WO2024111334A1 - 二次電池用非水電解質および二次電池 - Google Patents

二次電池用非水電解質および二次電池 Download PDF

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WO2024111334A1
WO2024111334A1 PCT/JP2023/038514 JP2023038514W WO2024111334A1 WO 2024111334 A1 WO2024111334 A1 WO 2024111334A1 JP 2023038514 W JP2023038514 W JP 2023038514W WO 2024111334 A1 WO2024111334 A1 WO 2024111334A1
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group
sulfur
nonaqueous electrolyte
negative electrode
secondary battery
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French (fr)
Japanese (ja)
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淵龍 仲
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Panasonic Energy Co Ltd
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Panasonic Energy Co Ltd
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Priority to CN202380080506.5A priority Critical patent/CN120226185A/zh
Priority to EP23894346.8A priority patent/EP4625585A4/en
Priority to JP2024560026A priority patent/JPWO2024111334A1/ja
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • 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
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • 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

  • This disclosure relates to a non-aqueous electrolyte for a secondary battery and a secondary battery.
  • Patent Document 1 proposes a nonaqueous electrolyte solution containing an unsaturated sultone having a specific structure, a nonaqueous solvent, and an electrolyte, in which the amount of unsaturated sultone added is 0.001 to 10 mass % of the total nonaqueous electrolyte solution.
  • Patent Document 1 reports that the use of unsaturated sultone significantly suppresses the reductive decomposition of the non-aqueous electrolyte during high-temperature storage.
  • the non-aqueous electrolyte contains a sulfur-containing compound
  • corrosion of the battery can progresses rapidly when the secondary battery is overdischarged. It is presumed that in an overdischarged battery, sulfate ions or sulfite ions are generated from the sulfur-containing compound, and these ions corrode the battery can.
  • One aspect of the present disclosure includes a non-aqueous solvent, a salt that dissolves in the non-aqueous solvent, and an additive that dissolves in the non-aqueous solvent, the additive including a cyclic carboxylic acid anhydride and a sulfur-containing compound, the sulfur-containing compound including at least one selected from the group consisting of a hexavalent sulfur compound and a tetravalent sulfur compound, and the cyclic carboxylic acid anhydride is represented by the general formula (1):
  • the hexavalent sulfur compound is represented by the general formula (2):
  • the tetravalent sulfur compound has a structure represented by the general formula (3):
  • the present invention relates to a non-aqueous electrolyte for a secondary battery having a structure represented by the formula: R1 to R4 are each independently a hydrogen atom, a fluorine atom, or a hydrocarbon group; X1 is a fluorine atom, a hydrocarbon group, or an oxyhydrocarbon group; X2, X3, and X4 are each independently a hydrocarbon group, a silyl group, or an alkali metal; at least one hydrogen atom of the hydrocarbon group may be substituted with a halogen atom; X1 and X2 may form a ring; and X3 and X4 may form a ring.
  • a secondary battery comprising a positive electrode, a separator, a negative electrode facing the positive electrode via the separator, a non-aqueous electrolyte, and a battery can housing the positive electrode, the separator, the negative electrode, and the non-aqueous electrolyte, the non-aqueous electrolyte being the non-aqueous electrolyte for secondary batteries described above.
  • the non-aqueous electrolyte contains a sulfur-containing compound, corrosion of the battery can is suppressed when the secondary battery is in an overdischarged state.
  • FIG. 1 is a vertical cross-sectional view of a secondary battery according to an embodiment of the present disclosure.
  • any of the exemplified lower limits and any of the exemplified upper limits can be arbitrarily combined as long as the lower limit is not equal to or greater than the upper limit.
  • one of them may be selected and used alone, or two or more may be used in combination.
  • Non-aqueous electrolyte secondary batteries include lithium ion secondary batteries that use a material that reversibly absorbs and releases at least lithium ions as the negative electrode active material, lithium secondary batteries in which lithium metal precipitates at the negative electrode during charging and dissolves during discharging, and solid-state batteries that contain a gel electrolyte.
  • the nonaqueous electrolyte secondary battery according to the present disclosure comprises a positive electrode, a negative electrode, a nonaqueous electrolyte, and a battery can that contains these.
  • a separator is usually disposed between the positive electrode and the negative electrode.
  • the nonaqueous electrolyte usually has lithium ion conductivity.
  • overdischarge characteristics can be evaluated based on the content of components eluted from the battery can in the non-aqueous electrolyte in a battery that has been overdischarged by shorting the positive and negative electrodes.
  • high-temperature cycle characteristics can be evaluated based on the capacity retention rate when a secondary battery is subjected to constant-current constant-voltage charging (CCCV charging) for a specified number of cycles in a 45°C environment.
  • CCCV charging constant-current constant-voltage charging
  • the non-aqueous electrolyte includes a non-aqueous solvent, a salt, and an additive.
  • the non-aqueous electrolyte including a non-aqueous solvent is usually a liquid electrolyte, but may be in a state in which the fluidity is restricted by a gelling agent or the like.
  • a lithium salt is used as the salt.
  • the salt and the additive are basically dissolved in the non-aqueous solvent, but as long as the effect of the invention is not significantly impaired, a part of the salt or the additive may not dissolve and may precipitate or separate.
  • the additive defined by the general formula described below may be a salt. In that case, another salt is dissolved in the non-aqueous solvent as a supporting electrolyte.
  • the non-aqueous electrolyte recovered from the secondary battery It is not necessary for the non-aqueous electrolyte recovered from the secondary battery to contain almost no additives. In this case, the oxidation or reduction products of the additives are contained as coating components on the positive or negative electrode surface. Even in such cases, the additives usually remain in the non-aqueous electrolyte collected from the secondary battery at levels above the detection limit, so it is possible to confirm that the non-aqueous electrolyte contains the additives.
  • the cyclic carboxylic acid anhydride and the sulfur-containing compound are classified as additives.
  • the sulfur-containing compound includes at least one selected from the group consisting of a hexavalent sulfur compound and a tetravalent sulfur compound.
  • Cyclic carboxylic acid anhydrides are represented by the general formula (1):
  • R1 to R4 are each independently a hydrogen atom, a fluorine atom, or a hydrocarbon group. At least one hydrogen atom of the hydrocarbon group may be substituted with a halogen atom.
  • Hexavalent sulfur compounds have the general formula (2):
  • X1 is a fluorine atom, a hydrocarbon group, or an oxyhydrocarbon group
  • X2 is a hydrocarbon group, a silyl group, or an alkali metal.
  • X1 and X2 may form a ring. That is, the hexavalent sulfur compound may be a cyclic sulfur compound. At least one hydrogen atom of the hydrocarbon group may be substituted with a halogen atom.
  • Tetravalent sulfur compounds have the general formula (3):
  • X3 and X4 are each independently a hydrocarbon group, a silyl group, or an alkali metal. X3 and X4 may form a ring. That is, the tetravalent sulfur compound may be a cyclic sulfur compound. At least one hydrogen atom of the hydrocarbon group may be substituted with a halogen atom.
  • cyclic carboxylic acid anhydride (1) the cyclic carboxylic acid anhydride represented by general formula (1) (hereinafter also referred to as “cyclic carboxylic acid anhydride (1)”) does not have the effect of suppressing corrosion of battery cans by itself.
  • the cycle characteristics are improved. This is believed to be because when cyclic carboxylic anhydride (1) is used in combination with sulfur compound (2) and/or (3), a hybrid coating that is strong and does not inhibit the permeation of lithium ions is formed as a protective coating on both the positive and negative electrodes.
  • the hybrid coating has the effect of reducing the charge transfer resistance of the positive and negative electrodes while highly suppressing side reactions and improving high-temperature cycle characteristics. The effect of reducing the charge transfer resistance significantly reduces the resistance of the secondary battery.
  • the coating components derived from the cyclic carboxylic anhydride (1) and sulfur compounds (2) and (3) that make up the hybrid coating are presumed to have the effect of, for example, inhibiting excessive reaction of the transition metal elements that make up the positive electrode active material contained in the positive electrode with the electrolyte, thereby suppressing deterioration of the positive electrode active material.
  • the positive electrode active material contains a lithium-containing composite oxide that contains a high content of Ni, the effect of suppressing deterioration is remarkable.
  • the coating components derived from the cyclic carboxylic anhydride (1) and the sulfur compounds (2) and (3) that constitute the hybrid coating are presumed to have the effect of suppressing the deterioration of the negative electrode active material (e.g., graphite or silicon-containing material) contained in the negative electrode by suppressing excessive reaction with the electrolyte.
  • the negative electrode active material e.g., graphite or silicon-containing material
  • the effect of suppressing deterioration is particularly noticeable when the negative electrode active material contains a silicon-containing material.
  • R1 to R4 and X1 to X4 are aliphatic hydrocarbon groups or aliphatic oxyhydrocarbon groups (alkoxy groups, etc.), it is desirable that the steric hindrance is small, and for example, a C1-5 hydrocarbon group or oxyhydrocarbon group (alkoxy group, etc.) having 1 to 5 carbon atoms may be used.
  • R1 to R4 and X1 to X4 are aromatic hydrocarbon groups (aryl groups), the number of aromatic rings may be one.
  • the ring may be a 5-membered ring, a 6-membered ring, or a 7-membered ring.
  • the alkali metal may be Li, K, Na, or the like.
  • X1 to X4 form a ring, X1 and X2 or X3 and X4 are united to form, for example, an alkylene group, an alkenylene group, an ether group, or the like.
  • R1 to R4 of the cyclic carboxylic anhydride (1) may all be hydrogen atoms, or one or more may be a fluorine atom and the remainder may be a hydrogen atom. At least one of R1 to R4 may be an alkyl group, an alkenyl group, or an aryl group, and the remainder may be independently a hydrogen atom or a fluorine atom.
  • the alkyl group is preferably one with small steric hindrance, and may be, for example, a C1-5 alkyl group having 1 to 5 carbon atoms.
  • the alkenyl group may be a C2-5 alkenyl group having 2 to 5 carbon atoms.
  • Such a hydrocarbon group may be, for example, a methyl group, an ethyl group, an ethylene group, a propyl group, a propylene group, or the like.
  • one or more hydrogen atoms of the compounds exemplified above may be substituted with a substituent.
  • the substituent include an alkyl group, a hydroxyalkyl group, a hydroxy group, an alkoxy group, and a halogen atom.
  • the number of carbon atoms in the substituent may be 1 to 3.
  • the halogen atom is preferably a fluorine atom.
  • a typical example of a cyclic carboxylic acid anhydride is diglycolic acid anhydride. It is desirable that diglycolic acid anhydride accounts for 50% by mass or more, and even 80% by mass or more, of the cyclic carboxylic acid anhydride (1).
  • the additive may contain an acid anhydride other than the cyclic carboxylic acid anhydride (1) (hereinafter also referred to as "acid anhydride (2)").
  • the amount of the acid anhydride (2) is preferably less than 50 mass% of the total amount of acid anhydrides, and more preferably less than 30 mass%.
  • the acid anhydride (2) include maleic anhydride, succinic anhydride, acetic anhydride, phthalic anhydride, and benzoic anhydride. Among these, maleic anhydride, succinic anhydride, and the like are preferred.
  • X1 in sulfur compound (2) is a fluorine atom
  • X2 is preferably an alkyl group, an alkenyl group, an aryl group, a silyl group, or an alkali metal.
  • X1 and X2 in sulfur compound (2) may be alkylene groups, alkenylene groups, ether groups, etc., forming a ring.
  • Sulfur compound (2) may also contain two hexavalent sulfurs. In that case, X1 may be an ether group shared by two sulfur atoms, and X2 may be an alkylene group shared by two sulfur atoms.
  • X3 and X4 in the sulfur compound (3) may be an alkyl group, an alkenyl group, or an aryl group.
  • X3 and X4 may be an alkylene group, an alkenylene group, an ether group, or the like, forming a ring.
  • the sulfur compound (3) may also contain two tetravalent sulfur atoms. In that case, X3 and X4 may be an alkylene group or an ether group shared by two sulfur atoms.
  • the sulfate ester is preferably a C2-4 alkyl sulfate, specifically, ethylene sulfate, propylene sulfate, trimethylene sulfate, butylene sulfate, vinylene sulfate, ethyl sulfate, methyl sulfate, etc.
  • the sulfite is preferably a C2-4 alkylene sulfite, specifically, ethylene sulfite (ES), propylene sulfite, trimethylene sulfite, butylene sulfite, vinylene sulfite, etc.
  • ES ethylene sulfite
  • propylene sulfite propylene sulfite
  • trimethylene sulfite trimethylene sulfite
  • butylene sulfite vinylene sulfite, etc.
  • the sulfonic acid ester is preferably at least one selected from the group consisting of C 3-5 alkane sultone and C 3-5 alkene sultone, specifically 1,3-propane sultone, 1,4-butane sultone, 1,3-propene sultone, etc.
  • the sulfur-containing compound may have one or more hydrogen atoms of the compounds exemplified above substituted with a substituent.
  • substituents include an alkyl group, a hydroxyalkyl group, a hydroxy group, an alkoxy group, and a halogen atom.
  • the number of carbon atoms in the substituent may be 1 to 3.
  • the halogen atom is preferably a fluorine atom.
  • At least one selected from the group consisting of lithium fluorosulfonate (LiFSO 3 ), 1-propene-1,3-sultone (PRS), ethylene sulfate (DTD), and 1,5,2,4-dioxadithiane-2,2,4,4-tetraoxide (MMDS) is particularly desirable because it is easily available and has a large effect of reducing resistance and improving high-temperature cycle characteristics. It is desirable for one or more of these to account for 50 mass % or more, and further 80 mass % or more, of the hexavalent sulfur compounds.
  • tetravalent sulfur compounds at least one selected from the group consisting of ethylene sulfite (ES) and vinyl ethylene sulfite (VES) is particularly desirable because it is easy to obtain and has a large effect of improving high-temperature cycle characteristics while reducing resistance. It is desirable for one or more of these compounds to account for 50% by mass or more, and even 80% by mass or more, of the tetravalent sulfur compounds.
  • ES ethylene sulfite
  • VES vinyl ethylene sulfite
  • the content of cyclic carboxylic anhydride (1) in the non-aqueous electrolyte is, for example, 2.5% by mass or less, and may be 0.01% by mass to 2.5% by mass, 0.1% by mass to 2.0% by mass, or 0.5% by mass to 1.5% by mass.
  • a hybrid film is formed appropriately, and the charge/discharge reaction is likely to proceed uniformly, which is thought to enhance the effect of suppressing side reactions.
  • cyclic carboxylic anhydride (1) is consumed to form the film. Therefore, it is sufficient that the non-aqueous electrolyte collected from the secondary battery contains cyclic carboxylic anhydride (1) at a concentration equal to or higher than the detection limit.
  • the content of the sulfur-containing compound in the non-aqueous electrolyte is, for example, 5% by mass or less, and may be 0.01% to 5% by mass, 0.01% to 2.5% by mass, 0.1% to 2.0% by mass, or 0.5% to 1.5% by mass.
  • the viscosity of the non-aqueous electrolyte does not increase excessively, a hybrid film is appropriately formed, and the charge/discharge reaction is likely to proceed uniformly, which is thought to enhance the effect of suppressing side reactions.
  • the sulfur-containing compound is consumed to form the film. Therefore, it is sufficient that the non-aqueous electrolyte collected from the secondary battery contains the sulfur-containing compound at a concentration equal to or higher than the detection limit.
  • the non-aqueous electrolyte may contain additives other than those mentioned above.
  • additives include at least one selected from the group consisting of vinylene carbonate, fluoroethylene carbonate, and vinylethylene carbonate.
  • Non-aqueous solvent examples include cyclic carbonates, chain carbonates, cyclic carboxylates, chain carboxylates, cyclic ethers, chain ethers, etc.
  • the non-aqueous electrolyte may contain one type of non-aqueous solvent or a combination of two or more types.
  • Cyclic carbonates include propylene carbonate (PC), ethylene carbonate (EC), fluoroethylene carbonate (FEC), vinylene carbonate (VC), etc.
  • chain carbonate esters examples include diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), etc.
  • Cyclic carboxylate esters include gamma-butyrolactone (GBL) and gamma-valerolactone (GVL).
  • chain carboxylic acid esters examples include methyl formate, ethyl formate, propyl formate, methyl acetate (MA), ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate.
  • Cyclic ethers include 1,3-dioxolane, 4-methyl-1,3-dioxolane, tetrahydrofuran, and 2-methyltetrahydrofuran.
  • chain ethers examples include 1,2-dimethoxyethane, diethyl ether, ethyl vinyl ether, methyl phenyl ether, benzyl ethyl ether, diphenyl ether, dibenzyl ether, 1,2-diethoxyethane, diethylene glycol dimethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.
  • lithium salts are used as salts.
  • LiClO4 , LiBF4 , LiPF6 , LiAlCl4, LiSbF6 , LiSCN, LiCF3SO3 , LiCF3CO2 , LiAsF6 , LiB10Cl10 , lower aliphatic lithium carboxylate, LiCl, LiBr, LiI, phosphates, borates , and imide salts can be mentioned.
  • phosphates include lithium difluorophosphate ( LiPO2F2 ), lithium difluorobis(oxalato)phosphate ( LiDFBOP ), and lithium tetrafluoro(oxalato)phosphate.
  • borates include lithium bis(oxalato)borate (LiBOB), and lithium difluoro(oxalato)borate (LiDFOB).
  • imide salts examples include lithium bisfluorosulfonylimide (LiN( FSO2 ) 2 ), lithium bistrifluoromethanesulfonyl imide (LiN( CF3SO2 ) 2 ), lithium trifluoromethanesulfonyl nonafluorobutanesulfonyl imide (LiN( CF3SO2 )( C4F9SO2 )), lithium bispentafluoroethanesulfonyl imide (LiN(C2F5SO2 ) 2 ) , etc.
  • the nonaqueous electrolyte may contain one type of lithium salt or a combination of two or more types.
  • the concentration of the lithium salt in the non-aqueous electrolyte is, for example, 0.5 mol/L or more and 2 mol/L or less.
  • each component in the non-aqueous electrolyte is determined, for example, by gas chromatography under the following conditions.
  • Measuring device Shimadzu GC-2010 Plus Column: J&W HP-1 (1 ⁇ m x 60 m) Linear velocity: 30.0 cm/sec Inlet temperature: 270°C Detector: FID 290°C (sens. 10 1 )
  • the positive electrode includes a positive electrode current collector and a positive electrode mixture layer provided on the surface of the positive electrode current collector.
  • the positive electrode current collector is made of a sheet-like conductive material.
  • the positive electrode mixture layer is supported on one or both surfaces of the positive electrode current collector.
  • the positive electrode mixture layer is usually a layer or film made of a positive electrode mixture.
  • the thickness of the positive electrode mixture layer is, for example, 10 ⁇ m to 150 ⁇ m per side of the positive electrode current collector.
  • the positive electrode mixture contains a positive electrode active material as an essential component.
  • the positive electrode mixture layer may contain a conductive agent as an optional component.
  • conductive agents include carbon-based materials such as carbon black (CB), acetylene black (AB), ketjen black, carbon nanotubes (CNT), graphene, and graphite. These may be used alone or in combination of two or more types.
  • the positive electrode mixture layer may contain a binder.
  • binders include fluorine-based resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide-based resins, acrylic-based resins, and polyolefin-based resins. These may be used alone or in combination of two or more types.
  • a non-porous conductive substrate such as metal foil
  • a porous conductive substrate such as a mesh, net, or punched sheet
  • examples of materials for the positive electrode current collector include aluminum, aluminum alloys, titanium, and titanium alloys.
  • a lithium-containing composite oxide As the positive electrode active material, a lithium-containing composite oxide can be used.
  • the lithium-containing composite oxide may have a layered rock salt structure.
  • the layered rock salt structure may belong to, for example, space group R-3m, space group C2/m, etc. Among these, a layered rock salt structure belonging to space group R-3m is preferred in terms of high capacity and high stability of the crystal structure.
  • the layered rock salt structure of the lithium-containing composite oxide may include a transition metal layer, a Li layer, and an oxygen layer.
  • the ratio of Ni to the metal elements other than Li contained in the lithium-containing composite oxide may be 50 atomic % or more, 80 atomic % or more, or 90 atomic % or more.
  • the ratio of Co to the metal elements other than Li contained in the lithium-containing composite oxide may be set to 0 atomic % or more and 16 atomic % or less, or 1.5 atomic % or more and 16 atomic % or less.
  • the ratio of Al to the metal elements other than Li contained in the lithium-containing composite oxide may be set to 0 atomic % or more and 18.5 atomic % or less, or 4 atomic % or more and 10 atomic % or less.
  • the ratio of Mn to the metal elements other than Li contained in the lithium-containing composite oxide may be set to 0 atomic % or more and 50 atomic % or less, or 0 atomic % or more and 30 atomic % or less.
  • the content of each metal element contained in the lithium-containing composite oxide is measured, for example, by inductively coupled plasma (ICP) atomic emission spectrometry.
  • ICP inductively coupled plasma
  • the negative electrode may include a negative electrode current collector and a negative electrode mixture layer provided on the surface of the negative electrode current collector.
  • the negative electrode current collector is composed of a sheet-shaped conductive material.
  • the negative electrode mixture layer is supported on one or both surfaces of the negative electrode current collector.
  • the negative electrode mixture layer is usually a layer or film composed of a negative electrode mixture.
  • the thickness of the negative electrode mixture layer is, for example, 10 ⁇ m to 150 ⁇ m per one side of the negative electrode current collector.
  • the negative electrode mixture contains a negative electrode active material as an essential component, and may contain a binder, a conductive agent, a thickener, and the like as optional components. As the binder, the conductive agent, and the thickener, known materials can be used.
  • Negative electrode active materials include materials that electrochemically absorb and release lithium ions, lithium metal, lithium alloys, etc. Examples of materials that electrochemically absorb and release lithium ions include carbon materials and alloy-based materials.
  • carbon materials examples include graphite, easily graphitized carbon (soft carbon), and non-graphitizable carbon (hard carbon).
  • soft carbon easily graphitized carbon
  • hard carbon non-graphitizable carbon
  • graphite is preferred because of its excellent charge/discharge stability and low irreversible capacity.
  • Graphite is a carbonaceous material with a developed graphite crystal structure.
  • the interplanar spacing d002 of the (002) plane of graphite measured by X-ray diffraction may be, for example, 0.340 nm or less, or 0.3354 nm or more and 0.340 nm or less.
  • the crystallite size Lc(002) of graphite may be, for example, 5 nm or more, or 5 nm or more and 200 nm or less.
  • the crystallite size Lc(002) is measured, for example, by the Scherrer method.
  • An alloy-based material is a material that contains at least one metal that can form an alloy with lithium.
  • Such materials include silicon, tin, silicon alloys, tin alloys, silicon oxide, tin oxide, and silicon-containing materials.
  • the silicon-containing material includes, for example, a lithium ion conductive phase and a silicon phase dispersed in the lithium ion conductive phase.
  • the lithium ion conductive phase may be, for example, a silicon oxide phase, a silicate phase, a carbon phase, or the like.
  • the content of the silicon phase dispersed in the lithium ion conductive phase is, for example, 30% by mass or more and 95% by mass or less, and may be 35% by mass or more and 75% by mass or less.
  • the silicon-containing material may be used alone or in combination of two or more types.
  • the main component of the silicon oxide phase may be silicon dioxide.
  • a silicon-containing material including a silicon oxide phase and a silicon phase dispersed in the silicon oxide phase is represented by SiO x , where x is, for example, 0.5 ⁇ x ⁇ 2, and may be 0.8 ⁇ x ⁇ 1.6.
  • the silicon oxide phase may be an amorphous phase.
  • SiO x is obtained, for example, by the disproportionation reaction of silicon monoxide.
  • Silicate phases are preferred because they have a small irreversible capacity.
  • silicate phases containing lithium (hereinafter also referred to as lithium silicate phases) are preferably used as lithium ion conductive phases that have a high initial charge/discharge efficiency.
  • the lithium silicate phase may be an oxide phase containing lithium (Li), silicon (Si), and oxygen (O), and may contain other elements.
  • the atomic ratio of O to Si in the lithium silicate phase: O/Si is, for example, greater than 2 and less than 4.
  • O/Si is greater than 2 and less than 3.
  • the atomic ratio of Li to Si in the lithium silicate phase: Li/Si is, for example, greater than 0 and less than 4.
  • Examples of elements other than Li, Si, and O that may be contained in the lithium silicate phase include iron (Fe), chromium (Cr), nickel (Ni), manganese (Mn), copper (Cu), molybdenum (Mo), zinc (Zn), and aluminum (Al).
  • the carbon phase may be composed of, for example, amorphous carbon with low crystallinity (i.e., amorphous carbon).
  • amorphous carbon may be, for example, hard carbon, soft carbon, or something else.
  • a silicon-containing material in which a silicon phase is dispersed within a carbon phase can be obtained, for example, by pulverizing a mixture of a carbon source and raw silicon while stirring it in a ball mill or the like to form fine particles, and then heat-treating the mixture in an inert atmosphere.
  • a silicon source such as carboxymethylcellulose (CMC) or water-soluble resins such as polyvinylpyrrolidone are used as carbon sources.
  • a silicon-containing material and a carbon material may be used in combination as the negative electrode active material. Since the volume of the silicon-containing material expands and contracts with charging and discharging, if the ratio of the silicon-containing material in the negative electrode active material increases, poor contact between the negative electrode active material and the negative electrode current collector is likely to occur with charging and discharging. On the other hand, by using a silicon-containing material in combination with a carbon material, it is possible to achieve excellent cycle characteristics while imparting a high capacity to the negative electrode.
  • the proportion of the silicon-containing material in the total of the silicon-containing material and the carbon material is, for example, preferably 0.5 to 15 mass%, and more preferably 1 to 10 mass%. This makes it easier to achieve both high capacity and improved cycle characteristics.
  • a non-porous conductive substrate such as metal foil
  • a porous conductive substrate such as a mesh, net, or punched sheet
  • materials for the negative electrode current collector include stainless steel, nickel, nickel alloys, copper, and copper alloys.
  • the composition of the silicon-containing material can be determined, for example, by obtaining a backscattered electron image of the cross section of the negative electrode mixture layer using a field emission scanning electron microscope (FE-SEM), observing the particles of the silicon-containing material, and performing elemental analysis on the observed particles of the silicon-containing material.
  • FE-SEM field emission scanning electron microscope
  • elemental analysis for example, an electron probe micro analyzer (EPMA) analysis is used.
  • the negative electrode mixture layer may contain a binder.
  • binders include fluororesins (e.g., polytetrafluoroethylene, polyvinylidene fluoride), polyolefin resins (e.g., polyethylene, polypropylene), polyamide resins (e.g., aramid resins), polyimide resins (e.g., polyimide, polyamideimide), acrylic resins (e.g., polyacrylic acid, polymethacrylic acid, acrylic acid-methacrylic acid copolymer, ethylene-acrylic acid copolymer, or salts thereof), vinyl resins (e.g., polyvinyl acetate), and rubber-like materials (e.g., styrene-butadiene copolymer rubber (SBR)).
  • fluororesins e.g., polytetrafluoroethylene, polyvinylidene fluoride
  • polyolefin resins e.g., polyethylene, poly
  • the negative electrode mixture layer may contain a thickener.
  • the thickener include cellulose derivatives such as cellulose ether.
  • the cellulose derivatives include CMC and its modified products, methylcellulose, and the like.
  • Modified CMC also includes salts of CMC.
  • the salts include alkali metal salts (e.g., sodium salts) and ammonium salts.
  • the thickener may be used alone or in combination of two or more types.
  • the negative electrode mixture layer may contain a conductive agent.
  • the conductive agent include carbon nanotubes (CNTs) and conductive particles.
  • the conductive particles include conductive carbon (carbon black, etc.) and metal powder.
  • the conductive agent may be used alone or in combination of two or more types.
  • the negative electrode current collector is selected according to the type of non-aqueous electrolyte secondary battery.
  • Examples of the negative electrode current collector include sheet-shaped ones. Metal foils and the like may also be used as the current collector. Porous current collectors may also be used. Examples of porous current collectors include mesh-shaped ones, punched sheets, and expanded metals.
  • Examples of materials for the negative electrode current collector include stainless steel, nickel, nickel alloys, copper, and copper alloys.
  • the separator has high ion permeability and has appropriate mechanical strength and insulation properties.
  • a microporous thin film, a woven fabric, or a nonwoven fabric, or a laminate of at least two of these materials can be used as the separator.
  • the material of the separator is preferably polyolefin (e.g., polypropylene, polyethylene).
  • Non-aqueous electrolyte secondary battery is a structure in which an electrode group consisting of a positive electrode and a negative electrode wound with a separator between them is housed in an exterior body together with an electrolyte.
  • this is not limited to this, and other types of electrode groups may be used.
  • it may be a laminated type electrode group in which a positive electrode and a negative electrode are laminated with a separator between them.
  • the shape of the non-aqueous electrolyte secondary battery is also not limited, and may be, for example, a cylindrical type, a square type, a coin type, a button type, a laminate type, etc.
  • FIG. 1 is a vertical cross-sectional view of a cylindrical secondary battery that is an example of this embodiment.
  • the present disclosure is not limited to the following configuration.
  • a positive electrode lead 15a derived from the positive electrode 15 is connected to the metal plate 13.
  • the valve body 12 functions as an external terminal of the positive electrode.
  • a negative electrode lead 16a derived from the negative electrode 16 is connected to the inner bottom surface of the battery can 22.
  • An annular groove 22a is formed near the open end of the battery can 22.
  • a first insulating plate 23 is disposed between one end face of the electrode group 18 and the annular groove 22a.
  • a second insulating plate 24 is disposed between the other end face of the electrode group 18 and the bottom of the battery can 22.
  • the electrode group 18 is formed by winding a positive electrode 15 and a negative electrode 16 with a separator 17 interposed therebetween.
  • a method for preparing a liquid dispersion liquid comprising: a non-aqueous solvent; a salt that dissolves in the non-aqueous solvent; and an additive that dissolves in the non-aqueous solvent;
  • the additive includes a cyclic carboxylic acid anhydride and a sulfur-containing compound,
  • the sulfur-containing compound includes at least one selected from the group consisting of a hexavalent sulfur compound and a tetravalent sulfur compound,
  • the cyclic carboxylic acid anhydride is represented by the general formula (1):
  • the structure is represented by The tetravalent sulfur compound is represented by the general formula (3):
  • R1 to R4 each independently represent a hydrogen atom, a fluorine atom, or a hydrocarbon group
  • X1 is a fluorine atom, a hydrocarbon group or an oxyhydrocarbon group
  • X2, X3 and X4 each independently represent a hydrocarbon group, a silyl group or an alkali metal
  • At least one hydrogen atom of the hydrocarbon group may be substituted with a halogen atom
  • X1 and X2 may form a ring
  • the nonaqueous electrolyte for secondary batteries, wherein X3 and X4 may form a ring.
  • a secondary battery comprising: a positive electrode; a separator; a negative electrode facing the positive electrode with the separator interposed therebetween; a nonaqueous electrolyte; and a battery can accommodating the positive electrode, the separator, the negative electrode, and the nonaqueous electrolyte, wherein the nonaqueous electrolyte is the nonaqueous electrolyte for secondary batteries according to any one of Techniques 1 to 6.
  • Examples 1 to 5 and Comparative Examples 1 to 9 A non-aqueous electrolyte secondary battery was produced and evaluated according to the following procedure.
  • PAA-Na sodium polyacrylate
  • CMC-Na a sodium salt of CMC
  • SBR sulfur-semiconductor
  • the contents of PAA-Na, CMC-Na, and SBR in the negative electrode mixture were each 1 mass%.
  • the negative electrode slurry was applied to the surface of the copper foil, the coating was dried, and then rolled to form a negative electrode mixture layer (thickness 80 ⁇ m, density 1.6 g/cm 3 ) on both sides of the copper foil, thereby obtaining a negative electrode.
  • the concentration of LiPF 6 in the non-aqueous electrolyte was 1.35 mol/L.
  • the concentration (initial concentration) of the additive in the non-aqueous electrolyte was the value (mass%) shown in Table 1.
  • the positive electrode lead was connected to the metal plate of the safety mechanism equipped in the sealing body, and the non-aqueous electrolyte was injected into the battery can, and then the battery can was supported by the annular groove formed in the battery can via a gasket, and the open end of the battery can was crimped to the periphery of the sealing body to complete the lithium ion secondary battery.
  • LiFSO 3 Lithium fluorosulfonate PRS: 1-propene-1,3-sultone DTD: Ethylene sulfate MMDS: 1,5,2,4-dioxadithiane-2,2,4,4-tetraoxide
  • batteries E1 to E4 exhibited high high-temperature cycle characteristics and significantly reduced the amount of Fe eluted in an overdischarged state.
  • the nonaqueous electrolyte secondary battery according to the present disclosure is useful as a main power source for mobile communication devices, portable electronic devices, etc.
  • the uses of the nonaqueous electrolyte secondary battery are not limited to these.

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PCT/JP2023/038514 2022-11-24 2023-10-25 二次電池用非水電解質および二次電池 Ceased WO2024111334A1 (ja)

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CN202380080506.5A CN120226185A (zh) 2022-11-24 2023-10-25 二次电池用非水电解质和二次电池
EP23894346.8A EP4625585A4 (en) 2022-11-24 2023-10-25 NON-AQUEOUS ELECTROLYTE FOR SECONDARY BATTERIES AND SECONDARY BATTERIES
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003132948A (ja) * 2001-10-26 2003-05-09 Toshiba Corp 非水電解質二次電池
JP2003151623A (ja) * 2001-11-14 2003-05-23 Japan Storage Battery Co Ltd 非水系二次電池
JP2007287518A (ja) * 2006-04-18 2007-11-01 Sanyo Electric Co Ltd 非水系二次電池
JP4190162B2 (ja) 2001-03-01 2008-12-03 三井化学株式会社 非水電解液、それを用いた二次電池、および電解液用添加剤

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US12444745B2 (en) * 2019-03-29 2025-10-14 Zeon Corporation Shaping material for electrode, electrode and methods of producing and recycling same, and electrochemical device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4190162B2 (ja) 2001-03-01 2008-12-03 三井化学株式会社 非水電解液、それを用いた二次電池、および電解液用添加剤
JP2003132948A (ja) * 2001-10-26 2003-05-09 Toshiba Corp 非水電解質二次電池
JP2003151623A (ja) * 2001-11-14 2003-05-23 Japan Storage Battery Co Ltd 非水系二次電池
JP2007287518A (ja) * 2006-04-18 2007-11-01 Sanyo Electric Co Ltd 非水系二次電池

Non-Patent Citations (1)

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Title
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