WO2026029029A1 - Mélange d'électrode négative pour batterie secondaire, électrode négative et batterie secondaire - Google Patents

Mélange d'électrode négative pour batterie secondaire, électrode négative et batterie secondaire

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Publication number
WO2026029029A1
WO2026029029A1 PCT/JP2025/026772 JP2025026772W WO2026029029A1 WO 2026029029 A1 WO2026029029 A1 WO 2026029029A1 JP 2025026772 W JP2025026772 W JP 2025026772W WO 2026029029 A1 WO2026029029 A1 WO 2026029029A1
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WIPO (PCT)
Prior art keywords
negative electrode
electrode mixture
silicon
mass
total mass
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English (en)
Japanese (ja)
Inventor
豊崇 中江
拡哲 鈴木
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Panasonic Intellectual Property Management Co Ltd
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Panasonic Intellectual Property Management Co Ltd
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Publication of WO2026029029A1 publication Critical patent/WO2026029029A1/fr
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Anticipated expiration legal-status Critical

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers

Definitions

  • This disclosure relates to a negative electrode mixture for a secondary battery, a negative electrode, and a secondary battery, and in particular to reducing the resistance and improving the capacity retention rate of a secondary battery.
  • Patent Document 1 describes a secondary battery negative electrode in which the negative electrode mixture layer contains a negative electrode active material and ion exchange particles that adsorb transition metal ions and release specific cations, and the ion exchange particles contain at least one of gold and platinum. Patent Document 1 also describes the use of zeolite, kaolinite, halloysite, illite, and montmorillonite as examples of ion exchange particles.
  • the negative electrode active material in the negative electrode mixture contains a silicon-containing material
  • the negative electrode active material does not contain a silicon-containing material. Therefore, there is little need to improve the squeezing out of liquid during charging and discharging.
  • a negative electrode mixture for a secondary battery comprises a negative electrode active material and a hollow columnar material as an additive, the negative electrode active material containing a silicon-containing material, the hollow columnar material having pores with a diameter of 1 nm or more, and where L is the length of the hollow columnar material in the major axis direction and D is the diameter of the pore, the ratio L/D is L/D>5.
  • a negative electrode for a secondary battery includes a negative electrode current collector and a negative electrode mixture layer formed on the negative electrode current collector.
  • the negative electrode mixture layer contains a negative electrode mixture, and the negative electrode mixture is the negative electrode mixture of the present disclosure.
  • a secondary battery according to one embodiment of the present disclosure comprises an electrode group having a positive electrode and a negative electrode, and a non-aqueous electrolyte, and the negative electrode is the negative electrode according to the present disclosure.
  • the negative electrode active material in the negative electrode mixture contains a silicon-containing material
  • the negative electrode mixture contains hollow columnar materials as additives.
  • the hollow columnar materials have pores with diameters of 1 nm or more, and the ratio L/D is L/D > 5, where L is the length along the major axis of the hollow columnar materials and D is the diameter of the pores.
  • FIG. 1 is a perspective view of a secondary battery according to an embodiment
  • 2 is a schematic partial cross-sectional view of the secondary battery of the embodiment, taken along a cross section passing through the negative electrode tab and including a direction parallel to the thickness direction of the electrode body and the winding axis direction.
  • FIG. 1 is a cross-sectional view showing only one side portion in a thickness direction of a negative electrode constituting a secondary battery of an embodiment.
  • FIG. 4 is a schematic diagram of halloysite, which is a hollow columnar substance contained in the negative electrode mixture layer of the negative electrode shown in FIG. 3.
  • FIG. 4 is a cross-sectional view of a main part of a secondary battery according to another embodiment of the present invention.
  • the negative electrode active material contains a silicon-containing material
  • the inventors discovered that this issue can be resolved by including hollow columnar materials as additives in the negative electrode mixture and regulating the dimensions and shape of the hollow columnar materials.
  • the hollow columnar materials added to the negative electrode mixture have pores with a diameter of 1 nm or more, and the ratio L/D is set to L/D > 5, where L is the length of the hollow columnar material in the longitudinal direction and D is the diameter of the pores. This reduces the resistance of the secondary battery and improves the capacity retention during charge-discharge cycles when the silicon-containing material is present in a large amount in the negative electrode mixture.
  • a lithium-ion secondary battery which is a secondary battery and a non-aqueous electrolyte secondary battery according to the present disclosure
  • examples are given of a secondary battery in which a wound electrode body is housed in an exterior body made of a laminate sheet including a metal layer and a resin layer
  • a secondary battery in which a stacked electrode body is housed in the exterior body instead of the wound electrode body may also be a cylindrical battery housed in a cylindrical battery case, and the battery case may be prismatic, coin-shaped, etc.
  • Fig. 1 is a perspective view showing the general shape of a secondary battery 10 according to an embodiment.
  • Fig. 2 is a schematic partial cross-sectional view of secondary battery 10 taken along a plane that passes through negative electrode tab 24 and includes a direction parallel to the thickness direction of the electrode body and the direction of winding axis O1.
  • the secondary battery 10 has a thin rectangular parallelepiped shape overall, and includes an electrode body 60 and an exterior body 12 that houses the electrode body 60 and a non-aqueous electrolyte.
  • the exterior body 12 is a laminate sheet exterior body, formed by folding a film-like laminate sheet 11 containing an adhesive resin layer in half along the bottom portion 17, and a wound electrode body 60 is housed in a thick, rectangular storage portion 13.
  • the laminate sheet 11 is a metal layer made of, for example, aluminum or an aluminum alloy, with an inner resin layer, an adhesive resin layer, provided on the surface that will be on the inside when the laminate sheet 11 is folded in half and stacked.
  • the inner resin layer is made of, for example, polypropylene.
  • the metal layer and inner resin layer can be adhered together using, for example, carboxylic acid-modified polypropylene, in which carboxyl groups are added to polypropylene.
  • the electrode body 60 is then wrapped in the folded laminate sheet 11, and the remaining three sides of the laminate sheet 11 are sealed.
  • the exterior body 12 has a top portion 16 on the upper side, a bottom portion 17 on the lower side, a first side portion 18 on the left side, and a second side portion 20 on the right side.
  • the top portion 16 and the first and second side portions 18, 20 are each portions where the laminate sheet 11 is overlapped, and a sealing portion is formed in each.
  • the first and second side portions 18, 20 are overlapped on the side walls of the storage portion 13 by folding the laminate sheet 11 in the thickness direction.
  • the bottom portion 17 is the folded portion of the laminate sheet 11 in the exterior body 12.
  • the top portion 16 is overlapped at both longitudinal ends at the overlapping portion of the outer periphery of the folded laminate sheet 11, with the positive electrode tab 22 and negative electrode tab 24 extending out.
  • the positive electrode tab 22 and negative electrode tab 24 are connected to the positive electrode and negative electrode of the electrode body 60, respectively.
  • Molten resins 26, 28 are welded to the base portions of the positive electrode tab 22 and negative electrode tab 24.
  • a secondary battery 10 equipped with such an exterior body 12 is electrically connected to an external load via the positive electrode tab 22 and the negative electrode tab 24.
  • the opposing portions of the folded laminate sheet 11 are overlapped with the inner resin layers in contact and welded together by heat and pressure.
  • the housing portion 13 is provided in the exterior body 12, inside the overlapping portion of the folded laminate sheet 11, and houses the electrode body 60.
  • the electrode body 60 is formed by winding a strip-shaped positive electrode 30 and a strip-shaped negative electrode 40 with a separator 70 interposed between them. At this time, molten resins 26, 28 are welded to the positive electrode tab 22 and the negative electrode tab 24, respectively. Next, the positive electrode tab 22 is welded to the exposed portion of the metal positive electrode core that forms the positive electrode 30, and the negative electrode tab 24 is welded to the exposed portion of the metal negative electrode core that forms the negative electrode 40.
  • a positive electrode mixture layer is formed on both sides of the positive electrode core, and a negative electrode mixture layer is formed on both sides of the negative electrode core.
  • the positive electrode core is made of, for example, aluminum foil, and the negative electrode core is made of, for example, copper foil.
  • the positive electrode mixture layer contains a positive electrode active material such as a lithium transition metal composite oxide.
  • the negative electrode mixture layer contains a negative electrode active material and a hollow columnar material as an additive.
  • the negative electrode active material contains at least a silicon-containing material.
  • the following provides a detailed description of the positive electrode 30, negative electrode 40, separator 70, and non-aqueous electrolyte that make up the secondary battery 10, particularly the negative electrode mixture layer that makes up the negative electrode 40, and the negative electrode mixture that forms the negative electrode mixture layer.
  • the positive electrode 30 includes a positive electrode current collector and a positive electrode mixture layer formed on both sides of the positive electrode current collector.
  • the positive electrode current collector can be a foil of a metal, such as aluminum or an aluminum alloy, that is stable within the potential range of the positive electrode, or a film with such a metal disposed on the surface.
  • the positive electrode mixture layer includes, for example, a positive electrode active material, a binder, and a conductive material. While the positive electrode mixture layer can be formed on only one side of the positive electrode current collector, it is preferable that it be formed on both sides of the positive electrode current collector.
  • the positive electrode 30 can be manufactured, for example, by applying a slurry of a positive electrode mixture containing a positive electrode active material, a binder, a conductive material, etc., onto the positive electrode current collector, drying and rolling the coating, and forming a positive electrode mixture layer on both sides of the positive electrode current collector.
  • the positive electrode active material contained in the positive electrode mixture layer is composed primarily of a lithium-containing metal composite oxide.
  • metal elements contained in the lithium-containing metal composite oxide include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, W, Ca, Sb, Pb, Bi, and Ge.
  • An example of a suitable lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.
  • Examples of conductive materials contained in the positive electrode mixture layer include carbon materials such as carbon black, acetylene black, ketjen black, graphite, and carbon nanotubes.
  • Examples of binders contained in the positive electrode mixture layer include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide, acrylic resin, and polyolefin. These resins may also be used in combination with carboxymethyl cellulose (CMC) or its salts, polyethylene oxide (PEO), and the like.
  • FIG. 3 is a cross-sectional view showing only one thickness-wise side portion of a negative electrode constituting a secondary battery 10.
  • the negative electrode 40 includes a negative electrode current collector 41 and a negative electrode mixture layer 42 formed on the negative electrode current collector 41, i.e., on both sides of the negative electrode current collector 41.
  • the negative electrode mixture layer formed on the other thickness-wise side (the lower side in FIG. 3) is omitted.
  • the negative electrode current collector 41 can be a foil of a metal, such as copper or a copper alloy, that is stable within the potential range of the negative electrode, or a film having such a metal disposed on its surface.
  • the negative electrode 40 can be manufactured by applying a slurry of a negative electrode mixture containing a negative electrode active material, hollow columnar materials 43, and a binder onto a negative electrode current collector 41, drying and rolling the coating, and forming, for example, a negative electrode mixture layer 42 on both sides of the negative electrode current collector 41.
  • At least a silicon-containing material is used as the negative electrode active material contained in the negative electrode mixture that forms the negative electrode mixture layer 42.
  • the negative electrode active material may also contain a carbon material such as graphite in addition to the silicon-containing material.
  • carbon materials that function as negative electrode active materials include natural graphite such as flake graphite, lump graphite, and amorphous graphite, artificial graphite such as lump artificial graphite and graphitized mesophase carbon microbeads, and mixtures of these.
  • the silicon-containing material may be any material that contains Si, and examples include silicon alloys, silicon compounds, and composite materials containing Si. Of these, composite materials containing Si are preferred. One type of silicon-containing material may be used alone, or two or more types may be used in combination.
  • a suitable silicon-containing material is a composite particle containing an ion-conducting phase and a silicon phase dispersed in the ion-conducting phase.
  • the ion-conducting phase is, for example, at least one selected from the group consisting of a silicate phase, a carbon phase, a silicide phase, and a silicon oxide phase.
  • the silicide phase is a compound phase consisting of Si and an element more electropositive than Si, and examples include NiSi, Mg2Si , and TiSi2 .
  • the silicon phase is formed by dispersing Si in the form of fine particles.
  • the ion-conducting phase is a continuous phase composed of a collection of particles finer than the silicon phase.
  • the ratio of the total mass of the silicon layer to the total mass of the silicon-containing material is preferably 30% by mass or more and 60% by mass or less.
  • the composite material may have a conductive layer covering the surface of the ion-conducting phase.
  • the conductive layer is made of a material with higher conductivity than the ion-conducting layer and forms a good conductive path within the negative electrode mixture layer 42.
  • the conductive layer is, for example, a carbon coating made of a conductive carbon material. Examples of conductive carbon materials that can be used include carbon black such as acetylene black and ketjen black, graphite, and amorphous carbon (amorphous carbon) with low crystallinity.
  • the thickness of the conductive layer is preferably 1 nm to 200 nm, or 5 nm to 100 nm, taking into consideration ensuring conductivity and the diffusibility of Li ions into the particles. The thickness of the conductive layer can be measured by observing the cross section of the composite material using a SEM or transmission electron microscope (TEM).
  • the ion-conducting phase may contain at least one element selected from the group consisting of Group 1 and Group 2 elements of the periodic table.
  • the ion-conducting layer may be a silicon oxide phase doped with Li.
  • the ion-conducting phase may also contain at least one element selected from the group consisting of B, Al, Zr, Nb, Ta, V, Y, Ti, P, Bi, Zn, Sn, Pb, Sb, Co, Er, F, W, and lanthanides.
  • An example of a suitable Si-containing composite material is a composite particle having a sea-island structure in which fine Si particles are substantially uniformly dispersed in an amorphous silicon oxide phase, and which is generally represented by the general formula SiO x (0 ⁇ x ⁇ 2).
  • the main component of the silicon oxide may be silicon dioxide.
  • the silicon oxide phase may also be doped with Li.
  • the oxygen content ratio (x) to Si is, for example, 0.5 ⁇ x ⁇ 2.0, and preferably 0.8 ⁇ x ⁇ 1.5.
  • a suitable Si-containing composite material is composite particles having a sea-island structure in which fine Si particles are substantially uniformly dispersed in an amorphous silicate phase.
  • a suitable silicate phase is a lithium silicate phase containing Li.
  • a suitable composite material containing Si is a composite particle having a sea-island structure in which fine Si particles are dispersed approximately uniformly in a carbon phase.
  • the carbon phase is preferably an amorphous carbon phase.
  • the carbon phase may contain crystalline phase components, but it is preferable that the amorphous phase components predominate.
  • the amorphous carbon phase is composed of a carbon material in which the average interplanar spacing of the (002) planes measured by X-ray diffraction exceeds 0.34 nm, for example. Note that a composite material containing a carbon phase may or may not have a conductive layer separate from the carbon phase.
  • the ratio of the total mass of silicon contained in the silicon-containing material to the total mass of the negative electrode mixture be 10 mass% or more, as this increases the capacity retention rate of the battery capacity during charge/discharge cycles and reduces electrical resistance.
  • the ratio of the total mass of silicon contained in the silicon-containing material to the total mass of the negative electrode mixture is 30 mass % or more, in terms of increasing the capacity retention rate and reducing the electrical resistance.
  • the ratio of the total mass of silicon contained in the silicon-containing material to the total mass of the negative electrode mixture is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less. If the ratio of the total mass of silicon contained in the silicon-containing material to the total mass of the negative electrode mixture exceeds 50% by mass, the volume change of the negative electrode mixture during charging and discharging may become excessively large, and the diffusibility of the non-aqueous electrolyte within the electrode body may decrease.
  • the ratio of the total mass of silicon contained in the silicon-containing material to the total mass of the negative electrode mixture is preferably 10% by mass or more and 50% by mass or less, more preferably 30% by mass or more and 50% by mass or less, and even more preferably 30% by mass or more and 40% by mass or less.
  • Figure 4 is a schematic diagram of halloysite, which is a hollow columnar material 43 contained in the negative electrode mixture layer 42.
  • the halloysite is tubular and has pores 44 with diameters of 1 nm or more. If the length of the halloysite in the major axis direction is L and the diameter of the pores 44 is D, then the ratio L/D is L/D > 5.
  • L/D the ratio of the halloysite in the major axis direction
  • L/D is L/D > 5.
  • the hollow columnar material 43 is preferably a silicate compound such as halloysite.
  • Silicate compounds have a lithophilic property and high lithium diffusivity. This promotes the transport of lithium ions in the negative electrode 40, thereby further reducing the resistance of the secondary battery 10.
  • the content of the silicate compound, which is the hollow columnar material 43, relative to the total mass of the negative electrode mixture can be set to 1% by mass or more and 10% by mass or less. This allows for even lower resistance of the secondary battery 10.
  • the content of the silicate compound, which is the hollow columnar material 43, relative to the total mass of the negative electrode mixture be 1% by mass or more and 3% by mass or less, in terms of increasing the capacity retention rate and further reducing the resistance.
  • the discharge capacity per 1.0 g of the negative electrode mixture layer is 0.60 Ah or more in terms of increasing the capacity retention rate and reducing resistance.
  • a porous sheet having ion permeability and insulating properties is used for the separator 70.
  • the porous sheet include a microporous thin film, a woven fabric, and a nonwoven fabric.
  • Suitable materials for the separator 70 include polyolefins such as polyethylene and polypropylene, and cellulose.
  • the separator 70 may have a single-layer structure or a multi-layer structure.
  • a highly heat-resistant resin layer such as an aramid resin may be formed on the surface of the separator 70.
  • a filler layer containing an inorganic filler may be formed at the interface between the separator 70 and at least one of the positive electrode 30 and the negative electrode 40.
  • inorganic fillers include oxides containing metal elements such as Ti, Al, Si, and Mg, and phosphate compounds.
  • the filler layer can be formed by applying a slurry containing the filler to the surface of the positive electrode 30, the negative electrode 40, or the separator 70.
  • binders contained in the negative electrode mixture layer 42 include styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR), 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.
  • SBR styrene butadiene rubber
  • NBR nitrile butadiene rubber
  • CMC carboxymethyl cellulose
  • PAA polyacrylic acid
  • PAA-Na polyacrylic acid
  • PAA-K polyvinyl alcohol
  • PVA polyvinyl alcohol
  • the non-aqueous electrolyte has ion conductivity (e.g., lithium ion conductivity).
  • the non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.
  • the non-aqueous electrolyte is not limited to a liquid electrolyte (nonaqueous electrolyte solution) and may be a solid electrolyte using a gel-like polymer or the like.
  • lithium salts such as LiBF4 and LiPF6 are used as the electrolyte salt.
  • esters such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and methyl propionate (MP), ethers, nitriles, amides, and mixed solvents of two or more of these are used.
  • the non-aqueous solvent may contain a halogen-substituted compound in which at least a portion of the hydrogen atoms of these solvents are replaced with halogen atoms such as fluorine.
  • halogen-substituted compounds include fluorinated cyclic carbonates such as fluoroethylene carbonate (FEC), fluorinated chain carbonates, and fluorinated chain carboxylic acid esters such as methyl fluoropropionate (FMP).
  • FEC fluoroethylene carbonate
  • FMP fluorinated chain carboxylic acid esters
  • the non-aqueous electrolyte preferably contains 5% by mass or more of FEC, and more preferably 5% by mass or more and 15% by mass or less of FEC, based on the mass of the non-aqueous electrolyte.
  • the solid electrolyte for example, a solid or gel-like polymer electrolyte, an inorganic solid electrolyte, etc. is used.
  • 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 the non-aqueous solvent and gels is used.
  • the polymer material for example, fluororesin, acrylic resin, polyether resin, etc. is used.
  • the inorganic solid electrolyte for example, a material known in all-solid-state lithium-ion secondary batteries (for example, oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.) is used.
  • a material known in all-solid-state lithium-ion secondary batteries for example, oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.
  • the negative electrode active material in the negative electrode mixture contains a silicon-containing material
  • the negative electrode mixture contains hollow columnar materials 43 as an additive.
  • the hollow columnar materials 43 have pores with diameters of 1 nm or more, and when the length of the hollow columnar materials 43 in the longitudinal direction is L and the diameter of the pores is D, the ratio L/D is L/D > 5. This allows the hollow columnar materials 43 to retain the electrolyte despite large expansion and contraction during charge and discharge, thereby suppressing squeezing of the electrolyte due to charge and discharge.
  • the resistance of the secondary battery 10 can be reduced, and the capacity retention rate during charge and discharge cycles when the silicon-containing material is present in a large amount in the negative electrode mixture can be improved.
  • the hollow columnar material 43 is a silicate compound, the resistance of the secondary battery 10 can be further reduced.
  • the negative electrode active material does not contain a silicon-containing material, and at least one of gold and platinum is present in the ion exchange particles, and metal ions other than Li ions are adsorbed.
  • the ion exchange particles do not contribute to improving the conductivity of Li ions, and it is thought that there is a high possibility that adding ion exchange particles to the negative electrode mixture will lead to an increase in the resistance of the secondary battery.
  • FIG. 5 is a cross-sectional view of a key portion of a secondary battery 10a according to another embodiment.
  • the secondary battery 10a of this example is a stacked secondary battery having an electrode assembly 60a formed by stacking a positive electrode 30a and a negative electrode 40a with a separator 70a interposed therebetween, and an exterior body 72.
  • the exterior body 72 contains the electrode assembly 60a and a non-aqueous electrolyte, and has openings (not shown) at both ends in a first direction (the left-right direction in Figure 5) perpendicular to the stacking direction of the electrode assembly 60a.
  • the exterior body 72 is made by folding a laminate sheet in half, which includes a metal layer and an adhesive resin layer provided on the inner surface of the metal layer, and the overlapping portion around the electrode assembly 60a is sealed by adhesive.
  • the positive electrode tab 76 connected to the positive electrode 30a extends from one opening of the exterior body 72 to the outside of the secondary battery 10a
  • the negative electrode tab 75 connected to the negative electrode 40a extends from the other opening of the exterior body 72 to the outside of the secondary battery 10a.
  • a first gasket (not shown) welded to the inner surface of the opening is interposed between the exterior body 72 and the positive electrode tab 76, sealing the opening.
  • a second gasket (not shown) welded to the inner surface of the opening is interposed between the exterior body 72 and the negative electrode tab 75, sealing the opening.
  • a gasket may not be used for the opening, and a laminate sheet may be directly welded to the periphery of the opening, sandwiching the tabs 75, 76.
  • the positive electrode 30a, negative electrode 40a, and separator 70a are each rectangular, with the negative electrode 40a being slightly larger than the positive electrode 30a.
  • the materials of the positive electrode 30a, negative electrode 40a, and separator 70a are the same as those in the configurations shown in Figures 1 to 4.
  • the negative electrode mixture layer 42a constituting the negative electrode 40a is formed from a negative electrode mixture containing a negative electrode active material and a hollow columnar material that is a silicate compound as an additive.
  • the negative electrode active material contains at least a silicon-containing material. This, like the configurations shown in Figures 1 to 4, reduces the resistance of the secondary battery 10a and improves the capacity retention rate during charge-discharge cycles when the silicon-containing material content in the negative electrode mixture is high.
  • the other configurations and functions are the same as those shown in Figures 1 to 4.
  • Example 1 [Positive electrode] A lithium transition metal oxide represented by LiNi0.9Co0.05Al0.05O2 ( NCA ) was used as the positive electrode active material. 100 parts by mass of the positive electrode active material, 0.4 parts by mass of carbon nanotubes (CNT), and 0.6 parts by mass of polyvinylidene fluoride (PVDF) were mixed to prepare a positive electrode mixture layer slurry. Next, the positive electrode mixture layer slurry was applied to the aluminum foil positive electrode current collector 31a, leaving the portion where the positive electrode tab 76 was connected, and the coating was dried. The coating was rolled using a roller and then cut to a predetermined electrode size having a 20 mm square positive electrode mixture layer. A positive electrode 30a was fabricated in which a positive electrode mixture layer 32a was formed on one side of the positive electrode current collector 31a.
  • NCA lithium transition metal oxide represented by LiNi0.9Co0.05Al0.05O2
  • the negative electrode active material was a silicon-containing material, a composite particle (Si-C) containing a carbon phase and a Si phase dispersed in the carbon phase, graphite (Gr), a lithium salt of polyacrylic acid (PAA), a sodium salt of carboxymethyl cellulose (CMC), a dispersion of styrene-butadiene copolymer (SBR), and halloysite, a hollow columnar material, as an additive. These were mixed in a solids mass ratio of X:(100-X):1:1:5:Y, and an appropriate amount of water was added to prepare a negative electrode mixture layer slurry.
  • Example 1 In Example 1, X was determined so that the ratio of the total mass of silicon element in the silicon-containing material to the total mass of the negative electrode mixture was 20% by mass. Y was determined so that the ratio of the halloysite content to the total mass of the negative electrode mixture was 1% by mass.
  • the negative electrode mixture layer slurry was applied to one surface of the negative electrode current collector 41a made of copper foil, leaving only the area where the negative electrode tab 75 was connected, and the coating was dried to form the negative electrode mixture layer 42a on one surface of the negative electrode current collector 41a.
  • the coating was then rolled using a roller and cut to the specified electrode size, producing the negative electrode 40a in which the negative electrode mixture layer 42a was formed on one surface of the negative electrode current collector 41a.
  • Non-aqueous electrolyte A non-aqueous electrolyte was prepared by adding 4 mass% of vinylene carbonate (VC) to a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:7, and dissolving LiPF6 at a ratio of 1.4 mol/L.
  • VC vinylene carbonate
  • EMC ethyl methyl carbonate
  • a negative electrode tab 75 and a positive electrode tab 76 were attached to the negative electrode 40a and the positive electrode 30a, respectively, and the negative electrodes 40 and the positive electrodes 30a were stacked with a separator 70a interposed therebetween to prepare an electrode assembly 60a.
  • a three-layer polypropylene separator was used as the separator 70a.
  • the prepared electrode assembly 60a was inserted into an exterior body made of an aluminum laminate sheet, and the opening of the exterior body was sealed to prepare a test cell (laminate cell).
  • Example 2 X in Example 1 was determined so that the ratio of the total mass of silicon element in the silicon-containing material to the total mass of the negative electrode mixture was 10 mass %.
  • the other conditions of Example 2 were the same as those of Example 1.
  • Example 3 In preparing the negative electrode mixture slurry, X in Example 1 was determined so that the ratio of the total mass of silicon element in the silicon-containing material to the total mass of the negative electrode mixture was 30 mass%.
  • Example 4 In preparing the negative electrode mixture slurry, X in Example 1 was determined so that the ratio of the total mass of silicon element in the silicon-containing material to the total mass of the negative electrode mixture was 40 mass%.
  • Example 5 In preparing the negative electrode mixture slurry, X in Example 1 was determined so that the ratio of the total mass of silicon element in the silicon-containing material to the total mass of the negative electrode mixture was 50 mass%.
  • Example 6 In preparing the negative electrode mixture slurry, Y in Example 1 was determined so that the proportion of the halloysite content relative to the total mass of the negative electrode mixture was 10 mass %.
  • Example 7 In preparing the negative electrode mixture slurry, Y in Example 1 was determined so that the proportion of the halloysite content relative to the total mass of the negative electrode mixture was 5 mass%.
  • Example 8 In preparing the negative electrode mixture slurry, Y in Example 1 was determined so that the proportion of the halloysite content relative to the total mass of the negative electrode mixture was 3 mass%.
  • Y in Example 1 was set to 0%. That is, in Comparative Example 1, the negative electrode mixture did not contain halloysite. The other conditions of Comparative Example 1 were the same as those of Example 1.
  • X in Example 1 was determined so that the ratio of the total mass of silicon element in the silicon-containing material to the total mass of the negative electrode mixture was 8 mass%. Furthermore, Y in Example 1 was set to 0%. That is, in Comparative Example 2, similar to Comparative Example 1, the negative electrode mixture did not contain halloysite. Other conditions in Comparative Example 2 were the same as those in Example 1.
  • X in Example 1 was determined so that the ratio of the total mass of silicon element in the silicon-containing material to the total mass of the negative electrode mixture was 8% by mass.
  • Y in Example 1 was set to 0%, but instead of halloysite, montmorillonite, a silicate compound that is not a hollow columnar substance but has a flat, layered structure, was added as an additive. At this time, the ratio of the montmorillonite content to the total mass of the negative electrode mixture was set to 1% by mass.
  • the other conditions of Comparative Example 3 were the same as those of Example 1.
  • Comparative Example 4 In preparing the negative electrode mixture slurry, X in Example 1 was set to 0. That is, in Comparative Example 4, no silicon-containing material was contained in the negative electrode mixture. The other conditions of Comparative Example 4 were the same as those of Example 1.
  • Comparative Example 5 In preparing the negative electrode mixture slurry, Y in Example 1 was set to 0%, but instead of halloysite, zeolite, which is a hollow material but not a hollow columnar material, was added as an additive. At this time, the content of zeolite relative to the total mass of the negative electrode mixture was set to 1 mass%. The other conditions of Comparative Example 5 were the same as those of Example 1.
  • Table 1 shows the ratio of the total mass of silicon element in the silicon-containing material to the total mass of the negative electrode mixture in the test cells of Examples 1-8 and Comparative Examples 1-5, and the ratio of the halloysite content to the total mass of the negative electrode mixture, expressed in mass percent.
  • Table 1 above shows the test results for the capacity retention rate and cell resistance (electrical resistance value) of the test cells of Examples 1-8 and Comparative Examples 1-5.
  • the test result of Comparative Example 1 is used as the reference value, and the test results of the other test cells are shown as relative values to that reference value.
  • the negative electrode mixture contained halloysite but no silicon-containing material, so the capacity retention rate after 50 cycles was even lower than in Comparative Example 3, and the electrical resistance value was significantly higher than in Comparative Example 1.
  • Comparative Example 5 zeolite was included in the negative electrode mixture instead of halloysite. Zeolite is hollow, but it is not a hollow columnar material. As a result, in Comparative Example 5, the capacity retention rate after 50 cycles was higher than in Comparative Example 1, but the electrical resistance value was also higher.
  • Examples 1-8 halloysite was contained in the negative electrode mixture, and thus electrical resistance was reduced, regardless of whether the negative electrode active material contained a silicon-containing material. Furthermore, the results of Examples 1-5 confirmed that the higher the total mass of silicon element in the silicon-containing material, the higher the capacity retention rate and the lower the electrical resistance rate. Furthermore, a comparison of the test results of Examples 1, 6-8 with the test results of Comparative Example 1 confirmed that electrical resistance was reduced when the silicate compound content was 1% by mass or more and 10% by mass or less relative to the total mass of the negative electrode mixture.
  • Configuration 1 A negative electrode mixture for a secondary battery, comprising: a negative electrode active material and a hollow columnar material as an additive, the negative electrode active material comprises a silicon-containing material, the hollow columnar material has pores with a diameter of 1 nm or more, When the length of the hollow columnar material in the major axis direction is L and the diameter of the pore is D, the ratio L/D is L/D>5.
  • Configuration 2 The hollow pillar-shaped material is a silicate compound. 2. The negative electrode mixture according to claim 1.
  • Configuration 3 The content of the silicate compound relative to the total mass is 1 mass% or more and 10 mass% or less. 3.
  • Configuration 4 The content of the silicate compound relative to the total mass is 1% by mass or more and 3% by mass or less. 4.
  • Configuration 5 The ratio of the total mass of silicon contained in the silicon-containing material to the total mass is 10 mass% or more;
  • Configuration 6 The ratio of the total mass of silicon contained in the silicon-containing material to the total mass is 30 mass% or more; 6.
  • Configuration 7 The ratio of the total mass of silicon contained in the silicon-containing material to the total mass is 50 mass% or less; 7.
  • Configuration 8 The silicon-containing material comprises an ion-conducting phase and a silicon phase dispersed in the ion-conducting phase.
  • the negative electrode mixture according to any one of configurations 1 to 7.
  • Configuration 9 the ion-conducting phase is at least one selected from the group consisting of a silicate phase, a carbon phase, a silicide phase, and a silicon oxide phase; 9.
  • Configuration 10 The ratio of the total mass of the silicon phase to the total mass of the silicon-containing material is 30 mass% or more and 60 mass% or less;
  • Negative electrode mixture configuration 11 according to configuration 8 or 9 Contains neither gold nor platinum, The negative electrode mixture according to any one of configurations 1 to 10.
  • Configuration 12 a negative electrode current collector; and a negative electrode mixture layer formed on the negative electrode current collector, the negative electrode mixture layer is configured to contain a negative electrode mixture, The negative electrode mixture is the negative electrode mixture according to any one of configurations 1 to 11.
  • Negative electrode for secondary batteries Configuration 13: The battery includes an electrode group having a positive electrode and a negative electrode, and a non-aqueous electrolyte, The negative electrode is the negative electrode of aspect 12.
  • Configuration 14 The discharge capacity per 1.0 g of the negative electrode mixture layer is 0.60 Ah or more. 14. The secondary battery according to claim 13.
  • REFERENCE SIGNS LIST 10 10a Secondary battery, 11 Laminate sheet, 12 Exterior body, 13 Storage section, 16 Top section, 17 Bottom section, 18 First side section, 20 Second side section, 22 Positive electrode tab, 24 Negative electrode tab, 26, 28 Welding resin, 30, 30a Positive electrode, 31a Positive electrode current collector, 32a Positive electrode mixture layer, 40, 40a Negative electrode, 41, 41a Negative electrode current collector, 42, 42a Negative electrode mixture layer, 43 Hollow columnar material, 52 Holes, 60, 60a Electrode body, 70, 70a Separator, 72 Exterior body, 75 Negative electrode tab, 76 Positive electrode tab.

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Abstract

L'invention concerne un mélange d'électrode négative pour une batterie secondaire comprenant un matériau actif d'électrode négative et une substance colonnaire creuse (43) en tant qu'additif. Le matériau actif d'électrode négative comprend au moins un matériau contenant du silicium. La substance colonnaire creuse (43) a des pores ayant un diamètre supérieur ou égal à 1 nm. Lorsque la longueur de la substance colonnaire creuse (43) dans la direction de l'axe long est L et que le diamètre des pores est D, le rapport L/D est D est L/D > 5.
PCT/JP2025/026772 2024-07-31 2025-07-29 Mélange d'électrode négative pour batterie secondaire, électrode négative et batterie secondaire Pending WO2026029029A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008071757A (ja) * 2006-09-11 2008-03-27 Lg Chem Ltd 粘土鉱物を含む電極合剤及びこれを用いた電気化学セル
US20180034047A1 (en) * 2016-07-28 2018-02-01 Samsung Sdi Co., Ltd. Negative electrode for rechargeable lithium battery, and rechargeable lithium battery including same
CN118335981A (zh) * 2023-01-12 2024-07-12 宁德时代新能源科技股份有限公司 负极极片、电极组件、电池单体、电池及用电设备

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008071757A (ja) * 2006-09-11 2008-03-27 Lg Chem Ltd 粘土鉱物を含む電極合剤及びこれを用いた電気化学セル
US20180034047A1 (en) * 2016-07-28 2018-02-01 Samsung Sdi Co., Ltd. Negative electrode for rechargeable lithium battery, and rechargeable lithium battery including same
CN118335981A (zh) * 2023-01-12 2024-07-12 宁德时代新能源科技股份有限公司 负极极片、电极组件、电池单体、电池及用电设备

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