CA2247384A1 - Binders for electrodes and their production method - Google Patents
Binders for electrodes and their production method Download PDFInfo
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- CA2247384A1 CA2247384A1 CA002247384A CA2247384A CA2247384A1 CA 2247384 A1 CA2247384 A1 CA 2247384A1 CA 002247384 A CA002247384 A CA 002247384A CA 2247384 A CA2247384 A CA 2247384A CA 2247384 A1 CA2247384 A1 CA 2247384A1
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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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/621—Binders
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F259/00—Macromolecular compounds obtained by polymerising monomers on to polymers of halogen containing monomers as defined in group C08F14/00
- C08F259/02—Macromolecular compounds obtained by polymerising monomers on to polymers of halogen containing monomers as defined in group C08F14/00 on to polymers containing chlorine
- C08F259/06—Macromolecular compounds obtained by polymerising monomers on to polymers of halogen containing monomers as defined in group C08F14/00 on to polymers containing chlorine on to polymers of vinylidene chloride
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D151/00—Coating compositions based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Coating compositions based on derivatives of such polymers
- C09D151/003—Coating compositions based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Coating compositions based on derivatives of such polymers grafted on to macromolecular compounds obtained by reactions only involving unsaturated carbon-to-carbon bonds
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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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Abstract
The present invention relates to electrodes consisting of an electrode activator and a metallic collector whose adhesion between the activator and the collector is improved. The electrode activator's binder is made of a fluoroplastic grafted with at least one acrylic polymer.
Description
W 097/32347 PCTA~P97/W998 SPECIFI~ATIO~
BINDERS FOR ELECTRO~ES AN~ THEIR PRODUCTION METHOD
TECHNICAL FIELD
This invention relates to electrodes which can be used in batteries and cells, such as lithium-ion batteries and cells and the production method of the-said electrodes.
PRIOR ART
There is a great demand for small secondary cells having a high capacity and a long life in portable instruments such as portable telephone sets, video ca"~eras and notebook type personal computers, etc. Lithium-ion cells are future-expectedsecG,lda"~ cells.
Known anode activator suLsLances in the lithium-ion cell consist generally of ca,Lon~ceous materials such as coke or ~~apl,ile into which the lithium ions can be doped or released reversibly (JP-A-62-90863). Usually, a powder of carbonaceous ",~l~rial is mixed with a suitable amount of a binder and is kneaded with a solvent in order to p,e,oare a paste. A collector is then coated with the paste and is dried and cor,~ .led to obtain the anode.
Known cathode activator substances in the lithium-ion cell consist generally of transition metals oxides such as ",an~,~nese oxide and vanadium oxide, sulfides of lld~lsilion metals such as iron sulfide and titanium sulfide, or composite compounds of the above substances and lithium such as composite oxides of lithium and cobalt, co"",osile oxides of lithium, cobalt and nickel, composite oxides of lithium and" ,anyanese. The cathode activator substance also is mixed with an electro-conductive substance (usually carbon) and a suitable amount of a binder and is kneaded with a solvent in order to prepare a paste which is then applied to a collector and is dried and comp~cted to obtain a cathode.
The binder for secondary battery must have a high resistance to liquids which are often used as electrolytes and to active species generated by the electrochemical reactions and also to solvents which are carried out during the manufacture of the batteries and cells. A binder which satisfies the above requirements is polyvinylidenefluoride (PVDF) resin . However PVDF resins and fluorinated resins in general have inherently poor adhesion to metals, so that the activator substance sepal ~es easily from the metallic collector for both cathode and anode and it results that an inferior cycte property of the lithium-ion cell.
JP-A-5-6766 has proposed to roughen the collectors ' surface in order to inc, e~se the anchoring effect of the fluorinated resins. However, a sufficient adhesion cannot be obtained in carrying out this technique.
CONFIF~MAJION COPY
W 097/32347 PCTrEP97/00998 A copolymer of vinylidenefluoride (VF2) and a carboxyl group-containing monomer has been proposed in JP-A-6-172452. This copolymer, however, is difficult to produce industrially.
DISCLOSURE OF THE INVENTION
The present invention provides electrodes for batteries and cells whose adhesion between the electrode activator and the collector is improved so as thecycle property of the cells.
MEANS TO SOLVE THE PROBLEM
The present invention provides electrodes for cells having a layer of an 10 electrode-forming substance comprising an electrode activator and a binder which is coated and/or bonded on a surface of a metallic collector, characterized in that the binder is a fluoroplastic to which at least one acrylic polymer is bonded, the monomer units of the-said acrylic polymer(s) consisting mainly of at least one monomer unit selected from esters of acrylic acid andlor methacrylic acid.
In the grafted fluoroplastic according to the invention, the content of the acrylic polymer is 0.1 to 20 % by weight, preferably 0.2 to 2~ % by weight, moreprererably 0.3 to 5 % by weight of the grafted fluoroplastic. If the content is less than 0,1 % by weight, the adhesion between the electrode activator and the collector is poor; if the content is more than 20 % by weight, the binder's resistance becomes 20 poor and an important swelling caused by the contact with the organic solvents used as electrolytes (for instance ethylenecarbonate, propylenecarbonate, dimethyl carbonate, diethyl carbonate etc) is observed. Consequently both low and high cGnlel-l of acrylic polymer have a bad influence on the performances of the electrodes and of the secondary cells. These drawbacks become particularly serious 25 when the temperature is higher than 50 ~C.
The collector for both electrodes (anode and cathode) may be a metal foil, a metal mesh, a three-dimensional porous block or the like and is prererably made of a metal which does not easily produce an alloy with lithium as iron, nickel, cobalt, copper, titanium, vanadium, chromium and manganese or one of their alloys.
The anode activator substances can be any materials which permit doping and releasing of lithium ions and are generally carbonaceous materials includingcokes such as petroleum cokes and carbon cokes, carbon blacks such as acetylene black, graphite, fibrous carbon, activated carbon, carbon fibers and sintered articles obtained from organic high polymers by burning the organic high polymer in a non-35 oxidative atmosphere. Metal oxides as copper oxide can also be added to the anode activator substance.
W O 97/32347 PCT~EP97/00998 The cathode activator substances can be usual known ones as disclosed above. Some electro-conductive materials can also be incorporated in the cathodeactivator substance.
The fluoroplastic may be polytetrafluoroethylene, polyvinyl fluoride, polytrifluoroethylene, polychlorotrifluoroethylene, copolymer of vinylidenefluoride-chlorotrifluoroethylene, copolymer of ethylene and tetrafluoroethylene, copolymer of tetrafluoroethylene and hexafluoro propylene and polyvinylidenefluoride (PVDF~.
Among them, PVDF is preferably used because of its high resistance to solvents generally used in cells and active species produced and also because of its good10 solubility in N-methylpyrolidone which is generally used during the manufacture of batteries and cells.
For the present invention, PVDF means homopolymers of vinylidenefluoride (VF2) and copolymers of VF2 and at least another fluorinated comonomer preferably chosen among tetrafluoroethylene, hexafluoropropylene, trifluoroethylene and/or 15 chlorotrifluoroethylene that can be used alone or in combination. The amount of VF2 is from 40 to 95 % by weight and preferably from 70 to 95 %. The preferred PVDFsaccording to the present invention have a melt flow index (MFI) of 0.01 to 300 g/10 min at 230 ~C under a load of 2.16 kg.
The main monomer units of the acrylic polymer are, as said above, the esters 20 of acrylic acid andfor methacrylic acid; they may be alkyl esters of acrylic acid or methacrylic acid as methylacrylate, ethylacrylate, methylmethacrylate, ethylmethacrylate and butylmethacrylate. The amount of these monomers in the acryiic polymer(s) is preferably more than ~0 % by weight of the acrylic polymer.
Preferably, the acrylic polymers have 0.2 to 20 parts by weight, preferably 1 to25 10 parts by weight of carboxyl group or carboxyl anhydride groups. The monomers containing carboxyl group or carboxyl anhydride group may be unsaturated carboxylic acids as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, alkenyl succinic acid, acrylamideglycolic acid and monoallyl-1, 2-cyclohexanedicarbonate and unsaturated carboxylic anhydride such as maleic 30 anhydride and alkenyl succinic anhydride.
The acrylic polymers as defined above can be grafted to the fluoroplastic by graft reaction with the help of at least a peroxide effected after the polymerization of the fluoroplastic, by means of radiation or by polymerization of the fluorinatedmonomers (of the-said fluoroplastic) in the presence of the acrylic polymer(s).
The graft reaction with peroxide(s) is carried out in heating a mixture of the acrylic polymer and the fluoroplastic in the presence of the peroxide(s). The reaction can be carried out in molten condition or in a solvent. If a solvent is used, the acryl W O 97/32347 PCTrEP97/00998 polymer, the PVDF and the peroxide(s) are both dissolved in a solvent and the resulting solution is heated at a temperature to which the peroxide decomposes satisfactorily. A suitable amount of peroxide(s) is typically about 0.5 to 10 % by weight to the fluoroplastic. The resulting solution can be applied directly onto a collector to produce the electrode. The graft copolymer can be extracted from the solution by a reprecipitation technique, can be optionally purified by washing with a suitable solvent and used as a binder for the anode and/or the cathode.
Any known peroxides can normally be used as peroxyketals, alkylhydroperoxides, dialkylperoxides, alkylperoxyesters, dialkylperoxides, 10 peroxydicarbonates and peroxyesters.
In the present invention, the graft reaction can be carried out simultaneously with the electrode's manufacture. When the graft reaction occurs with the help of peroxid(s), a slurry can be prepared by kneading predetermined amounts of electrode activator, of fluoroplastic, preferably PVDF as a binder, of the above15 acrylic polymer and peroxide(s~ in the presence of a solvent. The resulting slurry is coated on a surface of the collector, dried and then press-moulded into an electrode.
The slurry is heated before or after its application to the collector according to the peroxide(s~'s nature.
The binder is preferably added in a range from 1 to 30 parts, preferably 3 to 20 15 parts by weight to 100 parts by weight of the electrode activator. Other additives such as electro-conductive agents (copper oxide) also can be added to the electrode-forming substance.
The solvents used during the graft reaction with peroxide(s) or the solvents used to prepare the slurry to be coated on the collector can be water or organic25 solvents such as N-methylpyrolidone, N, N-dimethylformamide, tetrahydrofuran,dimethyl acetoamide, dimethyl sulfoxide, hexamethylsulfolamide, tetramethylurea,acetone and methylethyl ketone. These solvents can be used alone or in combination. Among them, N-methylpyrolidone is preferably used. If necessary, a dispersant can be also be used. Nonionic dispersants are preferred.
ADVANTAGES OF THE INVENTION
The present invention provides electrodes whose adhesion between the electrode activator and the collector is improved. When these electrodes are used in batteries, the capacity of discharge is not deteriorated after repeated charge-discharge cycles. The present invention is useful particularly in lithium-ion cells.
W O 97/32347 PCT~P97/00998 MEANS ~O SOLVE THE INVENTION
Examples Preparation ExamPle 1 10 % by weight of a PVDF homopolymer (sold by Elf Atochem under Kynar~) 500, MFI: 0.03 g/10 min at 230 ~C under a load of 2.16 kg), 0.2 % by weight of an acrylic copolymer (MFI: 2.4 g/10 min at 230 ~C under a load of 3.8 kg, comprising 100 parts by weight of methylmethacrylate and 10 parts by weight of maleic anhydride), and 0.5 % by weight of benzoylperoxide were dissolved in N-methylpyrolidone. The solution was heated at 120 ~C for 30 min and then was poured into methanol to collect the polymer which has precipitated.
The resulting polymer was extracted with chloroform by refluxing the polymer for 6 hours in a Soxhlet extractor to confirm that the acrylic copolymer is grafted to the PVDF. A film prepared with the extracted polymer was examined by IR
spectroscopy; a clear peak at 1740 cm-1 was found that corresponds to the absorption caused by the carbonyl groups.
Preparation ExamPle 2 A grafted PVDF was prepared with the same procedure as in Preparation Example 1 but the PVDF homopolymer was changed to a copolymer of VF2 (90 %
by weight) and hexafluoropr~,ylene (10 % by weight) sold by Elf Atochem under Kynar~)2800 (MFI : 0.2 g/10 min at 230 ~C under a load of 2.16 kg) and benzoylperoxide was changed to t-butylperoxybenzoate.
Preparation ExamPle 3 9 % by weight of the PVDF of Preparation Example 1, 1 % by weight of the copolymer of Preparation Example 2, 0.2 % by weight of the same acrylic polymer of Preparation ~xample 1 and 0.5 % by weight of benzoylperoxide were dissolved in N-methylpyrolidone; the solution was then heated at 120 ~C for 30 minutes and thenwas poured into methanol to collect the polymer which has precipitated.
Example 1 8 parts by weight of the grafted PVDF copolymer of Preparation Example 1 (binder) was dissolved in N-methylpyrolidone and 90 parts by weight of coal pitch coke crushed in a ball mill as anode activator carrier was added to the solution in order to obtain a slurry (paste). The slurry was then coated on both sides of a copper foil of 20 ,um thickness, dried at 120 ~C under reduced pressure and then press-moulded to obtain an anode of 14~ llm thickness and of 20 mm width.
In order to prepare a cathode, 92 parts by weight of LiCoO2 as cathode activator and 6 parts of graphite as electro-conductive additive were dispersed in a solution of N-methylpyrolidone in which 8 parts by weight of the same binder that W 097132347 PCT~EP97/00998 was used for the preparation of the anode was dissolved to obtain a slurry (paste).
The slurry was coated on both sides of an aluminum foil of 20 ,um thickness, dried at 120 ~C under reduced pressure and then press-moulded to obtain anode of 175 ,um thickness and of 20 mm width.
A good adhesion between these electrodes and the electrode activator was noted: the electrode activators remain on the electrode surfaces when the electrode activators deposited on the electrodes were peeled off by a cutter-knife.
The resulting cathode and anode were laminated alternately through a film of porous polypropylene of 25 ,um thickness as separator to form a laminate of 10 separator/cathode/separator/anode/separator which was wound spirally to obtain a cylindrical electrode assembly. After lead wires were attached to respective electrodes, the electrode assembly was packed in a stainless container into which an electrolyte was poured The electrolyte is 1 M solution of LiPF6 dissolved in an equivolumic mixture of propylene carbonate and 1, 2-dimethoxyethane.
In the charge-discharge test, the battery was charged with a current density of 30 mA/ 1 9 of carbon to 4.1 V and then was discharged with the same current to 2.5 V. The same charge-discharge operation was repeated to evaluate the capacity of discharge. The results revealed that the capacity of discharge after 100 cycles was 90 % of a value of 1 0th cycle.
Example 2 8 % by weight of the PVDF used in Preparation Example 1 (Kynar~OO), 0.1 %
by weight of the acrylic polymer used in Preparation Example 1 (binder) and 0.2 parts by weight of diisopropylperoxydicarbonate were dissolved in N-methylpyrolidone. 90 parts by weight of coal pitch coke crushed in a ball mill as 25 anode activator carrier was added to the solution to obtain a slurry (paste). The slurry was heated in a closed system to prevent solvent evaporation at 80 ~C for 30 minutes and then was coated on both sides of a copper foil of 20 ,um thickness, dried at 120 ~C under reduced pressure and then press-moulded to obtain an anode of 140 ,um thickness and of 20 mm width.
In order to prepare a cathode, 92 parts by weight of LiCoO2 as cathode activator and 6 parts of graphite as electro-conductive additive were dispersed in a solution of N-methylpyrolidone in which, as binder, 8 parts by weight of PVDF, 0.1 parts by weight of the acrylic polymer as defined above and and 0.2 parts by weight of diisopropylperoxydicarbonate were dissolved to obtain a slurry (paste). The slurry 35 was heated in a closed system to prevent solvent evaporation at 80 ~C for 30 minutes and then was coated on both sides of a aluminum foil of 20 ,um thickness, .
W O 97/32347 rCT~EP97tO0998 dried at 120 ~C under reduced pressure and then press-moulded to obtain a cathode of 160 ~um thickness and of 20 mm width.
A good adhesion between these electrodes and the electrode activator was noted: each electrode activator remains on the electrode surfaces when the 5 electrode activators deposited on the electrodes were peeled off by a cutter-knife. A
cell was manufactured by the same method as in Example 1 and the same charge-discharge test was effected. The results revealed that the capacity of discharge after 150 cycles was 93 % of a value of 1 0th cycle.
Example 3 The procedure of Example 1 was repeated but the grafted PVDF of Preparation Example 2 was used.
A good adhesion between these electrodes and the electrode activator was noted: the electrode activator remains on the electrode surfaces when the electrode activators deposited on the electrodes were peeled off by a cutter-knife. A cell was manufactured by the same method as in Example 1 and the same charge-discharge test was effected. The results rcvo31cd that the capacity of discharge after 150cycles was 92 % of a value of 1 0th cycle.
Example 4 The procedure of Example 1 was repeated but the grafted PVDF of Preparation Example 3 was used.
A good adhesion between these electrodes and the electrode activator was noted: the electrode activator remains on the electrode surfaces when the electrode activators deposited on the electrodes were peeled off by a cutter-knife. A cell was manufactured by the same method as Example 1 and the same charge-discharge test was effected. Results revealed that the capacity of discharge after 150 cycles was 95 % of a value of 10th cycle.
ComParative ExamPle 1 The same procedure as Example 1 was repeated but PVDF Kynar500 was used.
When carbon pitch coke deposited on electrode was peeled off by a cutter-knife, substantially no electrode activator remains on a surface of the copper electrode. A cell was prepared by using the resulting electrode in the same manner as Example 1 to find that the capacity of discharge after 100 cycles was 50 % of a value of 1 0th cycle.
W O 97132347 PCT~EP97/00998 Comparative ExamPle 2 The same procedure as Example 2 was repeated but no peroxide was added to the slurry for the manufacture of both anode and cathode with the same procedure as in Example 1.
When carbon pitch coke deposited on the electrode was peeled off by a cutter-knife, it was recognized that a substantial part of the electrode activator remains on a surface of copper electrode. A cell was prepared by using the resulting electrode in the same manner as Example 1. Its capacity of discharge after 150 cycles was 5~ % of a value of 1 0th cycle.
BINDERS FOR ELECTRO~ES AN~ THEIR PRODUCTION METHOD
TECHNICAL FIELD
This invention relates to electrodes which can be used in batteries and cells, such as lithium-ion batteries and cells and the production method of the-said electrodes.
PRIOR ART
There is a great demand for small secondary cells having a high capacity and a long life in portable instruments such as portable telephone sets, video ca"~eras and notebook type personal computers, etc. Lithium-ion cells are future-expectedsecG,lda"~ cells.
Known anode activator suLsLances in the lithium-ion cell consist generally of ca,Lon~ceous materials such as coke or ~~apl,ile into which the lithium ions can be doped or released reversibly (JP-A-62-90863). Usually, a powder of carbonaceous ",~l~rial is mixed with a suitable amount of a binder and is kneaded with a solvent in order to p,e,oare a paste. A collector is then coated with the paste and is dried and cor,~ .led to obtain the anode.
Known cathode activator substances in the lithium-ion cell consist generally of transition metals oxides such as ",an~,~nese oxide and vanadium oxide, sulfides of lld~lsilion metals such as iron sulfide and titanium sulfide, or composite compounds of the above substances and lithium such as composite oxides of lithium and cobalt, co"",osile oxides of lithium, cobalt and nickel, composite oxides of lithium and" ,anyanese. The cathode activator substance also is mixed with an electro-conductive substance (usually carbon) and a suitable amount of a binder and is kneaded with a solvent in order to prepare a paste which is then applied to a collector and is dried and comp~cted to obtain a cathode.
The binder for secondary battery must have a high resistance to liquids which are often used as electrolytes and to active species generated by the electrochemical reactions and also to solvents which are carried out during the manufacture of the batteries and cells. A binder which satisfies the above requirements is polyvinylidenefluoride (PVDF) resin . However PVDF resins and fluorinated resins in general have inherently poor adhesion to metals, so that the activator substance sepal ~es easily from the metallic collector for both cathode and anode and it results that an inferior cycte property of the lithium-ion cell.
JP-A-5-6766 has proposed to roughen the collectors ' surface in order to inc, e~se the anchoring effect of the fluorinated resins. However, a sufficient adhesion cannot be obtained in carrying out this technique.
CONFIF~MAJION COPY
W 097/32347 PCTrEP97/00998 A copolymer of vinylidenefluoride (VF2) and a carboxyl group-containing monomer has been proposed in JP-A-6-172452. This copolymer, however, is difficult to produce industrially.
DISCLOSURE OF THE INVENTION
The present invention provides electrodes for batteries and cells whose adhesion between the electrode activator and the collector is improved so as thecycle property of the cells.
MEANS TO SOLVE THE PROBLEM
The present invention provides electrodes for cells having a layer of an 10 electrode-forming substance comprising an electrode activator and a binder which is coated and/or bonded on a surface of a metallic collector, characterized in that the binder is a fluoroplastic to which at least one acrylic polymer is bonded, the monomer units of the-said acrylic polymer(s) consisting mainly of at least one monomer unit selected from esters of acrylic acid andlor methacrylic acid.
In the grafted fluoroplastic according to the invention, the content of the acrylic polymer is 0.1 to 20 % by weight, preferably 0.2 to 2~ % by weight, moreprererably 0.3 to 5 % by weight of the grafted fluoroplastic. If the content is less than 0,1 % by weight, the adhesion between the electrode activator and the collector is poor; if the content is more than 20 % by weight, the binder's resistance becomes 20 poor and an important swelling caused by the contact with the organic solvents used as electrolytes (for instance ethylenecarbonate, propylenecarbonate, dimethyl carbonate, diethyl carbonate etc) is observed. Consequently both low and high cGnlel-l of acrylic polymer have a bad influence on the performances of the electrodes and of the secondary cells. These drawbacks become particularly serious 25 when the temperature is higher than 50 ~C.
The collector for both electrodes (anode and cathode) may be a metal foil, a metal mesh, a three-dimensional porous block or the like and is prererably made of a metal which does not easily produce an alloy with lithium as iron, nickel, cobalt, copper, titanium, vanadium, chromium and manganese or one of their alloys.
The anode activator substances can be any materials which permit doping and releasing of lithium ions and are generally carbonaceous materials includingcokes such as petroleum cokes and carbon cokes, carbon blacks such as acetylene black, graphite, fibrous carbon, activated carbon, carbon fibers and sintered articles obtained from organic high polymers by burning the organic high polymer in a non-35 oxidative atmosphere. Metal oxides as copper oxide can also be added to the anode activator substance.
W O 97/32347 PCT~EP97/00998 The cathode activator substances can be usual known ones as disclosed above. Some electro-conductive materials can also be incorporated in the cathodeactivator substance.
The fluoroplastic may be polytetrafluoroethylene, polyvinyl fluoride, polytrifluoroethylene, polychlorotrifluoroethylene, copolymer of vinylidenefluoride-chlorotrifluoroethylene, copolymer of ethylene and tetrafluoroethylene, copolymer of tetrafluoroethylene and hexafluoro propylene and polyvinylidenefluoride (PVDF~.
Among them, PVDF is preferably used because of its high resistance to solvents generally used in cells and active species produced and also because of its good10 solubility in N-methylpyrolidone which is generally used during the manufacture of batteries and cells.
For the present invention, PVDF means homopolymers of vinylidenefluoride (VF2) and copolymers of VF2 and at least another fluorinated comonomer preferably chosen among tetrafluoroethylene, hexafluoropropylene, trifluoroethylene and/or 15 chlorotrifluoroethylene that can be used alone or in combination. The amount of VF2 is from 40 to 95 % by weight and preferably from 70 to 95 %. The preferred PVDFsaccording to the present invention have a melt flow index (MFI) of 0.01 to 300 g/10 min at 230 ~C under a load of 2.16 kg.
The main monomer units of the acrylic polymer are, as said above, the esters 20 of acrylic acid andfor methacrylic acid; they may be alkyl esters of acrylic acid or methacrylic acid as methylacrylate, ethylacrylate, methylmethacrylate, ethylmethacrylate and butylmethacrylate. The amount of these monomers in the acryiic polymer(s) is preferably more than ~0 % by weight of the acrylic polymer.
Preferably, the acrylic polymers have 0.2 to 20 parts by weight, preferably 1 to25 10 parts by weight of carboxyl group or carboxyl anhydride groups. The monomers containing carboxyl group or carboxyl anhydride group may be unsaturated carboxylic acids as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, alkenyl succinic acid, acrylamideglycolic acid and monoallyl-1, 2-cyclohexanedicarbonate and unsaturated carboxylic anhydride such as maleic 30 anhydride and alkenyl succinic anhydride.
The acrylic polymers as defined above can be grafted to the fluoroplastic by graft reaction with the help of at least a peroxide effected after the polymerization of the fluoroplastic, by means of radiation or by polymerization of the fluorinatedmonomers (of the-said fluoroplastic) in the presence of the acrylic polymer(s).
The graft reaction with peroxide(s) is carried out in heating a mixture of the acrylic polymer and the fluoroplastic in the presence of the peroxide(s). The reaction can be carried out in molten condition or in a solvent. If a solvent is used, the acryl W O 97/32347 PCTrEP97/00998 polymer, the PVDF and the peroxide(s) are both dissolved in a solvent and the resulting solution is heated at a temperature to which the peroxide decomposes satisfactorily. A suitable amount of peroxide(s) is typically about 0.5 to 10 % by weight to the fluoroplastic. The resulting solution can be applied directly onto a collector to produce the electrode. The graft copolymer can be extracted from the solution by a reprecipitation technique, can be optionally purified by washing with a suitable solvent and used as a binder for the anode and/or the cathode.
Any known peroxides can normally be used as peroxyketals, alkylhydroperoxides, dialkylperoxides, alkylperoxyesters, dialkylperoxides, 10 peroxydicarbonates and peroxyesters.
In the present invention, the graft reaction can be carried out simultaneously with the electrode's manufacture. When the graft reaction occurs with the help of peroxid(s), a slurry can be prepared by kneading predetermined amounts of electrode activator, of fluoroplastic, preferably PVDF as a binder, of the above15 acrylic polymer and peroxide(s~ in the presence of a solvent. The resulting slurry is coated on a surface of the collector, dried and then press-moulded into an electrode.
The slurry is heated before or after its application to the collector according to the peroxide(s~'s nature.
The binder is preferably added in a range from 1 to 30 parts, preferably 3 to 20 15 parts by weight to 100 parts by weight of the electrode activator. Other additives such as electro-conductive agents (copper oxide) also can be added to the electrode-forming substance.
The solvents used during the graft reaction with peroxide(s) or the solvents used to prepare the slurry to be coated on the collector can be water or organic25 solvents such as N-methylpyrolidone, N, N-dimethylformamide, tetrahydrofuran,dimethyl acetoamide, dimethyl sulfoxide, hexamethylsulfolamide, tetramethylurea,acetone and methylethyl ketone. These solvents can be used alone or in combination. Among them, N-methylpyrolidone is preferably used. If necessary, a dispersant can be also be used. Nonionic dispersants are preferred.
ADVANTAGES OF THE INVENTION
The present invention provides electrodes whose adhesion between the electrode activator and the collector is improved. When these electrodes are used in batteries, the capacity of discharge is not deteriorated after repeated charge-discharge cycles. The present invention is useful particularly in lithium-ion cells.
W O 97/32347 PCT~P97/00998 MEANS ~O SOLVE THE INVENTION
Examples Preparation ExamPle 1 10 % by weight of a PVDF homopolymer (sold by Elf Atochem under Kynar~) 500, MFI: 0.03 g/10 min at 230 ~C under a load of 2.16 kg), 0.2 % by weight of an acrylic copolymer (MFI: 2.4 g/10 min at 230 ~C under a load of 3.8 kg, comprising 100 parts by weight of methylmethacrylate and 10 parts by weight of maleic anhydride), and 0.5 % by weight of benzoylperoxide were dissolved in N-methylpyrolidone. The solution was heated at 120 ~C for 30 min and then was poured into methanol to collect the polymer which has precipitated.
The resulting polymer was extracted with chloroform by refluxing the polymer for 6 hours in a Soxhlet extractor to confirm that the acrylic copolymer is grafted to the PVDF. A film prepared with the extracted polymer was examined by IR
spectroscopy; a clear peak at 1740 cm-1 was found that corresponds to the absorption caused by the carbonyl groups.
Preparation ExamPle 2 A grafted PVDF was prepared with the same procedure as in Preparation Example 1 but the PVDF homopolymer was changed to a copolymer of VF2 (90 %
by weight) and hexafluoropr~,ylene (10 % by weight) sold by Elf Atochem under Kynar~)2800 (MFI : 0.2 g/10 min at 230 ~C under a load of 2.16 kg) and benzoylperoxide was changed to t-butylperoxybenzoate.
Preparation ExamPle 3 9 % by weight of the PVDF of Preparation Example 1, 1 % by weight of the copolymer of Preparation Example 2, 0.2 % by weight of the same acrylic polymer of Preparation ~xample 1 and 0.5 % by weight of benzoylperoxide were dissolved in N-methylpyrolidone; the solution was then heated at 120 ~C for 30 minutes and thenwas poured into methanol to collect the polymer which has precipitated.
Example 1 8 parts by weight of the grafted PVDF copolymer of Preparation Example 1 (binder) was dissolved in N-methylpyrolidone and 90 parts by weight of coal pitch coke crushed in a ball mill as anode activator carrier was added to the solution in order to obtain a slurry (paste). The slurry was then coated on both sides of a copper foil of 20 ,um thickness, dried at 120 ~C under reduced pressure and then press-moulded to obtain an anode of 14~ llm thickness and of 20 mm width.
In order to prepare a cathode, 92 parts by weight of LiCoO2 as cathode activator and 6 parts of graphite as electro-conductive additive were dispersed in a solution of N-methylpyrolidone in which 8 parts by weight of the same binder that W 097132347 PCT~EP97/00998 was used for the preparation of the anode was dissolved to obtain a slurry (paste).
The slurry was coated on both sides of an aluminum foil of 20 ,um thickness, dried at 120 ~C under reduced pressure and then press-moulded to obtain anode of 175 ,um thickness and of 20 mm width.
A good adhesion between these electrodes and the electrode activator was noted: the electrode activators remain on the electrode surfaces when the electrode activators deposited on the electrodes were peeled off by a cutter-knife.
The resulting cathode and anode were laminated alternately through a film of porous polypropylene of 25 ,um thickness as separator to form a laminate of 10 separator/cathode/separator/anode/separator which was wound spirally to obtain a cylindrical electrode assembly. After lead wires were attached to respective electrodes, the electrode assembly was packed in a stainless container into which an electrolyte was poured The electrolyte is 1 M solution of LiPF6 dissolved in an equivolumic mixture of propylene carbonate and 1, 2-dimethoxyethane.
In the charge-discharge test, the battery was charged with a current density of 30 mA/ 1 9 of carbon to 4.1 V and then was discharged with the same current to 2.5 V. The same charge-discharge operation was repeated to evaluate the capacity of discharge. The results revealed that the capacity of discharge after 100 cycles was 90 % of a value of 1 0th cycle.
Example 2 8 % by weight of the PVDF used in Preparation Example 1 (Kynar~OO), 0.1 %
by weight of the acrylic polymer used in Preparation Example 1 (binder) and 0.2 parts by weight of diisopropylperoxydicarbonate were dissolved in N-methylpyrolidone. 90 parts by weight of coal pitch coke crushed in a ball mill as 25 anode activator carrier was added to the solution to obtain a slurry (paste). The slurry was heated in a closed system to prevent solvent evaporation at 80 ~C for 30 minutes and then was coated on both sides of a copper foil of 20 ,um thickness, dried at 120 ~C under reduced pressure and then press-moulded to obtain an anode of 140 ,um thickness and of 20 mm width.
In order to prepare a cathode, 92 parts by weight of LiCoO2 as cathode activator and 6 parts of graphite as electro-conductive additive were dispersed in a solution of N-methylpyrolidone in which, as binder, 8 parts by weight of PVDF, 0.1 parts by weight of the acrylic polymer as defined above and and 0.2 parts by weight of diisopropylperoxydicarbonate were dissolved to obtain a slurry (paste). The slurry 35 was heated in a closed system to prevent solvent evaporation at 80 ~C for 30 minutes and then was coated on both sides of a aluminum foil of 20 ,um thickness, .
W O 97/32347 rCT~EP97tO0998 dried at 120 ~C under reduced pressure and then press-moulded to obtain a cathode of 160 ~um thickness and of 20 mm width.
A good adhesion between these electrodes and the electrode activator was noted: each electrode activator remains on the electrode surfaces when the 5 electrode activators deposited on the electrodes were peeled off by a cutter-knife. A
cell was manufactured by the same method as in Example 1 and the same charge-discharge test was effected. The results revealed that the capacity of discharge after 150 cycles was 93 % of a value of 1 0th cycle.
Example 3 The procedure of Example 1 was repeated but the grafted PVDF of Preparation Example 2 was used.
A good adhesion between these electrodes and the electrode activator was noted: the electrode activator remains on the electrode surfaces when the electrode activators deposited on the electrodes were peeled off by a cutter-knife. A cell was manufactured by the same method as in Example 1 and the same charge-discharge test was effected. The results rcvo31cd that the capacity of discharge after 150cycles was 92 % of a value of 1 0th cycle.
Example 4 The procedure of Example 1 was repeated but the grafted PVDF of Preparation Example 3 was used.
A good adhesion between these electrodes and the electrode activator was noted: the electrode activator remains on the electrode surfaces when the electrode activators deposited on the electrodes were peeled off by a cutter-knife. A cell was manufactured by the same method as Example 1 and the same charge-discharge test was effected. Results revealed that the capacity of discharge after 150 cycles was 95 % of a value of 10th cycle.
ComParative ExamPle 1 The same procedure as Example 1 was repeated but PVDF Kynar500 was used.
When carbon pitch coke deposited on electrode was peeled off by a cutter-knife, substantially no electrode activator remains on a surface of the copper electrode. A cell was prepared by using the resulting electrode in the same manner as Example 1 to find that the capacity of discharge after 100 cycles was 50 % of a value of 1 0th cycle.
W O 97132347 PCT~EP97/00998 Comparative ExamPle 2 The same procedure as Example 2 was repeated but no peroxide was added to the slurry for the manufacture of both anode and cathode with the same procedure as in Example 1.
When carbon pitch coke deposited on the electrode was peeled off by a cutter-knife, it was recognized that a substantial part of the electrode activator remains on a surface of copper electrode. A cell was prepared by using the resulting electrode in the same manner as Example 1. Its capacity of discharge after 150 cycles was 5~ % of a value of 1 0th cycle.
Claims (10)
1. Electrode for cell comprising a layer of an electrode-forming substance comprising an electrode activator and a binder coated or bonded to a surface of a collector, characterized in that the binder is a fluoroplastic grafted with at least one acryl polymer consisting mainly of at least one monomer unit selected from esters of acrylic acid and/or methacrylic acid and that the content of said acryl polymeris 0.1 to 20 % by weight of the-said binder.
2. Electrode according to claim 1, wherein said the fluoroplastic is a PVDF resin.
3. Electrode according to claim 2, wherein the-said PVDF resin is a PVDF
homopolymer.
homopolymer.
4. Electrode according to claim 2, wherein wherein the-said PVDF resin is a copolymer of vinylidenefluoride and at least one monomer selected from the group comprising tetrafluoroethylene, hexafluoropropylene, trifluoroethylene and/or chlorotrifluoroethylene, the proportion of vinylidenefluoride in the copolymer being more than 40 % by weight.
5. Electrode according to claim 2, wherein said the-said PVDF resin is a mixture of a PVDF homopolymer and a copolymer of vinylidenefluoride and at leastone monomer selected from the group comprising tetrafluoroethylene, hexafluoropropylene, trifluoroethylene and/or chlorotrifluoroethylene, the proportion of vinylidenefluoride in the copolymer being from 50 to 95 % by weight.
6. Electrode according to any of claims 1 to 5, wherein the acrylic polymer comprises 0.5 to 20 % by weight of at least one monomer having carboxylic acid and/or carboxylic anhydride group.
7. Method for the production of an electrode as defined in any claims 1 to 6, wherein the binder is obtained by graft reaction of the acrylic polymer(s) and the fluoroplastic in the presence of peroxide(s) then is kneaded with the electrode activator in the presence of a solvent to prepare a slurry, the-said slurry is then applied on the surface of a collector which is finally dried.
8. Method for the production of an electrode as defined in any claims 1 to 6, wherein a slurry is prepared from a solution of the fluorinated monomers, theacrylic polymer(s) and the peroxide(s) in a solvent and the-said slurry is coated to a collector after having been heated to a temperature suitable for the polymerization and the graft reactions of the fluoroplastic.
9. Method for the production of an electrode as defined in any claims 1 to 6, wherein a slurry is prepared from a slurry of the fluorinated monomers, the acrylic polymer(s) and the peroxide(s) in a solvent and the-said slurry is coated to a collector which is then heated to a temperature suitable for the polymerization and the graft reactions of the fmluoroplastic.
10. Method for the production of an electrode as defined in any claims 1 to 6, wherein the binder is obtained by graft reaction of the acrylic polymer(s) and the fluoroplastic by means of radiation.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8/39672 | 1996-02-27 | ||
| JP8039672A JPH09231977A (en) | 1996-02-27 | 1996-02-27 | Electrode and its manufacture |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2247384A1 true CA2247384A1 (en) | 1997-09-04 |
Family
ID=12559598
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002247384A Abandoned CA2247384A1 (en) | 1996-02-27 | 1997-02-27 | Binders for electrodes and their production method |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US6228533B1 (en) |
| EP (1) | EP0883902B1 (en) |
| JP (1) | JPH09231977A (en) |
| KR (1) | KR19990087243A (en) |
| CN (1) | CN1212076A (en) |
| AT (1) | ATE193787T1 (en) |
| AU (1) | AU2023297A (en) |
| CA (1) | CA2247384A1 (en) |
| DE (1) | DE69702243T2 (en) |
| WO (1) | WO1997032347A1 (en) |
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| EP0911347B1 (en) * | 1997-10-15 | 2006-08-23 | E.I. Du Pont De Nemours And Company | Copolymers of maleic anhydride or acid and fluorinated olefins |
| JPH11228902A (en) * | 1998-02-17 | 1999-08-24 | Elf Atochem Japan Kk | Method for bonding vinylidene fluoride resin to metal substrate, electrode structure, and method for producing same |
| KR100346542B1 (en) * | 1999-01-25 | 2002-07-26 | 삼성에스디아이 주식회사 | Lithium secondary battery |
| US7064472B2 (en) * | 1999-07-20 | 2006-06-20 | Sri International | Electroactive polymer devices for moving fluid |
| FR2807212A1 (en) * | 2000-03-31 | 2001-10-05 | Atofina | STRUCTURE COMPRISING A FLUORINE PRIMER AND ELECTRODE BASED ON SAID STRUCTURE |
| JP2002134113A (en) * | 2000-10-30 | 2002-05-10 | Matsushita Electric Ind Co Ltd | Non-aqueous secondary battery |
| JP2002246029A (en) * | 2001-02-20 | 2002-08-30 | Atofina Japan Kk | Binder composition |
| JP4390397B2 (en) * | 2001-02-28 | 2009-12-24 | 三洋電機株式会社 | Method for producing alkaline storage battery electrode |
| WO2002084764A1 (en) | 2001-04-10 | 2002-10-24 | Mitsubishi Materials Corporation | Lithium ion polymer secondary battery, its electrode and method for synthesizing polymer compound in binder used in adhesion layer thereof |
| RU2218359C2 (en) * | 2002-02-27 | 2003-12-10 | Самсунг Сди Ко., Лтд. | Fluorinated graft copolymer, polymeric electrolyte containing this copolymer, lithium accumulator battery with the polymeric electrolyte |
| JP3661945B2 (en) * | 2002-07-24 | 2005-06-22 | ソニー株式会社 | Positive electrode for secondary battery and secondary battery provided with the same |
| JP2004220911A (en) * | 2003-01-15 | 2004-08-05 | Mitsubishi Materials Corp | Anode material for lithium polymer battery, anode using the same, lithium ion battery and lithium polymer battery using the anode |
| US7611549B2 (en) * | 2003-12-22 | 2009-11-03 | Cardiac Pacemakers, Inc. | Magnetic stacking fixture for stacking electrodes |
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| US7952261B2 (en) | 2007-06-29 | 2011-05-31 | Bayer Materialscience Ag | Electroactive polymer transducers for sensory feedback applications |
| CN101478036B (en) * | 2008-01-04 | 2011-06-08 | 陈风 | Manufacturing process for battery pole piece |
| US8017273B2 (en) | 2008-04-28 | 2011-09-13 | Ut-Battelle Llc | Lightweight, durable lead-acid batteries |
| EP2239793A1 (en) | 2009-04-11 | 2010-10-13 | Bayer MaterialScience AG | Electrically switchable polymer film structure and use thereof |
| JP5697906B2 (en) * | 2010-06-24 | 2015-04-08 | 株式会社日本触媒 | Electrode aqueous composition for secondary battery |
| WO2012084578A1 (en) | 2010-12-22 | 2012-06-28 | Solvay Specialty Polymers Italy S.P.A. | Vinylidene fluoride copolymers |
| KR101826388B1 (en) | 2010-12-22 | 2018-02-06 | 솔베이 스페셜티 폴리머스 이태리 에스.피.에이. | Vinylidene fluoride and trifluoroethylene polymers |
| WO2012118916A2 (en) | 2011-03-01 | 2012-09-07 | Bayer Materialscience Ag | Automated manufacturing processes for producing deformable polymer devices and films |
| JP2014517331A (en) | 2011-03-22 | 2014-07-17 | バイエル・インテレクチュアル・プロパティ・ゲゼルシャフト・ミット・ベシュレンクテル・ハフツング | Electric field responsive polymer actuator lenticular system |
| 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 |
| US9876160B2 (en) | 2012-03-21 | 2018-01-23 | Parker-Hannifin Corporation | Roll-to-roll manufacturing processes for producing self-healing electroactive polymer devices |
| KR20150031285A (en) | 2012-06-18 | 2015-03-23 | 바이엘 인텔렉쳐 프로퍼티 게엠베하 | Stretch frame for stretching process |
| US9590193B2 (en) | 2012-10-24 | 2017-03-07 | Parker-Hannifin Corporation | Polymer diode |
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| US9385374B2 (en) | 2014-04-01 | 2016-07-05 | Ppg Industries Ohio, Inc. | Electrode binder composition for lithium ion electrical storage devices |
| CN107078267B (en) * | 2014-05-07 | 2021-05-07 | 索尔维公司 | Composite electrode |
| DE102015215451A1 (en) * | 2015-08-13 | 2017-02-16 | Bayerische Motoren Werke Aktiengesellschaft | electrode binders |
| FR3044012B1 (en) | 2015-11-24 | 2019-04-05 | Arkema France | BINDER FOR ATTACHING MATERIAL CONTAINING VINYLIDENE POLYFLUORIDE TO A METAL - ELECTRODE FOR LITHIUM ION BATTERY |
| CN106941149A (en) * | 2016-01-04 | 2017-07-11 | 宁德新能源科技有限公司 | Lithium-ion battery and its positive pole piece |
| CN105514488B (en) * | 2016-01-19 | 2018-11-02 | 宁德新能源科技有限公司 | A kind of binder and its lithium ion battery |
| CN108172836B (en) * | 2017-12-29 | 2020-03-24 | 山东华夏神舟新材料有限公司 | Preparation method of polyvinylidene fluoride modified composite conductive adhesive |
| FR3106702B1 (en) * | 2020-01-29 | 2022-10-07 | Arkema France | ELECTRODE FORMULATION FOR LI-ION BATTERY AND SOLVENTLESS ELECTRODE MANUFACTURING METHOD |
| CN112103509B (en) * | 2020-08-20 | 2023-06-06 | 欣旺达电动汽车电池有限公司 | Positive electrode current collector, positive electrode plate, lithium ion battery and battery module |
| KR102864401B1 (en) * | 2021-03-26 | 2025-09-24 | 주식회사 엘지에너지솔루션 | Positive electrode and lithium secondary battery |
| JP2024516671A (en) * | 2021-04-29 | 2024-04-16 | アーケマ・インコーポレイテッド | Blends of fluoropolymers and functional acrylic polymers as binders for electrochemical devices. |
| CN118765291A (en) * | 2022-11-04 | 2024-10-11 | 宁德时代新能源科技股份有限公司 | Fluorine-containing polymer, primer slurry, secondary battery, and electrical device |
| WO2025082898A1 (en) | 2023-10-16 | 2025-04-24 | Solvay Specialty Polymers Italy S.P.A. | Secondary batteries electrode binders |
| CN119208619B (en) * | 2024-11-29 | 2025-04-01 | 河南烯力新材料科技有限公司 | A modified current collector and its preparation method and application |
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|---|---|---|---|---|
| FR2478649B1 (en) * | 1980-03-21 | 1985-06-21 | Ugine Kuhlmann | VINYLIDENE POLYFLUORIDE TREATED FOR ADHESION ON METALS, PROCESS FOR TREATMENT |
| JPS58133309A (en) * | 1982-02-01 | 1983-08-09 | Daido Steel Co Ltd | Method and apparatus for iron manufacture employing twin reactor |
| JPS6290863A (en) | 1985-05-10 | 1987-04-25 | Asahi Chem Ind Co Ltd | Secondary cell |
| JPH02166107A (en) * | 1988-12-19 | 1990-06-26 | Hitachi Chem Co Ltd | Production of graft copolymer and coating material |
| JP3182786B2 (en) | 1990-11-27 | 2001-07-03 | ソニー株式会社 | Battery |
| JP3121943B2 (en) * | 1992-12-02 | 2001-01-09 | 呉羽化学工業株式会社 | Vinylidene fluoride copolymer |
| EP0633618B1 (en) * | 1992-12-25 | 2000-03-22 | TDK Corporation | Lithium secondary cell |
| US5567539A (en) * | 1994-05-23 | 1996-10-22 | Fuji Photo Film Co., Ltd. | Non-aqueous secondary cell |
| DE69700138T2 (en) * | 1996-01-31 | 1999-09-02 | Aea Technology Plc | Polyvinylidene fluoride as a polymeric solid electrolyte for lithium-ion batteries |
-
1996
- 1996-02-27 JP JP8039672A patent/JPH09231977A/en active Pending
-
1997
- 1997-02-27 DE DE69702243T patent/DE69702243T2/en not_active Expired - Fee Related
- 1997-02-27 CA CA002247384A patent/CA2247384A1/en not_active Abandoned
- 1997-02-27 KR KR1019980706644A patent/KR19990087243A/en not_active Ceased
- 1997-02-27 WO PCT/EP1997/000998 patent/WO1997032347A1/en not_active Ceased
- 1997-02-27 AT AT97908157T patent/ATE193787T1/en not_active IP Right Cessation
- 1997-02-27 EP EP97908157A patent/EP0883902B1/en not_active Expired - Lifetime
- 1997-02-27 US US09/125,444 patent/US6228533B1/en not_active Expired - Fee Related
- 1997-02-27 AU AU20232/97A patent/AU2023297A/en not_active Abandoned
- 1997-02-27 CN CN97192588A patent/CN1212076A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPH09231977A (en) | 1997-09-05 |
| DE69702243D1 (en) | 2000-07-13 |
| KR19990087243A (en) | 1999-12-15 |
| US6228533B1 (en) | 2001-05-08 |
| CN1212076A (en) | 1999-03-24 |
| EP0883902A1 (en) | 1998-12-16 |
| AU2023297A (en) | 1997-09-16 |
| EP0883902B1 (en) | 2000-06-07 |
| WO1997032347A1 (en) | 1997-09-04 |
| ATE193787T1 (en) | 2000-06-15 |
| DE69702243T2 (en) | 2000-12-28 |
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| EEER | Examination request | ||
| FZDE | Discontinued |