WO2015046126A1

WO2015046126A1 - Porous layer for nonaqueous batteries, separator for nonaqueous batteries, electrode for nonaqueous batteries, and nonaqueous battery

Info

Publication number: WO2015046126A1
Application number: PCT/JP2014/075033
Authority: WO
Inventors: 松本　修明; 正也船橋; 祐介高取; 壽夫神崎
Original assignee: 日立マクセル株式会社
Priority date: 2013-09-26
Filing date: 2014-09-22
Publication date: 2015-04-02
Also published as: JPWO2015046126A1

Abstract

Provided are: a highly safe nonaqueous battery; and a porous layer, a separator and an electrode for constituting the nonaqueous battery. A porous layer for nonaqueous batteries according to the present invention contains fine particles having an upper temperature limit of 150°C or more and a copolymer of an N-vinyl carboxylic acid amide of a specific structure and an unsaturated carboxylic acid monomer of a specific structure, said copolymer serving as an organic binder. The copolymerization ratio of the N-vinyl carboxylic acid amide to the unsaturated carboxylic acid monomer in the copolymer is from 50:50 to 95:5 in terms of mass ratio. A separator for nonaqueous batteries according to the present invention is obtained by forming this porous layer on a porous resin film. An electrode for nonaqueous batteries according to the present invention is obtained by forming this porous layer on an electrode mixture layer. A nonaqueous battery according to the present invention is obtained by employing this separator as the separator thereof, or by employing this electrode as the positive electrode and/or the negative electrode thereof.

Description

Nonaqueous battery porous layer, nonaqueous battery separator, nonaqueous battery electrode and nonaqueous battery

The present invention relates to a non-aqueous battery having high safety and a porous layer, a separator and an electrode for constituting the non-aqueous battery.

A lithium secondary battery, which is a type of non-aqueous battery, is widely used as a power source for portable devices such as mobile phones and notebook personal computers because of its high energy density. As the performance of portable devices increases, the capacity of lithium secondary batteries tends to increase further, and it is important to ensure safety.

In current lithium secondary batteries, a polyolefin-based porous film having a thickness of, for example, about 15 to 30 μm is used as a separator interposed between a positive electrode and a negative electrode. In addition, as separator material, the constituent resin of the separator is melted below the thermal runaway temperature of the battery to close the pores, thereby increasing the internal resistance of the battery and improving the safety of the battery in the event of a short circuit. In order to ensure the so-called shutdown effect, polyethylene having a low melting point may be applied.

By the way, as such a separator, for example, a uniaxially stretched film or a biaxially stretched film is used for increasing the porosity and improving the strength. Since such a separator is supplied as a single film, a certain strength is required in terms of workability and the like, and this is secured by the stretching. However, with such a stretched film, the degree of crystallinity has increased, and the shutdown temperature has increased to a temperature close to the thermal runaway temperature of the battery. Therefore, it can be said that the margin for ensuring the safety of the battery is sufficient. hard.

In addition, the film is distorted by the stretching, and when it is exposed to high temperature, there is a problem that shrinkage occurs due to residual stress. The shrinkage temperature is very close to the shutdown temperature. For this reason, when a polyolefin-based porous film separator is used, when the battery temperature reaches the shutdown temperature in the case of abnormal charging, the current must be immediately decreased to prevent the battery temperature from rising. This is because if the pores are not sufficiently closed and the current cannot be reduced immediately, the battery temperature easily rises to the contraction temperature of the separator, and there is a risk of ignition due to an internal short circuit.

As a technique for preventing such a short circuit due to thermal contraction of the separator and improving the reliability of the battery, for example,

Patent Documents

1 and 2 include a technique for improving heat resistance on the surface of a porous resin film containing a thermoplastic resin. It has been proposed to use a separator having a heat-resistant porous layer.

According to the techniques disclosed in

Patent Documents

1 and 2, it is possible to provide a nonaqueous electrolyte battery that is less likely to cause thermal runaway even when abnormally overheated, and that is excellent in safety and reliability.

Patent Document 3 discloses that a specific amount of N-vinylacetamide polymer or water-soluble cellulose derivative and a specific amount as a binder for binding the heat-resistant fine particles as the main component in the heat-resistant porous layer. The separator which can improve the reliability of the battery further compared with the separator of patent document 1 and patent document 2 by using together with the crosslinked acrylic resin of this is disclosed.

JP 2008-123996 A JP 2008-210791 A International Publication No. 2010/104127

However, it has been clarified by the present inventors that the polymer of N-vinylacetamide has room for improvement with respect to the resistance to the non-aqueous electrolyte in a high temperature environment.

This invention is made | formed in view of the said situation, The objective is providing the non-aqueous battery which has high safety | security, the porous layer, separator, and electrode for comprising the said non-aqueous battery. It is in.

The porous layer for a nonaqueous battery of the present invention that has achieved the above object is a porous layer for a nonaqueous battery containing fine particles having an allowable temperature limit of 150 ° C. or more and an organic binder, and the organic binder includes: A copolymer of an N-vinylcarboxylic acid amide represented by the general formula (1) and an unsaturated carboxylic acid monomer represented by the following general formula (2), the N-vinylcarboxylic acid in the copolymer: The copolymerization ratio of the acid amide and the unsaturated carboxylic acid monomer is 50:50 to 95: 5 by mass ratio.

In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, and R ³ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.

In the general formula (2), R ⁴ represents a hydrogen atom, a methyl group or —COOM ² , R ⁵ represents a hydrogen atom, a methyl group or —COOM ³ , and M ¹ , M ² and M ³ each independently represent hydrogen. An atom, an alkali metal, an alkaline earth metal, an ammonium group or an organic amino group is represented, and n is 0 or 1.

The separator for nonaqueous batteries of the present invention is characterized in that the porous layer for nonaqueous batteries of the present invention is formed on a porous resin film.

Furthermore, the electrode for nonaqueous battery of the present invention is characterized in that a porous layer for nonaqueous battery is formed on an electrode mixture layer.

The nonaqueous battery of the present invention includes (a) a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte, and the separator is the nonaqueous battery separator of the present invention, or (b) a positive electrode, a negative electrode And at least one of the positive electrode and the negative electrode is a nonaqueous battery electrode of the present invention.

In the present specification, “heat-resistant temperature is 150 ° C. or higher” means that deformation such as softening is not observed at least at 150 ° C.

According to the present invention, it is possible to provide a non-aqueous battery having high safety, and a porous layer, a separator, and an electrode for constituting the non-aqueous battery.

It is a longitudinal section showing an example of the nonaqueous battery of the present invention typically.

The porous layer for non-aqueous batteries of the present invention (hereinafter sometimes simply referred to as “porous layer”) is used as a separator for separating the positive electrode and the negative electrode in the non-aqueous battery, and has a heat resistant temperature. It contains fine particles of 150 ° C. or higher and an organic binder, and the fine particles are bound together by the organic binder.

By forming the porous layer of the present invention on the porous resin film, the separator for a non-aqueous battery of the present invention can be constituted, and on the electrode mixture layer of the electrode (positive electrode or negative electrode) of the non-aqueous battery. Thus, the nonaqueous battery electrode of the present invention can be configured. In the separator for a non-aqueous battery of the present invention, the organic binder binds the constituent components (such as fine particles having a heat resistant temperature of 150 ° C. or higher) in the porous layer, and the porous layer and the porous resin film. And are adhered. In the electrode for a non-aqueous battery of the present invention, the organic binder binds the constituent components (such as fine particles having a heat resistant temperature of 150 ° C. or higher) in the porous layer, and the porous layer and the electrode. The electrode mixture layer is adhered.

In the porous layer of the present invention, as an organic binder, a copolymer of N-vinylcarboxylic acid amide represented by the general formula (1) and an unsaturated carboxylic acid monomer represented by the general formula (2) The copolymerization ratio of the N-vinylcarboxylic amide and the unsaturated carboxylic acid monomer is 50:50 to 95: 5 by mass.

A polymer having N-vinylcarboxylic acid amide represented by the general formula (1) as a monomer, such as poly N-vinylacetamide, may be used in a nonaqueous electrolysis that is employed in a normal nonaqueous battery depending on its composition. When exposed to a high temperature of 100 ° C. or higher in a liquid (non-aqueous electrolyte solvent), the adhesiveness may decrease. In a porous layer using this as a binder, for example, the binding state of components May not be maintained satisfactorily, and the assumed characteristics (mainly heat resistance) may not be sufficiently ensured.

The present inventors have obtained a structural part derived from the N-vinylcarboxylic acid amide represented by the general formula (1) and a structural part derived from the unsaturated carboxylic acid monomer represented by the general formula (2). It has been found that a copolymer containing a specific ratio can increase resistance to a high-temperature non-aqueous electrolyte compared to poly N-vinylacetamide and the like, and based on this finding, the copolymer is made porous. By using it as an organic binder for the layer, it was found that higher safety (safety at a high temperature such as 100 ° C. or higher) than before can be imparted to the nonaqueous battery, and the present invention has been completed.

Examples of the N-vinylcarboxylic amide represented by the general formula (1) include N-vinylformamide, N-vinylacetamide, N-methyl-N-vinylformamide, N-methyl-N-vinylacetamide and the like. Among them, one or more of them can be used for the synthesis of the copolymer. Of these, N-vinylacetamide is particularly preferred.

Examples of the unsaturated carboxylic acid monomer represented by the general formula (2) include acrylic acid, methacrylic acid, acrylates (alkali metal salts such as sodium salts and potassium salts), methacrylates ( Sodium salts, alkali salts such as potassium salts, etc.) are preferred, and one or more of them can be used for the synthesis of the copolymer. Among these, alkali metal salts of acrylic acid and alkali metal salts of methacrylic acid are particularly preferable.

In the copolymer of the N-vinylcarboxylic acid amide represented by the general formula (1) and the unsaturated carboxylic acid monomer represented by the general formula (2), the copolymer composition is the above N-vinyl. When the total of the carboxylic acid amide and the unsaturated carboxylic acid monomer is 100% by mass, the ratio of the unsaturated carboxylic acid monomer is 5% by mass or more, preferably 7% by mass or more, More preferably, it is 10% by mass or more (that is, the proportion of the N-vinylcarboxylic amide is 95% by mass or less, preferably 93% by mass or less, and more preferably 90% by mass or less. preferable). With a copolymer having such a copolymer composition, resistance in a high-temperature non-aqueous electrolyte solvent is improved, and its adhesive strength is less likely to be impaired. A porous layer capable of constituting a battery can be formed.

However, the copolymer of the N-vinylcarboxylic acid amide represented by the general formula (1) and the unsaturated carboxylic acid monomer represented by the general formula (2) is derived from the unsaturated carboxylic acid monomer. If the amount of the component is too large, the hygroscopicity of the copolymer may increase, and the battery characteristics of the nonaqueous battery using the porous layer may be impaired. In addition to the polymer, a composition containing fine particles or a solvent having a heat resistant temperature of 150 ° C. or higher (details will be described later)) may increase the viscosity too much, thereby impairing the coatability. Therefore, in the copolymer of the N-vinylcarboxylic amide represented by the general formula (1) and the unsaturated carboxylic acid monomer represented by the general formula (2), the copolymer composition is When the total of N-vinylcarboxylic acid amide and the unsaturated carboxylic acid monomer is 100% by mass, the ratio of the unsaturated carboxylic acid monomer is 50% by mass or less and 30% by mass or less. (Ie, the proportion of the N-vinylcarboxylic acid amide is 50% by mass or more, and preferably 70% by mass or more).

The molecular weight of the copolymer of the N-vinylcarboxylic acid amide represented by the general formula (1) and the unsaturated carboxylic acid monomer represented by the general formula (2) was determined using gel permeation chromatography. The number average molecular weight (polystyrene equivalent value) measured is preferably 30,000 or more, more preferably 50,000 or more, preferably 5,000,000 or less, more preferably 3,000,000 or less. More preferably, it is 2,000,000 or less.

A copolymer having a ratio of the N-vinylcarboxylic acid amide represented by the general formula (1) and the unsaturated carboxylic acid monomer represented by the general formula (2) within the above range is used as the organic binder. As a result, it is possible to reduce the amount of moisture brought into the battery as the binder absorbs moisture, compared to the case where an organic binder is used as the copolymer in which the unsaturated carboxylic acid monomer is too much. In the non-aqueous battery separator of the present invention in which the non-aqueous battery porous layer of the present invention containing the organic binder is formed on a porous resin film, the water content of the separator as a whole is 1500 ppm or less. Is preferred.

The moisture content of the separator referred to in this specification can be measured by the following method. A separator sample for measurement is allowed to stand in a glove box having a dew point of −50 ° C. for 12 hours or more, and then the measurement sample is placed in a heating furnace at 150 ° C. in which nitrogen gas is flowed and held for 1 minute. Then, the flowd nitrogen gas is introduced into the measurement cell of the Karl Fischer moisture meter, and the moisture content is measured. The integrated value up to the titration end point is taken as the moisture content. The measurement is performed in a glove box having a dew point of −50 ° C., and the water content per unit mass of the separator (unit: ppm) is calculated by dividing the measured value by the mass of the sample.

The copolymer of the N-vinylcarboxylic amide represented by the general formula (1) and the unsaturated carboxylic acid monomer represented by the general formula (2) is ethylene, propylene, vinyl alcohol, acetic acid. It can further include other ethylenically unsaturated monomer components such as vinyl, acrylonitrile, or derivatives thereof. However, in order not to inhibit the above action, the ratio is desirably 20% by mass or less of the entire copolymer.

In the porous layer of the present invention, as an organic binder, a copolymer of an N-vinylcarboxylic acid amide represented by the general formula (1) and an unsaturated carboxylic acid monomer represented by the general formula (2) is used. Although only a combination may be used, other organic binders may be used together with the copolymer. Examples of such other organic binders include ethylene-vinyl acetate copolymers (EVA, those having a structural unit derived from vinyl acetate of 20 to 35 mol%), (meth) acrylate polymers [“(meth) acrylates”. "Means including acrylate and methacrylate. ], Fluorinated rubber, styrene butadiene rubber (SBR), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyvinyl pyrrolidone (PVP), polyurethane, poly N-vinylacetamide (N-vinylacetamide homopolymer), etc. And one or more of these can be used.

Of the total organic binder in the porous layer, a copolymer of N-vinylcarboxylic acid amide represented by the general formula (1) and an unsaturated carboxylic acid monomer represented by the general formula (2) The content of the organic binder other than is preferably 10% by mass or less.

The fine particles having a heat-resistant temperature of 150 ° C. or more are short-circuited due to lithium dendrite by becoming a main component in the porous layer of the present invention or filling voids formed between fibrous materials described later. Has the effect of suppressing the occurrence. The fine particles having a heat-resistant temperature of 150 ° C. or higher have electrical insulating properties, are electrochemically stable, and further contain a non-aqueous electrolyte and porous layer forming composition (composition containing a solvent) described later. There is no particular limitation as long as it is stable to the solvent used in the above and is stable at high temperatures and has high heat resistance.

As used herein, “stable to non-aqueous electrolyte” means deformation and chemical composition change in non-aqueous electrolyte (non-aqueous electrolyte used as non-aqueous battery electrolyte). It means not. The “high temperature state” in the present specification is specifically a temperature of 150 ° C. or higher, and is a stable particle that does not undergo deformation or chemical composition change in a non-aqueous electrolyte at such a temperature. I just need it. Further, “electrochemically stable” as used in the present specification means that no chemical change occurs during charging / discharging of the battery.

Specific examples of such fine particles having a heat resistant temperature of 150 ° C. or higher include, for example, oxide fine particles such as iron oxide, SiO ₂ , Al ₂ O ₃ , TiO ₂ , BaTiO ₃ , ZrO ₂ , MgO; aluminum nitride, Nitride fine particles such as silicon nitride; poorly soluble ionic crystal fine particles such as calcium fluoride, barium fluoride and barium sulfate; covalently bonded crystal fine particles such as silicon and diamond; clay fine particles such as talc and montmorillonite; boehmite, zeolite, Examples thereof include inorganic fine particles such as substances derived from mineral resources such as apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, hydrotalcite, or artificial products thereof. Further, the surface of conductive fine particles such as metal fine particles; oxide fine particles such as SnO ₂ and tin-indium oxide (ITO); carbonaceous fine particles such as carbon black and graphite; Fine particles imparted with electrical insulation properties may be obtained by surface treatment with the above-mentioned materials that constitute fine particles having an electrical insulating heat-resistant temperature of 150 ° C. or higher.

Also, organic fine particles can be used for the fine particles having a heat resistant temperature of 150 ° C. or higher. Specific examples of organic fine particles include polyimide, melamine resin, phenolic resin, crosslinked polymethyl methacrylate (crosslinked PMMA), crosslinked polystyrene (crosslinked PS), polydivinylbenzene (PDVB), benzoguanamine-formaldehyde condensate, etc. Molecular fine particles; heat-resistant polymer fine particles such as thermoplastic polyimide; The organic resin (polymer) constituting these organic fine particles is a mixture, modified body, derivative, copolymer (random copolymer, alternating copolymer, block copolymer, graft copolymer) of the materials exemplified above. ) Or a crosslinked product (in the case of the heat-resistant polymer).

These fine particles having a heat-resistant temperature of 150 ° C. or higher may be used alone or in combination of two or more. Among these, oxide or hydroxide fine particles such as SiO ₂ , Al ₂ O ₃ and boehmite are particularly preferable.

The form of the fine particles having a heat resistant temperature of 150 ° C. or higher may be any form such as a spherical shape, a particle shape, or a plate shape, but a plate shape is preferable. Examples of the plate-like particles include various commercially available products. For example, “Sun Lovely” (SiO ₂ ) manufactured by Asahi Glass Stech Co., Ltd., “NST-B1” pulverized product (TiO ₂ ) manufactured by Ishihara Sangyo Co., Ltd., Sakai Chemical Industry Co., Ltd. Plate-like barium sulfate “H series”, “HL series”, Hayashi Kasei “micron white” (talc), Hayashi Kasei “bengel” (bentonite), Kawai lime “BMM” and “BMT” (Boehmite), “Cerasur BMT-B” [Alumina (Al ₂ O ₃ )] manufactured by Kawai Lime Co., Ltd., “Seraph” (Alumina) manufactured by Kinsei Matec Co., Ltd. ) Etc. are available. In addition, SiO ₂ , Al ₂ O ₃ , ZrO ₂ , and CeO ₂ can be produced by the method disclosed in Japanese Patent Laid-Open No. 2003-206475.

When the fine particles having a heat resistant temperature of 150 ° C. or higher are plate-like, the fine particles having a heat resistant temperature of 150 ° C. or higher are oriented in the porous layer so that the flat plate surface is substantially parallel to the surface of the porous layer. It is preferable to use a separator having such a porous layer, and the occurrence of a short circuit of the battery can be suppressed more favorably. This is because the fine particles having a heat-resistant temperature of 150 ° C. or more are oriented as described above, and the fine particles having a heat-resistant temperature of 150 ° C. or more are arranged so as to overlap each other on a part of the flat plate surface. It is considered that the gap (through hole) from the surface to the other surface is formed in a curved shape rather than a straight line (that is, the curvature becomes large), and this allows the lithium dendrite to penetrate the porous layer. Since it can prevent, it is estimated that generation | occurrence | production of a short circuit is suppressed more favorably.

For example, the aspect ratio (the ratio of the maximum length in the plate-like particles to the thickness of the plate-like particles) is 5 or more as the form when the fine particles having a heat-resistant temperature of 150 ° C. or higher are plate-like particles. Preferably, it is 10 or more, more preferably 100 or less, and even more preferably 50 or less. Further, the average value of the ratio of the major axis direction length to the minor axis direction length of the flat plate surface of the grains is preferably 0.3 or more, more preferably 0.5 or more (ie, the major axis length). And the length in the minor axis direction may be the same). When the fine particles having a plate-like heat-resistant temperature of 150 ° C. or higher have the aspect ratio or the average value of the ratio of the length in the long axis direction to the length in the short axis direction of the flat plate surface, the short-circuit preventing action is achieved. More effective.

In addition, the average value of the ratio of the long axis direction length to the short axis direction length of the flat plate surface when the fine particles having a heat resistant temperature of 150 ° C. or more are plate-like is taken by, for example, a scanning electron microscope (SEM) It can obtain | require by image-analyzing the done image. Further, the aspect ratio in the case where the fine particles having a heat resistant temperature of 150 ° C. or higher are plate-like can also be obtained by image analysis of an image taken by SEM.

Further, the fine particles having a heat resistant temperature of 150 ° C. or higher may be particles containing two or more materials constituting the fine particles having various heat resistant temperatures exemplified above of 150 ° C. or higher.

The average particle diameter of the fine particles having a heat resistant temperature of 150 ° C. or higher is preferably 0.01 μm or more, more preferably 0.1 μm or more, preferably 15 μm or less, more preferably 5 μm or less.

As used herein, the average particle size of the fine particles having a heat resistant temperature of 150 ° C. or higher is determined by, for example, using a laser scattering particle size distribution meter (for example, “LA-920” manufactured by HORIBA) to It can be defined as the number average particle diameter measured by dispersing fine particles having a heat resistant temperature of 150 ° C. or higher in a medium in which the fine particles having a heat resistant temperature of 150 ° C. or higher do not swell.

The specific surface area of the fine particles having a heat resistant temperature of 150 ° C. or higher is preferably 100 m ² / g or less, more preferably 50 m ² / g or less, and further preferably 30 m ² / g or less. If the specific surface area is too large, the amount of the binder for binding fine particles to each other, or binding the fine particles to the substrate or electrode may be too large, and the output characteristics may be deteriorated when the battery is used. In addition, there is a possibility that the moisture adsorbed on the surface of the fine particles increases and the battery characteristics of the nonaqueous battery are deteriorated. On the other hand, a preferable lower limit value of the specific surface area of the fine particles having a heat resistant temperature of 150 ° C. or higher is 1 m ² / g. Here, the specific surface area is a value measured by a BET method using nitrogen gas.

When the porous layer of the present invention uses fine particles having a high heat resistance temperature of 150 ° C. or higher as described above, its action can suppress thermal shrinkage at high temperatures and improve dimensional stability. . In addition, when the porous layer of the present invention containing fine particles having a high heat resistance of 150 ° C. or higher is integrated with an electrode (positive electrode or negative electrode), the dimensions of the porous layer at a high temperature Stability can be further enhanced.

Furthermore, even when the separator is composed of the porous layer of the present invention containing fine particles having a heat resistance of 150 ° C. or higher and a porous resin film, the porous resin film is dimensional stability at high temperatures. Even if it is inferior to the above, since it is integrated with a porous layer having good dimensional stability at high temperature by the action of fine particles having a heat resistant temperature of 150 ° C. or higher, thermal shrinkage of the porous resin film is suppressed, The overall dimensional stability of the separator at high temperatures is improved. Therefore, in the separator of the present invention using the porous layer of the present invention, for example, the occurrence of a short circuit due to heat shrinkage that occurred in a separator composed only of a conventional PE porous film (PE microporous film). Therefore, the reliability and safety when the inside of the battery is abnormally overheated can be further improved.

The porous layer of the present invention may contain a fibrous material having a heat resistant temperature of 150 ° C. or higher. For example, in the case where the separator is constituted only by the porous layer and the porous layer is not integrated with the electrode, the fibrous material is included from the viewpoint of reinforcing the porous layer and improving its handleability. It is preferable that the fibrous material is the main component of the separator. Also, when a separator is constituted by a porous layer and a porous resin film, or when the porous layer is integrated with an electrode, a fibrous material having a heat resistant temperature of 150 ° C. or more is contained for reinforcement. be able to.

In particular, the porous layer contains a material that can be melted at a temperature of 140 ° C. or lower to block the pores of the porous layer (separator) and provide a function of blocking the movement of ions in the separator (so-called shutdown function). In this case (details will be described later), a fibrous material having a heat-resistant temperature of 150 ° C. or higher is also contained in the porous layer. Even if the temperature rises, the shape can be kept more stable. On the other hand, even when the shutdown function is not given, a separator configured using a porous layer that also uses a fibrous material having a heat resistant temperature of 150 ° C. or higher substantially does not deform even at a temperature of 150 ° C. Can be eliminated.

The fibrous material has a heat resistant temperature of 150 ° C. or higher, has an electrical insulating property, is electrochemically stable, and further has an electrolyte solution described in detail below and fine particles having a heat resistant temperature of 150 ° C. or higher. If it is stable to the solvent used for the composition for forming a porous layer containing the above, there is no particular limitation. The “fibrous material” in the present specification means that having an aspect ratio [length in the longitudinal direction / width (diameter) in a direction perpendicular to the longitudinal direction] of 4 or more. The aspect ratio of the fibrous material is preferably 10 or more.

Specific constituent materials of the fibrous material include, for example, cellulose, modified cellulose (such as carboxymethyl cellulose), polypropylene (PP), polyester [polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT). And the like], resins such as polyacrylonitrile (PAN), aramid, polyamideimide, and polyimide; inorganic materials (inorganic oxides) such as glass, alumina, and silica; and the like. The fibrous material may contain one kind of these constituent materials, or may contain two or more kinds. In addition to the above-described constituent materials, the fibrous material may contain various known additives (for example, an antioxidant in the case of a resin) as necessary. Absent.

Note that the fibrous material may be subjected to a surface treatment such as a corona discharge treatment or a treatment with a surfactant in order to enhance the adhesion with fine particles having a heat resistant temperature of 150 ° C. or higher.

The diameter of the fibrous material may be equal to or less than the thickness of the porous layer, but is preferably 0.01 to 5 μm, for example. If the diameter is too large, the entanglement between the fibrous materials may be insufficient, and the strength of the sheet-like material constituted by these, and consequently the strength of the porous layer may be reduced, making it difficult to handle. On the other hand, if the diameter is too small, the pores of the porous layer become too small, and the ion permeability tends to decrease, which may reduce the load characteristics of the battery.

The fibrous material may be contained in the porous layer in a state where each fibrous material is independent, and the porous layer in a sheet-like material (woven fabric, non-woven fabric, etc.) composed of the fibrous material. It may be included.

For example, the state of the fibrous material in the porous layer (sheet-like material) is preferably such that the angle of the long axis (axis in the long direction) to the separator surface is 30 ° or less on average, 20 ° The following is more preferable.

The content of the fine particles having a heat resistant temperature of 150 ° C. or higher in the porous layer is the total volume of the constituent components of the porous layer from the viewpoint of more effectively exerting the effect of using the fine particles having a heat resistant temperature of 150 ° C. or higher. (The total volume excluding the void portion. The same applies hereinafter for the content of each component of the porous layer.) It is preferably 10% by volume or more, more preferably 30% by volume or more, and 40% by volume. It is still more preferable that it is above.

In the case where the porous layer does not contain the fibrous material and includes a heat-fusible fine particle or a swellable fine particle, which will be described later, and has a shutdown function, the fine particle having a heat resistant temperature of 150 ° C. or higher is used. The upper limit of the volume ratio is preferably 80% by volume, for example. On the other hand, when the porous layer does not have a shutdown function, the volume ratio of the fine particles having a heat-resistant temperature of 150 ° C. or higher may be higher, for example, 99.5% by volume or less.

On the other hand, in the case of a porous layer containing the fibrous material described above and containing a heat-fusible fine particle or a swellable fine particle, which will be described later, and having a shutdown function, a fine particle having a heat resistant temperature of 150 ° C. or higher is used. The upper limit of the volume ratio is preferably 70% by volume, for example. When the porous layer does not have a shutdown function, the volume ratio of the fine particles having a heat resistant temperature of 150 ° C. or higher may be a higher ratio, for example, 80% by volume or less.

In addition, when the porous layer contains the fibrous material, the content of the fibrous material in the porous layer is the configuration of the porous layer from the viewpoint of more effectively exerting the effect of using the fibrous material. The total volume of the components is preferably 10% by volume or more, and more preferably 30% by volume or more. On the other hand, in the porous layer containing the fibrous material, if the content of the fibrous material is too large, the content of other components (such as fine particles having a heat-resistant temperature of 150 ° C. or more) decreases, Therefore, the content of the fibrous material is preferably 90% by volume or less and more preferably 70% by volume or less in the total volume of the constituent components of the porous layer. preferable.

Furthermore, the content of the organic binder in the porous layer is preferably 0.5% by mass or more in the total amount of the constituent components of the porous layer from the viewpoint of satisfactorily exerting the action of these organic binders. On the other hand, when the content of the organic binder is too large, the content of other components (such as fine particles having a heat-resistant temperature of 150 ° C. or higher) decreases, and the action of these other components may be reduced. The content of the organic binder in the layer is preferably 10% by mass or less in the total amount of the constituent components of the porous layer.

A shutdown function can be imparted to the porous layer of the present invention. In order to obtain a porous layer having a shutdown function, for example, the porous layer swells in hot-melt fine particles that melt at 80 to 150 ° C. or in a non-aqueous electrolyte, and the degree of swelling increases with an increase in temperature. What is necessary is just to contain the swelling fine particle which increases. It should be noted that both the hot-melt fine particles and the swellable fine particles may be added to the porous layer, or a composite of these may be added.

The shutdown function in the porous layer can be evaluated by, for example, an increase in resistance due to the temperature of the model cell. That is, a positive electrode, a negative electrode, and an electrolytic solution are provided, and a porous layer is provided on an electrode mixture layer of at least one of the positive electrode and the negative electrode, or a positive electrode, a negative electrode, a separator, and an electrolytic solution are provided, and the separator A model cell having a porous layer on at least one side of the sample cell was prepared, the model cell was held in a high-temperature bath, and the internal resistance value of the model cell was measured while increasing the temperature at a rate of 5 ° C./min. By measuring the temperature at which the internal resistance value is 5 times or more that before heating (resistance value measured at room temperature), this temperature can be evaluated as the shutdown temperature of the porous layer (of the present invention described later) The same shutdown method can be used for the nonaqueous battery separator).

A porous material containing a heat-meltable fine particle that melts at 80 to 150 ° C., that is, a material having a melting temperature of 80 to 150 ° C. measured using a differential scanning calorimeter (DSC) according to JIS K 7121. In the layer, when the porous layer is exposed to 80 to 150 ° C. (or higher temperature), the hot-melt fine particles are melted and the pores of the porous layer are closed. The movement of lithium ions between the two is inhibited, and a rapid discharge reaction at high temperatures is suppressed. Therefore, in this case, the shutdown temperature of the porous layer evaluated by the increase in internal resistance is not less than the melting point of the heat-meltable fine particles and not more than 150 ° C. The melting point (the melting temperature) of the heat-meltable fine particles is more preferably 140 ° C. or lower.

Specific examples of the constituent material of the heat-meltable fine particles include polyethylene (PE), copolymerized polyolefin having a structural unit derived from ethylene of 85 mol% or more, polypropylene (PP), or polyolefin derivative (chlorinated polyethylene, chlorinated polypropylene, etc. ), Polyolefin wax, petroleum wax, carnauba wax and the like. Examples of the copolymer polyolefin include an ethylene-vinyl monomer copolymer, more specifically, an ethylene-vinyl acetate copolymer (EVA), an ethylene-methyl acrylate copolymer, or an ethylene-ethyl acrylate copolymer. it can. Moreover, polycycloolefin etc. can also be used. The heat-meltable fine particles may have only one kind of these constituent materials, or may have two or more kinds. Among these, PE, polyolefin wax, or EVA having a structural unit derived from ethylene of 85 mol% or more is preferable. Further, the heat-meltable fine particles may contain various known additives (for example, antioxidants) added to the resin as necessary, in addition to the above-described constituent materials. Absent.

The particle diameter of the heat-meltable fine particles is a number average particle diameter measured by the same measurement method as fine particles having a heat resistant temperature of 150 ° C. or higher, and is preferably 0.001 μm or more, for example, 0.1 μm or more. More preferably, it is preferably 15 μm or less, and more preferably 1 μm or less.

In a battery having a porous layer having swellable fine particles that can swell in a non-aqueous electrolyte and whose degree of swelling increases with an increase in temperature, the non-aqueous electrolysis is caused by swelling of the swellable fine particles when the inside becomes high temperature. It absorbs the liquid and expands greatly (hereinafter, the function of increasing the degree of swelling as the temperature rises in the swellable fine particles is called “thermal swellability”), thereby significantly increasing the conductivity of Li ions in the porous layer. Therefore, the internal resistance of the battery is increased, and the shutdown function can be reliably ensured. As the swellable fine particles, those having a temperature showing the above-mentioned heat swellability are preferably 75 to 135 ° C.

Examples of such swellable fine particles having thermal swellability include cross-linked polystyrene (PS), cross-linked acrylic resin [for example, cross-linked polymethyl methacrylate (PMMA)], cross-linked fluororesin [for example, cross-linked polyvinylidene fluoride (PVDF) ] Is preferred, and cross-linked PMMA is particularly preferred.

The particle size of the swellable fine particles is a number average particle size measured by dispersing the fine particles in a non-swelling medium (for example, water) using a laser scattering particle size distribution analyzer (for example, “LA-920” manufactured by HORIBA). It is preferably 1 to 20 μm.

As commercially available products of swellable fine particles, for example, cross-linked PMMA “Gantz Pearl (product name)” manufactured by Ganz Kasei Co., Ltd., and cross-linked PMMA “RSP1079 (product name)” manufactured by Toyo Ink Co., Ltd. are available.

In addition, when a thermal shutdown fine particle or a swelling fine particle is included in the porous layer so as to have a shutdown function, the thermal meltable fine particle and / or swelling in the porous layer is required in order to ensure a good shutdown function. The content of the conductive fine particles is preferably 5 to 70% by volume in the total volume of the constituent components of the porous layer. If the content of these fine particles is too small, the shutdown effect due to the inclusion of these may be reduced, and if too large, the content of fine particles or fibrous materials having a heat resistance temperature of 150 ° C. or higher in the porous layer. Therefore, the effect secured by these may be reduced.

The thickness of the porous layer of the present invention is preferably 0.5 μm or more, more preferably 1 μm or more, further preferably 2 μm or more, and preferably 10 μm or less, preferably 5 μm or less. It is more preferable that

In addition, the porosity of the porous layer of the present invention is preferably 20 to 60%. The porosity of the porous layer can be calculated by calculating the sum of each component i from the thickness of the porous layer, the mass per area, and the density of the constituent components using the following formula (3).
P = 100− (Σa _i / ρ _i ) × (m / t) (3)

Here, in the formula (3), a _i : ratio of the component i expressed by mass%, ρ _i : density of the component i (g / cm ³ ), m: mass per unit area of the porous layer (g / Cm ² ), t: thickness of the porous layer (cm).

The porous layer of the present invention is for forming a porous layer containing fine particles having an heat-resistant temperature of 150 ° C. or more and an organic binder, as well as fibrous materials, heat-meltable fine particles, swellable fine particles and the like used as necessary. The composition (composition containing a solvent) is used on a porous resin film (in the case of the separator for a non-aqueous battery of the present invention) as a base material, or an electrode mixture layer of the electrode for a non-aqueous battery (of the present invention). The electrode can be formed on a nonaqueous battery electrode) and then dried.

When the porous layer contains a fibrous sheet (woven fabric, non-woven fabric, etc.), for example, the porous layer forming composition is impregnated with the sheet, and the gap is formed as necessary. The composition for forming a porous layer is promoted to penetrate into the voids of the sheet-like material, or the composition for forming a porous layer is applied to the sheet-like material through the gap after being applied. It is also possible to form a porous layer through a step of drying after intruding into the voids of the sheet-like material.

The composition for forming a porous layer contains fine particles having an heat resistant temperature of 150 ° C. or more and an organic binder, as well as fibrous materials, hot-melt fine particles, swellable fine particles, and the like, which are used as necessary. (Including a dispersion medium, the same shall apply hereinafter). The organic binder can be dissolved in a solvent. The solvent used in the composition for forming a porous layer may be any solvent as long as it can uniformly disperse the fine particles, and can uniformly dissolve or disperse the organic binder. For example, an aromatic hydrocarbon such as toluene. Common organic solvents such as francs such as tetrahydrofuran, ketones such as methyl ethyl ketone and methyl isobutyl ketone are preferably used. In addition, for the purpose of controlling the interfacial tension, alcohols (ethylene glycol, propylene glycol, etc.) or various propylene oxide glycol ethers such as monomethyl acetate may be appropriately added to these solvents. In addition, when the organic binder is water-soluble or used as an emulsion, water may be used as a solvent. In this case, alcohols (methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, etc.) are appropriately added. It is also possible to control the interfacial tension.

The composition for forming a porous layer preferably has a solid content including fine particles having an heat resistant temperature of 150 ° C. or higher and an organic binder, for example, 10 to 80% by mass.

When plate-like particles are used as fine particles having a heat-resistant temperature of 150 ° C. or higher, the composition for forming a porous layer is used as a base material (porous resin film, electrode, or fibrous sheet-like material) in order to increase the orientation. ) A method of applying a share of the above composition; a method of using a composition for forming a porous layer having a high solid content concentration (for example, 50 to 80% by mass); and fine particles having a heat resistant temperature of 150 ° C. or more. Disperse in a solvent using various mixing / stirring devices such as dispersers, agitators, homogenizers, ball mills, attritors, jet mills, dispersing devices, etc., and a binder (and fibrous material if necessary) , Heat-meltable fine particles, swellable fine particles, etc.), and a method for using the composition for forming a porous layer prepared by adding and mixing; dispersants such as fats and oils, surfactants and silane coupling agents on the surface A method for using a porous layer forming composition prepared by using fine particles having a heat-resistant temperature of 150 ° C. or higher whose surface has been modified; fine particles having a heat-resistant temperature of 150 ° C. or higher having different shapes, diameters or aspect ratios A method using a composition for forming a porous layer prepared in combination with a composition; a method for controlling drying conditions after the composition for forming a porous layer is applied on a substrate; a separator having the porous layer of the present invention In the case of (separator of the present invention), a method of pressurizing or heating and pressing the whole separator; a method of applying a magnetic field before drying after applying the porous layer forming composition on a substrate; These methods can be employed alone or in combination of two or more methods.

The nonaqueous battery separator of the present invention (hereinafter simply referred to as “separator”) is obtained by forming the porous layer of the present invention on a porous resin film.

In the separator of the present invention, when the shutdown function is secured by the porous resin film, the same resin (thermoplastic resin) as the resin constituting the heat-meltable fine particles is used as the resin constituting the porous resin film. be able to. The shutdown temperature of the porous resin film is desirably set in the range of 80 ° C. to 150 ° C. Therefore, it is desirable to use a thermoplastic resin having a melting point of 80 to 150 ° C.

On the other hand, when the heat resistance of the separator is emphasized and the shutdown function is not provided, a heat resistant porous resin film can be used. As a specific constituent material of such a porous resin film, the heat resistant temperature is 150 ° C. or more, it is stable to a non-aqueous electrolyte used in a battery, and further stable to a redox reaction inside the battery. Any resin can be used. More specifically, heat-resistant resins such as polyimide, polyamideimide, aramid, polytetrafluoroethylene, polysulfone, polyurethane, PAN, polyester (PET, PBT, PEN, etc.) can be mentioned.

The porous resin film includes, for example, a porous film composed of the above-described exemplary resins used in conventionally known non-aqueous batteries, that is, ions produced by a solvent extraction method, a dry or wet stretching method, and the like. A permeable porous film (microporous film) can be used. In addition, a film microporous by a foaming method using a drug, supercritical CO ₂ or the like can also be used.

In the separator of the present invention, because of the action of the porous layer of the present invention, it is possible to ensure good heat resistance (heat shrinkage resistance) even when a porous resin film that is easily heat-shrinkable is applied. It is preferable to employ a porous resin film that can ensure a good shutdown function, and it is more preferable to use a porous film (microporous film) made of polyolefin (PE, PP, ethylene-propylene copolymer, etc.).

In the separator of the present invention, the porous layer and the porous resin film do not need to be one each, and one or both may be two or more layers, but the number of layers of the separator is excessively increased. For example, the total number of layers of the porous layer and the porous resin film is preferably 5 or less.

From the viewpoint of enhancing the short-circuit prevention effect of the non-aqueous battery to which the separator is applied, ensuring the strength of the separator, and improving its handleability, the thickness of the separator of the present invention is preferably 3 μm or more, for example. More preferably, it is 5 μm or more. On the other hand, from the viewpoint of further increasing the energy density of the nonaqueous battery to which the separator is applied, the thickness of the separator is preferably 50 μm or less, and more preferably 30 μm or less.

In addition, when the thickness of the porous layer is X (μm) and the thickness of the porous resin film is Y (μm), the ratio Y / X between X and Y is 1 to 20, and the thickness of the entire separator is It is preferable to satisfy a suitable value. If Y / X is too large, the porous layer becomes too thin. For example, when the dimensional stability of the porous resin film at high temperatures is poor, the effect of suppressing the thermal shrinkage may be reduced. On the other hand, if Y / X is too small, the porous layer becomes too thick, increasing the thickness of the entire separator, and possibly causing deterioration of battery characteristics such as load characteristics. When the separator has a plurality of porous layers, the thickness X is the total thickness, and when the separator has a plurality of porous resin films, the thickness Y is the total thickness.

When the thickness of the porous resin film (when the separator has a plurality of porous resin films, the total thickness) is expressed by a specific value, it is preferably 5 μm or more, and 30 μm or less. It is preferable. Regarding the thickness of the porous layer in the separator, when the separator has a plurality of porous layers, it is preferable that the total thickness satisfies the preferred thickness of the porous layer described above.

Further, the separator of the present invention preferably has a thermal shrinkage rate at 150 ° C. of 5% or less in the nonaqueous electrolytic solution (the solvent) measured by the method described in the examples. By using the separator having the configuration described so far, such a heat shrinkage rate can be ensured.

In addition, the porosity of the separator is preferably 20% or more, and preferably 30% or more in a dried state, in order to ensure the amount of the nonaqueous electrolyte retained and to improve the ion permeability. It is more preferable. On the other hand, from the viewpoint of ensuring the strength of the separator and preventing internal short circuit, the porosity of the separator is preferably 70% or less, more preferably 60% or less, in a dry state. Note that the porosity of the separator: P (%) is obtained by setting m as the mass per unit area of the separator (g / cm ² ) and t as the thickness of the separator (cm) in the above formula (3). , Can be obtained using the above equation (3).

Furthermore, in the said Formula (3), m is the mass per unit area (g / cm < ² >) of a porous resin film, and t is the thickness (cm) of a porous resin film, The said Formula (3) Can also be used to determine the porosity of the porous resin film: P (%). The porosity of the porous resin film obtained by this method is preferably 30 to 70%.

Furthermore, the strength of the separator is desirably 50 g or more in terms of piercing strength using a needle having a diameter of 1 mm. If the piercing strength is too low, a short circuit may occur due to the piercing of the separator when lithium dendrite crystals are generated.

The air permeability of the separator is measured by a method in accordance with JIS P 8117, and is a Gurley value indicated by the number of seconds that 100 ml of air passes through the membrane under a pressure of 0.879 g / mm ² , and is 10 to 300 sec. It is desirable to be. If the air permeability is too high, the ion permeability is reduced, and if it is too low, the strength of the separator may be reduced.

Furthermore, it is desirable that the Gurley value of the separator satisfies the relationship of the following formula (4).
Gs ≦ max {Ga, Gb} +10 (4)

In the above formula (4), Gs: Gurley value of the separator, Ga: Gurley value of the porous resin film, Gb: Gurley value of the porous layer of the present invention, max {a, b}: whichever is greater than a or b Is. However, Gb is calculated | required using following formula (5).
Gb = Gs-Ga (5)

The puncture strength and air permeability described above can be ensured by using a separator having the structure described above.

In the separator of the present invention, the 180 ° peel strength between the porous layer and the porous resin film is preferably 0.6 N / cm or more, and more preferably 1.0 N / cm or more. The peel strength here is a value measured by the following method. An adhesive tape is attached to a 2 cm × 2 cm region on the surface of the porous layer on a test piece cut out in a size of 5 cm × 2 cm from the separator. The adhesive tape has a width of 2 cm and a length of about 5 cm, and is attached so that one end of the adhesive tape and one end of the porous layer are aligned. Then, using a tensile tester, the end of the test piece on the opposite side of the adhesive tape and the end of the adhesive tape attached to the test piece on the opposite side of the test piece Gripping and pulling at a pulling speed of 10 mm / min to measure the strength when the porous layer is peeled off.

In the separator of the present invention, the porous layer (the porous layer of the present invention) is represented by the general formula (1) and the N-vinylcarboxylic amide represented by the general formula (1), which is excellent in adhesiveness. Since a copolymer with an unsaturated carboxylic acid monomer that satisfies the copolymerization ratio is used as the organic binder, the peel strength between the porous layer and the porous resin film is Can be raised like. And a copolymer of the N-vinylcarboxylic amide represented by the general formula (1) and the unsaturated carboxylic acid monomer represented by the general formula (2), wherein the copolymerization ratio is What is filled is excellent in resistance in a high-temperature non-aqueous electrolyte (non-aqueous electrolyte solvent), so even if the temperature of the non-aqueous battery in which the separator of the present invention is used becomes high, the porous layer Since the peel strength between the film and the porous resin film can be maintained at a high value, it is possible to highly suppress the shrinkage of the entire separator due to the action of the porous layer, and to construct a safer non-aqueous battery it can.

The nonaqueous battery electrode of the present invention (hereinafter simply referred to as “electrode”) is obtained by forming the porous layer of the present invention on an electrode mixture layer (positive electrode mixture layer or negative electrode mixture layer). The electrode of the present invention is used for a positive electrode or a negative electrode of a nonaqueous battery. In addition, as a battery in which the electrode of the present invention is used, there are a non-aqueous primary battery and a non-aqueous secondary battery. Hereinafter, the main non-aqueous secondary battery is used as a battery in which the electrode of the present invention is used. Details of the electrode having a configuration suitable for the above will be described.

As an electrode of the present invention when used for a positive electrode of a nonaqueous battery, for example, an electrode mixture layer (positive electrode mixture layer) containing a positive electrode active material, a conductive additive, a binder, and the like is used. Alternatively, a structure having a structure in which the porous layer of the present invention is formed on both electrode mixture layers on both surfaces is exemplified.

Examples of the positive electrode active material include lithium cobalt oxides such as LiCoO ₂ ; lithium manganese oxides such as LiMnO ₂ and Li ₂ MnO ₃ ; lithium nickel oxides such as LiNiO ₂ ; LiMn ₂ O ₄ and Li _4/3 Ti _5/3 O ₄ and other spinel-structured lithium-containing composite oxides; LiFePO ₄ and other olivine-structured lithium-containing composite oxides; oxides obtained by substituting the above-mentioned oxides with various elements; Only one of these may be used, or two or more may be used in combination.

Examples of the conductive auxiliary agent related to the positive electrode mixture layer include graphites such as natural graphite (flaky graphite, etc.) and artificial graphite; acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, etc. It is preferable to use carbon materials such as carbon blacks; carbon fibers; and conductive fibers such as metal fibers; carbon fluorides; metal powders such as aluminum; zinc oxide; and conductive materials such as potassium titanate. Conductive whiskers; conductive metal oxides such as titanium oxide; organic conductive materials such as polyphenylene derivatives; and the like can also be used.

Examples of the binder related to the positive electrode mixture layer include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyvinyl pyrrolidone (PVP), and the like.

For example, a positive electrode mixture containing a positive electrode active material, a conductive additive, a binder, and the like is dispersed in a solvent such as N-methyl-2-pyrrolidone (NMP) or water to form a paste-like or slurry-like positive electrode mixture. An agent-containing composition is prepared (however, the binder may be dissolved in a solvent), applied to one or both sides of the current collector, dried, and then subjected to a calender treatment as necessary. Using the positive electrode as a base material, it can be produced through the step of forming the porous layer of the present invention on the positive electrode mixture layer by the method described above. However, the positive electrode is not limited to those manufactured by the above method, and may be manufactured by other methods.

As the positive electrode current collector, aluminum foil, punching metal, net, expanded metal, or the like can be used, but aluminum foil is usually used. The thickness of the positive electrode current collector is preferably 10 to 30 μm.

Further, a lead body for electrical connection with other members in the non-aqueous battery may be formed on the positive electrode according to a conventional method, if necessary.

As the composition of the positive electrode mixture layer, for example, the content of the positive electrode active material is preferably 80.0 to 99.8% by mass, and the content of the conductive auxiliary agent is 0.1 to 10% by mass. The binder content is preferably 0.1 to 10% by mass. The thickness of the positive electrode mixture layer is preferably 1 to 100 μm per side of the current collector.

As an electrode of the present invention when used for a negative electrode of a nonaqueous battery, for example, an electrode mixture layer (a negative electrode mixture layer) containing a negative electrode active material and a binder, and further, if necessary, a conductive additive, etc. And a structure in which the porous layer of the present invention is formed on one or both surfaces of the current collector and on the electrode mixture layer.

The negative electrode active material may be any material that can be doped / undoped with lithium ions. For example, graphite, pyrolytic carbons, cokes, glassy carbon, fired organic polymer compound, mesocarbon microbeads, carbon Examples thereof include carbonaceous materials such as fibers and activated carbon. Moreover, lithium or a lithium-containing compound can also be used as the negative electrode active material. Examples of the lithium-containing compound include tin oxide, silicon oxide, nickel-silicon alloy, magnesium-silicon alloy, tungsten oxide, lithium iron composite oxide, lithium-aluminum, and lithium-lead. And lithium alloys such as lithium-indium, lithium-gallium, and lithium-indium-gallium. Some of these exemplary negative electrode active materials do not contain lithium at the time of manufacture, but are in a state containing lithium at the time of charging.

As the binder relating to the negative electrode mixture layer, the same binders as those exemplified above as the binder relating to the positive electrode mixture layer can be used.

When the negative electrode mixture layer contains a conductive additive, the same conductive assistants as those exemplified above as the conductive additive related to the positive electrode mixture layer can be used.

The negative electrode includes, for example, a negative electrode active material, a binder, and, if necessary, a negative electrode mixture containing a conductive auxiliary agent in a solvent such as NMP or water to disperse a paste or slurry-like positive electrode mixture. (However, the binder may be dissolved in a solvent.) This is applied to one or both sides of the current collector, dried, and then calendered as necessary. As a material, it can manufacture through the process of forming the porous layer of this invention on the negative mix layer by the said method. However, the negative electrode is not limited to those manufactured by the above method, and may be manufactured by other methods.

For the current collector of the negative electrode, for example, a foil made of copper, stainless steel, nickel, titanium, or an alloy thereof, a punched metal, an expanded metal, a net, or the like can be used. Usually, a copper having a thickness of 5 to 30 μm is used. A foil is preferably used.

In addition, a lead body for electrical connection with other members in the nonaqueous battery may be formed on the negative electrode according to a conventional method, if necessary.

In the negative electrode mixture layer, for example, the content of the negative electrode active material is preferably 70 to 99% by mass, and the content of the binder is preferably 1 to 30% by mass. In the case where a conductive assistant is used, the content of the conductive assistant in the negative electrode mixture layer is preferably 1 to 20% by mass. Further, the thickness of the negative electrode mixture layer is preferably 1 to 100 μm per side of the current collector.

The nonaqueous battery of the present invention has a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte, and the separator is the separator of the present invention, or has a positive electrode, a negative electrode, and a nonaqueous electrolyte, and the positive electrode and the negative electrode It is sufficient that at least one of the electrodes is the electrode of the present invention, and there are no particular restrictions on the other configurations and structures, and various configurations employed in conventionally known non-aqueous batteries such as lithium secondary batteries And structure can be applied.

In the nonaqueous battery of the present invention, when the separator of the present invention is not used, the porous layer (the porous layer of the present invention) according to the electrode of the present invention plays the role of a separator, but a separate separator is used. The porous resin film for constituting the separator can be used as the separator in that case. In addition, in the nonaqueous battery of the present invention, when the electrode of the present invention is not used as a positive electrode, the positive electrode has the same configuration as the electrode of the present invention except that it has the porous layer of the present invention. Can be used. Furthermore, in the non-aqueous battery of the present invention, when the electrode of the present invention is not used as a negative electrode, the negative electrode having the same configuration as that of the electrode of the present invention is used except that the positive electrode has the porous layer of the present invention. Can be used.

In the nonaqueous battery of the present invention, the positive electrode and the negative electrode are laminated with a separator interposed therebetween, or are laminated so that a porous layer formed on at least one electrode mixture layer is interposed therebetween. It is used in the form of a laminated body (laminated electrode body) or a wound body (wound electrode body) obtained by winding this laminated body in a spiral shape.

As the non-aqueous electrolyte of the non-aqueous battery, as described above, a solution (non-aqueous electrolyte) in which a lithium salt is dissolved in an organic solvent is used. The lithium salt is not particularly limited as long as it dissociates in a solvent to form Li + ions and does not cause a side reaction such as decomposition in a voltage range used as a battery. For example, inorganic lithium salts such as LiClO ₄ , LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ ; LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , Li ₂ C ₂ F ₄ (SO ₃ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiC _n F _{2n + 1} SO ₃ (n ≧ 2), LiN (R _f OSO ₂ ) ₂ [where R _f is a fluoroalkyl group], etc .; Can be used.

The organic solvent used in the non-aqueous electrolyte is not particularly limited as long as it dissolves the lithium salt and does not cause side reactions such as decomposition in the voltage range used as a battery. For example, cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate and vinylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate; chain esters such as methyl propionate; cyclic esters such as γ-butyrolactone; Chain ethers such as ethane, diethyl ether, 1,3-dioxolane, diglyme, triglyme and tetraglyme; cyclic ethers such as dioxane, tetrahydrofuran and 2-methyltetrahydrofuran; nitriles such as acetonitrile, propionitrile and methoxypropionitrile; Sulfites such as ethylene glycol sulfite; and the like, and these may be used alone. , It may be used in combination of two or more thereof. In order to obtain a battery with better characteristics, it is desirable to use a combination that can obtain high conductivity, such as a mixed solvent of ethylene carbonate and chain carbonate. In addition, vinylene carbonates, 1,3-propane sultone, diphenyl disulfide, cyclohexyl benzene, biphenyl, and fluorobenzene are used for the purpose of improving the safety, charge / discharge cycleability, and high-temperature storage properties of these non-aqueous electrolytes. Additives such as t-butylbenzene can also be added as appropriate.

The concentration of this lithium salt in the non-aqueous electrolyte is preferably 0.5 to 1.5 mol / l, more preferably 0.9 to 1.25 mol / l.

Also, instead of the organic solvent, melting at room temperature such as ethyl-methylimidazolium trifluoromethylsulfonium imide, heptyl-trimethylammonium trifluoromethylsulfonium imide, pyridinium trifluoromethylsulfonium imide, guanidinium trifluoromethylsulfonium imide A salt can also be used.

Furthermore, a polymer material that contains the non-aqueous electrolyte and gels may be added to make the non-aqueous electrolyte into a gel (gel electrolyte) for use in a battery. Polymer materials for making non-aqueous electrolyte into gel include PVDF, vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), PAN, polyethylene oxide, polypropylene oxide, ethylene oxide-propylene oxide copolymer And a known host polymer capable of forming a gel electrolyte, such as a crosslinked polymer having an ethylene oxide chain in the main chain or side chain, and a crosslinked poly (meth) acrylate.

Examples of the form of the non-aqueous battery of the present invention include a cylindrical shape (such as a rectangular tube shape or a cylindrical shape) using a steel can or an aluminum can as an outer can. Moreover, it can also be set as the soft package battery which used the laminated film which vapor-deposited the metal as an exterior body.

Hereinafter, the present invention will be described in detail based on examples. However, the following examples do not limit the present invention.

Example 1
<Preparation of positive electrode>
LiCoO _{2 as a} positive electrode active material: 90 parts by mass, carbon black as a conductive auxiliary agent: 5 parts by mass are added and mixed, and a solution in which 5 parts by mass of PVDF as a binder is dissolved in NMP is added to this mixture. The mixture was mixed to obtain a positive electrode mixture-containing slurry, which was passed through a 70-mesh net to remove a large particle size. This positive electrode mixture-containing slurry is uniformly applied to both sides of a positive electrode current collector made of an aluminum foil having a thickness of 15 μm, dried, and then compression-molded by a roll press machine to a total thickness of 105 μm, followed by cutting. Then, an aluminum lead body was welded to the exposed portion of the current collector to produce a strip-like positive electrode.

<Production of negative electrode>
Artificial graphite as a negative electrode active material: 95 parts by mass and PVDF as a binder: 5 parts by mass were mixed, and NMP was further added and mixed to prepare a negative electrode mixture-containing paste. This negative electrode mixture-containing paste is uniformly coated on both sides of a negative electrode current collector made of copper foil having a thickness of 10 μm, dried, and then compression-molded by a roll press machine to a total thickness of 100 μm, followed by cutting. Then, a nickel lead body was welded to the exposed portion of the current collector to produce a strip-shaped negative electrode.

<Preparation of non-aqueous electrolyte>
In a solvent mixture of ethylene carbonate, methyl ethyl carbonate and diethyl carbonate having a volume ratio of 10:10:30, LiPF ₆ was dissolved at a concentration of 1.0 mol / l, and vinylene carbonate was added to the total amount of the non-aqueous electrolyte. The non-aqueous electrolyte was prepared by adding 2.5% by mass.

<Preparation of separator>
Boehmite powder (plate shape, average particle size: 1 μm, aspect ratio: 10, specific surface area: 8 m ² / g): 4000 g, fine particles having a heat-resistant temperature of 150 ° C. or higher, are added to water: 4000 g in four portions, A uniform slurry was prepared by stirring at 2800 rpm for 5 hours with a disper. To this slurry was added 1600 g of a 5 mass% aqueous solution of a copolymer of N-vinylacetamide as an organic binder and sodium acrylate (copolymerization ratio 90:10, molecular weight: 500,000). Further, water was added and the mixture was stirred at room temperature until uniformly dispersed to prepare a slurry for forming a porous layer having a solid content concentration of 30% by mass.

The slurry for forming a porous layer is applied by a microgravure coater on a treated surface of a PE microporous membrane (thickness: 16 μm, porosity: 40%, PE melting point: 135 ° C.) subjected to corona discharge treatment on one side. And drying to form a porous layer, thereby obtaining a separator having a thickness of 20 μm.

<Battery assembly>
The separator obtained as described above was laminated while being interposed between the positive electrode and the negative electrode so that the porous layer was directed to the positive electrode side, and wound into a spiral shape to produce a wound electrode body. The obtained wound electrode body is put into an iron outer can (battery case) having a diameter of 18 mm and a height of 65 mm, and after sealing with a nonaqueous electrolyte, sealing is performed, and the nonaqueous water having the structure shown in FIG. A secondary battery was produced.

Here, the battery shown in FIG. 1 will be described. In the nonaqueous secondary battery shown in FIG. 1, the positive electrode 1 and the negative electrode 2 are spirally wound via the separator 3, and nonaqueous electrolysis is used as a wound electrode body. It is accommodated in the battery case 5 together with the liquid 4. In FIG. 1, in order to avoid complication, the current collectors used for manufacturing the positive electrode 1 and the negative electrode 2 are not shown, and each layer of the separator is not shown.

The battery case 5 is made of stainless steel, and an insulator 6 made of PP is disposed at the bottom of the battery case 5 prior to insertion of the wound electrode body. The sealing plate 7 is made of aluminum and has a disk shape. A thin portion 7a is provided at the center of the sealing plate 7, and a pressure introduction port 7b for allowing the battery internal pressure to act on the explosion-proof valve 9 around the thin portion 7a. As a hole. And the protrusion part 9a of the explosion-proof valve 9 is welded to the upper surface of this thin part 7a, and the welding part 11 is comprised. The thin-walled portion 7a provided on the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 are shown only on the cut surface for easy understanding on the drawing, and the contour behind the cut surface is The illustration is omitted. In addition, the welded portion 11 of the thin-walled portion 7a of the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 is also illustrated in an exaggerated state so as to facilitate understanding on the drawing.

The terminal plate 8 is made of rolled steel, has a nickel plating on the surface, and has a cap shape with a peripheral edge portion, and the terminal plate 8 is provided with a gas discharge port 8a. The explosion-proof valve 9 is made of aluminum and has a disk shape, and a central portion is provided with a protruding portion 9a having a tip portion on the power generation element side (lower side in FIG. 1) and a thin portion 9b. As described above, the lower surface of the protruding portion 9a is welded to the upper surface of the thin portion 7a of the sealing plate 7 to constitute the welded portion 11. The insulating packing 10 is made of PP and has an annular shape. The insulating packing 10 is arranged at the upper part of the peripheral edge of the sealing plate 7. The explosion-proof valve 9 is arranged at the upper part of the insulating packing 10 and insulates the sealing plate 7 and the explosion-proof valve 9. The gap between the two is sealed so that the non-aqueous electrolyte does not leak between the two. The annular gasket 12 is made of PP, the lead body 13 is made of aluminum, the sealing plate 7 and the positive electrode 1 are connected, an insulator 14 is disposed on the upper part of the wound electrode body, and the negative electrode 2 and the battery case 5 The bottom is connected by a lead body 15 made of nickel.

In this non-aqueous secondary battery, the thin-walled portion 7a of the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 are in contact with each other at the welded portion 11, and the peripheral portion of the explosion-proof valve 9 and the peripheral portion of the terminal plate 8 are in contact. Since the positive electrode 1 and the sealing plate 7 are connected by the lead body 13 on the positive electrode side, in the normal state, the positive electrode 1 and the terminal plate 8 are connected to the lead body 13, the sealing plate 7, the explosion-proof valve 9 and their welding. The portion 11 provides an electrical connection and functions normally as an electrical circuit.

When the battery is exposed to a high temperature and an abnormal situation occurs, gas is generated inside the battery and the internal pressure of the battery rises, the internal pressure rises and the central portion of the explosion-proof valve 9 is moved in the internal pressure direction. (The upper direction in FIG. 1) is deformed, and accordingly, the thin portion 7a integrated with the welded portion 11 is subjected to a shearing force to break the thin portion 7a, or the protruding portion of the explosion-proof valve 9 After the welded part 11 between 9a and the thin part 7a of the sealing plate 7 is peeled off, the thin part 9b provided in the explosion-proof valve 9 is cleaved and the gas is discharged from the gas outlet 8a of the terminal plate 8 to the outside of the battery. It is designed to prevent the battery from bursting.

The non-aqueous secondary battery of this example has a design electric capacity of 1400 mAh when charged to 4.2 V (the positive electrode potential is 4.3 V with respect to Li) (for all examples and comparative examples described later). The same applies to the battery).

Example 2
The same boehmite powder: 4000 g used in Example 1 was added to 4000 g of water in four portions, and the mixture was stirred with a disper at 2800 rpm for 5 hours to prepare a uniform slurry. To this slurry was added 1600 g of a 5 mass% aqueous solution of a copolymer of N-vinylacetamide, an organic binder, and sodium acrylate (copolymerization ratio 70:30 by mass ratio, molecular weight: 500,000). Further, water was added and the mixture was stirred at room temperature until it was uniformly dispersed to obtain a slurry having a solid content concentration of 30% by mass. To this slurry, a fluorosurfactant was added in an amount of 0.1 part by mass with respect to 100 parts by mass of water, and stirred until uniform to prepare a slurry for forming a porous layer.

A slurry having a thickness of 20 μm was obtained by applying the slurry for forming a porous layer using a gravure coater on the same microporous membrane made of PE as that used for producing the separator in Example 1, and then drying the slurry. . And the non-aqueous secondary battery was produced like Example 1 except having used the said separator.

Example 3
The same boehmite powder: 4000 g used in Example 1 was added to 4000 g of water in four portions, and the mixture was stirred with a disper at 2800 rpm for 5 hours to prepare a uniform slurry. To this slurry was added 1600 g of a 5 mass% aqueous solution of a copolymer of N-vinylacetamide as an organic binder and sodium acrylate (copolymerization ratio 90:10 by mass ratio, molecular weight: 1 million). Further, water was added and the mixture was stirred at room temperature until it was uniformly dispersed to obtain a slurry having a solid content concentration of 30% by mass. To this slurry, a fluorosurfactant was added in an amount of 0.1 part by mass with respect to 100 parts by mass of water, and stirred until uniform to prepare a slurry for forming a porous layer.

A separator having a thickness of 20 μm was prepared in the same manner as in Example 2 except that the slurry for forming the porous layer was used, and a nonaqueous secondary battery was prepared in the same manner as in Example 1 except that this separator was used. did.

Example 4
Instead of the PE microporous membrane, a microporous membrane in which three layers of PP layer and PE layer are laminated in the order of PP / PE / PP (thickness: 16 μm, porosity: 45%, thickness of each layer; PP layer: A separator was prepared in the same manner as in Example 3 except that 5 μm / PE layer: 6 μm / PP layer: 5 μm) was used. And the non-aqueous secondary battery was produced like Example 1 except having used this separator.

Example 5
The same boehmite powder: 4000 g used in Example 1 was added to 4000 g of water in four portions, and the mixture was stirred with a disper at 2800 rpm for 5 hours to prepare a uniform slurry. To this slurry, 4000 g of an aqueous dispersion (solid content concentration: 40% by mass) of PE fine particles (PE melting point: 135 ° C.), which are hot-melt fine particles, N-vinylacetamide, which is an organic binder, and sodium acrylate, 2100 g of an aqueous solution (copolymerization ratio is 90:10 by weight ratio, molecular weight: 500,000): 2100 g, and water is added so that the solid content concentration is 30% by mass. The mixture was stirred until it became uniform to obtain a slurry for forming a porous layer.

The porous layer forming slurry was dip coated on a PET nonwoven fabric (weighing 8 g / m ² , thickness 16 μm) to prepare a porous film (porous layer) having a thickness of 20 μm. A nonaqueous secondary battery was produced in the same manner as in Example 1 except that this porous membrane was used as a separator.

Example 6
Alumina fine particles (average particle size: 0.4 μm, specific surface area: 7 m ² / g) are used as fillers, and 4000 g of alumina powder is added to 4000 g of water in four portions, and stirred with a disper at 2800 rpm for 5 hours to form a uniform slurry. Was prepared. To this slurry, an aqueous dispersion (solid content concentration: 40% by mass) of PE fine particles (PE melting point: 135 ° C.) as heat-melting fine particles: 4000 g, an organic binder N-vinylacetamide, and an acrylic acid Na salt A copolymer (copolymerization ratio is 90:10 by mass ratio, molecular weight: 500,000) and a 5 mass% aqueous solution: 1600 g is added, and water is further added so that the solid content concentration becomes 30 mass%. The mixture was stirred until it became uniform to prepare a slurry for forming a porous layer.

The slurry for forming the porous layer is applied on the negative electrode mixture layer on both sides of the same negative electrode as that prepared in Example 1 using a gravure coater and dried, and a porous material having a thickness of 20 μm on one side of the negative electrode. A quality layer was formed.

A wound electrode body was prepared in the same manner as in Example 1 except that the same positive electrode as that prepared in Example 1 and the above-described negative electrode were used and a separator was not used, and this wound electrode body was used. A nonaqueous secondary battery was produced in the same manner as Example 1 except for the above.

Example 7
The same slurry for forming a porous layer as that prepared in Example 6 was applied on the negative electrode mixture layer on both sides of the same negative electrode as that prepared in Example 1 using a gravure coater and dried. A porous layer having a thickness of 10 μm was formed. Also, the same slurry for forming a porous layer as that prepared in Example 6 was applied on the positive electrode mixture layer on both sides of the same positive electrode as that prepared in Example 1 using a gravure coater and dried. A porous layer having a thickness of 10 μm per side was formed.

A wound electrode body was prepared in the same manner as in Example 6 except that the negative electrode and the positive electrode were used, and a non-aqueous secondary battery was performed in the same manner as in Example 1 except that this wound electrode body was used. Was made.

Comparative Example 1
The same boehmite powder: 4000 g used in Example 1 was added to 4000 g of water in four portions, and the mixture was stirred with a disper at 2800 rpm for 5 hours to prepare a uniform slurry. To this slurry was added 1200 g of a 5 mass% aqueous solution of poly N-vinylacetamide (a homopolymer of N-vinylacetamide, molecular weight 1 million) as an organic binder, and water was added until room temperature until evenly dispersed. And a slurry for forming a porous layer having a solid content concentration of 30% by mass was prepared. A separator was prepared in the same manner as in Example 1 except that this porous layer forming slurry was used, and a non-aqueous secondary battery was prepared in the same manner as in Example 1 except that this separator was used.

Comparative Example 2
The same boehmite particles: 4000 g as used in Comparative Example 1 were added to water: 4000 g in four portions, and the mixture was stirred with a disper at 2800 rpm for 5 hours to prepare a uniform slurry. To this slurry, 1200 g of a 5% by weight aqueous solution of a copolymer of N-vinylacetamide as an organic binder and sodium acrylate (copolymerization ratio is 40:60, molecular weight: 500,000) is added. The mixture was stirred at room temperature until it was uniformly dispersed to prepare a slurry for forming a porous layer. A separator was prepared in the same manner as in Example 1 except that this porous layer forming slurry was used, and a non-aqueous secondary battery was prepared in the same manner as in Example 1 except that this separator was used.

For the separators used in the nonaqueous secondary batteries of Examples 1 to 4 and Comparative Examples 1 and 2, the 180 ° peel strength between the porous layer and the porous resin film was measured by the method described above.

Also, separators used in the non-aqueous secondary batteries of Examples 1 to 4 and Comparative Examples 1 and 2, porous membranes (porous layers) used as separators in the non-aqueous secondary battery of Example 5, and Examples About the porous layer used for the non-aqueous secondary battery of 6 and 7, the thermal contraction rate measurement in a non-aqueous electrolyte solvent was performed.

For the separators related to the non-aqueous secondary batteries of Examples 1 to 4 and Comparative Examples 1 and 2, strip-shaped sample pieces having a MD direction and a TD direction of 5 cm and 10 cm, respectively, were cut out. Here, the MD direction is the machine direction during the production of the porous resin film, and the TD direction is a direction perpendicular thereto. This sample piece and a non-aqueous electrolyte solvent (a mixed solvent of ethylene carbonate and diethyl carbonate in a volume ratio of 1: 1) are placed in a pressure and heat resistant container, and the container is placed in a thermostatic bath at 150 ° C. and taken out after 1 hour. Further, the sample pieces are taken out from the pressure and heat resistant container, and the lengths in the MD direction and the TD direction are measured to measure the heat shrinkage rates in the respective directions, and the heat shrinkage rates in the MD direction and the heat shrinkage in the TD direction. The larger value of the rates was taken as the thermal shrinkage rate of the separator.

The porous membrane according to the non-aqueous secondary battery of Example 5 is the same as the separator according to the battery of Example 1 except that a strip-shaped sample piece having a size of 5 cm × 10 cm in any direction was produced. The heat shrinkage rate was measured by the method. Furthermore, the porous layer according to the non-aqueous secondary battery of Examples 6 and 7 is related to the battery of Example 1 except that a strip-shaped sample piece of 5 cm × 10 cm is produced in an integrated state with the electrode. The thermal shrinkage rate was measured by the same method as for a separator. In addition, about the porous layer which concerns on the non-aqueous secondary battery of Example 7, the larger one of what was formed in the positive electrode surface and what was formed in the negative electrode surface was made into the thermal contraction rate.

Further, the moisture content of the separators according to the non-aqueous secondary batteries of Examples 1 to 4 and Comparative Examples 1 and 2 and the porous membrane according to the non-aqueous secondary battery of Example 5 was measured by the above method.

Table 1 shows the evaluation results. In Table 1, the 180 ° peel strength between the porous layer and the porous resin film in the separator is simply referred to as “peel strength”, and the heat in the nonaqueous electrolyte solvent of the separator or porous layer is described. The shrinkage rate is simply referred to as “thermal shrinkage rate”.

As shown in Table 1, the separators or porous layers used in the nonaqueous secondary batteries of Examples 1 to 7 had a small heat shrinkage rate at 150 ° C. in a nonaqueous electrolyte solvent. That is, since these separators and porous layers are unlikely to shrink even when exposed to high temperatures in the presence of a non-aqueous electrolyte solvent in the battery, it is possible to constitute a non-aqueous secondary battery with excellent safety. I can say that. From the measurement results of the 180 ° peel strength between the porous layer and the porous resin film in the separators according to the nonaqueous secondary batteries of Examples 1 to 4, the nonaqueous secondary batteries of Examples 1 to 7 were used. It can be seen that the organic binder used in the separator or porous layer used in the above has a specific copolymer composition, and thus has a high adhesive force. Thus, it can be seen that even when exposed to a high temperature in a non-aqueous electrolyte solvent, the excellent adhesive force can be maintained well.

Furthermore, charge / discharge characteristics of the non-aqueous secondary batteries of Examples and Comparative Examples were evaluated by the following method. First, for each battery, constant current charging was performed until the battery voltage reached 4.2 V at a current value of 0.2 C, and then constant current-constant voltage charging for performing constant voltage charging at 4.2 V was performed. The total charging time until the end of charging was 15 hours. And the charge capacity at that time was measured. Next, each battery after charging was discharged at a discharge current of 0.2 C until the battery voltage reached 3.0 V, and the discharge capacity was measured. And about each battery, the ratio of the discharge capacity with respect to charge capacity was represented by the percentage, and charging efficiency was calculated | required.

As a result, in the batteries of Examples 1 to 7 and Comparative Example 1, the charging efficiency was almost 100%, and it was confirmed that the battery operated well. On the other hand, in the battery of Comparative Example 2, an organic binder having an inappropriate copolymer composition was used as the organic binder of the porous layer related to the separator, but the charging efficiency was low, and the moisture content of the separator was reduced by using the organic binder. Gas generation due to the increase was noticeable.

The present invention can be implemented in other forms as long as it does not depart from the spirit of the present invention. The embodiments disclosed in the present application are examples, and the present invention is not limited to these embodiments. The scope of the present invention is construed in preference to the description of the appended claims rather than the description of the above specification, and all modifications within the scope equivalent to the claims are construed in the scope of the claims. included.

The nonaqueous battery of the present invention can be applied to the same uses as conventionally known nonaqueous secondary batteries such as lithium secondary batteries and nonaqueous primary batteries.

1 Positive electrode 2 Negative electrode 3 Separator 4 Nonaqueous electrolyte

Claims

A porous layer for a non-aqueous battery comprising fine particles having an heat resistant temperature of 150 ° C. or higher and an organic binder,
Examples of the organic binder include a copolymer of an N-vinylcarboxylic acid amide represented by the following general formula (1) and an unsaturated carboxylic acid monomer represented by the following general formula (2):
The non-aqueous battery porous material, wherein a copolymerization ratio of the N-vinylcarboxylic acid amide and the unsaturated carboxylic acid monomer in the copolymer is 50:50 to 95: 5 by mass ratio layer.

[In the general formula (1), R 1 and R 2 each independently represent a hydrogen atom or a methyl group, and R 3 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms]

[In the general formula (2), R 4 represents a hydrogen atom, a methyl group or —COOM 2 , R 5 represents a hydrogen atom, a methyl group or —COOM 3 , and M 1 , M 2 and M 3 each independently represent A hydrogen atom, an alkali metal, an alkaline earth metal, an ammonium group or an organic amino group, and n is 0 or 1)
The porous layer for a non-aqueous battery according to claim 1, wherein the N-vinylcarboxylic amide represented by the general formula (1) is N-vinylacetamide.
The unsaturated carboxylic acid monomer represented by the general formula (2) is at least one selected from the group consisting of acrylic acid, methacrylic acid, acrylate, and methacrylate. Porous layer for non-aqueous battery.
The porous layer for a nonaqueous battery according to claim 3, wherein the unsaturated carboxylic acid monomer represented by the general formula (2) is an alkali metal salt of acrylic acid or an alkali metal methacrylate.
The porous layer for a non-aqueous battery according to any one of claims 1 to 4, wherein the copolymer has a molecular weight of 30,000 to 5,000,000.
The porous layer for a non-aqueous battery according to any one of claims 1 to 5, wherein the fine particles are fine particles of oxide or hydroxide.
The porous layer for a non-aqueous battery according to any one of claims 1 to 6, wherein the content of the organic binder is 0.5 to 10% by mass.
A separator for a non-aqueous battery, wherein the porous layer for a non-aqueous battery according to any one of claims 1 to 7 is formed on a porous resin film.
The separator for a non-aqueous battery according to claim 8, wherein the porous resin film is a polyolefin microporous film.
A nonaqueous battery electrode, wherein the nonaqueous battery porous layer according to any one of claims 1 to 7 is formed on an electrode mixture layer.
A non-aqueous battery comprising a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, wherein the separator is the separator for a non-aqueous battery according to claim 8 or 9.
A nonaqueous battery comprising a positive electrode, a negative electrode, and a nonaqueous electrolyte, wherein at least one of the positive electrode and the negative electrode is the electrode for a nonaqueous battery according to claim 10.