CA2294292C - Solid electrolyte secondary battery - Google Patents
Solid electrolyte secondary battery Download PDFInfo
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- CA2294292C CA2294292C CA002294292A CA2294292A CA2294292C CA 2294292 C CA2294292 C CA 2294292C CA 002294292 A CA002294292 A CA 002294292A CA 2294292 A CA2294292 A CA 2294292A CA 2294292 C CA2294292 C CA 2294292C
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Dispersion Chemistry (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Silicates, Zeolites, And Molecular Sieves (AREA)
- Compositions Of Oxide Ceramics (AREA)
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- Graft Or Block Polymers (AREA)
Abstract
A solid electrolytic secondary battery comprising a positive electrode, a negative electrode and a solid electrolyte interposed between the electrodes, wherein the solid electrolyte contains, as a matrix polymer, a block copolymer of vinylidene fluoride and hexafluoropropylene. The membrane of the block copolymer has a strong mechanical toughness and a high solvent retaining capability and, when used as a matrix polymer of the solid electrolyte, significantly improves an adhesion strength, load characteristics and low-temperature characteristics. A constitutional ratio of hexafluoropropylene in the block copolymer is preferably 3 to 7.5 wt.% with a molecular weight of not smaller than 550,000 and a copolymer having a weight-average molecular weight (Mw) of not smaller than 300,000 and smaller than 550,000 may be jointly used.
Description
DESCRIPTION
Solid Electrolyte Secondary Battery Technical Field The present invention relates to a solid-electrolyte secondary battery having a solid electrolyte (also a gel electrolyte) disposed therein between a positive electrode and negative electrode, and more particularly, to a novel solid-electrolyte secondary battery improved in charge and discharge cycle life, volumetric energy density, load characteristic at low temperature, productivity, etc.
Background Art In recent years, many portable electronic apparatuses such as an integral VTR/video camera unit, portable telephone, portable computer, etc. have been proposed, and they show a tendency to be more and more compact for their unproved portability. Many developments and researches have been made to provide a thinner or bendable battery, more specifically, a secondary battery, or a lithium ion battery among others, for use as a portable power source in such a more compact portable electronic apparatus.
To attain such a thinner or bendable battery structure, active researches have been made concerning a solidified electrolyte for use in the battery.
Especially, a gel electrolyte containing a plasticizer and a polyineric solid electrolyte made froin a high inolecular material having lithium salt dissolved therein are attracting much attention from many fields of industry.
Solid Electrolyte Secondary Battery Technical Field The present invention relates to a solid-electrolyte secondary battery having a solid electrolyte (also a gel electrolyte) disposed therein between a positive electrode and negative electrode, and more particularly, to a novel solid-electrolyte secondary battery improved in charge and discharge cycle life, volumetric energy density, load characteristic at low temperature, productivity, etc.
Background Art In recent years, many portable electronic apparatuses such as an integral VTR/video camera unit, portable telephone, portable computer, etc. have been proposed, and they show a tendency to be more and more compact for their unproved portability. Many developments and researches have been made to provide a thinner or bendable battery, more specifically, a secondary battery, or a lithium ion battery among others, for use as a portable power source in such a more compact portable electronic apparatus.
To attain such a thinner or bendable battery structure, active researches have been made concerning a solidified electrolyte for use in the battery.
Especially, a gel electrolyte containing a plasticizer and a polyineric solid electrolyte made froin a high inolecular material having lithium salt dissolved therein are attracting much attention from many fields of industry.
2 As the high molecular materials usable to produce a high molecular solid electrolyte, a silicone gel, acryl gel, acrylonitrile, polyphosphazen-modified polyiner, polyethylene oxide, polypropylene oxide, their composite polymer, cross-linked polyiner, modified polylner, etc. have been reported. In the conventional secondary battery using a solid electrolyte made from one of these high molecular materials, however, since the electrolyte film has no sufficient fihn strength and adhesion to the battery electrodes, there occurs a nonuniformity between the charge and discharge currents, and a lithium dendrite easily takes place. Thus, the conventional secondary battery has a short charge and discharge cycle life (number of charge and discharge cycles), namely, it is critically disadvantageous in that it cannot meet the requirement "stable usability for a longer term" being one of the basic and ilnportant requirements for production of a colninercial article.
Further, for a higher film strength of a solid electrolyte, it has been proposed to cross-link a trifunctional polyethylene glycol and diisocyanate derivative by reaction between them (as disclosed in the Japanese Unexalnined Patent Publication No.
48716) or to cross-link polyethylene glycol diacrylate by polylnerization (as disclosed in the Japanese Unexainined Patent Publication No. 62-285954). Because an unreacted substance or a solvent used for the reaction remains, the electrolyte has no sufficient adhesion to the battery electrodes. Moreover, the indispensable process of drying removal causes the productivity to be low. These methods are required for a further iunprovelnent.
~
As mentioned above, the high molecular solid or gel electrolyte has excellent characteristics not found with the liquid electrolytes, but when it is used in a battery, it can hardly be put in ideal contact with the battery electrodes. This is because the solid or gel electrolyte will not flow as the liquid electrolyte.
The contact of the high molecular solid or gel electrolyte with the battery electrodes has a large influence on the battery performance. Nalnely, if the contact between them is poor, the contact resistance between the high molecular solid or gel electrolyte and the battery electrodes is large so that the internal resistance of the battery is large. Furthennore, there cannot be an ideal ion movement between the high molecular solid or gel electrolyte and the electrodes, and so the battery capacity is also low. If such a battery is used for a long tenn, there occurs a nonunifonnity between the charge and discharge currents and a lithium dendrite is likely to take place.
Therefore, in a battery using a high molecular solid or gel electrolyte, it is extremely ilnportant to adhere the high molecular solid or gel electrolyte to active material layers of electrodes of the battery with a sufficient adhesive strength.
To implement the above, it has been proposed as in the Japanese Unexamined Patent Publication No. 2-40867 to use a positive electrode composite in which a high molecular solid electrolyte is added to a positive active material layer of the positive electrode. In the battery disclosed in the Japanese Unexamined Patent Publication, a part of the high inolecular solid electrolyte is mixed in the positive active material layer to improve the electrical contact between the high molecular solid electrolyte and positive-electrode active material layer.
However, in case the method disclosed in the Japanese Unexainined Patent Publication No. 2-40867 is adopted, the positive-electrode composite to which the high molecular solid electrolyte is added must be used to produce a positive plate and the high inolecular solid electrolyte should be laininated on the positive plate.
No ideal contact can be attained between the positive plate and solid electrolyte. More specifically, if a solid electrolyte having an irregular surface is laininated on an electrode layer, no good adhesion between them can be ensured and the internal resistance will be increased, with a result that the load cllaracteristic becomes worse.
Atso, a positive or negative electrode composite in which a high molecular solid or gel electrolyte is added cannot easily be pressed to a sufficient extent because of the elasticity of the high molecular solid or gel electrolyte, and the grain spacing inside the composite is large, with a result that the internal resistance is increased.
Also in this case, the load characteristic becomes worse. Furthennore, to prevent an electrolyte salt contained in the high molecular solid or gel electrolyte from being dissolved, the positive or negative electrode should be produced at a low humidity, their quality cannot easily be controlled, and the manufacturing costs are large.
Also, it has been proposed to use a copolyiner produced by copolymerization of 8 to 25 % by weight of hexafluoroethylene with the fluorocarbon polymer in order to improve the load perfonnance and low- temperature perfonnance. However, the addition of the hexafluoroethylene in such an amount will lower the crystallization temperature of the polylner, thus resulting in a deteriorated fihn strength.
Thus, the action to isolate the positive and negative electrodes from each other is considerably decreased. If the fihn thickness is not as large as 100 in or so, a short-circuit will arise between the electrodes. Such a large film thickness will not provide a necessary volumetric energy density for the battery as a coinmercial article.
Therefore to reduce the fihn thickness for a desired volumetric energy density, a third means for reinforcing the fihn strength should be used, which will add to the manufacturing labor and costs.
For the salne reason, the lnaxilnuzn alnount of an electrolyte is 70 % by weight.
If a large alnount is added, the electrolyte cannot keep the fonn of a film but it will take the fonn of a sol. This will be the perfonnance linut of the battery and it is difficult to ensure a sufficient load perfonnance and low-temperature perfonnance.
Disclosure of the Invention Accordingly, the present invention has an object to overcome the above-mentioned drawbacks of the prior art by providing a solid electrolyte excellent in adhesion to the active material layers of the electrodes, and thus providing a solid-electrolyte secondary battery using therein the solid electrolyte to ensure a good electrical contact between the solid electrolyte and active material layers of a positive electrode and negative electrode of the battery.
Also, the present invention has another object to provide a solid-electrolyte secondary battery having an improved charge and discharge cycle life and excellent in load characteristic, low-teznperature perfonnance and productivity.
To attain the above object, the Inventors have been made many researches for a long tenn. As a result of the researches, it has been found that the molecular structure of a fluorocarbon polyiner used as a matrix polymer in the solid electrolyte has a great influence on the characteristics of the electrolyte, use of a vinylidene fluoride/hexafluoropropylene block copolyiner makes it possible to adhere the high molecular solid or gel electrolyte with a sufficient adhesive strength to the active material layers of the electrodes, provide a good electrical contact between the solid or gel electrolyte and the active material of the positive and negative electrodes and ensure a sufficient fi.hn strength, and thus provide a solid-electrolyte secondary battery having a longer charge and discharge cycle life and excellent in load characteristic, low-teinperature perfonnance and productivity.
The solid-electrolyte secondary battery according to the present invention is coinpleted based on the above findings by the Inventors and comprises a positive electrode and negative electrode and a solid electrolyte provided between the electrodes, the solid electrolyte containing as a matrix polymer a vinylidene fluoride/hexafluoropropylene block copolyiner.
Note that the tenn "solid electrolyte" used herein refers to a so-called solid electrolyte as well as to a gel electrolyte in which a matrix polyiner is plasticized by a plasticizer, for exainple. Therefore, the solid-electrolyte secondary battery of the present invention includes a gel-electrolyte secondary battery as well. The solid-electrolyte comprises an electrolytic solution in proportion of 80% or more.
The present invention is essentially characterized in that a vinylidene fluoride/hexafluoropropylene block copolymer is used as a matrix polyiner. The block copolylner assures an excellent adhesion of the electrolyte to the active material layers of positive and negative electrodes, and the properties of the individual monomers assure a sufficient toughness and solvent retention in combination. Therefore, it is possible to adhere the high molecular solid or gel electrolyte to the active material of the electrodes with a sufficient adhesive strength, retain a large amount of solvent (electrolyte) while maintaining a high film strength, and ilnplement an unproved charge and discharge cycle life, load characteristic and low-temperature perfonnance.
These objects and other objects, features and advantages of the present intention will become more apparent from the following detailed description of the preferred elnbodilnents of the present invention when taken in conjunction with the accompanying drawings.
Brief Description of the Drawings FIG. I shows a characteristic curve of the correlation between weight-average molecular weight (Mw), number-average molecular weight (Mn) and logarithlnic viscosity nuinber (dl/g);
FIG. 2 is a sectional view of an experilnental battery of the present invention;
and FIG. 3 is also a sectional view of the peel test equipment.
Best Mode For Canying Out the Invention The solid-electrolyte secondary battery according to the present invention uses as a matrix polymer a vinylidene fluoride/hexafluoropropylene block copolyiner.
In a vinylidene fluoride/hexafluoropropylene copolymer synthesized to have a molecular weight equivalent to that of a polyvinylidene fluoride having a melting point of 175 C as measured by a DSC (differential scanning calorimeter), a simple random polymerization will result in a combination of the crystallinity of the vinylidene fluoride and flexibility of the hexafluoropropylene and the melting point will be 130 to 140 C as in the case when the crystallinity is lower.
However, the block copolyiner reflects the properties of the individual monomers. For example, the crystallization by the vinylidene fluoride, for example, will not unpaix that of the block copolyiner, and the melting point of the block copolyiner is 150 C or so which is near a iniddle point between the melting points of the respective monomers. Siunilarly, the flexibility of the hexafluoropropylene is maintained in the block copolyiner. ' Thus, the block copolymer will keep a sufficient toughness owing to the crystallinity of the vinylidene fluoride and also a sufficient flexibility owing to that of the hexafluoropropylene.
Siinilarly, concerning the solvent (electrolyte) retention, the random polymerization provides only an iunprovement in solvent retention for a reduced crystallization point. If it is tried by such a random polymerization to retain a larger ainount of solvent by using more than 8% by weight of the hexafluoropropylene, the filin strength is considerably reduced, resulting in a sol state, so that the random polymer cannot keep its function as a solid or gel electrolyte.
The block copolymer keeps a sufficient toughness owing to the crystallinity, so that a high fihn strength can be lnaintained while large amount of solvent (electrolyte) is being retained. Even with a ratio, not so high, of the hexafluoropropylene, the block copolymer keeps a high solvent retaining capability.
The solid-electrolyte secondary battery according to the present invention shows an excellent load characteristic and low-teliiperature performance since the solid electrolyte can retain a large alnount of solvent while maintaining a high film strength.
The proportion of hexafluoropropylene in the block copolylner may a one while will assure a necessary solvent retention and preferably within a range of 3 to 7.5 %
by weight. If the proportion of hexafluoropropylene is higher, the filln strength may possibly be insufficient. If the proportion is under 3% by weight, the effect of ilnprovelnent in solvent retaining capability due to the copolylnerization of hexafluoropropylene will be insufficient so that no sufficient ainount of solvent (electrolyte) can be retained.
The block copolyiner used as the matrix polymer should have a weight-average molecular weight of 550,000 or more. If the block copolylner has a weight-average molecular weight of under 550,000, it may possibly provide no sufficient adhesive strength. Note that as the block copolylner has a weight-average molecular weight increased from 300,000, it has a gradually increased adhesive strength.
However, the adhesive strength assured by a weight-average molecular weight under 550,000 cannot always be said to be sufficient. To ensure a sufficient adhesive strength, the weight-average molecular weight (Mw) should be over 550,000.
The block copolymer should desirably have a weight-average molecular weight of more than 550,000; however, for a weight-average molecular weight of more than
Further, for a higher film strength of a solid electrolyte, it has been proposed to cross-link a trifunctional polyethylene glycol and diisocyanate derivative by reaction between them (as disclosed in the Japanese Unexalnined Patent Publication No.
48716) or to cross-link polyethylene glycol diacrylate by polylnerization (as disclosed in the Japanese Unexainined Patent Publication No. 62-285954). Because an unreacted substance or a solvent used for the reaction remains, the electrolyte has no sufficient adhesion to the battery electrodes. Moreover, the indispensable process of drying removal causes the productivity to be low. These methods are required for a further iunprovelnent.
~
As mentioned above, the high molecular solid or gel electrolyte has excellent characteristics not found with the liquid electrolytes, but when it is used in a battery, it can hardly be put in ideal contact with the battery electrodes. This is because the solid or gel electrolyte will not flow as the liquid electrolyte.
The contact of the high molecular solid or gel electrolyte with the battery electrodes has a large influence on the battery performance. Nalnely, if the contact between them is poor, the contact resistance between the high molecular solid or gel electrolyte and the battery electrodes is large so that the internal resistance of the battery is large. Furthennore, there cannot be an ideal ion movement between the high molecular solid or gel electrolyte and the electrodes, and so the battery capacity is also low. If such a battery is used for a long tenn, there occurs a nonunifonnity between the charge and discharge currents and a lithium dendrite is likely to take place.
Therefore, in a battery using a high molecular solid or gel electrolyte, it is extremely ilnportant to adhere the high molecular solid or gel electrolyte to active material layers of electrodes of the battery with a sufficient adhesive strength.
To implement the above, it has been proposed as in the Japanese Unexamined Patent Publication No. 2-40867 to use a positive electrode composite in which a high molecular solid electrolyte is added to a positive active material layer of the positive electrode. In the battery disclosed in the Japanese Unexamined Patent Publication, a part of the high inolecular solid electrolyte is mixed in the positive active material layer to improve the electrical contact between the high molecular solid electrolyte and positive-electrode active material layer.
However, in case the method disclosed in the Japanese Unexainined Patent Publication No. 2-40867 is adopted, the positive-electrode composite to which the high molecular solid electrolyte is added must be used to produce a positive plate and the high inolecular solid electrolyte should be laininated on the positive plate.
No ideal contact can be attained between the positive plate and solid electrolyte. More specifically, if a solid electrolyte having an irregular surface is laininated on an electrode layer, no good adhesion between them can be ensured and the internal resistance will be increased, with a result that the load cllaracteristic becomes worse.
Atso, a positive or negative electrode composite in which a high molecular solid or gel electrolyte is added cannot easily be pressed to a sufficient extent because of the elasticity of the high molecular solid or gel electrolyte, and the grain spacing inside the composite is large, with a result that the internal resistance is increased.
Also in this case, the load characteristic becomes worse. Furthennore, to prevent an electrolyte salt contained in the high molecular solid or gel electrolyte from being dissolved, the positive or negative electrode should be produced at a low humidity, their quality cannot easily be controlled, and the manufacturing costs are large.
Also, it has been proposed to use a copolyiner produced by copolymerization of 8 to 25 % by weight of hexafluoroethylene with the fluorocarbon polymer in order to improve the load perfonnance and low- temperature perfonnance. However, the addition of the hexafluoroethylene in such an amount will lower the crystallization temperature of the polylner, thus resulting in a deteriorated fihn strength.
Thus, the action to isolate the positive and negative electrodes from each other is considerably decreased. If the fihn thickness is not as large as 100 in or so, a short-circuit will arise between the electrodes. Such a large film thickness will not provide a necessary volumetric energy density for the battery as a coinmercial article.
Therefore to reduce the fihn thickness for a desired volumetric energy density, a third means for reinforcing the fihn strength should be used, which will add to the manufacturing labor and costs.
For the salne reason, the lnaxilnuzn alnount of an electrolyte is 70 % by weight.
If a large alnount is added, the electrolyte cannot keep the fonn of a film but it will take the fonn of a sol. This will be the perfonnance linut of the battery and it is difficult to ensure a sufficient load perfonnance and low-temperature perfonnance.
Disclosure of the Invention Accordingly, the present invention has an object to overcome the above-mentioned drawbacks of the prior art by providing a solid electrolyte excellent in adhesion to the active material layers of the electrodes, and thus providing a solid-electrolyte secondary battery using therein the solid electrolyte to ensure a good electrical contact between the solid electrolyte and active material layers of a positive electrode and negative electrode of the battery.
Also, the present invention has another object to provide a solid-electrolyte secondary battery having an improved charge and discharge cycle life and excellent in load characteristic, low-teznperature perfonnance and productivity.
To attain the above object, the Inventors have been made many researches for a long tenn. As a result of the researches, it has been found that the molecular structure of a fluorocarbon polyiner used as a matrix polymer in the solid electrolyte has a great influence on the characteristics of the electrolyte, use of a vinylidene fluoride/hexafluoropropylene block copolyiner makes it possible to adhere the high molecular solid or gel electrolyte with a sufficient adhesive strength to the active material layers of the electrodes, provide a good electrical contact between the solid or gel electrolyte and the active material of the positive and negative electrodes and ensure a sufficient fi.hn strength, and thus provide a solid-electrolyte secondary battery having a longer charge and discharge cycle life and excellent in load characteristic, low-teinperature perfonnance and productivity.
The solid-electrolyte secondary battery according to the present invention is coinpleted based on the above findings by the Inventors and comprises a positive electrode and negative electrode and a solid electrolyte provided between the electrodes, the solid electrolyte containing as a matrix polymer a vinylidene fluoride/hexafluoropropylene block copolyiner.
Note that the tenn "solid electrolyte" used herein refers to a so-called solid electrolyte as well as to a gel electrolyte in which a matrix polyiner is plasticized by a plasticizer, for exainple. Therefore, the solid-electrolyte secondary battery of the present invention includes a gel-electrolyte secondary battery as well. The solid-electrolyte comprises an electrolytic solution in proportion of 80% or more.
The present invention is essentially characterized in that a vinylidene fluoride/hexafluoropropylene block copolymer is used as a matrix polyiner. The block copolylner assures an excellent adhesion of the electrolyte to the active material layers of positive and negative electrodes, and the properties of the individual monomers assure a sufficient toughness and solvent retention in combination. Therefore, it is possible to adhere the high molecular solid or gel electrolyte to the active material of the electrodes with a sufficient adhesive strength, retain a large amount of solvent (electrolyte) while maintaining a high film strength, and ilnplement an unproved charge and discharge cycle life, load characteristic and low-temperature perfonnance.
These objects and other objects, features and advantages of the present intention will become more apparent from the following detailed description of the preferred elnbodilnents of the present invention when taken in conjunction with the accompanying drawings.
Brief Description of the Drawings FIG. I shows a characteristic curve of the correlation between weight-average molecular weight (Mw), number-average molecular weight (Mn) and logarithlnic viscosity nuinber (dl/g);
FIG. 2 is a sectional view of an experilnental battery of the present invention;
and FIG. 3 is also a sectional view of the peel test equipment.
Best Mode For Canying Out the Invention The solid-electrolyte secondary battery according to the present invention uses as a matrix polymer a vinylidene fluoride/hexafluoropropylene block copolyiner.
In a vinylidene fluoride/hexafluoropropylene copolymer synthesized to have a molecular weight equivalent to that of a polyvinylidene fluoride having a melting point of 175 C as measured by a DSC (differential scanning calorimeter), a simple random polymerization will result in a combination of the crystallinity of the vinylidene fluoride and flexibility of the hexafluoropropylene and the melting point will be 130 to 140 C as in the case when the crystallinity is lower.
However, the block copolyiner reflects the properties of the individual monomers. For example, the crystallization by the vinylidene fluoride, for example, will not unpaix that of the block copolyiner, and the melting point of the block copolyiner is 150 C or so which is near a iniddle point between the melting points of the respective monomers. Siunilarly, the flexibility of the hexafluoropropylene is maintained in the block copolyiner. ' Thus, the block copolymer will keep a sufficient toughness owing to the crystallinity of the vinylidene fluoride and also a sufficient flexibility owing to that of the hexafluoropropylene.
Siinilarly, concerning the solvent (electrolyte) retention, the random polymerization provides only an iunprovement in solvent retention for a reduced crystallization point. If it is tried by such a random polymerization to retain a larger ainount of solvent by using more than 8% by weight of the hexafluoropropylene, the filin strength is considerably reduced, resulting in a sol state, so that the random polymer cannot keep its function as a solid or gel electrolyte.
The block copolymer keeps a sufficient toughness owing to the crystallinity, so that a high fihn strength can be lnaintained while large amount of solvent (electrolyte) is being retained. Even with a ratio, not so high, of the hexafluoropropylene, the block copolymer keeps a high solvent retaining capability.
The solid-electrolyte secondary battery according to the present invention shows an excellent load characteristic and low-teliiperature performance since the solid electrolyte can retain a large alnount of solvent while maintaining a high film strength.
The proportion of hexafluoropropylene in the block copolylner may a one while will assure a necessary solvent retention and preferably within a range of 3 to 7.5 %
by weight. If the proportion of hexafluoropropylene is higher, the filln strength may possibly be insufficient. If the proportion is under 3% by weight, the effect of ilnprovelnent in solvent retaining capability due to the copolylnerization of hexafluoropropylene will be insufficient so that no sufficient ainount of solvent (electrolyte) can be retained.
The block copolyiner used as the matrix polymer should have a weight-average molecular weight of 550,000 or more. If the block copolylner has a weight-average molecular weight of under 550,000, it may possibly provide no sufficient adhesive strength. Note that as the block copolylner has a weight-average molecular weight increased from 300,000, it has a gradually increased adhesive strength.
However, the adhesive strength assured by a weight-average molecular weight under 550,000 cannot always be said to be sufficient. To ensure a sufficient adhesive strength, the weight-average molecular weight (Mw) should be over 550,000.
The block copolymer should desirably have a weight-average molecular weight of more than 550,000; however, for a weight-average molecular weight of more than
3,000,000, the polymer ratio has to be lowered to an impractical dilution ratio. The solid or gel electrolyte is produced by using, singly or as a component of the plasticizer, one of esters, ethers or carbonates usable in a battery to prepare a solution of the high molecular compound, electrolyte salt and solvent (and further a plasticizer for a gel electrolyte), unpregnating the solution into a positive or negative electrode active material, and removing the solvent to solidify the electrolyte.
Therefore, the esters, ethers or carbonates usable in the battery are limited of thelnselves.
The esters, ethers or carbonates included in the lunited range and having a weight-average molecular weight of more than 1,000,000 do not show a sufficient solubility to prepare a suitable solution.
Therefore, the weight-average molecular weight (Mw) of the block copolylner should preferably range from 550,000 to 3,000,000, and more preferably from 550,000 to 1,000,000.
In case a block copolylner of 550,000 or more in weight-average molecular weight (Mw) is used, another fluorocarbon of over 300,000 and under 550,000 in Mw may be used in combination to lower the viscosity for facilitating to fonn a film of the electrolyte. In this case, however, the ratio of the block copolylner of 550,000 or more in Mw should preferably be 30 % or more by weight. If the ratio of the block copolymer of 550,000 or more in Mw is lower, it will be difficult to ensure an intended sufficient adhesive strength of the solid electrolyte.
The block copolyiner of 550,000 or more in Mw is prepared by using a peroxide and polymerizing a monomer at a temperature ranging from room temperature to 200 C and under an atsnospheric pressure of 300 or less. It is industrially produced by the suspension polymerization or emulsion polyinerization process.
In the suspension polyznerization process, water is used as a medium, a dispersant is added to the monomer to disperse the latter as liquid drops into the medium, the organic peroxide dissolved in the monomer is polylnerized as a polymerization initiator.
Also, during suspension polymerization of the monomer in the medium in the presence of an oil-soluble polyinerization initiator (will be referred to as "initiator"
hereinunder), a monomer selected from hexafluoropropylene, ethylene tetrafluoride, etc. may be used as a copolyiner component in 3 to 7.5 % by weight of all the monomers to provide a copolyiner.
A chain transfer agent used at this tune includes acetone, isopropyl acetate, ethyl acetate, diethyl carbonate, di.methyl carbonate, baked ethyl carbonate, propionic acid, trifluoroacetic acid, trifluoroethyl alcohol, fonnaldehyde diinethyl acetal, 1, 3-butadiene epoxide, 1, 4-dioxane, (3-buthyl lactone, ethylene carbonate, vinylene carbonate or the like. A.inong them, however, acetone or ethylene acetate should preferably be used for the easy availability and handling.
The initiator may be any one of dinonnalpropyl peroxidicarbonate (NPP), diisopropyl peroxidicarbonate or the like. For each of the initiator and chain transfer agent, a kind and amount may be selected and one or more than two kinds be used in combination to attain a desired molecular weight.
The dispersant usable in the process of preparing the electrolyte may be any one of partially suspended polyvinyl acetate used in ordinary suspension polymerization, a water-soluble cellulose ether such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose or the like, a water-soluble polylner such as gelatin or the like, for exalnple.
The water, monomer, dispersant, initiator, chain transfer agent and other auxiliaries may be charged in any manner which would be suitably used in ordinary suspension polylnerization.
For example, the water, dispersant, initiator, chain transfer agent and other auxiliaries are charged, and then put under a reduced pressure for deaeration, the monomer is charged, and agitation of the lnixture is started. After the mixture reaches a predetermined temperature, it is kept at that temperature for proceeding of the polymerization. When the conversion reaches, for exalnple, 10 to 50 %, the chain transfer agent is charged under pressure. The polymerization is further allowed to progress. When the conversion reaches 80% or more, for exalnple, an unreacted monomer is recovered. Then the polymer is dehydrated, washed and dried to provide l~
a polymer.
At this tiune, by controlling the tuning of introducing vinylidene fluoride and hexafluoropropylene, that of introducing a chain transfer agent, polymerization teinperature profile, pressure and reaction time, etc., a block copolyinerized polyiner can be provided.
Siinilarly, by controlling the teinperature, pressure and reaction tiine appropriately at this time, it is possible to control the weight-average inolecular weight of a block copolymer thus propduced.
The block copolyiner thus produced fonns, together with the electrolyte salt and solvent (in addition, a plasticizer for a gel electrolyte), a solid or gel electrolyte. The electrolyte is provided between a positive electrode and negative electrode.
At this tune, the fluorocarbon polyiner should preferably be iunpregnated in the state of a solution into the active znaterial of the positive or negative electrode, and the solvent be removed for solidification of the electrolyte. Thereby a part of the electrolyte is unpregnated into the active material of the positive or negative electrode to provide a higher adhesive strength which can ensure an unproved adhesion of the electrolyte to the electrodes.
In the solid or gel electrolyte, the inatrix polymer is used in 2 to 20 % by weight and the balance is the solvent having an ester, or ether or a carbonate as one component of the solvent or plasticizer.
The solid or gel electrolyte contains a lithium salt which may be a one used in ordinary battery electrolytes. More particularly, the lithium salt may be a one selected from lithiuin chloride, lithiuln broinide, lithiuln iodide, lithiuin chlorate, lithium perchlorate, lithitun bromate, lithium iodate, lithium nitrate, tetrafluoro lithium borate, hexafluoro lithiuin phosphate, lithiuln acetate, bis(trifluoroinethane sulfonyl)iinide lithium, LiAsF6, LiCF3SO3, LiC(SO2CF3)3, LiA1Cl4, LiSiF6, etc.
These lithium salts may be used singly or in coinbination as lnixed together, but ainong them, LiPF6 and LiBF4 should desirably be used for the oxidation stability.
The dissolution concentration of the lithium salt should preferably be 0.1 to 3.0 mols /liter in the plasticizer for a gel electrode, and more preferably 0.5 to 2.0 mols/liter.
The solid-electrolyte secondary battery according to the present invention can be constructed similarly to the conventional lithium ion secondary battery provided that it uses the above-mentioned solid or gel electrolyte.
That is, the negative electrode of a lithium ion battery may be made of a material into or from which lithium ion can be inserted or extracted. The material for the negative electrode may be, for example, a carbon material such as a carbon material difficult to be graphitized or a graphite material. More particularly, the material may be any one selected from carbon materials such as pyrocarbons, cokes (pitch coke, needle coke, petroleum coke), graphites, vitreous carbons, sintered organic high molecular compounds (phenol resin, furan resin or the like sintered at an appropriate temperature for carbonization), carbon fiber, activated charcoal and the like. In addition, it may be any one of materials into or from which lithium ion can be inserted or extracted, including high molecular compounds such as polyacetylene, polypropyl, etc., oxides such as SnO2, etc. For fonning a negative electrode from such a material, a well-known binder or the like may be added to the material.
The positive electrode may be fonned from a metal oxide, metal sulfide or a special high molecular compound used as a positive electrode active material depending upon an intended type of battery. For a lithium ion battery, for example, the positive electrode active material may be a metal sulfide or oxide containing no lithium such as TiS,, MoS2, NbSe,, V`O5 or the like, or a lithium coinposite oxide or the like containing as the base LiMxO2 (M is one or more kind of transition metal, and x differs depending upon the charged or discharged extent of the battery, nonnally over 0.05 and under 1.10). The transition metal M coinposing the lithiuin composite oxide should preferably be Co, Ni, Mn or the like. More particularly, the lithiwn composite oxides include LiCoO2, LiNiO2, LiNi,, Co,i_,,02 (0 < y< 1), LiMn2O4.
These lithiuin composite oxides can be a positive electrode active material allowing to generate a high voltage and excellent in energy density. The positive electrode may be fonned from more than one of these active materials. For fonning a positive electrode from any of these active materials, a well-known conducting material, binder or the like may be added to the active material.
The battery according to the present invention is not limited to any special shape but may be designed to have a cylindrical, square or rectangular, coin, button or any other shape. Also, the battery according to the present invention may freely be dunensioned large, thin or otherwise.
The present invention will further be described herebelow concerning the experimental embodiments of the battery based on the experiment results.
Example of polymerizing conditions for fluorocarbon pol,ylner Following monomers and auxiliaries were charged into a pressure-resistant autoclave made of a stainless steel and having a volume of 14 liters, and the polymerization was started at a temperature of 25 C:
Vinylidene fluoride 93 parts by weight (3,000 g) Hexafluoropropylene 7 parts by weight Purified water 300 parts by weight Methyl cellulose 0.1 part by weight Soda pyrophosphate 0.2 part by weight NPP 0.61 part by weight In 3 to 24 hours after start of the polymerization (when the conversion of 30 to 80 % has been attained), 3.0 parts by weight of ethyl acetate was added to the lnixture and the polymerization was allowed to proceed. When the internal pressure of the polymerization container decreased by 50% for example from the equilibrium pressure after the polyinerization was started down, the unreacted monomer was recovered, a polymer sluny thus produced was dehydrated, washed and dried.
Confinnation of block copolymerization degree A differential scanning calorimeter (DSC: TAlOA by Metler) was used to heat a resin powder sainple at a rate of 10 C/inin from 30 C in a nitrogen atmosphere and determine a DSC curve. A temperature at which the heat absorption due to the melting of the resin crystal reached a peak was taken as the melting point of the resin.
In a vinylidene fluoride/hexafluoropropylene block copolyiner having a molecular weight equivalent to that of a polyvinylidene fluoride of which the melting point is 175 C as measured by the DSC, the random copolymer showed a combination of a crystallinity of the vinylidene fluoride and a flexibility of the hexafluoropropylene, and had a melting point of 130 to 140 C or so as in the case when the crystallinity is simply lowered. On the contrary, the block copolylner reflected the properties of the individual monomers. For example, the crystallilinity of the vinylidene fluoride was found not to impair the crystallinity of the block copolymer and the block copolylner showed a melting point of 150 C or so which is near a lniddle point between the melting points of the individual monomers, nalnely, vinylidene fluoride and hexafluoropropylene, respectively.
Therefore, the difference in melting point assures the block copolyinerization degree.
Molecular weight measurement a. Distribution of molecular weight (Mw/Mn) A gel-permeation chromatograph (8010 series by Toso, with two coluinns TSK-GEL GMHXL of 7.8 lnln in dialneter, 300 mm in length, connected in series) was used to measure the weight-average molecular weight (Mw) of a dimethyl acetoamide solution in which the powder of the polymer obtained as in the above was dissolved at a concentration of 0.2 % by weight at a temperature of 40 C and flow rate of 0.81n1/min.
b. Composition analysis of the polyrner The composition was measured using'9F NMR.
c. Logarithlnic viscosity nulnber A Ubbelohde viscometer was used to measure an efflux tune at 30 C of a solution in which the powder of the polylner was dissolved in dimethyl fonnamide at a concentration of 4 g/liter. The following equation was used to calculate a logarithinic viscosity nuinber from the measured efflux time:
Logarithlnic viscosity nuinber [rl] = 1n(rlrel)/C (dl/g) where r1rel: Efflux tiune of sainple solution/Efflux ti.lne of solvent C: Concentration of salnple solution (0.4 g/dl) FIG.1 shows the correlation between the measured weight-average molecular weight (Mw), nulnber-average molecular weight (Mn) and logarithlnic viscosity number.
Experimental embodiment 1 First, a negative electrode was prepared as in the following:
90 parts by weight of a crushed graphite powder and 10 parts by weight of vinylidene fluoride/hexafluoropropylene copolymer as a binder were mixed together to prepare a negative electrode lnixture. The inixture was dispersed in N-methyl-2-pyrolidone to produce a slurry.
The sluny was applied unifonnly to one side of a copper foil stripe of 10 in in thickness, used as an anode collector. After the slurry was dried, the copper foil stripe was compressed and fonned by a roll press to prepare a negative electrode.
On the other hand, a positive electrode was prepared as in the following:
To produce a positive electrode active material (LiCoO2), lithiuin carbonate and cobalt carbonate were mixed at a ratio of 0.5 mol to 1 mol and sintered in the atlnosphere at 900 C for 5 hours. Ninety one parts by weight of the LiCoO2 thus produced, 6 parts by weight of graphite as a conducting material and 10 parts by weight of vinylidene fluoride/hexafluoropropylene copolylner were lnixed together to prepare a positive electrode lnixture. The lnixture was further dispersed in N-methyl-2-pyrolidone to produce a slurry. The slurry was applied unifonnly to one side of an aluininuln foil stripe of 20 m in thickness used as an cathode collector.
After the sluny was dried, the alulninuln foil stripe was compressed and fonned by the roll press to produce a positive electrode.
Further, a solid electrolyte (or gel electrolyte) was prepared as in the following:
The negative and positive electrodes were applied unifonnly with a solution in which 30 parts by weight of a plasticizer composed of 42.5 parts by weight of ethylene carbonate (EC), 42.5 parts by weight of propylene carbonate (PC) and 15 parts by weight of LiPF6, 10 parts by weight of the vinylidene fluoride/hexafluoropropylene block copolymer (containing hexafluoropropylene in 7.0% by weight as measured by NMR) being a matrix polymer of 600,000 in weight-average molecular weight (logarithinic viscosity number of 1.93) and 60 parts by weight of diethyl carbonate were mixed and dissolved. Thus, the solution was impregnated into the electrodes.
The electrodes were left at nonnal temperature for 8 hours. Thereafter, the dilnethyl carbonate was vaporized for removal to provide a gel electrolyte. At this tilne, the thickness of the gel electrolyte was 25 ln at both the positive and negative electrodes ( the distance between the positive and negative electrodes joined to each other was taken as the thickness of the gel electrolyte layer).
The negative and positive electrodes applied with the gel electrolyte were superposed one on another for the gel electrolytes thereon to opposite to each other, and a pressure was applied to the electrodes, thereby preparing a flat gel-electrode battery of 2. 5 cm by 4.0 cm in area and 0.3 min in thickness.
FIG. 2 schematically illustrates the battery thus prepared. As seen, it comprises a negative electrode having an anode collector 1 on which an anode active lnaterial layer 2 was formed, a positive electrode having a cathode collector 3 on which a cathode active material layer 4 is fornzed, and a gel electrolyte 5 applied to the anode and cathode active lnaterial layers 2 and 4, respectively.
Experimental embodiment 2 A flat gel electrolyte battery was prepared in a similar.manner to that in the experimental embodiment 1 having been described above except that 7 parts by weight of a vinylidene fluoride/hexafluoropropylene block copolyiner of 700,000 in weight-average molecular weight (Mw) (content of the hexafluoropropylene was 7.0 % by weight as measured by NMR) and 3 parts by weight of a vinylidene fluoride/hexafluoropropylene block copolymer of 300,000 in weight-average molecular weight (Mw) (content of the hexafluoropropylene was 7.0 % by weight as measured by NMR) were used at a ratio of 7: 3 as matrix polyiners.
Comparative exainple 1 A flat gel electrolyte battery was prepared in a similar manner to that in the experimental embodiment 1 having been described above except that a vinylidene fluoride/hexafluoropropylene copolymer having a weight-average molecular weight (Mw) of 300,000 (content of the hexafluoropropylene was 7.0 % by weight as measured by NMR) was used as a matrix polylner.
Comparative exalnple 2 A flat gel electrolyte battery was prepared in a similar manner to that in the experilnental embodiment 1 having been described above except that a polyvinylidene fluoride/hexafluoropropylene copolymer having a weight-average molecular weight (Mw) of 600,000 (content of the hexafluoropropylene was 7.0 % by weight as measured by NMR) was used as a matrix polyiner.
Comparative example 3 A flat gel electrolyte battery was prepared in a similar manner to that in the experilnental embodiment 1 having been described above except that a vinylidene fluoride/hexafluoropropy]ene copolymer having a weight-average molecular weight (Mw) of 300,000 (ordinary random copolymer; content of the hexafluoropropylene was 7.0 % by weight as measured by NMR) was used as a matrix polymer.
Evaluation The experunental embodiinents 1 and 2 and comparative exainples 1 to 3 were tested on the peel strength, and further on the charge and discharge cycle life, shortr-circuit, load characteristic and low-temperature perfonnance.
The peel strength was ineasured as in the following. Nainely, an electrode active material layer 12 was fonned on an electric collector 11, and a gel electrolyte 13 was applied to the active material 12,, as shown in FIG. 3. The test piece thus prepared was pulled in the direction of arrow (180 ) with a weight of 500 g at a rate of 10 cin/sec or so. The test results are shown in Table 1 with a marking (0) for the breakage of the gel electrolyte 13 at the end of the electrode active material layer 12 and a marking (x) for the peeling of the gel electrolyte 13 and electrode active material layer 12 from the boundary between them, (0) representing breakage and partial peeling.
On the other hand, the charge and discharge cycle test was done 500 cycles by discharging the theoretical capacity (0.5C) for 2 hours (hourly rate). Each of the batteries was evaluated as in the following.
Each battery was charged at a constant current and voltage at a temperature of 23 C up to the upper liunit of 4.2 V, and then discharged at a constant current (0.5C) down to an end voltage of 3.2 V. The discharge capacity was thus detennined and evaluated with a discharge output maintenance factor after the 500 cycles of charge and discharge.
For the short-circuit test, 100 test batteries were prepared and they were charged and discharged for 500 cycles. Then the survival rate was measured.
The load characteristic was detennined by charging each of the batteries at a constant current and voltage up to an upper lilnit of 4.2 V at 23 C, discharging the battery for a 1 hourly rate (1C), for a 1/2 hourly rate (2C) and for a 1/3 hourly rate (3C) at the constant current and voltage at an end voltage of 3.2 V. The discharging capacity was thus detennined. A mean voltage was calculated from the discharging capacities. The output at each hourly rate was calculated in percentage with reference to 1/5C.
The low-temperature perfonnance was evaluated at temperatures of 0 C, -10 C and -20 C. At each of these temperatures, each battery was charged at a constant current and voltage at 23 C up to 4.2 V, and discharged at a 2 hourly rate (1/2C) of the theoretical capacity at the constant current and voltage down to the end voltage of 3.2 V. A mean voltage was detennined from the measurements, and further the output at the 2 hourly rate (1/2C) at each temperature was calculated in percentage with reference to a discharge at nonnal temperature.
The test results are also shown in Table 1.
Table 1 Peel Discltarge output Short- Load characteristic Low-temperature strenCth maintenance factor circuit performance (0.5C) after 500 1C 2C 3C 0 10 C 20 C
cycles C
Embodiment 1 0 92% 100/100 98 97 95 90 75 40 Embodiment 2 0 93% 100/100 99 98 96 92 78 45 Comparative A 80% 60/100 98 90 70 85 30 10 example 1 Comparative A 60% 20/100 97 90 50 85 30 15 example 2 Comparative x 40% 0/100 80 60 30 85 30 10 example 3 As apparent froln Table 1, each of the experiunental embodiments in which the block copol}nner was used as a matrix polymer of a gel electrolyte was proved to have an excellent peel strength and output maintenance rate, no short-circuit, superior load characteristic and low-temperature perfonnance.
As having been described in the foregoing, the present invention can provide a solid electrolyte excellent in adhesion to the electrode active material layers, and thus the present invention can also provide a solid-electrolyte secondary battery with a solid electrolyte having a good electrical contact with positive and negative active material layers and having a considerably improved charge and discharge cycle life.
Since the solid electrolyte in the solid-electrolyte secondary battery according to the present invention has a high mechanical toughness and a excellent solvent retaining capability, the battery is excellent in load characteristic and low-temperature perfonnance.
Therefore, the esters, ethers or carbonates usable in the battery are limited of thelnselves.
The esters, ethers or carbonates included in the lunited range and having a weight-average molecular weight of more than 1,000,000 do not show a sufficient solubility to prepare a suitable solution.
Therefore, the weight-average molecular weight (Mw) of the block copolylner should preferably range from 550,000 to 3,000,000, and more preferably from 550,000 to 1,000,000.
In case a block copolylner of 550,000 or more in weight-average molecular weight (Mw) is used, another fluorocarbon of over 300,000 and under 550,000 in Mw may be used in combination to lower the viscosity for facilitating to fonn a film of the electrolyte. In this case, however, the ratio of the block copolylner of 550,000 or more in Mw should preferably be 30 % or more by weight. If the ratio of the block copolymer of 550,000 or more in Mw is lower, it will be difficult to ensure an intended sufficient adhesive strength of the solid electrolyte.
The block copolyiner of 550,000 or more in Mw is prepared by using a peroxide and polymerizing a monomer at a temperature ranging from room temperature to 200 C and under an atsnospheric pressure of 300 or less. It is industrially produced by the suspension polymerization or emulsion polyinerization process.
In the suspension polyznerization process, water is used as a medium, a dispersant is added to the monomer to disperse the latter as liquid drops into the medium, the organic peroxide dissolved in the monomer is polylnerized as a polymerization initiator.
Also, during suspension polymerization of the monomer in the medium in the presence of an oil-soluble polyinerization initiator (will be referred to as "initiator"
hereinunder), a monomer selected from hexafluoropropylene, ethylene tetrafluoride, etc. may be used as a copolyiner component in 3 to 7.5 % by weight of all the monomers to provide a copolyiner.
A chain transfer agent used at this tune includes acetone, isopropyl acetate, ethyl acetate, diethyl carbonate, di.methyl carbonate, baked ethyl carbonate, propionic acid, trifluoroacetic acid, trifluoroethyl alcohol, fonnaldehyde diinethyl acetal, 1, 3-butadiene epoxide, 1, 4-dioxane, (3-buthyl lactone, ethylene carbonate, vinylene carbonate or the like. A.inong them, however, acetone or ethylene acetate should preferably be used for the easy availability and handling.
The initiator may be any one of dinonnalpropyl peroxidicarbonate (NPP), diisopropyl peroxidicarbonate or the like. For each of the initiator and chain transfer agent, a kind and amount may be selected and one or more than two kinds be used in combination to attain a desired molecular weight.
The dispersant usable in the process of preparing the electrolyte may be any one of partially suspended polyvinyl acetate used in ordinary suspension polymerization, a water-soluble cellulose ether such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose or the like, a water-soluble polylner such as gelatin or the like, for exalnple.
The water, monomer, dispersant, initiator, chain transfer agent and other auxiliaries may be charged in any manner which would be suitably used in ordinary suspension polylnerization.
For example, the water, dispersant, initiator, chain transfer agent and other auxiliaries are charged, and then put under a reduced pressure for deaeration, the monomer is charged, and agitation of the lnixture is started. After the mixture reaches a predetermined temperature, it is kept at that temperature for proceeding of the polymerization. When the conversion reaches, for exalnple, 10 to 50 %, the chain transfer agent is charged under pressure. The polymerization is further allowed to progress. When the conversion reaches 80% or more, for exalnple, an unreacted monomer is recovered. Then the polymer is dehydrated, washed and dried to provide l~
a polymer.
At this tiune, by controlling the tuning of introducing vinylidene fluoride and hexafluoropropylene, that of introducing a chain transfer agent, polymerization teinperature profile, pressure and reaction time, etc., a block copolyinerized polyiner can be provided.
Siinilarly, by controlling the teinperature, pressure and reaction tiine appropriately at this time, it is possible to control the weight-average inolecular weight of a block copolymer thus propduced.
The block copolyiner thus produced fonns, together with the electrolyte salt and solvent (in addition, a plasticizer for a gel electrolyte), a solid or gel electrolyte. The electrolyte is provided between a positive electrode and negative electrode.
At this tune, the fluorocarbon polyiner should preferably be iunpregnated in the state of a solution into the active znaterial of the positive or negative electrode, and the solvent be removed for solidification of the electrolyte. Thereby a part of the electrolyte is unpregnated into the active material of the positive or negative electrode to provide a higher adhesive strength which can ensure an unproved adhesion of the electrolyte to the electrodes.
In the solid or gel electrolyte, the inatrix polymer is used in 2 to 20 % by weight and the balance is the solvent having an ester, or ether or a carbonate as one component of the solvent or plasticizer.
The solid or gel electrolyte contains a lithium salt which may be a one used in ordinary battery electrolytes. More particularly, the lithium salt may be a one selected from lithiuin chloride, lithiuln broinide, lithiuln iodide, lithiuin chlorate, lithium perchlorate, lithitun bromate, lithium iodate, lithium nitrate, tetrafluoro lithium borate, hexafluoro lithiuin phosphate, lithiuln acetate, bis(trifluoroinethane sulfonyl)iinide lithium, LiAsF6, LiCF3SO3, LiC(SO2CF3)3, LiA1Cl4, LiSiF6, etc.
These lithium salts may be used singly or in coinbination as lnixed together, but ainong them, LiPF6 and LiBF4 should desirably be used for the oxidation stability.
The dissolution concentration of the lithium salt should preferably be 0.1 to 3.0 mols /liter in the plasticizer for a gel electrode, and more preferably 0.5 to 2.0 mols/liter.
The solid-electrolyte secondary battery according to the present invention can be constructed similarly to the conventional lithium ion secondary battery provided that it uses the above-mentioned solid or gel electrolyte.
That is, the negative electrode of a lithium ion battery may be made of a material into or from which lithium ion can be inserted or extracted. The material for the negative electrode may be, for example, a carbon material such as a carbon material difficult to be graphitized or a graphite material. More particularly, the material may be any one selected from carbon materials such as pyrocarbons, cokes (pitch coke, needle coke, petroleum coke), graphites, vitreous carbons, sintered organic high molecular compounds (phenol resin, furan resin or the like sintered at an appropriate temperature for carbonization), carbon fiber, activated charcoal and the like. In addition, it may be any one of materials into or from which lithium ion can be inserted or extracted, including high molecular compounds such as polyacetylene, polypropyl, etc., oxides such as SnO2, etc. For fonning a negative electrode from such a material, a well-known binder or the like may be added to the material.
The positive electrode may be fonned from a metal oxide, metal sulfide or a special high molecular compound used as a positive electrode active material depending upon an intended type of battery. For a lithium ion battery, for example, the positive electrode active material may be a metal sulfide or oxide containing no lithium such as TiS,, MoS2, NbSe,, V`O5 or the like, or a lithium coinposite oxide or the like containing as the base LiMxO2 (M is one or more kind of transition metal, and x differs depending upon the charged or discharged extent of the battery, nonnally over 0.05 and under 1.10). The transition metal M coinposing the lithiuin composite oxide should preferably be Co, Ni, Mn or the like. More particularly, the lithiwn composite oxides include LiCoO2, LiNiO2, LiNi,, Co,i_,,02 (0 < y< 1), LiMn2O4.
These lithiuin composite oxides can be a positive electrode active material allowing to generate a high voltage and excellent in energy density. The positive electrode may be fonned from more than one of these active materials. For fonning a positive electrode from any of these active materials, a well-known conducting material, binder or the like may be added to the active material.
The battery according to the present invention is not limited to any special shape but may be designed to have a cylindrical, square or rectangular, coin, button or any other shape. Also, the battery according to the present invention may freely be dunensioned large, thin or otherwise.
The present invention will further be described herebelow concerning the experimental embodiments of the battery based on the experiment results.
Example of polymerizing conditions for fluorocarbon pol,ylner Following monomers and auxiliaries were charged into a pressure-resistant autoclave made of a stainless steel and having a volume of 14 liters, and the polymerization was started at a temperature of 25 C:
Vinylidene fluoride 93 parts by weight (3,000 g) Hexafluoropropylene 7 parts by weight Purified water 300 parts by weight Methyl cellulose 0.1 part by weight Soda pyrophosphate 0.2 part by weight NPP 0.61 part by weight In 3 to 24 hours after start of the polymerization (when the conversion of 30 to 80 % has been attained), 3.0 parts by weight of ethyl acetate was added to the lnixture and the polymerization was allowed to proceed. When the internal pressure of the polymerization container decreased by 50% for example from the equilibrium pressure after the polyinerization was started down, the unreacted monomer was recovered, a polymer sluny thus produced was dehydrated, washed and dried.
Confinnation of block copolymerization degree A differential scanning calorimeter (DSC: TAlOA by Metler) was used to heat a resin powder sainple at a rate of 10 C/inin from 30 C in a nitrogen atmosphere and determine a DSC curve. A temperature at which the heat absorption due to the melting of the resin crystal reached a peak was taken as the melting point of the resin.
In a vinylidene fluoride/hexafluoropropylene block copolyiner having a molecular weight equivalent to that of a polyvinylidene fluoride of which the melting point is 175 C as measured by the DSC, the random copolymer showed a combination of a crystallinity of the vinylidene fluoride and a flexibility of the hexafluoropropylene, and had a melting point of 130 to 140 C or so as in the case when the crystallinity is simply lowered. On the contrary, the block copolylner reflected the properties of the individual monomers. For example, the crystallilinity of the vinylidene fluoride was found not to impair the crystallinity of the block copolymer and the block copolylner showed a melting point of 150 C or so which is near a lniddle point between the melting points of the individual monomers, nalnely, vinylidene fluoride and hexafluoropropylene, respectively.
Therefore, the difference in melting point assures the block copolyinerization degree.
Molecular weight measurement a. Distribution of molecular weight (Mw/Mn) A gel-permeation chromatograph (8010 series by Toso, with two coluinns TSK-GEL GMHXL of 7.8 lnln in dialneter, 300 mm in length, connected in series) was used to measure the weight-average molecular weight (Mw) of a dimethyl acetoamide solution in which the powder of the polymer obtained as in the above was dissolved at a concentration of 0.2 % by weight at a temperature of 40 C and flow rate of 0.81n1/min.
b. Composition analysis of the polyrner The composition was measured using'9F NMR.
c. Logarithlnic viscosity nulnber A Ubbelohde viscometer was used to measure an efflux tune at 30 C of a solution in which the powder of the polylner was dissolved in dimethyl fonnamide at a concentration of 4 g/liter. The following equation was used to calculate a logarithinic viscosity nuinber from the measured efflux time:
Logarithlnic viscosity nuinber [rl] = 1n(rlrel)/C (dl/g) where r1rel: Efflux tiune of sainple solution/Efflux ti.lne of solvent C: Concentration of salnple solution (0.4 g/dl) FIG.1 shows the correlation between the measured weight-average molecular weight (Mw), nulnber-average molecular weight (Mn) and logarithlnic viscosity number.
Experimental embodiment 1 First, a negative electrode was prepared as in the following:
90 parts by weight of a crushed graphite powder and 10 parts by weight of vinylidene fluoride/hexafluoropropylene copolymer as a binder were mixed together to prepare a negative electrode lnixture. The inixture was dispersed in N-methyl-2-pyrolidone to produce a slurry.
The sluny was applied unifonnly to one side of a copper foil stripe of 10 in in thickness, used as an anode collector. After the slurry was dried, the copper foil stripe was compressed and fonned by a roll press to prepare a negative electrode.
On the other hand, a positive electrode was prepared as in the following:
To produce a positive electrode active material (LiCoO2), lithiuin carbonate and cobalt carbonate were mixed at a ratio of 0.5 mol to 1 mol and sintered in the atlnosphere at 900 C for 5 hours. Ninety one parts by weight of the LiCoO2 thus produced, 6 parts by weight of graphite as a conducting material and 10 parts by weight of vinylidene fluoride/hexafluoropropylene copolylner were lnixed together to prepare a positive electrode lnixture. The lnixture was further dispersed in N-methyl-2-pyrolidone to produce a slurry. The slurry was applied unifonnly to one side of an aluininuln foil stripe of 20 m in thickness used as an cathode collector.
After the sluny was dried, the alulninuln foil stripe was compressed and fonned by the roll press to produce a positive electrode.
Further, a solid electrolyte (or gel electrolyte) was prepared as in the following:
The negative and positive electrodes were applied unifonnly with a solution in which 30 parts by weight of a plasticizer composed of 42.5 parts by weight of ethylene carbonate (EC), 42.5 parts by weight of propylene carbonate (PC) and 15 parts by weight of LiPF6, 10 parts by weight of the vinylidene fluoride/hexafluoropropylene block copolymer (containing hexafluoropropylene in 7.0% by weight as measured by NMR) being a matrix polymer of 600,000 in weight-average molecular weight (logarithinic viscosity number of 1.93) and 60 parts by weight of diethyl carbonate were mixed and dissolved. Thus, the solution was impregnated into the electrodes.
The electrodes were left at nonnal temperature for 8 hours. Thereafter, the dilnethyl carbonate was vaporized for removal to provide a gel electrolyte. At this tilne, the thickness of the gel electrolyte was 25 ln at both the positive and negative electrodes ( the distance between the positive and negative electrodes joined to each other was taken as the thickness of the gel electrolyte layer).
The negative and positive electrodes applied with the gel electrolyte were superposed one on another for the gel electrolytes thereon to opposite to each other, and a pressure was applied to the electrodes, thereby preparing a flat gel-electrode battery of 2. 5 cm by 4.0 cm in area and 0.3 min in thickness.
FIG. 2 schematically illustrates the battery thus prepared. As seen, it comprises a negative electrode having an anode collector 1 on which an anode active lnaterial layer 2 was formed, a positive electrode having a cathode collector 3 on which a cathode active material layer 4 is fornzed, and a gel electrolyte 5 applied to the anode and cathode active lnaterial layers 2 and 4, respectively.
Experimental embodiment 2 A flat gel electrolyte battery was prepared in a similar.manner to that in the experimental embodiment 1 having been described above except that 7 parts by weight of a vinylidene fluoride/hexafluoropropylene block copolyiner of 700,000 in weight-average molecular weight (Mw) (content of the hexafluoropropylene was 7.0 % by weight as measured by NMR) and 3 parts by weight of a vinylidene fluoride/hexafluoropropylene block copolymer of 300,000 in weight-average molecular weight (Mw) (content of the hexafluoropropylene was 7.0 % by weight as measured by NMR) were used at a ratio of 7: 3 as matrix polyiners.
Comparative exainple 1 A flat gel electrolyte battery was prepared in a similar manner to that in the experimental embodiment 1 having been described above except that a vinylidene fluoride/hexafluoropropylene copolymer having a weight-average molecular weight (Mw) of 300,000 (content of the hexafluoropropylene was 7.0 % by weight as measured by NMR) was used as a matrix polylner.
Comparative exalnple 2 A flat gel electrolyte battery was prepared in a similar manner to that in the experilnental embodiment 1 having been described above except that a polyvinylidene fluoride/hexafluoropropylene copolymer having a weight-average molecular weight (Mw) of 600,000 (content of the hexafluoropropylene was 7.0 % by weight as measured by NMR) was used as a matrix polyiner.
Comparative example 3 A flat gel electrolyte battery was prepared in a similar manner to that in the experilnental embodiment 1 having been described above except that a vinylidene fluoride/hexafluoropropy]ene copolymer having a weight-average molecular weight (Mw) of 300,000 (ordinary random copolymer; content of the hexafluoropropylene was 7.0 % by weight as measured by NMR) was used as a matrix polymer.
Evaluation The experunental embodiinents 1 and 2 and comparative exainples 1 to 3 were tested on the peel strength, and further on the charge and discharge cycle life, shortr-circuit, load characteristic and low-temperature perfonnance.
The peel strength was ineasured as in the following. Nainely, an electrode active material layer 12 was fonned on an electric collector 11, and a gel electrolyte 13 was applied to the active material 12,, as shown in FIG. 3. The test piece thus prepared was pulled in the direction of arrow (180 ) with a weight of 500 g at a rate of 10 cin/sec or so. The test results are shown in Table 1 with a marking (0) for the breakage of the gel electrolyte 13 at the end of the electrode active material layer 12 and a marking (x) for the peeling of the gel electrolyte 13 and electrode active material layer 12 from the boundary between them, (0) representing breakage and partial peeling.
On the other hand, the charge and discharge cycle test was done 500 cycles by discharging the theoretical capacity (0.5C) for 2 hours (hourly rate). Each of the batteries was evaluated as in the following.
Each battery was charged at a constant current and voltage at a temperature of 23 C up to the upper liunit of 4.2 V, and then discharged at a constant current (0.5C) down to an end voltage of 3.2 V. The discharge capacity was thus detennined and evaluated with a discharge output maintenance factor after the 500 cycles of charge and discharge.
For the short-circuit test, 100 test batteries were prepared and they were charged and discharged for 500 cycles. Then the survival rate was measured.
The load characteristic was detennined by charging each of the batteries at a constant current and voltage up to an upper lilnit of 4.2 V at 23 C, discharging the battery for a 1 hourly rate (1C), for a 1/2 hourly rate (2C) and for a 1/3 hourly rate (3C) at the constant current and voltage at an end voltage of 3.2 V. The discharging capacity was thus detennined. A mean voltage was calculated from the discharging capacities. The output at each hourly rate was calculated in percentage with reference to 1/5C.
The low-temperature perfonnance was evaluated at temperatures of 0 C, -10 C and -20 C. At each of these temperatures, each battery was charged at a constant current and voltage at 23 C up to 4.2 V, and discharged at a 2 hourly rate (1/2C) of the theoretical capacity at the constant current and voltage down to the end voltage of 3.2 V. A mean voltage was detennined from the measurements, and further the output at the 2 hourly rate (1/2C) at each temperature was calculated in percentage with reference to a discharge at nonnal temperature.
The test results are also shown in Table 1.
Table 1 Peel Discltarge output Short- Load characteristic Low-temperature strenCth maintenance factor circuit performance (0.5C) after 500 1C 2C 3C 0 10 C 20 C
cycles C
Embodiment 1 0 92% 100/100 98 97 95 90 75 40 Embodiment 2 0 93% 100/100 99 98 96 92 78 45 Comparative A 80% 60/100 98 90 70 85 30 10 example 1 Comparative A 60% 20/100 97 90 50 85 30 15 example 2 Comparative x 40% 0/100 80 60 30 85 30 10 example 3 As apparent froln Table 1, each of the experiunental embodiments in which the block copol}nner was used as a matrix polymer of a gel electrolyte was proved to have an excellent peel strength and output maintenance rate, no short-circuit, superior load characteristic and low-temperature perfonnance.
As having been described in the foregoing, the present invention can provide a solid electrolyte excellent in adhesion to the electrode active material layers, and thus the present invention can also provide a solid-electrolyte secondary battery with a solid electrolyte having a good electrical contact with positive and negative active material layers and having a considerably improved charge and discharge cycle life.
Since the solid electrolyte in the solid-electrolyte secondary battery according to the present invention has a high mechanical toughness and a excellent solvent retaining capability, the battery is excellent in load characteristic and low-temperature perfonnance.
Claims (11)
1. A solid-electrolyte secondary battery comprising:
(a) a positive electrode;
(b) a negative electrode;
(c) a solid electrolyte disposed between the positive and negative electrodes, the solid electrolyte comprising a vinylidene fluoride/hexafluoropropylene block copolymer as a matrix polymer, the electrolyte containing lithium salt, the salt having a dissolution concentration of 0.1 to 3.0 mols/ltr;
(d) wherein the positive electrode comprises a first face and the negative electrode comprises a second face, the first face being spaced apart from the second face with the solid electrolyte sandwiched therebetween, the solid electrolyte further formed on the first face, or the second face, or on both, a solid electrolyte layer being obtained by impregnating a solution containing a solvent in which the solid electrolyte is dissolved into the first face, or the second face, or both, and removing the solvent from the solution;
(e) wherein the vinylidene fluoride/hexafluoropropylene block copolymer comprises a first component having a weight-average molecular weight of greater than 550,000, a second component having a weight-average molecular weight of greater than 300,000 and less than 550,000;
(f) wherein the vinylidene fluoride/hexafluoropropylene block copolymer comprises from 3% to 7.5% by weight hexafluoropropylene; and (g) wherein the content of the first component with the weight-average molecular weight of greater than 550,000 is greater than 30% by weight in the matrix polymer.
(a) a positive electrode;
(b) a negative electrode;
(c) a solid electrolyte disposed between the positive and negative electrodes, the solid electrolyte comprising a vinylidene fluoride/hexafluoropropylene block copolymer as a matrix polymer, the electrolyte containing lithium salt, the salt having a dissolution concentration of 0.1 to 3.0 mols/ltr;
(d) wherein the positive electrode comprises a first face and the negative electrode comprises a second face, the first face being spaced apart from the second face with the solid electrolyte sandwiched therebetween, the solid electrolyte further formed on the first face, or the second face, or on both, a solid electrolyte layer being obtained by impregnating a solution containing a solvent in which the solid electrolyte is dissolved into the first face, or the second face, or both, and removing the solvent from the solution;
(e) wherein the vinylidene fluoride/hexafluoropropylene block copolymer comprises a first component having a weight-average molecular weight of greater than 550,000, a second component having a weight-average molecular weight of greater than 300,000 and less than 550,000;
(f) wherein the vinylidene fluoride/hexafluoropropylene block copolymer comprises from 3% to 7.5% by weight hexafluoropropylene; and (g) wherein the content of the first component with the weight-average molecular weight of greater than 550,000 is greater than 30% by weight in the matrix polymer.
2. The solid-electrolyte secondary battery of claim 1, wherein the solid electrolyte further comprises an electrolytic solution, the electrolytic solution being 80% by weight or more in proportion thereof.
3. The solid-electrolyte secondary battery of claim 1, wherein the negative electrode comprises a material into which a lithium ion can be inserted or from which a lithium ion can be extracted.
4. The solid-electrolyte secondary battery of claim 3, wherein said material comprises a carbon material.
5. The solid-electrolyte secondary battery of claim 1, wherein the positive electrode comprises a composite oxide of lithium and a transition metal.
6. A solid-electrolyte secondary battery, comprising:
(a) a positive electrode;
(b) a negative electrode;
(c) a solid electrolyte disposed between the positive and negative electrodes, the solid electrolyte comprising a vinylidene fluoride/hexafluoropropylene block copolymer as a matrix polymer, the electrolyte containing lithium salt, the salt having a dissolution concentration of 0.1 to 3.0 mols/ltr;
(d) wherein the positive electrode comprises a first face and the negative electrode comprises a second face, the first face being spaced apart from the second face with the solid electrolyte sandwiched therebetween, the solid electrolyte further formed on the first face, or the second face, or on both, the solid electrolyte being obtained by impregnating a solution containing a solvent in which the solid electrolyte is dissolved into the first face, or the second face, or both, and removing the solvent from the solution;
and (e) wherein the vinylidene fluoride/hexafluoropropylene block copolymer comprises a first component having a weight-average molecular weight of greater than 550,000, a second component having a weight-average molecular weight of greater than 300,000 and less than 550,000;
(f) wherein the vinylidene fluoride/hexafluoropropylene block copolymer comprises from 3% to 7.5% by weight hexafluoropropylene;
(g) wherein the solid electrolyte further comprises an electrolytic solution, the electrolytic solution being 80% by weight or more in proportion thereof;
(h) wherein the negative electrode comprises a material into which a lithium ion can be inserted or from which a lithium ion can be extracted; and (i) wherein the positive electrode comprises a composite oxide of lithium and a transition metal.
(a) a positive electrode;
(b) a negative electrode;
(c) a solid electrolyte disposed between the positive and negative electrodes, the solid electrolyte comprising a vinylidene fluoride/hexafluoropropylene block copolymer as a matrix polymer, the electrolyte containing lithium salt, the salt having a dissolution concentration of 0.1 to 3.0 mols/ltr;
(d) wherein the positive electrode comprises a first face and the negative electrode comprises a second face, the first face being spaced apart from the second face with the solid electrolyte sandwiched therebetween, the solid electrolyte further formed on the first face, or the second face, or on both, the solid electrolyte being obtained by impregnating a solution containing a solvent in which the solid electrolyte is dissolved into the first face, or the second face, or both, and removing the solvent from the solution;
and (e) wherein the vinylidene fluoride/hexafluoropropylene block copolymer comprises a first component having a weight-average molecular weight of greater than 550,000, a second component having a weight-average molecular weight of greater than 300,000 and less than 550,000;
(f) wherein the vinylidene fluoride/hexafluoropropylene block copolymer comprises from 3% to 7.5% by weight hexafluoropropylene;
(g) wherein the solid electrolyte further comprises an electrolytic solution, the electrolytic solution being 80% by weight or more in proportion thereof;
(h) wherein the negative electrode comprises a material into which a lithium ion can be inserted or from which a lithium ion can be extracted; and (i) wherein the positive electrode comprises a composite oxide of lithium and a transition metal.
7. A solid-electrolyte secondary battery, comprising:
(a) a positive electrode;
(b) a negative electrode;
(c) a solid electrolyte disposed between the positive and negative electrodes, the solid electrolyte comprising a vinylidene fluoride/hexafluoropropylene block copolymer as a matrix polymer, the electrolyte containing lithium salt, the salt having a dissolution concentration of 0.1 to 3.0 mols/ltr;
(d) wherein the positive electrode comprises a first face and the negative electrode comprises a second face, the first face being spaced apart from the second face with the solid electrolyte sandwiched therebetween, the solid electrolyte further formed on the first face, or the second face, or on both, a solid electrolyte layer being obtained by impregnating a solution containing a solvent in which the solid electrolyte is dissolved into the first face, or the second face, or both, and removing the solvent from the solution;
and (e) wherein the vinylidene fluoride/hexafluoropropylene block copolymer comprises a first component having a weight-average molecular weight of greater than 550,000, a second component having a weight-average molecular weight of greater than 300,000 and less than 550,000; and (f) wherein the vinylidene fluoride/hexafluoropropylene block copolymer comprises from 3% to 7.5% by weight hexafluoropropylene.
(a) a positive electrode;
(b) a negative electrode;
(c) a solid electrolyte disposed between the positive and negative electrodes, the solid electrolyte comprising a vinylidene fluoride/hexafluoropropylene block copolymer as a matrix polymer, the electrolyte containing lithium salt, the salt having a dissolution concentration of 0.1 to 3.0 mols/ltr;
(d) wherein the positive electrode comprises a first face and the negative electrode comprises a second face, the first face being spaced apart from the second face with the solid electrolyte sandwiched therebetween, the solid electrolyte further formed on the first face, or the second face, or on both, a solid electrolyte layer being obtained by impregnating a solution containing a solvent in which the solid electrolyte is dissolved into the first face, or the second face, or both, and removing the solvent from the solution;
and (e) wherein the vinylidene fluoride/hexafluoropropylene block copolymer comprises a first component having a weight-average molecular weight of greater than 550,000, a second component having a weight-average molecular weight of greater than 300,000 and less than 550,000; and (f) wherein the vinylidene fluoride/hexafluoropropylene block copolymer comprises from 3% to 7.5% by weight hexafluoropropylene.
8. The secondary battery of claim 7, wherein;
the solid electrolyte further comprises an electrolytic solution, the electrolytic solution being 80% by weight or more in proportion thereof.
the solid electrolyte further comprises an electrolytic solution, the electrolytic solution being 80% by weight or more in proportion thereof.
9. The secondary battery of claim 7, wherein;
the negative electrode comprises a material into which a lithium ion can be inserted or from which a lithium ion can be extracted.
the negative electrode comprises a material into which a lithium ion can be inserted or from which a lithium ion can be extracted.
10. The secondary battery of claim 7, wherein the positive electrode comprises a composite oxide of lithium and a transition metal.
11. The secondary battery of claim 7, wherein the solid electrolyte further comprises an electrolytic solution, the electrolytic solution being 80% by weight or more in proportion thereof; and the negative electrode comprises a material into which a lithium ion can be inserted or from which a lithium ion can be extracted.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11755198A JP4092669B2 (en) | 1998-04-27 | 1998-04-27 | Solid electrolyte secondary battery |
| JP10/117551 | 1998-04-27 | ||
| PCT/JP1999/002156 WO1999056337A1 (en) | 1998-04-27 | 1999-04-22 | Solid electrolytic secondary battery |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2294292A1 CA2294292A1 (en) | 1999-11-04 |
| CA2294292C true CA2294292C (en) | 2010-01-12 |
Family
ID=14714619
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002294292A Expired - Lifetime CA2294292C (en) | 1998-04-27 | 1999-04-22 | Solid electrolyte secondary battery |
Country Status (17)
| Country | Link |
|---|---|
| US (1) | US6506523B1 (en) |
| EP (1) | EP1001477B1 (en) |
| JP (1) | JP4092669B2 (en) |
| KR (1) | KR100613799B1 (en) |
| CN (1) | CN1149700C (en) |
| AT (1) | ATE452434T1 (en) |
| BR (1) | BR9906385A (en) |
| CA (1) | CA2294292C (en) |
| DE (1) | DE69941806D1 (en) |
| DK (1) | DK1001477T3 (en) |
| ES (1) | ES2338390T3 (en) |
| ID (2) | ID23699A (en) |
| MX (1) | MXPA99011835A (en) |
| MY (1) | MY122229A (en) |
| PT (1) | PT1001477E (en) |
| TW (1) | TW419850B (en) |
| WO (1) | WO1999056337A1 (en) |
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| JP4670246B2 (en) * | 2004-03-24 | 2011-04-13 | ソニー株式会社 | Lithium ion secondary battery |
| RU2295178C2 (en) * | 2005-04-21 | 2007-03-10 | Общество с ограниченной ответственностью "Высокоэнергетические батарейные системы" (ООО "ВЭБС") | Solid-state secondary power supply |
| US7776478B2 (en) * | 2005-07-15 | 2010-08-17 | Cymbet Corporation | Thin-film batteries with polymer and LiPON electrolyte layers and method |
| JP4363436B2 (en) | 2006-10-13 | 2009-11-11 | ソニー株式会社 | Secondary battery |
| JP5157362B2 (en) * | 2007-10-17 | 2013-03-06 | ソニー株式会社 | Non-aqueous electrolyte battery |
| WO2009092058A1 (en) * | 2008-01-16 | 2009-07-23 | Seeo, Inc | Gel polymer electrolytes for batteries |
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| JP2011065982A (en) * | 2009-08-18 | 2011-03-31 | Seiko Epson Corp | Lithium battery electrode body and lithium battery |
| CN109265739B (en) * | 2011-06-23 | 2021-02-02 | 索尔维特殊聚合物意大利有限公司 | Method for producing a battery component |
| JP6097284B2 (en) * | 2011-06-23 | 2017-03-15 | ソルベイ スペシャルティ ポリマーズ イタリー エス．ピー．エー． | Secondary battery |
| JP6398170B2 (en) * | 2013-10-11 | 2018-10-03 | 株式会社村田製作所 | Lithium ion secondary battery, battery pack, electric vehicle, power storage system, electric tool and electronic device |
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| JP6059743B2 (en) * | 2014-02-17 | 2017-01-11 | 富士フイルム株式会社 | Solid electrolyte composition, battery electrode sheet and all-solid secondary battery using the same, and method for producing the same |
| WO2015181666A1 (en) * | 2014-05-29 | 2015-12-03 | Semiconductor Energy Laboratory Co., Ltd. | Secondary battery and electronic device |
| CN105374980B (en) * | 2014-08-15 | 2021-07-13 | 北京卫蓝新能源科技有限公司 | Quasi-solid-state alkali metal battery with interface infiltration, battery electrode and battery preparation method |
| JP6829943B2 (en) * | 2016-03-10 | 2021-02-17 | 株式会社クレハ | Gel electrolyte and its preparation method |
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- 1998-04-27 JP JP11755198A patent/JP4092669B2/en not_active Expired - Lifetime
-
1999
- 1999-04-19 TW TW088106241A patent/TW419850B/en not_active IP Right Cessation
- 1999-04-22 US US09/446,291 patent/US6506523B1/en not_active Expired - Lifetime
- 1999-04-22 DE DE69941806T patent/DE69941806D1/en not_active Expired - Lifetime
- 1999-04-22 AT AT99917115T patent/ATE452434T1/en active
- 1999-04-22 WO PCT/JP1999/002156 patent/WO1999056337A1/en not_active Ceased
- 1999-04-22 BR BR9906385-9A patent/BR9906385A/en not_active Application Discontinuation
- 1999-04-22 CA CA002294292A patent/CA2294292C/en not_active Expired - Lifetime
- 1999-04-22 KR KR1019997012230A patent/KR100613799B1/en not_active Expired - Lifetime
- 1999-04-22 ES ES99917115T patent/ES2338390T3/en not_active Expired - Lifetime
- 1999-04-22 DK DK99917115.0T patent/DK1001477T3/en active
- 1999-04-22 ID IDW991589A patent/ID23699A/en unknown
- 1999-04-22 CN CNB99800636XA patent/CN1149700C/en not_active Expired - Lifetime
- 1999-04-22 PT PT99917115T patent/PT1001477E/en unknown
- 1999-04-22 MY MYPI99001574A patent/MY122229A/en unknown
- 1999-04-22 ID IDW991618A patent/ID24713A/en unknown
- 1999-04-22 MX MXPA99011835A patent/MXPA99011835A/en active IP Right Grant
- 1999-04-22 EP EP99917115A patent/EP1001477B1/en not_active Expired - Lifetime
Also Published As
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| BR9906385A (en) | 2000-07-11 |
| JP4092669B2 (en) | 2008-05-28 |
| EP1001477B1 (en) | 2009-12-16 |
| CN1149700C (en) | 2004-05-12 |
| MY122229A (en) | 2006-03-31 |
| ATE452434T1 (en) | 2010-01-15 |
| TW419850B (en) | 2001-01-21 |
| DE69941806D1 (en) | 2010-01-28 |
| ID23699A (en) | 2000-05-11 |
| EP1001477A4 (en) | 2005-03-30 |
| JPH11312536A (en) | 1999-11-09 |
| MXPA99011835A (en) | 2002-04-19 |
| EP1001477A1 (en) | 2000-05-17 |
| CA2294292A1 (en) | 1999-11-04 |
| KR100613799B1 (en) | 2006-08-22 |
| KR20010014160A (en) | 2001-02-26 |
| PT1001477E (en) | 2010-01-13 |
| WO1999056337A1 (en) | 1999-11-04 |
| US6506523B1 (en) | 2003-01-14 |
| ID24713A (en) | 2000-08-03 |
| DK1001477T3 (en) | 2010-04-12 |
| CN1266540A (en) | 2000-09-13 |
| ES2338390T3 (en) | 2010-05-06 |
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