Classifications

• • 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
• • 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
• • 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
  • H01M4/622—Binders being polymers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/10—Primary casings; Jackets or wrappings
  • H01M50/102—Primary casings; Jackets or wrappings characterised by their shape or physical structure
  • H01M50/103—Primary casings; Jackets or wrappings characterised by their shape or physical structure prismatic or rectangular
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/411—Organic material
  • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/411—Organic material
  • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
  • H01M50/42—Acrylic resins
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/411—Organic material
  • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
  • H01M50/426—Fluorocarbon polymers
• • 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
  • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
  • H01M2010/4292—Aspects relating to capacity ratio of electrodes/electrolyte or anode/cathode
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0065—Solid electrolytes
  • H01M2300/0082—Organic polymers
• • 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
• • 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

Definitions

• the present invention comprises a positive electrode containing a lithium-containing composite oxide, a negative electrode containing a material capable of inserting and removing lithium ions, and a separator interposed between the positive electrode and the negative electrode.
• Each of the separators relates to a lithium polymer secondary battery containing a polymer electrolyte.
• Lithium ion secondary batteries that use lithium-containing composite oxides as positive electrode materials, carbon materials as negative electrode materials, and liquid nonaqueous electrolytes have higher voltages and lower energy densities than aqueous secondary batteries. High and excellent in low temperature characteristics. In addition, lithium-ion secondary batteries have excellent cycle life and safety because they do not use lithium metal for the negative electrode, and are being rapidly commercialized.
• a lithium polymer secondary battery containing a gel polymer electrolyte has a problem that cycle stability is inferior to a lithium ion secondary battery containing a liquid non-aqueous electrolyte.
• the capacity at the 100th cycle may drop to about 80% of the initial value. is there. This deterioration is lower than that of lithium ion secondary batteries. It is very big.
• JP-A-3-171567 discloses an ethylene oxide-based polymer having excellent compatibility with a non-aqueous electrolyte.
• ethylene oxide polymers have a problem in thermal stability due to sol / gel transition at high temperatures.
• JP-A-4-306560 discloses a polyacrylonitrile-based material which is flame-retardant and exhibits high ionic conductivity.
• non-aqueous solvents having good compatibility with polyacrylonitrile-based materials are limited, and there is a problem in the thermal stability of the obtained gel.
• US Patent No. 5,296,318 discloses a vinylidene fluoride polymer that is electrochemically stable and has excellent flame retardancy.
• the vinylidene fluoride polymer has a problem that it has a low affinity for a non-aqueous solvent at a high temperature.
• Japanese Patent Application Laid-Open No. 55-35420 discloses a polyacrylate-based material excellent in holding a non-aqueous solvent.
• polyacrylate materials are said to be electrochemically unstable.
• the present invention improves the cycle stability of a lithium polymer primary battery by optimizing the distribution of the polymer material contained in the positive electrode, the negative electrode, and the separator.
• the present invention provides a lithium polymer battery comprising a positive electrode containing a lithium-containing composite oxide, a negative electrode containing a material capable of inserting and removing lithium ions, and a separator interposed between the positive electrode and the negative electrode.
• the positive electrode, the negative electrode and the separator include a polymer material, a non-aqueous solvent, and a polymer electrolyte composed of a solvent.
• the weight of the polymer material contained in the positive electrode is Wp
• the weight of the polymer material contained in the negative electrode is Wn
• the weight of the polymer material contained in the separator is Ws
• the material into which lithium ions can be inserted and desorbed is preferably at least one selected from the group consisting of carbon materials, alloys, oxides, and nitrides.
• the polymer material is preferably composed of a polymer containing at least one of an acrylate unit and a methacrylate unit and an alkylene oxide unit, a polyurethane having a carbonate group, or a polymer containing a vinylidene fluoride unit. These may be used alone or in combination of two or more.
• the polymer electrolyte contained in the positive electrode, the negative electrode and the separator is preferably made of the same or similar polymer material.
• the positive electrode, the negative electrode, and Separete are all copolymers of vinylidene fluoride and hexafluoropropylene.
• it preferably contains a polymer having a structure very similar to this.
• a polymer material refers to a polymer material constituting a polymer electrolyte, and is distinguished from a material having another function.
• a polymer material that constitutes the polymer electrolyte and also functions as a binder for the active material is treated as a polymer material that constitutes the polymer electrolyte.
• FIG. 1 is a longitudinal sectional view of an example of the lithium polymer secondary battery of the present invention.
• lithium ion secondary batteries do not include polymer materials that are compatible with non-aqueous solvents.
• polymer materials that do not dissolve or swell in non-aqueous solvents are used as binder / separator materials contained in the positive and negative electrodes of lithium ion secondary batteries. Therefore, these materials do not affect the distribution of the liquid non-aqueous electrolyte.
• the distribution of the non-aqueous electrolyte composed of the non-aqueous solvent and the solute is high due to the high affinity between the polymer material that constitutes the polymer electrolyte and the non-aqueous solvent. Affected by That is, since the polymer material absorbs the non-aqueous electrolyte and swells, if the polymer material is distributed too much in a particular battery element, the non-aqueous electrolyte is localized in that element. As a result, in other elements, the nonaqueous solvent is locally depleted, and the charge / discharge reaction is inhibited. Further, when the electrode is excessively swollen with the non-aqueous solvent, there is a problem that the conductive network in the electrode is broken, the active material particles are released, and the battery capacity is reduced.
• the electrode plate expands and contracts with a charge / discharge reaction.
• it is effective to include a certain amount of a polymer material in the negative electrode.
• the polymer material that composes the polymer electrolyte is- The swelling with the non-aqueous solvent promotes the expansion of the electrode plate, which causes a problem that the cycle characteristics of the battery are deteriorated.
• the weight Wp of the polymer material constituting the polymer electrolyte contained in the positive electrode, the weight Wn of the polymer material constituting the polymer electrolyte contained in the negative electrode, and the separation are included.
• the weight W s of the polymer material constituting the polymer electrolyte is
• the distribution of the polymer material constituting the polymer electrolyte in the battery is optimized, the localization of the non-aqueous electrolyte is suppressed, and the lithium polymer secondary battery The cycle characteristics are also improved.
• the effect of equalizing the distribution of the non-aqueous electrolyte in the battery is due to the fact that the polymer electrolyte contained in the positive electrode, the negative electrode and the separator is based on the weight of the polymer material constituting the entire polymer electrolyte contained in the positive electrode, the negative electrode and the separator.
• the proportion of the weight of the polymer material By controlling the proportion of the weight of the polymer material to be 20 to 45% by weight, respectively, it becomes even larger.
• FIG. 1 is a longitudinal sectional view of an example of a flat lithium polymer secondary battery.
• This battery includes a stack of electrode plates and a flat battery case 1.
• a laminate film in which an aluminum foil is disposed between resin films is generally used.
• the opening of the battery case 1 is sealed with an adhesive resin 2.
• a thermoplastic resin which is melted by heating or a thermosetting resin is preferably used.
• An electrode plate group composed of a negative electrode plate composed of the formed negative electrode active material layer 7 is accommodated. Leads are formed on each of the current collectors, and are led out of the opening of the battery case 1 via the resin 2 while being insulated from each other.
• Aluminum is preferably used as the positive electrode current collector 3, and copper is preferably used as the negative electrode current collector 6.
• a lithium-containing composite oxide is used as the positive electrode material contained in the positive electrode active material layer 4. Further, among the lithium-containing composite oxides, a lithium-cobalt composite oxide is preferably used.
• a negative electrode material included in the negative electrode active material layer 7 a carbon material, an alloy, an oxide, a nitride, or the like that can insert and remove lithium ions is used. Of these, spheroidal graphite is preferably used.
• silicon dioxide fine particles are used as the inorganic filter included in the separation layer 5.
• both the layer 7 and the separation layer 5 contain a polymer electrolyte.
• a polymer electrolyte There are no particular restrictions on the type of polymer material constituting the polymer electrolyte.
• Examples of the polymer containing at least one acrylate unit and a methyl acrylate unit and an alkylene oxide unit include, for example, polyethylene oxide, polypropylene oxide, or a block copolymer thereof as a main chain, And polymers having an acrylate group or a methacrylate group.
• Examples of the polyurethane having a carbonate group include a reaction product of a polyol having a carbonate group and an aliphatic disocyanate.
• Examples of the polymer containing a vinylidene fluoride unit include a copolymer of vinylidene fluoride and hexafluoropropylene.
• an electrode plate group including a positive electrode plate, a negative electrode plate, and a separator layer containing dimethacrylate having a polyalkylene oxide as a main chain as a polymer material
• the average molecular weight is from 800 to 200, preferably from 100 to
• Dimethacrylate having a polyalkylene oxide as a main chain is dissolved in N-methyl-2-pyrrolidone (hereinafter referred to as NMP) to form a solution.
• NMP N-methyl-2-pyrrolidone
• a lithium cobalt composite oxide as a positive electrode material and acetylene black as a conductive agent are dispersed to form a positive electrode paste.
• a thermal polymerization initiator is added to the positive electrode paste.
• the thermal polymerization initiator As the thermal polymerization initiator,
• AIBN 2, 2'-azobisisobutyronitrile
• spherical graphite as a negative electrode material is dispersed in an NMP solution of dimethacrylate having a polyalkylene oxide as a main chain to prepare a negative electrode paste.
• a thermal polymerization initiator is added to the negative electrode paste as described above. This paste is applied to both surfaces of a copper foil, for example, and heated to polymerize the dimethacrylate and remove NMP. Then, the obtained electrode plate is cut into a predetermined size to obtain a negative electrode plate.
• a liquid non-aqueous electrolyte composed of a non-aqueous solvent and a solute is contained in each electrode plate by vacuum impregnation.
• the non-aqueous solvent include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, getyl carbonate, and ethyl methyl carbonate. It is preferable to use a mixture of two or more of these.
• the solute for example, L i PF 6, L i BF 4 is used.
• a paste for a separator layer is applied on a positive electrode plate containing a nonaqueous electrolyte.
• a paste for a separator layer include dimethacrylate having a polyalkylene oxide as a main chain, a nonaqueous solvent and a solute.
• a mixture comprising a liquid nonaqueous electrolyte, hydrophobic silicon dioxide fine particles, and about 1% by weight of a thermal polymerization initiator based on the weight of the dimethacrylate is used.
• the paste on the positive electrode plate is gelled by heating to form a separator layer.
• the negative electrode plate is sandwiched between the positive electrode plates with the separator layer inside, whereby an electrode group is obtained.
• a lithium polymer primary battery By inserting the obtained electrode plate group into the battery case and sealing the opening of the case, a lithium polymer primary battery can be obtained.
• a paste for the separator layer was also applied thinly on the surface of the negative electrode plate, and the electrode group was housed in the battery case before heating. You may do it.
• the present invention is applicable to all batteries including a polymer electrolyte.
• the present invention can be applied to a battery using a foldable or wound type electrode plate group.
• Lithium cobalt composite oxide as a cathode active material (L i C ⁇ 0 2) , spherical graphite used as a negative electrode active material to prepare a flat lithium poly Ma twelve batteries as shown in FIG.
• the positive electrode was manufactured as follows.
• the dimethacrylate having a polyalkylene oxide as a main chain has the general formula:
• AIBN was added to the positive electrode paste in an amount of 0.5% by weight based on the weight of the dimethacrylate. Apply this paste to one side of the aluminum foil And heated at 80 ° C. to polymerize dimethacrylate and remove the solvent to obtain a positive electrode plate.
• the negative electrode was manufactured as follows.
• the spherical graphite powder was dispersed in an NMP solution containing a predetermined concentration of dimethacrylate having the above-mentioned polyalkylene oxide as a main chain to obtain a negative electrode paste.
• To the negative electrode paste was added 0.5% by weight of IBN based on the weight of the dimethacrylate. This paste was applied on both sides of a copper foil, and heated at 80 ° C. to polymerize dimethacrylate and remove the solvent, thereby obtaining a negative electrode plate.
• Leads were joined to the positive electrode plate and the negative electrode plate, respectively.
• a volume ratio of 1 ethylene carbonate and Jefferies chill carbonate A mixed solvent containing 3, a L i PF 6 as a solute 1 to 5 mol / dm 3 by dissolve, to obtain a non-aqueous electrolyte. Then, the nonaqueous electrolyte was included in the positive electrode plate and the negative electrode plate by vacuum impregnation.
• Separation layer paste is prepared by dissolving dimethacrylate having the above-mentioned polyalkylene oxide as a main chain in the above-mentioned non-aqueous electrolyte at a predetermined concentration. 1% by weight of IBN based on the weight of the dimethacrylate is added. It was prepared by addition.
• a predetermined amount of separation paste was applied to one surface of the positive electrode plate containing a non-aqueous electrolyte, and the paste on the positive electrode plate was gelled by heating to form a separation layer. Then, a separator layer paste was thinly applied to both surfaces of the negative electrode plate containing the electrolyte, and the negative electrode plate was sandwiched between the positive electrode plates with the separator layer inside, to obtain an electrode plate group.
• the electrode group was inserted into a battery case of a laminated film in which aluminum foil was disposed between resin films, and the opening was sealed with resin. Then, in order to strengthen the bonding between the negative electrode and the separation layer, the battery was heated at 100X :.
• the weight ratio of the dimethacrylate obtained from the composition and weight of the solids in the positive electrode plate, the negative electrode plate and the separation layer of this battery was 40% by weight in the positive electrode, 35% by weight in the negative electrode, and 40% by weight in the negative electrode. 25% by weight in the layer.
• the negative electrode paste contained dimethacrylate having a polyalkylene oxide as a main chain and trimethacrylate having a polyalkylene oxide as a main chain at a weight ratio of 3: 1.
• a lithium polymer secondary battery was produced in the same manner as in Example 1, except that the weight ratio of methacrylate in the composition was changed.
• the weight ratio of methacrylate was 50% by weight in the positive electrode, 30% by weight in the negative electrode, and 20% by weight in the separation layer.
• trimethacrylate having a polyalkylene oxide as a main chain has the general formula:
• a battery was fabricated in the same manner as in Example 1, except that the weight ratio of dimethacrylate in each battery component was changed.
• the weight ratio of dimethacrylate was 42% by weight in the positive electrode, 37% by weight in the negative electrode, and 21% by weight in the separation layer.
• a battery was fabricated in the same manner as in Example 1, except that the weight ratio of dimethacrylate in each battery component was changed.
• the weight ratio of dimethacrylate was 45% by weight in the positive electrode, 30% by weight in the negative electrode, and 25% by weight in the separation layer.
• a battery was fabricated in the same manner as in Example 1, except that the weight ratio of dimethacrylate in each battery component was changed.
• the weight ratio of the dimethacrylate acrylate was 37% by weight in the positive electrode, 35% by weight in the negative electrode, and 28% by weight in the separation layer.
• Example 1 Example 1 was repeated except that the dimethacrylate having a polyalkylene oxide as a main chain was replaced with a urethane polymer which was a reaction product of a predetermined force diol and hexamethylene diisocyanate.
• a battery was fabricated in almost the same manner as described above.
• the weight ratio of the urethane polymer was 40% by weight in the positive electrode, 35% by weight in the negative electrode, and 25% by weight in the separation layer.
• the carbonic acid diol has the general formula:
• the one having an average molecular weight of 1,000 was used.
• the carbonate diol and hexamethylene disodium salt contained in the positive electrode paste, the negative electrode paste, and the paste for the separator layer were heated to 80 to 100 ° C. in predetermined steps, respectively. Reacts to form urethane bonds. As a result, urethane with a crosslinked structure Polymer is formed. In this case, no polymerization initiator is required.
• a battery was fabricated in substantially the same manner as in Example 1, except that dimethacrylate having a polyalkylene oxide as a main chain was replaced with a copolymer of vinylidene fluoride and hexafluoropropylene. In this case, no polymerization initiator is required.
• DBP dibutyl phthalate
• An appropriate amount of DBP is 100 to 500 parts by weight per 100 parts by weight of the copolymer of vinylidene fluoride and hexafluoropropylene.
• the paste for the Separe overnight layer was coated on a polyethylene terephthalate film, dried and cut to form a separate evening layer. Then, the negative electrode plate was sandwiched between the obtained separators, and joined by pressing while heating. Next, a negative electrode plate having separators disposed on both sides thereof was sandwiched between positive electrode plates, and pressed while heating to obtain an electrode plate group. Next, DBP contained in the electrode plate group was extracted with dimethyl ether, dried, and inserted into the battery case. Then, a nonaqueous electrolyte was injected into the battery case under vacuum, and the opening of the case was sealed to complete the battery.
• the non-aqueous electrolyte used here was dissolved in a mixed solvent containing ethylene carbonate and ethyl methyl carbonate at a volume ratio of 1: 3 as a solute.
• the L i PF 6 was prepared by dissolving in l. 5 mol Z dm 3.
• the weight ratio of the copolymer of vinylidene fluoride and hexafluoropropylene in the battery was 43% by weight in the positive electrode, 36% by weight in the negative electrode, and 21% by weight in the separation layer. . Comparative Example 1
• a battery was fabricated in the same manner as in Example 1, except that the weight ratio of dimethacrylate in each battery component was changed.
• the weight ratio of the dimethacrylate acrylate was 15% by weight in the positive electrode, 55% by weight in the negative electrode, and 30% by weight in the Separei overnight layer. Comparative Example 2
• a battery was fabricated in the same manner as in Example 1, except that the weight ratio of dimethacrylate acrylate in each battery component was changed.
• the weight ratio of dimethyl acrylate was 55% by weight in the positive electrode, 15% by weight in the negative electrode, and 30% by weight in the separation layer. Comparative Example 3
• a battery was fabricated in the same manner as in Example 6, except that the weight ratio of the urethane polymer in each battery component was changed.
• the weight ratio of the urethane polymer was 45% by weight in the positive electrode, 40% by weight in the negative electrode, and 15% by weight in the separation layer. Comparative Example 4
• a battery was fabricated in the same manner as in Example 7, except that the weight ratio of the copolymer of pinylidene fluoride and hexafluoropropylene in each battery component was changed.
• the weight ratio of the copolymer of vinylidene fluoride and hexafluoropropylene was 20% by weight in the positive electrode, 25% by weight in the negative electrode, and 55% by weight in the Separee overnight layer.
• the batteries of the examples all showed a capacity retention of 85% or more, regardless of the type of the polymer material. From this, the weight ratio of the polymer material constituting the polymer electrolyte in the battery was increased in the order of positive electrode> negative electrode> separation layer, and the polymer material in the positive electrode, the negative electrode and the separation layer was determined. It can be seen that the cycle stability of the battery is improved by setting the amount of styrene within the range of 20 to 50% by weight. This is probably because the distribution of the polymer electrolyte in the battery was made uniform.
• Li Co 2 was used as the positive electrode material
• spherical graphite was used as the negative electrode material.
• positive electrode materials include
• L i N i ⁇ 2 L i Mn 2 ⁇ 4, L i Mn 0 2, alone and L i V 3 O 8, or in combination can be used.
• the negative electrode material include carbon materials such as natural graphite, artificial graphite, graphitized carbon fiber, alloys or oxides of Si, Sn, Al, B, Ge, P, Pb, and the like.
• the weight ratio of the polymer material in the battery to a predetermined ratio, the localization of the polymer electrolyte in the battery can be suppressed, and the polymer electrolyte can be uniformly distributed. Non-uniform volume change of the electrode during cycling can be suppressed. As a result, a highly reliable lithium polymer secondary battery having excellent cycle stability can be provided.

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