WO2023182341A1 - 非水電解質二次電池 - Google Patents

非水電解質二次電池 Download PDF

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Publication number
WO2023182341A1
WO2023182341A1 PCT/JP2023/011177 JP2023011177W WO2023182341A1 WO 2023182341 A1 WO2023182341 A1 WO 2023182341A1 JP 2023011177 W JP2023011177 W JP 2023011177W WO 2023182341 A1 WO2023182341 A1 WO 2023182341A1
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WIPO (PCT)
Prior art keywords
electrode
current collector
negative electrode
separator
secondary battery
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Ceased
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PCT/JP2023/011177
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English (en)
French (fr)
Japanese (ja)
Inventor
崇寛 高橋
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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 US18/849,697 priority Critical patent/US20250219154A1/en
Priority to JP2024509153A priority patent/JPWO2023182341A1/ja
Priority to EP23774936.1A priority patent/EP4503239A4/en
Priority to CN202380029319.4A priority patent/CN118922980A/zh
Publication of WO2023182341A1 publication Critical patent/WO2023182341A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • 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
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/533—Electrode connections inside a battery casing characterised by the shape of the leads or tabs
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present disclosure relates to a non-aqueous electrolyte secondary battery.
  • Patent Document 1 discloses a wound electrode body which is formed by forming a mixture layer on both sides of a band-shaped current collector and is wound in a spiral shape with a separator interposed between the band-shaped electrodes, and the above-mentioned wound electrode body.
  • the electrode has the above-mentioned joint in a range of one turn or more from the outer circumferential end of the current collector in the winding direction.
  • Patent Document 1 states, ⁇ In conventional non-aqueous electrolyte secondary batteries, the mixture layer is formed up to the vicinity of the outer peripheral end of the current collector in the winding direction, so that, for example, the battery can is crushed. When an abnormal situation such as this occurs, when the outer peripheral end of the negative electrode breaks through the separator, its tip comes into contact with the mixture layer of the adjacent positive electrode.As a result, the negative electrode and positive electrode are electrically connected to each other, and the internal There was a problem with the occurrence of short circuits.'' Patent Document 1 states, ⁇ By providing an exposed portion of the current collector in which a mixture layer is not formed over a range of one turn or more from the end in the winding direction of the electrode, the electrode breaks through the separator and the adjacent electrode To provide a non-aqueous electrolyte secondary battery that can prevent or effectively suppress the occurrence of internal short circuits by ensuring that the same electrodes come into contact with each other even when they come into contact with each other. There is.
  • a burnout can occur when an abnormal condition occurs in one or more of a plurality of batteries and the battery reaches a high temperature.
  • the internal pressure of the high-temperature battery reaches a predetermined value, the gas inside the battery is discharged to the outside via a predetermined safety valve to ensure safety.
  • batteries around the battery in which the abnormality has occurred are heated from the outside, and a large amount of heat is transmitted to the battery case, reducing the strength of the battery case. In that case, cracks may occur in the side wall of the battery case before the safety valve is activated. High-temperature gas may be discharged from the cracks in an unintended direction, leading to a risk of fire.
  • One aspect of the present disclosure includes a first electrode having a first current collector, a second electrode having a second current collector, and a separator interposed between the first electrode and the second electrode.
  • a battery case that accommodates the electrode group and the nonaqueous electrolyte, the first electrode and the second electrode are wound together with the separator interposed therebetween.
  • the outermost periphery of the first electrode is arranged outside the outermost periphery of the second electrode, and the end of the winding of the first electrode does not pass through the second electrode and does not pass through the separator.
  • the present invention relates to a non-aqueous electrolyte secondary battery, wherein the surplus portion is an end portion wrapped around the outer surface of the first electrode on the inner side, and the surplus portion is an exposed portion of the first current collector.
  • FIG. 1 is a longitudinal cross-sectional view of a non-aqueous electrolyte secondary battery according to an embodiment of the present disclosure.
  • 1 is a conceptual diagram showing a cross-sectional structure of a non-aqueous electrolyte secondary battery according to an embodiment of the present disclosure.
  • a non-aqueous electrolyte secondary battery includes an electrode group, a non-aqueous electrolyte, and a battery case.
  • the battery case houses the electrode group and the nonaqueous electrolyte.
  • a nonaqueous electrolyte secondary battery is a secondary battery equipped with a liquid, gel, or solid nonaqueous electrolyte, and includes lithium ion secondary batteries, lithium secondary batteries (lithium metal secondary batteries), and all-solid secondary batteries. Includes batteries, etc.
  • the electrode group includes a first electrode having a first current collector, a second electrode having a second current collector, and a separator interposed between the first electrode and the second electrode.
  • the second electrode is wound with a separator in between. That is, the electrode group is wound, for example, cylindrical.
  • the shape of the battery case may be any shape as long as it can efficiently accommodate the wound electrode group.
  • it may have a cylindrical shape, or it may have a track shape (the cross section has a short side and a long side). It may also be a shape in which the short side of a rectangle is changed to an outwardly convex arc shape.
  • the material constituting the battery case is not particularly limited, but the present invention is most effective when it contains a metal with high thermal conductivity.
  • the battery case may be a metal case or a metal can (exterior can).
  • the material of the battery case may be stainless steel (SUS), steel (SPCC, SPCE, etc.), or the like.
  • the first electrode includes at least a first current collector, and may include a first active material layer provided on the surface of the first current collector.
  • the first active material layer contains an electrode active material.
  • the second electrode may include at least a second current collector, and may include a second active material layer provided on the surface of the second current collector.
  • the second active material layer contains an electrode active material.
  • at least one of the first electrode and the second electrode has an active material layer.
  • the electrode active material develops capacity through a faradaic reaction.
  • Each active material layer may be a mixture layer containing an electrode active material and other components (such as a binder).
  • the negative electrode may include a negative electrode current collector and a negative electrode active material layer (or negative electrode mixture layer) provided on the surface of the negative electrode current collector.
  • the positive electrode includes a positive electrode current collector and a positive electrode active material layer (or positive electrode mixture layer) provided on the surface of the positive electrode current collector.
  • the first current collector is a negative electrode current collector. If the first electrode is a positive electrode, the first current collector is a positive electrode current collector.
  • Each current collector is in the form of a sheet, and for example, metal foil is used.
  • Each current collector has, for example, an elongated or band-like shape.
  • the first current collector desirably contains Cu. Copper has good thermal conductivity, so even when the battery is heated from the outside, the battery case is less likely to become locally hot. Therefore, the strength of the battery case is maintained and cracks are less likely to occur.
  • the first current collector containing Cu copper foil, copper alloy foil, etc. can be used.
  • the thickness of the first current collector containing Cu may be, for example, 4 ⁇ m to 12 ⁇ m.
  • the first current collector desirably contains at least one selected from the group consisting of Al, Ti, and stainless steel.
  • the first current collector aluminum foil, aluminum alloy foil, titanium foil, titanium alloy foil, stainless steel foil, etc. can be used.
  • the thickness of the first current collector may be, for example, 10 ⁇ m to 20 ⁇ m.
  • the first active material layer is a negative electrode active material layer. If the first electrode is a positive electrode, the first active material layer is a positive electrode active material layer.
  • the negative electrode active material layer and the positive electrode active material layer are provided on predetermined surfaces of one or both surfaces of the current collector. Note that the negative electrode does not need to have a negative electrode active material layer.
  • the positive electrode active material layer faces the negative electrode with a separator in between.
  • the outermost periphery of the first electrode is arranged outside the outermost periphery of the second electrode.
  • the first electrode is the electrode forming the outermost periphery of the electrode group.
  • the outermost outer surface of the first electrode may be in contact with the battery case.
  • the end of the winding of the first electrode is the end of the surplus portion that is wound around the outer surface of the first electrode on the inner side (one layer inside) without passing through the second electrode or the separator.
  • the first active material layer may or may not be provided on the outer surface of the first electrode around which the excess portion is wrapped. That is, at least part or all of the outer surface of the first electrode around which the excess portion is wrapped may be an exposed portion of the first current collector.
  • the surplus portion has the function of suppressing cracks in the battery case when the battery is heated from the outside. If the battery is abnormally heated from the outside, the battery case will become hot and the strength of the battery case will decrease. If there is no surplus, when the pressure inside the battery builds up, the side wall of the battery case may crack before the safety valve is activated.
  • the excess portion has a thermal diffusion effect that suppresses local heating of the battery case, and also serves as a physical barrier to prevent the occurrence of cracks.
  • the surplus portion has the function of suppressing the possibility of battery fire when a plurality of batteries are used in combination (for example, when a module in which a plurality of batteries are housed in close proximity is used).
  • a battery with a surplus portion is prevented from cracking the battery case, and gas is more easily discharged than the safety valve provided in the battery.
  • the melting point of the first current collector is 600°C or higher, and at a temperature that does not melt due to high-temperature gas generated in abnormal situations (e.g., 1000°C or higher). It is more desirable that In this case, the first current collector acts as a barrier, suppressing cracks in the battery case, and suppressing gas discharge in unintended directions that may occur due to cracks.
  • the surplus portion is wrapped around the outer surface of the inner first electrode without using the second electrode or the separator.
  • the excess portion directly contacts the outer surface of the inner first electrode.
  • 50% or more or 80% or more (for example, 90% or more) of the surplus portion may be wrapped around the outer surface of the inner first electrode without using the second electrode or the separator. That is, 50% or more or 80% or more (for example, 90% or more) of the surplus portion may be brought into direct contact with the outer surface of the inner first electrode. If the first active material layer is not provided on the outer surface of the first electrode around which the excess portion is wrapped, the excess portion will directly contact the exposed portion of the outer surface of the first current collector.
  • the separator itself is at least partially made of a combustible material. If the separator burns between the first electrode on the inner circumferential side and the surplus portion, the heat diffusion effect of the surplus portion cannot be sufficiently obtained. Furthermore, it is considered that buckling of the outermost peripheral portion of the electrode group is likely to occur due to deformation of the separator, generation of burnt residue, etc., which promotes the occurrence of internal short circuits. Therefore, it is desirable that 95% or more of the surplus portion be wrapped around the outer surface of the inner first electrode without using the second electrode or the separator.
  • the length L1 of the surplus portion along the circumferential direction is 50% or more of the length L along the circumferential direction of the first electrode at the outermost periphery. % or more is more desirable, and 100% or more is still more desirable.
  • the winding start end of the electrode group may be composed of only the negative electrode, or only the negative electrode and the separator.
  • one or more turns from the end of the electrode group at the beginning of winding may be composed of only the negative electrode, or only the negative electrode and the separator.
  • the part "one round from the end of the electrode group where it starts to be rolled up" will also be referred to as the "center part of the electrode group.”
  • the central part of the electrode group may be composed of a negative electrode current collector and a negative electrode part having a negative electrode active material layer on one or both sides thereof, or may be composed of a laminate of such a negative electrode part and a separator.
  • the negative electrode or negative electrode current collector is less likely to be the starting point of thermal runaway than the positive electrode, so by configuring the center of the electrode group with something other than the positive electrode, that is, the negative electrode (or negative electrode current collector) or separator, the center of the electrode group can be It is possible to provide a strong cylindrical part. A hollow space is formed inside the cylindrical part. Such a cylindrical portion can maintain its shape even at high temperatures. Therefore, in the event of an abnormality, the hollow space at the center of the electrode group becomes a passage for gas generated inside the battery, and the gas is discharged to the outside through the safety valve. As a result, it becomes easier to suppress the battery from burning out.
  • the diameter of the hollow inside the cylindrical part formed by the central part of the electrode group is preferably as large as possible from the viewpoint of enhancing its function as a passage for high-temperature gas, for example, it is preferably 1 mm or more, and may be 2 mm or more or 3 mm or more. However, if the diameter of the hollow is too large, the volumetric energy density of the battery will decrease, so the diameter of the hollow is preferably, for example, 8 mm or less, more preferably 6 mm or less. Note that the diameter of the hollow space is measured in one round from the winding start end of the electrode group, that is, in a state where the center of the electrode group is pressed toward the outside (the hollow inner wall of the electrode group). At this time, the diameter of the equivalent circle of the cross section perpendicular to the winding axis direction of the space formed inside the hollow may be taken as the diameter of the hollow.
  • FIG. 1 is a longitudinal cross-sectional view of a cylindrical non-aqueous electrolyte secondary battery 10 (hereinafter also simply referred to as "battery 10") according to a first embodiment of the present disclosure.
  • FIG. 2 is a conceptual diagram showing the cross-sectional structure of the battery 10.
  • the present disclosure is not limited to the following configuration.
  • the battery 10 includes an electrode group 18, a non-aqueous electrolyte (not shown), and a cylindrical battery case (metal can) 22 with a bottom that accommodates these.
  • a sealing body 11 is caulked and fixed to the opening of the battery case 22 via a gasket 21. As a result, the inside of the battery 10 is sealed.
  • the sealing body 11 includes an internal pressure-operated safety valve that cuts off current when the battery internal pressure rises excessively and opens if necessary. That is, the sealing body includes a valve body 12 having a thin wall portion, a metal plate 13, and an annular insulating member 14 interposed between the valve body 12 and the metal plate 13. The valve body 12 and the metal plate 13 are electrically connected to each other at their respective centers.
  • a positive electrode lead 15L led out from the positive electrode 15 is connected to the metal plate 13. Therefore, the valve body 12 functions as an external terminal of the positive electrode 15 and also functions as a safety valve. When the internal pressure of the battery increases, the connection between the valve body 12 and the metal plate 13 is broken, and the current is cut off. Furthermore, when the thin wall portion is ruptured, gas is released to the outside, ensuring safety.
  • a negative electrode lead 16L led out from the negative electrode 16 is connected to the bottom inner surface of the battery case 22.
  • An annular groove 22a is formed near the open end of the battery case 22.
  • a first insulating plate 23 is arranged between one end surface of the electrode group 18 and the annular groove 22a.
  • a second insulating plate 24 is arranged between the other end surface of the electrode group 18 and the bottom of the battery case 22.
  • the electrode group 18 is formed by winding a positive electrode 15 and a negative electrode 16 into a cylindrical shape with a separator 17 in between.
  • the outermost periphery of the electrode group 18 is formed by the winding end side of the negative electrode 16. That is, in the electrode group 18, the outermost periphery of the negative electrode 16 is arranged outside the outermost periphery of the positive electrode 15.
  • FIG. 2 is a cross-sectional view of a part of the electrode group 18 (the outermost periphery (S)) closest to the side wall of the metal case. At the outermost periphery of the electrode group 18, the negative electrode current collector 16b on the winding end side is arranged. The outermost outer surface of the negative electrode 16 may be in contact with the inner surface of the side wall of the battery case 22.
  • the end of the winding of the negative electrode 16 is also the end of a surplus portion 16D that is wound around the outer surface of the negative electrode 16 on the inner side without passing through the positive electrode 15.
  • the surplus portion 16D is directly wrapped around the outer surface of the inner negative electrode 16 (negative electrode current collector 16b) without using the positive electrode 15 or the separator 17.
  • a negative electrode active material layer 16a is provided on the inner surface of the negative electrode 16 on the inner side of the circumference adjacent to the surplus portion 16D, but a negative electrode current collector 16b is exposed on the outer surface. This is because even if the negative electrode active material layer 16a is provided in the portion facing the surplus portion 16D, it does not contribute to the capacity.
  • a negative electrode active material layer 16a is provided on both surfaces of the negative electrode current collector 16b that is closer to the inside (two or more turns inside when viewed from the surplus portion 16D). Note that the negative electrode active material layer 16a may also be provided on the outer surface of the negative electrode 16 one circle inside from the outermost periphery (excess portion 16D). In addition, at the outermost periphery of the positive electrode 15, a positive electrode active material layer 15a is provided on the inner and outer surfaces of the positive electrode current collector 15b.
  • the surplus portion 16D when the battery 10 is heated from the outside, the surplus portion 16D has a heat diffusion effect and serves as a physical barrier to protect the battery case 22. Therefore, the influence of heat is alleviated, and the temperature rise at the outermost peripheral portion (S) of the electrode group 18 is suppressed. Furthermore, cracks in the battery case 22 due to a decrease in the strength of the battery case 22 are less likely to occur. In other words, even when a plurality of batteries are used in combination, the batteries are less likely to catch fire. Assuming that there is no surplus portion 16D, the outermost peripheral portion (S) is the portion that is most likely to become the starting point of thermal runaway when the battery is heated from the outside. Therefore, suppressing the temperature rise at the outermost circumferential portion (S) and protecting the battery case 22 are important measures to prevent fire outbreaks.
  • the negative electrode includes at least a negative electrode current collector, for example, a negative electrode current collector and a negative electrode active material layer (negative electrode mixture layer) formed on the surface of the negative electrode current collector and containing a negative electrode active material.
  • the negative electrode mixture layer can be formed by applying a negative electrode slurry in which the negative electrode mixture is dispersed in a dispersion medium onto the surface of the negative electrode current collector and drying it. The dried coating film may be rolled if necessary.
  • the negative electrode mixture layer may be formed on one surface or both surfaces of the negative electrode current collector.
  • the negative electrode mixture contains a negative electrode active material as an essential component, and can contain a binder, a conductive agent, a thickener, etc. as optional components.
  • the negative electrode active material includes a material that electrochemically inserts and releases lithium ions.
  • carbon materials, Si-containing materials, etc. can be used as the material that electrochemically absorbs and releases lithium ions.
  • Si-containing material include silicon oxide (SiOx: 0.5 ⁇ x ⁇ 1.5), a composite material containing a silicate phase and silicon particles dispersed within the silicate phase, and the like.
  • Examples of carbon materials include graphite, easily graphitizable carbon (soft carbon), and non-graphitizable carbon (hard carbon). Among these, graphite is preferable because it has excellent charging/discharging stability and low irreversible capacity.
  • Graphite refers to a material having a graphite-type crystal structure, and includes natural graphite, artificial graphite, graphitized mesophase carbon particles, and the like. One type of carbon material may be used alone, or two or more types may be used in combination.
  • a composite material containing a silicate phase and silicon particles dispersed within the silicate phase can easily achieve high capacity because the content of silicon particles can be arbitrarily selected.
  • the silicate phase is a complex oxide phase containing silicon, oxygen, alkali metals, and the like.
  • a composite material in which the silicate phase is a lithium silicate phase containing silicon, oxygen, and lithium will also be referred to as "LSX".
  • LSX absorbs lithium ions by alloying silicon with lithium. By increasing the content of silicon particles, high capacity can be expected.
  • the crystallite size of silicon particles dispersed within the lithium silicate phase is, for example, 5 nm or more. Silicon particles have a particulate phase of simple silicon (Si). When the crystallite size of the silicon particles is 5 nm or more, the surface area of the silicon particles can be kept small, so that deterioration of the silicon particles accompanied by generation of irreversible capacitance is less likely to occur.
  • the crystallite size of a silicon particle is calculated from the half-width of a diffraction peak attributed to the Si (111) plane of an X-ray diffraction (XRD) pattern of the silicon particle using the Scherrer equation.
  • LSX and a carbon material may be used in combination. Since the volume of LSX expands and contracts as it is charged and discharged, when its proportion in the negative electrode active material becomes large, poor contact between the negative electrode active material and the negative electrode current collector is likely to occur as the LSX is charged and discharged. On the other hand, by using LSX and a carbon material together, it is possible to achieve excellent cycle characteristics while imparting the high capacity of silicon particles to the negative electrode.
  • the proportion of LSX in the total of LSX and carbon material is preferably 3 to 30% by mass, for example. This makes it easier to achieve both higher capacity and improved cycle characteristics.
  • negative electrode current collector metal foil, mesh body, net body, punched sheet, etc. are used.
  • Examples of the material of the negative electrode current collector include stainless steel, nickel, nickel alloy, copper, and copper alloy.
  • a resin material is used as the binder for the negative electrode.
  • the binder include fluororesins, polyolefin resins, polyamide resins, polyimide resins, acrylic resins, vinyl resins, rubber-like materials (for example, styrene-butadiene copolymer (SBR)), and the like.
  • SBR styrene-butadiene copolymer
  • One type of binder may be used alone, or two or more types may be used in combination.
  • thickener examples include cellulose derivatives such as cellulose ether.
  • examples of cellulose derivatives include carboxymethylcellulose (CMC), modified products thereof, and methylcellulose.
  • CMC carboxymethylcellulose
  • One type of thickener may be used alone, or two or more types may be used in combination.
  • Examples of the conductive material include carbon nanotubes (CNT), carbon fibers other than CNT, and conductive particles (eg, carbon black, graphite).
  • CNT carbon nanotubes
  • carbon fibers other than CNT carbon fibers other than CNT
  • conductive particles eg, carbon black, graphite
  • the dispersion medium used in the negative electrode slurry is not particularly limited, and examples thereof include water, alcohol, N-methyl-2-pyrrolidone (NMP), and mixed solvents thereof.
  • the negative electrode current collector for example, metal foil can be used.
  • the negative electrode current collector may be porous.
  • Examples of the material of the negative electrode current collector include stainless steel, nickel, nickel alloy, copper, and copper alloy.
  • the thickness of the negative electrode current collector is not particularly limited, but is, for example, 1 to 50 ⁇ m, and may be 5 to 30 ⁇ m.
  • the positive electrode includes, for example, a positive electrode current collector and a positive electrode active material layer (positive electrode mixture layer) formed on the surface of the positive electrode current collector and containing a positive electrode active material.
  • the positive electrode mixture layer can be formed by applying a positive electrode slurry in which the positive electrode mixture is dispersed in a dispersion medium onto the surface of the positive electrode current collector and drying the slurry. The dried coating film may be rolled if necessary.
  • the positive electrode mixture layer may be formed on one surface or both surfaces of the positive electrode current collector.
  • the positive electrode mixture contains a positive electrode active material as an essential component, and may contain a binder, a thickener, etc. as optional components.
  • the positive electrode active material may be any material that can be used as a positive electrode active material for non-aqueous electrolyte secondary batteries (particularly lithium ion secondary batteries), but from the viewpoint of increasing capacity, lithium transition metals containing at least nickel as a transition metal are preferred.
  • the proportion of the composite oxide N in the positive electrode active material is, for example, 70% by mass or more, may be 90% by mass or more, or may be 95% by mass or more.
  • the composite oxide N may be, for example, a lithium transition metal composite oxide that has a layered rock salt type structure and includes Ni and at least one selected from the group consisting of Co, Mn, and Al.
  • it has a layered rock salt type structure and contains Ni and at least one member selected from the group consisting of Co, Mn, and Al, and the proportion of Ni in metal elements other than Li is 80 atomic % or more
  • the lithium transition metal composite oxide is also referred to as "composite oxide HN.”
  • the proportion of the composite oxide HN in the composite oxide N used as the positive electrode active material is, for example, 90% by mass or more, may be 95% by mass or more, or may be 100%. The higher the proportion of Ni, the more lithium ions can be extracted from the composite oxide HN during charging, and the capacity can be increased.
  • Co, Mn, and Al contribute to stabilizing the crystal structure of the composite oxide HN with a high Ni content.
  • the composite oxide HN is represented by the formula: Li ⁇ Ni (1-x1-x2-yz) Co x1 Mn x2 Al y M z O 2+ ⁇ , for example.
  • Element M is an element other than Li, Ni, Co, Mn, Al, and oxygen.
  • Mn contributes to stabilizing the crystal structure of the composite oxide HN, and since the composite oxide HN contains inexpensive Mn, it is advantageous for cost reduction.
  • Al contributes to stabilizing the crystal structure of the composite oxide HN.
  • ⁇ indicating the atomic ratio of lithium is, for example, 0.95 ⁇ 1.05. ⁇ increases and decreases with charging and discharging. In (2+ ⁇ ) indicating the atomic ratio of oxygen, ⁇ satisfies -0.05 ⁇ 0.05.
  • x1, which indicates the atomic ratio of Co is, for example, 0.1 or less (0 ⁇ x1 ⁇ 0.1)
  • x2, which indicates the atomic ratio of Mn is, for example, 0.1 or less (0 ⁇ x2 ⁇ 0.1).
  • y indicating the atomic ratio of Al is, for example, 0.1 or less (0 ⁇ y ⁇ 0.1)
  • z indicating the atomic ratio of the element M is, for example, 0 ⁇ z ⁇ 0.10. It is.
  • the element M may be at least one selected from the group consisting of Ti, Zr, Nb, Mo, W, Fe, Zn, B, Si, Mg, Ca, Sr, Sc, and Y. Among them, when at least one selected from the group consisting of Nb, Sr, and Ca is contained in the composite oxide HN, the surface structure of the composite oxide HN is stabilized, the resistance is reduced, and metal elution is further reduced. It is considered to be suppressed. Element M is more effective if it is unevenly distributed near the particle surface of the composite oxide HN.
  • binder for the positive electrode for example, a resin material is used.
  • the binder include fluororesin, polyolefin resin, polyamide resin, polyimide resin, acrylic resin, and vinyl resin.
  • One type of binder may be used alone, or two or more types may be used in combination.
  • Examples of the conductive material include carbon nanotubes (CNT), carbon fibers other than CNT, and conductive particles (eg, carbon black, graphite).
  • CNT carbon nanotubes
  • carbon fibers other than CNT carbon fibers other than CNT
  • conductive particles eg, carbon black, graphite
  • the dispersion medium used in the positive electrode slurry is not particularly limited, and examples include water, alcohol, N-methyl-2-pyrrolidone (NMP), and mixed solvents thereof.
  • the positive electrode current collector may be porous.
  • the porous current collector include a net, a punched sheet, and an expanded metal.
  • the material for the positive electrode current collector include stainless steel, aluminum, aluminum alloy, and titanium.
  • the thickness of the positive electrode current collector is not particularly limited, but is, for example, 1 to 50 ⁇ m, and may be 5 to 30 ⁇ m.
  • the nonaqueous electrolyte may be a liquid electrolyte (electrolytic solution), a gel electrolyte, or a solid electrolyte.
  • the gel electrolyte contains a lithium salt and a matrix polymer, or alternatively contains a lithium salt, a nonaqueous solvent, and a matrix polymer.
  • the matrix polymer for example, a polymer material that absorbs a non-aqueous solvent and gels is used. Examples of the polymer material include fluororesin, acrylic resin, polyether resin, polyethylene oxide, and the like.
  • the solid electrolyte may be an inorganic solid electrolyte.
  • inorganic solid electrolyte for example, materials known for use in all-solid lithium ion secondary batteries and the like (eg, oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.) are used.
  • the liquid electrolyte (electrolyte solution) includes a non-aqueous solvent and a solute dissolved in the non-aqueous solvent.
  • a solute is an electrolyte salt that ionically dissociates in a non-aqueous electrolyte.
  • the solute includes a lithium salt.
  • the non-aqueous electrolyte may contain various additives.
  • cyclic carbonate for example, cyclic carbonate, chain carbonate, cyclic carboxylic acid ester, chain carboxylic ester, etc. are used.
  • cyclic carbonate examples include propylene carbonate (PC), ethylene carbonate (EC), vinylene carbonate (VC), and the like.
  • chain carbonate esters examples include diethyl carbonate (DEC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC).
  • examples of the cyclic carboxylic acid ester include ⁇ -butyrolactone (GBL) and ⁇ -valerolactone (GVL).
  • chain carboxylic acid esters examples include methyl acetate, ethyl acetate, propyl acetate, methyl propionate (MP), and ethyl propionate (EP).
  • the non-aqueous solvents may be used alone or in combination of two or more.
  • lithium salts include lithium salts of chlorine-containing acids (LiClO 4 , LiAlCl 4 , LiB 10 Cl 10 , etc.), lithium salts of fluorine-containing acids (LiPF 6 , LiPF 2 O 2 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 etc.), lithium salts of fluorine-containing acid imides (LiN(FSO 2 ) 2 , LiN(CF 3 SO 2 ) 2 , LiN(CF 3 SO 2 )(C 4 F 9 SO 2 ), LiN (C 2 F 5 SO 2 ) 2 , etc.), lithium halide (LiCl, LiBr, LiI, etc.), etc. can be used.
  • One type of lithium salt may be used alone, or two or more types may be used in combination.
  • the concentration of the lithium salt in the non-aqueous electrolyte may be 1 mol/liter or more and 2 mol/liter or less, or 1 mol/liter or more and 1.5 mol/liter or less.
  • the lithium salt concentration is not limited to the above.
  • the separator has high ion permeability, appropriate mechanical strength, and insulation properties.
  • a microporous thin film, woven fabric, nonwoven fabric, etc. can be used.
  • a separator having a heat-resistant layer may also be used.
  • a separator having a heat-resistant layer may include a base material and a heat-resistant layer.
  • the heat-resistant layer is an insulating layer formed on at least one main surface selected from the two main surfaces of the base material.
  • the heat-resistant layer suppresses shrinkage of the base material when the temperature of the electrode group increases excessively. By including the heat-resistant layer in the separator, shrinkage of the base material is suppressed, so that internal short circuits are less likely to occur, and temperature rise at the outermost periphery (S) is more effectively suppressed.
  • the base material may be a separator used in lithium secondary batteries or lithium ion secondary batteries.
  • the base material may be, for example, a porous membrane containing a polyolefin resin. Polyolefin resins are desirable because they are excellent in durability and have a function of closing the pores when the temperature rises to a certain level (that is, a shutdown function).
  • the base material may have a single layer structure, a two layer structure, or a three or more layer structure.
  • the heat-resistant layer may include inorganic particles (or inorganic filler) and a polymer (or polymer or resin).
  • the polymer binds the inorganic particles to the substrate.
  • As the polymer it is desirable to use a heat-resistant resin that has higher heat resistance than the main component of the base material.
  • the heat-resistant layer may contain inorganic particles as a main component (for example, 80% by mass or more), or may contain a heat-resistant resin as a main component (for example, 40% by mass or more).
  • the heat-resistant layer may not contain inorganic particles but may contain a heat-resistant resin.
  • polyamide resin polyimide resin, polyamide-imide resin, etc.
  • polyamide-imide resin polyamide-imide resin, etc.
  • aromatic polyamide aromatic polyimide
  • aromatic polyamide-imide aromatic polyamide-imide.
  • These polymers are known to have particularly high heat resistance. From the viewpoint of heat resistance, aramids, ie, meta-aramids (meta-based wholly aromatic polyamides) and para-based aramids (para-based wholly aromatic polyamides) are preferred.
  • the inorganic particles are preferably at least one selected from the group consisting of aluminum oxide, boehmite, talc, titanium oxide, and magnesium oxide in terms of insulation and heat resistance.
  • the thickness of the heat-resistant layer may be 3% to 50% of the thickness of the separator.
  • the heat-resistant layers are formed on each of the two main surfaces of the base material, their total may be 3% to 50% of the thickness of the separator.
  • Examples 1 to 3 ⁇ (a) Preparation of positive electrode 100 parts by mass of positive electrode active material (LiNi 0.92 Co 0.04 Al 0.04 O 2 ), 1.0 parts by mass of acetylene black as a conductive material, and polyvinylidene fluoride (PVDF) as a binder.
  • a positive electrode slurry was prepared by mixing with N-methyl-2-pyrrolidone (NMP). The amount of PVDF was 0.9 parts by mass per 100 parts by mass of the positive electrode active material.
  • NMP N-methyl-2-pyrrolidone
  • the amount of PVDF was 0.9 parts by mass per 100 parts by mass of the positive electrode active material.
  • the coating film was dried and rolled with a roller to form a positive electrode active material layer.
  • the thickness of the two positive electrode active material layers attached to both surfaces of the positive electrode current collector was 70 ⁇ m. Thereafter, the positive electrode was cut into strips.
  • SBR styrene-butadiene rubber
  • the amount of SBR was 1.0 parts by mass per 100 parts by mass of the negative electrode active material.
  • the negative electrode current collector and separator were wound to form a cylindrical part.
  • the diameter of the hollow space inside the cylindrical part was 4 mm.
  • a predetermined surplus portion was formed on the first electrode (negative electrode).
  • the length L1 of the surplus portion along the circumferential direction of the electrode group is 100% (one round of the outermost circumference) of the circumferential length L of the outermost negative electrode in Example 1, and approximately 400% in Example 2. (for 4 turns from the outermost circumference), and about 800% of Example 3 (for 8 turns from the outermost circumference).
  • the excess portion was wrapped around the outer surface of the inner negative electrode without using a separator.
  • a cylindrical lithium ion secondary battery as shown in FIG. 1 was produced according to the following procedure.
  • An upper insulating plate and a lower insulating plate were arranged on the upper and lower end surfaces of the electrode group, and the electrode group was housed in a battery case (side wall thickness: 220 ⁇ m) made of steel (SPCE) and having an opening and a bottomed cylinder.
  • the negative electrode lead was welded to the inside of the bottom of the battery case.
  • an annular groove was formed above the upper insulating plate and near the open end of the battery case.
  • a nonaqueous electrolyte is injected into the battery case under reduced pressure, and then the sealing plate is placed in the annular groove so as to close the opening of the battery case. I placed it.
  • a gasket was previously placed on the peripheral edge of the sealing plate, and the open end of the battery case was caulked to the sealing plate via this gasket, thereby completing a cylindrical 21700 size lithium ion secondary battery.
  • the completed lithium ion secondary battery is charged to 4.2V with a constant current equivalent to 0.3C, and then pre-charged and discharged to 2.5V with a constant current equivalent to 0.5C, which corresponds to the initial state.
  • a lithium ion secondary battery was obtained.
  • Example 4 A cylindrical part was formed by winding the positive electrode, the negative electrode, and the separator in one rotation from the end of the electrode group at the beginning of winding. A lithium ion secondary battery was obtained in the same manner as in Example 1 except for this point.
  • the evaluation results are shown in Table 1.
  • the batteries of Examples 1 to 4 are batteries A1 to A4, and the batteries of Comparative Examples 1 to 3 are batteries B1 to B3.
  • the discharge capacity of the batteries of each example is a relative ratio when the discharge capacity of battery A1 is taken as 100%.
  • the ratio (R) of the number of batteries with cracks in the side wall of the battery case was significantly reduced compared to battery B1.
  • the ratio (R) of the number of batteries with cracks in the side wall of the battery case was significantly decreased.
  • the safety valve operates normally and the occurrence of cracks in the side wall of the battery case is suppressed.
  • the ratio (R) of battery A1 was low. This is understood to be because the hollow space of the battery A1 becomes a passage for the gas generated inside the battery, and the function of discharging the gas to the outside through the safety valve is improved.
  • the nonaqueous electrolyte secondary battery according to the present disclosure is useful as a main power source for mobile communication devices, portable electronic devices, electric vehicles, and the like.
  • Nonaqueous electrolyte secondary battery 11 Sealing body 12
  • Valve body 13 Metal plate 14
  • Insulating member 15 Positive electrode 15L Positive electrode lead 15a Positive electrode active material layer 15b
  • Positive electrode current collector 16 Negative electrode 16L Negative electrode lead 16a Negative electrode active material layer 16b
  • Negative electrode current collector 16D Surplus portion 17
  • Separator 18 Electrode group 21 Gasket 22 Battery case 22a Groove

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PCT/JP2023/011177 2022-03-24 2023-03-22 非水電解質二次電池 Ceased WO2023182341A1 (ja)

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JP2024509153A JPWO2023182341A1 (https=) 2022-03-24 2023-03-22
EP23774936.1A EP4503239A4 (en) 2022-03-24 2023-03-22 SECONDARY BATTERY WITH NON-AQUEOUS ELECTROLYTE
CN202380029319.4A CN118922980A (zh) 2022-03-24 2023-03-22 非水电解质二次电池

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JPH06150973A (ja) * 1992-11-04 1994-05-31 Nippon Telegr & Teleph Corp <Ntt> 非水電解液二次電池
JP2002231215A (ja) * 2001-01-31 2002-08-16 Sanyo Electric Co Ltd 溶接封口電池
JP2003297432A (ja) 2002-04-04 2003-10-17 Sony Corp 非水電解質二次電池
JP2004356047A (ja) * 2003-05-30 2004-12-16 Canon Inc リチウム二次電池
WO2013014833A1 (ja) * 2011-07-25 2013-01-31 パナソニック株式会社 リチウムイオン二次電池
WO2018116876A1 (ja) * 2016-12-22 2018-06-28 三洋電機株式会社 円筒形の非水電解質二次電池
WO2019098023A1 (ja) * 2017-11-16 2019-05-23 パナソニックＩｐマネジメント株式会社 円筒形二次電池

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Publication number Priority date Publication date Assignee Title
WO2020262437A1 (ja) * 2019-06-28 2020-12-30 三洋電機株式会社 円筒形非水電解質二次電池

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Publication number Priority date Publication date Assignee Title
JPH06150973A (ja) * 1992-11-04 1994-05-31 Nippon Telegr & Teleph Corp <Ntt> 非水電解液二次電池
JP2002231215A (ja) * 2001-01-31 2002-08-16 Sanyo Electric Co Ltd 溶接封口電池
JP2003297432A (ja) 2002-04-04 2003-10-17 Sony Corp 非水電解質二次電池
JP2004356047A (ja) * 2003-05-30 2004-12-16 Canon Inc リチウム二次電池
WO2013014833A1 (ja) * 2011-07-25 2013-01-31 パナソニック株式会社 リチウムイオン二次電池
WO2018116876A1 (ja) * 2016-12-22 2018-06-28 三洋電機株式会社 円筒形の非水電解質二次電池
WO2019098023A1 (ja) * 2017-11-16 2019-05-23 パナソニックＩｐマネジメント株式会社 円筒形二次電池

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Title
See also references of EP4503239A4

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CN118922980A (zh) 2024-11-08

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