JP2000323174A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the degradation or the like of charge-discharge capacity and to improve a high-rate discharge characteristic and a low-temperature characteristic by providing a positive electrode and/or a negative electrode of which surface has a specific roughness. SOLUTION: The center line average roughness of the surface of a positive electrode and/or a negative electrode is set to 5.0 μm or more. When the roughness is less than 5.0 μm, the safety of a battery can not be improved. In order to process the surface of the electrode to this roughness, a brushing method and excimer laser irradiation are particularly recommended. A nonaqueous electrolyte comprises an organic electrolytic solution comprising an organic solvent, anions and cations, and a porous high-polymer electrolyte swelled by the electrolytic solution. The negative electrode can contain two or more kinds of negative electrode active materials different in material and/or shape. Al and hard-to-graphatize carbon, or SnO, Li and easy-to-graphatize carbon can be offered as mixtures different in material. Graphatized MCMB, scale-like natural graphite and the like can be offered as mixtures different in shape.

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.

[0002]

2. Description of the Related Art In recent years, with the development of electronic devices, the appearance of new high-performance secondary batteries is expected. Various secondary batteries are used as power supplies for electronic devices. Recently, high-voltage batteries of 3 V or more using non-aqueous electrolytes have been manufactured, and a typical example thereof is a so-called lithium secondary battery. There is a battery.

[0003] Secondary batteries using metallic lithium for the negative electrode are disadvantageous in that a short circuit is apt to occur due to the precipitation of metallic lithium dendrite, and the life is short. In addition, safety is high due to the high reactivity of metallic lithium. It is difficult to secure. To this end, a so-called lithium ion secondary battery has been devised which uses a carbon-based material such as graphite or carbon instead of metallic lithium.

In a lithium ion secondary battery, the utilization rate of an active material is limited due to safety issues. Therefore, the lithium ion secondary battery has a higher practical energy density than expected from the chargeable / dischargeable capacity of the active material. There is a problem that the above energy density is reduced.

[0005] Carbon-based negative electrode materials such as graphite and carbon used for the negative electrode include short fibers, spheres, flakes, and the like.
Various materials such as irregular shapes are used, but most of them are fine particles and therefore bulky. For this reason, when such bulky particles are used, it is common practice to compress the electrode by a roll press or the like in order to improve the energy density per volume of the electrode. Such processing is also performed on the positive electrode, and improvement in energy density per volume by compression processing is essential in battery production.

As a method for processing a solid surface, there is a method using a laser. This laser processing method includes a thermal processing method and a photochemical processing method. The thermal processing method, for example, irradiates an object such as metal with a laser, and generates heat by laser absorption,
Fusing or welding. On the other hand, the photochemical processing method irradiates an object such as an organic substance, which has strong absorption in the ultraviolet region, with ultraviolet rays, and cuts a bond chain of a molecule constituting the object.

An excimer laser is one such laser. This is the light emitted when the excited state molecules fall to the ground state. XeF, XeCl, XeBr, Kr are used as medium gases used for emitting this light.
F, KrCl, ArF, ArCl, F _{2 and the} like are used. These medium gases emit a laser with a wavelength of 350-157 nm. Because these short-wavelength lasers have very high energy, irradiating an object with light of such a wavelength breaks the chemical bonds of the molecules of the object, and as a result, the object is decomposed at the atomic level. I do. Such processing methods have hitherto been used for etching semiconductors.

[0008]

However, when compression processing with a high degree of processing is performed, the energy density per volume is greatly improved, but the processed surface, that is, the electrode surface is over-crushed and the electrode mixture particles are deformed. Is seen. In a battery using such an electrode, resistance to ionic conductivity increases on the electrode surface, so that when charging and discharging are performed at a high current density, there is a problem that polarization is large and the battery voltage is greatly reduced.

In particular, in the case of a negative electrode containing two or more types of active materials having different shapes and properties, the porosity of the electrode surface is liable to decrease when compression processing such as roll pressing is performed. In a battery manufactured using such an electrode, if lithium ions are not easily diffused or migrated on the surface of the negative electrode, a phenomenon of electrodeposition of metallic lithium during charging appears. This electrodeposition is particularly effective when a large current flows, such as rapid charging,
This is remarkably observed at a low temperature of 0 ° C. or lower at which the characteristics of the electrolyte deteriorate. Electrodeposition of metallic lithium, if it occurs on the electrode surface, causes a short circuit.

In particular, when the battery is designed to charge not only the carbon-based negative electrode active material but also the electrodeposited electrode, if the electrode surface is over-crushed, lithium has a priority over the electrode surface. There has been a problem that the electrodeposition is caused by the electrodeposition and the safety such as the occurrence of short circuit is reduced.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has an electrode surface having a center line average roughness (R).
_a ) The first invention is a nonaqueous electrolyte secondary battery including a positive electrode and / or a negative electrode having a size of 5.0 μm or more.

According to the first invention, an ion-conductive porous polymer electrolyte is disposed between a positive electrode and a negative electrode, and at least one of the positive electrode and the negative electrode contains an ion-conductive porous polymer. The second invention is a non-aqueous electrolyte secondary battery.

According to the first or second invention, the nonaqueous electrolyte secondary battery is characterized in that the negative electrode contains two or more types of negative electrode active materials having different materials and / or shapes. This is the third invention.

[0014]

The non-aqueous electrolyte secondary battery according to the present invention embodiments of the Invention, the center line average roughness of the positive electrode and / or negative electrode surface and 5.0MyumR _a more.

The center line average roughness in the present invention is defined by JI
This is based on SB0601, and is briefly described below. The center line average roughness is obtained by extracting a portion of the measured length L from the roughness curve in the direction of the center line, setting the center line of the extracted portion as the X axis, the longitudinal magnification direction as the Y axis, and defining the roughness curve as y. = F (x) means a value obtained by the following equation expressed in micrometers (μm).

[0016]

(Equation 1) When the center line average roughness (R _a ) is 12.5 μm or less, the measurement length L is 2.5 mm or more. However, when _Ra is 12.
If it exceeds 5 μm and is 100 μm or less, the measurement length L is set to 7.
5 mm or more. The cut-off value follows the JIS standard,
0.8 mm. The cut-off value conforms to the stipulation in the JIS standard. That is, when the roughness curve is obtained, the cutoff value of the roughness curve is such that the attenuation rate is -12 dB / oc.
When a high-pass filter of t is used, the wavelength corresponds to a frequency at which the gain becomes 75%.

In the present invention, the center line average roughness is preferably at least 5.0 μm, more preferably at least 8.0 μm, and most preferably at least 10 μm. Further, when the thickness of the electrode is t μm, _Ra / t
Is preferably at least 0.005, more preferably at least 0.015, even more preferably at least 0.045.

When the center line average roughness of the electrode surface is smaller than 5.0 μm, the effect is small for improving the safety of the battery. When the center line average roughness is 5.0 μm or more, a highly safe battery can be obtained. From the viewpoint of safety, the upper limit of the center line average roughness does not need to be particularly limited. In order to increase the roughness, it is necessary to increase the number of times of laser processing, and it takes a long time to perform the processing.

In terms of battery safety, an electrode plate having a center line average roughness of 5.0 μm or more is particularly effective in the case of a negative electrode plate, but is also effective in the case of a positive electrode plate. Needless to say.

As a method for processing the electrode surface to a preferable center line average roughness, brushing, ion milling,
Examples include plasma irradiation, excimer laser irradiation, irradiation with an ultraviolet lamp, infrared irradiation, X-ray irradiation, and dry or wet chemical etching. Among them, a brushing method and excimer laser irradiation are preferred.

The brushing method is the simplest and cheapest method of rubbing with a brush. On the other hand, since excimer laser irradiation is a non-contact processing method, the active material is not crushed by processing by laser irradiation.
The pores of the electrode are preserved and the porosity does not decrease. In particular, when the electrode is subjected to compression processing by a roll press or the like and then processed to a preferable center line average roughness by the above processing method, a more preferable effect is obtained. That is, the electrode that has been subjected to compression processing such as a roll press decreases the porosity due to crushing of the active material particles on the surface, and the retention of the electrolyte decreases, so that the lithium ion conductivity decreases. Conceivable. Since such crushing of the active material particles is remarkably observed on the electrode surface, when the active material particles on the electrode surface are partially peeled off, the conductivity of lithium ions can be improved. That is, when the electrode after compression processing is processed to have a preferable center line roughness, the porosity of the surface can be improved, and more electrolyte can be contained in the pores. As a result, The diffusion characteristics of lithium ions can be improved, and charging and discharging at a high current density can be performed.

The non-aqueous electrolyte in the present invention comprises an organic electrolyte comprising an organic solvent, an anion and a cation, and a porous polymer electrolyte swollen with the organic electrolyte.

In the porous ion-conductive polymer electrolyte, the polymer portion exhibits ion conductivity. As the polymer material, lithium ions can be obtained by swelling in a non-aqueous electrolyte to form a gel and lithium ion conductivity can be obtained, or lithium ions can be transferred without swelling by a non-aqueous electrolyte such as polyethylene oxide. Possible polymers are used.

Specifically, polyethers such as polyethylene oxide and polypropylene oxide, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene chloride, polymethyl methacrylate, polyethylene terephthalate, polytetrafluoroethylene, polyhexafluoropropylene, polymethyl Acrylate, polyvinyl alcohol, polymethacrylonitrile, polyvinyl acetate, polyvinylpyrrolidone, polyethyleneimine, polybutadiene, polystyrene, polyisoprene, and derivatives thereof may be used alone or in combination. Further, a polymer obtained by copolymerizing a plurality of monomers constituting the polymer may be used.

Further, since the lithium ion conductive polymer electrolyte used in the non-aqueous electrolyte secondary battery according to the present invention is porous, lithium ions can be rapidly formed in the free organic electrolyte contained in the pores. Unlike conventional batteries using a lithium ion conductive polymer electrolyte having no communication hole, practical charge / discharge performance as a secondary battery can be obtained.

Examples of the method for perforating the ion-conductive polymer include a stretching method, a solvent removing method, and a needle sticking method, and a combination thereof.

The above-mentioned stretching method is a method in which after the above-mentioned polymer is synthesized, a uniaxial or biaxial tensile stress is applied to make the polymer porous.

The above-mentioned solvent removal method means that a polymer solution in which the above polymer is dissolved in a solvent (A) is dissolved in a solvent (B) which is insoluble in the polymer and compatible with the solvent (A). The solvent of the polymer solution is removed by immersion in the solvent, whereby the portion from which the solvent has been removed becomes a hole, and the polymer is solidified to obtain a porous polymer.

The above-mentioned needle piercing method is a method of mechanically piercing a polymer with a sharp fine line or the like at the tip.

As the solvent (A), n-methyl-
It can be selected from 2-pyrrolidone (NMP), N, N-dimethylformamide, formamide, N-methylformamide, dimethylsulfoxide, acetone, acetylacetone and the like. The solvent (B) which may be used by mixing a plurality of them can be selected from water, ethanol, methanol, isopropyl alcohol and the like. Also,
These may be used in combination. Examples of the organic solvent constituting the organic electrolyte include, for example, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, sulfolane, dimethyl sulfoxide, acetonitrile, dimethylformamide, dimethylacetamide, and trimethyl phosphate. , Triethyl phosphate, tributoxyethyl phosphate,
Polar solvents such as 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane, and methyl acetate, and mixtures thereof may be used.

The cations constituting the organic electrolyte include H ⁺ , Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ca ²⁺ , Zn
²⁺ and Al ³⁺ can be selected. Particularly, Li ⁺ is preferable. Also, a plurality of these may be used.

The anions constituting the organic electrolyte include PF ₆ ⁻ , BF ₄ ⁻ , AsF ₆ ⁻ , ClO ₄ ⁻ , SC
^{N -, I -, Cl -} , Br -, CF 3 SO 3 -, CF 3 CO 2 -,
(CF ₃ SO ₂ ) ₂ N ⁻ . Further, a plurality of these may be used. In particular, PF ₆ ^-, C
lO ₄ ^- is preferred.

For the purpose of improving the charge / discharge characteristics, safety, life characteristics, storage characteristics, etc., other compounds may be added to the non-aqueous electrolyte. For example, pyridine, pyrrole, crown ether, alkyl ether, triethanolamine, ethylenediamine, polyethylene glycol, CO
₂ , HF and the like. Further, a plurality of these may be used.

The negative electrode active material used in the present invention includes:
There are carbon materials, alloys, oxides, oxyhydroxides, sulfates, carbides, nitrides and the like.

As the above-mentioned carbon material, for example, there is low-temperature calcined carbon obtained by heat-treating a carbon precursor at a temperature of 550 ° C. to 1000 ° C. Specifically, coke, phenolic resin, polyparaphenylene, perylene
There is an uncarburized material which is heat-treated at a temperature of not more than ℃ and has a part of hetero atoms such as H, O and N remaining.

Further, the carbon precursor is used at 1000 ° C. to 2000 ° C.
There is a low crystalline carbonaceous material obtained by heat treatment in the range of ° C. Specifically, it is graphitizable carbon made from tar pitch obtained from petroleum or coal, and more specifically, there is coke, MCMB, meso-fuse pitch-based carbon fiber, pyrolytic vapor grown carbon fiber, etc. .

Then, the thermosetting resin is heated to 1000 ° C. to 140 ° C.
There is non-graphitizable carbon having a structure close to an amorphous structure typified by glassy carbon obtained by heat treatment at 0 ° C. More specifically, there are fired phenol resin, fired furfuryl alcohol resin, polyacrylonitrile-based carbon fiber, pseudo isotropic carbon, and the like.

There is a graphitic material obtained by heat-treating graphitizable carbon at 2000 ° C. or higher. Specific examples include artificial graphite, graphitized MCMB, graphitized mesofused pitch-based carbon fiber, and graphite whiskers. In addition to these, there is natural graphite among the graphitic materials, and its shape is scaly, earthy, and spherical.

The above carbon material can be crushed by a mortar, a ball mill, a meteor ball mill, a sand mill, a swirling jet mill or the like to have a predetermined particle size. If necessary, classification is performed after the crushing. be able to. Therefore, an arbitrary particle size can be selected, but it is preferable to select a particle size of 1 to 100 μm, and more preferable to select a particle size of 2 to 50 μm. Most preferably, the particle diameter is 5 to 30 μm.

The shape of the carbon material includes a sphere, a flake, a short fiber, a long fiber, a flake, and an irregular shape.

As the alloy as the negative electrode active material, one that can be alloyed with cations constituting the organic electrolyte can be selected. In the case of a lithium cation, specifically, Na, M
g, Al, Si, Ca, Zn, Ga, Ge, Zr, A
At least one or more alloys selected from the group consisting of g, Cd, Sn, Ir, Pt, Pb, and Bi can be used. Al, as a metal that forms an alloy with lithium,
Si, Zn, and Sn are preferred. Li metal can also be used as a negative electrode active material.

As oxides, oxyhydroxides, sulfates and carbides as the negative electrode active material, oxides, oxyhydroxides, sulfates and carbides of elements to be alloyed can be selected. , SnO ₂ , SiO, AgO, PbO,
Sn ₃ O ₂ (OH) ₂ , SnSO ₄ , ZrC, SiC and the like can be selected. Further, an amorphous negative electrode material obtained by adding P, S, B, etc. to these materials may be used.

As the nitride as the negative electrode active material, Li is used.
_{3-A M A N (0} ≦ A ≦ 0.6, M = Co, Ni, Cu) may be used.

As the negative electrode active material, the above-mentioned carbon materials, alloys, metals, oxides, oxyhydroxides, sulfates, nitrides and the like may be used alone or as a mixture of two or more. May be used. The method of mixing may be uniform or non-uniform, or a mode in which another material is carried on the surface of a certain material may be selected.

In the present invention, the mixture of two or more kinds having different materials and / or shapes as the negative electrode active material is constituted by a material selected from the above-mentioned negative electrode active materials.

As an example of a mixture of two or more kinds of different materials,
There are aluminum and non-graphitizable carbon, SnO and Li and graphitizable carbon, and the like. Examples of the mixture having different shapes include graphitized MCMB, flaky natural graphite, and graphitized MCM.
B and graphitized mesofused pitch carbon fibers.

Preferably, a mixture of two or more types of graphitic materials having different shapes and a lithium metal is used, and a mixture of two or more types of graphite materials having different shapes and a lithium alloy. Specifically, flaky natural graphite and graphitized MCMB and metal lithium, graphitized MCMB and graphitized mesofused pitch-based carbon fiber and metal lithium, graphitized MCMB and spherical natural graphite and Si, flaky natural graphite and graphite MCMB, spherical natural graphite, Al and the like.

The positive electrode active material used in the present invention includes:
As the inorganic compound, a composition formula of Li _B MO ₂ or Li _C
M ₂ O ₄ (where M is a transition metal, 0 ≦ B ≦ 1.0 ≦ C ≦
Complex oxides, oxides having tunnel-like pores, metal chalcogenides having a layered structure, oxyhydroxides and the like represented by 2) can be used. As a specific example, Li
CoO ₂ , LiNiO ₂ , NiOOHLi, LiMn
₂ O ₄ , Li ₂ Mn ₂ O ₄ , MnO ₂ , FeO ₂ , V ₂ O ₅ , V ₆
O ₁₃ , TiO ₂ , TiS _{2 and the} like can be mentioned. Examples of the organic compound include a conductive polymer such as polyaniline. Further, the above-mentioned various active materials may be mixed and used regardless of an inorganic compound or an organic compound.

For the above-mentioned positive electrode active material and negative electrode active material,
Surface treatment may be performed to improve charge / discharge characteristics, safety, life characteristics, storage stability, and the like. Specifically, washing with an acidic aqueous solution, washing with an alkaline aqueous solution, washing with neutral water, baking in an acidic atmosphere or a reducing atmosphere,
Is mentioned.

The binder that can be added to the positive and negative electrodes is selected from fluororesins such as polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, polyethylene, polypropylene, styrene butadiene rubber, polybutadiene, and polyvinylidene fluoride. it can.

The separator used in the present invention includes:
A conventionally known porous polypropylene or porous polyethylene may be used. Further, the above-described porous ion conductive polymer may be used. A filler can be added to these separators.

As the above filler, CaO, SiO
_2. Any fibrous material made of an oxide such as Al ₂ O ₃ , glass, or the like can be used.

The substrate of the electrode used in the present invention includes:
Any electronic conductor that does not cause a chemical change in the configured battery may be used. Specifically, the positive electrode is made of stainless steel,
Examples include steel, nickel, aluminum, titanium, and carbon. The negative electrode includes copper, stainless steel, titanium, nickel and the like. These materials need not be pure metals or materials, but may be alloys. Examples of the shape of the substrate include foils such as foils, films and sheets, nets, expanded lattices, foams, sintered bodies, porous bodies, and formed bodies of fibers. In addition, a substrate in which holes are formed in any shape may be used.

The shape of the battery used in the present invention is as follows.
Any of a square type, a cylinder type, a button type, a sheet type, a flat type, etc. may be used.

As the material of the battery case used in the present invention, a metal case made of stainless steel, aluminum, magnesium, iron or the like may be used, or a metal alloy case made of aluminum alloy, titanium alloy or the like may be used. Further, it may be formed by an aluminum laminate in which an aluminum foil and a resin film are combined. Specific examples of the resin film include polyprorylene, polyethylene, and a fluorine-based resin. However, any resin film that does not transmit an electrolytic solution can be used.

In the present invention, it is preferable that the reversible capacity of the positive electrode and the capacity of the negative electrode have the following relationship.

[Reversible capacity of positive electrode (mAh)] / {reversible capacity of negative electrode (mAh) + irreversible capacity of negative electrode (mAh)}
1 [Reversible capacity of the negative electrode] in the present invention refers to 0 V (vs. Li / L) at a current density of 10 hours or less (0.1 C) or less for an electrode using this carbon material as an active material.
i ⁺ ) This is the amount of electricity shown when discharged at the same current density after being charged with a constant current to the potential of i.sup. ^{+. In} the case of a graphite material, lithium intercalates mainly between the graphite layers, as is commonly known. 372 mA theoretically
h / g capacity is obtained. Also, [Irreversible capacity of negative electrode]
Is the difference between the amount of electricity charged to the negative electrode containing the negative electrode carbon material for the first time and the amount of electricity when subsequently discharged.
This is considered to be caused by a film-forming reaction occurring at the interface between the carbon anode material and the electrolyte, as is commonly believed. And
The “reversible capacity of the positive electrode” is not only a capacity in a region where the positive electrode active material can be charged and discharged, but also a capacity in a region having good cycle characteristics.

[0058]

EXAMPLES The present invention will be described below with reference to specific examples, but the present invention is not limited to these examples.

Example 1 First, a battery (A) according to the present invention was manufactured. Hereinafter, a method for manufacturing the positive electrode will be described. Lithium cobaltate 35wt%, acetylene black 4wt%, polyvinylidene fluoride (PVdF)
A mixture of 6 wt% and NMP 55 wt% was applied to an aluminum thin film, dried at 150 ° C., and NMP was evaporated to produce a positive electrode. This coating operation was performed on both surfaces of the aluminum thin film to produce a positive electrode having a positive electrode mixture layer on both surfaces. Thereafter, the electrode was compressed by a roll press to make the porosity of the active material layer 30 vol%.

Next, a method for producing the negative electrode (a) will be described. Graphitized MCMB 20wt%, flaky natural graphite 16w
t%, 4 wt% of PVdF, and 60 wt% of NMP are coated on a copper foil, dried at 150 ° C., and dried.
The MP was evaporated to form a negative electrode mixture layer. This coating operation was performed on both surfaces of the copper foil to produce an unpressed negative electrode having negative electrode mixture layers on both surfaces.

Subsequently, a polymer solution in which 10% by weight of polyacrylonitrile (PAN) and 90% by weight of NMP were applied to the unpressed negative electrode, allowed to stand for 7 minutes, and allowed to penetrate into the holes of the unpressed electrode. Immerse in distilled water for 3 minutes, remove NMP dissolving PAN with distilled water,
A porous polymer impregnation treatment for making PAN in the negative electrode pores porous was performed. The electrode was dried at 100 ° C. for 120 minutes to remove distilled water. Then, the negative electrode including the porous polymer was roll-pressed. Thereby, the porosity of the active material layer of the negative electrode became 30 vol%.

Next, the surface of the negative electrode was irradiated with an excimer laser having a wavelength of 193 nm and an irradiation energy density of 0.9 J / cm ^{2 using} Ar-F as a laser catalyst gas. One irradiation area was 0.5 mm × 0.5 mm, and one region was irradiated 10 times at 10 Hz. This irradiation was performed on the entire surface of the negative electrode, and the adjacent irradiation regions were overlapped with each other to prevent irradiation leakage.

As a result, the center line average roughness of the electrode
1.9 μmR before irradiation with Shima laser _aAnd excimer
11 μmR after laser irradiation_aIncreased.

In addition, since the lithium ion conductive polymer of the nonaqueous electrolyte battery according to the present invention is porous, lithium ions diffuse at high speed in the free nonaqueous electrolyte contained in the pores. Thus, unlike a conventional battery using a lithium ion conductive polymer having no communication hole, practical charge / discharge performance as a secondary battery can be obtained.

Each of the positive electrode and the negative electrode has a width of 20 m.
m, cut into length 500mm, thickness 27μm, width 22m
m of polyethylene separator. The positive electrode and the negative electrode were adjusted so that the reversible capacity of the positive electrode active material was 500 mAh and the reversible capacity of the negative electrode active material was 400 mAh. The irreversible capacity of the negative electrode active material is 50 mAh. After making the element, height 45mm, width 23mm,
It was inserted into a 6 mm thick stainless steel case. Further, an electrolytic solution obtained by adding 1 mol / l of LiPF ₆ to a mixed solution of ethylene carbonate and dimethyl carbonate at a volume ratio of 1: 1 was injected to produce a battery (A) having a nominal capacity of 450 mAh according to the present invention.

Comparative Example 2 Next, as a comparative example, a conventional battery (B) was manufactured. The positive electrode used was the same as the battery (A). Next, a negative electrode was prepared in the same manner as in Example 1, and used without excimer laser irradiation.

The negative electrode (b) and the positive electrode were 20 m wide.
m, cut into length 500mm, thickness 27μm, width 22m
m after winding with a polyethylene separator, height 4
It was inserted into a stainless steel case of 8 mm, width 24 mm and thickness 6.6 mm. Further, an electrolyte solution in which 1 mol / l of LiPF ₆ was added to a mixed solution of ethylene carbonate and dimethyl carbonate in a volume ratio of 1 to 1 was injected and sealed to produce a conventional battery (B) for comparison.

FIG. 1 shows discharge characteristics of the batteries (A) and (B). After constant-current charging to 4.15 V at 90 mA, constant-voltage charging at 4.15 V was performed for 3 hours. Then, after a rest time of 3 hours, constant current discharge was performed at 450 mA to 2.5 V. All charging and discharging were performed at room temperature.
It can be seen that the battery (A) according to the present invention has a higher capacity than the conventional battery (B). This is the discharge contribution of lithium metal. On the other hand, in the negative electrode of the battery (B), since the deposition of metallic lithium mainly occurred on the surface of the electrode, the metallic lithium became so-called dead lithium,
Can no longer contribute.

FIG. 2 shows the relationship between the amount of discharged electricity and the temperature of the battery (A) according to the present invention and the conventional battery (B) for comparison. The charging and discharging conditions were as follows: constant current charging to 4.15 V at 90 mAh, then constant voltage charging at 4.15 V for 3 hours;
After a pause, constant current discharge is performed at 450 mA to 2.5 V. All charging is room temperature, discharging is -20 ℃,-
The test was performed at 5 ° C, 10 ° C, and 25 ° C. It has been found that the battery (A) according to the present invention has a larger discharge capacity especially at a low temperature than the conventional battery (B).

Examples 2 to 8 The same as Example 1 except that the number of times of excimer laser irradiation on the negative electrode surface was changed.
Ten batteries each of Examples 2 to 8 were produced, and an internal short-circuit test was performed on these batteries. The internal short circuit test is 90
After the battery was charged at a constant current of 4.15 V at mA, the battery was charged at a constant voltage of 4.15 V for 3 hours, and a nail was inserted into the battery. The same internal short-circuit test was performed on the battery of Example 1.

Table 1 shows the relationship between the number of times of excimer laser irradiation, the center line average roughness of the electrode, and the number of bursts in an internal short-circuit test of a battery using this electrode.

[0072]

[Table 1]

As a result, in the batteries of Examples 2 to 4 in which the center line average roughness was smaller than 5 μm Ra, the batteries burst, but in Examples 1 and 5 in which the center line average roughness was 5 μm Ra or more.
It was found that the batteries of Nos. To 8 did not burst and were excellent in safety.

[0074]

According to the present invention, a reduction in charge / discharge capacity caused by a change in the shape of the electrode surface is reduced, and high-rate discharge characteristics and low-temperature characteristics are improved. In addition, by applying to electrodes that deposit metal lithium or lithium alloy on carbon material, which shows higher capacity than conventional electrodes, it is possible to manufacture electrodes with higher capacity, high rate discharge characteristics, and excellent low-temperature characteristics. It is assumed that.

In a battery having both the electrode and the porous polymer electrolyte, the electrode surface does not collapse, lithium does not deposit on the electrode surface, and a short circuit due to dendrite can be prevented. It is intended to provide a non-aqueous electrolyte battery having excellent performance.

[Brief description of the drawings]

FIG. 1 is a diagram showing discharge characteristics of a battery A according to the present invention and a conventional battery B.

FIG. 2 is a diagram showing a relationship between a discharge capacity and a discharge temperature of a battery A according to the present invention and a conventional battery B.

Claims (3)

[Claims] 1. The electrode surface has a center line average roughness (R _a ).
A non-aqueous electrolyte secondary battery comprising a positive electrode and / or a negative electrode having a thickness of 5.0 μm or more. 2. The method according to claim 1, wherein the ion-conductive porous polymer is disposed between the positive electrode and the negative electrode, and at least one of the positive electrode and the negative electrode contains the ion-conductive porous polymer. Non-aqueous electrolyte secondary battery. 3. The non-aqueous electrolyte secondary battery according to claim 1, wherein the negative electrode contains two or more types of negative electrode active materials having different materials and / or shapes.