WO2024111423A1 - 二次電池 - Google Patents

二次電池 Download PDF

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Publication number
WO2024111423A1
WO2024111423A1 PCT/JP2023/040382 JP2023040382W WO2024111423A1 WO 2024111423 A1 WO2024111423 A1 WO 2024111423A1 JP 2023040382 W JP2023040382 W JP 2023040382W WO 2024111423 A1 WO2024111423 A1 WO 2024111423A1
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Prior art keywords
negative electrode
separator
positive electrode
current collector
secondary battery
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PCT/JP2023/040382
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English (en)
French (fr)
Japanese (ja)
Inventor
将平 楠本
圭衣子 加藤
拓也 岩本
肇 西野
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Panasonic Intellectual Property Management Co Ltd
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Panasonic Intellectual Property Management Co Ltd
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Priority to EP23894432.6A priority Critical patent/EP4625570A4/en
Priority to CN202380078900.5A priority patent/CN120188296A/zh
Priority to JP2024560064A priority patent/JPWO2024111423A1/ja
Publication of WO2024111423A1 publication Critical patent/WO2024111423A1/ja
Anticipated expiration legal-status Critical
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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
    • 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
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • H01M4/64—Carriers or collectors
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • 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
    • H01M50/443—Particulate 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
    • H01M50/446—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
    • 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
    • H01M50/463—Separators, membranes or diaphragms characterised by their shape
    • 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
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0037—Mixture of solvents
    • H01M2300/004—Three solvents
    • 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
    • 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
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • 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 secondary batteries.
  • secondary batteries such as lithium-ion secondary batteries, which have an electrode assembly in which a positive electrode and a negative electrode are arranged opposite each other with a separator between them, have been widely used as high-output, high-energy density secondary batteries.
  • Patent Document 1 discloses the use of a Si-containing material as the negative electrode active material in order to increase the capacity of secondary batteries.
  • the electrode body may buckle during charging and discharging.
  • the current collectors used in the positive and negative electrodes may be damaged, causing an increase in battery resistance.
  • the purpose of this disclosure is to prevent the occurrence of buckling of the electrode body and suppress an increase in battery resistance in secondary batteries that use a Si-containing material as the negative electrode active material.
  • the secondary battery according to the present disclosure comprises an electrode assembly having a positive electrode, a negative electrode, and a separator provided between the positive electrode and the negative electrode, the positive electrode has a positive electrode current collector and a positive electrode composite layer disposed on the positive electrode current collector, the negative electrode has a negative electrode current collector and a negative electrode composite layer disposed on the negative electrode current collector, the negative electrode composite layer has a negative electrode active material containing a Si-containing material, at least one of the positive electrode current collector and the negative electrode current collector has a 1% elongation yield strength CM (MPa) of the current collector and an average thickness CT ( ⁇ m) of the current collector satisfying the relationship CM ⁇ CT ⁇ 1700, the separator has a first separator surface facing the positive electrode and a second separator surface facing the negative electrode, and at least one of the first separator surface and the second separator surface has a ten-point average roughness (Rz) of 2.7 ⁇ m or more.
  • a secondary battery that uses a Si-containing material as the negative electrode active material, it is possible to suppress the occurrence of buckling of the electrode body and to suppress an increase in battery resistance.
  • FIG. 1 is a cross-sectional view of a secondary battery according to an embodiment
  • FIG. 2 is a schematic diagram showing a state in which a separator is disposed between a positive electrode and a negative electrode.
  • FIG. 2 is a schematic cross-sectional view showing an example of a separator according to the present embodiment.
  • the secondary battery comprises an electrode assembly having a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, the positive electrode has a positive electrode current collector and a positive electrode composite layer disposed on the positive electrode current collector, the negative electrode has a negative electrode current collector and a negative electrode composite layer disposed on the negative electrode current collector, the negative electrode composite layer has a negative electrode active material containing a Si-containing material, at least one of the positive electrode current collector and the negative electrode current collector has a 1% elongation yield strength CM (MPa) of the current collector and an average thickness CT ( ⁇ m) of the current collector satisfying the relationship CM ⁇ CT ⁇ 1700, the separator has a first separator surface facing the positive electrode and a second separator surface facing the negative electrode, and at least one of the first separator surface and the second separator surface has a ten-point average roughness (Rz) of 2.7 ⁇ m or more.
  • CM ⁇ CT ⁇ 1700 suppresses buckling of the electrode body during charging and discharging of the battery.
  • a separator whose surface has a ten-point average roughness (Rz) of 2.7 ⁇ m or more suppresses damage to the current collector, thereby suppressing an increase in battery resistance.
  • Rz ten-point average roughness
  • CM ⁇ CT ⁇ 1700 If a current collector that satisfies the relationship CM ⁇ CT ⁇ 1700 is subjected to stress due to volumetric change of the Si-containing material over a long period of time, the current collector may be damaged.
  • a separator whose surface has a ten-point average roughness (Rz) of 2.7 ⁇ m or more, an appropriate amount of space is formed within the electrode body, which is thought to alleviate the stress on the current collector caused by the volumetric change of the Si-containing material during charging and discharging. This is thought to lead to the suppression of an increase in battery resistance by suppressing damage to the current collector, etc.
  • the secondary battery 10 shown in FIG. 1 includes a wound electrode body 14 in which a positive electrode 11 and a negative electrode 12 are wound with a separator 13 interposed therebetween, a non-aqueous electrolyte, insulating plates 18, 19 arranged above and below the electrode body 14, and a battery case 15 that houses the above-mentioned components.
  • the battery case 15 is composed of a cylindrical case body 16 with a bottom and a sealing body 17 that closes the opening of the case body 16.
  • other types of electrode bodies may be used, such as a laminated electrode body in which positive and negative electrodes are alternately laminated with separators interposed therebetween.
  • Examples of the battery case 15 include a cylindrical, square, coin-shaped, button-shaped, or other metal case, and a resin case formed by laminating resin sheets (so-called laminate type).
  • the non-aqueous electrolyte has, for example, ionic conductivity (for example, lithium ion conductivity).
  • the non-aqueous electrolyte may be a liquid electrolyte (electrolytic solution) or a solid electrolyte.
  • the liquid electrolyte contains, for example, a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.
  • a non-aqueous solvent for example, esters, ethers, nitriles, amides, and mixed solvents of two or more of these are used as the non-aqueous solvent.
  • the non-aqueous solvent include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixed solvents of these.
  • the non-aqueous solvent may contain a halogen-substituted product (e.g., fluoroethylene carbonate, etc.) in which at least a part of the hydrogen of these solvents is replaced with a halogen atom such as fluorine.
  • a halogen-substituted product e.g., fluoroethylene carbonate, etc.
  • a lithium salt such as LiPF6 is used as the electrolyte salt.
  • the solid electrolyte for example, a solid or gel-like polymer electrolyte, an inorganic solid electrolyte, etc.
  • the polymer electrolyte includes, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt, and a matrix polymer.
  • the matrix polymer for example, a polymer material that absorbs a non-aqueous solvent and gels is used.
  • the polymer material for example, fluororesin, acrylic resin, polyether resin, etc. can be used.
  • the inorganic solid electrolyte for example, a material known in all-solid-state lithium ion secondary batteries, etc.
  • an oxide-based solid electrolyte for example, an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a halogen-based solid electrolyte, etc.
  • non-aqueous electrolyte for example, an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a halogen-based solid electrolyte, etc.
  • non-aqueous electrolyte is just one example, and an aqueous electrolyte may be used if applicable.
  • the case body 16 is, for example, a cylindrical metal container with a bottom.
  • a gasket 28 is provided between the case body 16 and the sealing body 17 to ensure airtightness inside the battery.
  • the case body 16 has a protruding portion 22 that supports the sealing body 17, for example, a part of the side surface that protrudes inward.
  • the protruding portion 22 is preferably formed in an annular shape along the circumferential direction of the case body 16, and supports the sealing body 17 on its upper surface.
  • the sealing body 17 has a structure in which, in order from the electrode body 14 side, a filter 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a cap 27 are stacked.
  • Each member constituting the sealing body 17 has, for example, a disk shape or a ring shape, and each member except the insulating member 25 is electrically connected to each other.
  • the lower valve body 24 and the upper valve body 26 are connected to each other at their respective centers, and the insulating member 25 is interposed between each of their peripheral edges.
  • the lower valve body 24 deforms and breaks so as to push the upper valve body 26 toward the cap 27, and the current path between the lower valve body 24 and the upper valve body 26 is interrupted.
  • the upper valve body 26 breaks, and gas is discharged from the opening of the cap 27.
  • the positive electrode lead 20 attached to the positive electrode 11 extends through a through hole in the insulating plate 18 toward the sealing body 17, and the negative electrode lead 21 attached to the negative electrode 12 extends through the outside of the insulating plate 19 toward the bottom side of the case body 16.
  • the positive electrode lead 20 is connected by welding or the like to the underside of the filter 23, which is the bottom plate of the sealing body 17, and the cap 27, which is the top plate of the sealing body 17 and is electrically connected to the filter 23, serves as the positive electrode terminal.
  • the negative electrode lead 21 is connected by welding or the like to the inner bottom surface of the case body 16, and the case body 16 serves as the negative electrode terminal.
  • the positive electrode 11, negative electrode 12, and separator 13 are described in detail below.
  • the positive electrode 11 has a positive electrode current collector and a positive electrode composite layer disposed on the positive electrode current collector.
  • the positive electrode composite layer may be disposed on one side or both sides of the positive electrode current collector.
  • the positive electrode current collector may be a foil of a metal such as aluminum that is stable in the potential range of the positive electrode 11, or a film having the metal disposed on the surface layer. The 1% elongation yield strength and average thickness of the positive electrode current collector will be described later.
  • the positive electrode composite layer contains, for example, a positive electrode active material, a binder, a conductive material, etc.
  • the positive electrode 11 can be produced, for example, by applying a positive electrode composite slurry containing a positive electrode active material, a binder, a conductive material, etc., onto a positive electrode current collector, drying the coating, and then rolling it.
  • the positive electrode active material may be, for example, a lithium transition metal oxide containing a transition metal element such as Co, Mn, or Ni.
  • lithium transition metal oxides include LixCoO2 , LixNiO2 , LixMnO2, LixCoyNi1-yO2, LixCoyM1- yOz , LixNi1 - yMyOz , LixMn2O4 , LixMn2 - yMyO4 , LiMPO4, and Li2MPO4F (M; at least one of Na, Mg, Sc , Y, Mn, Fe, Co, Ni, Cu, Zn , Al , Cr , Pb, Sb, and B ; 0 ⁇ x ⁇ 1.2 , 0 ⁇ y ⁇ 0.9, 2.0 ⁇ z ⁇ 2.3).
  • the positive electrode active material preferably contains a lithium nickel composite oxide such as Li x NiO 2 , Li x Co y Ni 1-y O 2 , or Li x Ni 1-y M y O z (M: at least one of Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, and B; 0 ⁇ x ⁇ 1.2, 0 ⁇ y ⁇ 0.9, and 2.0 ⁇ z ⁇ 2.3).
  • a lithium nickel composite oxide such as Li x NiO 2 , Li x Co y Ni 1-y O 2 , or Li x Ni 1-y M y O z (M: at least one of Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, and B; 0 ⁇ x ⁇ 1.2, 0 ⁇ y ⁇ 0.9, and 2.0 ⁇ z ⁇ 2.3).
  • Conductive materials include, for example, carbon-based particles such as carbon black (CB), acetylene black (AB), ketjen black, carbon nanotubes (CNT), and graphite. These may be used alone or in combination of two or more types.
  • CB carbon black
  • AB acetylene black
  • CNT carbon nanotubes
  • graphite graphite
  • binders include fluorine-based resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, polyolefin resins, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC) or its salts, polyacrylic acid (PAA) or its salts (PAA-Na, PAA-K, etc., or partially neutralized salts), polyvinyl alcohol (PVA), etc. These may be used alone or in combination of two or more types.
  • fluorine-based resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, polyolefin resins, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC) or its salts, polyacrylic
  • the negative electrode 12 has a negative electrode current collector and a negative electrode composite layer disposed on the negative electrode current collector.
  • the negative electrode composite layer may be disposed on one side or both sides of the negative electrode current collector.
  • the negative electrode current collector may be a foil of a metal such as copper or a copper alloy that is stable in the potential range of the negative electrode, or a film having the metal disposed on the surface layer. The 1% elongation yield strength and average thickness of the negative electrode current collector will be described later.
  • the negative electrode composite layer contains, for example, a negative electrode active material, a binder, a conductive material, etc.
  • the negative electrode 12 can be produced, for example, by applying a negative electrode composite slurry containing a negative electrode active material, a binder, etc., onto a negative electrode current collector, drying the coating, and then rolling it.
  • the negative electrode active material includes a Si-containing material.
  • the Si-containing material include Si, a Si alloy, and a Si compound.
  • the Si-containing material may also be a composite particle including an ion-conducting phase and a silicon phase (silicon particles in one respect) dispersed in the ion-conducting phase.
  • the ion-conducting phase is a phase that conducts ions, and examples of the phase include a silicate phase, a carbon phase, and a silicon oxide phase.
  • the Si-containing material preferably includes at least one of a first composite particle having a carbon phase and a silicon phase dispersed in the carbon phase, a second composite particle having a silicate phase and a silicon phase dispersed in the silicate phase, and a third composite particle having a silicon oxide phase and a silicon phase dispersed in the silicon oxide phase.
  • the carbon phase may be composed of, for example, amorphous carbon.
  • amorphous carbon examples include hard carbon, soft carbon, and other amorphous carbon.
  • Amorphous carbon is a carbon material having an average interplanar spacing d 002 of the (002) planes measured by X-ray diffraction method exceeding 0.34 nm.
  • the main component of the silicon oxide phase may be silicon dioxide.
  • the composition of the composite particle including the silicon oxide phase and the silicon phase dispersed therein can be expressed as SiOx as a whole.
  • SiOx has a structure in which silicon particles are dispersed in amorphous SiO2 .
  • the content ratio x of oxygen to silicon is, for example, preferably 0.5 ⁇ x ⁇ 2.0, more preferably 0.8 ⁇ x ⁇ 1.5.
  • the silicate phase may satisfy the following conditions (1) and/or (2).
  • the silicate phase contains at least one element selected from the group consisting of alkali metal elements and Group 2 elements (Group 2 elements of the long form periodic table).
  • the silicate phase contains an element L.
  • the element L is at least one selected from the group consisting of B, Al, Zr, Nb, Ta, V, lanthanoids, Y, Ti, P, Bi, Zn, Sn, Pb, Sb, Co, Er, F, and W.
  • Lanthanoids is a general term for 15 elements ranging from lanthanum (La) with atomic number 57 to lutetium (Lu) with atomic number 71.
  • examples of alkali metal elements include lithium (Li), potassium (K), and sodium (Na).
  • Examples of Group 2 elements include magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).
  • a silicate phase containing lithium hereinafter, may be referred to as "lithium silicate phase" is preferable in that it has, for example, a small irreversible capacity and a high initial charge/discharge efficiency.
  • the lithium silicate phase may be an oxide phase containing Li, Si, and 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.
  • the Si-containing material may also include composite particles containing an ion-conducting phase and a silicon phase dispersed within the ion-conducting phase, and a coating layer covering at least a portion of the surface of the composite particles.
  • the coating layer present on the surface of the composite particle includes, for example, a conductive layer.
  • a conductive layer By forming a conductive layer on the surface of the composite particle, the conductivity of the Si-containing material may be increased.
  • the conductive material constituting the conductive layer is preferably a conductive material containing carbon.
  • conductive materials containing carbon include conductive carbon materials.
  • conductive carbon materials include carbon black, graphite, amorphous carbon (amorphous carbon) with low crystallinity, etc.
  • Amorphous carbon is preferable because it has a large buffering effect on the silicon phase that changes in volume during charging and discharging.
  • the amorphous carbon may be easily graphitized carbon (soft carbon) or difficult to graphitize carbon (hard carbon).
  • the thickness of the conductive layer may be, for example, in the range of 1 to 200 nm.
  • the thickness of the conductive layer can be measured by observing the cross section of the Si-containing material using a SEM or a TEM (transmission electron microscope).
  • the content of the Si-containing material is preferably 3 mass% or more relative to the total mass of the negative electrode active material, for example, in terms of increasing the capacity of the battery.
  • the upper limit of the content of the Si-containing material is preferably, for example, 20 mass% or less.
  • the negative electrode active material may contain, in addition to the Si-containing material, a known material capable of reversibly absorbing and releasing lithium ions.
  • the negative electrode active material preferably contains a carbon material, for example, in order to further suppress the deterioration of the charge/discharge cycle characteristics of the battery.
  • Examples of the carbon material include graphite materials such as natural graphite and artificial graphite.
  • the content of the carbon material is preferably, for example, 80 mass% or more relative to the total mass of the negative electrode active material.
  • the negative electrode active material may also contain a Sn-containing material, a Ti-containing material, etc., as a known material capable of reversibly absorbing and releasing lithium ions.
  • Binders include, for example, fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, polyolefin resins, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC) or its salts, polyacrylic acid (PAA) or its salts (PAA-Na, PAA-K, etc., or partially neutralized salts), polyvinyl alcohol (PVA), etc. These may be used alone or in combination of two or more types.
  • fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, polyolefin resins, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC) or its salts, polyacrylic
  • Conductive materials include, for example, carbon-based particles such as carbon black (CB), acetylene black (AB), ketjen black, carbon nanotubes (CNT), and graphite. These may be used alone or in combination of two or more types.
  • CB carbon black
  • AB acetylene black
  • CNT carbon nanotubes
  • graphite graphite
  • CM (MPa) ⁇ average thickness of current collector CT ( ⁇ m)
  • CM (MPa) 1% elongation yield strength of current collector CM (MPa) ⁇ average thickness of current collector CT ( ⁇ m)
  • CM ⁇ CT ⁇ 1700 preferably 500 ⁇ CM ⁇ CT ⁇ 1700, and more preferably 870 ⁇ CM ⁇ CT ⁇ 1560.
  • the 1% elongation yield strength CM of the collector is a yield strength (1%) measured by the tensile test method for metal materials of JIS Z 2241.
  • the 1% elongation yield strength CM of the collector can be adjusted, for example, by the thickness of the collector or the crystal grain size of the material of the collector.
  • the average thickness CT of the collector is a value obtained by cutting the collector along a plane perpendicular to the surface direction, measuring the thickness at 10 or more points on the cross section, and averaging the measured values.
  • the average thickness CT of at least one of the positive and negative current collectors is preferably 5.0 ⁇ m or more and 25.0 ⁇ m or less, and more preferably 7.8 ⁇ m or more and 15.0 ⁇ m or less, in order to suppress the occurrence of buckling of the electrode body 14.
  • the 1% elongation yield strength CM of at least one of the positive and negative current collectors is preferably 50 MPa or more and 300 MPa or less, and more preferably 58 MPa or more and 200 MPa or less, in order to suppress the occurrence of buckling of the electrode body 14.
  • FIG. 2 is a schematic diagram showing a state in which a separator is disposed between a positive electrode and a negative electrode.
  • the positive electrode 11, the negative electrode 12, and the separator 13 shown in Fig. 2 are in a state before being wound.
  • the positive electrode 11 and the negative electrode 12 are wound with the separator 13 interposed therebetween to form an electrode body 14. Note that in Fig. 2, the gaps between the positive electrode 11 and the separator 13, and between the negative electrode 12 and the separator 13 are exaggerated.
  • the separator 13 has a first separator surface 13a facing the positive electrode 11 and a second separator surface 13b facing the negative electrode 12. At least one of the first separator surface 13a and the second separator surface 13b has a ten-point average roughness (Rz) of 2.7 ⁇ m or more.
  • the ten-point average roughness (Rz) is obtained by extracting only a reference length from the roughness curve in the direction of the average line, and measuring in the direction of the longitudinal magnification from the average line of this extracted portion, and calculating the sum of the average value of the absolute values of the elevations (Yp) of the five highest peaks and the average value of the absolute values of the elevations (Yv) of the five lowest valleys, and expressing this value in micrometers ( ⁇ m).
  • the separator surface can be observed using a laser microscope (OLYMPUS Corporation, OLS4100) and the ten-point average roughness (Rz) can be measured using a method conforming to JIS B0601:2001.
  • both the first separator surface 13a and the second separator surface 13b may have a ten-point average roughness (Rz) of 2.7 ⁇ m or more.
  • Rz ten-point average roughness
  • the ten-point average roughness (Rz) of at least one of the first separator surface 13a and the second separator surface 13b is 2.7 ⁇ m or more, preferably 3.0 or more and 10 or less, and more preferably 3.5 or more and 8 or less, in order to suppress an increase in battery resistance.
  • FIG. 3 is a schematic cross-sectional view showing an example of a separator of this embodiment.
  • the separator 13 has a substrate 30 having a first surface 30a and a second surface 30b, and a functional layer 32 disposed on the first surface 30a of the substrate 30.
  • the functional layer 32 may be disposed on both the first surface 30a and the second surface 30b.
  • the substrate 30 is, for example, a porous sheet having ion permeability and insulating properties, and specific examples thereof include a microporous thin film, a woven fabric, a nonwoven fabric, etc.
  • the material of the substrate 30 is not particularly limited, but examples thereof include polyolefins such as polyethylene, polypropylene, copolymers of polyethylene and alpha-olefin, acrylic resins, polystyrene, polyester, cellulose, polyimide, polyphenylene sulfide, polyether ether ketone, fluororesins, etc.
  • the functional layer 32 includes a heat-resistant layer 34 containing inorganic particles, and resin particles 36 dispersed in the heat-resistant layer 34. Some of the resin particles 36 form protrusions 36a protruding from the surface of the heat-resistant layer 34.
  • the outer surface of the functional layer 32 i.e., the surface opposite to the surface facing the substrate 30, is formed by the surface of the heat-resistant layer 34 and the protrusions 36a protruding from the surface of the heat-resistant layer 34.
  • the outer surface of the functional layer 32 has a ten-point average roughness (Rz) of 2.7 ⁇ m or more.
  • the outer surface of the functional layer 32 is roughened and the ten-point average roughness (Rz) is increased.
  • the outer surface of the functional layer 32 is the first separator surface 13a facing the positive electrode 11 or the second separator surface 13b facing the negative electrode 12, as described above, and is preferably the first separator surface 13a facing the positive electrode 11.
  • the average particle diameter (D50) of the resin particles 36 is preferably larger than the average thickness of the heat-resistant layer 34 in order to easily roughen the outer surface of the functional layer 32, and the difference between the average particle diameter (D50) of the resin particles 36 and the average thickness of the heat-resistant layer 34 is preferably, for example, 0.5 ⁇ m or more, and more preferably 1.0 ⁇ m or more.
  • the upper limit of the difference between the average particle diameter (D50) of the resin particles 36 and the thickness of the heat-resistant layer 34 is not particularly limited, but is preferably 10 ⁇ m or less, and more preferably 5 ⁇ m or less, in terms of, for example, a decrease in the ionic conductivity of the separator.
  • the average particle diameter (D50) of the resin particles 36 is preferably, for example, in the range of 1.0 ⁇ m or more and 8.0 ⁇ m or less, depending on the thickness of the heat-resistant layer 34.
  • D50 means a particle diameter at which the cumulative frequency in the volume-based particle size distribution is 50% from the smallest particle diameter, and is also called the median diameter.
  • the particle size distribution of the resin particles 36 can be measured using a laser diffraction particle size distribution measuring device (e.g., MT3000II, manufactured by Microtrack Bell Co., Ltd.) with water as the dispersion medium.
  • the average thickness of the heat-resistant layer 34 is determined by cutting the separator 13 along a plane perpendicular to the surface direction, measuring the thickness of the heat-resistant layer 34 at 10 or more points on the cross section, and averaging the measured values.
  • the content of the resin particles 36 is preferably, for example, in a range of 4:96 to 20:80 in terms of the mass ratio of the resin particles 36 to the heat-resistant layer 34 (resin particles:heat-resistant layer).
  • the area occupancy of the resin particles 36 when the surface of the functional layer 32 is viewed in a planar view is preferably 2% or more and 30% or less, and more preferably 10% or more and 25% or less, in order to roughen the outer surface of the functional layer 32.
  • the area occupancy of the resin particles 36 can be calculated by observing the surface of the functional layer 32 with a scanning electron microscope and measuring the total area of the protrusions 36a present within an area of 100 ⁇ m x 100 ⁇ m.
  • the resin particles 36 may be, for example, a known polymer that can be used as a binder when forming the functional layer 32.
  • monomer units constituting the resin particles 36 (polymer) include aromatic vinyl monomer units, (meth)acrylic acid ester monomer units, and fluorine-containing monomer units.
  • (meth)acrylic means acrylic and/or methacrylic.
  • aromatic vinyl monomers capable of forming aromatic vinyl monomer units include, but are not limited to, styrene, ⁇ -methylstyrene, styrenesulfonic acid, butoxystyrene, vinylnaphthalene, etc.
  • Examples of (meth)acrylic acid ester monomers capable of forming (meth)acrylic acid ester monomer units include butyl acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate and t-butyl acrylate, octyl acrylates such as pentyl acrylate, hexyl acrylate, heptyl acrylate and 2-ethylhexyl acrylate, acrylic acids such as nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate and stearyl acrylate, etc.
  • alkyl esters and methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, butyl methacrylate such as n-butyl methacrylate and t-butyl methacrylate, octyl methacrylate such as pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, and 2-ethylhexyl methacrylate, and methacrylic acid alkyl esters such as nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, and stearyl methacrylate.
  • methacrylic acid alkyl esters such as nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, and stearyl methacryl
  • fluorine-containing monomers that can form fluorine-containing monomer units include, but are not limited to, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, vinyl chloride trifluoride, vinyl fluoride, perfluoroalkyl vinyl ether, etc.
  • the resin particles 36 may contain crosslinkable monomer units in addition to the above monomer units.
  • the crosslinkable monomer units are monomers that can form crosslinked structures during or after polymerization by heating or irradiation with energy rays.
  • Examples of monomers that can form crosslinkable monomer units include polyfunctional monomers having two or more polymerization reactive groups in the monomer.
  • polyfunctional monomers examples include divinyl compounds such as allyl methacrylate and divinylbenzene; di(meth)acrylic acid ester compounds such as diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, and 1,3-butylene glycol diacrylate; tri(meth)acrylic acid ester compounds such as trimethylolpropane trimethacrylate and trimethylolpropane triacrylate; ethylenically unsaturated monomers containing epoxy groups such as allyl glycidyl ether and glycidyl methacrylate; and the like.
  • divinyl compounds such as allyl methacrylate and divinylbenzene
  • di(meth)acrylic acid ester compounds such as diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, and 1,3-butylene glycol diacrylate
  • tri(meth)acrylic acid ester compounds such
  • the resin particles 36 can be prepared by polymerizing a monomer composition containing the above-mentioned monomers in an aqueous solvent such as water.
  • the polymerization method is not particularly limited, and may be, for example, a suspension polymerization method, an emulsion polymerization aggregation method, or a pulverization method.
  • the polymerization reaction may be any reaction such as radical polymerization or living radical polymerization.
  • the monomer composition used in preparing the resin particles 36 may contain other additives in any amount, such as chain transfer agents, polymerization regulators, polymerization reaction retarders, reactive flow agents, fillers, flame retardants, antioxidants, and colorants.
  • Examples of inorganic particles contained in the heat-resistant layer 34 include metal oxide particles, metal nitride particles, metal fluoride particles, metal carbide particles, etc.
  • metal oxide particles include aluminum oxide, titanium oxide, magnesium oxide, zirconium oxide, nickel oxide, silicon oxide, and manganese oxide.
  • metal nitride particles include titanium nitride, boron nitride, aluminum nitride, magnesium nitride, and silicon nitride.
  • metal fluoride particles include aluminum fluoride, lithium fluoride, sodium fluoride, magnesium fluoride, calcium fluoride, and barium fluoride.
  • metal carbide particles include silicon carbide, boron carbide, titanium carbide, and tungsten carbide.
  • the inorganic particles may be porous aluminosilicates such as zeolite ( M2 /nO.Al2O3.xSiO2.yH2O , where M is a metal element, n is the valence of M, x ⁇ 2, y ⁇ 0), layered silicates such as talc ( Mg3Si4O10 (OH) 2 ), minerals such as barium titanate ( BaTiO3 ) and strontium titanate ( SrTiO3 ), etc. These may be used alone or in combination of two or more kinds.
  • zeolite M2 /nO.Al2O3.xSiO2.yH2O , where M is a metal element, n is the valence of M, x ⁇ 2, y ⁇ 0
  • layered silicates such as talc ( Mg3Si4O10 (OH) 2 )
  • minerals such as barium titanate ( BaTiO3 ) and strontium titanate ( SrT
  • the heat-resistant layer 34 preferably further contains a binder.
  • the binder has a function of, for example, bonding individual inorganic particles to each other and bonding inorganic particles to the substrate 30.
  • binders include fluorine-based resins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), polyimide resins, acrylic resins, polyolefin resins, styrene-butadiene rubber (SBR), nitrile-butadiene rubber (NBR), carboxymethyl cellulose (CMC) or a salt thereof, polyvinyl alcohol (PVA), and the like. These may be used alone or in combination of two or more.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • polyimide resins acrylic resins, polyolefin resins, styrene-butadiene rubber (SBR), nitrile-butadiene rubber (
  • the content of inorganic particles contained in the heat-resistant layer 34 is preferably, for example, 400% by mass or more and 9900% by mass or less with respect to the mass of the binder.
  • the content of the binder contained in the heat-resistant layer 34 is preferably, for example, 3% by mass or more and 30% by mass or less with respect to the total mass of the heat-resistant layer 34.
  • the heat-resistant layer 34 preferably contains a binder and a polymer having aramid bonds.
  • the polymer having aramid bonds has, for example, a function of improving the heat resistance of the heat-resistant layer 34.
  • Examples of the polymer having aramid bonds include aromatic polyamides such as meta-oriented aromatic polyamides and para-oriented aromatic polyamides.
  • the content of the inorganic particles contained in the heat-resistant layer 34 is preferably, for example, 25% by mass or more and 900% by mass or less with respect to the total mass of the binder and the polymer having aramid bonds.
  • the content of the binder contained in the heat-resistant layer 34 is preferably, for example, 3% by mass or more and 30% by mass or less with respect to the total mass of the heat-resistant layer 34.
  • the content of the heat-resistant polymer contained in the heat-resistant layer 34 is preferably, for example, 10% by mass or more and 80% by mass or less with respect to the total mass of the heat-resistant layer 34.
  • inorganic particles, resin particles 36, water as a dispersion medium, and other components used as necessary are mixed to prepare a slurry composition for the functional layer.
  • the slurry for the functional layer is then applied onto a substrate and dried to produce the separator 13 of this embodiment.
  • separator 13 of this embodiment is a separator having a substrate 30 having a first surface 30a and a second surface 30b, and a functional layer 32 disposed on the first surface 30a of the substrate 30, in which the second surface 30b of the substrate 30 has a ten-point average roughness (Rz) of 2.7 ⁇ m or more, or the outer surface of the functional layer 32 and the second surface 30b of the substrate 30 have a ten-point average roughness (Rz) of 2.7 ⁇ m or more.
  • Rz ten-point average roughness
  • the second surface 30b of the substrate 30 may be the first separator surface 13a facing the positive electrode 11 or the second separator surface 13b facing the negative electrode 12, but when only the second surface 30b of the substrate 30 has a ten-point average roughness (Rz) of 2.7 ⁇ m or more among the outer surface of the functional layer 32 and the second surface 30b of the substrate 30, it is preferable that the second surface 30b of the substrate 30 is the first separator surface 13a facing the positive electrode 11.
  • the separator 13 of this embodiment is not limited to a separator having a substrate 30 and a functional layer 32 disposed on the substrate 30, and may be, for example, a separator consisting of only the substrate 30.
  • the heat-resistant layer 34 containing inorganic particles is not an essential component of the functional layer 32.
  • the functional layer 32 may have, for example, a layer containing a known additive, and in addition to the heat-resistant layer, examples of the functional layer include an antistatic layer, an adhesive layer, a slipping layer, a leveling layer, a flame-retardant layer, a layer that improves compatibility with the electrolyte, an antioxidant layer, and a moistening/softening layer.
  • the separator 13 When the separator 13 is composed only of the substrate 30, at least one of the first surface 30a and the second surface 30b of the substrate 30 has a ten-point average roughness (Rz) of 2.7 ⁇ m or more.
  • Methods for roughening the surface of the substrate 30 and adjusting the ten-point average roughness (Rz) to 2.7 ⁇ m or more include, for example, mixing the aforementioned resin particles 36 into the raw material of the substrate 30 to create the substrate 30, or embedding the aforementioned resin particles 36 in the substrate 30 that has already been created. In this case, it is desirable for the average particle diameter (D50) of the resin particles 36 to be greater than the thickness of the substrate 30.
  • other methods for adjusting the ten-point average roughness (Rz) of the separator surface to 2.7 ⁇ m or more include rolling with uneven rolling rollers. For example, after forming a layer such as the heat-resistant layer 34 on the substrate 30, the surface of the layer is rolled with uneven rolling rollers to adjust the ten-point average roughness (Rz) of the separator surface to 2.7 ⁇ m or more.
  • ⁇ Comparative Example 1> [Preparation of Positive Electrode] 100 parts by mass of LiNi 0.88 Co 0.09 Al 0.03 O 2 , 1 part by mass of acetylene black (AB), and 0.9 parts by mass of polyvinylidene fluoride (PVDF) were mixed, and an appropriate amount of N-methyl-2-pyrrolidone (NMP) was added to prepare a positive electrode composite slurry. Next, the positive electrode composite slurry was applied to both sides of an aluminum foil (positive electrode current collector) having a thickness of 15.0 ⁇ m and a 1% elongation proof strength of 190 MPa, and the coating was dried.
  • NMP N-methyl-2-pyrrolidone
  • the coating was rolled using a roller, and then cut to a predetermined electrode size to prepare a positive electrode in which a positive electrode composite layer was formed on both sides of the positive electrode current collector.
  • An exposed portion in which the positive electrode composite layer was not formed and the positive electrode current collector was exposed was provided in the longitudinal center of the positive electrode, and an aluminum positive electrode lead was welded to the exposed portion.
  • the coating film was rolled using a roller, and then cut to a predetermined electrode size, and a negative electrode in which a negative electrode composite layer was formed on both sides of the negative electrode current collector was produced.
  • An exposed portion in which the negative electrode composite layer was not formed and the negative electrode current collector was exposed was provided at one end of the longitudinal direction of the negative electrode (the end located on the inside of the winding of the electrode body), and a nickel negative electrode lead was welded to the exposed portion.
  • a polyethylene porous substrate with a thickness of 12 ⁇ m was prepared.
  • ⁇ -Al 2 O 3 powder (inorganic particles) and a binder were mixed in a solid content mass ratio of 75:25, and then an appropriate amount of water was added to prepare a functional layer slurry.
  • the functional layer slurry was applied to the entire area of one side of the substrate using a microgravure coater, and the coating was heated and dried in an oven at 50°C for 4 hours to obtain a separator having a functional layer with a heat-resistant layer with an average thickness of 3.0 ⁇ m formed on one side of the substrate.
  • the ten-point average roughness (Rz) of the outer surface of the functional layer was measured and found to be 2.2 ⁇ m.
  • a wound electrode assembly was prepared by spirally winding the positive and negative electrodes with a separator interposed therebetween, with the separator positioned so that the functional layer of the separator faced the positive electrode.
  • a non-aqueous electrolyte was prepared by adding 5 parts by mass of vinylene carbonate (VC) to 100 parts by mass of a mixed solvent prepared by mixing ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 3:7, and dissolving lithium hexafluorophosphate (LiPF 6 ) in the mixed solvent at a concentration of 1.5 mol/L.
  • VC vinylene carbonate
  • EC ethylene carbonate
  • DMC dimethyl carbonate
  • the electrode body was housed in an outer can with insulating plates disposed above and below it.
  • the negative electrode lead was welded to the bottom of the cylindrical outer can with a bottom, and the positive electrode lead was welded to a sealing member.
  • a non-aqueous electrolyte was poured into the outer can, the opening of the outer can was sealed with a sealing member via a gasket, and the battery was left to stand in a thermostatic chamber at 60° C. for 15 hours to prepare a secondary battery.
  • Comparative Example 2 A secondary battery was fabricated in the same manner as in Comparative Example 1, except that a copper foil having a thickness of 7.8 ⁇ m and a 1% elongation yield strength of 300 MPa was used for the negative electrode current collector.
  • Comparative Example 4 A secondary battery was fabricated in the same manner as in Comparative Example 1, except that an aluminum foil having a thickness of 15.0 ⁇ m and a 1% elongation yield strength of 120 MPa was used for the positive electrode current collector.
  • Comparative Example 5 A secondary battery was fabricated in the same manner as in Comparative Example 1, except that an aluminum foil having a thickness of 15.0 ⁇ m and a 1% elongation yield strength of 58 MPa was used for the positive electrode current collector.
  • a secondary battery was produced in the same manner as in Comparative Example 1, except that an aluminum foil having a thickness of 15.0 ⁇ m and a 1% elongation yield strength of 58 MPa was used for the positive electrode current collector, and a copper foil having a thickness of 7.8 ⁇ m and a 1% elongation yield strength of 200 MPa was used for the negative electrode current collector.
  • ⁇ Comparative Example 7> In preparing the slurry for the functional layer, ⁇ -Al 2 O 3 powder, a binder, and acrylic resin particles having an average particle size (D50) of 3.5 ⁇ m were mixed in a solid content mass ratio of 70.6:23.5:5.9. A secondary battery was fabricated in the same manner as in Comparative Example 1.
  • the difference between the average particle diameter (D50) of the acrylic resin particles and the average thickness (Db) of the heat-resistant layer was 0.5 ⁇ m.
  • the ten-point average roughness (Rz) of the outer surface of the functional layer was measured and found to be 2.7 ⁇ m.
  • ⁇ Comparative Example 8> A secondary battery was produced in the same manner as in Comparative Example 1, except that an aluminum foil having a thickness of 15.0 ⁇ m and a 1% elongation yield strength of 120 MPa was used for the positive electrode current collector, a copper foil having a thickness of 7.8 ⁇ m and a 1% elongation yield strength of 300 MPa was used for the negative electrode current collector, and in preparing the slurry for the functional layer, ⁇ -Al 2 O 3 powder, a binder, and acrylic resin particles having an average particle size (D50) of 5.0 ⁇ m were mixed in a solid mass ratio of 68.9:22.9:8.2.
  • the difference between the average particle size (D50) of the acrylic resin particles and the average thickness (Db) of the heat-resistant layer was 2 ⁇ m.
  • the ten-point average roughness (Rz) of the outer surface of the functional layer was measured and found to be 2.7 ⁇ m.
  • the secondary battery after 300 cycles was charged to 3.7 V, held at 3.7 V for 1 hour, and discharged at 4.8 mA.
  • the battery resistance after 300 cycles was calculated from the voltage drop after 5 seconds.
  • Table 1 summarizes the evaluation of the occurrence of buckling of the electrode body and the results of the battery resistance in Comparative Examples 1 to 6. However, the battery resistance values for Comparative Examples 2 to 6 are shown as relative values, with the result of Comparative Example 1 set as the standard (100).
  • ⁇ Comparative Example 9> A secondary battery was fabricated in the same manner as in Comparative Example 1, except that a copper foil having a thickness of 7.8 ⁇ m and a 1% elongation yield strength of 200 MPa was used for the negative electrode current collector, and that in preparing the slurry for the functional layer, ⁇ -Al 2 O 3 powder, a binder, and acrylic resin particles having an average particle size (D50) of 3.1 ⁇ m were mixed in a solid content mass ratio of 71.0:23.7:5.3.
  • the difference between the average particle size (D50) of the acrylic resin particles and the average thickness (Db) of the heat-resistant layer was 0.1 ⁇ m.
  • the ten-point average roughness (Rz) of the outer surface of the functional layer was measured and found to be 2.3 ⁇ m.
  • ⁇ Comparative Example 10> A secondary battery was fabricated and tested in the same manner as in Comparative Example 1, except that a copper foil having a thickness of 7.8 ⁇ m and a 1% elongation yield strength of 200 MPa was used for the negative electrode current collector, and that in preparing the slurry for the functional layer, ⁇ -Al 2 O 3 powder, a binder, and acrylic resin particles having an average particle size (D50) of 3.3 ⁇ m were mixed in a solid mass ratio of 71.0:23.6:5.4.
  • D50 average particle size
  • the difference between the average particle size (D50) of the acrylic resin particles and the average thickness (Db) of the heat-resistant layer was 0.3 ⁇ m.
  • the ten-point average roughness (Rz) of the outer surface of the functional layer was measured and found to be 2.4 ⁇ m.
  • Example 1 A secondary battery was fabricated in the same manner as in Comparative Example 1, except that a copper foil having a thickness of 7.8 ⁇ m and a 1% elongation yield strength of 200 MPa was used for the negative electrode current collector, and the slurry for the functional layer was prepared under the same conditions as in Comparative Example 7, and the same tests were performed.
  • the difference between the average particle diameter (D50) of the acrylic resin particles and the average thickness (Db) of the heat-resistant layer was 0.5 ⁇ m.
  • the ten-point average roughness (Rz) of the outer surface of the functional layer was measured and found to be 2.7 ⁇ m.
  • Example 2 A secondary battery was fabricated and tested in the same manner as in Comparative Example 1, except that a copper foil having a thickness of 7.8 ⁇ m and a 1% elongation yield strength of 200 MPa was used for the negative electrode current collector, and that in preparing the slurry for the functional layer, ⁇ -Al 2 O 3 powder, a binder, and acrylic resin particles having an average particle size (D50) of 4.0 ⁇ m were mixed in a solid mass ratio of 70.0:23.3:6.7.
  • the difference between the average particle diameter (D50) of the acrylic resin particles and the average thickness (Db) of the heat-resistant layer was 1 ⁇ m.
  • the ten-point average roughness (Rz) of the outer surface of the functional layer was measured and found to be 3.4 ⁇ m.
  • Example 3 A secondary battery was produced in the same manner as in Comparative Example 1, except that a copper foil having a thickness of 7.8 ⁇ m and a 1% elongation yield strength of 200 MPa was used for the negative electrode current collector, and the slurry for the functional layer was prepared under the same conditions as in Comparative Example 8, and the same tests were performed.
  • the difference between the average particle size (D50) of the acrylic resin particles and the average thickness (Db) of the heat-resistant layer was 2 ⁇ m.
  • the ten-point average roughness (Rz) of the outer surface of the functional layer was measured and found to be 4.7 ⁇ m.
  • Example 4 A secondary battery was fabricated and tested in the same manner as in Comparative Example 1, except that a copper foil having a thickness of 7.8 ⁇ m and a 1% elongation yield strength of 200 MPa was used for the negative electrode current collector, and that in preparing the slurry for the functional layer, ⁇ -Al 2 O 3 powder, a binder, and acrylic resin particles having an average particle size (D50) of 8.0 ⁇ m were mixed in a solid mass ratio of 65.6:21.8:12.6.
  • D50 average particle size
  • the difference between the average particle size (D50) of the acrylic resin particles and the average thickness (Db) of the heat-resistant layer was 5 ⁇ m.
  • the ten-point average roughness (Rz) of the outer surface of the functional layer was measured and found to be 7.8 ⁇ m.
  • Table 2 summarizes the evaluation of the occurrence of buckling of the electrode body and the results of the battery resistance in Comparative Examples 9 and 10, and Examples 1 to 4. However, the battery resistance values are shown as relative values for Comparative Examples 9, 10, and Examples 1 to 4, with the result of Comparative Example 1 set as the standard (100).
  • ⁇ Comparative Example 12> A secondary battery was produced in the same manner as in Comparative Example 1, except that an aluminum foil having a thickness of 15.0 ⁇ m and a 1% elongation yield strength of 58 MPa was used for the positive electrode current collector, and the same functional layer slurry as in Comparative Example 10 was used, and the same test was performed.
  • Example 5 A secondary battery was produced in the same manner as in Comparative Example 1, except that an aluminum foil having a thickness of 15.0 ⁇ m and a 1% elongation yield strength of 58 MPa was used for the positive electrode current collector, and the same functional layer slurry as in Example 1 was used, and the same test was performed.
  • Example 6 A secondary battery was produced in the same manner as in Comparative Example 1, except that an aluminum foil having a thickness of 15.0 ⁇ m and a 1% elongation yield strength of 58 MPa was used for the positive electrode current collector, and the same functional layer slurry as in Example 2 was used, and the same tests were performed.
  • Example 7 A secondary battery was produced in the same manner as in Comparative Example 1, except that an aluminum foil having a thickness of 15.0 ⁇ m and a 1% elongation yield strength of 58 MPa was used for the positive electrode current collector, and the same functional layer slurry as in Example 3 was used, and the same tests were performed.
  • Example 8 A secondary battery was produced in the same manner as in Comparative Example 1, except that an aluminum foil having a thickness of 15.0 ⁇ m and a 1% elongation yield strength of 58 MPa was used for the positive electrode current collector, and the same functional layer slurry as in Example 4 was used, and the same tests were performed.
  • Example 9 A secondary battery was produced in the same manner as in Comparative Example 1, and the same tests were performed, except that an aluminum foil having a thickness of 15.0 ⁇ m and a 1% elongation yield strength of 58 MPa was used for the positive electrode current collector, a copper foil having a thickness of 7.8 ⁇ m and a 1% elongation yield strength of 200 MPa was used for the negative electrode current collector, and the same functional layer slurry as in Example 4 was used.
  • Table 3 summarizes the evaluation of the occurrence of buckling of the electrode body and the results of the battery resistance in Comparative Examples 11 and 12, and Examples 5 to 9. However, the battery resistance values are shown as relative values for Comparative Examples 11 and 12, and Examples 5 to 9, with the result of Comparative Example 1 set as the standard (100).
  • Example 9 in which both the positive electrode current collector and the negative electrode current collector satisfied the relationship CM ⁇ CT ⁇ 1700 and the separator surface (the outer surface of the functional layer) had a ten-point average roughness (Rz) of 2.7 ⁇ m or more, buckling of the electrode body did not occur and an increase in battery resistance was also suppressed.
  • An electrode assembly including a positive electrode, a negative electrode, and a separator provided between the positive electrode and the negative electrode;
  • the positive electrode has a positive electrode current collector and a positive electrode mixture layer disposed on the positive electrode current collector
  • the negative electrode has a negative electrode current collector and a negative electrode mixture layer disposed on the negative electrode current collector
  • the negative electrode mixture layer has a negative electrode active material including a Si-containing material
  • At least one of the positive electrode current collector and the negative electrode current collector has a 1% elongation yield strength CM (MPa) and an average thickness CT ( ⁇ m) of the current collector that satisfy the relationship CM ⁇ CT ⁇ 1700
  • the separator has a first separator surface facing the positive electrode and a second separator surface facing the negative electrode, and at least one of the first separator surface and the second separator surface has a ten-point average roughness (Rz) of 2.7 ⁇ m or more.
  • the separator includes a substrate having a first surface and a second surface opposite to the first surface, and a functional layer disposed on at least the first surface of the first surface and the second surface of the substrate;
  • the secondary battery according to any one of (1) to (3), wherein an outer surface of the functional layer is a surface of the first separator facing the positive electrode or a surface of the second separator facing the negative electrode, and has a ten-point average roughness (Rz) of 0.7 ⁇ m or more.
  • Rz ten-point average roughness
  • the functional layer includes a heat-resistant layer containing inorganic particles and resin particles dispersed in the heat-resistant layer
  • the resin particles have an area occupancy of 2% or more and 30% or less when viewed from above on the surface of the functional layer.
  • the heat-resistant layer contains a binder and a polymer having aramid bonds, and a content of the inorganic particles is 25 mass% or more and 900 mass% or less with respect to a total mass of the binder and the polymer having aramid bonds.
  • the separator includes a substrate having a first surface and a second surface opposite to the first surface, and a functional layer disposed on the first surface of the substrate;
  • the secondary battery according to any one of (1) to (11), wherein the second surface of the substrate is the first separator surface facing the positive electrode or the second separator surface facing the negative electrode, and has a ten-point average roughness (Rz) of 2.7 ⁇ m or more.

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  • Chemical & Material Sciences (AREA)
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  • Electrochemistry (AREA)
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  • Engineering & Computer Science (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Composite Materials (AREA)
  • Manufacturing & Machinery (AREA)
  • Secondary Cells (AREA)
  • Battery Electrode And Active Subsutance (AREA)
PCT/JP2023/040382 2022-11-22 2023-11-09 二次電池 Ceased WO2024111423A1 (ja)

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JP2010171005A (ja) * 2008-12-24 2010-08-05 Mitsubishi Plastics Inc 電池用セパレータおよび非水系リチウム二次電池
JP2014089916A (ja) * 2012-10-31 2014-05-15 Tdk Corp リチウムイオン二次電池用集電体、およびそれを用いたリチウムイオン二次電池
JP2015167109A (ja) * 2014-03-04 2015-09-24 株式会社豊田自動織機 蓄電装置
WO2016035290A1 (ja) 2014-09-03 2016-03-10 三洋電機株式会社 非水電解質二次電池用負極活物質及び非水電解質二次電池

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JP5994354B2 (ja) * 2011-09-05 2016-09-21 ソニー株式会社 セパレータおよび非水電解質電池、並びに、電池パック、電子機器、電動車両、蓄電装置および電力システム
KR101577383B1 (ko) * 2012-07-30 2015-12-14 데이진 가부시키가이샤 비수 전해질 전지용 세퍼레이터 및 비수 전해질 전지
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JP2010171005A (ja) * 2008-12-24 2010-08-05 Mitsubishi Plastics Inc 電池用セパレータおよび非水系リチウム二次電池
JP2014089916A (ja) * 2012-10-31 2014-05-15 Tdk Corp リチウムイオン二次電池用集電体、およびそれを用いたリチウムイオン二次電池
JP2015167109A (ja) * 2014-03-04 2015-09-24 株式会社豊田自動織機 蓄電装置
WO2016035290A1 (ja) 2014-09-03 2016-03-10 三洋電機株式会社 非水電解質二次電池用負極活物質及び非水電解質二次電池

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