JPH09274920A - Nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance battery with high reliability and high productivity by using electrodes improving the binding capacity between a coated film including active material powder and binder, and a collector, for suppressing the drop of active material powder. SOLUTION: In a nonaqueous electrolyte battery in which at least either positive electrode 2 or negative electrode 1 is formed of coated film including active material powder and binder (active material coating) on the surface of collectors 10, 11, the binder is PVDF(poly vinylidene fluoride) with mean molecular weight Mn of more than 1.0×10<5> , or the binder is a PVDF with apparent viscosity of 150mPa/s when 10weight% of PVDF is solved in N- methyl-2-pyrolidone(NMP) 90weight%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is one in which at least one of a positive electrode and a negative electrode has a coating film containing an active material powder and a binder formed on the surface of a current collector. The present invention relates to a non-aqueous electrolyte battery.

[0002]

2. Description of the Related Art As portable electronic devices have become smaller and lighter and have higher performance, power supplies to be used have been required to have smaller size, higher capacity, higher energy density and higher reliability. As a battery satisfying these requirements, a non-aqueous electrolyte primary battery using lithium in the negative electrode, a material capable of inserting and extracting lithium such as lithium metal, or an alloy thereof, or a carbon material is used in the negative electrode, and lithium is also used in the positive electrode. Non-aqueous electrolyte secondary batteries have been developed that use oxides that can be inserted and removed, or lithium-containing composite oxides.

In these batteries, since a nonaqueous electrolytic solution having a lower conductivity than that of an aqueous electrolytic solution is used, it is relatively difficult to increase the output. Therefore, in order to obtain a high output, a method is used in which the electrode is thinned and the electrode area is enlarged to keep the current value per unit area low.

In an actual battery, a thin sheet-shaped electrode is cut into strips for use. For example, in a cylindrical battery, a strip electrode and a separator are spirally wound and used.

When metallic lithium or an alloy of metallic lithium is used as an active material, metallic lithium and a lithium alloy themselves are formed into strips to form electrodes. When a powdery active material (hereinafter referred to as active material powder) is used, the strip electrode is usually prepared as follows.
After kneading the active material powder and the binder in water or an organic solvent to make a chiller, apply it to a current collector, dry it, press it to form a sheet, and then cut it into strips. And use it as an electrode. In the case of the positive electrode, a conductive agent is often used in addition to the active material powder and the binder.

As the binder, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF),
Fluororesin and other fluororesins, styrene-butadiene rubber,
Organic polymers such as styrene butadiene latex and carboxymethyl cellulose (CMC) are used.

Among them, PVDF is often used as a binder for non-aqueous electrolyte batteries because it has high chemical stability and high productivity due to good slurry properties.

[0008]

[Problems to be Solved by the Invention] However, PVD
Since F has a relatively low binding property, in the non-aqueous electrolyte battery using PVDF, the active material powder is cut off from the cut surface of the strip-shaped electrode or the electrode surface due to stress during electrode transportation and electrode winding. Could fall off and damage the separator that separates the positive electrode from the negative electrode, which could cause discharge failure. In non-aqueous electrolyte secondary batteries, stress is applied to the electrodes due to dimensional changes of the electrodes due to charging and discharging, and the coating film composed of active material powder, conductive agent, binder, etc. peels off from the current collector. However, this has been a cause of deterioration in cycle characteristics.

When the binding force of PVDF is not sufficient as described above, the reliability and productivity of the battery are deteriorated.

Therefore, in the present invention, an electrode is used in which the binding force between the coating film containing the active material powder and the binder and the current collector is improved, and the active material powder is prevented from falling off. Accordingly, it is an object of the present invention to provide a non-aqueous electrolyte battery having high performance, high reliability and high productivity.

[0011]

The present invention achieves the above-mentioned object, and at least one of a positive electrode and a negative electrode has an active material powder and a binder on the surface of a current collector. In a non-aqueous electrolyte battery formed by containing a coating film,
The binder is made of PVDF having a number average molecular weight Mn of 1.0 × 10 ⁵ or more.

Alternatively, in a non-aqueous electrolyte battery in which at least one of the positive electrode and the negative electrode has a coating film containing active material powder and a binder formed on the surface of a current collector,
The binder is N-methyl-2-pyrrolidone (NMP)
It is made of PVDF having an apparent viscosity of 150 mPa · s or more when dissolved by 10% by weight with respect to 90% by weight.

The term "apparent viscosity" as used herein means JIS-
It is an apparent viscosity defined by K7117, and as described above, it is a viscosity when dissolved in 10% by weight with respect to 90% by weight of NMP. Hereinafter, it is simply referred to as "apparent viscosity".

When the number average molecular weight Mn of PVDF or the apparent viscosity is less than the above-mentioned values, the active material powder falls off and the separator is damaged. Further, in the case of the non-aqueous electrolyte secondary battery, there is a problem that the coating film containing the active material powder and the binder is peeled off from the current collector to deteriorate cycle characteristics.

On the other hand, when the present invention is applied to use PVDF having a large number average molecular weight Mn or a large apparent viscosity, the active material powder is prevented from falling off, and the active material powder and the binder are combined. It becomes possible to suppress peeling between the coating film and the current collector.

This is because PVDF having a large number average molecular weight Mn or a large apparent viscosity as described above has a large molecular weight and a long molecular chain, so that the state of contact with the active material powder and the current collector is good, and The reason is that a single molecular chain can bind more active material powders and current collectors.

As described above, the binding force of PVDF improves depending on the number average molecular weight Mn or the apparent viscosity, but the number average molecular weight Mn is 1.5 × 10 ⁵ or more, or the apparent viscosity is 340 mPa · s or more. Then, the effect of suppressing peeling between the coating film containing the active material powder and the binder and the current collector becomes sufficient. Furthermore, the number average molecular weight Mn is 1.8.
× 10 ⁵ or more, or apparent viscosity of 600 mPa
If it is s or more, the binding force of PVDF will be maximized.

The number average molecular weight Mn of PVDF is
There is no particular upper limit to the viscosity, but these values increase
Too much, that is, the molecular weight of PVDF becomes too large
Therefore, it may be difficult to make paint. For this reason,
The number average molecular weight Mn of PVDF is 1.0 × 10.⁷As follows
It is suitable. The number average molecular weight Mn is 1.0 × 10.
⁷For PVDF, the viscosity is too high to measure.
It is possible. Therefore, the upper limit of the apparent viscosity is intentionally set.
Then, the maximum value that can be measured may be set.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described below with reference to the drawings. Here, the present invention was applied to a cylindrical non-aqueous electrolyte battery as shown in FIG.

In this non-aqueous electrolyte battery, a coating film (hereinafter referred to as a negative electrode active material-containing coating film) 15 containing negative electrode active material powder and a binder is formed on both surfaces of the negative electrode current collector 10. A coating film (hereinafter referred to as a positive electrode active material-containing coating film) 16 containing a positive electrode active material powder and a binder is formed on both surfaces of the negative electrode 1 and the positive electrode current collector 11 thus formed. The positive electrode 2 and the positive electrode 2 are stacked and wound via the separator 3 and housed in the battery can 5.

When this non-aqueous electrolyte battery is used as a primary battery, manganese dioxide, fluorocarbon, FeS, FeS ₂ , CuO, etc. can be used as the positive electrode active material, and lithium as the negative electrode active material. A metal or a lithium metal alloyed with Al, Pb, In or the like can be used.

The non-aqueous electrolyte battery is used as a secondary battery.
When used as a positive electrode active material, lithium ion
A substance capable of reversibly inserting and removing is used. For example, T
iS _Two, MoS_Two, V_TwoO_Five, V₆O₁₃, MnO_Two, L
iCoO_Two, LiNiO_Two, LiNi_xCo_yO_Two, L
iMn_TwoO_Four, LiMnO_TwoAnd the like. In powder form
The positive electrode active material used is generally an electron with a current collector.
A conductive agent is added to ensure conductivity. With this conductive agent
Is not particularly limited, but metal powder, carbon powder, etc. are used.
Can be For example, pyrolytic carbon such as carbon black,
And its graphitized products, artificial or natural flake graphite powder,
It is suitable to use carbon powder and carbon powder such as graphitized product.
You. Also, a mixture of these carbons can be used.

As the negative electrode active material when the non-aqueous electrolyte battery is used as a secondary battery, lithium metal or an alloy of lithium metal and Al, Pb, In or the like is used. Further, by using a carbon material capable of inserting and extracting lithium as the negative electrode active material, it is possible to obtain a battery having further excellent cycle life. The carbon material for the negative electrode is not particularly limited, but those obtained by thermal decomposition or calcining carbonization of various organic compounds can be used.
Further, these graphitized products are also used. Furthermore, naturally occurring natural graphite can also be used.

The non-graphitizable carbons have a large charge / discharge capacity per weight and are excellent in cycle characteristics. In particular, (00
2) The surface spacing is 0.370 nm or more, and the true density is 1.70.
It is preferably less than g / cm ³ and has no exothermic peak at 700 ° C. or higher in differential thermal analysis in an air stream. Materials having such properties include carbonaceous materials obtained by carbonizing an organic material by a method such as firing, and the starting material for carbonization is furfuryl alcohol or a furfural homopolymer or furan furan copolymer. Resins are preferred. Specific examples thereof include polymers composed of furfural + phenol, furfuryl alcohol + dimethylol urea, furfuryl alcohol, furfuryl alcohol + formaldehyde, furfuryl alcohol + furfural, furfural + ketones and the like. Alternatively, a petroleum pitch having a hydrogen / carbon atom ratio of 0.6 to 0.8 is used as a raw material, a functional group containing oxygen is introduced into the petroleum pitch, and so-called oxygen cross-linking is performed to produce a precursor having an oxygen content of 10 to 20% by weight. After that, a carbonaceous material obtained by firing can also be used. Furthermore, when carbonizing furan resin, petroleum pitch, or the like, a carbonaceous material having a large doping amount with respect to lithium by adding a phosphorus compound or a boron compound can also be used.

The graphite material is preferable for obtaining a high capacity battery since it has a high true density and an improved electrode filling property. As the usable graphite material, the true specific gravity needs to be 2.10 g / cm ³ or more, and 2.18 g / cm ³ or more is more preferable in order to obtain higher negative electrode mixture filling property. preferable. In order to obtain such a true specific gravity, the plane spacing of the (002) plane obtained by the X-ray diffraction method is 0.335 nm to
Must be 0.34 nm, 0.335 nm
More preferably, it is about 0.337 nm. The crystallite thickness in the C-axis direction is preferably 16.0 nm or more,
It is more preferably 24.0 nm or more. JIS-K
The bulk specific gravity determined by 1469 is 0.3 g / cm ^3.
It is necessary to be above. Further, the average shape parameter (X) representing the flatness of the graphite material particle shape is x ≦ 1.
It is preferably 25. Further, laser Raman spectroscopy is a measurement method in which the information on the vibration of the crystal structure of the carbon material is reflected with high sensitivity, but the G value obtained from the Raman spectrum is an effective index for evaluating microscopic structural defects. Is one. The G value is represented by the ratio of the area intensity of the Raman band derived from the complete graphite structure to the area intensity of the Raman band derived from the amorphous structure in the carbon material, and the G value is preferably 2.5 or more. If the G value is less than 2.5, a true specific gravity of 2.1 g / cm ³ or more may not be obtained.

Further, as the negative electrode current collector 10 holding the negative electrode active material powder as described above, a copper foil, stainless steel foil, nickel foil or the like having a thickness of 5 to 20 μm can be used. On the other hand, as the positive electrode current collector 11, an aluminum foil, a stainless steel foil, a nickel foil or the like having a thickness of 10 to 40 μm can be used. Note that any of the current collectors 10 and 11 is not limited to the foil shape, and a mesh shape or a mesh shape made of expanded metal or the like can be used.

Further, the separator 3 to be interposed between the negative electrode 1 and the positive electrode as described above is not particularly limited, and examples thereof include woven fabric, non-woven fabric, synthetic resin microporous film and the like. When a thin electrode having a large area is used, a synthetic resin microporous film, particularly a polyolefin microporous film is preferably used. Specifically, a microporous membrane made of polyethylene and polypropylene, or a microporous membrane obtained by combining these is used.

As the battery can 5 for accommodating the one in which the negative electrode 1, the separator 3 and the positive electrode 2 as described above are wound and stacked (hereinafter referred to as a spiral electrode body), for example, A cylindrical case made of nickel-plated iron can be used. The spiral electrode body described above is wound around the center pin 14.

When the spirally wound electrode body is housed in the battery can 5, the insulating plates 4 are arranged on both upper and lower surfaces thereof, and the negative electrode lead 12 led out from the negative electrode current collector 10 is provided.
Is electrically connected to the bottom of the battery can 5, and the positive electrode lead 13 led out from the positive electrode current collector 11 is electrically connected to the battery lid 7 via the safety valve device 8.

An organic electrolytic solution prepared by dissolving an electrolyte in an organic solvent is injected into the battery can 5, and the battery lid 7 has an insulating sealing gasket 6 coated with asphalt.
It is fixed by being caulked through.

Here, as the electrolyte contained in the organic electrolytic solution, any electrolyte can be used as long as it is used in this type of battery. For example, in addition to LiPF ₆ , LiCl
O ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiB
_{(C 6 H 5) 4,} LiCl, LiSO 3 CH 3, LiN
_{(SO 2 CF 3) 2,} LiC (SO 2 CF 3) 3 and the like. The organic solvent is not particularly limited, for example, ethylene carbonate, propylene carbonate, butylene carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, γ-butyrolactone, sulfolane, 1,2-dimethoxyethane, 1,3-dimethoxy. At least one selected from propane, diethyl ether, tetrahydrofuran and 2-methyltetrahydrofuran can be mixed and used.

In the present embodiment, the electrode active material-containing coatings 15 and 16 of the spirally wound electrode body as described above.
As a binder used together with the active material powder, the number average molecular weight Mn was 1.0 × 10 ⁵ or more, or 10% by weight was dissolved in 90% by weight of N-methyl-2-pyrrolidone (NMP). PVDF having an apparent viscosity of 150 mPa · s or more is used.

PVDF is generally obtained by suspension polymerization or emulsion polymerization of 1,1-difluoroethylene in an appropriate reaction medium together with an additive such as an assembly initiator, a suspending agent or an emulsifying agent. The product obtained by either of the production methods has high chemical stability, and high productivity can be obtained due to good slurry properties, so that it can be used as a binder.

The molecular weight of this PVDF can be controlled by using various polymerization degree adjusting agents or chain transfer agents. For example, bisalkyl or the like is used in suspension polymerization, and chlorofluoromethane or the like is used in emulsion polymerization to adjust the degree of polymerization, and PVDF having various molecular weights is used.
Can be obtained. Here, in this way, the number average molecular weight Mn is set to 1.0 × 10 ⁵ or more, or the apparent viscosity is set to 150 mPa · s or more. Thereby, the binding property of PVDF can be improved.

The number average molecular weight Mn shown here is determined by gel permeation chromatography (GP
It is measured by C). As a measuring device, a product name: HLC8020 manufactured by Tosoh Corporation is used, and as a column, product names: G5000H6, G4008H8, G3.
A product obtained by connecting three 0008 was used. UV for detection
Using a detector, the eluent is 0.01 mol / l L
An iBr / NMP solution was used. Monodisperse polystyrene having various molecular weights was used as a standard sample. LiB as the eluent
The reason for adding r is to cancel the electrostatic interaction between the polymer and the gel of the column by adding the electrolyte and obtain a normal chromatogram.

In this embodiment, the PVD used
The apparent viscosity of F is also specified as described above. This is because the intrinsic viscosity of the polymer solution is generally used as a standard for the molecular weight of the polymer, and the apparent viscosity also has a value having a correlation with the molecular weight. PV with high molecular weight
DF has a high solution viscosity and a high slurry viscosity.
When the apparent viscosity of PVDF is increased in this way, the binding property is improved. The reason why the binding property is improved is that the viscosity of the slurry is increased and the dispersibility of the active material powder and PVDF is improved, in addition to the increase in the molecular weight.

Here, the apparent viscosity shown here is J
It is measured according to IS-K7117. That is, the solvent N-methyl-2-pyrrolidone (NMP) 90
10% by weight of PVDF is dissolved in the weight%, and a B-type viscometer (manufactured by Tokimec, trade name: DIGITAL VISCOMETER D
VL-BII) according to the S method (using a single cylinder rotational viscometer). The measurement temperature was 23 ° C., SB3 was used as the spindle, and the spindle rotation speed was 30 rpm.

Although the embodiment of the non-aqueous electrolyte battery to which the present invention is applied has been described above, it goes without saying that the present invention is not limited to the above-described embodiment, and it is needless to say that the flat rectangular non-aqueous electrolyte is used. Modifications and changes can be made as appropriate without departing from the spirit of the present invention, such as application to electrolytic solution batteries.

[0039]

EXAMPLES Here, a non-aqueous electrolyte battery as shown in the above-mentioned embodiment was actually manufactured and its characteristics were evaluated.

Example 1 In this example, a number average molecular weight Mn was used as a binder.
Is 2.43 × 10 ⁵ , and apparent viscosity is 1391 mP
A non-aqueous electrolyte secondary battery was produced using PVDF of a · s.

Specifically, first, the petroleum pitch is set to 1200.
After calcination at ℃, it was heat-treated at 3000 ℃ in an inert gas atmosphere, and then ground to obtain a negative electrode active material powder made of an artificial graphite material. As a result of powder X-ray diffraction measurement of the negative electrode active material powder, the (002) plane spacing was 0.337 nm, and the crystallite thickness in the C-axis direction was 30 nm. G value by laser Raman method is 1
3.6, true specific gravity by pycnometer method is 2.20 g / c
m ³ . The average particle size measured by laser diffraction type particle size distribution was 33 μm, the bulk specific gravity determined by JIS-K1469 was 1.18 g / cm ³ , and the average shape parameter was 3.6.

Subsequently, the number average molecular weight Mn was 2.43 × 1.
0 is ^5, P apparent viscosity is 1391mPa · s
VDF (this is referred to as sample A) was prepared, 90 parts by weight of the negative electrode active material powder and 10 parts by weight of the binder made of sample A were mixed and dispersed in NMP to prepare a slurry.

Then, the above-mentioned slurry is applied to the surface of the negative electrode current collector 10 made of a strip-shaped copper foil having a thickness of 10 μm,
After drying, the negative electrode 1 was prepared by compression molding to form the negative electrode active material-containing coating film 15.

Further, 0.5 mol of lithium carbon and 1 mol of carbon cobalt were mixed and baked in air at 900 ° C. for 5 hours and then crushed to obtain LiCoO 2 having an average particle size of 15 μm.
_Two powders were obtained. Regarding this LiCoO ₂ powder, X
As a result of line diffraction measurement, it was in good agreement with the peak of LiCoO ₂ registered in the JCPDS file. Subsequently, 91 wt% of the positive electrode active material powder composed of 95 wt% of this LiCoO ₂ powder and 5 wt% of carbon lithium powder, 6 wt% of graphite (conductive agent), and 3 wt% of the binder of Sample A were mixed. , NMP were dispersed to prepare a slurry.

Then, the above-mentioned slurry is applied to the surface of the positive electrode current collector 11 made of a strip-shaped aluminum foil having a thickness of 20 μm, dried and then compression-molded to form the positive electrode active material-containing coating film 16. Thus, the positive electrode 2 was produced.

Next, a separator 3 made of a microporous polypropylene film having a thickness of 25 μm is prepared, and the separator 3, the positive electrode 2, the separator 3 and the negative electrode 1 are laminated in this order and then wound to form a spiral shape. An electrode body was produced. Then, the spirally wound electrode body was housed in a cylindrical battery can 5 having a diameter of 18 mm and a height of 65 mm, and 1 mol / l of LiPF ₆ was added to a mixed solvent of 50% by volume of ethylene carbonate and 50% by volume of diethyl carbonate. A non-aqueous electrolyte battery was completed by injecting an organic electrolyte solution dissolved at a concentration. The non-aqueous electrolyte battery manufactured in this manner is used as the sample battery of Example 1.

Examples 2 to 5 Here, as the binder contained in the negative electrode active material-containing coating film 15 of the negative electrode 1, PVDF having a number average molecular weight Mn and an apparent viscosity different from those in Example 1 was used. I was there.

Concretely, as PVDF, Sample B whose number average molecular weight Mn and apparent viscosity are shown in Table 1 is used.
-Use E was prepared. Table 1 also shows the number average molecular weight Mn and the apparent viscosity of Sample A used in Example 1.

[0049]

[Table 1]

Then, a nonaqueous electrolyte battery was prepared in the same manner as in Example 1 except that Sample B was used as the binder contained in the negative electrode active material-containing coating film 15 of the negative electrode 1. The sample battery of Example 2 was used. Further, a non-aqueous electrolyte battery was prepared in the same manner as in Example 1 except that Sample C was used as the binder contained in the negative electrode active material-containing coating film 15, and this was used as the sample battery in Example 3. did. Further, a non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that Sample D was used as the binder contained in the negative electrode active material-containing coating film 15, and this was used as the sample battery of Example 4. did. Further, as a binder contained in the negative electrode active material-containing coating film 15, Sample E
A non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that was used as a sample battery of Example 5.

Comparative Example 1 Here, PVDF having a number average molecular weight Mn and an apparent viscosity different from those in Example 1 was used as the binder contained in the negative electrode active material-containing coating film 15 of the negative electrode 1.

Specifically, a non-aqueous electrolyte battery was prepared in the same manner as in Example 1 except that the sample F shown in Table 1 was used as the binder contained in the negative electrode active material-containing coating film 15. Then
Thereby, the sample battery of Comparative Example 1 was obtained.

Examples 6 to 9 Here, as the binder contained in the positive electrode active material-containing coating film 16 of the positive electrode 2, PVDF having a number average molecular weight Mn and an apparent viscosity different from those in Example 1 was used. I was there.

Specifically, as the binder contained in the positive electrode active material-containing coating film 16, samples B to E shown in Table 1 were used.
A non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that was used. Sample B was used as the binder contained in the positive electrode active material-containing coating 16 as the sample battery of Example 6, and Sample B was similarly used as the sample battery of Example 7, and the same sample was used. The sample battery using D was the sample battery of Example 8, and the sample battery using Sample E was the sample battery of Example 9.

Comparative Example 2 Here again, PVDF having a number average molecular weight Mn and an apparent viscosity different from those of Example 1 was used as the binder contained in the positive electrode active material-containing coating film 16 of the positive electrode 2.

Specifically, a non-aqueous electrolyte battery was prepared in the same manner as in Example 1 except that Sample F shown in Table 1 was used as the binder contained in the positive electrode active material-containing coating film 16. Then
As a result, a sample battery of Comparative Example 2 was obtained.

Example 10 In this example, a non-aqueous electrolyte primary battery was prepared by using Sample A as the binder contained in the positive electrode active material-containing coating film 16 of the positive electrode 2.

Specifically, first, FeS _{2 having a} purity of 96% is prepared.
Was prepared and passed through a mesh having an opening of 44 μm to obtain FeS ₂ powder having an average particle size of 13 μm. continue,
91 parts by weight of this FeS ₂ powder, graphite (conductive agent)
6% by weight and 3% by weight of the binder consisting of sample A are mixed, and N
A slurry was prepared by dispersing in MP.

Then, the above-mentioned slurry is applied to the surface of the positive electrode current collector 11 made of a strip-shaped aluminum foil having a thickness of 20 μm, dried and then compression molded to form the positive electrode active material-containing coating film 16. Thus, the positive electrode 2 was produced.

Further, the metallic lithium wound in a roll shape was cut to prepare the negative electrode 1, and the negative electrode lead 12 made of nickel was pressure-bonded to the end of the negative electrode 1.

Next, a microporous polypropylene having a thickness of 25 μm was prepared.
Prepare a separator 3 made of ren film,
In this order, the generator 3, the positive electrode 2, the separator 3, and the negative electrode 1
Fabricate spiral electrode body by stacking on
did. A cylindrical type with a diameter of 18 mm and a height of 65 mm
The spirally wound electrode body is housed in the battery can 5 and
Carbonate 50% by volume, Dimethoxyethane 50% by volume
LiCF as a mixed solvent of _ThreeSO_ThreeIs 0.7 mol / l
Non-aqueous electrolyte battery by injecting dissolved organic electrolyte
Was completed. Non-aqueous electrolyte battery produced in this way
Is a sample battery of Example 10.

Examples 11 to 14 Here, as the binder contained in the positive electrode active material-containing coating film 16 of the positive electrode 2, the example 10 is the number average molecular weight Mn.
And PVDF with different apparent viscosities were used.

Specifically, as the binder contained in the positive electrode active material-containing coating film 16, Samples B to E shown in Table 1 were used.
A nonaqueous electrolyte battery was produced in the same manner as in Example 10 except that was used. Note that the sample B was used as the binder contained in the positive electrode active material-containing coating film 16 as the sample battery of Example 11, and the sample B was similarly used as the sample battery of Example 12.
The sample battery of Example 13 was the sample battery of Example 13, and the sample battery of Example 13 was the sample battery of Example 13.

Comparative Example 3 Here again, PVDF having a number average molecular weight Mn and an apparent viscosity different from those in Example 10 was used as the binder contained in the positive electrode active material-containing coating film 16 of the positive electrode 2.

Specifically, a non-aqueous electrolyte battery was prepared in the same manner as in Example 10 except that Sample F shown in Table 1 was used as the binder contained in the positive electrode active material-containing coating film 16. Then, a sample battery of Comparative Example 3 was obtained.

Evaluation of Characteristics The characteristics of the sample batteries manufactured as described above will be evaluated below.

Examples 1 to 9 which are non-aqueous electrolyte secondary batteries,
Regarding the sample batteries of Comparative Examples 1 and 2, the binding force between the negative electrode active material-containing coating film 15 and the negative electrode current collector 10 or the binding force between the positive electrode active material-containing coating film 16 and the positive electrode current collector 11, and cycle retention rate. Example 10 which is a non-aqueous electrolyte primary battery
14 and the sample batteries of Comparative Example 3, the binding force between the positive electrode active material-containing coating film 16 and the positive electrode current collector 11 and the non-defective rate were examined.

The binding force between the active material-containing coatings 15 and 16 and the current collectors 10 and 11 is determined according to JIS-K5400-8.
The evaluation was made based on the measurement results by the cross-cut tape method specified in 5.2. That is, first, about 0.5 per cut and one scratch at a constant speed with a cutter knife at one central portion of the active material-containing coatings 15 and 16 of the negative electrode 1 or the positive electrode 2.
Over a period of 2 seconds, a grid-like cut with 100 mm intervals was provided. Subsequently, a cellophane adhesive tape having a width of 18 mm and an adhesive force of 2.94 N / 10 mm or more specified in JIS-Z1522 is formed on the grid and the length of the adhesive portion is about 50 m.
m, and then rub the above-mentioned adhesive part with an eraser specified in JIS-S6050 to completely adhere the cellophane adhesive tape to the active material-containing coatings 15 and 16 of the electrodes 1 and 2. It was Then, two minutes after applying the cellophane adhesive tape, hold one end of the cellophane adhesive tape, and while holding it vertically to the application surface of the active material-containing coatings 15 and 16, pull this cellophane adhesive tape momentarily. I peeled it off. By this operation, the number of lattices in which the active material-containing coatings 15 and 16 were not peeled off was counted, and the ratio of the remaining lattices was calculated. Then, this measurement was repeated 5 times to obtain an average value, and this numerical value was used to evaluate the binding strength. Regarding the sample batteries of Examples 1 to 5 and Comparative Example 1, the binding force between the negative electrode current collector 10 and the negative electrode active material-containing coating film 15 in the negative electrode 1 was determined, and Examples 6 to 9 and Comparative Example 2 were obtained.
For the sample batteries of Examples, Examples 10 to 14 and the sample batteries of Comparative Example 3, the positive electrode current collector 11 in the positive electrode 2 was used.
The binding force between the positive electrode active material-containing coating film 16 and

As for the cycle maintenance rate, the upper limit voltage is 4.
After setting the current in the constant current region at 2V to 1A and charging the battery for 2.5 hours, the cycle of discharging to 2.5V at 0.7A constant current was repeated to obtain the discharge capacity up to 2.75V. It is calculated as the ratio of the capacity at the 100th cycle to the capacity at the cycle.

Further, the non-defective rate is determined by discharging up to 0.5 V with a constant current of 0.7 A and obtaining the discharge capacity up to 0.9 V.
From this average value of the discharge capacity, the case where the discharge capacity is lower than 5% is determined to be defective, and the ratio not determined to be defective is calculated.

The results are shown in Tables 2-4.

[0072]

[Table 2]

[0073]

[Table 3]

[0074]

[Table 4]

Further, the relationship between the number average molecular weight Mn of PVDF used for the negative electrode 1 of the non-aqueous electrolyte secondary battery and the above-mentioned binding force (lattice residual rate by the cross-cut tape method) and cycle maintenance rate is shown in FIG. 2 as well as the relationship between the apparent viscosity of PVDF and the binding strength and cycle retention rate. Similarly, FIG. 4 shows the relationship between the number average molecular weight Mn of PVDF used for the positive electrode 2 of the non-aqueous electrolyte secondary battery and the binding force and the cycle retention rate. Similarly, the apparent viscosity of PVDF and the binding force and the cycle retention rate were also shown. Figure 5 shows the relationship with the rate
Shown in Furthermore, FIG. 6 shows the relationship between the number average molecular weight Mn of PVDF used for the positive electrode 2 of the non-aqueous electrolyte primary battery and the binding force and the good product ratio. Similarly, the relationship between the apparent viscosity of PVDF and the binding force and the good product ratio is shown. Is shown in FIG.

From Tables 2 to 4 and FIGS. 2 to 7, as the binder,
As PVDF having a higher number average molecular weight Mn and a higher apparent viscosity is used, the binding force between the current collectors 10 and 11 and the active material-containing coatings 15 and 16 in the electrode electrodes 1 and 2 is improved, and the cycle retention rate or the good product rate is improved. It turns out that also improves.

The number average molecular weight Mn is 1.0 × 10.
PVDF with an apparent viscosity of ⁵ or more and an apparent viscosity of 150 mPa · s or more
It was found that, by using, the good binding force can be obtained, and the cycle retention rate and the non-defective rate are also excellent. It was also found that when PVDF having a number average molecular weight Mn of 1.8 × 10 ⁵ or more and an apparent viscosity of 600 mPa · s or more is used, the binding force is almost maximized.

[0078]

As is apparent from the above description, when the present invention is applied, the binding force between the coating film containing the active material powder and the binder and the current collector can be improved, It is also possible to prevent the active material powder from falling off. Therefore, it is possible to provide a non-aqueous electrolyte battery that has high performance and high reliability and productivity.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a configuration example of a non-aqueous electrolyte battery.

FIG. 2 shows P used for a negative electrode of a non-aqueous electrolyte secondary battery.
It is a characteristic view which shows the relationship of the number average molecular weight Mn of VDF, the lattice retention rate by a cross-cut tape method, and a cycle maintenance rate.

FIG. 3 P used for the negative electrode of a non-aqueous electrolyte secondary battery
It is a characteristic view which shows the relationship between the apparent viscosity of VDF, the lattice residual rate by the cross-cut tape method, and the cycle maintenance rate.

FIG. 4 P used for a positive electrode of a non-aqueous electrolyte secondary battery
It is a characteristic view which shows the relationship of the number average molecular weight Mn of VDF, the lattice retention rate by a cross-cut tape method, and a cycle maintenance rate.

FIG. 5: P used for the positive electrode of a non-aqueous electrolyte secondary battery
It is a characteristic view which shows the relationship between the apparent viscosity of VDF, the lattice residual rate by the cross-cut tape method, and the cycle maintenance rate.

FIG. 6 P used for a positive electrode of a non-aqueous electrolyte primary battery
It is a characteristic view which shows the relationship of the number average molecular weight Mn of VDF, the lattice retention rate by a cross-cut tape method, and a cycle maintenance rate.

FIG. 7: P used for the positive electrode of a non-aqueous electrolyte primary battery
It is a characteristic view which shows the relationship between the apparent viscosity of VDF, the lattice residual rate by the cross-cut tape method, and the cycle maintenance rate.

[Explanation of symbols]

1 negative electrode, 2 positive electrode, 3 separator,
4 insulating plates, 5 battery cans, 6 sealing gaskets,
7 battery lid, 8 safety valve device, 10 negative electrode current collector,
11 positive electrode current collector, 12 negative electrode lead, 13 positive electrode lead, 14 center pin, 15 negative electrode active material-containing coating film, 16 positive electrode active material-containing coating film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Ono 1-1 Shimosugishita, Takakura, Hiwada Town, Koriyama City, Fukushima Prefecture Sony Energy Tech Inc.

Claims (4)

[Claims] 1. A non-aqueous electrolyte battery in which at least one of a positive electrode and a negative electrode has a coating film containing an active material powder and a binder formed on the surface of a current collector. A non-aqueous electrolyte battery, wherein the binder comprises polyvinylidene fluoride having a number average molecular weight Mn of 1.0 × 10 ⁵ or more. 2. The number average molecular weight Mn is 1.8 × 10 ^5.
It is above, The non-aqueous electrolyte battery of Claim 1 characterized by the above-mentioned. 3. A non-aqueous electrolyte battery in which at least one of a positive electrode and a negative electrode has a coating film containing an active material powder and a binder formed on the surface of a current collector. 90% by weight of N-methyl-2-pyrrolidone
And the apparent viscosity when dissolved by 10% by weight is 15
A non-aqueous electrolyte battery comprising a polyvinylidene fluoride having a pressure of 0 mPa · s or more. 4. The non-aqueous electrolyte battery according to claim 3, wherein the apparent viscosity is 600 mPa · s or more.