5 V at a current value of 100 mA. Thereafter, 4.5 V constant voltage charging was continued for 72 hours to produce a non-aqueous lithium storage element in the same manner as in Example 1 except that the negative electrode was doped with lithium.

<Comparative example 2>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, then continuing 4.5 V constant voltage charging for 36 hours, A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 1 except that the negative electrode was doped with lithium.

<Comparative Example 3>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, and subsequently continuing 4.5 V constant voltage charging for 12 hours, A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 1 except that the negative electrode was doped with lithium.

<Comparative Example 4>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, the flat portion of the flat wound electrode body on the aluminum laminate was not heated, and constant current charging was performed until the voltage reached 4.6 V at a current value of 100 mA. Thereafter, 4.6 V constant voltage charging was continued for 72 hours to produce a non-aqueous lithium storage element in the same manner as in Comparative Example 1 except that the negative electrode was doped with lithium.

<Comparative Example 5>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.6 V at a current value of 100 mA, and then 4.6 V constant voltage charging is continued for 36 hours. A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 4 except that the negative electrode was doped with lithium.

<Comparative Example 6>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, after performing constant current charging until reaching a voltage of 4.6 V at a current value of 100 mA, continuously performing 4.6 V constant voltage charging for 12 hours, A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 4 except that the negative electrode was doped with lithium.

<Comparative Example 7>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, the flat portion of the flat wound electrode body on the aluminum laminate was not heated, and constant current charging was performed until the voltage reached 4.3 V at a current value of 100 mA. Subsequently, a non-aqueous lithium electricity storage device was produced in the same manner as in Comparative Example 1 except that the 4.3 V constant voltage charging was continued for 72 hours, except that the negative electrode was doped with lithium.

<Comparative Example 8>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, by performing constant current charging until reaching a voltage of 4.3 V at a current value of 100 mA, and subsequently continuing 4.3 V constant voltage charging for 36 hours, A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 7, except that the negative electrode was doped with lithium.

<Comparative Example 9>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, by performing constant current charging until reaching a voltage of 4.3 V at a current value of 100 mA, and subsequently continuing 4.3 V constant voltage charging for 12 hours, A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 7, except that the negative electrode was doped with lithium.

<Comparative Example 10>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, the same as in Example 1 except that the flat part of the flat wound electrode body on the aluminum laminate was heated to 80 ° C. using a 6 cm × 10 cm film heater. A non-aqueous lithium storage element was produced by the method described above.

<Comparative Example 11>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, then continuing 4.5 V constant voltage charging for 36 hours, A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 10, except that the negative electrode was doped with lithium.

<Comparative Example 12>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, and subsequently continuing 4.5 V constant voltage charging for 12 hours, A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 10, except that the negative electrode was doped with lithium.

<Comparative Example 13>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, the same as in Example 1 except that the flat part of the flat wound electrode body on the aluminum laminate was heated to 85 ° C. using a 6 cm × 10 cm film heater. A non-aqueous lithium storage element was produced by the method described above.

<Comparative example 14>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, then continuing 4.5 V constant voltage charging for 36 hours, A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 13 except that the negative electrode was doped with lithium.

<Comparative Example 15>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, and subsequently continuing 4.5 V constant voltage charging for 12 hours, A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 13 except that the negative electrode was doped with lithium.

  Table 1 shows the evaluation results of the non-aqueous lithium storage elements of Examples 1 to 15 and Comparative Examples 1 to 15.

<Example 16>
<Production of positive electrode precursor>
50.5 parts by mass of activated carbon 1, 40.0 parts by mass of lithium carbonate, 3.0 parts by mass of ketjen black, 1.5 parts by mass of PVP (polyvinylpyrrolidone), and 5. 5 parts of PVDF (polyvinylidene fluoride). A positive electrode precursor 2 was produced in the same manner as in Example 1 except that 0 part by mass and NMP (N-methylpyrrolidone) were mixed.

<Preparation of negative electrode active material Preparation Example 2>
The BET specific surface area and pore distribution of commercially available coconut shell activated carbon were measured by the above-described method using a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics. As a result, the BET specific surface area was 1,790 m ² / g, the mesopore volume (V ₁ ) was 0.199 cc / g, the micropore volume (V ₂ ) was 0.698 cc / g, and V ₁ / V ₂ = 0. 29, and the average pore diameter was 20.1 mm.

  300 g of this coconut shell activated carbon is put in a stainless steel mesh basket, placed on a stainless steel bat containing 540 g of a coal-based pitch (softening point: 50 ° C.), and both are placed in an electric furnace (effective size in the furnace 300 mm × 300 mm × 300 mm). Coconut shell activated carbon and coal-based pitch were heated to 600 ° C. in a nitrogen atmosphere in 8 hours and held at the same temperature for 4 hours to cause a thermal reaction, thereby obtaining a composite porous carbon material 1b. The obtained composite porous carbon material 1b was cooled to 60 ° C. by natural cooling, and then taken out from the electric furnace.

About the obtained composite porous carbon material 1b, the BET specific surface area and pore distribution were measured by the method similar to the above. As a result, the BET specific surface area was 262 m ² / g, the mesopore volume (V _m1 ) was 0.186 cc / g, the micropore volume (V _m2 ) was 0.082 cc / g, and V _m1 / V _m2 = 2.27. there were. In the composite porous carbon material 1b, the mass ratio of the carbonaceous material derived from the coal-based pitch to the activated carbon was 78%.

<Manufacture of negative electrode>
A negative electrode was produced using the composite porous carbon material 1b as a negative electrode active material.
84 parts by mass of composite porous carbon material 1b, 10 parts by mass of acetylene black, 6 parts by mass of PVdF (polyvinylidene fluoride), and NMP (N-methylpyrrolidone) are mixed, and the mixture is a thin film made by PRIMIX. Using a swirl type high-speed mixer film mix, dispersion was performed under the condition of a peripheral speed of 17 m / s to obtain a coating solution. The viscosity (ηb) and TI value of the obtained coating solution were measured using an E-type viscometer TVE-35H manufactured by Toki Sangyo Co., Ltd. As a result, the viscosity (ηb) was 2,789 mPa · s, and the TI value was 4.3. Using a die coater manufactured by Toray Engineering Co., Ltd., the coating solution was applied to both surfaces of an electrolytic copper foil having a thickness of 10 μm at a coating speed of 2 m / s and dried at a drying temperature of 120 ° C. Obtained. The obtained negative electrode 2 was pressed using a roll press machine under conditions of a pressure of 5 kN / cm and a surface temperature of the pressing part of 25 ° C. The total thickness of the pressed negative electrode 2 was measured at any 10 locations on the negative electrode 2 using a thickness gauge Linear Gauge Sensor GS-551 manufactured by Ono Keiki Co., Ltd. The film thickness of the negative electrode active material layer of the negative electrode 2 was determined by subtracting the thickness of the copper foil from the average value of the measured total thickness. As a result, the film thickness of the negative electrode active material layer was 40 μm per side.

[Measurement of capacity per unit weight of negative electrode]
One piece of the obtained negative electrode 2 was cut into a size of 1.4 cm × 2.0 cm (2.8 cm ² ), and one layer of the negative electrode active material layer applied on both sides of the copper foil was spatula, brush, or The working electrode was removed by using a brush. LiPF ₆ was dissolved at a concentration of 1.0 mol / L in a 1: 1 mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) as an electrolytic solution using metallic lithium as a counter electrode and a reference electrode, respectively. An electrochemical cell was made in an argon box using a non-aqueous solution.
About the obtained electrochemical cell, initial charge capacity was measured in the following procedures using the Toyo System company charge / discharge device (TOSCAT-3100U).
Against the electrochemical cell, at a temperature 25 ° C., after the voltage value at a current value 0.5 mA / cm ² was subjected to constant current charging until 0.01 V, further the current value reached 0.01 mA / cm ² Until constant voltage charging. When the charge capacity at the time of constant current charge and constant voltage charge was evaluated as the initial charge capacity, it was 1.6 mAh, and the capacity per unit mass of the negative electrode 2 (lithium ion dope amount) was 1460 mAh / g. .

<Production and evaluation of non-aqueous lithium storage element>
A non-aqueous lithium storage element was produced and evaluated in the same manner as in Example 1 except that the positive electrode precursor 2 and the negative electrode 2 were used.

<Example 17>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, then continuing 4.5 V constant voltage charging for 36 hours, A non-aqueous lithium storage element was produced in the same manner as in Example 16 except that the negative electrode was doped with lithium.

<Example 18>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, and subsequently continuing 4.5 V constant voltage charging for 12 hours, A non-aqueous lithium storage element was produced in the same manner as in Example 16 except that the negative electrode was doped with lithium.

<Comparative Example 16>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, the flat portion of the flat wound electrode body on the aluminum laminate was not heated, and constant current charging was performed until the voltage reached 4.5 V at a current value of 100 mA. Thereafter, 4.5 V constant voltage charging was continued for 72 hours to produce a non-aqueous lithium electricity storage device in the same manner as in Example 16 except that the negative electrode was doped with lithium.

<Comparative Example 17>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, then continuing 4.5 V constant voltage charging for 36 hours, A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 16 except that the negative electrode was doped with lithium.

<Comparative Example 18>
In the initial charging of the non-aqueous lithium storage element in the lithium doping step, by performing constant current charging until reaching a voltage of 4.5 V at a current value of 100 mA, and subsequently continuing 4.5 V constant voltage charging for 12 hours, A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 16 except that the negative electrode was doped with lithium.

<Example 19>
A non-aqueous lithium storage element was produced in the same manner as in Example 16 except that lithium oxide was used as the lithium compound.

<Example 20>
A non-aqueous lithium storage element was produced in the same manner as in Example 16 except that lithium hydroxide was used as the lithium compound.

<Comparative Example 19>
A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 16 except that lithium oxide was used as the lithium compound.

<Comparative Example 20>
A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 16 except that lithium hydroxide was used as the lithium compound.

  Table 2 shows the evaluation results of the non-aqueous lithium electricity storage devices of Examples 16 to 20 and Comparative Examples 16 to 20.

From Tables 1 and 2, C _y1 / C _x1 is 0.95 or less, that is, the amount of the lithium compound in the flat part is less than that in the curved part, thereby suppressing the decomposition of the lithium compound in the flat part in the high load charge / discharge cycle. It is thought that the resistance increase and gas generation could be suppressed. If the flat part is heated too much to 80 ° C. or more, the lithium compound in the flat part decreases, and if C _y1 / C _x1 becomes less than 0.25, the concentration of fluorine ions generated in a high load charge / discharge cycle increases. It is thought that resistance will rise.

The non-aqueous lithium storage element of the present invention can be suitably used as a storage element in, for example, an instantaneous power peak assist application in a hybrid drive system of an automobile.
The non-aqueous lithium electricity storage device of the present invention is preferable because the effects of the present invention are maximized when applied as, for example, a lithium ion capacitor or a lithium ion secondary battery.

DESCRIPTION OF SYMBOLS 1 Exterior body 2 Flat wound electrode body 3 Flat part 4 Bending part 5 Flat part of the positive electrode active material layer of the outermost layer of a flat wound electrode body 6 Positive electrode collector 7 Positive electrode active material layer 8 Negative electrode active material layer 9 Negative electrode collection Electric body 10 Separator

Claims (10)

A flat winding comprising at least one positive electrode containing a lithium compound other than the active material, at least one negative electrode, and at least one separator, and winding the positive electrode and the negative electrode in a flat shape through the separator. An electrode body; and a non-aqueous electrolyte containing lithium ions;
A non-aqueous lithium storage element comprising:
On the positive electrode current collector of the positive electrode, at least one positive electrode active material layer composed of the active material and the lithium compound is applied,
On the negative electrode current collector of the negative electrode, at least one negative electrode active material layer made of a negative electrode active material capable of inserting and extracting lithium ions is applied, and among the positive electrodes, the flat wound electrode body In the positive electrode disposed in the outermost layer, the amount of the lithium compound in the curved portion of the positive electrode active material layer facing the negative electrode active material layer is C _x1 (g / m ² ), and the positive electrode active material layer When the amount of the lithium compound in the flat portion is C _y1 (g / m ² ), C _x1 and C _y1 are 0.1 or more and 20 or less, respectively, and C _y1 / C _x1 is 0.25 or more and _0.00 . 95 or less,
The non-aqueous lithium storage element. When the basis weight of the positive electrode active material layer in the curved portion is C _x2 (g / m ² ) and the basis weight of the positive electrode active material layer in the flat portion is C _y2 (g / m ² ), C _x2 / C The non-aqueous lithium storage element according to claim 1, wherein _y2 is 0.85 or more and 1.15 or less.   The non-aqueous lithium storage element according to claim 1, wherein the lithium compound is lithium carbonate, lithium oxide, or lithium hydroxide. The positive electrode active material contained in the positive active material layer provided on one surface or on both surfaces of a positive electrode current collector, V ₁ mesopores amount derived from the pores below the calculated diameter 20Å or 500Å where the BJH method (Cc / g), where V < ₂ (cc / g) is the amount of micropores derived from pores having a diameter of less than 20 mm calculated by the MP method, 0.3 <V ₁ ≦ 0.8 and 0.5 met ≦ _{V 2} ≦ 1.0, and specific surface area measured by BET method is activated carbon having the following 1,500 m ² / g or more 3,000 m ² / g, either of the preceding claims 1 The non-aqueous lithium storage element according to item. The positive electrode active material contained in the positive electrode active material layer has a mesopore amount V ₁ (cc / g) derived from pores having a diameter of 20 to 500 mm calculated by BJH method of 0.8 <V ₁ ≦ 2.5. The ratio of micropores V ₂ (cc / g) derived from pores having a diameter of less than 20 mm calculated by the MP method satisfying 0.8 <V ₂ ≦ 3.0 and measured by the BET method The non-aqueous lithium storage element according to any one of claims 1 to 3, which is activated carbon having a surface area of 2,300 m ² / g or more and 4,000 m ² / g or less.   The non-aqueous lithium according to any one of claims 1 to 5, wherein a doping amount of the lithium ion with respect to the negative electrode active material is 530 mAh / g or more and 2,500 mAh / g or less per unit mass of the negative electrode active material. Power storage element. The non-aqueous lithium storage element according to claim 6, wherein the negative electrode active material has a BET specific surface area of 100 m ² / g or more and 1,500 m ² / g or less.   The non-aqueous lithium storage element according to any one of claims 1 to 5, wherein a doping amount of the lithium ions with respect to the negative electrode active material is 50 mAh / g or more and 700 mAh / g or less per unit mass of the negative electrode active material. . The non-aqueous lithium storage element according to claim 8, wherein the negative electrode active material has a BET specific surface area of 1 m ² / g or more and 50 m ² / g or less.   The non-aqueous lithium storage element according to claim 1, wherein an average particle diameter of the negative electrode active material is 1 μm or more and 10 μm or less.

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