JP2003017122A - Nonaqueous secondary cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous lithium ion secondary cell having good discharging rate property, cycle property, and leakage resistant property. SOLUTION: For the secondary cell housing cell elements, composed of rechargeable positive electrode and negative electrode facing each other interposing a separator, and electrolyte liquid in a cell case, the space in the cell case not occupied by the cell elements, is filled with a polymer of which, the volume fulfils the formula; 0.2<=(Wp×SWp)/(We-ρs×Vcal)<=1.0, where, Wp represents mass of the polymer, SWp represents swelling degree of the polymer, We represents total mass of electrolyte liquid poured into the cell, ρs represents specific gravity of the electrolyte liquid, Vcal represents total cubic volume of pores in the positive electrode, the negative electrode and the separator.

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention
Non-aqueous secondary batteries, especially lithium ion secondary batteries
It is about. [0002] 2. Description of the Related Art In recent years, with the development of electronic portable devices,
There is a remarkable progress in the development of a battery that can be a driving source for a battery. That
Among them, lithium ion secondary batteries have high energy density
It has attracted particular attention because of its presence. Currently, generally
Known lithium ion secondary batteries are used as positive electrode active materials.
Contains transition metals such as cobalt, nickel, and manganese.
Titanium composite oxide and carbon dioxide containing graphite as the negative electrode active material
Materials, amorphous alloys, amorphous metal oxides, etc.
Using a material that can reversibly store and release lithium,
As propylene carbonate, ethylene carbonate
Aprotic organic solvent such as LiPF₆, LiBF_Four
And LiClO_FourElectrolyte between the positive and negative electrodes.
A mechanism to charge and discharge by moving the lithium ions
Have. The active material used for both poles is energy density
, The size and weight of the battery can be reduced. others
Lithium ion secondary batteries are expected to be smaller and lighter
Camera-integrated VTRs or mobile devices such as mobile phones
It is increasingly used. [0003] In particular, recently, a lithium ion secondary battery
From the metal cans such as stainless steel and aluminum,
Connect a layer of metal foil such as aluminum to a layer of polymer sheet.
Changed to a laminated film bonded with adhesive,
Sheet type with lighter weight and thinner than the battery
Batteries have been developed. Laminated film is metal can
The strength is lower than that of
Sealed by heat-sealing with each other or through resin
Are generally stopped by welding in metal cans.
Low strength compared to bonding, handling during battery manufacturing or after commercialization
Countermeasures for situations where the exterior body is damaged due to damage and the electrolyte leaks
Needs to be done enough. Therefore, plastics containing plasticizer
Solid electrolyte battery with a solid electrolyte between the positive and negative electrodes
Are being studied. [0004] However, a large amount of plasticizer is added to the solid electrolyte.
Improves ionic conductivity, but maintains mechanical strength
Because it is difficult to
Short circuit may occur. The resulting solid electrolyte machine
The amount of plasticizer is limited in order to secure
As a solid electrolyte with sufficient electrical conductivity was not obtained,
The ion conductivity is low compared to the rate characteristics and
At present, cycle characteristics are inadequate.
You. Also, a solid electrolyte is provided between the electrodes in battery production.
For this purpose, a plasticizer containing
Solid electrolyte coated with body electrolyte or formed into a film
A quality membrane must be inserted between the electrodes. For this reason
Needs to introduce new equipment and increase production processes compared to liquid batteries
Therefore, there is also a problem of increasing the manufacturing cost. [0005] SUMMARY OF THE INVENTION The present invention is based on the above circumstances.
It has been made in view of the
Non-aqueous battery with battery characteristics, easy to manufacture and low cost
Disclosed liquid secondary battery and method for manufacturing the same. [0006] Means for Solving the Problems The present inventors have solved the above problems.
We worked diligently to solve the problem. As a result, the solid
Even without using an electrolyte, the positive electrode and the negative electrode
To absorb the electrolyte between the facing battery element and battery exterior.
By adding an appropriate amount of swellable polymer, extra electrolyte
To improve the liquid leakage resistance.
Issued. The required amount of electrolyte in the battery container
In general, the positive electrode, negative electrode and separator absorb up to saturation
Amount, i.e., the amount of voids in the positive electrode, negative electrode, and separator.
Battery performance.
It is a calculation that can be fully demonstrated. But general
The method of injecting the electrolyte into the battery is as follows.
And a lead that can conduct current to the positive and negative electrodes.
After the injection, inject the electrolyte into the exterior,
This is a method of sealing the part that has been
You. In this injection method, part of the injected electrolyte solution is
Normally, the above required amount
In reality, an excessive amount of electrolyte is injected as compared with the above. [0007] The present investigators studied the leakage in detail.
As a result, the electrolyte existing between the battery element and the package
It was found to be the main cause. Therefore, the present invention
In the battery element, the positive and negative electrodes face each other with a separator
Polymer that can absorb and swell the electrolyte inside the exterior body except for
Of the liquid leaking between the battery element and the package.
Immobilization of excess electrolyte, which is the main cause, with polymer
Thus, the liquid leakage resistance can be improved. In the present invention, the battery element
Do not change the structure of the positive electrode, negative electrode,
Can improve liquid leakage resistance and can be used with conventional liquid batteries.
Maintain good ionic conductivity and obtain batteries with good performance
be able to. In the present invention, the battery exists between the battery element and the outer package.
To fix the electrolyte by absorbing and swelling it in the polymer
The mass of the polymer to be added and the degree of swelling of the polymer are as follows:
When the relationship is expressed by the equation (1), the battery performance and leakage resistance
It has excellent performance in both properties.   0.2 ≦ (Wp × SWp) / (We−ρs × Vcal) ≦ 1.0 (1) Wp: mass of polymer SWp: Swelling degree of polymer We: total electrolyte solution mass injected into the battery ρs: specific gravity of electrolyte Vcal: Total volume of voids in positive electrode, negative electrode and separator
Product (calculated value) Here, SWp is the degree of swelling of the polymer and is expressed by the following equation.
Is shown. SWp = mass of electrolyte absorbed by polymer
/ Measurement of polymer swelling before immersion in electrolyte at room temperature
The polymer is converted to the electrolyte under the condition (25 ° C)
After immersion and holding for 3 days, the mass is measured and calculated. Vcal is the positive electrode, the negative electrode, and the
It is the amount of void (calculated value).
The difference between the true specific gravity of each constituent material and the measured specific gravity, and
And the volume they occupy. Here (Wp
× SWp) indicates the mass of the electrolyte that can be absorbed by the polymer.
On the other hand, (We-ρs × Vcal) exists outside the battery element.
Indicates the mass of the existing electrolyte. (Wp × SW) in equation (1)
p) / (We-ρs × Vcal) is less than 0.2
The amount of electrolyte absorbed by the polymer is small,
And no sufficient effect was obtained, and (Wp × SWp) / (We−
ρs × Vcal) exceeds 1.0, the positive electrode, the negative electrode,
The polymer absorbs the electrolyte present in the voids of the separator.
As a result, battery performance such as cycle characteristics deteriorates.
Particularly preferably, (Wp × SWp) / (We-
ρs × Vcal) is a value of 0.3 or more and 0.8 or less.
This is desirable in terms of leakage resistance and battery performance. [0010] The degree of swelling of the polymer is not particularly specified.
However, if it is less than 1, there is no space between the battery element and the package.
Absorbs excess electrolyte present by polymer swelling
Requires the addition of a large amount of polymer into the battery.
Energy per unit volume is reduced
Difficult. Improved swelling resistance with swelling degree of 1 or more
However, if the number is 4 or more, leakage is likely to occur with a small amount of addition.
Energy per unit volume of battery due to liquid resistance
It is not necessary to reduce the density. Therefore, the present invention can be charged and discharged.
The positive electrode and the negative electrode are
Solution is a secondary battery that is housed in a battery
And fill the space inside the battery exterior body excluding the battery element with the following formula.
Non-aqueous system characterized by containing an amount of polymer
Next battery.   0.2 ≦ (Wp × SWp) / (We−ρs × Vcal) ≦ 1.0 (1) Wp: mass of polymer SWp: Swelling degree of polymer We: total amount of electrolyte injected into the battery ρs: specific gravity of electrolyte Vcal: Total volume of voids in positive electrode, negative electrode and separator
product [0011] BEST MODE FOR CARRYING OUT THE INVENTION The polymer used in the present invention is
Although not limited to, the solvent used for the electrolytic solution
Is generally highly polar, so polymers
It is preferable to select from those having high polarity. As the highly polar polymer, (a) poly
Unsaturation such as methyl acrylate and polymethyl methacrylate
Carboxylic acid ester polymer, polyacrylic acid, polymer
Unsaturated carboxylic acid polymers such as tacrylic acid, polyvinyl acetate
Vinyl polymers such as vinyl and polyvinyl alcohol, poly
Fluorine trees such as vinyl fluoride and polyvinylidene fluoride
Fats, polyacrylonitrile, polyvinylidene cyanide, etc.
Cyano group-containing polymer, polyvinyl chloride, polyvinyl chloride
By addition polymerization of halogen-containing polymers such as nilidene
The resulting polymer, (b) polyurethane, polyurea,
Polymers by polyaddition of polycarbonate, etc.
By polycondensation of ester, polyamide, polyimide, etc.
Polymers. Among these polymers,
Tylene unsaturated carboxylic acid ester or ethylenic
Monomers containing at least 70% by weight of unsaturated carboxylic acid
Polymer obtained has good electrolyte swelling performance
In addition to controlling polymer productivity and polymerization reaction
preferable. The ethylenically unsaturated carboxylic acid ester is
Selected from the compounds shown in the above description.1. Acrylic ester   Methyl acrylate, acrylic
Ethyl acrylate, propyl acrylate, isopropyl acrylate
, N-butyl acrylate, isobutyl acrylate,
N-Amyl acrylate, isoamyl acrylate, acrylic
N-hexyl acid, 2-ethylhexyl acrylate, and the like.2. Methacrylate   Methyl methacrylate, meth
Ethyl acrylate, propyl methacrylate, methacrylic acid
Isopropyl, n-butyl methacrylate, methacrylic acid
Isobutyl, n-amyl methacrylate, i-methacrylate
Soamyl, n-hexyl methacrylate, methacrylic acid 2
-Ethylhexyl and the like. [0014]3. Crotonic acid ester  Methyl crotonic acid
, Ethyl crotonate, propyl crotonate, croton
Butyl, isobutyl crotonate, n-amicrotonate
Isoamyl crotonate, n-hexyl crotonate,
2-ethylhexyl crotonate and the like.4. Other   Dimethylaminoethyl methacrylate, meth
Amino group-containing meta such as diethylaminoethyl acrylate
Crylate ester, methoxypolyethylene glycol
Methacrylic acid containing alkoxy group such as nomethacrylate
Steal and so on. Further, specific examples of the ethylenically unsaturated carboxylic acid
Examples are acrylic acid, methacrylic acid, crotonic acid, etc.
Of ethylenically unsaturated monocarboxylic acid monomers, male
Acid, fumaric acid, citraconic acid, mesaconic acid, glutaco
Acid, itaconic acid, crotonic acid, isocrotonic acid, etc.
Unsaturated dicarboxylic acid monomers and acid anhydrides
You. Among them, acrylic acid, methacrylic acid, etc.
Saturated monocarboxylic acids are preferred. These polymers are crosslinked
Having a structure prevents dissolution by the electrolyte
You. The cross-linked structure of the polymer has a cross-linking component
It is obtained by adding and polymerizing. During polymerization, the crosslinking component
Monomers having a functional group that gives a self-crosslinking structure after polymerization
Say ma. The molecular weight of the polymer is 10,000 to 5
000000, preferably 100000-100000
It is in the range of 0. Dissolves in electrolyte if molecular weight is too low
If the molecular weight is too high, the viscosity is too high.
Is difficult. The lithium salt of the electrolytic solution used in the present invention
As a specific example, LiPF₆, LiBF_Four, LiAsF
₆, LiClO_Four, LiSbF₆, LiI, LiBr,
LiCl, LiAlCl_Four, LiHF_Two, LiSCN,
CF_ThreeSO_ThreeLi, C_FourF_ThreeSO_ThreeLi, (CF_ThreeSO
_Two)_TwoNLi, (C_TwoF_FiveSO_Two)_TwoNLi, (CF _Three
SO_Two)_ThreeCLi, (C_FourF₉SO_Two)_TwoNLi, or
Are mixtures thereof. The solvent used for the electrolyte is as follows:
It is. Propylene carbonate, butylene carbonate
G, ethylene carbonate, diethyl carbonate,
Such as tyl ethyl carbonate and dimethyl carbonate
Organic carbonate, gamma-butyrolactone, propiola
Cuton, ethyl butyrate, butyl butyrate, propyl butyrate, professional
Aliphatic organic solvents such as ethyl pionate and butyl propionate
Stele, diglyme, tetrahydrofuran, diethyl ether
Organic ethers such as silicone oil
, Organic amines such as triethylamine, acetonitrile
Organic nitriles such as toluene and propionitrile, or
It contains at least a part of the mixture. these
Among them, propylene carbonate, ethylene carbonate
G, diethyl carbonate, methyl ethyl carbonate
, Organic solvents with high polarity such as dimethyl carbonate
Nate type is preferred in terms of battery performance. In the present invention, the polymer may be used in any form.
It can be inserted between the pond element and the exterior body. For example,
Make a thin film or flake of the rimer, and
Between the battery and the inside of the package,
There is also a method of performing direct bonding. Battery form of secondary battery
Is not particularly limited, cylindrical, square, thin square, card type,
It can be applied to any form such as coin type and sheet type.
You. In addition, winding structure, laminated structure,
It can be applied to battery elements of any structure. The positive electrode of the present invention
As the active material, occludes lithium ions electrochemically
Any known releasable can be used,
Above all, a material containing lithium is preferable. For example, general
Formula Li_XM_YN_ZO_Two(M is the transition metal element Co, N
selected from i, Fe, Mn, Cr, V, Ti, Cu
And at least one metal, N is Al, In, Sn,
At least one metal selected from B, 0 <X ≦
1.1, 0.5 <Y ≦ 1.0, Z ≦ 0.1)
Titanate composite metal oxides are preferred, and furthermore, the general formula Li
_XCo_YN_ZO_Two(Is N among Al, In, Sn, B?
At least one metal selected from the group consisting of 0 <X ≦ 1.1,
0.5 <Y ≦ 1.0, Z ≦ 0.1)
Tiums are more preferred. The above-mentioned positive electrode active material may be any of those known as conductive agents.
For example, activated carbon, various cokes, carbon black, etc.
Of non-graphitic carbonaceous materials and graphite
A material in which a specific conductive agent is mixed with a specific amount in an active material is used as a positive electrode.
At room temperature, the capacity retention of the room-temperature charge-discharge cycle characteristics is also high.
Can be done. That is, the average particle size is 1 to 25 μm.
100 parts by mass of a lithium acid composite metal oxide and the composite gold
The ratio of the average particle diameter to the average particle diameter of the group oxide is 0.2
Graphite powder having an aspect ratio (most preferable)
(Small projected area / maximum projected area) of 0.2 or less) 2
-10 parts by mass, relative to the average particle size of the composite metal oxide
Non-graphite whose average particle size ratio is 0.001 to 0.03
A mixture with 0.5 to 5 parts by mass of carbonaceous powder, or
1 of lithium acid composite metal oxide having an average particle size of 1 to 25 μm
00 parts by mass and a graphite powder having an average particle size of 3 μm or less (preferably
Or, after the pulverization,
) Is used as a positive electrode.
And non-aqueous system with high capacity retention rate at room temperature charge / discharge cycle characteristics
A secondary battery can be obtained. The positive electrode coating solution contains the positive electrode active material, the conductive agent,
It is obtained by mixing a solvent capable of dissolving the adhesive. Coating liquid solid
The concentration of the form is not particularly limited, but usually 30 mass
% To 80% by mass, preferably 40% to 70% by mass.
is there. The positive electrode coating liquid contains the positive electrode active material, the conductive agent, the binder,
Is dispersed in a dispersion medium. Coating liquid solids
The concentration is not particularly limited, but is usually 30 mass
% To 80% by mass, preferably 40% to 70% by mass.
is there. As a coating method of the positive electrode coating liquid, a die coater,
Reverse roll coater, comma bar coater, etc.
It can be applied to the current collector using a coating device. Positive electrode
Al, Cu, Ni, stainless steel
Metal foil or net with a thickness of about 8 to 100 μm
Etc. are used. In particular, metal foil or net made of Al
Preferably, it is used. The binder for the positive electrode is polyvinylidene fluoride
, Teflon (registered trademark), fluoro rubber, polyethylene
Rubber, nitrile rubber, polybutadiene, butyl rubber, steel
Len / butadiene rubber, styrene-butadiene copolymer,
Polysulfide rubber, nitrocellulose, cyanoethyl cellulose
A polymer such as water can be used. Also these
Polymer can be added to coating fluid as latex
Noh. Alternatively, acrylonitrile, vinyl fluoride
Chloroprene, hexafluoropropylene, tetra
Fluoroethylene, trifluoromonochloroethylene,
Fluoride with one or more of maleic anhydride
A copolymer with vinylidene can also be used. Special
Polyvinylidene fluoride, Tef
Ron, or fluorine rubber. Next, a carbon material is used as the negative electrode active material of the present invention.
Material, amorphous alloy, amorphous metal oxide, amo
Can absorb and release lithium such as rufus metal nitride
Materials can be used, but carbon materials are particularly preferred.
No. Here, the carbon material is a material mainly composed of carbon.
Refers to graphite and graphitic materials, coke, graphite and coke
Hybrid material, graphitized or carbonized carbon fiber
Fiber, carbon black, acetylene black, graphitized
Or carbonized meso-micro carbon beads, carbon
Whisker, carbonized non-graphitizable carbon, fired resin
Can be raised. Cu, Ni, silver
6 ~ 100μm thick gold such as stainless steel
A metal foil or a net is used. As the binder for the negative electrode, polyvinylidene fluoride
, Teflon, fluoro rubber, polyethylene, nitrile
Rubber, polybutadiene, butyl rubber, styrene / butadiene
Rubber, styrene butadiene latex, polysulfide rubber,
Nitrocellulose, cyanoethylcellulose, and the above
Latex of various compositions, acrylonitrile, vinyl fluoride
Chloroprene, hexafluoropropylene, tetra
Fluoroethylene, trifluoromonochloroethylene,
Fluoride with one or more of maleic anhydride
A copolymer with vinylidene or the like is used. Especially preferred
Styrene / butadiene rubber, styrene
Butadiene latex, polyvinylidene fluoride, anhydrous
One or more of maleic acid and vinylidene fluoride
And a copolymer with den. These materials are used as electrodes
The processing method used is the same as for the positive electrode.
Law is available. In order to prevent a short circuit between the positive electrode and the negative electrode,
A separator can be provided between the anode and the negative electrode. This section
Examples of parators include polyethylene and polypropylene.
For porous sheets and non-woven fabrics of materials such as cellulose and cellulose
You can. In the present invention, the battery form of the secondary battery is particularly
Not limited, cylindrical type, square type, thin square type, card type, coin
It can be applied to any form such as a mold and a sheet mold. Ma
Such as rolled, laminated, and folded structures
It can also be applied to an electrode having a different structure. Now, the present invention will be described in further detail with reference to Examples.
explain. EXAMPLES (Example 1) Lithium hydroxide as a positive electrode active material
And cobalt hydroxide, mixed at 800 ℃ in air
Heat for 8 hours to produce LiCoO_TwoWas synthesized. This LiCo
O_TwoFor 100 parts by mass, a conductive agent having an average particle size of 3 μm
2.5 parts by mass of graphite having an average particle size of 0.04 μm
2.5 parts by weight of non-graphite carbonaceous powder of
Undone. For 100 parts by weight of this compound
And polyvinylidene fluoride polymer (Kureha)
4 parts by mass of KF polymer # 1100 (manufactured by Chemical Industry)
-Methyl-2-pyrrolidone, and after dispersion,
A positive electrode coating liquid having a shape fraction of 65% by mass was obtained. Thick this coating liquid
A coating amount of 260 ± 3 on both sides of a 15 μm aluminum foil
g / m^TwoAfter coating and drying so that it becomes
The active material has a bulk density of 2.9 ± 0.3 g / cm^ThreeSo that
Pressed. On the other hand, natural graphite: BF-
15SP (manufactured by Chuetsu Graphite Industry Co., Ltd.) 100 parts by mass
On the other hand, 50 wt% of styrene and 50 wt% of butadiene
Latex containing polymer polymerized by composition
2 parts by weight, 1.5 parts by weight of carboxymethyl cellulose
Parts, and the dispersion medium is water, and the solid content concentration is 40.
% By mass of the negative electrode coating liquid. This is a 12μm thick copper foil
Coating amount on both sides of 93 ± 3g / m^TwoCoated dry to become
After drying, the bulk density of the active material is 1.3 ± with a roll press.
0.3g / cm^ThreePressing was performed so that More than
The width of the positive electrode and the negative electrode manufactured as described above was 50 mm and the length was 25.
After welding each tab to the one cut to cm, thickness
Through a 25 μm polyethylene microporous membrane separator
To make a coil with a cylindrical core with a diameter of about 19 mm
did. With a hot press machine that heated this coil to 80 ° C
Press forming with a load of 3000N for 60 seconds to make it flat
Was. As a polymer to be added to the exterior body,
Copolymer of rilonitrile and methyl acrylate at a mixing ratio of 9: 1
A thin film having a thickness of 50 μm by the coalescence was produced. continue,
Approximately 3.2mm deep, 35mm wide and 55mm high
Bag-shaped aluminum with a cup-shaped uneven part with different dimensions
(Laminate foil)
Coil). In this case, add
Acrylonitrile and acrylic acid
The copolymer of methyl is represented by the formula (1) (Wp × SWp) /
(We-ρs × Vcal) only for the mass at which the value becomes 0.5
Cut out the flat surface of the exterior body and coil together with the coil
Inserted between the positions. This bag-shaped lamine molded into a bag
LiBF inside the heat film_FourTo 1.5 mol / l
Ethylene carbonate, gamma butyrolact
About 2.6 g of a 1: 1 electrolyte solution in a volume ratio of
Seal the bag-like laminated film while reducing the pressure to 00Pa.
The battery as shown in FIG. 1 was manufactured. Added to batteries
Swelling of copolymer of acrylonitrile and methyl acrylate
The degree was 6.2. This battery was placed in a thermostat at 20 ° C. for one cycle.
4.2V constant potential (positive / negative) after 0.5C constant current
After charging for 8 hours at 3.0 C with a constant current of 0.5 C.
The battery was discharged to a potential of V, and charge and discharge characteristics were evaluated. here
1.0C means that electricity in a fully charged state can be discharged in one hour
1.0 C of this battery is equivalent to 700 mA.
Hit. After the first charge / discharge, the battery
Approximately 3mm × at two corners of the laminated film
After making a 3mm hole, place this battery in a metal container and
Rotation processing at 2000 rpm for 30 minutes with a core separator
The mass loss before and after was very small amount of 0.013g
there were. From this result, it is confirmed that the liquid leakage resistance is very good.
I understood. A first charge / discharge operation was performed on a battery manufactured in the same manner.
Afterwards, constant current at 1.0 C and 4.2 V in a constant temperature bath at 20 ° C.
After charging for 3 hours by the constant voltage method, 3.0 V at 1.0 C
The cycle of discharging until 100 times was repeated 100 times. At this time,
Cycle characteristics at 100 cycles indicated by the following equation
Was 90.5%, which was a good result. Cycle characteristics at 100 cycles (%) = [(10
(0th cycle discharge amount) / (2nd cycle discharge amount)]
× 100 (Embodiments 2 and 3)
A thin film of a copolymer of lonitrile and methyl acrylate is represented by the formula
(1) (Wp × SWp) / (We−ρs × Vcal)
Cut out the value so that it becomes the value shown in Table 1, and coil
Together with the coil at the position between the flat body and the coil.
A battery was prepared and evaluated in the same manner as in Example 1 except for
Was. As shown in Table 1, all of the obtained batteries had good leakage.
It showed liquid resistance and cycle characteristics. (Examples 4 to 6) With acrylonitrile in Example 1
Instead of the methyl acrylate copolymer,
Thickness due to copolymer of chill and methacrylic acid at a mixing ratio of 9: 1
A thin film having a thickness of 50 μm was prepared, and (Wp × SW)
p) / (We-ρs × Vcal) is equal to the value shown in Table 1.
So that the outer body and coil
Same as Example 1 except that it is inserted between the flat surfaces
A battery was prepared and evaluated. The batteries obtained are listed in Table 1.
As shown, all of them show good liquid leakage resistance and cycle characteristics.
did. Ethyl acrylate and methacrylic acid added to the battery
The degree of swelling of the copolymer was 11.4. (Embodiments 7 to 9)
Instead of a copolymer of lonitrile and methyl acrylate,
Mixing ratio of vinylidene fluoride and propylene hexafluoride of 8: 2
A thin film having a thickness of 50 μm was prepared from the copolymer
(1) (Wp × SWp) / (We−ρs × Vcal)
Cut out the value so that it becomes the value shown in Table 1, and
Both were inserted in the position between the outer surface and the flat surface of the coil
Except for the above, a battery was prepared and evaluated in the same manner as in Example 1.
As shown in Table 1, all of the obtained batteries had good resistance to liquid leakage.
Properties and cycle characteristics. Vinylilium fluoride added to batteries
The swelling degree of the copolymer of den and hexafluoropropylene is 1.5
It was 4. (Comparative Example 1)
Do not add any polymer when inserting the
A battery was fabricated and evaluated in the same manner as in Example 1 except for the fabrication.
became. The obtained battery has good cyclability of 90.4%.
However, in the liquid leakage test, the mass loss of 0.498 g
It was confirmed that the liquid leakage resistance was significantly inferior. (Comparative Examples 2 and 3) Acrylonitrile in Example 1
A thin film of a copolymer of methyl acrylate was formed by coating (W) of the formula (1).
The value of (p × SWp) / (We−ρs × Vcal) is shown in Table 1.
Cut out to the value of
Example except that it was inserted between the flat surfaces of the coil
A battery was prepared and evaluated in the same manner as in Example 1. Battery obtained
Indicates a decrease in liquid leakage resistance or cycle characteristics as shown in Table 1.
I showed you. (Comparative Examples 4 and 5)
Instead of a copolymer of lonitrile and methyl acrylate,
A mixture of ethyl acrylate and methacrylic acid at a mixing ratio of 9: 1
A thin film having a thickness of 50 μm is formed by the unification, and
Table 1 shows the value of (Wp × SWp) / (We−ρs × Vcal).
And cut out to the value described in
Other than inserted between the body and the flat surface of the coil.
A battery was prepared and evaluated in the same manner as in Example 1. Got
Batteries have leakage resistance or cycle characteristics as shown in Table 1.
It was shown to decrease. (Comparative Examples 6 and 7) Acrylonitrile in Example 1
Instead of methyl acrylate copolymer,
To a copolymer of propylene and hexafluorofluoride in a mixing ratio of 8: 2
A thin film having a thickness of 50 μm according to formula (1)
× SWp) / (We-ρs × Vcal) are shown in Table 1.
And cut it together with the coil to the exterior body.
Example 1 except that it was inserted at a position between the flat surfaces of the
A battery was prepared and evaluated in the same manner as described above. The resulting battery is
As shown in Table 1, the resistance to liquid leakage or cycle characteristics is reduced.
It was shown that. [0034] [Table 1][0035] As described above, according to the present invention, the battery
Add the amount of polymer that satisfies the above formula inside the package.
Non-water with better liquid leakage resistance and cycleability
An electrolyte secondary battery can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a battery produced by inserting a positive / negative coil into a laminated film having a cup-shaped uneven portion, filling an electrolyte and closing the container under reduced pressure. [Description of Signs] 1 Battery 2 Laminated film 3 Positive electrode tab 4 Negative electrode tab

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Tomoko Shimoyamada             1-3-1 Night Light, Kawasaki-ku, Kawasaki-shi, Kanagawa               Asahi Kasei Corporation F term (reference) 5H029 AJ14 AJ15 AK03 AL07 AL08                       AM03 AM04 AM05 AM07 AM16                       BJ04 DJ01 DJ02 DJ03 DJ06                       HJ00 HJ01 HJ07

Claims (1)

Claims: 1. A secondary battery in which a battery element and an electrolyte, which are capable of charging and discharging a positive electrode and a negative electrode facing each other with a separator interposed therebetween, are housed in a battery outer package. A non-aqueous secondary battery, characterized in that the internal space of the battery exterior except for the polymer contains an amount of a polymer satisfying the following formula (1). 0.2 ≦ (Wp × SWp) / (We−ρs × Vcal) ≦ 1.0 (1) Wp: mass of polymer SWp: degree of swelling of polymer We: mass of total electrolyte solution injected into battery ρs: Specific gravity of electrolyte Vcal: Total volume of voids in positive electrode, negative electrode and separator