Classifications

• • 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
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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  • 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
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  • 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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  • 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
  • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
  • H01M10/0562—Solid materials
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  • 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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  • 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
  • H01M4/04—Processes of manufacture in general
  • H01M4/0402—Methods of deposition of the material
  • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
• • H—ELECTRICITY
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  • 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
  • H01M4/04—Processes of manufacture in general
  • H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
• • 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
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/139—Processes of manufacture
• • 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
• • H—ELECTRICITY
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  • 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
  • H01M4/623—Binders being polymers fluorinated polymers
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  • 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
  • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
• • H—ELECTRICITY
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  • 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
• • 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
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  • 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
  • H01M50/443—Particulate material
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  • 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
  • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
• • 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
  • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
  • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
• • 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
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/028—Positive electrodes
• • 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

Definitions

• the present disclosure relates to a composition for a secondary battery.
• Fluorine-containing polymers are polymers used in many fields. As monomers for producing such polymers, tetrafluoroethylene, vinylidene fluoride, hexafluoropropylene, etc. are well known. Furthermore, a method for producing 1,2-difluoroethylene is disclosed in Patent Document 1. Furthermore, Non-Patent Document 1 discloses the compound and a polymer using the same.
• the present disclosure aims to provide a composition for a secondary battery using a polymer having a structure derived from 1,2-difluoroethylene.
• the present disclosure provides a composition for a secondary battery containing a fluorine-containing polymer and a solvent
• the composition for a secondary battery is characterized in that the fluorine-containing polymer is a polymer containing a structural unit represented by the following general formula (1).
• the fluorine-containing polymer may further include a structural unit represented by the following general formula (2).
• R 1 is hydrogen, fluorine, a partially or fully fluorinated hydrocarbon group having 5 or less carbon atoms, or an OR 5 group (R 5 group is a partially or fully fluorinated hydrocarbon group having 5 or less carbon atoms)
• R 2 , R 3 , and R 4 are each independently hydrogen or fluorine.
• the structural unit represented by the general formula (2) is preferably at least one structural unit selected from the group consisting of structural units represented by the following general formulas (3) to (8).
• the weight average molecular weight of the fluorine-containing polymer is preferably 50,000 to 5,000,000.
• the proportion of the structural unit represented by the general formula (1) in the fluorine-containing polymer is preferably 0.1 to 100 mol%.
• the solvent is at least one compound selected from the group consisting of ester compounds, ketone compounds, and amide compounds.
• the composition for secondary batteries is preferably used for electrodes of secondary batteries.
• the composition for a secondary battery is preferably used for a positive electrode of a secondary battery.
• the composition for a secondary battery is preferably used for a separator of a secondary battery.
• the present disclosure is a method for forming a layer for a secondary battery, which includes a step of applying a slurry onto a base material and drying it by heating, wherein the slurry contains the composition for a secondary battery. It is also a method for forming layers for secondary batteries.
• the present disclosure also provides an electrode for a secondary battery characterized by having an active material layer containing a polymer and an active material containing a structural unit represented by the following general formula (1).
• the present disclosure also provides a solid electrolyte layer for a secondary battery containing a polymer containing a structural unit represented by the following general formula (1) and a solid electrolyte.
• the present disclosure also provides a separator for secondary batteries containing a polymer containing a structural unit represented by the following general formula (1).
• the present disclosure also provides a secondary battery comprising the above secondary battery electrode and/or the above secondary battery separator.
• composition for secondary batteries of the present disclosure is suitable for use in electrode formation, etc., taking advantage of the fact that a polymer having a structure derived from 1,2-difluoroethylene has excellent solubility in various general-purpose solvents. It is possible.
• the present disclosure is a composition for a secondary battery that is suitably used mainly for forming an electrode, an electrolyte layer, or a separator for a secondary battery.
• a method in which a slurry containing sulfide-based solid electrolyte particles, a binder, and a solvent is applied and dried, and then pressed. .
• a good electrode or electrolyte layer it is important to select the binder and solvent used in combination with the sulfide-based solid electrolyte particles.
• sulfide-based solid electrolyte particles it is necessary to select a solvent that does not react with the sulfide-based solid electrolyte particles, which limits the types of solvents that can be used.
• it is necessary to select a binder that dissolves in the solvent In order to prepare a slurry using such a solvent, it is necessary to select a binder that dissolves in the solvent.
• a binder that has suitable solubility in a solvent.
• most of the known binders have low solubility in solvents. For this reason, it could not be sufficiently dissolved in the slurry containing the sulfide-based solid electrolyte particles, and could not fully exhibit its function as a binder.
• polyvinylidene fluoride which is a relatively inexpensive and widely used polymer
• gelation may occur in the slurry. If the binder gels, a uniform slurry cannot be obtained, and therefore it cannot function as a binder.
• Such gelation is particularly likely to occur in a slurry using a positive electrode active material containing lithium hydroxide.
• Some oxide-based solid electrolytes are sensitive to moisture, and it is assumed that they react with moisture in the air and turn into lithium hydroxide, which becomes an alkaline component that causes gelation. It has been known that gelation occurs, particularly in the production of slurries used in the production of electrode materials, and many attempts have been made to improve this problem.
• a composition for a secondary battery suitable for manufacturing a battery is produced. It's something you get. Further, the composition for a secondary battery of the present disclosure is excellent in dispersibility, stability, gelation property, and solid content improvement property with respect to viscosity. Furthermore, lower resistance on the electrode surface can be expected. Furthermore, since a low boiling point solvent can be used, there are advantages such as lowering the drying temperature and shortening the drying time in the manufacturing process of electrodes and the like.
• the fluorine-containing polymer used in the present disclosure is a polymer having a structure represented by the following general formula (1), and may be a homopolymer or a copolymer.
• This structure is obtained by polymerization using 1,2-difluoroethylene as a monomer.
• 1,2-difluoroethylene is a known compound, its use as a refrigerant has heretofore been mainly studied, and its use as a polymerization monomer has hardly been studied.
• a copolymer of 1,2-difluoroethylene and other monomers can be obtained by a common method. Furthermore, the copolymerization ratio can also be easily changed.
• the above-mentioned fluorine-containing polymer is a polymer consisting only of the structure represented by the above general formula (1), or a copolymer having a structural unit represented by the above general formula (1).
• the above-mentioned fluorine-containing polymer may be any of these. Moreover, a mixture of these in arbitrary proportions may be used.
• the above-mentioned fluorine-containing polymer when used as a copolymerized polymer, it preferably has a structural unit represented by the following general formula (2) in addition to the structural unit represented by the above general formula (1).
• R 1 is hydrogen, fluorine, a partially or fully fluorinated hydrocarbon group having 5 or less carbon atoms, or an OR 5 group (R 5 group is a partially or fully fluorinated hydrocarbon group having 5 or less carbon atoms)
• R 2 , R 3 , and R 4 are each independently hydrogen or fluorine.
• the structural unit represented by the above general formula (2) includes a structure derived from an ethylenic monomer in which at least one hydrogen atom may be substituted with fluorine, and a structure in which at least one hydrogen atom is substituted with fluorine.
• Structural units derived from propylene monomers which may be substituted with fluorine structural units derived from butene monomers which may have at least one hydrogen atom substituted with fluorine
• structural units derived from butene monomers which may have at least one hydrogen atom substituted with fluorine structural units derived from butene monomers which may have at least one hydrogen atom substituted with fluorine.
• Structural units derived from pentene monomers that may be used may be mentioned.
• the fluoropolymer of the present disclosure may contain two or more types of copolymerized structural units.
• structures derived from ethylenic monomers in which at least one hydrogen atom may be substituted with fluorine include vinylidene fluoride, tetrafluoroethylene (TFE), vinyl fluoride, 1,1, Examples include 2-trifluoroethylene.
• Examples of the structural unit derived from a propylene monomer in which at least one hydrogen atom is substituted with fluorine include 1270, 1216, 1252, 1243, 1234, 1225, 1252, and the like.
• Examples of the structural unit derived from a butene monomer in which at least one hydrogen atom may be substituted with fluorine include 1390, 1381, 1372, 1363, 1354, 1345, 1336, 1327, 1318, and the like.
• Examples of pentene monomers in which at least one hydrogen atom may be substituted with fluorine include R600, R600a, nonahydrofluoropentene, 1492, 1483, 1474, 1465, 1456, 1447, 1438, 1429, perfluoropentene. etc. can be mentioned. Please note that these are all Ashley numbers.
• Rf 1 to Rf 6 represent a fluoromethyl group having 1 to 3 fluorines.
• the structural unit represented by general formula (2) is (R 1 to R 3 are selected from H and F, and Rf is a fluorine-containing alkyl group having 1 to 6 carbon atoms.) It may be.
• the structural unit represented by the above general formula (20) is a structural unit derived from a fluorinated vinyl ether compound.
• the above-mentioned fluorinated vinyl ether compound is not particularly limited, and includes perfluoromethyl vinyl ether (PMVE) (general formula (7) below), perfluoroethyl vinyl ether (general formula (8) below), perfluoropropyl vinyl ether (general formula (8) below), and perfluoropropyl vinyl ether (general formula (8) below). 9)) etc.
• the structure represented by the above general formula (3) is a structural unit derived from tetrafluoroethylene
• the structure represented by general formula (4) is a structural unit derived from vinylidene fluoride.
• the structure represented by general formula (5) is a structural unit derived from hexafluoropropylene (HFP)
• the structure represented by general formula (7) is a structural unit derived from perfluoro(methyl vinyl ether).
• the structure represented by general formula (8) is a structural unit derived from perfluoro(ethyl vinyl ether).
• the proportion of the structural unit represented by the above general formula (1) is preferably 0.1 mol% or more and 99.9 mol% or less, 1 mol% or more, It is more preferably 99 mol% or less, and even more preferably 10 mol or more and 99 mol% or less. Note that the composition of the fluorine-containing polymer can be measured using an NMR analyzer.
• the proportion of the structural unit represented by the above general formula (2) is preferably 0.1 mol% or more and 99.9 mol% or less.
• the polymer may be difficult to dissolve in general-purpose solvents.
• the fluoropolymer may have a structural unit derived from a copolymer component other than the structural unit represented by the above general formula (2).
• the copolymerization component is not particularly limited, and examples include chlorotrifluoroethylene, hexafluoroisobutene, ethylene, propylene, and alkyl vinyl ether.
• the amount of copolymer components other than the structural unit represented by the above general formula (2) is not particularly limited, but is more preferably 99.9 mol% or less, and should be 99 mol% or less. is more preferable, and most preferably 97 mol% or less.
• the weight average molecular weight of the fluorine-containing polymer is preferably 50,000 to 5,000,000. Setting it within the above range is preferable in terms of heat decomposition resistance and slurry stability.
• the upper limit is more preferably 3,000,000, and even more preferably 2,000,000.
• the lower limit is more preferably 80,000, and even more preferably 100,000.
• the weight average molecular weight is 120,000 or more.
• the weight average molecular weight in the present disclosure is a value measured by gel permeation chromatography (GPC).
• the fluorine-containing polymer according to the present disclosure has the following general formula (10):
• the compound represented by the above general formula (10) is a known compound, and can be produced, for example, by the method described in Patent Document 1.
• the method for producing the above-mentioned fluoropolymer is not particularly limited, and any general polymerization method such as solution polymerization, emulsion polymerization, suspension polymerization, etc. can be used.
• the solvent, emulsifier, initiator, etc. used in these polymerizations are not particularly limited, and commonly known ones can be used.
• the above fluorine-containing polymer has excellent solubility in solvents.
• the fluorine-containing polymer is dissolved in a solvent and takes the form of a slurry.
• the above-mentioned fluorine-containing polymer has good solubility in general-purpose solvents, and therefore is particularly preferable from the viewpoint of cost.
• general-purpose solvents that can dissolve the fluoropolymer include N-methyl-2-pyrrolidone (NMP), acetone, methyl ethyl ketone, tetrahydrofuran, N,N-dimethylformamide, dimethylacetamide (DMAC), butyl acetate, etc. be able to.
• ester compound examples include those represented by the following general formula (21).
• General formula (21) (In the formula, R 1 and R 2 are independently H, a C 1 to C 10 linear or branched aliphatic group, or a C 6 to C 10 aromatic group.)
• R 1 and R 2 are independently H, a C 1 to C 10 linear or branched aliphatic group, or a C 6 to C 10 aromatic group.
• the aliphatic group include a C 1 to C 10 alkyl group or alkenyl group. Specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group.
• decyl group vinyl group, propenyl group, butenyl group and the like.
• methyl, ethyl, propyl, butyl and the like are preferred.
• aromatic group include a phenyl group and a naphthyl group.
• ester compounds include ethyl butyrate, butyl butyrate, propyl propionate, butyl methacrylate, and ethyl acetate.
• ketone compound examples include those represented by the following general formula (22).
• R 3 and R 4 are independently H, a C 1 to C 10 linear or branched aliphatic group, or a C 6 to C 10 aromatic group.
• aliphatic group a C 1 to C 10 alkyl group is preferred.
• a methyl group or an ethyl group is preferred, and a methyl group is more preferred.
• the aromatic group include a phenyl group and a naphthyl group.
• ketone compound examples include acetone, methyl ethyl ketone, and the like.
• Examples of the amide compound include those represented by the following general formula (23) or general formula (24).
• General formula (23) (In the formula, R 5 is H, a C 1 to C 10 linear or branched aliphatic group, or a C 6 to C 10 aromatic group.)
• R 5 is H, a C 1 to C 10 linear or branched aliphatic group, or a C 6 to C 10 aromatic group.
• the aliphatic group and aromatic group are the same as those explained for R 3 and R 4 above.
• R 6 is H, a C 1 to C 10 linear or branched aliphatic group
• R 7 is H, a C 1 to C 10 linear or branched aliphatic group. or a C 6 to C 10 aromatic group.
• two R 7 's may be the same or different.
• the aliphatic group and aromatic group are the same as those explained for R 3 and R 4 above.
• R 5 to R 7 are preferably each independently H, a methyl group, or an ethyl group.
• amide compound examples include N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, and the like.
• a low polar solvent when using a sulfide-based solid electrolyte, it is preferable to use a low polar solvent. It is preferable to use a low polarity solvent because it is less likely to react with the sulfide-based solid electrolyte particles.
• a low polarity solvent is defined as one having a dielectric constant of less than 20 at a frequency of 100 kHz. More preferably, it is less than 10.
• At least one solvent selected from the group consisting of propyl propionate, butyl methacrylate, ethyl acetate, ethyl butyrate, and butyl butyrate can be more preferably used.
• a mixed solvent using two or more of these may be used.
• the polymer concentration may be set depending on the following uses, but it is 0.5% by mass or more and 90.0% by mass or less. It is preferable that The lower limit of the polymer concentration is more preferably 1.0% by mass, and even more preferably 2.5% by mass. The upper limit of the polymer concentration is more preferably 80.0% by mass, and even more preferably 75.0% by mass. By setting it as this range, a stable composition slurry for secondary batteries can be made.
• the secondary battery composition of the present disclosure preferably has a low moisture value, specifically preferably 1000 ppm or less, more preferably 500 ppm or less, still more preferably 100 ppm or less. Most preferably.
• composition for a secondary battery of the present disclosure can be used both for an electrode of a solid battery and for an electrode of a secondary battery containing an electrolyte. It is also used for solid electrolyte layers in solid batteries. Furthermore, it is also used for separators of secondary batteries. Depending on these uses, the components constituting the electrode etc. may be combined as appropriate.
• an electrode active material and a solid electrolyte are further used, and when the electrode is an electrode for a secondary battery containing an electrolyte, an electrode active material is further used. .
• a conductive aid and other components may be used as necessary.
• the composition for a secondary battery of the present disclosure can be used as a slurry for a positive electrode or a slurry for a negative electrode. Furthermore, it can also be used as a slurry for forming a solid electrolyte layer. Among these, when used as a slurry for electrodes, it further contains active material particles. When used as a slurry for electrodes of solid batteries, it contains active material particles and a solid electrolyte. The active material particles can be a positive electrode active material or a negative electrode active material.
• the composition for a secondary battery of the present disclosure can be more suitably used as a slurry for a positive electrode using a positive electrode active material.
• a positive electrode active material When using the composition for a secondary battery of the present disclosure as a slurry for a positive electrode, a positive electrode active material is blended into the slurry.
• a positive electrode active material known as a positive electrode active material of a secondary battery can be applied.
• the positive electrode active material there are no particular limitations on the positive electrode active material as long as it is capable of electrochemically intercalating and deintercalating lithium ions.
• a substance containing lithium and at least one kind of transition metal is preferable, and examples thereof include a lithium transition metal composite oxide and a lithium-containing transition metal phosphate compound.
• the transition metal of the lithium-transition metal composite oxide is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc.
• specific examples of the lithium-transition metal composite oxide include lithium-cobalt composites such as LiCoO 2 oxides, lithium-nickel composite oxides such as LiNiO 2 , lithium-manganese composite oxides such as LiMnO 2 , LiMn 2 O 4 , Li 2 MnO 3 , and transition metal atoms that are the main components of these lithium transition metal composite oxides. Examples include those in which a part of is replaced with other metals such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, and Si.
• substituted substances include, for example, LiNi 0.5 Mn 0.5 O 2 , LiNi 0.85 Co 0.10 Al 0.05 O 2 , LiNi 0.82 Co 0.15 Al 0.03 O 2 , LiNi 0.80 Co 0.15 Al 0.05 O 2 , LiNi 1/3 Co 1/3 Mn 1/3 O 2 , LiNi 0.80 Co 0.10 Mn 0.10 O 2 , LiMn 1. 8 Al 0.2 O 4 , LiMn 1.5 Ni 0.5 O 4 , Li 4 Ti 5 O 12 and the like.
• a positive electrode active material containing Ni the larger the proportion of Ni, the higher the capacity of the positive electrode active material, so further improvement in battery capacity can be expected.
• the transition metal of the lithium-containing transition metal phosphate compound is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc.
• specific examples of the lithium-containing transition metal phosphate compound include, for example, LiFePO 4 , Iron phosphates such as Li 3 Fe 2 (PO 4 ) 3 and LiFeP 2 O 7 , cobalt phosphates such as LiCoPO 4 , and some of the transition metal atoms that are the main components of these lithium-containing transition metal phosphate compounds. Examples include those substituted with other metals such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, and Si.
• LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , LiNi 0.82 Co 0.15 Al 0.03 O 2 , LiNi 0.80 Co 0.15 Al 0.05 O 2 , LiNi 1/3 Co 1/3 Mn 1/3 O 2 and LiFePO 4 are preferred.
• a cathode active material to which a substance having a composition different from that of the substance constituting the main cathode active material is adhered to the surface of the cathode active material.
• Substances attached to the surface include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, and calcium sulfate.
• sulfates such as aluminum sulfate
• carbonates such as lithium carbonate, calcium carbonate, magnesium carbonate, and the like.
• These surface-adhering substances can be prepared, for example, by dissolving or suspending them in a solvent, adding them to the positive electrode active material and drying them, or by dissolving or suspending a surface-adhering substance precursor in a solvent, adding them to the positive electrode active material by impregnating them, and then heating them. It can be attached to the surface of the positive electrode active material by a reaction method such as a reaction method, a method of adding it to a positive electrode active material precursor and firing it at the same time, and the like.
• the amount of the surface-attached substance is preferably 0.1 ppm, more preferably 1 ppm, and even more preferably 10 ppm as a lower limit, and preferably 20%, more preferably 10%, and even more preferably as an upper limit, based on the mass of the positive electrode active material. is used at 5%.
• Substances attached to the surface can suppress the oxidation reaction of the non-aqueous electrolyte on the surface of the positive electrode active material and improve battery life, but if the amount attached is too small, the effect will not be fully realized. If the amount is too large, the resistance may increase because the ingress and egress of lithium ions is inhibited.
• the shape of the positive electrode active material particles can be conventionally used, such as lumps, polyhedrons, spheres, ellipsoids, plates, needles, columns, etc. Among them, primary particles aggregate to form secondary particles. Preferably, the shape of the secondary particles is spherical or ellipsoidal. Normally, as an electrochemical element is charged and discharged, the active material in the electrode expands and contracts, so the stress tends to cause deterioration such as destruction of the active material and breakage of conductive paths. Therefore, rather than a single-particle active material consisting of only primary particles, it is preferable to use a material in which primary particles are aggregated to form secondary particles in order to alleviate the stress of expansion and contraction and prevent deterioration.
• spherical or elliptic spherical particles are less oriented when forming the electrode than plate-like equiaxed particles, so the expansion and contraction of the electrode during charging and discharging is less, and it is also easier to create the electrode. Also when mixed with a conductive aid at the time of mixing, it is preferable because it is easy to mix uniformly.
• the tap density of the positive electrode active material is usually 1.3 g/cm 3 or more, preferably 1.5 g/cm 3 or more, more preferably 1.6 g/cm 3 or more, and most preferably 1.7 g/cm 3 or more. . If the tap density of the positive electrode active material is below the above lower limit, the amount of dispersion medium required will increase when forming the positive electrode active material layer, and the required amount of conductive agent and binder will also increase, causing the positive electrode to the positive electrode active material layer. The filling rate of the active material is restricted, and the battery capacity may be restricted. By using metal composite oxide powder with high tap density, a high-density positive electrode active material layer can be formed.
• the tapped density of the positive electrode active material is determined by passing the sample through a sieve with an opening of 300 ⁇ m and dropping it into a 20 cm 3 tapping cell to fill the cell volume. ), tapping with a stroke length of 10 mm is performed 1000 times, and the density determined from the volume at that time and the weight of the sample is defined as the tapped density.
• the median diameter d50 of the particles of the positive electrode active material is usually 0.1 ⁇ m or more, preferably 0.5 ⁇ m or more, more preferably 1 ⁇ m. Above, it is most preferably 3 ⁇ m or more, and usually 20 ⁇ m or less, preferably 18 ⁇ m or less, more preferably 16 ⁇ m or less, and most preferably 15 ⁇ m or less. If the lower limit is less than the above, it may not be possible to obtain a high bulk density product, and if the upper limit is exceeded, it will take time for the lithium in the particles to diffuse, resulting in a decrease in battery performance, or in the production of the positive electrode of the battery, i.e. the positive electrode active material.
• the median diameter d50 in the present disclosure is measured by a known laser diffraction/scattering particle size distribution measuring device.
• LA-920 manufactured by HORIBA as a particle size distribution meter
• the measured refractive index is set to 1.24 after 5 minutes of ultrasonic dispersion. It is measured as follows.
• the average primary particle diameter of the positive electrode active material is usually 0.01 ⁇ m or more, preferably 0.05 ⁇ m or more, more preferably 0.08 ⁇ m or more, Most preferably it is 0.1 ⁇ m or more, usually 3 ⁇ m or less, preferably 2 ⁇ m or less, more preferably 1 ⁇ m or less, and most preferably 0.6 ⁇ m or less. If the above upper limit is exceeded, it will be difficult to form spherical secondary particles, which will adversely affect powder filling properties and greatly reduce the specific surface area, increasing the possibility that battery performance such as output characteristics will deteriorate. There are cases.
• the primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph with a magnification of 10,000 times, the longest value of the intercept by the left and right boundaries of the primary particles with respect to the horizontal straight line is determined for any 50 primary particles, and the average value is calculated. It will be done.
• the BET specific surface area of the positive electrode active material is 0.2 m 2 /g or more, preferably 0.3 m 2 /g or more, more preferably 0.4 m 2 /g or more, and 4.0 m 2 /g or less, preferably 2 m 2 /g or more. .5 m 2 /g or less, more preferably 1.5 m 2 /g or less. If the BET specific surface area is smaller than this range, the battery performance tends to deteriorate, and if it is larger, it becomes difficult to increase the tap density, which may easily cause problems in coating properties when forming the positive electrode active material.
• the BET specific surface area is determined by pre-drying the sample at 150°C for 30 minutes under nitrogen flow using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken Co., Ltd.), and then measuring the nitrogen concentration against atmospheric pressure. It is defined as a value measured by a nitrogen adsorption BET one-point method using a gas flow method using a nitrogen-helium mixed gas precisely adjusted so that the relative pressure value is 0.3.
• a method for producing the positive electrode active material a method commonly used for producing inorganic compounds is used.
• various methods can be used to prepare spherical or elliptic spherical active materials.
• a spherical precursor is prepared and collected by dissolving or pulverizing and dispersing it in a solvent, adjusting the pH while stirring, and drying this as necessary .
• a Li source such as LiOH, Li 2 CO 3 , or LiNO 3 is added to this, and the mixture is fired at a high temperature.
• transition metal raw materials such as transition metal nitrates, sulfates, hydroxides, and oxides, Li sources such as LiOH, Li 2 CO 3 , LiNO 3 , and other materials as necessary
• a method of dissolving or pulverizing and dispersing the elemental raw material in a solvent such as water, drying and molding it with a spray dryer, etc. to obtain a spherical or ellipsoidal precursor, and firing this at a high temperature to obtain an active material. etc.
• positive electrode active material may be used alone, or two or more types having different compositions or different powder physical properties may be used in combination in any combination and ratio.
• a negative electrode active material is blended into the slurry.
• a negative electrode active material known as a negative electrode active material of a secondary battery can be applied.
• the negative electrode active material is not particularly limited, and includes, for example, lithium metal, artificial graphite, graphite carbon fiber, resin-sintered carbon, pyrolyzed vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-sintered carbon, Select from polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, carbonaceous materials such as non-graphitizable carbon, silicon-containing compounds such as silicon and silicon alloys, Li 4 Ti 5 O 12 , etc. Examples include any one of these, or a mixture of two or more. Among these, those containing at least a portion of a carbonaceous material and silicon-containing compounds can be particularly preferably used.
• the electrode slurry may further contain a conductive additive, if necessary.
• the conductive additive used in the present disclosure is not particularly limited as long as it can improve the intended conductivity in the electrode, but examples include carbon black such as acetylene black and Ketjen black; multi-walled carbon nanotubes; Carbon fibers such as , single-walled carbon nanotubes, carbon nanofibers, and vapor grown carbon fibers (VGCF); metal powders such as SUS powder and aluminum powder; and the like.
• the conductive aid When using a conductive aid, the conductive aid is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.5% by mass or more in the solid content of the electrode slurry.
• the content is usually 50% by mass or less, preferably 30% by mass or less, and more preferably 15% by mass or less. When the content is lower than this range, conductivity may become insufficient. Conversely, if the content is higher than this range, the battery capacity may decrease.
• the slurry may contain materials other than the above materials.
• the content ratio of the material is preferably 8% by mass or less, more preferably 4% by mass or less, when the volume of the entire slurry is 100% by mass.
• the solid electrolyte used in the composition for a secondary battery of the present disclosure may be a sulfide-based solid electrolyte or an oxide-based solid electrolyte.
• a sulfide-based solid electrolyte when used, it has the advantage of being flexible.
• Examples of the sulfide-based solid electrolyte include a lithium ion conductive inorganic solid electrolyte that satisfies the composition represented by the following formula (1).
• Li a1 M b1 P c1 S d1 A e1 (1)
• M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al and Ge.
• A represents an element selected from I, Br, Cl and F.
• a1 to e1 indicate the composition ratio of each element, and a1:b1:c1:d1:e1 satisfies 1 to 12:0 to 5:1:2 to 12:0 to 10.
• a1 is preferably 1 to 9, more preferably 1.5 to 7.5.
• b1 is preferably 0 to 3, more preferably 0 to 1.
• d1 is preferably 2.5 to 10, more preferably 3.0 to 8.5.
• e1 is preferably 0 to 5, more preferably 0 to 3.
• the sulfide-based solid electrolyte preferably contains lithium.
• Sulfide-based solid electrolytes containing lithium are used in solid-state batteries that use lithium ions as carriers, and are particularly preferred in terms of electrochemical devices having high energy density.
• composition ratio of each element can be controlled by adjusting the blending amount of the raw material compounds when producing the sulfide-based solid electrolyte, as described below.
• the sulfide-based solid electrolyte may be amorphous (glass) or crystallized (glass-ceramic), or only partially crystallized.
• glass glass
• glass-ceramic glass-ceramic
• Li-P-S glass containing Li, P, and S, or Li-P-S glass ceramic containing Li, P, and S can be used.
• Sulfide-based solid electrolytes include, for example, lithium sulfide (Li 2 S), phosphorus sulfide (for example, diphosphorus pentasulfide (P 2 S 5 )), elemental phosphorus, elemental sulfur, sodium sulfide, hydrogen sulfide, lithium halide (for example, LiI , LiBr, LiCl) and a sulfide of the element represented by M (for example, SiS 2 , SnS, GeS 2 ).
• Li 2 S lithium sulfide
• P 2 S 5 diphosphorus pentasulfide
• elemental phosphorus elemental phosphorus
• elemental sulfur for example, elemental sulfur
• sodium sulfide sodium sulfide
• hydrogen sulfide hydrogen sulfide
• lithium halide for example, LiI , LiBr, LiCl
• M for example, SiS 2 , SnS, GeS 2
• Li 2 S-P 2 S 5 -LiCl Li 2 S-P 2 S 5 -H 2 S, Li 2 S-P 2 S 5 -H 2 S-LiCl, Li 2 S-LiI-P 2 S 5 , Li 2 S-LiI-Li 2 OP 2 S 5 , Li 2 S-LiBr-P 2 S 5 , Li 2 S-Li 2 OP 2 S 5 , Li 2 S-Li 3 PO 4 - P 2 S 5 , Li 2 S-P 2 S 5 -P 2 O 5 , Li 2 S-P 2 S 5 -SiS 2 , Li 2 S-P 2 S 5 -SiS 2 -LiCl, Li 2 S-P 2 S 5 -SnS, Li 2 S-P 2 S 5 -Al 2 S 3 , Li 2 S-GeS 2 , Li 2 S-GeS 2 , Li 2 S-GeS 2 , Li 2 S-GeS
• the oxide-based solid electrolyte is preferably a compound that contains an oxygen atom (O), has ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and has electronic insulating properties. .
• O oxygen atom
• D ee represents a halogen atom or a combination of two or more halogen atoms), Li xf Si yf O zf (1 ⁇ xf ⁇ 5, 0 ⁇ yf ⁇ 3, 1 ⁇ zf ⁇ 10), Li xg S yg O zg (1 ⁇ xg ⁇ 3, 0 ⁇ yg ⁇ 2, 1 ⁇ zg ⁇ 10), Li 3 BO 3 -Li 2 SO 4 , Li 2 O-B 2 O 3 -P 2 O 5 , Li 2 O-SiO 2 , Li 6 BaLa 2 Ta 2 O 12 , Li 3 PO (4-3/2w) N w (w ⁇ 1), LISICON (Lithium super ionic Li 3.5 Zn 0.25 GeO 4 with a conductor type crystal structure, La 0.55 Li 0.35 TiO 3 with a perovskite type crystal structure, LiTi 2 with a NASICON (Natrium super ionic conductor) type crystal structure P 3 O 12 , Li 1+xh+yh (Al, Ga
• ceramic materials in which elements are substituted for LLZ are also known.
• Hf (hafnium), Ta (tantalum), W (tungsten), Bi (bismuth), and lanthanide elements for LLZ, at least one of Mg (magnesium) and A (A is at least one element selected from the group consisting of Ca (calcium), Sr (strontium),
• Li, P and O phosphorus compounds containing Li, P and O.
• Li 3 PO 4 lithium phosphate
• LiPON in which part of the oxygen in lithium phosphate is replaced with nitrogen
• LiPOD 1 LiPOD 1
• a 1 ON LiA 1 ON (A 1 is at least one selected from Si, B, Ge, Al, C, Ga, etc.) can also be preferably used.
• the oxide solid electrolyte preferably contains lanthanum.
• Oxide-based solid electrolytes containing lanthanum are particularly preferred in terms of good Li ion conductivity.
• the oxide-based solid electrolyte is preferably a garnet-type ion-conductive oxide. It is preferable to select a material having such a structure in terms of good Li ion conductivity.
• the volume average particle diameter of the solid electrolyte is not particularly limited, it is preferably 0.01 ⁇ m or more, more preferably 0.03 ⁇ m or more.
• the upper limit of the volume average particle diameter is preferably 100 ⁇ m or less, more preferably 50 ⁇ m or less.
• the average particle diameter of the solid electrolyte particles is measured by the following procedure.
• the solid electrolyte particles are diluted to a 1% by mass dispersion in a 20 ml sample bottle using water (or heptane in the case of water-labile substances).
• the diluted dispersed sample is irradiated with 1 kHz ultrasonic waves for 10 minutes, and immediately thereafter used for the test.
• the content of the solid electrolyte in the solid component in the solid electrolyte composition is determined based on the solid component of 100% by mass when considering the reduction of interfacial resistance when used in a solid secondary battery and the maintenance of the reduced interfacial resistance. It is preferably 3% by mass or more, more preferably 4% by mass or more, and particularly preferably 5% by mass or more. From the same viewpoint, the upper limit of the solid electrolyte content is preferably 99% by mass or less, more preferably 90% by mass or less, and particularly preferably 80% by mass or less. Further, in the solid electrolyte layer disposed between the positive electrode and the negative electrode, the content is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.
• the upper limit of the content of the solid electrolyte is preferably 99.9% by mass or less, more preferably 99.8% by mass or less, and preferably 99.7% by mass or less. Particularly preferred.
• the above-mentioned solid electrolytes may be used alone or in combination of two or more.
• the solid content refers to a component that does not disappear by volatilization or evaporation when drying is performed at 170° C. for 6 hours in a nitrogen atmosphere. Typically, it refers to components other than the above-mentioned dispersion medium.
• the content of the solvent is preferably 10% by mass or more and 90% by mass or less. If the content ratio of the solvent is less than 10% by mass, the content ratio of the solvent is too small, and the binder, active material, etc. will not dissolve in the solvent, which will hinder the formation of the layer forming the secondary battery. may occur. On the other hand, if the content ratio of the solvent exceeds 90% by mass, the content ratio of the solvent is too large, and it may become difficult to control the basis weight (coating). When the total mass of the slurry is 100% by mass, the content of the solvent is more preferably 20% by mass or more and 70% by mass or less, and even more preferably 25% by mass or more and 65% by mass or less.
• the slurry contains 0.1 parts by mass or more and 9.5 parts by mass or less of the above-mentioned fluorine-containing polymer as a binder, based on 100 parts by mass of the total solid content in the slurry. If the binder is too small, the adhesion within the electrode layer and the adhesion between the negative electrode layer and the current collector will be poor when used as an electrode, and the electrode may be difficult to handle. If there is too much binder, the resistance of the electrode will increase, and it may become impossible to obtain a solid-state battery with sufficient performance.
• the amount of solid content (electrode active material, solid electrolyte, and binder) relative to the solvent is not particularly limited, but for example, the solid content in the slurry is 30% by mass. It is preferable that the amount is 75% by mass or less. With such a solid content ratio, an electrode or solid electrolyte layer can be manufactured more easily.
• the lower limit of the solid content ratio is more preferably 50% by mass or more, and the upper limit of the solid content ratio is more preferably 70% by mass or less.
• each component is mixed to form a slurry.
• the mixing order of each component is not particularly limited, and each component may be added to a solvent and mixed. However, from the viewpoint of obtaining a slurry in which the binder is dissolved, it is preferable to mix by the following method.
• a binder solution in which the above-mentioned binder is dissolved in the above-mentioned solvent in advance, and then mix it with other materials.
• a slurry using the following procedure.
• (1) Add the above-mentioned binder to a solvent to obtain a binder solution containing the binder.
• a binder solution containing the binder containing the binder.
• (2) In the case of an electrode slurry, add the binder solution obtained in (1), a separately prepared positive electrode active material or negative electrode active material, and a solid electrolyte as necessary to the solvent, and stir By performing the treatment, an "electrode slurry" in which the active material, binder, etc. are dispersed in a solvent is obtained.
• an electrode active material, solid electrolyte, and binder are highly dispersed in the solvent, and an "electrode slurry" of a predetermined viscosity is produced. It can be prepared.
• a conductive additive may be added as necessary.
• step (2) In the case of a slurry for solid electrolyte layer, add the binder solution obtained in (1) and the separately prepared solid electrolyte to the solvent, and perform a dispersion process using a stirrer etc. to form a solid A "slurry for a solid electrolyte layer" in which an electrolyte and a binder are highly dispersed in a solvent is obtained.
• a "slurry for solid electrolyte layer" with a predetermined viscosity is prepared while the solid electrolyte and binder are highly dispersed in the solvent. You can.
• a conductive additive may be added as necessary.
• the mixing ratio of the binder, electrode active material, and/or solid electrolyte may be any mixing ratio that will function appropriately when each layer is formed, and may be a known mixing ratio. can be adopted.
• the above slurry can be used to form an electrode for a secondary battery and/or an electrolyte layer for a solid battery.
• the method for manufacturing electrodes for secondary batteries is not particularly limited, but includes (1) a step of preparing a base material, (2) a step of preparing a slurry, and (3) a step of applying the slurry to a secondary battery. This can be carried out by the process of forming battery electrodes. Below, the above steps (1) to (3) will be explained in order.
• Step (1) Step of preparing a base material The base material used in the present disclosure is not particularly limited as long as it has a flat surface to which a slurry can be applied.
• the base material may be plate-shaped or sheet-shaped. Further, the base material may be prepared in advance or may be a commercially available product.
• the base material used in the present disclosure may be used in a secondary battery after forming an electrode for a secondary battery and/or an electrolyte layer for a solid battery, or it may not be a material for a secondary battery. It's okay.
• Examples of base materials used in secondary batteries include electrode materials such as current collectors, materials for solid electrolyte layers such as solid electrolyte membranes, and the like.
• the secondary battery electrode and/or solid battery electrolyte layer obtained by using the slurry of the present disclosure is used as a base material, and the secondary battery electrode and/or solid battery electrolyte layer is further added thereto. It can also be formed.
• Examples of base materials that are not used as materials for secondary batteries include transfer base materials such as transfer sheets and transfer substrates.
• the secondary battery electrode and/or solid battery electrolyte layer formed on the transfer base material are bonded to the secondary battery electrode and/or solid battery electrolyte layer by thermocompression bonding, etc., and then the transfer base material is bonded to the secondary battery electrode and/or solid battery electrolyte layer. By peeling off, a secondary battery electrode can be formed on the solid electrolyte layer.
• the secondary battery electrode formed on the transfer base material can be bonded to the current collector by thermocompression bonding, etc., and then the transfer base material can be peeled off to form the secondary battery electrode on the electrode current collector. Can form electrodes.
• Step (2) Step of preparing a slurry This step can be performed according to the slurry preparation method described above.
• Step (3) Coating the slurry to form an electrode for a secondary battery or an electrolyte layer for a solid battery
• the slurry is coated on at least one surface of the base material to form a secondary battery electrode or a solid battery electrolyte layer.
• This is a step of forming a battery electrode or a solid battery electrolyte layer.
• the electrode for a secondary battery or the electrolyte layer for a solid battery may be formed only on one side of the base material, or may be formed on both sides of the base material.
• the slurry coating method, drying method, etc. can be selected as appropriate.
• examples of the coating method include a spray method, a screen printing method, a doctor blade method, a bar coating method, a roll coating method, a gravure printing method, a die coating method, and the like.
• examples of the drying method include drying under reduced pressure, drying by heating, drying by heating under reduced pressure, and the like. The specific conditions for drying under reduced pressure and drying by heating are not limited and may be set as appropriate.
• the present disclosure also provides an electrode for a secondary battery characterized by having an active material layer containing a polymer containing a structural unit represented by the general formula (1) and an active material.
• the active material layer When used as an electrode for a solid secondary battery, the active material layer further contains a solid electrolyte.
• the secondary battery electrode may include a current collector and a lead connected to the current collector.
• the thickness of the active material layer used in the present disclosure varies depending on the intended use of the secondary battery, etc., but is preferably 10 to 250 ⁇ m, particularly preferably 20 to 200 ⁇ m, particularly 30 ⁇ m. Most preferably, the thickness is between 150 ⁇ m and 150 ⁇ m.
• the current collector used in the present disclosure is not particularly limited as long as it has the function of collecting current from the active material layer described above.
• Examples of the material for the positive electrode current collector include aluminum, SUS, nickel, iron, titanium, chromium, gold, platinum, zinc, and the like, with aluminum and SUS being preferred.
• the shape of the positive electrode current collector may be, for example, foil, plate, mesh, etc., and among these, foil is preferable.
• the positive electrode for a secondary battery according to the present disclosure has excellent adhesive strength by setting the content of the binder to 0.5 to 10% by mass of the positive electrode for a secondary battery (preferably the electrode active material layer). In addition, a secondary battery using the positive electrode exhibits high output.
• the negative electrode for a secondary battery according to the present disclosure has excellent adhesive strength by setting the content of the binder to 0.5 to 10% by mass of the negative electrode for a secondary battery (preferably the electrode active material layer).
• a sulfide-based solid state battery using the negative electrode exhibits high output.
• the present disclosure also provides a solid electrolyte layer containing a polymer containing a structural unit represented by general formula (1) and a solid electrolyte.
• a solid electrolyte layer containing a polymer containing a structural unit represented by general formula (1) and a solid electrolyte.
• the solid electrolyte to be used the solid electrolyte described above may be used.
• the separator of the present disclosure preferably includes a porous base material and a composite porous membrane formed on the porous base material.
• the composite porous membrane preferably contains the fluorine-containing polymer and at least one type of inorganic particle selected from the group consisting of metal oxide particles and metal hydroxide particles.
• the composite porous membrane further contains organic particles.
• the content of the fluorine-containing polymer is preferably 50% by mass or less in the composite porous membrane. If it exceeds 50% by mass, the porosity in the composite porous membrane may decrease too much and the ion permeation function as a separator may no longer be fulfilled.
• the content of the above-mentioned fluorine-containing polymer should be 1% by mass or more in the composite porous membrane, since adhesion between inorganic particles may become insufficient and the mechanical properties of the composite porous membrane may deteriorate significantly. preferable.
• the content of the fluorine-containing polymer in the composite porous membrane is more preferably 45% by mass or less, even more preferably 40% by mass or less, more preferably 2% by mass or more, even more preferably 3% by mass or more, and 4% by mass or more. It is particularly preferable that
• the composite porous membrane includes at least one type of inorganic particle selected from the group consisting of metal oxide particles and metal hydroxide particles.
• the content of the inorganic particles is preferably 50 to 99% by mass in the composite porous membrane.
• the content of the inorganic particles is within the above range, it is possible to obtain a separator in which composite porous membranes having a pore size and porosity that do not impede permeation of lithium ions are laminated. Furthermore, a separator with high heat resistance and less shrinkage due to heat can be realized.
• the content of the inorganic particles in the composite porous membrane is more preferably 55% by mass or more, still more preferably 60% by mass or more, more preferably 98% by mass or less, even more preferably 97% by mass or less, and 96% by mass or less. Particularly preferred.
• the average particle diameter of the inorganic particles is preferably 20 ⁇ m or less, more preferably 10 ⁇ m or less, and even more preferably 5 ⁇ m or less.
• the lower limit of the average particle diameter is preferably 0.001 ⁇ m.
• the above average particle diameter is a value obtained by measurement using a transmission electron microscope, a laser particle size distribution analyzer, or the like.
• the metal oxide particles are preferably metal oxides other than alkali metals or alkaline earth metals from the viewpoint of improving the ionic conductivity and shutdown effect of the separator, such as aluminum oxide, silicon oxide, titanium oxide, vanadium oxide, and copper oxide. At least one selected from the group consisting of is more preferred.
• the average particle diameter of the metal oxide particles is preferably 20 ⁇ m or less, more preferably 10 ⁇ m or less, and even more preferably 5 ⁇ m or less.
• the lower limit of the average particle diameter is preferably 0.001 ⁇ m.
• the above average particle diameter is a value obtained by measurement using a transmission electron microscope.
• Particularly preferable metal oxide particles are aluminum oxide particles or silicon oxide particles having an average particle diameter of 5 ⁇ m or less because of their excellent ionic conductivity.
• the content of the metal oxide particles is preferably 50 to 99% by mass in the composite porous membrane.
• the content of the metal oxide particles is more preferably 55% by mass or more, still more preferably 60% by mass or more, more preferably 98% by mass or less, even more preferably 97% by mass or less, and 96% by mass. The following are particularly preferred.
• the metal hydroxide particles are preferably alkali metal or alkaline earth metal hydroxides, such as magnesium hydroxide, calcium hydroxide, aluminum hydroxide, water At least one selected from the group consisting of chromium oxide, zirconium hydroxide, and nickel hydroxide is more preferred.
• the average particle diameter of the metal hydroxide particles is preferably 20 ⁇ m or less, more preferably 10 ⁇ m or less, and even more preferably 5 ⁇ m or less.
• the lower limit of the average particle diameter is preferably 0.001 ⁇ m.
• the above average particle diameter is a value obtained by measurement using a transmission electron microscope.
• the content of the metal hydroxide particles in the composite porous membrane is preferably 50 to 99% by mass.
• the content of the metal hydroxide particles in the composite porous membrane is more preferably 55% by mass or more, still more preferably 60% by mass or more, more preferably 98% by mass or less, and even more preferably 97% by mass or less.
• the composite porous membrane further contains organic particles.
• the organic particles are preferably nonconductive crosslinked polymers, and more preferably crosslinked polystyrene, crosslinked polymethacrylate, and crosslinked acrylate.
• the average particle diameter of the organic particles is preferably 20 ⁇ m or less, more preferably 10 ⁇ m or less, and even more preferably 5 ⁇ m or less.
• the lower limit of the average particle diameter is preferably 0.001 ⁇ m.
• the above average particle diameter is a value obtained by measurement using a transmission electron microscope.
• the content of the organic particles is preferably 0 to 49% by mass in the composite porous membrane.
• the content of the organic particles is more preferably 2% by mass or more, still more preferably 5% by mass or more, more preferably 37% by mass or less, and even more preferably 35% by mass or less.
• the composite porous membrane may further contain other components in addition to the fluorine-containing polymer, inorganic particles, and organic particles described above.
• other components include other resins and rubber.
• Preferred resins used in combination include, for example, one or more of polyacrylate, polymethacrylate, polyacrylonitrile, polyamideimide, polyvinylidene fluoride (PVdF), and VdF/HEP copolymer resin.
• Preferred rubbers to be used in combination include, for example, one or more of VdF/HFP copolymer rubber, VdF/TFE/HFP copolymer rubber, acrylic rubber, and the like. These rubbers may be crosslinked or non-crosslinked.
• Particularly preferable resins or rubbers used in combination are acrylic rubber from the viewpoint of improving ionic conductivity, and VdF/HFP copolymer rubber from the viewpoint of improving ionic conductivity and oxidation resistance.
• acrylic rubber from the viewpoint of improving ionic conductivity
• VdF/HFP copolymer rubber from the viewpoint of improving ionic conductivity and oxidation resistance.
• examples include VdF/TFE/HFP copolymer rubber and VdF/HFP resin.
• the VdF/HFP copolymer rubber preferably has a VdF unit/HFP unit molar ratio of 80/20 to 65/35.
• the VdF/TFE/HFP copolymer rubber preferably has a VdF unit/HFP unit/TFE unit molar ratio of 80/5/15 to 60/30/10.
• the VdF/HFP resin preferably has a VdF unit/HFP unit molar ratio of 98/2 to 85/15.
• the VdF/HFP resin preferably has a melting point of 100 to 200°C.
• the amount of the other resin or rubber to be blended is preferably 400 parts by mass or less, more preferably 200 parts by mass or less, still more preferably 150 parts by mass or less, based on 100 parts by mass of the fluoropolymer.
• the lower limit varies depending on the desired effect, but is approximately 10 parts by mass.
• the composite porous membrane is preferably provided on a porous base material, and more preferably directly on the porous base material. Further, the composite porous membrane may be provided only on one side of the porous substrate, or may be provided on both sides. Further, the composite porous membrane may be provided so as to cover the entire porous substrate on which the composite porous membrane is provided, or may be provided so as to cover only a part of the porous substrate.
• the weight of the composite porous membrane is preferably in the range of 0.5 to 50.0 g/m 2 when the composite porous membrane is formed only on one side of the porous substrate. If it is less than 0.5 g/m 2 , adhesion to the electrode may not be sufficient. Moreover, if the amount is more than 50.0 g/m 2 , it is not preferable because it causes ion conduction and tends to deteriorate the load characteristics of the battery.
• the weight of the fluorine-containing polymer is preferably 0.1 to 6.0 g/m 2 .
• the above-mentioned porous base material means a base material having pores or voids inside.
• a base material may be a microporous membrane, a porous sheet made of a fibrous material such as a nonwoven fabric, or a striped sheet, or a microporous membrane or porous sheet laminated with one or more other porous layers.
• Examples include composite porous membranes with A microporous membrane is a membrane that has many micropores inside and has a structure in which these micropores are connected, allowing gas or liquid to pass through from one surface to the other. means.
• the material constituting the porous base material can be either an organic material or an inorganic material having electrical insulation properties.
• a thermoplastic resin as the constituent material of the base material.
• the shutdown function is a function that prevents thermal runaway of the battery by dissolving the thermoplastic resin and blocking the pores of the porous base material when the battery temperature rises, thereby blocking the movement of ions.
• the thermoplastic resin a thermoplastic resin having a melting point of less than 200° C. is suitable, and polyolefin is particularly preferred.
• a microporous polyolefin membrane As the porous base material using polyolefin, a microporous polyolefin membrane is suitable.
• a polyolefin microporous membrane As the polyolefin microporous membrane, a polyolefin microporous membrane that has sufficient mechanical properties and ion permeability and is used in conventional separators for non-aqueous secondary batteries can be used. And it is preferable that the polyolefin microporous membrane contains polyethylene from the viewpoint of having the above-mentioned shutdown function.
• the weight average molecular weight of the polyolefin is preferably from 100,000 to 5,000,000. If the weight average molecular weight is less than 100,000, it may be difficult to ensure sufficient mechanical properties. Furthermore, if the weight average molecular weight is greater than 5 million, the shutdown characteristics may deteriorate or molding may become difficult.
• Such a polyolefin microporous membrane can be produced, for example, by the following method. Specifically, (i) a step of extruding the molten polyolefin resin through a T-die to form a sheet, (ii) a step of subjecting the sheet to crystallization treatment, (iii) a step of stretching the sheet, and (iv) a step of heat-treating the sheet.
• a method of forming a microporous membrane by sequentially performing the following steps is mentioned.
• a step of melting a polyolefin resin together with a plasticizer such as liquid paraffin extruding it through a T-die, cooling it and forming it into a sheet
• a step of stretching the sheet examples include a method in which a microporous membrane is formed by sequentially performing a step of extracting a plasticizer from a sheet and (iv) a step of heat-treating the sheet.
• Porous sheets made of fibrous materials include polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, heat-resistant polymers such as aromatic polyamides, polyimides, polyethersulfones, polysulfones, polyetherketones, and polyetherimides.
• a porous sheet made of a fibrous material or a mixture of these fibrous materials can be used.
• the porous base material may be a composite porous base material further laminated with a functional layer.
• the above-mentioned composite porous base material is preferable in that further functions can be added by the functional layer.
• the functional layer for example, from the viewpoint of imparting heat resistance, a porous layer made of a heat-resistant resin or a porous layer made of a heat-resistant resin and an inorganic filler can be used.
• the heat-resistant resin include one or more heat-resistant polymers selected from aromatic polyamide, polyimide, polyethersulfone, polysulfone, polyetherketone, and polyetherimide.
• the inorganic filler metal oxides such as alumina, metal hydroxides such as magnesium hydroxide, etc. can be suitably used.
• the composite method include a method of coating a porous sheet with a functional layer, a method of bonding with an adhesive, a method of thermocompression bonding, and the like.
• the porous base material in the present disclosure is preferably made of at least one resin selected from the group consisting of polyethylene, polypropylene, polyimide, polyamide, polyethylene terephthalate, polyester, and polyacetal among those mentioned above.
• the thickness of the porous base material is preferably in the range of 5 to 50 ⁇ m from the viewpoint of obtaining good mechanical properties and internal resistance.
• the separator of the present disclosure can be manufactured by laminating the composite porous membrane on the porous base material.
• the lamination method is not particularly limited, and any conventionally known method may be employed. Specifically, a method of roll coating a porous substrate with a solution or dispersion obtained by dissolving or dispersing the above fluorine-containing polymer, inorganic particles, and other components as necessary in a solvent or water, and a method of roll coating the above solution. Alternatively, a method of dipping a porous base material in a dispersion liquid, or a method of coating a porous base material with the above solution or dispersion liquid and further immersing the porous base material in an appropriate coagulating liquid is preferable.
• a film made of the composite porous membrane described above may be prepared in advance, and the film and the porous base material may be laminated together by a method such as lamination.
• a method for producing a film made of the above composite porous membrane a solution or dispersion in which the above fluorine-containing polymer, the above inorganic particles, and other components as necessary are dissolved or dispersed in a solvent is mixed into a polyester film, an aluminum film, etc.
• An example of this method is to cast it onto a film with a smooth surface and then peel it off.
• Suitable examples of the solvent include amide solvents such as dimethylacetamide (DMAC); ketone solvents such as acetone; and cyclic ether solvents such as tetrahydrofuran. Further, the above-mentioned fluoropolymer and other components blended as necessary may be used after being dispersed in water.
• amide solvents such as dimethylacetamide (DMAC); ketone solvents such as acetone; and cyclic ether solvents such as tetrahydrofuran.
• the solution or dispersion containing the fluorine-containing polymer and inorganic particles is aqueous, it may be prepared by adding a thickener (stabilizer) for adjusting the viscosity.
• a thickener stabilizer
• examples of the thickener (stabilizer) include carboxyalkylcellulose, alkylcellulose, and hydroxyalkylcellulose.
• a slurry coating solution containing the fluorine-containing polymer, the inorganic particles, water, etc. is coated on the porous substrate by a known method. A method of drying is preferred.
• the slurry-like coating liquid may contain the above-mentioned organic particles, thickener, and the like.
• the slurry-like coating liquid preferably contains the fluorine-containing polymer in an amount of 0.5 to 25% by mass, more preferably 1% by mass or more, and more preferably 20% by mass or less.
• concentration of the fluoropolymer can be adjusted depending on the blending ratio of the fluoropolymer, inorganic particles, and water.
• the slurry-like coating liquid preferably contains 1 to 60% by mass of the inorganic particles, more preferably 2% by mass or more, and more preferably 55% by mass or less.
• concentration of the inorganic particles can be adjusted depending on the blending ratio of the fluoropolymer, inorganic particles, and water.
• the content is preferably from 1 to 60% by mass, more preferably 2% by mass or more, and more preferably 55% by mass or less.
• the concentration of the organic particles can be adjusted depending on the blending ratio of the fluoropolymer, inorganic particles, and water.
• the slurry-like coating liquid contains a thickener
• it is preferably contained in an amount of 0.1 to 20% by mass.
• concentration of the thickener can be adjusted depending on the amount of the thickener added to the slurry coating liquid.
• the present disclosure also provides a secondary battery comprising the above-described secondary battery electrode and/or secondary battery separator.
• the secondary battery is a lithium ion battery.
• a secondary solid battery is a solid battery comprising a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode, the positive electrode and/or the negative electrode containing the above-mentioned fluorine-containing polymer.
• a secondary solid battery is a solid battery comprising a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode, the positive electrode and/or the negative electrode containing the above-mentioned fluorine-containing polymer.
• the positive electrode and negative electrode used in the secondary battery of the present disclosure are the same as the secondary battery electrodes described above.
• the solid electrolyte layer, separator, and battery case that are suitably used in the secondary battery of the present disclosure will be described in detail.
• the solid electrolyte layer used in the secondary battery of the present disclosure is not particularly limited, and preferably contains the solid electrolyte described above.
• the solid electrolyte layer of the present disclosure described above may be used.
• the solid electrolyte layer used in the secondary battery of the present disclosure is preferably a layer made of a sulfide-based solid electrolyte.
• the secondary battery of the present disclosure may include a separator between the positive electrode and the negative electrode.
• the separator include the separator of the present disclosure described above, a porous film made of polyethylene, polypropylene, etc., a nonwoven fabric made of a resin such as polypropylene, a nonwoven fabric such as a glass fiber nonwoven fabric, and the like.
• the secondary battery of the present disclosure may further include a battery case.
• the shape of the battery case used in the present disclosure is not particularly limited as long as it can accommodate the above-mentioned positive electrode, negative electrode, electrolyte layer, etc., but specifically, it can be cylindrical, square, or coin-shaped. , laminate type, etc. Note that the shapes and configurations of the positive electrode, negative electrode, and separator may be changed depending on the shape of each battery.
• a method for manufacturing a solid battery includes a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode, the method comprising: preparing the solid electrolyte layer; or a step of preparing a slurry by kneading a negative electrode active material, a solid electrolyte, a binder, and a solvent or dispersion medium, and forming a positive electrode by coating the slurry on one surface of the solid electrolyte layer,
• there is a method including a step of forming the negative electrode on the other surface of the solid electrolyte layer to produce a solid battery.
• the 1,2-difluoroethylene E used in each of the following examples had a purity of 99.9% by mass or more. The purity was determined to be 99.9% by mass after confirming that no impurity peaks appeared by GC/MS. In addition, a highly pure monomer was obtained by manufacturing according to the example of Patent Document 1 and separating by preparative gas chromatography.
• Polymerization method Polymers were polymerized using the polymerization method in accordance with each of the following synthesis examples. The obtained polymer was evaluated based on the following evaluation criteria.
• DMAC dimethylacetamide solubility
• the copolymer composition was measured by solution NMR method or melt NMR method.
• melting point It can be measured using a differential scanning calorimeter in accordance with ASTM D4591. Specifically, the heat of the copolymer was measured using a differential scanning calorimeter RDC220 (manufactured by Seiko Instruments) at a heating rate of 10° C./min, and the maximum value in the obtained heat of fusion curve was taken as the melting point. .
• NMC622 LiNi 0.6 Mn 0.2 Co 0.2 O 2 AB: Acetylene black
• Polymer synthesis example 1 After introducing 1,330 g of deionized water and 0.67 g of methyl cellulose into an autoclave with an internal volume of 1.8 liters, the inside of the autoclave was sufficiently purged with vacuum nitrogen. Thereafter, the inside of the autoclave was vacuum degassed, and 250 g of 1,2-difluoroethylene E, 1 ml of methanol, and 2 g of di-n-propyl peroxydicarbonate were added to the autoclave under vacuum for 1.5 hours. After raising the temperature to 45° C. and maintaining the temperature at 45° C. for 3 hours, an additional 4 g of di-n-propyl peroxydicarbonate was introduced. Thereafter, the temperature was maintained at 45°C for 4 hours. The maximum pressure reached during this period was 2.7 MPaG. Thereafter, the pressure was released to return to atmospheric pressure, and the reaction product was washed with water and dried to obtain 198 g of fluororesin powder. The melting point was 198.3°C.
• Polymer synthesis example 2 The interior of a stainless steel autoclave with an internal volume of 1.8 L was sufficiently purged with vacuum nitrogen. After that, the inside of the autoclave was vacuum degassed, and 1000g of HFE-347pc-f, 197g of 1,2-difluoroethylene E, and 128g of vinylidene fluoride (VdF) were introduced into the vacuumed autoclave. , the autoclave was warmed to 25°C. Next, 10.5 g of an 8% di( ⁇ -hydrododecafluoroheptanoyl) peroxide (hereinafter abbreviated as "DHP") perfluorohexane solution was introduced into the autoclave to initiate polymerization.
• DHP di( ⁇ -hydrododecafluoroheptanoyl) peroxide
• the starting pressure was 1.04 MPaG.
• a mixed gas of 1,2-difluoroethylene/VdF 86.0/14.0 (mol%) was flowed, and the temperature inside the autoclave was maintained at 25°C for 6.3 hours, then released.
• the pressure was returned to atmospheric pressure, and the reaction product was washed with water and dried to obtain 86 g of fluororesin powder.
• the resulting resin contained 1,2-difluoroethylene and VdF in a molar percentage ratio of 86.1/13.9.
• the melting point was 197.9°C.
• a mixed gas of 1,2-difluoroethylene/VdF 54.0/46.0 (mol%) was flowed, and the temperature inside the autoclave was maintained at 25°C for 6.2 hours, then released. The pressure was returned to atmospheric pressure, and the reaction product was washed with water and dried to obtain 91 g of fluororesin powder.
• the resulting resin contained 1,2-difluoroethylene and VdF in a molar percentage ratio of 53.3/46.7. The melting point was 180.0°C.
• Polymer synthesis example 4 The interior of a glass-lined stainless steel autoclave with an internal volume of 4.1 L was sufficiently purged with vacuum nitrogen. After that, the inside of the autoclave was vacuum degassed, and 2300g of HFE-347pc-f, 41g of 1,2-difluoroethylene E, and 436g of VdF were introduced into the vacuumed autoclave, and then the autoclave was heated to 25°C. It was heated to Next, 14.0 g of 8% DHP perfluorohexane solution was put into the autoclave to start polymerization. The starting pressure was 1.11 MPaG.
• a mixed gas of 1,2-difluoroethylene/VdF 25.0/75.0 (mol%) was flowed, and the temperature inside the autoclave was maintained at 25°C for 3.3 hours. The pressure was returned to atmospheric pressure, and the reaction product was washed with water and dried to obtain 104 g of fluororesin powder.
• the resulting resin contained 1,2-difluoroethylene and VdF in a molar percentage ratio of 24.2/75.8. The melting point was 161.7°C.
• Polymer synthesis example 5 The interior of a glass-lined stainless steel autoclave with an internal volume of 4.1 L was sufficiently purged with vacuum nitrogen. After that, the inside of the autoclave was vacuum degassed, and 2300 g of HFE-347pc-f, 27 g of 1,2-difluoroethylene E, and 423 g of VdF were introduced into the vacuumed autoclave, and then the autoclave was heated to 25°C. It was heated to Next, 14.0 g of 8% DHP perfluorohexane solution was put into the autoclave to start polymerization. The starting pressure was 1.06 MPaG.
• a mixed gas of 1,2-difluoroethylene/VdF 16.0/84.0 (mol%) was flowed, and the temperature inside the autoclave was maintained at 25°C for 3.4 hours, then released. The pressure was returned to atmospheric pressure, and the reaction product was washed with water and dried to obtain 125 g of fluororesin powder.
• the resulting resin contained 1,2-difluoroethylene and VdF in a molar percentage ratio of 16.5/83.5. The melting point was 162.4°C.
• Polymer synthesis example 6 The inside of an autoclave with an internal volume of 0.5 liters was sufficiently purged with vacuum nitrogen. After that, the inside of the autoclave was vacuum degassed, and 150 g of HFE-347pc-f, 23 g of 1,2-difluoroethylene E, and 4 g of tetrafluoroethylene were introduced into the vacuumed autoclave. Warmed to °C. Next, 2.0 g of 8% DHP perfluorohexane solution was put into the autoclave to start polymerization. The polymerization pressure at the beginning was 0.5 MPaG.
• a mixed gas of 1,2-difluoroethylene E/tetrafluoroethylene 85/15 (mol%) was flowed, and the temperature inside the autoclave was maintained at 28°C for 5 hours and 15 minutes, and then released. The pressure was returned to atmospheric pressure, and the reaction product was washed with water and dried to obtain 12.2 g of fluororesin powder.
• the resulting resin contained 1,2-difluoroethylene E and tetrafluoroethylene in a molar ratio of 85.5/14.5. The melting point was 210.0°C.
• Polymer synthesis example 7 The inside of an autoclave with an internal volume of 0.5 liters was sufficiently purged with vacuum nitrogen. Thereafter, the inside of the autoclave was vacuum degassed, and 150 g of HFE-347pc-f, 6.8 g of 1,2-difluoroethylene E, and 20 g of tetrafluoroethylene were introduced into the vacuumed autoclave. was heated to 28°C. Next, 1.5 g of 8% DHP perfluorohexane solution was put into the autoclave to start polymerization. The polymerization pressure at the beginning was 0.5 MPaG.
• a mixed gas of 1,2-difluoroethylene E/tetrafluoroethylene 42/58 (mol%) was flowed, and the temperature inside the autoclave was maintained at 28°C for 1 hour and 50 minutes, and then released. The pressure was returned to atmospheric pressure, and the reaction product was washed with water and dried to obtain 13.1 g of fluororesin powder.
• the resulting resin contained 1,2-difluoroethylene E and tetrafluoroethylene in a molar ratio of 42.4/57.6. The melting point was 246.5°C.
• Polymer synthesis example 8 A 100 ml stainless steel (SUS) autoclave was charged with 40 g of R-225 and 0.43 g of an 8% DHP perfluoroxane solution, cooled to dry ice temperature, replaced with nitrogen, and then 3.0 g of hexane Fluoropropylene (HFP) and 5.2 g of 1,2-difluoroethylene E form were charged, and the mixture was shaken at 25° C. for 13.0 hours using a shaker. By drying the product, 2.41 g of fluororesin was obtained. The resulting resin contained 1,2-difluoroethylene E and HFP in a molar ratio of 99.2/0.8. The melting point was 188.5 degrees.
• SUS stainless steel
• Polymer synthesis example 9 After introducing 600 g of deionized water and 0.3 g of methylcellulose into an autoclave with an internal volume of 1.8 liters, the inside of the autoclave was sufficiently purged with vacuum nitrogen. Thereafter, the inside of the autoclave was vacuum degassed, and 150 g of perfluorooctacyclobutane, 100 g of HFP, and 64 g of 1,2-difluoroethylene E were introduced into the vacuumed autoclave, and then the autoclave was heated to 35°C. Next, 1.5 g of di-n-propyl peroxycarbonate was put into the autoclave to start polymerization. The polymerization pressure at the beginning was 1.16 MPaG.
• the obtained resin contained 1,2-difluoroethylene E and HFP in a molar ratio of 94.9/5.1.
• the melting point was 151.2 degrees.
• Polymer synthesis example 10 A 100 ml stainless steel (SUS) autoclave was charged with 40 g of R-225 and 0.43 g of an 8% DHP perfluoroxane solution, cooled to dry ice temperature, and replaced with nitrogen. , 3,3,3-tetrafluoropropene (HFO-1234yf) and 9.1 g of 1,2-difluoroethylene E form were charged, and the mixture was shaken at 25° C. for 11.8 hours using a shaker. By drying the product, 1.81 g of fluororesin was obtained. The obtained resin contained 1,2-difluoroethylene E and HFO-1234yf in a molar ratio of 96.5/3.5. The melting point was 205.9°C.
• Polymer synthesis example 11 A 100 ml stainless steel (SUS) autoclave was charged with 40 g of R-225 and 0.43 g of an 8% DHP perfluoroxane solution, cooled to dry ice temperature, and replaced with nitrogen, followed by 20.9 g of HFO. -1234yf, 3.8 g of 1,2-difluoroethylene E was charged, and the mixture was shaken at 25° C. for 13.2 hours using a shaker. By drying the product, 1.23 g of fluororesin was obtained. The resulting resin contained 1,2-difluoroethylene E and HFO-1234yf in a molar ratio of 16.3/83.7. There was no melting point.
• Polymer synthesis example 12 A 100 ml stainless steel (SUS) autoclave was charged with 40 g of R-225 and 0.42 g of an 8% DHP perfluoroxane solution, cooled to dry ice temperature, and replaced with nitrogen, followed by 6.0 g of perfluoroxane. Fluoromethyl vinyl ether (PMVE) and 10.2 g of 1,2-difluoroethylene E form were charged, and the mixture was shaken at 25° C. for 13.2 hours using a shaker. By drying the product, 3.0 g of fluororesin was obtained. The obtained resin contained E-form and PMVE in a molar ratio of 95.3/4.5. The melting point was 173.3 degrees.
• SUS stainless steel
• composition for secondary battery (Preparation of composition for secondary battery) Using the polymers of Synthesis Examples 1 to 12 as the binder, NMC622 as the positive electrode active material, AB as the conductive aid, and DMAC as the solvent, the mass ratio of active material/conductive aid/binder/solvent was 72.8/1.1. /1.1/25 using a stirrer to obtain a mixed solution. The mixed solution was allowed to stand at room temperature, and the slurry stability of the mixed solution was evaluated. The results are shown in Table 1.
• the obtained mixed solution was uniformly applied to one side of a positive electrode current collector (aluminum foil with a thickness of 20 ⁇ m), and after completely volatilizing DMAC, a pressure of 10 t was applied using a roll press machine. By pressing, a positive electrode including a positive electrode material layer and a positive electrode current collector was produced. Table 1 shows the coatability of the positive electrode material layer on the positive electrode current collector. Coatability was evaluated visually according to the following criteria. ⁇ ...I was able to create an electrode with a smooth surface without any problems. ⁇ : The electrode was created, but the surface was rough. ⁇ ...The electrode was created, but some parts were broken.
• composition for secondary batteries of the present disclosure takes advantage of the fact that a polymer having a structure derived from 1,2-difluoroethylene has excellent solubility in various organic solvents, and can be used to form electrodes of secondary batteries, etc. It can be suitably used for.

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