JP2001273895A - Nonaqueous electrolyte secondary battery and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery having a positive electrode which keeps elasticity without lowering its characteristics of oxidation resistance, electrolyte solubility resistance, etc. SOLUTION: LiNi1-XMXO2 (M shows at least one element selected from among Co, Al, Mn, Fe, Nb, Mg, B, F, and Y and the range of X is 0<=X<=0.5) is used for the positive active material 21a, 21b, 21c, and as a binding agent 22, use is made of a mix which is made by adding an organic acid to a fluorine containing polymer mix containing a polymer having rubber elasticity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery having high energy density and high reliability, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the performance and miniaturization of electronic devices such as video cameras and headphone stereos have been remarkable, and the demand for higher energy secondary batteries as power sources for these electronic devices has also increased. I have. Therefore, the development of a sealed battery using a material capable of occluding and releasing lithium, such as lithium metal, lithium alloy, or carbonaceous material, as a negative electrode material has been actively performed.

On the other hand, the positive electrode material constituting the positive electrode is composed of a positive electrode active material, a conductive agent and a binder. In many cases, a lithium cobalt composite oxide, a lithium nickel composite oxide, or the like is used as the positive electrode active material. Among them, lithium nickel composite oxides are attracting attention as positive electrode active materials for future high-capacity nonaqueous electrolyte secondary batteries because of their reversible capacity per unit weight.

Fluororesins such as polyvinylidene fluoride and polytetrafluoroethylene are widely used as binders from the viewpoints of oxidation resistance, electrolytic solution resistance and the like. Polyvinylidene fluoride is often used in many cases.

[0005]

When using the fluorine-containing polymer having no rubber elasticity [0006] The (polyvinylidene fluoride) alone as a binder, use a positive electrode active material composed of LiNi _1-X M _X O ₂ The cross-linking reaction progresses due to the reaction of the positive electrode with the positive electrode active material and the conductive additive, and the positive electrode becomes hard and brittle as a positive electrode. In the future, it is considered that it is necessary to apply a larger amount of active material per unit area in a battery in which a higher capacity is desired in the future.

In particular, in a battery using the folding winding method, the curvature of the folded portion is larger than that of a cylindrical battery, and a large force is concentrated on the folded portion at the time of winding, so that the electrode is easily cut. As a result, the production yield is greatly reduced.

[0007] The fluorine-containing polymer containing the rubber material - the positive electrode (the (vinylidene fluoride to hexa fluoro ethylene) copolymer, _etc.), using the positive electrode active material composed of _{LiNi 1-X} M _{X O 2} When used as a binder, the elasticity of the rubber improves the flexibility of the electrode and contributes to the improvement of the yield. This effect increases as the amount of the rubber substance increases.

The present invention has been made based on these circumstances, and a non-aqueous electrolyte secondary battery having a positive electrode maintaining flexibility without deteriorating oxidation resistance, electrolyte resistance, and the like, It is intended to provide a manufacturing method.

[0009]

According to the present invention, in a non-aqueous electrolyte secondary battery in which an electrode group in which a positive electrode and a negative electrode are opposed to each other with a separator interposed therebetween in a container, the positive electrode forms a supporting base. _{has, LiNi 1-X M X O} 2 ( however, M is Co, Al, Mn, Cr, Fe, Nb, Mg, B, F,
At least one element selected from the elements of Y, and x is in the range of 0 ≦ x ≦ 0.5), a binder made of a fluorine-containing polymer containing a rubber substance, a conduction aid, and an organic solvent. And a nonaqueous electrolyte secondary battery formed by applying a mixture containing an organic acid to the support base.

According to the present invention, the binder is made of a fluorine-containing polymer containing a rubber substance, and has a size of a motility-constrained crosslinked region in a heterogeneous structure. A nonaqueous electrolyte secondary battery controlled by addition of an acid.

According to the present invention, there is provided a non-aqueous electrolyte secondary battery, wherein the organic acid is maleic anhydride.

Further, according to the present invention, in a method for manufacturing a nonaqueous electrolyte secondary battery in which an electrode group in which a positive electrode and a negative electrode are opposed to each other via a separator in a container is provided,
A support _{base, LiNi 1-X M X O} 2 ( however, M
Are Co, Al, Mn, Cr, Fe, Nb, Mg, B,
At least one element selected from the elements of F and Y, and the range of x is 0 ≦ x ≦ 0.5), a positive electrode active material, a binder made of a fluorine-containing polymer containing a rubber substance, a conduction aid,
A method for producing a non-aqueous electrolyte secondary battery, comprising: a step of applying a mixture containing an organic solvent and an organic acid to the support base; and a step of drying the mixture.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of a nonaqueous electrolyte secondary battery according to the present invention will be described with reference to the drawings, taking a cylindrical sealed secondary battery as an example. The shape and the shape of the thin battery can be used. In addition,
The cylindrical shape means that the shape when the outer can is cut at the surface including the power generating element is a circle or a shape similar to the circle.

FIG. 1 is a partial longitudinal sectional view showing a non-aqueous electrolyte secondary battery according to the present invention, for example, a cylindrical sealed lithium ion secondary battery.

For example, a bottomed cylindrical container 1 made of stainless steel as an exterior body has an insulator 2 disposed at the bottom. The electrode group 3 is housed in the container 1. Electrode group 3
Has a structure in which a strip formed by laminating the positive electrode 4, the separator 5, the negative electrode 6, and the separator 5 is spirally wound so that the separator 5 is located outside.

The container 1 contains an electrolytic solution.
The insulating paper 7 whose center is opened is disposed above the electrode group 3 in the container 1. The insulating sealing plate 8 is arranged in the upper opening of the container 1, and the sealing plate 8 is fixed to the container 1 by caulking the vicinity of the upper opening inward. The positive electrode terminal 9 is fitted in the center of the insulating sealing plate 8. One end of the positive electrode lead 10 is connected to the positive electrode 4, and the other end is connected to the positive electrode terminal 9. The negative electrode 6 is connected to the container 1 as a negative electrode terminal via a negative electrode lead (not shown).

The positive electrode 7 comprises a positive electrode active material,
It is composed of a conductive agent, a binder, an organic solvent and the like.

FIG. 2 (a) is a schematic diagram showing the relationship between the positive electrode active material and the binder, and FIG. 2 (b) shows the structure of the binder and its rubber elasticity (elasticity on rubber). This will be described with reference to the schematic diagram of the microstructure of the rubber substance shown.

As shown in FIG. 2A, the positive electrode active material 21
Adjacent parts a, 21b, and 21c are mutually connected by a binder 22 that is a rubber elastic substance.

In general, the microstructure of a rubber material is known as a non-uniform structure model. As shown in FIG. 2B, in this structural model, a non-crosslinked rubber molecular chain region (A-region) 23 having high mobility, a collective crosslinked region (B-region) 24 having restricted mobility, and A The quasi-glass state region (C-region) 25 at the interface between the-region and the B-region is formed from three types of regions.

When a nickel-based composite oxide is used as a positive electrode active material, its basicity promotes crosslinking of a fluorine-containing polymer containing a rubber material, thereby obtaining a vulcanizing effect and exhibiting rubber elasticity. The B-region 24 is formed therein,
When the B-region 24 is widely dispersed in the binder 22 with the minimum size, the most effective flexibility can be obtained without impairing the cold resistance, solvent resistance and heat resistance.

In the present invention, the balance with the basicity of the nickel composite oxide is controlled by adding an organic acid, the size of the B-region 24 is reduced and widely dispersed, and the content of the rubber substance is reduced. Flexibility is efficiently realized without lowering oxidation resistance, electrolyte resistance, cold resistance, heat resistance and the like.

A lithium nickel used as a positive electrode active material
Kel composite oxide is LiNi_1-XM _XO₂(M is Co,
Elements of Al, Mn, Cr, Fe, Nb, Mg, B, F, Y
Indicates at least one element selected from the primes and the range of x
Is represented by 0 ≦ x ≦ 0.5).

The conductive additive contributes to the improvement of the electrical conductivity between the positive electrode active material and between the positive electrode active material and the electrode substrate, and is made of carbon black, graphite fine powder, fibrous carbonaceous material or nickel. , A metal fine powder such as aluminum, or a fiber is used.

The fluorine-containing polymer containing a rubber substance used for the binder in the present invention includes polyvinylidene fluoride, polytetrafluoroethylene or a copolymer of these two compounds, such as hexafluoropropylene, silicone rubber, butyl rubber, Chlorotrifluoroethylene rubber, ethylene propylene rubber, or a mixture of two or more of these rubbers is used in which 0.1 to 25% of a monomer ratio is copolymerized. In particular, these polymers are particularly effective when partially modified with carboxylic acid.

The above binder is dispersed in an organic solvent such as N-methylpyrrolidinone or the like, and then added to maleic acid, oxalic acid, malonic acid, formic acid, citric acid, acetic acid, lactic acid, pyruvic acid, propionic acid, citraconic acid, butyric acid. The organic acid and the anhydride thereof are added to the positive electrode active material in an amount of 5 to 10,000 ppm, more preferably 10 to 5000 ppm, and even more preferably 50 to 2500 ppm.

[0027] in the mix, such as the _{above, LiNi 1-X M} X
O ₂ (M is Co, Al, Mn, Cr, Fe, Nb, M
and at least one element selected from the elements of g, B, F, and Y. The range of x is 0 ≦ x ≦ 0.5). A cathode active material represented by the formula and a conductive auxiliary such as carbon black are dispersed therein. .

This mixture is uniformly applied on a metal supporting substrate such as Al, Cu, and stainless steel, and the organic solvent is removed to form a positive electrode.

In the positive electrode thus completed, the crystallinity of the binder is reduced, and the flexibility of the electrode is uniformly improved. In addition, since the A-region responsible for rubber elasticity is dispersed throughout the electrode, it is generated as the charge / discharge cycle progresses due to the change in the shape of the particles during charging / discharging of the positive electrode active material, which is unique to lithium nickel composite oxide. Of the discharge capacity can be suppressed.

Next, the specifications and manufacturing method of the above-described positive electrode 4, separator 5, negative electrode 6, and non-aqueous electrolyte will be described. The reference numerals used in FIG. 1 are referred to.

(1) Positive electrode The positive electrode 4 is manufactured by drying and pressing the above-mentioned positive electrode 4 to form a strip electrode. The mixing ratio of the positive electrode active material, the conductive agent and the binder is preferably in the range of 80 to 95% by weight of the positive electrode active material, 3 to 20% by weight of the conductive agent, and 2 to 7% by weight of the binder.

(2) Separator As the separator 5, for example, a synthetic resin nonwoven fabric, a polyethylene porous film, a polypropylene porous film, or the like can be used.

(3) Negative Electrode The negative electrode 6 is prepared by suspending a conductive agent and a binder in a negative electrode active material in an appropriate solvent, applying the suspension to a current collector such as a copper foil, drying, and drying.
It is manufactured by pressing to form a band. As the negative electrode active material, a material that stores and releases an alkali metal can be used. For example, carbonaceous materials, chalcogen compounds, light metals, and the like can be used. Above all, a negative electrode containing a carbonaceous substance or a chalcogen compound that occludes / releases an alkali metal is preferable because battery characteristics such as a battery's charge / discharge cycle life are improved.

As the carbonaceous material for absorbing and releasing lithium ions, for example, coke, carbon fiber, pyrolysis gas phase carbonaceous material, graphite, fired resin, mesophase pitch-based carbon fiber, fired mesophase spherical carbon, or the like is used. be able to. Among them, mesophase spherical carbon graphitized at 2500 ° C. or higher is preferable because the electrode capacity is increased.

As chalcogen compounds that occlude and release lithium ions, titanium disulfide, molybdenum disulfide,
Niobium selenide or the like can be used. When such a chalcogen compound is used for the negative electrode, although the voltage of the battery drops, the capacity of the negative electrode increases, so that the capacity of the secondary battery is improved. Further, since the negative electrode has a high diffusion rate of lithium ions, rapid charge and discharge performance of the battery is improved.

As the light metal, aluminum, aluminum alloy, magnesium alloy, lithium metal, lithium alloy and the like are used.

As the current collector, for example, a copper foil, a nickel foil or the like is used, and in consideration of electrochemical stability and flexibility at the time of winding, a copper foil is most preferable. In this case, the thickness of the copper foil is preferably 8 μm or more and 40 μm or less.

As the conductive agent, for example, acetylene black, carbon black, graphite and the like can be used.

As the binder, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PV
dF), a fluorine-based rubber, an ethylene-propylene diene copolymer (EPDM), a styrene-butadiene rubber (SBR), or the like can be used.

The mixing ratio of the negative electrode active material, the conductive agent and the binder is preferably in the range of 80 to 98% by weight of the negative electrode active material and 2 to 20% by weight of the binder.

For the negative electrode 6, for example, acetylene black, carbon black, graphite or the like can be used as a conductive agent.

Examples of the binder include polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PV
dF), fluorinated rubber, styrene-butadiene rubber (S
BR), carboxymethylcellulose (CMC) and the like can be used.

The mixing ratio of the negative electrode active material, the conductive agent and the binder is preferably in the range of 70 to 95% by weight of the negative electrode active material, 0 to 25% by weight of the conductive agent, and 2 to 10% by weight of the binder. .

(4) Non-Aqueous Electrolyte The non-aqueous electrolyte is a liquid electrolyte prepared by dissolving the electrolyte in a non-aqueous solvent, or a polymer gel electrolyte in which a polymer material contains a non-aqueous solvent and an electrolyte. Alternatively, a polymer solid electrolyte containing only an electrolyte or an inorganic solid electrolyte having lithium ion conductivity can be used.

As the liquid electrolyte, a known non-aqueous solvent obtained by dissolving a lithium salt as an electrolyte in a non-aqueous solvent of a lithium battery can be used, and a cyclic carbonate such as ethylene carbonate (EC) or propylene carbonate (PC) can be used. Further, it is preferable to use a non-aqueous solvent mainly composed of a mixed solvent of a cyclic carbonate and a non-aqueous solvent having a lower viscosity than the cyclic carbonate (hereinafter referred to as a second solvent).

Examples of the second solvent include chain carbonates such as dimethyl carbonate, methyl ethyl carbonate and diethyl carbonate, γ-butyrolactone, acetonitrile, methyl propionate, ethyl propionate, and cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran. And dimethoxyethane, diethoxyethane and the like can be used as a chain ether.

As the electrolyte, an alkali salt can be used, and in particular, a lithium salt can be used.
As a lithium salt, lithium hexafluorophosphate (LiPF
₆ ), lithium tetrafluoride (LiBF ₄ ), lithium arsenide hexafluoride (LiAsF ₆ ), lithium perchlorate (LiCl
0 _4), trifluoroacetic meth lithium sulfonate (LiC
F ₃ S0 ₃₎ or the like can be used. Particularly, lithium hexafluorophosphate (LiPF ₆ ) and lithium tetrafluoroborate (LiBF ₄ ) are preferable. The amount of the electrolyte dissolved in the nonaqueous solvent is preferably 0.1 to 5.0 mol / l.

As a gel electrolyte, a solvent and an electrolyte are dissolved in a polymer material to form a gel. Examples of the polymer material include polyacrylonitrile, polyacrylate, polyvinylidene fluoride (PVdF), and polyethylene oxide (PECO). A polymer of a monomer or a copolymer with another monomer can be used.

The solid electrolyte is obtained by dissolving the electrolyte in a polymer material and solidifying it. Polymer materials include polyacrylonitrile, polyvinylidene fluoride (PVd
F), a polymer of a monomer such as polyethylene oxide (PEO), or a copolymer with another monomer can be used. Further, as the inorganic solid electrolyte, a ceramic material containing lithium can be used. Above all, Li
_{3 N,} etc. _{Li 3 PO 4 -Li 2 S-} SiS 1 glass can be used.

Although the example in which the present invention is applied to a cylindrical non-aqueous electrolyte secondary battery has been described with reference to FIG. 1, the present invention can be similarly applied to a rectangular non-aqueous electrolyte secondary battery and a thin lithium battery.

The electrode group accommodated in the container of the battery is not limited to the spiral type, but may be a configuration in which a plurality of positive electrodes, separators and negative electrodes are laminated in this order.

Next, examples of the production of the positive electrode of the present invention and comparative examples will be described.

(Example 1) Lithium-nickel composite oxide Li _X NiO ₂ as a positive electrode active material, carbon powder as a conductive agent, poly (vinylidene fluoride) and hexane as a binder 93: 7 monomer The fluorinated polymer copolymerized at a specific ratio and maleic anhydride were mixed at a weight ratio of 100: 6: 3: 0.1, respectively. After making a paste with N-methylpyrrolidinone, which is a solvent, the paste was applied on an aluminum support substrate so that the coating amount of the electrode mixture was uniform at 200 g / m ² , and dried. After pressing with a roll press so that the bulk density becomes 2.93 g / cm ³ ,
It was cut out to 3 cm x 6 cm.

Example 2 LiNi was used as the positive electrode active material.
_0.8 Co _0.2 O ₂ was used, and a fluorine-containing polymer in which silicone rubber was blended at 50:50 with polyvinylidene fluoride as a binder was used. These and malonic anhydride were mixed at a weight ratio of 100: 3: 1. Otherwise, an electrode was produced in the same manner as in (Example 1).

Example 3 LiNi was used as the positive electrode active material.
_0.95 Al _0.05 O ₂ was used, and a fluorine-containing polymer obtained by blending 10% of butyl rubber with a copolymer of poly (vinylidene fluoride) and polytetrafluoroethylene at a monomer ratio of 3: 1 was used as a binder. These and citric acid, respectively
Using a weight ratio of 100: 5: 0.00l, an electrode was produced in the same manner as in (Example 1).

Example 4 LiNi was used as the positive electrode active material.
_0.5 Al _0.08 Co _0.42 O ₂ was used, and chlorotrifluoropropylene rubber was added to a copolymer of polyvinylidene fluoride and polytetrafluoroethylene at a monomer ratio of 100: 0.1 as a binder. 1% copolymerized fluoropolymer was used. Each of these and acetic acid were added in a weight ratio of 100:
5: 0.0005. Other than that, an electrode was produced in the same manner as in (Example 1).

Example 5 LiNi was used as the positive electrode active material.
_0.7 Nb _0.3 O ₂ was used, and a fluoropolymer obtained by copolymerizing 12% of ethylene propylene rubber with polyvinylidene fluoride as a binder was used. These and oxalic acid were used in a weight ratio of 100: 5: 0.1, respectively. Other than that, an electrode was produced in the same manner as in (Example 1).

Example 6 LiNi was used as the positive electrode active material.
_0.8 Mn _0.2 O ₂ was used, and a fluoropolymer obtained by copolymerizing 5% of hexafluoropropylene and 12% of chlorotrifluoropropylene with polyvinylidene fluoride as a binder was used. These and lactic acid are added in a weight ratio of 100: 2, respectively.
0: 1. 0 was used. Other than that, an electrode was produced in the same manner as in (Example 1).

Example 7 LiNi was used as the positive electrode active material.
Using _0.6 Fe _0.4 0 _2, with silicone rubber 6% blended polymer material of ethylene-propylene rubber in a fluorine-containing polymer obtained by copolymerizing 1% polyvinylidene fluoride binder. These and pyruvic acid were used in a weight ratio of 100: 12: 0.5, respectively, and an electrode was produced in the same manner as in (Example 1) except for these.

Example 8 LiNi was used as the positive electrode active material.
_{Using 0.5} Cr _0.5 O ₂ , a polymer material in which 25% of butyl rubber was blended with a fluorine-containing polymer obtained by copolymerizing 25% of hexafluoropropylene with polyvinylidene fluoride as a binder was used. These and propionic acid, respectively,
Used at a weight ratio of 100: 12: 0.2. Other than that, an electrode was produced in the same manner as in (Example 1).

Example 9 LiNi _0.6 was used as the positive electrode active material.
Co _0.1 Nb _0.2 O ₂ was used, and a polymer material in which 25% of hexafluoropropylene was copolymerized with poly (vinylidene fluoride) was used as a binder. These, propionic acid and citraconic acid were added in a weight ratio of 100: 2: 0. 1: 0.
4, and an electrode was produced in the same manner as in (Example 1).

Example 10 LiNi was used as the positive electrode active material.
_0.6 Co _0.25 Al _0.15 O ₂ was used, and a polymer material obtained by copolymerizing 25% of hexafluoropropylene with polyvinylidene fluoride as a binder was used. These and butyric acid. Formic acid in a weight ratio of 100: 2: 0.9: 0.1
An electrode was produced in the same manner as in (Example 1).

(Example 11) LiNi was used as the positive electrode active material.
_{Using 0.7} Mg _0.2 g Y _0.1 O ₂ , 15% of hexafluoropropylene for polyvinylidene fluoride as a binder
Was used. These and maleic anhydride were used in a weight ratio of 100: 7: 0.03, respectively. Other than that, an electrode was produced in the same manner as in (Example 1).

Example 12 LiNi _0.7 B _0.15
F _0.15 O ₂ was used, and a polymer material obtained by copolymerizing 7% of hexafluoropropylene with polyvinylidene fluoride as a binder was used. These and maleic anhydride were used in a weight ratio of 100: 10: 0.5, respectively. Other than that, an electrode was produced in the same manner as in (Example 1).

Comparative Example 1 A mixture was prepared in the same manner as in Example 1 except that a single polyvinylidene fluoride was used as a binder.
Dispersion and coating were performed to produce an electrode.

(Comparative Example 2) An electrode was prepared by mixing, dispersing and coating in the same manner as in (Example 1) except that maleic anhydride was not added.

Comparative Example 3 Polyvinylidene fluoride copolymerized with 35% hexafluoropropylene was used as a binder, and the mixture was mixed and mixed in the same manner as in (Example 1) except that maleic anhydride was not added. Dispersion and coating were performed to produce an electrode.

Peeling off the electrodes produced by the above-described methods of (Example 1) to (Example 10), (Comparative Example 1), (Comparative Example 2) and (Comparative Example 3) from the electrode supporting base. The strength was measured. The measuring method is described below.

In this measuring method, an adhesive tape was attached to the electrode, a 500 g weight was connected to the adhesive tape, and the time required for peeling off the coated portion from the electrode supporting base in the long side direction was measured three times. The measurements were taken and the average was taken. Table 1 shows the measurement results when the average time required for the electrode in this case (Comparative Example 1) was “1”.

[Table 1] The above electrodes were evaluated for adhesion and immersed in an ethylene carbonate solution (60 ° C.) (for 7 days), and the state of the electrode mixture layer was evaluated for the presence or absence of cracks and peeling.

The adhesion was evaluated by wrapping a metal cylinder having a constant diameter so that the electrode support base was inside and the electrode mixture layer was outside, and the electrode was pulled out while holding one end of the electrode. The state of the electrode mixture layer at that time was evaluated for the presence or absence of cracks and peeling. The temperature at that time was -20 ° C.
And 23 ° C.

Table 2 shows the results of the evaluation.

[Table 2]<Judgment> ：: No change Δ: Slight crack generation X: Large crack, or disconnection and peeling of electrode As described above, in the present invention, as the positive electrode active material,
LiNi_1-XM_XO ₂(M is Co, Al, Mn, C
selected from the elements r, Fe, Nb, Mg, B, F and Y
It indicates at least one type, and the range of x is 0 ≦ x ≦
0.5) containing a polymer having rubber elasticity
In a mixture consisting of a nitrogen polymer, a conductive assistant, and an organic solvent,
For non-aqueous electrolyte secondary batteries with a mixture containing acid
Oxidation resistance, electrolyte resistance, etc.
A highly flexible positive electrode without lowering the
Obtainable. In addition, a non-electrode using the positive electrode of the present invention.
The water electrolyte secondary battery can obtain good bending performance.

[0072]

According to the present invention, there can be obtained a non-aqueous electrolyte secondary battery having a positive electrode having excellent oxidation resistance and electrolytic solution resistance and having good flexibility and good elasticity.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view of a cylindrical nonaqueous electrolyte secondary battery according to an embodiment of the present invention.

FIG. 2A is a schematic diagram showing the relationship between the positive electrode active material of the present invention and a binder, and FIG. 2B is a schematic diagram showing the structure of the binder and the microstructure of the rubber material.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... container, 3 ... electrode group, 4 ... positive electrode, 5 ... separator, 6
... negative electrode, 21a, 21b, 21c ... positive electrode active material, 22 ...
Binder, 23 ... A-region, 24 ... B-region, 25 ... C-
region

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H029 AJ14 AK03 AL04 AL06 AM02 BJ02 BJ14 CJ02 CJ08 CJ22 DJ08 EJ12 HJ02 5H050 AA19 CA08 CB05 CB07 DA11 EA24 GA02 GA10 GA22 HA02

Claims (4)

[Claims] 1. A nonaqueous electrolyte secondary battery in which an electrode group in which a positive electrode and a negative electrode are opposed to each other with a separator interposed therebetween is contained in a container, wherein the positive electrode has a supporting base, and a LiNi _1-X M
_X O ₂ (where M is Co, Al, Mn, Cr, Fe,
At least one selected from the elements of Nb, Mg, B, F, and Y, and the range of x is 0 ≦ x ≦ 0.5), a positive electrode active material, and a binding made of a fluorine-containing polymer containing a rubber material. A non-aqueous electrolyte secondary battery formed by applying a mixture obtained by adding an agent, a conduction aid, an organic solvent and an organic acid to the support base. 2. The binder according to claim 1, wherein the binder is composed of a fluoropolymer containing a rubber material, and the size of the motility-bound crosslinked region in the heterogeneous structure is controlled by adding an organic acid. The non-aqueous electrolyte secondary battery according to claim 1, wherein: 3. The non-aqueous electrolyte secondary battery according to claim 1, wherein the organic acid is maleic anhydride. 4. A method for manufacturing a non-aqueous electrolyte secondary battery in which an electrode group in which a positive electrode and a negative electrode are opposed to each other via a separator in a container is provided, wherein the positive electrode has a supporting base,
_{iNi 1-X M X O 2} ( however, M is Co, Al, M
n, at least one selected from elements of Cr, Fe, Nb, Mg, B, F, and Y, and the range of x is 0 ≦ x ≦
0.5) a positive electrode active material comprising: a binder comprising a fluorine-containing polymer containing a rubber substance; a conduction aid; a mixture obtained by adding an organic solvent and an organic acid to the support base;
A method for producing a non-aqueous electrolyte secondary battery, wherein the method is formed by a drying step.