WO2023137673A1 - Ensemble électrode, appareil électrochimique et dispositif électrique - Google Patents

Ensemble électrode, appareil électrochimique et dispositif électrique Download PDF

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Publication number
WO2023137673A1
WO2023137673A1 PCT/CN2022/073054 CN2022073054W WO2023137673A1 WO 2023137673 A1 WO2023137673 A1 WO 2023137673A1 CN 2022073054 W CN2022073054 W CN 2022073054W WO 2023137673 A1 WO2023137673 A1 WO 2023137673A1
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Prior art keywords
positive electrode
negative electrode
electrode
current collector
positive
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PCT/CN2022/073054
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English (en)
Chinese (zh)
Inventor
曹毅
张毅
张草欢
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东莞新能安科技有限公司
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Priority to PCT/CN2022/073054 priority Critical patent/WO2023137673A1/fr
Priority to CN202280004212.XA priority patent/CN115668573A/zh
Publication of WO2023137673A1 publication Critical patent/WO2023137673A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • 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
    • 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
    • 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
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/80—Porous plates, e.g. sintered carriers
    • 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
    • H01M50/538—Connection of several leads or tabs of wound or folded electrode stacks
    • 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
    • H01M50/54—Connection of several leads or tabs of plate-like electrode stacks, e.g. electrode pole straps or bridges
    • 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 application relates to the technical field of energy storage, and in particular, relates to an electrode assembly, an electrochemical device and electrical equipment.
  • energy storage devices are more and more widely used, such as mobile phones, laptop computers, battery cars, electric vehicles, electric aircraft, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools.
  • an electrochemical device generally produces electrical energy through a chemical reaction between the electrode assembly and the electrolyte.
  • both its safety and its performance need to be considered, and the energy density of the electrochemical device directly affects the performance of the electrochemical device. Therefore, how to increase the energy density of electrochemical devices is an urgent technical problem to be solved.
  • Embodiments of the present application provide an electrode assembly, an electrochemical device, and electrical equipment, which can effectively increase the energy density of the electrochemical device.
  • an embodiment of the present application provides an electrode assembly, including a positive electrode, a negative electrode, and a separator, and the separator is arranged between the positive electrode and the negative electrode to isolate the positive electrode and the negative electrode; wherein, the positive electrode includes a multilayer positive electrode sheet that is continuously arranged along the thickness direction of the electrode assembly, and the positive electrode sheet includes a positive electrode porous current collector and a positive electrode active material layer, and the positive electrode active material layer is arranged on the surface of the positive electrode porous current collector; and/or, the negative electrode includes a multilayer negative electrode that is continuously arranged along the thickness direction of the electrode assembly.
  • the negative electrode sheet includes a negative electrode porous current collector and a negative electrode active material layer, and the negative electrode active material layer is arranged on the surface of the negative electrode porous current collector.
  • the multi-layer positive electrode sheet is continuously arranged to form a thick electrode, which increases the thickness of the positive electrode, reduces the amount of the separator, reduces the cost of the separator, and effectively improves the energy density of the electrochemical device.
  • the positive electrode is a thick electrode formed by continuous arrangement of multiple positive electrode sheets, the positive electrode active material layer in each layer of positive electrode sheet is relatively thin, and it is not easy to crack, powder drop, etc.
  • the multilayer negative electrode sheets are continuously arranged to form a thick electrode, which increases the thickness of the negative electrode, reduces the amount of separator, reduces the cost of the separator, and effectively improves the energy density of the electrochemical device.
  • the negative electrode is a thick electrode formed by continuous arrangement of multi-layer negative electrode sheets, the negative electrode active material layer in each layer of negative electrode sheets is relatively thin, so it is not easy to crack and drop powder.
  • the ratio of the active material capacity per unit area of the negative electrode to the active material capacity per unit area of the positive electrode is 1.05-1.3.
  • the number of layers of the positive sheet in the positive electrode is less than the number of layers of the negative sheet in the negative electrode.
  • the number of layers of the positive electrode sheet in the positive electrode is smaller than the number of layers of the negative electrode sheet in the negative electrode, it is beneficial to increase the space for the negative electrode to insert ions (such as lithium ions), so that more ions detached from the positive electrode sheet during charging can be embedded in the negative electrode sheet, which can effectively reduce the occurrence of lithium precipitation.
  • ions such as lithium ions
  • the sum of the thicknesses of the positive sheets in the positive electrode is smaller than the sum of the thicknesses of the negative sheets in the negative electrode.
  • the sum of the thicknesses of the positive electrode sheets in the positive electrode is smaller than the sum of the thicknesses of the negative electrode sheets in the negative electrode, it is beneficial to increase the space for the negative electrode to insert ions (such as lithium ions), so that more ions detached from the positive electrode sheet during charging can be embedded in the negative electrode sheet, which can effectively reduce the occurrence of lithium precipitation.
  • ions such as lithium ions
  • the positive electrode porous current collector is provided with a plurality of through holes, the positive electrode porous current collector includes a first part and a second part arranged along the first direction, the positive electrode active material layer is arranged on the surface of the first part, and the second part of the positive electrode sheet is connected to at least two layers in the positive electrode; The fourth portion of the negative plate is connected.
  • the second parts of at least two layers of positive plates in the positive electrode are connected, and the positive electrode porous current collectors of at least two layers of positive plates are connected in parallel, so that the electron transmission path is greatly shortened, the overall impedance of the electrochemical device is reduced, thereby reducing the temperature rise of charging and discharging, and improving the safety of the electrochemical device.
  • the fourth part of at least two layers of negative plates in the negative electrode is connected, and the negative electrode porous current collectors of at least two layers of negative plates are connected in parallel, so that the electron transmission path is greatly shortened, the overall impedance of the electrochemical device is reduced, thereby reducing the temperature rise of charge and discharge, and improving the safety of the electrochemical device.
  • a plurality of the through holes on the positive electrode porous current collector are arranged in the first part; and/or, a plurality of the through holes in the negative electrode porous current collector are arranged in the third part.
  • the plurality of through holes on the positive electrode porous current collector are arranged in the first part, that is, the second part is not provided with a through hole structure, so as to improve the flow capacity of the second part, ensure the strength of the second part, and improve the firmness after the connection of the two layers of the second part.
  • multiple through holes on the negative electrode porous current collector are arranged in the third part, that is, the fourth part is not provided with a through hole structure, so as to improve the flow capacity of the fourth part, ensure the strength of the fourth part, and improve the firmness of the connection between the two layers of the fourth part.
  • the second parts of the at least two layers of the positive electrode sheets in the positive electrode are welded; and/or, the fourth parts of the at least two layers of the negative electrode sheets in the negative electrode are welded.
  • the second parts of at least two layers of positive electrode sheets in the positive electrode are welded, and the connection method is simple and efficient, ensuring the firmness of the connection of at least two layers of second parts.
  • welding the fourth part of at least two layers of negative electrode sheets in the negative electrode is simple and efficient, and ensures the firmness of the connection of at least two layers of the fourth part.
  • the porosity of the positive electrode porous current collector is 3%-40%; and/or, the porosity of the negative electrode porous current collector is 3%-40%.
  • the porosity of the positive electrode porous current collector is 3%-40%, so that the electrolyte can be kept well transported between the multi-layer positive electrode sheets, while ensuring that the positive electrode porous current collector has sufficient strength.
  • the porosity of the negative electrode porous current collector is greater than or equal to 3%-40%, so that the electrolyte can be kept well transported between the multi-layer negative electrode sheets, while ensuring that the negative electrode porous current collector has sufficient strength.
  • the positive electrode porous current collector includes at least one of metal foam or metal foil with through holes, and/or the negative electrode porous current collector includes at least one of metal foam or metal foil with through holes.
  • both the porous current collector of the positive electrode and the porous current collector of the negative electrode can be metal foam, and the metal foam is a metal material containing foam holes, which has good permeability, ensures efficient transmission of electrolyte between multi-layer positive electrode sheets, and has the advantages of low density and good heat insulation performance.
  • Both the positive electrode porous current collector and the negative electrode porous current collector can also be metal foils with through holes, which have the advantages of simple structure and low production cost.
  • the electrode assembly is a wound structure.
  • the electrode assembly is a laminated structure.
  • the electrode assembly includes multiple layers of the positive electrode, multiple layers of the separator, and multiple layers of the negative electrode, and multiple layers of the positive electrode, multiple layers of the separator, and multiple layers of the negative electrode are stacked to form the laminated structure.
  • multi-layer positive electrodes, multi-layer separators and multi-layer negative electrodes are stacked to form a laminated structure.
  • the electrode assembly of this structure has the advantages of simple molding, low production cost and high energy density.
  • an embodiment of the present application further provides an electrochemical device, including the electrode assembly provided in any one embodiment of the first aspect above.
  • an embodiment of the present application further provides an electrical device, including the electrochemical device provided in any one embodiment of the second aspect above.
  • Fig. 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application.
  • Fig. 2 is the schematic structural diagram of the electrochemical device provided by the embodiment of the present application.
  • Fig. 3 is a schematic structural diagram of an electrode assembly provided by some embodiments of the present application.
  • Fig. 4 is a schematic structural view of the positive electrode sheet shown in Fig. 3;
  • Fig. 5 is a schematic structural view of the negative electrode sheet shown in Fig. 4;
  • Fig. 6 is a schematic structural diagram of an electrode assembly provided in some other embodiments of the present application.
  • Figure 7 is a cross-sectional view of an electrode assembly provided by some embodiments of the present application.
  • Figure 8 is a schematic structural view of the positive electrode porous current collector shown in Figure 7;
  • Fig. 9 is a schematic structural view of the negative electrode porous current collector shown in Fig. 7;
  • Fig. 10 is a schematic structural view of a wound electrode assembly provided by some embodiments of the present application.
  • Fig. 11 is a schematic structural diagram of a laminated electrode assembly provided by some embodiments of the present application.
  • Icons 1-electrode assembly; 11-positive electrode; 111-positive plate; 1111-positive porous current collector; 1111a-first part; 1111b-second part; 1112-positive active material layer; 12-negative electrode; 121-negative plate; 1213b-through hole; 13-isolation film; 2-accommodating part; 21-housing; 22-end cover; 23-electrode terminal; 10-electrochemical device; 100-battery; 200-controller; 300-motor; 1000-vehicle; Z-thickness direction; Y-first direction.
  • connection should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediary, or an internal connection between two components.
  • connection should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediary, or an internal connection between two components.
  • “Plurality” in this application refers to two or more (including two).
  • electrochemical devices are more and more widely used, and at the same time, higher requirements are placed on the energy density of electrochemical devices.
  • the active material of the positive pole plate adopts a high-nickel ternary material
  • the active material of the negative pole plate adopts a silicon material
  • the safety of the high-nickel ternary material and the expansion and pulverization of silicon and low first effect are always unresolved problems in the industry. Therefore, the effect of using this scheme to increase the energy density of the electrochemical device is not very satisfactory.
  • the energy density of the electrochemical device can also be increased by increasing the active material loading per unit area of the current collector, that is, increasing the thickness of the active material layer of the pole piece.
  • the thickness of the active material layer increases to a certain value, there are problems such as cracking of the pole piece and powder dropping, and the effect of increasing the energy density of the electrochemical device is not ideal.
  • the inventor has designed an electrode assembly after in-depth research, the positive electrode is set as a multi-layer positive electrode sheet, the multi-layer positive electrode sheet is continuously arranged along the thickness direction of the electrode assembly, and the positive electrode sheet uses a positive electrode porous current collector;
  • the multi-layer positive electrode sheet is continuously arranged to form a thick electrode, which increases the thickness of the positive electrode, reduces the amount of the separator, reduces the cost of the separator, and effectively improves the energy density of the electrochemical device.
  • the positive electrode is a thick electrode formed by continuous arrangement of multiple positive electrode sheets, the positive electrode active material layer in each layer of positive electrode sheet is relatively thin, and it is not easy to crack, powder drop, etc.
  • the multilayer negative electrode sheets are continuously arranged to form a thick electrode, which increases the thickness of the negative electrode, reduces the amount of separator, reduces the cost of the separator, and effectively improves the energy density of the electrochemical device.
  • the negative electrode is a thick electrode formed by continuous arrangement of multi-layer negative electrode sheets, the negative electrode active material layer in each layer of negative electrode sheets is relatively thin, so it is not easy to crack and drop powder.
  • the electrode assembly provided in the embodiments of the present application is suitable for electrochemical devices and electrical equipment using electrochemical devices.
  • An embodiment of the present application provides an electric device, where the electric device includes an electrochemical device, and the electrochemical device is used to provide electric energy.
  • Electrical equipment may include, but is not limited to: vehicles, mobile phones, laptops, headphones, video recorders, calculators, ships, spacecraft, electric toys, etc.
  • Vehicles can be fuel vehicles, gas vehicles, new energy vehicles, motorcycles, power-assisted bicycles, etc.
  • Spacecraft can be airplanes, rockets, space shuttles, spaceships, etc.
  • electric toys can be game consoles, electric car toys, electric boat toys, and electric airplane toys; electric tools can be metal cutting electric tools, grinding electric tools, assembly electric tools, railway electric tools, etc.
  • the embodiment of the present application does not impose special limitations on the above electric equipment.
  • FIG. 1 is a schematic structural diagram of a vehicle 1000 provided by some embodiments of the present application.
  • the interior of the vehicle 1000 is provided with a battery 100 , the battery 100 can be used for power supply of the vehicle 1000 , and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000 .
  • the vehicle 1000 may further include a controller 200 and a motor 300 , the controller 200 is used to control the battery 100 to supply power to the motor 300 .
  • the battery 100 may serve as an operating power source of the vehicle 1000 . For example, it is used for starting, navigating, and running power requirements of the vehicle 1000 .
  • the battery 100 can also be used as a driving power source of the vehicle 1000 to provide driving power for the vehicle 1000 instead of or partially replacing fuel oil or natural gas.
  • the battery 100 may include one or more electrochemical devices 10 .
  • the battery 100 may include one or more electrochemical devices 10 .
  • the multiple electrochemical devices 10 can be connected in series, parallel or mixed.
  • the mixed connection means that the multiple electrochemical devices 10 are both connected in series and in parallel.
  • the battery 100 may also include a confluence part, through which the multiple electrochemical devices 10 can be electrically connected, so as to realize the series, parallel or mixed connection of the multiple electrochemical devices 10 .
  • Bus parts can be metallic conductors, such as,
  • FIG. 2 is a schematic structural diagram of an electrochemical device 10 provided in an embodiment of the present application.
  • the electrochemical device 10 includes an electrode assembly 1 , and the electrochemical device 10 generates electrical energy through a chemical reaction between the electrode assembly 1 and the electrolyte.
  • the electrochemical device 10 may be a lithium-ion battery, a lithium-sulfur battery, a sodium-lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, which is not limited in this embodiment of the present application.
  • the electrochemical device 10 may be in the form of a cylinder, a flat body, a cuboid or other shapes, which are not limited in this embodiment of the present application.
  • Electrochemical devices 10 are generally classified into three types according to packaging methods: cylindrical batteries, square batteries and pouch batteries, which are not limited in this embodiment of the present application.
  • the electrochemical device 10 may further include a housing 2 for housing the electrode assembly 1 , and the housing 2 may be a housing, such as an aluminum shell or a steel shell.
  • the receiving part 2 can also be a storage bag, for example, a storage bag made of aluminum-plastic film.
  • the container 2 may include a housing 21 and an end cap 22 .
  • the casing 21 is a component for accommodating the electrode assembly 1 , and the casing 21 may be a hollow structure with an opening formed at one end.
  • the housing 21 can be in various shapes, such as cylinder, cuboid and so on.
  • the housing 21 can be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, and the like.
  • the end cap 22 is a component that covers the opening of the housing 21 to isolate the internal environment of the electrochemical device 10 from the external environment.
  • the end cap 22 covers the opening of the casing 21 , and the end cap 22 and the casing 21 jointly define a sealed space for accommodating the electrode assembly 1 , electrolyte and other components.
  • the shape of the end cap 22 can be adapted to the shape of the housing 21.
  • the housing 21 is a cuboid structure, and the end cap 22 is a rectangular plate-shaped structure adapted to the housing 21.
  • the housing 21 is a cylindrical structure, and the end cap 22 is a circular plate-shaped structure adapted to the housing 21.
  • the material of the end cap 22 can also be various, for example, copper, iron, aluminum, steel, aluminum alloy and so on.
  • electrode terminals 23 may be provided on the end cap 22 , and the electrode terminals 23 are used to electrically connect with the electrode assembly 1 to output electric energy of the electrochemical device 10 .
  • FIG. 3 is a schematic structural view of the electrode assembly 1 provided in some embodiments of the present application.
  • FIG. 4 is a schematic structural view of the positive electrode sheet 111 shown in FIG. 3
  • FIG. 5 is a schematic structural view of the negative electrode sheet 121 shown in FIG. 4 .
  • the embodiment of the present application provides an electrode assembly 1 .
  • the electrode assembly 1 includes a positive electrode 11 , a negative electrode 12 and a separator 13 .
  • the separator 13 is arranged between the positive electrode 11 and the negative electrode 12 to isolate the positive electrode 11 and the negative electrode 12 .
  • the positive electrode 11 includes a multilayer positive electrode sheet 111 continuously arranged along the thickness direction Z of the electrode assembly 1, the positive electrode sheet 111 includes a positive electrode porous current collector 1111 and a positive electrode active material layer 1112, and the positive electrode active material layer 1112 is arranged on the surface of the positive electrode porous current collector 1111;
  • the pole active material layer 1212 and the negative pole active material layer 1212 are disposed on the surface of the negative pole porous current collector 1211 .
  • the electrode assembly 1 there may be one positive electrode 11 and a plurality of negative electrodes 12 .
  • both the positive electrode 11 and the negative electrode 12 are one, and the positive electrode 11 and the negative electrode 12 are separated by a separator 13 .
  • there are multiple positive electrodes 11 and negative electrodes 12 and adjacent positive electrodes 11 and negative electrodes 12 are separated by a separator 13 .
  • the electrode assembly 1 can be a wound structure or a laminated structure. If the electrode assembly 1 has a wound structure, there can be one positive electrode 11 and a plurality of negative electrodes 12 . If the electrode assembly 1 has a laminated structure, there can be one positive electrode 11 and a plurality of negative electrodes 12 .
  • the multilayer positive electrode sheets 111 are arranged continuously along the thickness direction Z of the electrode assembly 1 , that is, there is no separator between every two adjacent layers of positive electrode sheets 111 .
  • the multilayer negative electrode sheets 121 are arranged continuously along the thickness direction Z of the electrode assembly 1 , that is, there is no separator between every two adjacent layers of negative electrode sheets 121 .
  • the positive electrode 11 includes multilayer positive electrode sheets 111 arranged continuously along the thickness direction Z of the electrode assembly 1
  • the negative electrode 12 may also include multilayer negative electrode sheets 121 continuously arranged along the thickness direction Z of the electrode assembly 1. If there is only one layer of negative electrode sheet 121 in the negative electrode 12, the current collector in the negative electrode sheet 121 may or may not be provided with holes.
  • the negative electrode 12 includes multilayer negative electrode sheets 121 continuously arranged along the thickness direction Z of the electrode assembly 1
  • the positive electrode 11 may also include multilayer negative electrode sheets 121 continuously arranged along the thickness direction Z of the electrode assembly 1. If there is only one layer of positive electrode sheet 111 in the positive electrode 11, the current collector in the positive electrode sheet 111 may or may not be provided with holes.
  • the number of layers of the positive electrode sheet 111 in the positive electrode 11 and the number of layers of the negative electrode sheet 121 in the negative electrode 12 may be equal or different.
  • the number of layers of the positive electrode sheet 111 in the positive electrode 11 is less than the number of layers of the negative electrode sheet 121 in the negative electrode 12, and for another example, the number of layers of the positive electrode sheet 111 in the positive electrode 11 is greater than the number of layers of the negative electrode sheet 121 in the negative electrode 12.
  • the number of layers of the positive electrode sheet 111 in the positive electrode 11 is equal to the number of layers of the negative electrode sheet 121 in the negative electrode 12 .
  • the positive electrode porous current collector 1111 can be a metal conductor, and the positive electrode porous current collector 1111 has a porous structure, which can be a porous structure formed by the material itself having pores, or a porous structure formed by processing.
  • the positive electrode active material layer 1112 is disposed on the surface of the positive electrode porous current collector 1111 , which is the surface of the positive electrode porous current collector 1111 in the thickness direction Z.
  • the active material in the positive electrode active material layer 1112 may be lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganate, and the like.
  • the negative electrode porous current collector 1211 can be a metal conductor, and the negative electrode porous current collector 1211 has a porous structure, which can be a porous structure formed by the material itself having pores, or a porous structure formed by processing.
  • the negative electrode active material layer 1212 is disposed on the surface of the negative electrode porous current collector 1211 , which is the surface of the negative electrode porous current collector 1211 in the thickness direction Z.
  • the active material in the negative electrode active material layer 1212 may be carbon, silicon, silicon-carbon composite, and the like.
  • Separator 13 is a member that separates positive electrode 11 and negative electrode 12 .
  • the isolation film 13 can be made of various materials, such as PP (polypropylene, polypropylene) and PE (polyethylene, polyethylene).
  • the positive electrode 11 by setting the positive electrode 11 as a multilayer positive electrode sheet 111, and the multilayer positive electrode sheet 111 is continuously arranged to form a thick electrode, the thickness of the positive electrode 11 is increased, the amount of the separator 13 is reduced, the cost of the separator 13 is reduced, and the energy density of the electrochemical device 10 is effectively improved.
  • the positive electrode 11 is a thick electrode formed by continuous arrangement of multi-layer positive electrode sheets 111, the positive electrode active material layer 1112 in each layer of positive electrode sheets 111 is relatively thin, which is not prone to cracking, powder falling, etc., and the positive electrode sheets 111 can be stacked arbitrarily according to requirements.
  • the positive electrode sheet 111 adopts a porous current collector, which ensures the transmission of the electrolyte between the multilayer positive electrode sheets 111, improves the wetting effect of the electrolyte in the positive electrode 11, and ensures the transmission of ions (such as lithium ions) between the positive electrode 11 and the negative electrode 12.
  • the small gap between every two adjacent layers of positive electrode sheets 111 in the positive electrode 11 can accommodate the electrolyte, which increases the liquid retention capacity of the entire positive electrode 11 .
  • the negative electrode 12 is a thick electrode formed by continuous arrangement of multi-layer negative electrode sheets 121, the negative electrode active material layer 1212 in each layer of negative electrode sheets 121 is relatively thin, which is not prone to cracking, powder falling, etc., and the negative electrode sheets 121 can be stacked arbitrarily according to requirements.
  • the negative electrode sheet 121 adopts a porous current collector, which ensures the transmission of the electrolyte between the multilayer negative electrode sheets 121, improves the wetting effect of the electrolyte in the negative electrode 12, and ensures the transmission of ions (such as lithium ions) between the negative electrode 12 and the negative electrode 12.
  • the small gap between every two adjacent layers of negative electrode sheets 121 in the negative electrode 12 can accommodate the electrolyte, which increases the liquid retention capacity of the entire positive electrode 11 .
  • the ratio of the active material capacity per unit area of the negative electrode 12 to the active material capacity per unit area of the positive electrode 11 is 1.05-1.3.
  • the ratio of the active material capacity per unit area of the negative electrode 12 to the active material capacity per unit area of the positive electrode 11 is the CB (Cell Balance, battery balance) value.
  • the active material capacity per unit area of the negative electrode 12 is the ratio of the total amount of active materials in the negative electrode active material layer 1212 in the negative electrode 12 to the total area of the surface of the current collector that the negative electrode active material layer 1212 in the negative electrode 12 occupies.
  • the active material capacity per unit area of the positive electrode 11 is the ratio of the total amount of active material in the positive electrode active material layer 1112 in the positive electrode 11 to the total area of the surface of the current collector occupied by the positive electrode active material layer 1112 in the positive electrode 11.
  • the current collector referred to here is the negative electrode porous current collector 1211.
  • the ratio of the active material capacity per unit area of the negative electrode 12 to the active material capacity per unit area of the positive electrode 11 is set at 1.05-1.3, the occurrence of lithium precipitation can be effectively reduced and the service life of the electrochemical device 10 can be improved.
  • the capacity of the active material per unit area of the negative electrode 12 can be tested in the following manner.
  • the negative electrode 12 can be obtained by dismantling the lithium-ion secondary battery after it is completely discharged.
  • the negative electrode 12 has a thickness of h, and a part of 1 cm*1 cm*h is cut on the negative electrode 12 to obtain a negative electrode 12 per unit area. Cut out the negative electrode 12 of unit area and carry out following test:
  • the negative electrode 12 per unit area and the lithium metal sheet per unit area are used to form a button half-cell, which is fully charged at a rate not greater than 0.1C to obtain a charging capacity, which is the active material capacity per unit area of the negative electrode 12 .
  • the active material capacity per unit area of the positive electrode 11 can be tested in the following manner.
  • the positive electrode 11 can be obtained by dismantling the lithium-ion secondary battery after it is fully discharged.
  • the thickness of the positive electrode 11 is h 2 , and a part of 1 cm*1 cm*h 2 is cut on the negative electrode 12 to obtain a negative electrode 12 per unit area. Cut out the positive electrode 11 of unit area and carry out following test:
  • the positive electrode 11 per unit area and the lithium metal sheet per unit area are used to form a button-type half-cell, which is fully charged at a rate of not more than 0.1C to obtain a charging capacity.
  • the charging capacity is the active material capacity per unit area of the positive electrode 11 .
  • cutting positions of the positive electrode 11 and the negative electrode 12 are not specifically limited.
  • FIG. 6 is a schematic structural diagram of an electrode assembly 1 provided in some other embodiments of the present application.
  • the number of layers of the positive electrode sheet 111 in the positive electrode 11 is smaller than the number of layers of the negative electrode sheet 121 in the negative electrode 12 .
  • the negative electrode 12 includes a multi-layer negative electrode sheet 121 , and the positive electrode sheet 111 in the positive electrode 11 may be one layer or multiple layers.
  • the thickness of the positive electrode sheet 111 is equal to the thickness of the negative electrode sheet 121
  • the positive electrode sheet 111 in the positive electrode 11 has two layers
  • the negative electrode sheet 121 in the negative electrode 12 has three layers.
  • the thickness of the positive electrode sheet 111 and the thickness of the negative electrode sheet 121 can be equal by the thickness of the positive electrode porous current collector 1111 of the positive electrode sheet 111 being equal to the thickness of the negative electrode porous current collector 1211 of the negative electrode sheet 121, and the thickness of the positive electrode active material layer 1112 of the positive electrode sheet 111 being equal to the thickness of the negative electrode active material layer 1212 of the negative electrode sheet 121. It is understandable that due to limitations of production process and measurement technology, it is difficult to find two completely equal objects in practice. In this application, if the difference between two objects is within 20%, it can be considered that the two objects are equal.
  • the number of layers of the positive electrode sheet 111 in the positive electrode 11 is smaller than the number of layers of the negative electrode sheet 121 in the negative electrode 12, it is beneficial to increase the space for the negative electrode 12 to insert ions (such as lithium ions), so that more ions detached from the positive electrode sheet 111 can be embedded in the negative electrode sheet 121 during charging, which can effectively reduce the occurrence of lithium precipitation.
  • ions such as lithium ions
  • the sum of the thicknesses of the positive sheets 111 in the positive electrode 11 is smaller than the sum of the thicknesses of the negative sheets 121 in the negative electrode 12 .
  • a 0.1 ⁇ m high-precision digital display micrometer (Mitutoyo brand) can be used to measure the thickness of the pole piece.
  • Disassemble the assembled electrochemical device 10 take out the electrode pole piece and wash off the surface residue with diethyl carbonate (DEC) solvent; wipe the micrometer test head with a dust-free paper to remove foreign matter to ensure the test accuracy; put the pole piece into the micrometer test head, rotate the handle of the micrometer to closely contact the pole piece, and read the thickness value. Select ten different points on the pole piece, measure the ten thickness data and take the average value.
  • DEC diethyl carbonate
  • the sum of the thicknesses of the positive electrode sheets 111 in the positive electrode 11 is less than the sum of the thicknesses of the negative electrode sheets 121 in the negative electrode 12, and the number of layers of the positive electrode sheets 111 in the positive electrode 11 is set to be smaller than the number of layers of the negative electrode sheets 121 in the negative electrode 12.
  • the thickness of the positive electrode sheet 111 is equal to the thickness of the negative electrode sheet 121
  • the positive electrode sheet 111 in the positive electrode 11 has two layers
  • the negative electrode sheet 121 in the negative electrode 12 has three layers.
  • the sum of the thicknesses of the positive electrode sheets 111 in the positive electrode 11 is smaller than the sum of the thicknesses of the negative electrode sheets 121 in the negative electrode 12, it is beneficial to increase the space for the negative electrode 12 to insert ions (such as lithium ions), so that more ions detached from the positive electrode sheet 111 can be embedded in the negative electrode sheet 121 during charging, which can effectively reduce the occurrence of lithium precipitation.
  • ions such as lithium ions
  • FIG. 7 provides a cross-sectional view of an electrode assembly 1 in some embodiments of the present application.
  • the positive electrode porous current collector 1111 is provided with a plurality of through holes 1213a, the positive electrode porous current collector 1111 includes a first part 1111a and a second part 1111b arranged along the first direction Y, the positive electrode active material layer 1112 is arranged on the surface of the first part 1111a, and the second part 1111b of at least two positive electrode sheets 111 in the positive electrode 11 is connected.
  • the first direction Y is perpendicular to the thickness direction Z of the electrode assembly 1 .
  • the second portions 1111b of every two adjacent layers of positive electrode sheets 111 in the positive electrode 11 are connected, that is, the second portions 1111b of any two adjacent layers of positive electrode sheets 111 are all connected.
  • the positive electrode 11 including a first positive electrode sheet, a second positive electrode sheet and a third positive electrode sheet continuously arranged along the thickness direction Z of the electrode assembly 1 as an example
  • the second parts 1111b of every two adjacent layers of positive electrode sheets 111 in the positive electrode 11 are connected, which means that the second part 1111b of the first positive electrode sheet is connected with the second part 1111b of the second positive electrode sheet, and the second part 1111b of the second positive electrode sheet is connected with the second part 1111b of the third positive electrode sheet.
  • the first part 1111a is the part of the positive electrode porous current collector 1111 coated with the positive electrode active material layer 1112
  • the second part 1111b is the part of the positive electrode porous current collector 1111 not coated with the positive electrode active material layer 1112 .
  • the positive electrode porous current collector 1111 only the first part 1111a may have a porous structure, or both the first part 1111a and the second part 1111b may have a porous structure.
  • one end of the first part 1111a may be provided with the second part 1111b, or both ends of the first part 1111a may be provided with the second part 1111b.
  • the corresponding two layers of positive electrode porous current collectors 1111 can be connected in parallel.
  • both ends of the first part 1111a are provided with the second part 1111b.
  • the second portions 1111 b of every two adjacent layers of the positive electrode sheet 111 are connected, so that the multiple layers of the second portions 1111 b together form a positive tab.
  • Each adjacent two layers of positive electrode sheets 111 can be connected in various ways, such as welding, bonding with conductive adhesive, and the like.
  • the positive tab is used for electrical connection with the positive electrode terminal.
  • the second part 1111b of the positive electrode sheet 111 on both sides is connected to the second part 1111b of the positive electrode sheet 111 in the middle.
  • the second parts 1111b of at least two layers of positive electrode sheets 111 in the positive electrode 11 are connected, and the positive electrode porous current collectors 1111 of at least two layers of positive electrode sheets 111 are connected in parallel, so that the electron transmission path is greatly shortened, the overall impedance of the electrochemical device 10 is reduced, thereby reducing the temperature rise of charging and discharging, and improving the safety of the electrochemical device 10.
  • the negative electrode porous current collector 1211 is provided with a plurality of through holes 1213b, the negative electrode porous current collector 1211 includes a third part 1211a and a fourth part 1211b arranged along the first direction Y, the negative electrode active material layer 1212 is arranged on the surface of the third part 1211a, and the fourth part 1211b of at least two negative electrode sheets 121 in the negative electrode 12 is connected.
  • the fourth portions 1211b of every two adjacent layers of negative electrode sheets 121 in the negative electrode 12 are connected, that is, the fourth portions 1211b of any two adjacent layers of negative electrode sheets 121 are all connected.
  • the negative electrode 12 including the first negative electrode sheet, the second negative electrode sheet and the third negative electrode sheet continuously arranged along the thickness direction Z of the electrode assembly 1 as an example, the fourth parts 1211b of every two adjacent layers of negative electrode sheets 121 in the negative electrode 12 are connected, which means that the fourth part 1211b of the first negative electrode sheet is connected with the fourth part 1211b of the second negative electrode sheet, and the fourth part 1211b of the second negative electrode sheet is connected with the fourth part 1211b of the first negative and positive electrode sheets.
  • the third part 1211a is the part of the negative electrode porous current collector 1211 coated with the negative electrode active material layer 1212
  • the fourth part 1211b is the part of the negative electrode porous current collector 1211 not coated with the negative electrode active material layer 1212 .
  • the third part 1211a may have a porous structure, or both the third part 1211a and the fourth part 1211b may have a porous structure.
  • one end of the third portion 1211a may be provided with the fourth portion 1211b, or both ends of the third portion 1211a may be provided with the fourth portion 1211b.
  • the fourth part 1211b at one end of the two layers of the third part 1211a is connected, the corresponding two layers of negative electrode porous current collectors 1211 can be connected in parallel.
  • both ends of the third portion 1211a are provided with the fourth portion 1211b.
  • the fourth parts 1211b of every two adjacent layers of negative electrode sheets 121 are connected, so that the fourth parts 1211b of multiple layers jointly form a negative electrode tab.
  • Each adjacent two layers of negative electrode sheets 121 can be connected in various ways, such as welding, bonding with conductive adhesive, and the like.
  • the negative tab is used for electrical connection with the negative electrode terminal.
  • the fourth part 1211b of the negative electrode sheet 121 on both sides is connected to the fourth part 1211b of the negative electrode sheet 121 in the middle.
  • the fourth part 1211b of at least two layers of negative electrode sheets 121 in the negative electrode 12 is connected, and the negative electrode porous current collectors 1211 of at least two layers of negative electrode sheets 121 are connected in parallel, so that the electron transmission path is greatly shortened, the overall impedance of the electrochemical device 10 is reduced, thereby reducing the temperature rise of charging and discharging, and improving the safety of the electrochemical device 10.
  • FIG. 8 is a schematic structural diagram of the positive porous current collector 1111 shown in FIG. 7 , and a plurality of through holes 1213a on the positive porous current collector 1111 are disposed in the first portion 1111a.
  • the first part 1111a is a porous structure provided with a plurality of through holes 1213a, and the electrolyte can be transferred from one side of the first part 1111a in the thickness direction Z (not shown in FIG. 8 ) to the other side through the through holes 1213a.
  • the through hole 1213a on the first part 1111a may have various shapes, for example, a circle, a polygon, and the like. Exemplarily, in FIG. 8, a plurality of through holes 1213a are distributed in a rectangular array in the first part 1111a.
  • the second part 1111b is not provided with a through hole 1213a, and the electrolyte cannot pass through the second part 1111b to transfer from one side of the second part 1111b in the thickness direction Z to the other side.
  • a plurality of through holes 1213a on the positive electrode porous current collector 1111 are provided in the first part 1111a, that is, the second part 1111b is not provided with a through hole 1213a structure, so as to improve the flow capacity of the second part 1111b, ensure the strength of the second part 1111b, and improve the firmness after the connection of the two layers of the second part 1111b.
  • FIG. 9 is a schematic structural diagram of the negative electrode porous current collector 1211 shown in FIG. 7 , and the plurality of through holes 1213b on the negative electrode porous current collector 121 are disposed in the third portion 1211a.
  • the third part 1211a is a porous structure provided with a plurality of through holes 1213b through which the electrolyte can be transported from one side of the third part 1211a in the thickness direction Z (not shown in FIG. 9 ) to the other side.
  • the through hole 1213b on the third part 1211a may have various shapes, such as a circle, a polygon, and the like. Exemplarily, in FIG. 8 , a plurality of through holes 1213b are distributed in a rectangular array in the third portion 1211a.
  • the fourth part 1211b is not provided with a through hole 1213b, and the electrolyte cannot pass through the fourth part 1211b to be transferred from one side of the fourth part 1211b in the thickness direction Z to the other side.
  • the plurality of through holes 1213b on the negative electrode porous current collector 121 are arranged in the third part 1211a, that is, the fourth part 1211b is not provided with through holes 1213b, so as to improve the flow capacity of the fourth part 1211b, ensure the strength of the fourth part 1211b, and improve the firmness after the connection of the two layers of the fourth part 1211b.
  • the second portions 1111b of at least two layers of positive electrode sheets 111 in the positive electrode 11 are welded; and/or, the fourth portions 1211b of at least two layers of negative electrode sheets 121 in the negative electrode 12 are welded.
  • every two adjacent layers of second parts 1111b in the positive electrode 11 are welded, that is, all the second parts 1111b of the positive electrode 11 are welded together; and/or, every two adjacent layers of fourth parts 1211b in the negative electrode 12 are welded together.
  • two adjacent layers of the second part 1111b can be welded together in various ways, for example, penetration welding, seam welding and the like. Taking the positive electrode sheet 111 in the positive electrode 11 as an example with three layers, after the three layers of second parts 1111b are stacked together, the three layers of second parts 1111b are welded together by penetration welding, so as to realize the welding of every two adjacent layers of second parts 1111b.
  • two adjacent layers of the fourth part 1211b can be welded together in various ways, for example, penetration welding, seam welding and the like. Taking the negative electrode sheet 121 in the negative electrode 12 as an example with three layers, after the three layers of fourth parts 1211b are stacked together, the three layers of fourth parts 1211b are welded together by penetration welding, so as to realize the welding of every two adjacent layers of fourth parts 1211b.
  • the fourth part 1211b on the porous current collector 121 of the negative electrode are arranged in the third part 1211a, since the fourth part 1211b is not provided with through holes 1213b, it is convenient to weld all the fourth parts 1211b in the negative electrode 12 together by penetration welding to ensure the firmness after welding.
  • the second parts 1111b of at least two layers of positive electrode sheets 111 in the positive electrode 11 are welded, and the connection method is simple and efficient, ensuring the firmness of the connection of at least two layers of the second parts 1111b.
  • welding the fourth parts 1211b of at least two layers of negative electrode sheets 121 in the negative electrode 12 is simple and efficient, and ensures the firmness of the connection of at least two layers of fourth parts 1211b.
  • the porosity of the positive electrode porous current collector 1111 is 3%-40%; and/or, the porosity of the negative electrode porous current collector 1211 is 3%-40%.
  • the porosity of the positive porous current collector 1111 refers to the percentage of the total volume of all through holes 1213 a on the positive porous current collector 1111 to the total volume of the positive porous current collector 1111 .
  • the porosity of the negative electrode porous current collector 1211 refers to the percentage of the total volume of all through holes 1213 b on the negative electrode porous current collector 1211 to the total volume of the negative electrode porous current collector 1211 .
  • the porosity of the positive electrode porous current collector 1111 is set to 3%-40%, so that the electrolyte can maintain good transmission between the multilayer positive electrode sheets 111, and at the same time ensure that the positive electrode porous current collector 1111 has sufficient strength.
  • the porosity of the negative electrode porous current collector 1211 is set to 3%-40%, so that the electrolyte can maintain good transmission between the multilayer negative electrode sheets 121, reduce lithium deposition, and ensure that the negative electrode porous current collector 1211 has sufficient strength.
  • the porosity can be tested through the following steps: intercept 10 pole piece samples, the size of which is 50 mm ⁇ 100 mm, place them in a true porosity tester (model is AccuPyc II 1340), test the porosity of the samples, test the real volume Vol of the samples, and then use a multimeter thickness gauge to test the thickness T of 10 samples.
  • the apparent volume Vol 0 50 ⁇ 100 ⁇ T of the samples is calculated. Vol 0 -Vol)/Vol 0 x 100%. It should be understood that this is only exemplary, and other suitable methods can also be used to test porosity.
  • the positive electrode porous current collector 1111 includes at least one of metal foam or metal foil with through holes 1213a, and/or, the negative electrode porous current collector 1211 includes at least one of metal foam or metal foil with through holes 1213b.
  • the positive electrode porous current collector 1111 may be nickel foam, copper foam, aluminum foam, or the like. If the positive electrode porous current collector 1111 is metal aluminum foil with through holes 1213a opened, the positive electrode porous current collector 1111 may be nickel foil, copper foil, aluminum foil, etc. with through holes 1213a opened.
  • the negative electrode porous current collector 1211 may be nickel foam, copper foam, aluminum foam, or the like. If the negative electrode porous current collector 1211 is metal aluminum foil with through holes 1213b opened, the negative electrode porous current collector 1211 may be nickel foil, copper foil, aluminum foil, etc. with through holes 1213b opened.
  • the positive electrode porous current collector 1111 may be a metal foil, and the first part 1111a is made of a porous structure by processing the through holes 1213a on the metal foil.
  • the negative electrode porous current collector 1211 can be a metal foil, and the third part 1211a has a porous structure by processing the through holes 1213b on the metal foil.
  • both the positive electrode porous current collector 1111 and the negative electrode porous current collector 1211 can be metal foam, and the metal foam is a metal material containing foam holes, which has good permeability, ensures the efficient transmission of the electrolyte between the multilayer positive electrode sheets 111, and has the advantages of low density and good heat insulation performance.
  • Both the positive electrode porous current collector 1111 and the negative electrode porous current collector 1211 can also be metal foils with through holes, which have the advantages of simple structure and low production cost.
  • FIG. 10 is a schematic structural diagram of a wound electrode assembly provided in some embodiments of the present application, and the electrode assembly 1 may be of a wound structure.
  • the wound electrode assembly there may be one positive electrode 11 and a plurality of negative electrodes 12 .
  • the positive electrode 11 and the negative electrode 12 are both one, which can be stacked sequentially in the order of positive electrode 11-separator 13-negative electrode 12-separator 13, and then the stacked whole is wound to form a wound electrode assembly.
  • FIG. 11 is a schematic structural diagram of a laminated electrode assembly provided in some embodiments of the present application.
  • the electrode assembly 1 may be a laminated structure.
  • the laminated electrode assembly there may be one positive electrode 11 and negative electrodes 12, or there may be multiple ones.
  • the electrode assembly 1 includes a multilayer positive electrode 11 , a multilayer separator 13 and a multilayer negative electrode 12 , and the multilayer positive electrode 11 , the multilayer separator 13 and the multilayer negative electrode 12 are laminated to form a laminated structure.
  • three positive electrodes 11 and three negative electrodes 12 can be stacked sequentially in the order of positive electrode 11-separator 13-negative electrode 12-separator 13-positive electrode 11-separator 13-negative electrode 12-separator 13-positive electrode 11-separator 13-negative electrode 12 to form a laminated electrode assembly.
  • the multilayer positive electrode 11 , the multilayer separator 13 and the multilayer negative electrode 12 are laminated to form a laminated structure.
  • the electrode assembly 1 with this structure has the advantages of simple molding, low production cost and high energy density.
  • the size (reference) of the electrochemical device 10 is 8.4*42*97mm 3 .
  • the number of layers of the positive electrode sheet 111 in the positive electrode 11 is 2 layers
  • the active material of the positive electrode sheet 111 is lithium iron phosphate
  • the coating surface density of the positive electrode sheet 111 is 13 mg/cm 2
  • the compacted density is 2.2 g/cm 3
  • an aluminum current collector with a thickness of 13 ⁇ m is used.
  • the negative electrode sheet 121 in the negative electrode 12 has two layers, and the active material of the negative electrode sheet 121 is graphite.
  • the negative electrode sheet 121 has a coated surface density of 6.3 mg/cm 2 , a compacted density of 1.52 g/cm 3 , and a copper current collector with a thickness of 8 ⁇ m.
  • the isolation film 13 is made of PP (polypropylene, polypropylene), and the thickness of the isolation film 13 is 20 ⁇ m.
  • the energy density of the electrochemical device 10 using the wound electrode assembly and the laminated electrode assembly was measured.
  • Embodiment 2 The difference between Embodiment 2 and Embodiment 1 is that the number of layers of the positive electrode sheet 111 in the positive electrode 11 is 3 layers, and the number of layers of the negative electrode sheet 121 in the negative electrode 12 is also 3 layers.
  • Embodiment 3 The difference between Embodiment 3 and Embodiment 1 is that the number of layers of the positive electrode sheet 111 in the positive electrode 11 is 2 layers, and the number of layers of the negative electrode sheet 121 in the negative electrode 12 is also 1 layer.
  • Embodiment 4 The difference between Embodiment 4 and Embodiment 1 is that the number of layers of the positive electrode sheet 111 in the positive electrode 11 is one, and the number of layers of the negative electrode sheet 121 in the negative electrode 12 is also two layers.
  • Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the number of layers of the positive electrode sheet 111 in the positive electrode 11 is one layer, and the number of layers of the negative electrode sheet 121 in the negative electrode 12 is also one layer.
  • the electrochemical device 10 adopts a wound electrode assembly. Whether the positive electrode 11 includes a multi-layer positive electrode sheet 111 or the negative electrode 12 includes a multi-layer negative electrode sheet 121, the energy density of the electrochemical device 10 is higher than that of the electrochemical device 10 in which the positive electrode sheet 111 in the positive electrode 11 and the negative electrode sheet 121 in the negative electrode 12 are all one layer.
  • the electrochemical device 10 adopts a laminated electrode assembly 1, and whether the positive electrode 11 includes a multi-layer positive electrode sheet 111 or the negative electrode 12 includes a multi-layer negative electrode sheet 121, the energy density of the electrochemical device 10 is higher than that of the electrochemical device 10 in which the positive electrode sheet 111 in the positive electrode 11 and the negative electrode sheet 121 in the negative electrode 12 are all one layer.
  • the active material capacity per unit area of the positive electrode 11 is 3.64mAh/cm 3
  • the active material capacity per unit area of the negative electrode 12 is 3.82mAh/cm 3 .
  • the electrochemical device 10 was observed for lithium deposition after 1000 cycles.
  • Example 6 The difference between Example 6 and Example 5 is that the active material capacity per unit area of the negative electrode 12 is 4mAh/cm 3 .
  • Example 7 The difference between Example 7 and Example 5 is that the active material capacity per unit area of the negative electrode 12 is 4.37mAh/cm 3 .
  • Comparative Example 2 The difference between Comparative Example 2 and Example 5 is that the active material capacity per unit area of the negative electrode 12 is 3.64mAh/cm 3 .
  • the porosity of the positive electrode porous current collector 1111 of the positive electrode sheet 111 is 3%, and the material of the positive electrode porous current collector 1111 is aluminum. In an environment of 25° C., the DC internal resistance of the electrochemical device 10 is measured at 50% state of charge.
  • Embodiment 9 The difference between Embodiment 9 and Embodiment 8 is that the porosity of the positive electrode porous current collector 1111 of the positive electrode sheet 111 is 10%.
  • Example 10 The difference between Example 10 and Example 8 is that the porosity of the positive electrode porous current collector 1111 of the positive electrode sheet 111 is 20%.
  • Example 11 The difference between Example 11 and Example 8 is that the porosity of the positive electrode porous current collector 1111 of the positive electrode sheet 111 is 30%.
  • Comparative Example 3 The difference between Comparative Example 3 and Example 8 is that the porosity of the positive electrode porous current collector 1111 of the positive electrode sheet 111 is 2%.
  • the porosity of the negative electrode porous current collector 1211 of the negative electrode sheet 121 is 3%, and the material of the negative electrode porous current collector 1211 is copper. In an environment of 25° C., the state of charging and decomposing lithium of the 0.5C electrochemical device 10 was observed.
  • Example 13 The difference between Example 13 and Example 12 is that the porosity of the negative electrode porous current collector 1211 of the negative electrode sheet 121 is 10%.
  • Example 14 The difference between Example 14 and Example 12 is that the porosity of the negative electrode porous current collector 1211 of the negative electrode sheet 121 is 20%.
  • Example 15 The difference between Example 15 and Example 12 is that the porosity of the negative electrode porous current collector 1211 of the negative electrode sheet 121 is 30%.
  • Comparative Example 4 The difference between Comparative Example 4 and Example 12 is that the porosity of the negative electrode porous current collector 1211 of the negative electrode sheet 121 is 2%.

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Abstract

Les modes de réalisation de la présente demande se rapportent au domaine technique du stockage d'énergie. L'invention concerne un ensemble électrode, un appareil électrochimique et un dispositif électrique. L'ensemble électrode comprend une électrode positive, une électrode négative et un séparateur, le séparateur étant disposé entre l'électrode positive et l'électrode négative, de façon à séparer l'électrode positive de l'électrode négative. L'électrode positive comprend une pluralité de couches de plaques positives, qui sont disposées en continu dans la direction de l'épaisseur de l'ensemble électrode, et chaque plaque positive comprend un collecteur de courant poreux positif et une couche de matériau actif positif, revêtue sur une surface du collecteur de courant poreux positif ; et/ou l'électrode négative comprend une pluralité de couches de plaques négatives, qui sont disposées en continu dans la direction de l'épaisseur de l'ensemble électrode, et chaque plaque négative comprend un collecteur de courant poreux négatif et une couche de matériau actif négatif, revêtue sur une surface du collecteur de courant poreux négatif. Une électrode positive est configurée pour comprendre une pluralité de couches de plaques positives et/ou une électrode négative est configurée pour comprendre une pluralité de couches de plaques négatives, de telle sorte que l'épaisseur de l'électrode positive et/ou de l'électrode négative est augmentée, moins de séparateurs sont utilisés, et la densité d'énergie d'un appareil électrochimique est efficacement améliorée.
PCT/CN2022/073054 2022-01-20 2022-01-20 Ensemble électrode, appareil électrochimique et dispositif électrique WO2023137673A1 (fr)

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KR20140137660A (ko) * 2013-05-23 2014-12-03 주식회사 엘지화학 이차전지용 전극 및 이를 포함하는 이차전지
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CN106469825A (zh) * 2015-08-21 2017-03-01 北京好风光储能技术有限公司 一种高功率大容量锂离子电池及其制备方法
CN108346772A (zh) * 2017-01-22 2018-07-31 北京好风光储能技术有限公司 一种锂浆料电池及其非对称式电极片

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