WO2024159521A1 - 一种二次电池和电子装置 - Google Patents

一种二次电池和电子装置 Download PDF

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Publication number
WO2024159521A1
WO2024159521A1 PCT/CN2023/074396 CN2023074396W WO2024159521A1 WO 2024159521 A1 WO2024159521 A1 WO 2024159521A1 CN 2023074396 W CN2023074396 W CN 2023074396W WO 2024159521 A1 WO2024159521 A1 WO 2024159521A1
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WIPO (PCT)
Prior art keywords
negative electrode
secondary battery
groove
present application
electrode sheet
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PCT/CN2023/074396
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English (en)
French (fr)
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WO2024159521A9 (zh
Inventor
孔森
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Ningde Amperex Technology Ltd
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Ningde Amperex Technology Ltd
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Priority to CN202380009414.8A priority Critical patent/CN116830348A/zh
Priority to JP2025544994A priority patent/JP2026505815A/ja
Priority to PCT/CN2023/074396 priority patent/WO2024159521A1/zh
Priority to EP23919097.8A priority patent/EP4661091A4/en
Publication of WO2024159521A1 publication Critical patent/WO2024159521A1/zh
Publication of WO2024159521A9 publication Critical patent/WO2024159521A9/zh
Anticipated expiration legal-status Critical
Priority to US19/289,417 priority patent/US20250364529A1/en
Ceased legal-status Critical Current

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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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • H01M50/461—Separators, membranes or diaphragms characterised by their combination with electrodes with adhesive layers between electrodes and 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of electrochemical technology, and in particular to a secondary battery and an electronic device.
  • Secondary batteries such as lithium-ion batteries
  • lithium-ion batteries During repeated charge and discharge cycles, lithium-ion batteries will accumulate stress inside and cause deformation, which can lead to problems such as excessive thickness and accelerated cycle decay, affecting the cycle stability of lithium-ion batteries.
  • problems such as excessive thickness and accelerated cycle decay, affecting the cycle stability of lithium-ion batteries.
  • heat As heat accumulates inside lithium-ion batteries during the cycle, if the heat cannot be dissipated in time, the risk of thermal runaway will increase, affecting the safety of lithium-ion batteries.
  • the purpose of the present application is to provide a secondary battery and an electronic device with good cycle stability and safety.
  • lithium-ion batteries are used as an example of secondary batteries to explain the present application, but the secondary batteries of the present application are not limited to lithium-ion batteries.
  • the specific technical solution is as follows:
  • the present application provides a secondary battery, which includes an electrode assembly, wherein the electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator, wherein the separator is arranged between the positive electrode sheet and the negative electrode sheet, and the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, wherein the surface of the negative electrode active material layer opposite to the positive electrode sheet has a groove, and the depth of the groove is H ⁇ m; the separator includes a substrate layer and a bonding layer arranged on the surface of the separator opposite to the negative electrode sheet, and the thickness of the bonding layer is T ⁇ m, satisfying: H ⁇ T+1.
  • the present application can improve the conduction effect of the groove on the electrolyte and the high-temperature gas generated under high temperature conditions by regulating the depth of the groove and the thickness of the bonding layer to meet the scope of the present application, thereby increasing the heat dissipation capacity inside the secondary battery and improving the high temperature performance of the secondary battery.
  • the cross-sectional area of the groove is A ⁇ m 2
  • the width of the groove is W ⁇ m
  • the following conditions are satisfied: 0.35 ⁇ (W ⁇ H) ⁇ A ⁇ 0.95(W ⁇ H), 5 ⁇ H ⁇ 100.
  • 1 ⁇ W/H ⁇ 40 Preferably, 2 ⁇ W/H ⁇ 20, which can further improve the heat dissipation capacity inside the lithium-ion battery and improve the cycle stability and safety of the lithium-ion battery at high temperatures.
  • the width of the groove is W ⁇ m
  • the spacing of the grooves is S ⁇ m
  • the porosity of the negative electrode sheet is P%, satisfying:
  • Adjusting the negative electrode plate porosity, groove width and groove spacing to satisfy the above relationship can effectively improve the thermal balance of the plate under high temperature conditions, enhance the thermal diffusion efficiency under extreme environments, reduce the risk of thermal runaway of lithium-ion batteries, and improve the safety performance of lithium-ion batteries. It can also release the internal stress generated during the high-temperature cycle of lithium-ion batteries through the space provided by the grooves, thereby improving the problem of cyclic deformation of lithium-ion batteries and improving the cyclic stability of lithium-ion batteries.
  • the spacing of the grooves is S ⁇ m
  • the bonding force between the separator and the negative electrode plate is F N/m, satisfying: S ⁇ 1000F, 500 ⁇ S ⁇ 10000, preferably, S ⁇ 650F. It can improve the heat dissipation capacity inside the lithium-ion battery, reduce the risk of thermal runaway of the lithium-ion battery, and improve the safety performance of the lithium-ion battery.
  • 0.1 ⁇ T ⁇ 10 0.1 ⁇ T ⁇ 10.
  • the bonding layer includes a polymer, and based on the mass of the bonding layer, the content of the polymer is 25% to 100%, preferably, the content of the polymer is 30% to 100%, and more preferably, the content of the polymer is 50% to 100%.
  • the bonding force between the separator and the negative electrode is F N/m, satisfying: 1 ⁇ F ⁇ 50. Preferably, 5 ⁇ F ⁇ 30. Further preferably, 7 ⁇ F ⁇ 30.
  • the polymer includes polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer At least one of a styrene-butadiene copolymer, polyacrylonitrile, butadiene-acrylonitrile polymer, polyacrylic acid, polyacrylate or acrylate-styrene copolymer.
  • the negative electrode sheet further includes a negative electrode tab, a first groove portion is provided along the length direction of the negative electrode tab, and the negative electrode active material layer is provided between the first groove portion and the negative electrode tab along the length direction of the negative electrode tab; wherein the distance between the first groove portion and the negative electrode tab is d mm, 0.2 ⁇ d ⁇ 5.
  • the heat dispersion effect under high temperature conditions can be optimized, and on the other hand, due to the retention of the negative electrode active material layer between the groove and the tab region along the length direction of the negative electrode tab, the ion conduction in the tab region can be further improved, the regional electrochemical interface can be improved, and thus the cycle performance of the secondary battery can be improved.
  • the separation design of the groove and the tab region can avoid secondary processing of the local area of the current collector, thereby improving the yield rate of the negative electrode sheet.
  • the second aspect of the present application provides an electronic device, which includes the secondary battery described in the above embodiment.
  • the electronic device has good high-temperature cycle stability and safety.
  • the present application provides a secondary battery and an electronic device, wherein the surface of the negative electrode active material layer opposite to the positive electrode plate has a groove, and the depth of the groove is H ⁇ m; the separator includes a substrate layer and a bonding layer disposed on the surface of the separator opposite to the negative electrode plate, and the thickness of the bonding layer is T ⁇ m, satisfying: H ⁇ T+1.
  • the present application satisfies the scope of the present application by regulating the depth of the groove and the thickness of the bonding layer, thereby increasing the heat dissipation capacity inside the secondary battery and improving the high temperature performance of the secondary battery.
  • FIG1 is a schematic diagram of the structure of an electrode assembly in some embodiments of the present application.
  • FIG2 is a schematic diagram of a partial cross-sectional structure of an electrode assembly along its thickness direction in some embodiments of the present application
  • FIG3 is a schematic diagram of a partial cross-sectional structure of a negative electrode sheet along its thickness direction in some embodiments of the present application;
  • FIG4 is a partial top view of a negative electrode sheet along its thickness direction in some embodiments of the present application.
  • FIG5 is a schematic diagram of a cross-sectional structure of a diaphragm along its thickness direction in some embodiments of the present application.
  • FIG6 is a schematic diagram of a cross-sectional structure of a diaphragm along its thickness direction in other embodiments of the present application.
  • FIG7 is a schematic diagram of the structure of a negative electrode sheet in some embodiments of the present application.
  • FIG8 is a schematic diagram of groove profile determination and groove parameter measurement in some implementation schemes of the present application.
  • Figure numerals 10 - electrode assembly, 20 - positive electrode plate, 21 - positive electrode collector, 22 - positive electrode active material layer, 30 - negative electrode plate, 31 - negative electrode collector, 32 - negative electrode active material layer, 33 - negative electrode tab, 34 - empty foil area, 40 - separator, 41 - substrate layer, 42 - inorganic coating, 43 - bonding layer, 321 - groove, 322 - first groove portion.
  • the lithium-ion battery is used as an example of a secondary battery to explain the present application, but the secondary battery of the present application is not limited to the lithium-ion battery.
  • the specific technical solution is as follows:
  • a secondary battery is provided, as shown in FIG1 , which includes an electrode assembly 10, wherein the X direction is the length direction of the electrode assembly 10 itself, the Y direction is the width direction of the electrode assembly 10 itself, and the Z direction is the thickness direction of the electrode assembly 10 itself.
  • the electrode assembly 10 includes a positive electrode sheet 20, a negative electrode sheet 30 and a separator 40, wherein the separator 40 is disposed between the positive electrode sheet 20 and the negative electrode sheet 30, the positive electrode sheet 20 includes a positive electrode current collector 21 and a positive electrode active material layer 22, and the negative electrode sheet 30 includes a negative electrode current collector 31 and a negative electrode active material layer 32, wherein the surface of the negative electrode active material layer 32 opposite to the positive electrode sheet 20 has a groove 321. As shown in FIG3 , the depth of the groove is H ⁇ m.
  • the separator 40 includes a substrate layer 41 and a bonding layer 43, and the thickness of the bonding layer is T ⁇ m, satisfying: H ⁇ T+1, preferably, H ⁇ T+5.
  • the bonding layer 43 may be a surface layer of the separator 40 opposite to the negative electrode plate 30 .
  • this application can improve the dispersion effect of the groove on the high-temperature heat generated under high temperature conditions by regulating the depth of the groove and the thickness of the adhesive layer to meet the scope of this application, thereby improving the heat dissipation capacity of the lithium-ion battery inside, and improving the high-temperature performance of the lithium-ion battery, such as improving the cycle stability and safety of the lithium-ion battery under high temperature.
  • the negative electrode active material layer 32 can be set on one side or on both sides.
  • the cross-sectional area of the groove is A ⁇ m 2
  • the width of the groove is W ⁇ m
  • the following conditions are satisfied: 0.35 ⁇ (W ⁇ H) ⁇ A ⁇ 0.95(W ⁇ H), 5 ⁇ H ⁇ 100.
  • the interface morphology at the groove can be adjusted, thereby further improving the interface heat dispersion effect of the pole piece under high-temperature hot box conditions, improving the heat dissipation capacity inside the lithium-ion battery, and improving the electrochemical bonding between the isolation film bonding layer and the pole piece at the groove, thereby improving the cycle stability and safety of the lithium-ion battery at high temperature.
  • 1 ⁇ W/H ⁇ 40 Preferably, 2 ⁇ W/H ⁇ 20.
  • W and H By further regulating W and H to satisfy the above relationship, the heat dissipation capacity inside the lithium-ion battery can be further improved, and the cycle stability and safety of the lithium-ion battery at high temperature can be improved.
  • the width of the groove is W ⁇ m
  • the spacing of the groove is S ⁇ m
  • the porosity of the negative electrode sheet is P%, satisfying:
  • the failure of the high-temperature hot box is mainly due to the contact between the surface of the active material layer of the negative electrode plate and the electrolyte, and side reactions occur under high temperature conditions. The heat generated by the side reactions accumulates inside the battery, and the risk of thermal runaway increases.
  • the porosity of the negative electrode plate is larger, the area of contact between the negative electrode active material layer and the electrolyte is larger, the more heat is generated, and the greater the risk of thermal runaway.
  • the present application can improve the dispersion effect of the groove on the heat generated under high-temperature hot box conditions by regulating the width of the groove, the spacing of the groove, and the porosity of the negative electrode plate to meet the above relationship, improve the heat diffusion efficiency under extreme environments, reduce the risk of thermal runaway of lithium-ion batteries, improve the safety performance of lithium-ion batteries, and can also effectively disperse the gas produced during high-temperature cycles through the grooves, improve the interface electrochemical properties between the diaphragm and the pole piece, and improve the high-temperature cycle stability of lithium-ion batteries.
  • the negative electrode sheet of the lithium ion battery satisfies 5 ⁇ P ⁇ 50.
  • 10 ⁇ P ⁇ 40 Preferably, 10 ⁇ P ⁇ 30.
  • the spacing of the grooves is S ⁇ m
  • the bonding force between the diaphragm and the negative electrode plate is F N/m, satisfying: S ⁇ 1000F, 500 ⁇ S ⁇ 10000, preferably, S ⁇ 650F.
  • the inventors have found that different types of diaphragms have different interfacial bonding properties. A diaphragm with high bonding properties has a good effect on improving the deformation of lithium-ion batteries, but the heat dissipation effect will be reduced.
  • the present application adjusts the above relationship between S and F to meet the above relationship, targeting Diaphragms with different bonding properties can also enhance the conduction effect of the grooves on the high-temperature gas generated under high-temperature hot box conditions, thereby improving the heat dissipation capacity inside the lithium-ion battery, reducing the risk of thermal runaway of the lithium-ion battery, and improving the safety performance of the lithium-ion battery.
  • 0.1 ⁇ T ⁇ 10 0.1 ⁇ T ⁇ 10.
  • the bonding layer includes a polymer; wherein, based on the mass of the bonding layer, the content of the polymer is 25% to 100%, preferably, the content of the polymer is 30% to 100%.
  • the bonding layer 43 is located on the surface of the substrate layer 41, and the bonding layer 43 includes a polymer and an inorganic material.
  • the synergistic effect of the above structural design and material selection is conducive to improving the interfacial bonding force of the diaphragm, thereby improving the deformation problem of the lithium-ion battery and improving the cycle stability and safety of the lithium-ion battery at high temperatures.
  • the separator further includes an inorganic coating 42, the inorganic coating 42 is located between the substrate layer 41 and the bonding layer 43, the inorganic coating 42 includes an inorganic material, and the bonding layer 43 includes a polymer.
  • the synergistic effect of the above structural design and material selection is conducive to improving the interfacial bonding force of the separator, thereby improving the deformation problem of the lithium-ion battery and improving the cycle stability and safety of the lithium-ion battery at high temperatures.
  • 1 ⁇ F ⁇ 50 Preferably, 5 ⁇ F ⁇ 30. Further preferably, 7 ⁇ F ⁇ 30.
  • the polymer includes at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, styrene-butadiene copolymer, polyacrylonitrile, butadiene-acrylonitrile polymer, polyacrylic acid, polyacrylate or acrylate-styrene copolymer.
  • the separator includes the above polymer, it is beneficial to improve the interfacial bonding performance of the separator.
  • the negative electrode tab 33 is usually welded to the empty foil area 34 of the negative electrode sheet 30 (the negative electrode is not coated in the negative electrode sheet).
  • the negative electrode sheet 30 also includes a negative electrode tab 33, and the groove 321 is arranged along the length direction (i.e., the Y direction) of the negative electrode tab 33.
  • a first groove portion 322 is arranged along the length direction of the negative electrode tab 33, and a negative electrode active material layer is arranged between the first groove portion 322 and the negative electrode tab 33 along the length direction of the negative electrode tab 33; wherein the distance between the first groove portion 322 and the negative electrode tab 33 is d mm, 0.2 ⁇ d ⁇ 5.
  • the present application can, on the one hand, optimize the heat dispersion effect under high temperature conditions; on the other hand, due to the retention of the negative electrode active material layer between the groove and the lug area along the length direction of the negative electrode lug, it can further improve the ion conduction in the lug area and improve the regional electrochemical interface, thereby enhancing the cycle performance of the secondary battery.
  • the separation design of the groove and the lug area can avoid secondary processing of the local area of the current collector and improve the yield rate of the negative electrode sheet.
  • the electrode assembly of the present application may be a winding structure, and its electrode sheet generally has a long side and a short side after being unfolded.
  • the electrode assembly is a winding structure, and the width direction is the extension direction of the short side of the electrode sheet after being unfolded, and the length direction is the extension direction of the long side of the electrode sheet after being unfolded.
  • the electrode sheet of the present application includes a positive electrode sheet 20 and a negative electrode sheet 30.
  • the secondary battery of the present application may include any device that undergoes an electrochemical reaction, as long as it can achieve the purpose of the present application.
  • the secondary battery may include but is not limited to: a lithium-ion secondary battery (lithium-ion battery), a sodium-ion secondary battery, a lithium polymer secondary battery or a lithium-ion polymer secondary battery, etc.
  • the battery structure of the present application includes but is not limited to a soft-pack battery, a square hard-shell battery or a cylindrical hard-shell battery, etc.
  • the present application has no special restrictions on the negative electrode current collector, as long as the purpose of the present application can be achieved.
  • the negative electrode current collector may include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam or a composite current collector, etc.
  • the present application has no special restrictions on the thickness of the negative electrode current collector, as long as the purpose of the present application can be achieved.
  • the thickness of the negative electrode current collector is 4 ⁇ m to 10 ⁇ m.
  • the negative electrode active material layer can be arranged on one surface in the thickness direction of the negative electrode current collector, or on two surfaces in the thickness direction of the negative electrode current collector. It should be noted that the "surface" here can be the entire area of the negative electrode current collector or a partial area of the negative electrode current collector. This application has no special restrictions. There is no limitation, as long as the purpose of this application can be achieved.
  • the present application does not particularly limit the type of negative electrode active material, as long as the purpose of the present application can be achieved.
  • the negative electrode active material may include graphite, a mixture of graphite and silicon materials such as silicon, silicon oxide or silicon carbide, and the above graphite may be selected from artificial graphite or natural graphite.
  • the negative electrode active material layer also includes at least one of a conductive agent, a thickener, and a binder.
  • the present application does not particularly limit the types of conductive agents, thickeners, and binders in the negative electrode active material layer, as long as the purpose of the present application can be achieved.
  • the negative electrode binder may include, but is not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1,1-difluoride, polyethylene, polypropylene, polyacrylic acid, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, or at least one of nylon.
  • the present application has no particular restrictions on the mass ratio of the negative electrode active material, the conductive agent, the thickener and the binder in the negative electrode active material layer, as long as the purpose of the present application can be achieved.
  • the mass ratio of the negative electrode active material, the conductive agent, the thickener and the binder in the negative electrode active material layer is (96-98): (0-1.5): (0.5-1.5): (1.0-1.9).
  • the present application does not particularly limit the material of the diaphragm substrate layer, and those skilled in the art can select it according to actual needs, as long as the purpose of the present application can be achieved.
  • the material of the diaphragm substrate layer may include but is not limited to at least one of polyethylene, polypropylene, polyethylene terephthalate or polyimide, etc.
  • a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric or a polypropylene-polyethylene-polypropylene porous composite film can be used.
  • the secondary battery of the present application also includes an electrolyte.
  • the present application has no special restrictions on the electrolyte. Those skilled in the art can choose according to actual needs, as long as the purpose of the present application can be achieved.
  • ethylene carbonate also known as ethylene carbonate, abbreviated as EC
  • PC propylene carbonate
  • DEC diethyl carbonate
  • EP ethyl propionate
  • PP propyl propionate
  • EMC ethyl methyl carbonate
  • DMC dimethyl carbonate
  • VMC vinylene carbonate
  • FEC fluoroethylene carbonate
  • the present application has no special restrictions on the above-mentioned "mass ratio", as long as the purpose of the present application can be achieved.
  • the present application has no restrictions on the type of lithium salt, as long as the purpose of the present application can be achieved.
  • the lithium salt may include LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 CF 3 ) 2 , LiC(SO 2 CF 3 ) 3 , LiSiF 6 , At least one of lithium bis(oxalatoborate) (LiBOB) or lithium difluoroborate.
  • the present application has no particular limitation on the concentration of the lithium salt in the electrolyte, as long as the purpose of the present application can be achieved.
  • the concentration of the lithium salt is 1.0 mol/L to 2.0 mol/L.
  • the positive electrode sheet of the present application may include a positive electrode active material layer and a positive electrode current collector.
  • the present application has no particular restrictions on the type of positive electrode active material, as long as the purpose of the present application can be achieved.
  • the positive electrode active material may include at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide, lithium manganese oxide or lithium iron manganese phosphate.
  • the positive electrode active material may also include non-metallic elements, such as non-metallic elements including at least one of fluorine, phosphorus, boron, chlorine, silicon or sulfur, which can further improve the stability of the positive electrode active material.
  • the positive electrode active material layer of the present application may also include a conductive agent and a binder.
  • the present application has no particular restrictions on the mass ratio of the positive electrode active material, conductive agent and binder in the positive electrode active material layer, and those skilled in the art can choose according to actual needs, as long as the purpose of the present application can be achieved.
  • the mass ratio of the positive electrode active material, conductive agent and binder in the positive electrode active material layer is (96-98): (1-3): (2-3).
  • the present application has no special restrictions on the positive electrode current collector, as long as the purpose of the present application can be achieved.
  • the positive electrode current collector may include aluminum foil, aluminum alloy foil or a composite current collector, etc.
  • the present application has no special restrictions on the thickness of the positive electrode current collector, as long as the purpose of the present application can be achieved.
  • the thickness of the positive electrode current collector is 5 ⁇ m to 20 ⁇ m.
  • the positive electrode active material layer can be arranged on one surface in the thickness direction of the positive electrode current collector, or on two surfaces in the thickness direction of the positive electrode current collector. It should be noted that the "surface" here can be the entire area of the positive electrode current collector or a partial area of the positive electrode current collector.
  • the present application has no special restrictions, as long as the purpose of the present application can be achieved.
  • the preparation method of the negative electrode sheet includes but is not limited to the following steps: dispersing the negative electrode active material, the conductive agent, the thickener and the binder in deionized water to form a uniform negative electrode slurry, coating the negative electrode slurry on the negative electrode collector, drying and cold pressing, and then preparing grooves on the surface of the negative electrode sheet, and then cutting and slitting to obtain a negative electrode sheet with a structure as shown in Figure 3.
  • the preparation method of the positive electrode sheet includes but is not limited to the following steps: dispersing the positive electrode active material, the conductive agent and the binder in The positive electrode slurry is coated on the positive electrode collector, and the positive electrode sheet is obtained by drying, cold pressing, cutting and slitting.
  • the present application has no particular restrictions on the shape of the groove, as long as the purpose of the present application can be achieved.
  • the shape of the groove when viewed from the length direction of the negative electrode sheet, may include at least one of a square, a rectangle, a trapezoid, a triangle, or a semicircle; when viewed from the thickness direction of the negative electrode sheet, the shape of the groove may include at least one of a straight line, an oblique line, a broken line, or a curved line.
  • the present application has no particular restrictions on the method for preparing the grooves, as long as the purpose of the present application can be achieved.
  • it may include but is not limited to laser etching, mechanical processing or pore-forming agent processing.
  • laser etching the width and depth of the grooves usually increase with the increase of the laser power, and the spacing of the grooves can usually be adjusted by the laser processing rate. Therefore, technicians can adjust the width, depth, spacing and other parameters of the grooves by adjusting parameters such as the laser power, processing rate and the tape running rate of the pole piece.
  • the porosity of the negative electrode sheet usually decreases as the compaction density of the negative electrode sheet increases. Based on this, the porosity of the negative electrode sheet can be adjusted by adjusting the cold pressing pressure of the negative electrode sheet and adjusting the compaction density of the negative electrode sheet.
  • the preparation method of the secondary battery includes but is not limited to the following steps: stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and winding, folding and other operations as needed to obtain an electrode assembly with a wound structure, placing the electrode assembly in a packaging bag, injecting the electrolyte into the packaging bag and sealing it to obtain a secondary battery.
  • the second aspect of the present application provides an electronic device, which includes the secondary battery described in the above embodiment.
  • the electronic device has good cycle stability and safety.
  • the electronic device can include but is not limited to a laptop computer, a pen-input computer, a mobile computer, an electronic book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD television, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, Bicycles, lighting equipment, toys, game consoles, clocks, electric tools, flashlights, cameras, large household batteries or lithium-ion capacitors, etc.
  • a portion of the diaphragm that is not arranged opposite to the positive electrode active material layer or the negative electrode active material layer in the electrode assembly is selected, and the diaphragm cross section is prepared by ion beam profiling (CP). Then, the thickness of the bonding layer is measured by a scanning electron microscope (ZEISS Sigma/X-max).
  • Groove depth H and groove width W As shown in Figure 8, the depth difference between the deepest part of the groove and the reference surface is the groove depth. The distance between the intersections of the two sides of the groove and the reference surface is the groove width. Along the same groove, measure once every 10 ⁇ m, for a total of 20 times, calculate the average of the 20 depths and widths, and record the groove depth H and width W.
  • Groove spacing S For adjacent grooves (when viewed along the length of the pole piece, two adjacent grooves are considered adjacent if the overlapped portion of the grooves is greater than 50% of their respective lengths), the distance between the midpoints of the width of the two grooves in the vertical direction of the grooves is the groove spacing S. Along the selected grooves, measurements were taken every 10 ⁇ m for a total of 20 times, and the average value was calculated and recorded as the groove spacing S.
  • Groove area A Use a laser confocal microscope model VK-1050 to photograph the groove area and obtain the optical and depth information of the pole piece within the field of view of the microscope. At a magnification of 20 times, use the laser confocal mode to scan the pole piece surface. After scanning, obtain the depth data relative to the baseline at each pixel width. Within the above groove width range, the depth ( hi ) at each pixel width ( w0 ) is integrated to obtain the cross-sectional area A of the groove:
  • the porosity of the negative electrode sheet was tested by gas replacement method: 50 negative electrode sheets with a radius of d were punched out by the same mold, the thickness h of each negative electrode sheet was measured, and the 50 negative electrode sheets were placed in the sample cup of the testing equipment (AccuPyc ⁇ 1340), and the negative electrode sheets were filled with helium in the closed sample chamber, thereby measuring the true volume V of the negative electrode sheet, and then the porosity of the negative electrode sheet was calculated by the following formula: (1-V/ ⁇ d 2 ⁇ 50 ⁇ h) ⁇ 100%.
  • the lithium-ion battery was charged at a constant current of 0.7C to a voltage of 4.5V, then charged at a constant voltage of 4.5V to a current of 0.05C, and then discharged at a constant current of 1C to a voltage of 3.0V. This was considered a charge and discharge cycle. After 400 repeated charge and discharge cycles, the high-temperature capacity retention rate and high-temperature thickness expansion rate of the lithium-ion battery were tested.
  • Capacity retention rate of lithium-ion battery after 400 cycles discharge capacity after 400th cycle / discharge capacity after first cycle ⁇ 100%;
  • Thickness expansion rate of the lithium-ion battery after 400 cycles thickness of the lithium-ion battery after the 400th cycle / thickness of the lithium-ion battery at the first cycle ⁇ 100%.
  • Lithium-ion battery hot box pass rate test
  • the slurry was evenly coated on one surface of a negative electrode current collector copper foil with a thickness of 6 ⁇ m, and dried at 85°C to obtain a negative electrode sheet with a negative electrode active material layer thickness of 50 ⁇ m; then, the above steps were repeated on the other surface of the negative electrode sheet to obtain a negative electrode sheet with a double-sided coating of negative electrode active materials; then, the negative electrode sheet obtained above was cold pressed, and a groove was etched on the surface of the negative electrode active material layer by laser processing technology, and then after striping and cutting, the pole ear welding area was obtained by cleaning, and the pole ear was welded to obtain a negative electrode sheet.
  • the parameters such as the groove depth H, groove width W, groove spacing S, groove cross-sectional area, and porosity of the negative electrode sheet are shown in Table 1.
  • Lithium cobalt oxide, polyvinylidene fluoride, and conductive agent Super P were mixed in a mass ratio of 96:2:2, and N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75wt%, and stirred evenly.
  • NMP N-methylpyrrolidone
  • the slurry was evenly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 6 ⁇ m, and dried at 95°C to obtain a positive electrode sheet with a positive electrode active material layer thickness of 60 ⁇ m; then, the above steps were repeated on the other surface of the positive electrode sheet to obtain a positive electrode sheet with a double-sided coating of positive electrode active material; then, the above-obtained positive electrode sheet was cold pressed, striped, cut, and dried at 85°C for 4 hours under vacuum conditions, and then the tabs were welded to obtain a positive electrode sheet.
  • Ethylene carbonate, diethyl carbonate, methyl ethyl carbonate and vinylene carbonate are mixed in a mass ratio of 8:85:5:2 to obtain a non-aqueous organic solvent.
  • lithium salt LiPF6 is mixed with the non-aqueous organic solvent in a mass ratio of 8:92 to obtain an electrolyte.
  • a polypropylene film with a thickness of 5 ⁇ m was used.
  • the mass ratio of aluminum oxide ceramic particles, butadiene-styrene polymer and deionized water is 35:10:55.
  • a total of 30 kg of butadiene-styrene polymer and deionized water are added to a 60L double planetary mixer and dispersed at 45°C for 3 hours; then 16.1 kg of aluminum oxide ceramic powder is added to the mixer and dispersed at high speed at 45°C for 2 hours; then a nano grinder is used for ball milling for 1.5 hours, and the grinding medium used is spherical zirconium oxide beads with a diameter of 6 ⁇ m, to obtain an inorganic coating glue.
  • the substrate was coated on the surface by transfer coating, wherein the coating speed was 6 m/min, the coating amount was controlled to be 0.18 mg/cm 2 , and the coating thickness was 1.5 ⁇ m; a three-stage drying method was adopted, each section of the oven was 3 m long, and the oven setting temperature was 50°C, 60°C, and 60°C, to form a substrate layer including a single-sided inorganic coating. Afterwards, the above steps were repeated on the other side of the substrate layer to form a double-sided inorganic coating.
  • the polymer particles with core-shell structure are used, the shell of which is styrene-acrylate copolymer, the core of which is acrylate polymer, the total swelling degree is 450%, and the particle size is 0.45 ⁇ m.
  • the polymer bonding layer glue is made of 25 parts by mass of core-shell structure polymer emulsion (solid content 40%), 40 parts by mass of deionized water and 35 parts by mass of ethanol; the preparation process is: first, 50Kg of deionized water and ethanol solvent are added to a double planetary mixer, and mixed at 25°C for 1 hour; then 16.7Kg of core-shell structure polymer emulsion is added, and dispersed at 45°C for 2 hours to obtain the polymer bonding layer glue.
  • the porous substrate + heat-resistant coating was coated on the surface by gravure roller coating to form a double-sided coating structure.
  • the quality and thickness of the coating on both sides were consistent.
  • the coating speed was 6m/min, the coating amount was adjusted to 0.036mg/ cm2 , and the drying was carried out by three The drying is performed in sections, each section of the oven is 3 m long, and the set temperatures of the oven are 50°C, 60°C, and 60°C; after drying, a polymer bonding layer with a single layer of particle accumulation is obtained.
  • the positive electrode sheet, separator, and negative electrode sheet prepared above are stacked in order, so that the groove of the negative electrode sheet faces the positive electrode sheet, and the separator is placed between the positive electrode sheet and the negative electrode sheet to play a role of isolation, and wound to obtain an electrode assembly, the thickness of which is shown in Table 1.
  • the electrode assembly is placed in an aluminum-plastic film packaging bag, and the electrolyte is injected after drying, and a lithium-ion battery is obtained through vacuum packaging, standing, formation, degassing, trimming and other processes.
  • the polymer particles with core-shell structure are used, the shell of which is styrene-acrylate copolymer, the core of which is acrylate polymer, the total swelling degree is 450%, and the particle size is 0.45 ⁇ m.
  • the polymer bonding layer glue is made of 25 parts by mass of core-shell structure polymer emulsion (solid content 25%), 40 parts by mass of deionized water and 35 parts by mass of ethanol; the preparation process is: first, 50Kg of deionized water and ethanol solvent are added to a double planetary mixer, and mixed at 25°C for 1 hour; then 16.7Kg of core-shell structure polymer emulsion is added, and dispersed at 45°C for 2 hours to obtain the polymer bonding layer glue.
  • the polymer used is polyvinylidene fluoride-hexafluoropropylene copolymer, with a swelling degree of 190% and a particle size of 1.5 ⁇ m.
  • 68Kg of deionized water and 12Kg of PVDF-HFP are added to a double planetary mixer and mixed at 45°C for 6 hours to prepare a polymer adhesive layer glue with a solid content of about 15%.
  • the porous substrate + heat-resistant coating is coated on the surface by rotary spraying to form a double-sided coating.
  • layer structure the quality and thickness of the coating on both sides are consistent;
  • the coating speed is 8m/min, the coating amount is adjusted to 0.16mg/ cm2 , and the drying adopts three-stage drying, each section of the oven is 3m long, and the set temperature of the oven is 50°C, 60°C, and 60°C; after drying, the polymer bonding layer is distributed in islands and lines on the heat-resistant coating, wherein the area of the island coating is 1 ⁇ m to 10mm, and the thickness is 1 ⁇ m to 100 ⁇ m; the width of the linear coating is 1 ⁇ m to 1mm, the length is 1 ⁇ m to 50mm, and the thickness is 1 ⁇ m to 100 ⁇ m.
  • a polypropylene film with a thickness of 9 ⁇ m was used.
  • Polyvinylidene fluoride and aluminum oxide ceramic particles were mixed at a mass ratio of 60:40, NMP was added as a solvent, and a bonding layer slurry with a solid content of 75wt% was prepared and stirred evenly.
  • the bonding layer slurry was coated on the surface of one substrate layer and dried at 90°C to obtain a bonding layer, and the thickness of the bonding layer was shown in Table 1. Thereafter, the above steps were repeated on the surface of the other substrate layer to form a double-sided coated bonding layer (i.e., the first bonding layer) to obtain a diaphragm.
  • Example 1 Except that ⁇ Preparation of negative electrode sheet> is different from Example 1, the rest is the same as Example 1.
  • the slurry was evenly coated on one surface of a negative electrode current collector copper foil with a thickness of 6 ⁇ m, and dried at 85°C to obtain a negative electrode sheet with a negative electrode active material layer thickness of 50 ⁇ m; then, the above steps were repeated on the other surface of the negative electrode sheet to obtain a negative electrode sheet with negative electrode active materials coated on both sides, and then after striping and cutting, it was dried at 110°C under vacuum for 4 hours, and the tabs were welded to obtain a negative electrode sheet.
  • the groove width, groove spacing, cross-sectional area, and porosity of the negative electrode sheet will generally also affect the performance of the lithium-ion battery. It can be seen from Examples 1 to 22 and Comparative Example 4 that, when H ⁇ T+1 is satisfied, by regulating the above parameters within the scope of this application, a lithium-ion battery with excellent cycle stability and safety at high temperature can be obtained.
  • the type of polymer in the bonding layer will generally also affect the performance of the lithium-ion battery. It can be seen from Examples 19, 22, and 28 to 31 that, when H ⁇ T+1 is satisfied, by regulating the above parameters within the scope of this application, a lithium-ion battery with excellent cycle stability and safety at high temperatures can be obtained.

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Abstract

本申请提供了一种二次电池和电子装置，二次电池包括电极组件，电极组件包括正极极片、负极极片和隔膜，隔膜设置于正极极片和所述负极极片之间，负极极片包括负极集流体和负极活性材料层，其中，负极活性材料层与正极极片相对的表面具有凹槽，凹槽的深度为Hμm；隔膜包括基材层和粘结层，粘结层的厚度为Tμm，满足：H≥T+1。本申请通过调控凹槽的深度与粘结层的厚度满足本申请范围，从而能够增加二次电池内部的散热能力，提高二次电池的高温性能。

Description

一种二次电池和电子装置 技术领域
本申请涉及电化学技术领域，特别是涉及一种二次电池和电子装置。
背景技术
二次电池，如锂离子电池具有比能量大、工作电压高、自放电率低、体积小、重量轻等特点，在消费电子领域具有广泛的应用。随着锂离子电池的广泛应用，市场对锂离子电池的性能提出了越来越高的要求。
锂离子电池在反复充放电循环过程中，会在其内部积累应力引起变形，从而导致锂离子电池出现厚度超规格、循环衰减加速等问题，影响锂离子电池的循环稳定性。另外，随着锂离子电池在循环过程中热量在内部累积，如果热量不能及时散出，将增加热失控风险，影响锂离子电池的安全性。
发明内容
本申请的目的在于提供一种具有良好的循环稳定性和安全性的二次电池和电子装置。
需要说明的是，在申请内容中，以锂离子电池作为二次电池的例子来解释本申请，但是本申请的二次电池并不仅限于锂离子电池。具体技术方案如下：
本申请第一方面提供了一种二次电池，其包括电极组件，所述电极组件包括正极极片、负极极片和隔膜，所述隔膜设置于所述正极极片和所述负极极片之间，所述负极极片包括负极集流体和负极活性材料层，其中，所述负极活性材料层与所述正极极片相对的表面具有凹槽，所述凹槽的深度为Hμm；所述隔膜包括基材层和设置于所述隔膜与所述负极极片相对的表面的粘结层，所述粘结层的厚度为Tμm，满足：H≥T+1。优选地，H≥T+5。本申请通过调控凹槽的深度与粘结层的厚度满足本申请范围，能够提升凹槽对电解液以及高温条件下产生的高温气体的传导效果，从而能够增加二次电池内部的散热能力，提高二次电池的高温性能。
在本申请的一些实施方案中，所述凹槽的截面面积为A μm2，所述凹槽的宽度为W μm，满足：0.35×(W×H)<A<0.95(W×H)，5≤H≤100。优选地，0.55×(W×H)<A<0.85(W×H)。通过调整凹槽的截面面积可以实现对凹槽处界面形貌的调整，从而在高温热箱条件下进一 步改善极片的界面热量分散效果，改善锂离子电池内部的散热能力，提高锂离子电池高温下的循环稳定性和安全性。
在本申请的一些实施方案中，1≤W/H≤40。优选地，2≤W/H≤20，能够进一步改善锂离子电池内部的散热能力，提高锂离子电池高温下的循环稳定性和安全性。
在本申请的一些实施方案中，所述凹槽的宽度为Wμm，所述凹槽的间距为Sμm，所述负极极片的孔隙率为P％，满足：优选地，调整负极极片孔隙率、凹槽宽度及凹槽间距满足上述关系，能够有效改善高温条件下极片的热量平衡，提升极端环境下的热扩散效率，降低锂离子电池的热失控风险，提高锂离子电池的安全性能，并且还能够通过凹槽提供的空间释放锂离子电池高温循环过程中内部产生的应力，从而改善锂离子电池循环变形问题，提高锂离子电池的循环稳定性。
在本申请的一些实施方案中，所述凹槽的间距为Sμm，所述隔膜与所述负极极片之间的粘结力为F N/m，满足：S≤1000F，500≤S≤10000，优选地，S≤650F。能够改善锂离子电池内部的散热能力，降低锂离子电池的热失控风险，提高锂离子电池的安全性能。
在本申请的一些实施方案中，0.1≤T≤10。通过调控粘结层的厚度在上述范围，有利于提升隔膜与包括凹槽的极片的粘结性能，从而提高锂离子电池的安全性能。
在本申请的一些实施方案中，所述粘结层包括聚合物，基于所述粘结层的质量，所述聚合物的含量为25％至100％，优选地，聚合物的含量为30％至100％，进一步优选地，聚合物的含量为50％至100％。通过调控聚合物的含量在上述范围内，有利于隔膜界面粘结力的提高，从而改善锂离子电池的变形问题，提高锂离子电池在高温下的循环稳定性和安全性。
在本申请的一些实施方案中，所述隔膜与所述负极极片之间的粘结力为F N/m，满足：1≤F≤50。优选地，5≤F≤30。进一步优选地，7≤F≤30。通过调控隔膜与负极之间的粘结力在上述范围内，能够改善锂离子电池循环变形问题，提高锂离子电池的循环稳定性。
在本申请的一些实施方案中，所述聚合物包括聚偏氟乙烯、聚偏氟乙烯-六氟丙烯共聚 物、苯乙烯-丁二烯共聚物、聚丙烯腈、丁二烯-丙烯腈聚合物、聚丙烯酸、聚丙烯酸酯或丙烯酸酯-苯乙烯共聚物中的至少一种。
在本申请的一些实施方案中，所述负极极片还包括负极极耳，沿所述负极极耳的长度方向设置有第一凹槽部，且沿所述负极极耳的长度方向，所述第一凹槽部与所述负极极耳之间设置有所述负极活性材料层；其中，所述第一凹槽部与所述负极极耳的距离为d mm，0.2＜d＜5。一方面能够优化高温条件下的热量分散效果，另一方面由于沿负极极耳的长度方向凹槽与极耳区域之间负极活性材料层的保留，能够进一步改善极耳区域的离子传导，改善区域电化学界面，从而提升二次电池的循环性能，同时，凹槽与极耳区域的分离设计，能够避免对集流体局部区域的二次加工，提高提高负极极片良品率。
本申请第二方面提供了一种电子装置，其包括前述实施方案所述的二次电池。由此，电子装置具有良好的高温循环稳定性和安全性。
本申请提供的一种二次电池和电子装置，其中，负极活性材料层与正极极片相对的表面具有凹槽，凹槽的深度为Hμm；隔膜包括基材层和设置于隔膜与负极极片相对的表面的粘结层，所述粘结层的厚度为Tμm，满足：H≥T+1。本申请通过调控凹槽的深度与粘结层的厚度满足本申请范围，从而能够增加二次电池内部的散热能力，提高二次电池的高温性能。
附图说明
此处所说明的附图用来提供对本申请的进一步理解，构成本申请的一部分，本申请的示意性实施例及其说明用于解释本申请，并不构成对本申请的不当限定。
图1为本申请一些实施方案中电极组件的结构示意图；
图2为本申请一些实施方案中电极组件沿自身厚度方向的局部剖面结构示意图；
图3为本申请一些实施方案中负极极片沿自身厚度方向的局部剖面结构示意图；
图4为本申请一些实施方案中负极极片沿自身厚度方向的局部俯视图；
图5为本申请一些实施方案中隔膜沿自身厚度方向的剖面结构示意图；
图6为本申请另一些实施方案中隔膜沿自身厚度方向的剖面结构示意图；
图7为本申请一些实施方案中负极极片的结构示意图；
图8为本申请一些实施方案中凹槽轮廓确定及凹槽参数测量示意图。
附图标记：10-电极组件，20-正极极片，21-正极集流体，22-正极活性材料层，30-负
极极片，31-负极集流体，32-负极活性材料层，33-负极极耳，34-空箔区，40-隔膜，41-基材层，42-无机涂层，43-粘结层，321-凹槽，322-第一凹槽部。
具体实施方式
为使本申请的目的、技术方案、及优点更加清楚明白，以下参照附图并举实施例，对本申请进一步详细说明。显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员所获得的所有其他实施例，都属于本申请保护的范围。
需要说明的是，在具体实施方式中，以锂离子电池作为二次电池的例子来解释本申请，但是本申请的二次电池并不仅限于锂离子电池。具体技术方案如下：
本申请第一方面提供了一种二次电池，如图1所示，其包括电极组件10，其中，X方向为电极组件10自身长度方向，Y方向为电极组件10自身宽度方向，Z方向为电极组件10自身厚度方向。如图2所示，电极组件10包括正极极片20、负极极片30和隔膜40，隔膜40设置于正极极片20和负极极片30之间，正极极片20包括正极集流体21和正极活性材料层22，负极极片30包括负极集流体31和负极活性材料层32，其中，负极活性材料层32与正极极片20相对的表面具有凹槽321。如图3所示，凹槽的深度为Hμm。如图5所示，隔膜40包括基材层41和粘结层43，粘结层的厚度为Tμm，满足：H≥T+1，优选地，H≥T+5。本申请中，粘结层43可以为隔膜40与负极极片30相对的表面层。
锂离子电池制备过程中，由于外部的压力和电极组件内部膨胀产生的压力共同作用，隔膜的粘结层中的聚合物被压缩从而产生粘结效果。在凹槽处粘结层受力后与凹槽产生局部粘结作用，但是，过厚的粘结层会改变高温条件下电极组件内部的热量分布，同时影响凹槽对热量的分散效果，从而影响对高温热箱的改善效果。发明人研究发现，本申请通过调控凹槽的深度与粘结层的厚度满足本申请范围，能够提升凹槽对高温条件下产生的高温热量的分散效果，从而改善锂离子电池内部的散热能力，提高锂离子电池的高温性能，例如提高锂离子电池高温下的循环稳定性和安全性。本申请中，负极活性材料层32可以单面设置，也可以双面设置。
在本申请的一些实施方案中，凹槽的截面面积为A μm2，凹槽的宽度为Wμm，满足： 0.35×(W×H)<A<0.95(W×H)，5≤H≤100。优选地，0.55×(W×H)<A<0.85(W×H)。通过调控C、W与H之间满足上述关系，并协同调控H在上述范围，可以实现对凹槽处界面形貌的调整，从而在高温热箱条件下进一步改善极片的界面热量分散效果，改善锂离子电池内部的散热能力，同时改善凹槽处隔离膜粘接层与极片的电化学接合，提高锂离子电池高温下的循环稳定性和安全性。
在本申请的一些实施方案中，1≤W/H≤40。优选地，2≤W/H≤20。通过进一步调控W与H之间满足上述关系，能够进一步改善锂离子电池内部的散热能力，提高锂离子电池高温下的循环稳定性和安全性。
在本申请的一些实施方案中，如图3和图4所示，凹槽的宽度为Wμm，凹槽的间距为Sμm，负极极片的孔隙率为P％，满足：优选地，发明人研究发现，高温热箱失效主要是由于负极极片活性材料层表面与电解液接触，在高温条件下发生副反应，副反应产生的热量在电池内部累积，热失控风险增加。而当负极极片的孔隙率越大，负极活性材料层与电解液接触的面积越大，产热量越多，热失控风险越大。并且，低孔隙率的负极极片其膨胀空间较小，锂离子电池会由于膨胀导致变形问题。基于此，本申请通过调控凹槽的宽度、凹槽的间距、负极极片的孔隙率满足上述关系，能够提升凹槽对高温热箱条件下产生的热量的分散效果，提升极端环境下的热扩散效率，降低锂离子电池的热失控风险，提高锂离子电池的安全性能，并且还能够通过凹槽有效分散高温循环过程中的产气，改善隔膜与极片之间的界面电化学性能，提高锂离子电池的高温循环稳定性。
在本申请的一些实施方案中，锂离子电池的负极极片满足5≤P≤50。优选地，10≤P≤40。进一步优选地，10≤P≤30。通过调控上述参数在本申请范围内，有利于得到具有良好高温循环稳定性和安全性的锂离子电池。
在本申请的一些实施方案中，如图3和图4所示，凹槽的间距为Sμm，隔膜与负极极片之间的粘结力为F N/m，满足：S≤1000F，500≤S≤10000，优选地，S≤650F。发明人研究发现，不同类型的隔膜其界面粘结性能不同，高粘结性能隔膜对锂离子电池的变形改善效果好，但散热效果会降低。基于此，本申请通过调控上述S与F之间满足上述关系，针对 粘结性能不同的隔膜，也能够提升凹槽对高温热箱条件下产生的高温气体的传导效果，从而改善锂离子电池内部的散热能力，降低锂离子电池的热失控风险，提高锂离子电池的安全性能。
在本申请的一些实施方案中，0.1≤T≤10。通过调控粘结层的厚度在上述范围，有利于提升隔膜与包括凹槽的极片的粘结性能，从而提高锂离子电池的安全性能。
所述粘结层中包括聚合物；其中，基于所述粘结层的质量，所述聚合物的含量为25％至100％，优选地，聚合物的含量为30％至100％，通过调控聚合物的含量在上述范围内，有利于隔膜界面粘结力的提高，从而改善锂离子电池的变形问题，提高锂离子电池在高温下的循环稳定性和安全性。
在本申请的一些实施方案中，如图5所示，粘结层43位于基材层41的表面，粘结层43包括聚合物和无机材料。通过上述结构设计和材料选择的协同作用，有利于隔膜界面粘结力的提高，从而改善锂离子电池的变形问题，提高锂离子电池在高温下的循环稳定性和安全性。
在本申请的一些实施方案中，如图6所示，隔膜还包括无机涂层42，无机涂层42位于基材层41和粘结层43之间，无机涂层42中包括无机材料，粘结层43包括聚合物。通过上述结构设计和材料选择的协同作用，有利于隔膜界面粘结力的提高，从而改善锂离子电池的变形问题，提高锂离子电池在高温下的循环稳定性和安全性。
在本申请的一些实施方案中，1≤F≤50。优选地，5≤F≤30。进一步优选地，7≤F≤30。通过调控隔膜与负极之间的粘结力在上述范围内，能够改善锂离子电池循环变形问题，提高锂离子电池的循环稳定性。
在本申请的一些实施方案中，聚合物包括聚偏氟乙烯、聚偏氟乙烯-六氟丙烯共聚物、苯乙烯-丁二烯共聚物、聚丙烯腈、丁二烯-丙烯腈聚合物、聚丙烯酸、聚丙烯酸酯或丙烯酸酯-苯乙烯共聚物中的至少一种。当隔膜包含上述聚合物时，有利于提高隔膜的界面粘结性能。
参考图7，负极极耳33通常焊接在负极极片30的空箔区34(负极极片中未涂覆负极 活性材料的区域)，发明人研究发现，在锂离子电池循环过程中，负极极耳处容易出现热量积聚问题，影响锂离子电池散热。在本申请的一些实施方案中，如图7所示，负极极片30还包括负极极耳33，凹槽321沿负极极耳33的长度方向(即Y方向)设置，沿负极极耳33的长度方向设置有第一凹槽部322，且沿负极极耳33的长度方向，第一凹槽部322与负极极耳33之间设置有负极活性材料层；其中，第一凹槽部322与负极极耳33的距离为d mm，0.2＜d＜5。本申请通过上述结构，一方面能够优化高温条件下的热量分散效果，另一方面由于沿负极极耳的长度方向凹槽与极耳区域之间负极活性材料层的保留，能够进一步改善极耳区域的离子传导，改善区域电化学界面，从而提升二次电池的循环性能，同时，凹槽与极耳区域的分离设计，能够避免对集流体局部区域的二次加工，提高负极极片良品率。
可以理解的是，本申请的电极组件可以为卷绕结构，其电极极片展开后通常具有长边和短边。在本申请的一种实施方案中，电极组件为卷绕结构，则宽度方向为电极极片展开后短边的延伸方向，长度方向为电极极片展开后长边的延伸方向。本申请的电极极片包括正极极片20和负极极片30。
本申请的二次电池可以包括发生电化学反应的任何装置，只要能够实现本申请目的即可。例如，二次电池可以包括但不限于：锂离子二次电池(锂离子电池)、钠离子二次电池、锂聚合物二次电池或锂离子聚合物二次电池等。本申请的电池结构包括但不限于软包型电池、方形硬壳电池或圆柱形硬壳电池等。
本申请对负极集流体没有特别限制，只要能够实现本申请目的即可。例如，负极集流体可以包含铜箔、铜合金箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜或复合集流体等。本申请对负极集流体的厚度没有特别限制，只要能够实现本申请目的即可。例如，负极集流体的厚度为4μm至10μm。在本申请中，负极活性材料层可以设置于负极集流体厚度方向上的一个表面上，也可以设置于负极集流体厚度方向上的两个表面上。需要说明，这里的“表面”可以是负极集流体的全部区域，也可以是负极集流体的部分区域，本申请没有特 别限制，只要能实现本申请目的即可。
本申请对负极活性材料的种类没有特别限制，只要能够实现本申请目的即可。例如，负极活性材料可以包含石墨，石墨与硅、氧化硅或碳化硅等硅材料的混合物，上述石墨可以选自人造石墨或天然石墨。任选地，负极活性材料层还包括导电剂、增稠剂、粘结剂中的至少一种。本申请对负极活性材料层中的导电剂、增稠剂和粘结剂的种类没有特别限制，只要能够实现本申请目的即可。例如，负极粘结剂可以包括但不限于聚乙烯醇、羧甲基纤维素、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏1,1-二氟乙烯、聚乙烯、聚丙烯、聚丙烯酸、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂或尼龙中的至少一种。本申请对负极活性物质层中负极活性物质、导电剂、增稠剂和粘结剂的质量比没有特别限制，只要能够实现本申请目的即可。例如，负极活性物质层中负极活性物质、导电剂、增稠剂和粘结剂的质量比为(96～98)∶(0～1.5)∶(0.5～1.5)∶(1.0～1.9)。
本申请对隔膜基材层的材料没有特别限制，本领域技术人员可以根据实际需要选择，只要能够实现本申请目的即可。例如，隔膜基材层的材料可以包括但不限于聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯或聚酰亚胺等中的至少一种。任选地，可以使用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。
本申请的二次电池还包括电解液，本申请对电解液没有特别限制，本领域技术人员可以根据实际需要选择，只要能够实现本申请目的即可。例如，将碳酸亚乙酯(也称碳酸乙烯酯，简写EC)、碳酸亚丙酯(PC)、碳酸二乙酯(DEC)、丙酸乙酯(EP)、丙酸丙酯(PP)碳酸甲乙酯(EMC)、碳酸二甲酯(DMC)、碳酸亚乙烯酯(VC)或碳酸氟代亚乙酯(FEC)等中的至少一种按照一定质量比例混合得到非水有机溶剂后，加入锂盐溶解并混合均匀即可。本申请对上述“质量比例”没有特别限制，只要能够实现本申请目的即可。本申请对锂盐的种类没有限制，只要能够实现本申请目的即可。例如，锂盐可以包括LiPF6、LiBF4、LiAsF6、LiClO4、LiB(C6H5)4、LiCH3SO3、LiCF3SO3、LiN(SO2CF3)2、LiC(SO2CF3)3、LiSiF6、 二草酸硼酸锂(LiBOB)或二氟硼酸锂中的至少一种。本申请对锂盐在电解液中的浓度没有特别限制，只要能够实现本申请目的即可。例如，锂盐的浓度为1.0mol/L至2.0mol/L。
本申请的正极极片可以包括正极活性材料层和正极集流体。本申请对正极活性材料的种类没有特别限制，只要能够实现本申请目的即可。例如，正极活性材料可以包含镍钴锰酸锂、镍钴铝酸锂、磷酸铁锂、富锂锰基材料、钴酸锂、锰酸锂或磷酸锰铁锂等中的至少一种。在本申请中，正极活性材料还可以包含非金属元素，例如非金属元素包括氟、磷、硼、氯、硅或硫等中的至少一种，这些元素能进一步提高正极活性材料的稳定性。本申请的正极活性材料层还可以包括导电剂、粘结剂。本申请对正极活性材料层中正极活性材料、导电剂、粘结剂的质量比没有特别限制，本领域技术人员可以根据实际需要选择，只要能够实现本申请目的即可。例如，正极活性材料层中正极活性材料、导电剂和粘结剂的质量比为(96～98)∶(1～3)∶(2～3)。
本申请对正极集流体没有特别限制，只要能够实现本申请目的即可。例如，正极集流体可以包含铝箔、铝合金箔或复合集流体等。本申请对正极集流体的厚度没有特别限制，只要能够实现本申请目的即可。例如，正极集流体的厚度为5μm至20μm。在本申请中，正极活性材料层可以设置于正极集流体厚度方向上的一个表面上，也可以设置于正极集流体厚度方向上的两个表面上。需要说明，这里的“表面”可以是正极集流体的全部区域，也可以是正极集流体的部分区域，本申请没有特别限制，只要能实现本申请目的即可。
本申请对负极极片的制备方法没有特别限制，只要能够实现本申请目的即可。例如，负极极片的制备方法包括但不限于如下步骤：将负极活性材料、导电剂、增稠剂和粘合剂分散于去离子水中混合，形成均匀的负极浆料，将负极浆料涂覆在负极集流体上，经烘干、冷压后，再在负极极片的表面制备凹槽，再经裁片、分切工序后，得到如图3所示结构的负极极片。
本申请对正极极片的制备方法没有特别限制，只要能够实现本申请目的即可。例如，正极极片的制备方法包括但不限于如下步骤：将正极活性材料、导电剂和粘合剂分散于 NMP溶剂中混合，形成均匀的正极浆料，将正极浆料涂覆在正极集流体上，经烘干、冷压、裁片、分切，得到正极极片。
本申请对凹槽的形状没有特别限制，只要能够实现本申请目的即可。例如，从负极极片的长度方向观察，凹槽的形状可以包括正方形、长方形、梯形、三角形或半圆形中的至少一种；从负极极片的厚度方向观察，凹槽的形状包括直线形、斜线形、折线形或曲线形中的至少一种。
本申请对制备凹槽的方法没有特别限制，只要能够实现本申请目的即可。例如，可以包括但不限于激光刻蚀加工、机械加工或造孔剂加工。以激光刻蚀加工为例，凹槽的宽度和深度通常随激光的功率增加而增加，凹槽的间距通常可以通过激光的加工速率调整，因此，技术人员可以通过调整激光的功率、加工速率和极片的走带速率等参数来调整凹槽的宽度、深度、间距等参数。
负极极片的孔隙率通常随负极极片的压实密度增大而降低，基于此，可以通过调整负极极片的冷压压力，调节负极极片的压实密度，从而调整负极极片的孔隙率。
本申请对二次电池的制备方法没有特别限制，可以选用本领域公知的制备方法，只要能够实现本申请目的即可。例如，二次电池的制备方法包括但不限于如下步骤：将正极极片、隔膜和负极极片按顺序堆叠，并根据需要将其卷绕、折叠等操作得到卷绕结构的电极组件，将电极组件放入包装袋内，将电解液注入包装袋并封口，得到二次电池。
本申请第二方面提供了一种电子装置，其包括前述实施方案所述的二次电池。由此，电子装置具有良好的循环稳定性和安全性。
本申请对电子装置没有特别限制，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括但不限于笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、 自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池或锂离子电容器等。
实施例
以下，举出实施例及对比例来对本申请的实施方式进行更具体地说明。各种的试验及评价按照下述的方法进行。
测试方法和设备：
负极极片与隔膜间粘接力F测试：
截取宽度×长度＝15mm×60mm的粘结有隔膜的负极极片，使用宽度×长度＝20mm×100mm的双面胶，将样品固定在钢板上，测试面朝下。将宽度与样品等宽，长度大于样品长度150mm的纸带一端插入样品下方，并且用皱纹胶固定。将钢板固定在高铁拉力机底部，将上述纸带另一端固定在高铁拉力机上夹具，启动高铁拉力机。待拉力稳定后，拉力数据即为粘结力。
粘结层厚度测试：
选择电极组件中未与正极活性材料层或负极活性材料层相对设置的隔膜部分，通过离子束剖面研磨(CP)制作隔膜截面，然后通过扫描电镜(ZEISS Sigma/X-max)对粘结层的厚度进行测量。
凹槽深度H、凹槽宽度W、凹槽间距S、凹槽的截面面积A测量：
使用型号为VK-1050的激光共聚焦显微镜，对凹槽区域进行拍摄，获取显微镜视野范围内极片的光学和深度信息。在20倍放大倍率下，使用激光共焦模式扫描极片表面，待扫描完毕后，在仪器关联的数据分析软件中对获取到的测量数据进行处理，利用“处理图像”中的“基准面设置”功能对测量数据进行基准面设置，接着选用“平滑”功能，选择“5×5”大小、“简单平均”类型，对图形进行平滑处理，处理完成后，利用“轮廓测量”功能进行凹槽参数的测量。
凹槽深度H和凹槽宽度W：如图8所示，凹槽最深处与基准面的深度差即为凹槽深度， 凹槽两侧与基准面的交点之间的距离即为凹槽的宽度。沿同一凹槽，每间隔10μm进行一次测量，共测量20次，计算20次的深度和宽度的平均值，记录凹槽深度H和宽度W。
凹槽间距S：对于相邻凹槽(沿极片长度方向观察，处于邻位的两条凹槽重合部分大于各自长度的50％，则为相邻凹槽)，在凹槽的垂直方向上，两条凹槽宽度中点的距离即为凹槽的间距。沿选定凹槽，每间隔10μm进行一次测量，共测量20次，计算平均值，记为凹槽间距S。
凹槽面积A：使用型号为VK-1050的激光共聚焦显微镜，对凹槽区域进行拍摄，获取显微镜视野范围内极片的光学和深度信息。在20倍放大倍率下，使用激光共焦模式扫描极片表面，扫描完毕，获得每个像素宽度上相对于基准线的深度数据。在上述凹槽宽度范围内，对每个像素宽度(w0)上的深度(hi)进行积分，即为凹槽的截面积A：
A＝∑ihi×w0。
负极极片孔隙率测试：
采用气体置换法测试负极极片的孔隙率：采用同一模具冲切50片半径为d的负极极片，测量每片负极极片的厚度h，并将50片负极极片装入测试设备(AccuPycП1340)的样品杯中，在密闭的样品仓中采用氦气对负极极片进行填充，由此测得负极极片的真体积V，然后通过如下公式计算负极极片的孔隙率：(1-V/πd2×50×h)×100％。
锂离子电池的高温容量保持率和高温厚度膨胀率测试：
在45℃下，将锂离子电池以0.7C倍率恒流充电至电压为4.5V，之后以4.5V恒压充电至电流为0.05C，然后以1C倍率恒流放电至电压为3.0V，以此为一个充放电循环过程；反复400次充放电循环后，测试锂离子电池的高温容量保持率和高温厚度膨胀率。
锂离子电池400次循环后的容量保持率＝第400次循环后的放电容量/第一次循环后的放电容量×100％；
锂离子电池400次循环后的厚度膨胀率＝第400次循环后的锂离子电池厚度/第一次循环时的锂离子电池厚度×100％。
锂离子电池热箱通过率测试：
将锂离子电池放置在密封的温控箱内，在25℃下，以0.7C倍率恒流充电至电压为4.5V，之后以4.5V恒压充电至电流为0.05C，随后将温控箱以(5±2)℃/min升温，当温度达到135℃后恒温60min。待温控箱自然冷却后，观察锂离子电池是否起火爆炸，锂离子电池不起火、不爆炸即为通过。每个实施例或对比例测试10个锂离子电池，记录通过热箱电池个数n，记为n/10。
实施例1
<负极极片的制备>
将人造石墨、导电炭黑(SP)、羧甲基纤维素钠(CMC)、丁苯橡胶(SBR)按照质量比96.5∶1∶1∶1.5混合，加入去离子水，调配成为固含量为75wt％的浆料，并搅拌均匀。将浆料均匀涂覆在厚度为6μm的负极集流体铜箔的一个表面上，在85℃条件下烘干，得到负极活性材料层厚度为50μm的负极极片；之后，在该负极极片的另一个表面上重复以上步骤，即得到双面涂布负极活性材料的负极极片；然后将上述得到的负极极片进行冷压后，通过激光加工技术在负极活性材料层的表面刻蚀凹槽，再经分条、裁切后，清洗得到极耳焊接区域，焊接极耳得到负极极片。凹槽深度H、凹槽宽度W、凹槽间距S、凹槽的截面面积、负极极片的孔隙率等参数如表1所示。
<正极极片的制备>
将钴酸锂、聚偏氟乙烯、导电剂Super P按质量比96︰2︰2混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成为固含量为75wt％的浆料，并搅拌均匀。将浆料均匀涂覆在厚度为6μm的正极集流体铝箔的一个表面上，95℃条件下烘干，得到正极活性材料层厚度为60μm的正极极片；之后，在该正极极片的另一个表面上重复以上步骤，即得到双面涂布正极活性物质的正极极片；然后将上述得到的正极极片进行冷压、分条、裁切后在真空条件下85℃烘干4小时，再焊接极耳得到正极极片。
<电解液的制备>
将碳酸亚乙酯、碳酸二乙酯、甲基乙基碳酸酯和亚乙烯基碳酸酯按照质量比为8∶85∶5∶2混合得到非水有机溶剂。然后将锂盐LiPF6与得到的上述非水有机溶剂按照质量比8∶92配制得到电解液。
<隔膜的制备>
<基材层的制备>
采用厚度为5μm的聚丙烯薄膜。
<无机涂层的制备>
三氧化二铝陶瓷颗粒、丁二烯-苯乙烯聚合物、去离子水质量比为35：10：55。将丁二烯-苯乙烯聚合物和去离子水共30Kg加入到容积为60L的双行星搅拌机中，在45℃下分散3小时；再将三氧化二铝陶瓷粉体16.1Kg加入到搅拌机中，在45℃下高速分散2小时；然后采用纳米研磨机进行球磨，时间为1.5小时，所采用的研磨介质为直径6μm的球形氧化锆珠，得到无机涂层胶液。
采用转移涂布方式对基材进行表面涂布，其中涂布速度为6m/min，涂覆量调控为0.18mg/cm2，涂布厚度为1.5μm；采用三段烘干方式，每段烘箱长度为3m，烘箱的设定温度为50℃、60℃、60℃，形成包括单面无机涂层的基材层。之后，在基材层的另一侧表面重复以上步骤，形成双面涂覆的无机涂层。
<粘结层的制备>
采用具有核壳结构的聚合物颗粒，其外壳为苯乙烯-丙烯酸酯共聚物，内核为丙烯酸酯聚合物，总溶胀度450％，粒径为0.45μm。聚合物粘结层胶液由25质量份的核壳结构聚合物乳液(固含量40％)、40质量份的去离子水和35质量份的乙醇制成；制备过程是：先将去离子水和乙醇溶剂共50Kg加入到双行星搅拌机中，在25℃下混合1小时；然后再加入16.7Kg的核壳结构聚合物乳液，在45℃下分散2小时，得到聚合物粘结层胶液。
采用凹版辊涂方式对多孔基材+耐热涂层进行表面涂布，形成双面涂层结构，两面涂层的质量和厚度均保持一致；涂布速度为6m/min,涂覆量调控为0.036mg/cm2，烘干采用三 段烘干，每段烘箱长度为3m，烘箱的设定温度为50℃、60℃、60℃；干燥后得到单层颗粒堆积的聚合物粘结层。
<锂离子电池的制备>
将上述制备得到的正极极片、隔膜、负极极片按顺序叠好，使负极极片的凹槽面对正极极片，并使隔膜处于正极极片和负极极片中间起到隔离的作用，卷绕得到电极组件，电极组件厚度如表1所示。将电极组件置于铝塑膜包装袋中，干燥后注入电解液，经过真空封装、静置、化成、脱气、切边等工序得到锂离子电池。
实施例2至实施例18、实施例20至实施例21、实施例23至实施例27
在<负极极片的制备>中，各参数在实施例1基础上按照表2调整。
实施例19和实施例22
除了在<隔膜的制备>中调整粘结层胶液的制备以外，其余参数在实施例1基础上按照表2调整。
采用具有核壳结构的聚合物颗粒，其外壳为苯乙烯-丙烯酸酯共聚物，内核为丙烯酸酯聚合物，总溶胀度450％，粒径为0.45μm。聚合物粘结层胶液由25质量份的核壳结构聚合物乳液(固含量25％)、40质量份的去离子水和35质量份的乙醇制成；制备过程是：先将去离子水和乙醇溶剂共50Kg加入到双行星搅拌机中，在25℃下混合1小时；然后再加入16.7Kg的核壳结构聚合物乳液，在45℃下分散2小时，得到聚合物粘结层胶液。
实施例28
除了在<隔膜的制备>中调整粘结层胶液的制备及粘结层的制备以外，其余参数在实施例1基础上按照表2调整。
粘结层胶液的制备：聚合物采用聚偏氟乙烯-六氟丙烯共聚物，溶胀度为190％，粒径为1.5μm。将68Kg去离子水和12Kg的PVDF-HFP加入到双行星搅拌机中，在45℃下混合6小时，配制得到固含量约为15％的聚合物粘结层胶液。
粘结层的制备：采用旋转喷雾方式对多孔基材+耐热涂层进行表面涂布，形成双面涂 层结构，两面涂层的质量和厚度均保持一致；涂布速度为8m/min，涂覆量调控为0.16mg/cm2，烘干采用三段烘干，每段烘箱长度为3m，烘箱的设定温度为50℃、60℃、60℃；干燥后，聚合物粘结层在耐热涂层上呈岛状和线状分布，其中，岛状涂层的面积为1μm至10mm，厚度为1μm至100μm；线状涂层的宽度为1μm至1mm，长度为1μm至50mm，厚度为1μm至100μm。
实施例29至实施例31
除了调整<隔膜的制备>以外，其余参数在实施例1基础上按照表2调整。
<隔膜的制备>：
<基材层的制备>
采用厚度为9μm的聚丙烯薄膜。
<粘结层的制备>
将聚偏氟乙烯和三氧化二铝陶瓷颗粒按质量比60∶40混合，加入NMP作为溶剂，调配成为固含量为75wt％的粘结层浆料，并搅拌均匀。将粘结层浆料涂覆在一面基材层的表面上，90℃条件下烘干，得到粘结层，粘结层厚度如表1所示。之后，在另一面基材层的表面重复以上步骤，形成双面涂覆的粘结层(即第一粘结层)，得到隔膜。
对比例1
除了<负极极片的制备>与实施例1不同以外，其余与实施例1相同。
<负极极片的制备>
将人造石墨、导电炭黑(SP)、羧甲基纤维素钠(CMC)、丁苯橡胶(SBR)按照质量比96.5∶1∶1∶1.5混合，加入去离子水，调配成为固含量为75wt％的浆料，并搅拌均匀。将浆料均匀涂覆在厚度为6μm的负极集流体铜箔的一个表面上，在85℃条件下烘干，得到负极活性材料层厚度为50μm的负极极片；之后，在该负极极片的另一个表面上重复以上步骤，即得到双面涂布负极活性材料的负极极片，再经分条、裁切后在真空条件下110℃烘干4小时，焊接极耳得到负极极片。
对比例2至对比例3
除了在<负极极片的制备>中，如表1所示调整凹槽深度H和凹槽的截面面积A等制备参数，在<隔膜的制备>中，如表1所示调整粘结层厚度以外，其余与实施例1相同。
对比例4
在<负极极片的制备>中，各参数在实施例29基础上按照表1调整。
表1

注：表1中的“/”表示无相关制备参数。
参见表1，从实施例10至实施例11与对比例1至对比例4可以看出，本申请锂离子电池中，通过使负极活性材料层与正极极片相对的表面具有凹槽，并调控凹槽深度与隔膜粘结层厚度之间的关系在本申请范围内，锂离子电池的热箱通过率明显提高，锂离子电池循环过程后的厚度膨胀率也显著下降，表明本申请方案能够提高锂离子电池内部的散热能力，从而提高锂离子电池的高温下的循环稳定性和安全性。
表2




参见表2及表3，凹槽宽度、凹槽间距、截面面积、负极极片的孔隙率通常也会对锂离子电池的性能产生影响，从实施例1至实施例22和对比例4可以看出，在满足H≥T+1的情况下，通过调控上述参数在本申请范围内，能够得到在高温下具有优异循环稳定性和安全性的锂离子电池。
粘结层中聚合物的类型通常也会对锂离子电池的性能产生影响，通过实施例19、实施例22和实施例28至31可以看出，在满足H≥T+1的情况下，通过调控上述参数在本申请范围内，能够得到在高温下具有优异循环稳定性和安全性的锂离子电池。
需要说明的是，术语“包括”、“包括”或者其任何其他变体意在涵盖非排他性的包括，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括所述要素的过程、方法、物品或者设备中还存在另外的相同要素。
以上所述仅为本发明的较佳实施例，并不用以限制本发明，凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明保护的范围之内。

Claims (16)

  1. 一种二次电池，其包括电极组件，所述电极组件包括正极极片、负极极片和隔膜，所述隔膜设置于所述正极极片和所述负极极片之间，所述负极极片包括负极集流体和负极活性材料层，其中，
    所述负极活性材料层与所述正极极片相对的表面具有凹槽，所述凹槽的深度为Hμm；
    所述隔膜包括基材层和设置于所述隔膜与所述负极极片相对的表面的粘结层，所述粘结层的厚度为Tμm，满足：H≥T+1。
  2. 根据权利要求1所述的二次电池，其中，H≥T+5。
  3. 根据权利要求1所述的二次电池，其中，所述凹槽的截面面积为A μm2，所述凹槽的宽度为Wμm，满足：0.35×(W×H)<A<0.95(W×H)，5≤H≤100。
  4. 根据权利要求3所述的二次电池，其中，1≤W/H≤40，0.55×(W×H)<A<0.85(W×H)。
  5. 根据权利要求3所述的二次电池，其中，2≤W/H≤20。
  6. 根据权利要求1所述的二次电池，其中，所述凹槽的宽度为Wμm，所述凹槽的间距为Sμm，所述负极极片的孔隙率为P％，满足：
  7. 根据权利要求6所述的二次电池，其中，

    10≤P≤40。
  8. 根据权利要求1所述的二次电池，其中，所述凹槽的间距为S μm，所述隔膜与所述负极极片之间的粘结力为F N/m，满足：S≤1000F，500≤S≤10000。
  9. 根据权利要求8所述的二次电池，其中，S≤650F。
  10. 根据权利要求1所述的二次电池，其中，0.1≤T≤10。
  11. 根据权利要求1所述的二次电池，其中，所述粘结层中包括聚合物；
    其中，基于所述粘结层的质量，所述聚合物的含量为25％至100％。
  12. 根据权利要求11所述的二次电池，其中，所述隔膜与所述负极极片之间的粘结力为F N/m，满足：1≤F≤50。
  13. 根据权利要求11所述的二次电池，其中，所述隔膜与所述负极极片之间的粘结力为F N/m，满足5≤F≤30；
    其中，基于所述粘结层的质量，所述聚合物的含量为30％至100％。
  14. 根据权利要求11所述的二次电池，其中，所述聚合物包括聚偏氟乙烯、聚偏氟乙烯-六氟丙烯共聚物、苯乙烯-丁二烯共聚物、聚丙烯腈、丁二烯-丙烯腈聚合物、聚丙烯酸、聚丙烯酸酯或丙烯酸酯-苯乙烯共聚物中的至少一种。
  15. 根据权利要求1所述的二次电池，其中，所述负极极片还包括负极极耳，沿所述负极极耳的长度方向设置有第一凹槽部，且沿所述负极极耳的长度方向，所述第一凹槽部与所述负极极耳之间设置有所述负极活性材料层；
    其中，所述第一凹槽部与所述负极极耳的距离为d mm，0.2＜d＜5。
  16. 一种电子装置，其包括权利要求1至15中任一项所述的二次电池。
PCT/CN2023/074396 2023-02-03 2023-02-03 一种二次电池和电子装置 Ceased WO2024159521A1 (zh)

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CN119069773A (zh) * 2024-09-30 2024-12-03 宁德新能源科技有限公司 一种二次电池和电子装置
CN119153787A (zh) * 2024-08-30 2024-12-17 宁德新能源科技有限公司 二次电池及包含其的电子装置
CN119581565A (zh) * 2024-12-05 2025-03-07 宁德新能源科技有限公司 一种电极组件及电池
CN120089790A (zh) * 2025-01-07 2025-06-03 宁德时代新能源科技股份有限公司 电池单体、电池装置和用电装置
CN120914198A (zh) * 2025-10-10 2025-11-07 深圳好电科技有限公司 一种负极极片及二次电池
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CN120883413A (zh) * 2024-07-26 2025-10-31 宁德新能源科技有限公司 二次电池及电子装置
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