WO2023035669A1 - 电极组件、电池单体、电池以及用电装置 - Google Patents

电极组件、电池单体、电池以及用电装置 Download PDF

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Publication number
WO2023035669A1
WO2023035669A1 PCT/CN2022/094258 CN2022094258W WO2023035669A1 WO 2023035669 A1 WO2023035669 A1 WO 2023035669A1 CN 2022094258 W CN2022094258 W CN 2022094258W WO 2023035669 A1 WO2023035669 A1 WO 2023035669A1
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Prior art keywords
bending
area
layer
isolation layer
electrode assembly
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PCT/CN2022/094258
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English (en)
French (fr)
Inventor
郭锁刚
付成华
叶永煌
常雯
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宁德时代新能源科技股份有限公司
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Application filed by 宁德时代新能源科技股份有限公司 filed Critical 宁德时代新能源科技股份有限公司
Priority to EP22866147.6A priority Critical patent/EP4383435A1/en
Priority to CN202280005439.6A priority patent/CN116114115A/zh
Priority to KR1020247007352A priority patent/KR20240039043A/ko
Publication of WO2023035669A1 publication Critical patent/WO2023035669A1/zh
Priority to US18/595,075 priority patent/US20240204265A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • 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
    • H01M10/04—Construction or manufacture in general
    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/0404—Machines for assembling batteries
    • H01M10/0409—Machines for assembling batteries for cells with wound electrodes
    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/0431—Cells with wound or folded electrodes
    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/0436—Small-sized flat cells or batteries for portable equipment
    • 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
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/463—Separators, membranes or diaphragms characterised by their shape
    • H01M50/466—U-shaped, bag-shaped or folded
    • 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
    • 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
    • H01M50/491—Porosity
    • 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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/457—Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
    • 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 field of battery technology, and more specifically, to an electrode assembly, a battery cell, a battery and an electrical device.
  • Battery cells are widely used in electronic equipment, such as mobile phones, laptop computers, battery cars, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools, etc.
  • the battery cells may include nickel-cadmium battery cells, nickel-hydrogen battery cells, lithium-ion battery cells, secondary alkaline zinc-manganese battery cells, and the like.
  • the present application provides an electrode assembly, a battery cell, a battery and an electric device, which can improve safety.
  • an embodiment of the present application provides an electrode assembly, including a positive pole piece, a negative pole piece, and a separator assembly, and the spacer component is used to isolate the positive pole piece and the negative pole piece.
  • the isolation component includes a base area and a reinforcement area connected to the base area, the thickness of the reinforcement area is greater than the thickness of the base area. At least part of the reinforcement zone is located between adjacent positive and negative electrode tabs.
  • the strengthening area can be used to correspond to the position where lithium is easily deposited on the negative electrode sheet. In this way, when the negative electrode sheet is releasing lithium, the strengthening area can effectively separate the positive electrode sheet and the negative electrode sheet, reducing lithium branching. The risk of crystal passing through the isolation components is reduced, improving life and safety.
  • the base region can have a smaller thickness, which can reduce the amount of isolation components, reduce costs, and increase the energy density of the electrode assembly.
  • the thickness of the reinforced region is 2 ⁇ m-100 ⁇ m.
  • the above-mentioned technical solution limits the thickness of the reinforced region to 2 ⁇ m-100 ⁇ m to balance the energy density and safety of the electrode assembly.
  • the positive electrode sheet, the separator assembly and the negative electrode sheet are wound to form a bending area, and at least part of the reinforcement area is disposed in the bending area.
  • the strengthening area is set in the bending area where lithium is easy to be deposited. Even if lithium precipitation occurs in the bending area, the strengthening area can block lithium dendrites and reduce the conduction between the positive electrode and the negative electrode. probability, effectively reducing the risk of short circuit and improving the service life and safety of the electrode assembly.
  • the positive electrode tab includes a first bent portion located in the bent region and adjacent to the reinforcement area
  • the negative electrode tab includes a second bent portion adjacent to the first bent portion.
  • the reinforcement zone includes a plurality of bent layers located in the bent area and stacked between the first bent portion and the second bent portion.
  • the multiple bending layers can block lithium dendrites when lithium is separated in the second bending part, reduce the risk of lithium dendrites contacting the first bending part, and improve safety.
  • At least the inner side of the first bent portion is provided with a reinforced area and a second bent portion.
  • the curvature of the second bending part located inside the first bending part is greater than that of the first bending part, so the second bending part is more prone to shedding of the active material during the bending process, that is to say, the first bending part
  • the second bent portion inside the bent portion is more prone to lithium precipitation.
  • the strengthening region of the above technical solution can separate the first bending part from the second bending part located inside the first bending part, even if the second bending part is decomposing lithium, it can also reduce lithium dendrites passing through the strengthening region probability, reduce the risk of short circuit and improve safety.
  • the first bending part includes a first collector part and a first active material layer disposed on the surface of the first collector part, and the thickness of the first active material layer is h1.
  • the second bending part includes a second current collecting part and a second active material layer disposed on the surface of the second current collecting part, the thickness of the second active material layer is h2, the thickness of the bending layer is h3, and the second current collecting part The thickness is h4.
  • the maximum distance between the first bent portion and the second bent portion is X.
  • the number of layers of the bending layer located between the first bending part and the second bending part is Y, and Y is a positive integer greater than 1.
  • the active material capacity per unit area of the first active material layer is A1
  • the active material capacity per unit area of the second active material layer is A2, and A2/A1 ⁇ 1.
  • h1, h2, h3, h4, X and Y satisfy:
  • the number of bending layers can be set according to the above formula to balance the safety and energy density of the electrode assembly.
  • the first bending part includes a first collector part and a first active material layer disposed on the surface of the first collector part, and the thickness of the first active material layer is h1.
  • the second bending part includes a second current collecting part and a second active material layer disposed on the surface of the second current collecting part, the thickness of the second active material layer is h2, the thickness of the bending layer is h3, and the second current collecting part The thickness is h4.
  • the maximum distance between the first bent portion and the second bent portion is X.
  • the number of layers of the bending layer located between the first bending part and the second bending part is Y, and Y is a positive integer greater than 1.
  • the active material capacity per unit area of the first active material layer is A1
  • the active material capacity per unit area of the second active material layer is A2, and A2/A1 ⁇ 1.
  • h1, h2, h3, h4, X and Y satisfy:
  • the number of bending layers can be set according to the above formula to balance the safety and energy density of the electrode assembly.
  • the value of h3 is 1 ⁇ m-20 ⁇ m to balance the safety and energy density of the electrode assembly.
  • the value of X is from 10 ⁇ m to 5000 ⁇ m.
  • the positive electrode sheet includes a plurality of positive electrode bending parts arranged along the winding direction, and at least the positive electrode bending part formed by the first bending of the positive electrode sheet is set as the first bending part.
  • the curvature of the positive bending portion formed by the first bending of the positive electrode sheet is relatively large, and the negative electrode sheet adjacent to the positive bending portion formed by the first bending of the positive electrode sheet is easier to charge when charging.
  • the positive electrode bending part formed by the first bending of the positive electrode sheet is set as the first bending part, so that the reinforced area can effectively bend the positive electrode formed by the first bending of the positive electrode sheet.
  • the folds are isolated from the lithium dendrites, reducing the risk of short circuits and improving safety.
  • the positive bent portion formed by the second bending of the positive electrode sheet is also set as the first bent portion.
  • the positive electrode bending part formed by the second bending of the positive electrode piece is set as the first bending part, so that the reinforced area can effectively bend the positive electrode formed by the second bending of the positive electrode piece.
  • the folds are isolated from the lithium dendrites, reducing the risk of short circuits and improving safety.
  • the total thickness of the reinforced area inside the positive bending part formed by the first bending of the positive electrode sheet is T1
  • the reinforcement area located at the positive bending part formed by the second bending of the positive electrode sheet The total thickness of the inner reinforced area is T2, T1 ⁇ T2.
  • the above technical solution makes T1 ⁇ T2, so as to reduce the risk of conduction between the positive electrode bending part formed by the first bending of the positive electrode sheet and the lithium dendrite, and improve the safety of the battery cell.
  • both sides of the first bending part are provided with a reinforcement area and a second bending part, and the total thickness of the reinforcement area located inside the first bending part is greater than or equal to that of the reinforcement area located outside the first bending part.
  • the total thickness of the reinforced region is used to reduce the risk of conduction between the first bending portion and the lithium dendrite, and improve the safety of the battery cell.
  • the positive electrode sheet includes a plurality of positive electrode bending parts arranged along the winding direction, at least the positive electrode bending part formed by the last bending of the positive electrode sheet is set as the first bending part, so as to lower the positive electrode
  • the risk of conduction between the positive electrode bending part formed by the last bending of the pole piece and the lithium dendrite improves the safety of the battery cell.
  • the positive pole piece, the separator assembly and the negative pole piece are wound to form a flat area, and the straight area is connected to the bent area. At least part of the base area is disposed in the flat area.
  • Both the positive pole piece and the negative pole piece located in the flat area are in a straight state, the active material in the flat area is not easy to fall off, and the negative pole piece located in the flat area is not prone to the problem of lithium precipitation. Therefore, even if the above technical solution will substrate Setting the area to a flat area can also improve the insulation between the positive and negative electrodes and reduce the risk of short circuit.
  • reinforcing regions and matrix regions there are multiple reinforcing regions and matrix regions, and the reinforcing regions and the matrix regions are arranged alternately along the winding direction.
  • the multiple reinforcement regions may respectively correspond to the multiple positive bending portions of the positive electrode sheet, so as to reduce the risk of short circuit in the multiple positive electrode bending portions of the positive electrode sheet and improve safety.
  • the thicknesses of the plurality of reinforced regions gradually decrease from the inside to the outside.
  • the above technical solution can increase the thickness of the reinforced area in the area with high short-circuit risk, and reduce the thickness of the reinforced area in the area with low short-circuit risk, which can improve safety and save the amount of isolation components.
  • the thickness difference between adjacent reinforcing regions is 0.5 ⁇ m-10 ⁇ m.
  • the reinforcing region is configured as a multi-layer structure, and the base region is configured as a single-layer structure.
  • the reinforced region with a multi-layer structure can more effectively block lithium dendrites, reduce the risk of short circuit, and improve safety.
  • the reinforced region with a multi-layer structure can adopt a smaller thickness, which can reduce the amount of isolation components and increase the energy density of the electrode assembly.
  • the isolation assembly includes a first isolation layer and a second isolation layer, the first isolation layer is used to insulate and isolate the positive electrode sheet and the negative electrode sheet, and at least part of the second isolation layer is located between the positive electrode sheet and the negative electrode sheet. Between the sheets and laminated with the first isolation layer. The area of the first isolation layer that overlaps the second isolation layer and the second isolation layer form a reinforcement area of the isolation assembly, and the area of the first isolation layer that does not overlap with the second isolation layer forms a base area.
  • a second isolation layer is additionally added to the electrode assembly to form a reinforced region with a larger thickness on the isolation assembly, thereby reducing the risk of short circuit caused by analytic lithium and improving safety.
  • the thickness of the second isolation layer is less than or equal to the thickness of the first isolation layer.
  • the first isolation layer and the second isolation layer can play the function of multi-layer protection, so the increased second isolation layer can have a thickness not greater than that of the first isolation layer, so as to reduce the thickness of the second isolation layer. Dosage.
  • At least part of the second isolation layer is separated from the first isolation layer in the lamination direction of the first isolation layer and the second isolation layer.
  • the part of the second isolation layer separated from the first isolation layer is less affected by the first isolation layer, and the second isolation layer is stretched to a lesser extent, The risk of defects is low.
  • the above technical solution can effectively reduce the risk of lithium dendrites passing through the first isolation layer and the second isolation layer, and improve safety.
  • the positive electrode piece, the separator assembly and the negative electrode piece are wound to form a bent area and a straight area, and the straight area is connected to the bent area.
  • a part of the second isolation layer is located in the bent area, and another part of the second isolation layer is located in the straight area.
  • the second isolation layer is separated from the first isolation layer.
  • the second isolation layer is attached to the first isolation layer.
  • the risk of lithium precipitation in the bending area is relatively high, and the second isolation layer in the bending area is separated from the first isolation layer, which can effectively reduce the penetration of lithium dendrites through the first isolation layer and the second isolation layer. layers of risk and improve security.
  • the second isolation layer is attached to the first isolation layer, which can reduce the movement range of the second isolation layer along the winding direction and reduce the risk of dislocation of the second isolation layer.
  • the second insulation layer is formed by folding the ends of the first insulation layer.
  • the second isolation layer is directly extended from the end of the first isolation layer, without adding and fixing the second isolation layer separately, so that the winding process is more convenient and the integrity of the electrode assembly is better .
  • the positive electrode sheet, the separator assembly and the negative electrode sheet are wound, the electrode assembly includes an initial segment along the winding direction, and the end of the first separator layer is located at the initial segment.
  • the second isolation layer can extend from the initial section along the winding direction and pass through the positive electrode bending part formed by the first bending of the positive electrode sheet, which can reduce the lithium dendrites and pass through the first isolation layer at the same time.
  • the positive electrode piece, the separator assembly, and the negative electrode piece are wound to form a bending area
  • the bending area includes a first bending portion close to the starting section along the winding direction
  • the first bending portion is provided with The first isolation layer and the second isolation layer, the second isolation layer extending from the end of the first isolation layer and beyond the first bending position.
  • the bending curvature of the positive pole piece and the negative pole piece is the largest, and the negative pole piece has the highest risk of lithium precipitation during charging.
  • the second isolation layer extends beyond the first bending position, and the first isolation layer and the second isolation layer can at least protect the first bending position where the problem of lithium precipitation is most likely to occur, while also saving the use of the second isolation layer, thereby While saving costs, improve the safety and service life of the electrode assembly.
  • the positive electrode sheet, the separator assembly and the negative electrode sheet are wound to form a bent area.
  • the bending area includes a plurality of bending positions arranged along the winding direction
  • the electrode assembly includes a plurality of second isolation layers
  • the first isolation layer and the plurality of second isolation layers are arranged in at least one of the plurality of bending positions.
  • the second isolation layer is provided at some or all of the multiple bending locations, which can effectively reduce the risk of short circuit at the bending locations and improve safety.
  • a plurality of second isolation layers are arranged at intervals along the winding direction.
  • the above technical solution can make the setting method of the second isolation layer more flexible, that is, the second isolation layer can be arbitrarily set to the position where the number of isolation layers needs to be increased, and at the same time, it can also reduce the The waste caused by increasing the second isolation layer improves the energy density.
  • the electrode assembly includes an initial segment along the winding direction.
  • the plurality of bending positions include a first bending position and a second bending position, and along the winding direction, the first bending position is closer to the starting section than the second bending position.
  • the thickness of the second isolation layer arranged at the first bending position is greater than the thickness of the second isolation layer arranged at the second bending position.
  • the above technical solution can strengthen the protection at the first bending part which is more likely to be short-circuited, improve safety, and save the amount of the second isolation layer.
  • the first isolation layer includes two surfaces along its thickness direction, and a plurality of second isolation layers are located on the same surface of the first isolation layer, so as to reduce the second isolation when the first isolation layer is tensioned.
  • the effect of the layer on the distance between the positive pole piece and the negative pole piece reduces the risk of lithium precipitation and improves safety.
  • multiple second isolation layers are bonded to the surface of the first isolation layer, which can reduce the risk of positional displacement of the second isolation layer during the charging and discharging process of the electrode assembly, and ensure the isolation of the second isolation layer. Effect.
  • an embodiment of the present application provides a battery cell, including a casing and the electrode assembly according to any embodiment of the first aspect, and the electrode assembly is housed in the casing.
  • the embodiment of the present application provides a battery, including a plurality of battery cells in the second aspect.
  • an embodiment of the present application provides an electrical device, including the battery cell in the second aspect, and the battery cell is used to provide electric energy.
  • Fig. 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application.
  • Fig. 2 is a schematic explosion diagram of a battery provided by some embodiments of the present application.
  • Fig. 3 is a schematic explosion diagram of a battery cell provided by some embodiments of the present application.
  • Fig. 4 is a schematic structural diagram of an electrode assembly provided by some embodiments of the present application.
  • Fig. 5 is a partially enlarged schematic diagram of the electrode assembly shown in Fig. 4;
  • Fig. 6 is the enlarged schematic diagram at block P of Fig. 5;
  • FIG. 7 is a schematic structural view of the electrode assembly shown in FIG. 4 before winding
  • Fig. 8 is a schematic structural diagram of the isolation assembly shown in Fig. 7;
  • Fig. 9 is a schematic structural view of the separator assembly of the electrode assembly provided by other embodiments of the present application before winding;
  • Fig. 10 is a schematic structural diagram of an electrode assembly provided in some other embodiments of the present application.
  • Figure 11 is a partially enlarged schematic view of the electrode assembly shown in Figure 10;
  • Fig. 12 is a schematic structural view of the electrode assembly shown in Fig. 10 before winding;
  • Fig. 13 is a schematic structural view of an electrode assembly provided by another embodiment of the present application before winding;
  • Fig. 14 is a schematic structural diagram of electrode assemblies provided in some further embodiments of the present application.
  • connection In the description of this application, it should be noted that, unless otherwise clearly stipulated and limited, the terms “installation”, “connection”, “connection” and “attachment” should be understood in a broad sense, for example, it may be a fixed connection, It can also be detachably connected or integrally connected; it can be directly connected or indirectly connected through an intermediary, and it can be internal communication between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application according to specific situations.
  • Multiple appearing in this application refers to more than two (including two), similarly, “multiple groups” refers to more than two groups (including two groups), and “multi-piece” refers to more than two (Includes two pieces).
  • the battery cells may include lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium-lithium-ion battery cells, sodium-ion battery cells, or magnesium-ion battery cells, etc.
  • the embodiment of the present application does not limit this.
  • the battery cell can be in the form of a cylinder, a flat body, a cuboid or other shapes, which is not limited in this embodiment of the present application.
  • Battery cells are generally divided into three types according to packaging methods: cylindrical battery cells, square square battery cells and pouch battery cells, which are not limited in this embodiment of the present application.
  • the battery cell includes an electrode assembly and an electrolyte, and the electrode assembly includes a positive pole piece, a negative pole piece and a separator.
  • a battery cell works primarily by moving metal ions between the positive and negative pole pieces.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer is coated on the surface of the positive electrode current collector, and the current collector not coated with the positive electrode active material layer protrudes from the current collector coated with the positive electrode active material layer, The current collector not coated with the positive electrode active material layer is used as the positive electrode tab.
  • the material of the positive electrode current collector can be aluminum, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary lithium or lithium manganate.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is coated on the surface of the negative electrode current collector, and the current collector not coated with the negative electrode active material layer protrudes from the current collector coated with the negative electrode active material layer, The current collector not coated with the negative electrode active material layer is used as the negative electrode tab.
  • the material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon or silicon.
  • the number of positive pole tabs is multiple and stacked together, and the number of negative pole tabs is multiple and stacked together.
  • the material of the spacer can be PP (polypropylene) or PE (polyethylene).
  • the electrode assembly may be a wound structure or a laminated structure, which is not limited in the embodiment of the present application.
  • the battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.
  • the battery mentioned in this application may include a battery module or a battery pack, and the like.
  • Batteries generally include a case for enclosing one or more battery cells. The box can prevent liquid or other foreign objects from affecting the charging or discharging of the battery cells.
  • the separator has electronic insulation, and it is arranged between the positive pole piece and the negative pole piece, and its main function is to prevent the positive pole piece and the negative pole piece from contacting, thereby causing an internal short circuit of the electrode assembly.
  • the separator has a large number of penetrating micropores, which can ensure the free passage of electrolyte ions.
  • the separator has good permeability to lithium ions.
  • the spacer may include an isolation base layer and a functional layer positioned on the surface of the isolation base layer, the isolation base layer may be at least one of polypropylene, polyethylene, ethylene-propylene copolymer, polybutylene terephthalate, etc.,
  • the functional layer may be a mixture layer of ceramic oxide and binder.
  • the separator occupies a very important position in the electrode assembly, which can directly lead to short circuit, performance and life reduction of the electrode assembly.
  • metal ions are extracted from the positive electrode active material layer and inserted into the negative electrode active material layer, but some abnormalities may occur, resulting in the precipitation of metal ions.
  • the extracted lithium ions cannot wait.
  • a large amount of negative electrode active material layer embedded in the negative electrode sheet lithium ions that cannot be embedded in the negative electrode sheet can only obtain electrons on the surface of the negative electrode sheet, thereby forming a simple metal lithium, which is the phenomenon of lithium precipitation.
  • Lithium analysis not only degrades the performance of the battery cell, greatly shortens the cycle life, but also limits the fast charge capacity of the battery cell.
  • the precipitated lithium metal is very active and can react with the electrolyte at a lower temperature, resulting in a decrease in the self-heating start temperature (Tonset) of the battery cell and The rate of self-generated heat increases, seriously endangering the safety of battery cells.
  • Tonset self-heating start temperature
  • the extracted lithium ions can form a lithium layer on the surface of the negative electrode sheet, and the lithium dendrites of the lithium layer may pass through the separator and cause a short circuit between the adjacent positive electrode sheet and the negative electrode sheet, causing safety hazards. Hidden danger.
  • an electrode assembly which includes a positive pole piece, a negative pole piece, and a separator assembly for isolating the positive pole piece and the negative pole piece.
  • the isolation assembly includes a base area and a reinforcement area connected to the base area, the thickness of the reinforcement area is greater than that of the base area; at least part of the reinforcement area is located between adjacent positive and negative pole pieces.
  • the strengthening area can be used to correspond to the position where lithium is easily separated from the negative electrode sheet. In this way, when the negative electrode sheet is releasing lithium, the strengthening area can effectively separate the positive electrode sheet and the negative electrode sheet, reducing the probability of lithium dendrites passing through the isolation component. risk, improving longevity and safety.
  • the base region can have a smaller thickness, which can reduce the amount of isolation components, reduce costs, and increase the energy density of the electrode assembly.
  • the electric device is taken as an example for description.
  • Fig. 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application.
  • a battery 2 is arranged inside the vehicle 1 , and the battery 2 can be arranged at the bottom, head or tail of the vehicle 1 .
  • the battery 2 can be used for power supply of the vehicle 1 , for example, the battery 2 can be used as an operating power source of the vehicle 1 .
  • the vehicle 1 may also include a controller 3 and a motor 4 , the controller 3 is used to control the battery 2 to supply power to the motor 4 , for example, for the starting, navigation and working power requirements of the vehicle 1 during driving.
  • the battery 2 can not only be used as an operating power source for the vehicle 1 , but can also be used as a driving power source for the vehicle 1 to provide driving power for the vehicle 1 instead of or partially replacing fuel oil or natural gas.
  • Fig. 2 is a schematic explosion diagram of a battery provided by some embodiments of the present application.
  • the battery 2 includes a case body 5 and a battery cell 6 , and the battery cell 6 is accommodated in the case body 5 .
  • the box body 5 is used to accommodate the battery cells 6, and the box body 5 may have various structures.
  • the box body 5 may include a first box body part 5a and a second box body part 5b, the first box body part 5a and the second box body part 5b cover each other, the first box body part 5a and the second box body part 5a
  • the two box parts 5b jointly define a receiving space 5c for receiving the battery cells 6 .
  • the second box body part 5b can be a hollow structure with one end open, the first box body part 5a is a plate-shaped structure, and the first box body part 5a covers the opening side of the second box body part 5b to form an accommodating space 5c
  • the box body 5; the first box body portion 5a and the second box body portion 5b also can be a hollow structure with one side opening, and the opening side of the first box body portion 5a is covered on the opening side of the second box body portion 5b , to form a box body 5 with an accommodating space 5c.
  • the first box body part 5a and the second box body part 5b can be in various shapes, such as a cylinder, a cuboid, and the like.
  • a sealant such as sealant, sealing ring, etc., can also be provided between the first box body part 5a and the second box body part 5b. .
  • the first box part 5a covers the top of the second box part 5b
  • the first box part 5a can also be called an upper box cover
  • the second box part 5b can also be called a lower box.
  • battery 2 there are a plurality of battery cells 6 .
  • the plurality of battery cells 6 can be connected in series, in parallel or in parallel.
  • the mixed connection means that the plurality of battery cells 6 are both connected in series and in parallel.
  • a plurality of battery cells 6 can be directly connected in series or in parallel or mixed together, and then the whole composed of a plurality of battery cells 6 is contained in the box body 5; of course, a plurality of battery cells 6 can also be connected in series first Or parallel or mixed connection to form a battery module, multiple battery modules are then connected in series or parallel or mixed to form a whole, and accommodated in the box 5 .
  • FIG. 3 is an exploded schematic diagram of a battery cell provided by some embodiments of the present application.
  • the battery cell 6 refers to the smallest unit constituting the battery 2 . As shown in FIG. 3 , the battery cell 6 includes a casing 20 , an electrode assembly 10 and other functional components, and the electrode assembly 10 is accommodated in the casing 20 .
  • housing 20 includes end cap 22 and housing 21 .
  • the end cap 22 refers to a component that covers the opening of the housing 21 to isolate the internal environment of the battery cell 6 from the external environment.
  • the shape of the end cap 22 can be adapted to the shape of the housing 21 to fit the housing 21 .
  • the end cap 22 can be made of a material (such as aluminum alloy) with a certain hardness and strength, so that the end cap 22 is not easy to deform when being squeezed and collided, so that the battery cell 6 can have a higher Structural strength and safety performance can also be improved.
  • Functional components such as electrode terminals 30 may be provided on the end cap 22 .
  • the electrode terminal 30 can be used to be electrically connected with the electrode assembly 10 for outputting or inputting electric energy of the battery cell 6.
  • the end cover 22 may also be provided with a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 6 reaches a threshold value.
  • the material of the end cap 22 can also be various, for example, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which is not particularly limited in this embodiment of the present application.
  • an insulator can be provided inside the end cover 22 , and the insulator can be used to isolate the electrical connection components in the housing 21 from the end cover 22 to reduce the risk of short circuit.
  • the insulating member may be plastic, rubber or the like.
  • the casing 21 is a component used to cooperate with the end cap 22 to form the internal environment of the battery cell 6 , wherein the formed internal environment can be used to accommodate the electrode assembly 10 , electrolyte and other components.
  • the housing 21 and the end cover 22 can be independent components, and an opening can be provided on the housing 21 , and the internal environment of the battery cell 6 can be formed by making the end cover 22 cover the opening at the opening.
  • the end cover 22 and the housing 21 can also be integrated. Specifically, the end cover 22 and the housing 21 can form a common connection surface before other components are inserted into the housing. When the inside of the housing 21 needs to be encapsulated , then make the end cover 22 cover the housing 21.
  • the housing 21 can be in various shapes and sizes, such as cuboid, cylinder, hexagonal prism and so on. Specifically, the shape of the casing 21 can be determined according to the specific shape and size of the electrode assembly 10 .
  • the housing 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which is not particularly limited in this embodiment of the present application.
  • the electrode assembly 10 is a part of the battery cell 6 that is soaked in an electrolyte solution to undergo an electrochemical reaction.
  • the housing 21 may contain one or more electrode assemblies 10 .
  • the electrode assembly 10 is mainly formed by winding a positive pole piece and a negative pole piece, and usually a separator is provided between the positive pole piece and the negative pole piece.
  • the parts of the positive pole piece and the negative pole piece with the active material constitute the main body of the electrode assembly 10 , and the parts of the positive pole piece and the negative pole piece without the active material respectively form tabs.
  • the positive pole tab and the negative pole tab can be located at one end of the main body together or at two ends of the main body respectively.
  • Figure 4 is a schematic structural view of an electrode assembly provided in some embodiments of the present application
  • Figure 5 is a partially enlarged schematic view of the electrode assembly shown in Figure 4
  • Figure 6 is an enlarged schematic view of Figure 5 at box P
  • Figure 7 is a schematic view of Figure 4
  • FIG. 8 is the structural schematic view of the separator assembly shown in FIG. 7 .
  • the electrode assembly 10 of the embodiment of the present application includes a positive pole piece 11 , a negative pole piece 12 and a separator 13 , and the separator 13 is used to isolate the positive pole piece 11 and the negative pole piece 12 .
  • the isolation assembly 13 includes a base area 13b and a reinforcement area 13a connected to the base area 13b, the thickness of the reinforcement area 13a is greater than the thickness of the base area 13b; at least part of the reinforcement area 13a is located between the adjacent positive pole piece 11 and the negative pole piece 12 between.
  • the electrode assembly 10 can be in various shapes, for example, the electrode assembly 10 can be in the shape of a cylinder, a flat body, a prism (such as a triangular prism, a quadrangular prism or a hexagonal prism) or other shapes.
  • a prism such as a triangular prism, a quadrangular prism or a hexagonal prism
  • isolation components 13 there can be one or more isolation components 13 .
  • only one isolation component 13 may be provided with a reinforcement area 13a, or each isolation assembly 13 may be provided with a reinforcement area 13a.
  • the separator assembly 13 is an assembly including an insulating film for isolating the positive pole piece 11 and the negative pole piece 12 .
  • This insulating film has a large number of penetrating micropores, which can ensure the free passage of metal ions; for example, the insulating film has good permeability to lithium ions, and basically cannot block the passage of lithium ions.
  • the isolation component 13 may be made of one insulating film, or may be made of multiple insulating films.
  • reinforcement region 13a There may be one reinforcement region 13a, or there may be a plurality of reinforcement regions. Exemplarily, there are multiple reinforcing regions 13a, and adjacent reinforcing regions 13a are connected through the base region 13b.
  • the reinforcement area 13 a can be located entirely between the positive pole piece 11 and the negative pole piece 12 , or only partly between the positive pole piece 11 and the negative pole piece 12 .
  • the reinforced area 13a can be used to correspond to the position where lithium is easily separated from the negative pole piece 12. In this way, when the negative pole piece 12 is freed from lithium, the reinforced area 13a can effectively separate the positive pole piece 11 and the negative pole piece 12, reducing lithium branching. The risk of crystal passing through the isolation component 13 is reduced, and the life and safety are improved.
  • the base region 13b can have a smaller thickness, which can reduce the amount of the isolation component 13, reduce the cost, and increase the energy density of the electrode assembly 10.
  • the thickness of the reinforced region 13a is 2 ⁇ m-100 ⁇ m.
  • the thickness of the reinforced region 13a is 2 ⁇ m, 5 ⁇ m, 7 ⁇ m, 10 ⁇ m, 12 ⁇ m, 20 ⁇ m, 30 ⁇ m, 50 ⁇ m, 80 ⁇ m or 100 ⁇ m.
  • the greater the thickness of the reinforced region 13 a the lower the energy density of the electrode assembly 10 , but the lower the risk of the reinforced region 13 a being penetrated by lithium dendrites, the higher the safety of the electrode assembly 10 .
  • the inventors limited the thickness of the reinforced region 13 a to 2 ⁇ m-100 ⁇ m in order to balance the energy density and safety of the electrode assembly 10 .
  • the thickness of the reinforced region 13a is 5 ⁇ m-30 ⁇ m.
  • the reinforcing region 13a is configured as a multi-layer structure
  • the base region 13b is configured as a single-layer structure.
  • a plurality of isolation layers are stacked together to form a multilayer structure.
  • the stacking direction of the plurality of isolation layers is parallel to the stacking direction of the positive electrode sheet 11 and the negative electrode sheet 12 .
  • two adjacent isolation layers may be connected to each other, or may be separated from each other.
  • the thickness of the reinforcement region 13a refers to the sum of the thicknesses of multiple isolation layers.
  • the number of layers in the reinforcement zone 13a is greater than or equal to two. Exemplarily, the number of layers of the reinforced area 13a may be 2-15.
  • the isolation layer is a single layer.
  • both the base body region 13b and the reinforcement region 13a are plural, and the plurality of base body regions 13b and the plurality of reinforcement regions 13a are arranged alternately along the winding direction W.
  • the base region 13b is used to correspond to the position of the negative electrode sheet 12 where lithium is not easily separated.
  • the matrix region 13b has fewer layers, which can reduce the amount of the isolation component 13 and increase the energy density of the battery cell.
  • the lithium layer When the lithium layer is precipitated on the surface of the negative electrode sheet 12, the lithium layer will squeeze the isolation layer near the negative electrode sheet 12 in the strengthening region 13a, and the isolation layer near the negative electrode sheet 12 will be stretched under the extrusion of the lithium layer.
  • the pore size of the micropores in the separation layer near the negative electrode sheet 12 becomes larger and a defect region is formed, the smaller lithium dendrites in the lithium layer may pass through the defect region.
  • the isolation layer of the strengthening region 13a away from the negative electrode sheet 12 can insulate and isolate the lithium dendrites passing through the defect region from the positive electrode sheet 11, thereby reducing the risk of lithium dendrites contacting the positive electrode sheet 11 and providing safety.
  • the distance between the isolation layer far away from the negative electrode sheet 12 and the lithium layer in the strengthening region 13a is relatively large, and the extrusion force of the lithium layer is relatively small, and the risk of stretching and generating defect regions under the extrusion force is also small. .
  • the position of the defect region produced by the separator in the stretching process is uncertain, even the defect region is produced in the separator far away from the negative pole piece 12, and the defect region of the separator far away from the negative pole piece 12 is the same as that near the negative pole piece 12. It is very unlikely that the defect regions of the isolation layer are opposite to each other, and it is more difficult for lithium dendrites to pass through the strengthening region 13a at the same time. Therefore, the embodiment of the present application can effectively reduce the risk of short circuit and improve safety by providing the reinforced region 13a.
  • the reinforced region 13a with a multi-layer structure can more effectively block lithium dendrites, reduce the risk of short circuit, and improve safety.
  • the protection effect of the reinforced region 13 a composed of two 5 ⁇ m isolation layers is better than the protection effect of the reinforced region 13 a composed of a single 10 ⁇ m isolation layer.
  • the reinforced region 13a with a multi-layer structure can adopt a smaller thickness, which can reduce the amount of the isolation component 13 and improve the electrode assembly 10. energy density.
  • the positive pole piece 11 , the separator assembly 13 and the negative pole piece 12 are wound to form a bending area B, and at least part of the reinforcing area 13 a is disposed in the bending area B.
  • the winding direction W is the circumferential winding direction of the positive pole piece 11 , the negative pole piece 12 and the separator assembly 13 from the inside to the outside.
  • the winding direction W is counterclockwise.
  • the bending region B is a region having a bending structure in the electrode assembly 10 , and in the bending region B, the positive pole piece 11 , the negative pole piece 12 and the separator assembly 13 are all bent.
  • the part of the positive pole piece 11 located in the bending area B is generally bent into an arc shape
  • the part of the negative pole piece 12 located in the bending area B is generally bent into an arc shape.
  • each circle can be constructed with several layers, and one circle refers to a certain point on the electrode assembly 10 as the starting point to start counting , along the winding direction W one week to reach another point to locate the end end, the end end and the start end and the center of the circle are on a straight line, and the start end is between the end end and the center of the circle.
  • the electrode assembly 10 can be bent region B as a whole, or only part of the region can be bent region B.
  • the electrolytic assembly includes a straight region A and a bent region B, the bent region B is connected to the straight region A, and the straight region A is a region of the electrode assembly 10 having a straight structure.
  • the reinforcing area 13a may be entirely disposed in the bending area B, or may be only partially disposed in the bending area B. As shown in FIG.
  • the positive pole piece 11 and the negative pole piece 12 located in the bending area B need to be bent, and the positive active material layer and the negative active material layer are prone to stress concentration during the bending process and cause their respective active materials to fall off. Due to the coming off of the active material, especially the coming off of the active material on the negative electrode sheet 12, the lithium intercalation position of the negative electrode active material layer of the negative electrode sheet 12 may be less than that of the positive electrode active material layer of its adjacent positive electrode sheet 11. The amount of lithium ions provided, thus triggering the phenomenon of lithium precipitation.
  • at least part of the strengthening region 13a is set in the bending region B.
  • the strengthening region 13a can also block lithium dendrites, reducing the size of the positive electrode sheet 11 and the negative electrode sheet. 12 conduction probability, effectively reducing the risk of short circuit and improving the service life and safety of the electrode assembly 10 .
  • the positive pole piece 11 includes a first bent portion 111 located in the bent area B and adjacent to the reinforcement region 13a
  • the negative pole piece 12 includes a second bent portion adjacent to the first bent portion 111 Section 121.
  • the reinforcement area 13 a includes a plurality of bent layers 14 located in the bent area B and stacked between the first bent portion 111 and the second bent portion 121 .
  • Adjacent to the first bent portion 111 and the second bent portion 121 means that there is no other layer of positive electrode sheet or another layer of negative electrode sheet between them.
  • the reinforcement area 13a is adjacent to the first bent portion 111 means that there is no other layer of positive electrode sheet or another layer of negative electrode sheet between them.
  • the positive electrode sheet 11 includes a plurality of positive electrode bending portions 11 a located in the bending region B, and the positive electrode bending portion 11 a adjacent to the reinforcement region 13 a having a multi-layer structure is the first bending portion 111 .
  • part of the positive electrode bending portion 11 a may be the first bending portion 111 , or all the positive electrode bending portions 11 a may be the first bending portion 111 .
  • the negative electrode tab 12 includes a plurality of negative electrode bending parts located in the bending area B.
  • the negative electrode bending part adjacent to the first bending part 111 and sandwiching the reinforcement area 13a with the first bending part 111 is The second bending part 121 .
  • the reinforced area 13a and the second bent portion 121 may be provided only on the inner side of the first bent portion 111, or the reinforced area 13a and the second bent portion may be provided only on the outer side of the first bent portion 111. part 121 , the reinforcing area 13 a and the second bending part 121 may also be provided on both sides of the first bending part 111 .
  • the plurality of bending layers 14 can block lithium dendrites when lithium is separated in the second bending portion 121 , reduce the risk of lithium dendrites contacting the first bending portion 111 , and improve safety.
  • At least the inner side of the first bent portion 111 is provided with a reinforcing area 13 a and a second bent portion 121 .
  • the curvature of the second bent portion 121 located inside the first bent portion 111 is greater than that of the first bent portion 111, so the second bent portion 121 is more prone to shedding of the active material during the bending process, that is, In other words, the second bent portion 121 inside the first bent portion 111 is more prone to lithium deposition.
  • the reinforced region 13a can separate the first bent part 111 from the second bent part 121 located inside the first bent part 111, and even if the second bent part 121 is decomposing lithium, it can also reduce lithium dendrites passing through the reinforced area. The probability of zone 13a reduces the risk of short circuit and improves safety.
  • the first bent portion 111 includes a first collector portion 1111 and a first active material layer 1112 disposed on the surface of the first collector portion 1111 , and the thickness of the first active material layer 1112 is h1.
  • the second bent part 121 includes a second collector part 1211 and a second active material layer 1212 disposed on the surface of the second collector part 1211, the thickness of the second active material layer 1212 is h2, and the thickness of the bent layer 14 is h3 , the thickness of the second collector portion 1211 is h4.
  • the maximum distance between the first bent portion 111 and the second bent portion 121 is X.
  • the number of layers of the bending layer 14 located between the first bending portion 111 and the second bending portion 121 is Y, and Y is a positive integer greater than 1.
  • the active material capacity per unit area of the first active material layer 1112 is A1
  • the active material capacity per unit area of the second active material layer 1212 is A2.
  • the first current collector 1111 may be a part of the positive electrode current collector, and the first active material layer 1112 is a part of the positive electrode active material layer.
  • the second current collector 1211 may be a part of the negative electrode current collector, and the second active material layer 1212 is a part of the negative electrode active material layer.
  • the maximum distance between the surface of the first bent portion 111 facing the second bent portion 121 and the surface of the second bent portion 121 facing the first bent portion 111 is X .
  • the thickness direction of the first bent portion 111 may be the normal direction of the surface of the first bent portion 111 facing the second bent portion 121 .
  • the active material capacity per unit area A1 of the first active material layer 1112 is the ratio of the active material capacity of the first active material layer 1112 to the area of the surface of the first collector 1111 coated with the first active material layer 1112 .
  • the active material capacity A2 per unit area of the second active material layer 1212 is the ratio of the active material capacity of the second active material layer 1212 to the area of the surface of the second current collecting portion 1211 coated with the second active material layer 1212 .
  • EC+DMC+DEC ethylene carbonate, dimethyl carbonate, and dicarbonate with a volume ratio of 1:1:1 dissolved in LiPF Ethyl ester
  • the average value of the discharge capacity of the six button cells is the average discharge capacity of the first active material layer 1112 on one side, which can be used as the active material capacity A1 per unit area of the first active material layer 1112 .
  • the positive electrode active material is lithium iron phosphate
  • the upper limit cut-off voltage x 1 V 3.75V
  • the lower limit cut-off voltage y 1 V 2V
  • the positive electrode active material is lithium nickel cobalt manganese oxide (NCM)
  • the upper limit cut-off voltage x 1 V 4.25V
  • the lower limit cut-off voltage y 1 V 2.8V.
  • EC+DMC+DEC ethylene carbonate, dimethyl carbonate, and dicarbonate with a volume ratio of 1:1:1 dissolved in LiPF Ethyl ester
  • the average charging capacity of the six button cells is the average charging capacity of the second active material layer 1212 on one side, which can be used as the active material capacity A2 per unit area of the second active material layer 1212 .
  • the negative electrode active material is graphite
  • the upper limit cut-off voltage x 2 V 2V
  • the lower limit cut-off voltage y 2 V 5mV.
  • the negative electrode active material is silicon
  • the upper limit cut-off voltage x 2 V 2V
  • the lower limit cut-off voltage y 2 V 5mV.
  • the fewer layers of the bending layer 14 in the strengthening region 13a, the higher the risk of lithium dendrites passing through the strengthening region 13a; the more layers of the bending layer 14 in the strengthening region 13a, the more complex the structure of the isolation component 13, and the electrode The energy density of the assembly 10 is lower.
  • the inventors set the number of bent layers 14 according to the above formula to balance the safety and energy density of the electrode assembly 10 .
  • the lithium intercalation space of the second active material layer 1212 is insufficient, and the lithium ions extracted from the first active material layer 1112 cannot be inserted into the second active material layer 1212 in equal amounts, and cannot be inserted into the second active material layer 1212 Lithium ions can only obtain electrons on the surface of the second active material layer 1212, so that the phenomenon of lithium precipitation occurs.
  • the electrode assembly 10 with A2/A1 ⁇ 1 has a more severe lithium deposition phenomenon, and the bending layer 14 in the strengthening region 13a needs more layers.
  • the inventors set the number of bent layers 14 according to the above formula to balance the safety and energy density of the electrode assembly 10 .
  • h1 has a value of 5 ⁇ m-80 ⁇ m.
  • the value of h1 is 5 ⁇ m, 10 ⁇ m, 20 ⁇ m, 30 ⁇ m, 50 ⁇ m or 80 ⁇ m.
  • h2 has a value of 10 ⁇ m-100 ⁇ m.
  • the value of h2 is 10 ⁇ m, 20 ⁇ m, 30 ⁇ m, 50 ⁇ m, 80 ⁇ m or 100 ⁇ m.
  • the value of h3 is 1 ⁇ m-20 ⁇ m.
  • the value of h3 is 1 ⁇ m, 3 ⁇ m, 5 ⁇ m, 10 ⁇ m, 15 ⁇ m or 20 ⁇ m.
  • the inventors set the value of h3 to be less than or equal to 20 ⁇ m to ensure the energy density of the electrode assembly 10 .
  • the value of h4 is 2 ⁇ m-20 ⁇ m, optionally, the value of h4 may be 2 ⁇ m, 3 ⁇ m, 5 ⁇ m, 10 ⁇ m, 15 ⁇ m or 20 ⁇ m.
  • the value of X is from 10 ⁇ m to 5000 ⁇ m.
  • the value of X may be 10 ⁇ m, 20 ⁇ m, 50 ⁇ m, 100 ⁇ m, 500 ⁇ m, 1000 ⁇ m, 2000 ⁇ m or 5000 ⁇ m.
  • the positive electrode sheet 11 includes a plurality of positive electrode bending parts 11a arranged along the winding direction W, at least the positive electrode bending part 11a formed by the first bending of the positive electrode sheet 11 is set as the first bend Fold part 111. That is to say, the positive electrode bending portion 11 a formed by the first bending of the positive electrode sheet 11 is disposed adjacent to the reinforcement region 13 a.
  • the plurality of positive electrode bending portions 11a of the positive electrode sheet 11 are all bent.
  • the positive electrode bending portion 11a is generally arc-shaped.
  • the positive electrode bending portion 11 a formed by the first bending of the positive electrode sheet 11 refers to the positive electrode bending portion 11 a formed by the first bending of the positive electrode sheet 11 during winding along the winding direction W.
  • the curvature of the positive electrode bending portion 11a formed by the first bending of the positive electrode sheet 11 is relatively large.
  • the negative electrode adjacent to the positive electrode bending portion 11a formed by the first bending of the positive electrode sheet 11 The pole piece 12 is more prone to the problem of lithium precipitation.
  • the positive bending part 11a formed by the first bending of the positive electrode piece 11 is set as the first bending part 111, so that the reinforcement area 13a can effectively bend the positive electrode piece 11 for the first time.
  • the formed positive electrode bending portion 11a is isolated from lithium dendrites, reducing the risk of short circuit and improving safety.
  • the positive bent portion 11 a formed by the second bending of the positive electrode sheet 11 is also set as the first bent portion 111 . That is to say, the positive electrode bending portion 11 a formed by the second bending of the positive electrode sheet 11 is also disposed adjacent to the reinforcement region 13 a.
  • the positive electrode bending portion 11a formed by the second bending of the positive electrode sheet 11 refers to the positive electrode bending portion 11a formed by the second bending of the positive electrode sheet 11 during the winding process along the winding direction W.
  • the reinforcement region 13a adjacent to the positive bending portion 11a formed by the first bending of the positive electrode sheet 11 may be reinforced adjacent to the positive bending portion 11a formed by the second bending of the positive electrode sheet 11.
  • the regions 13a are connected as a whole, or may be arranged at intervals along the winding direction W.
  • the curvature of the positive electrode bending portion 11a formed by the second bending of the positive electrode sheet 11 is relatively large.
  • the negative electrode adjacent to the positive electrode bending portion 11a formed by the second bending of the positive electrode sheet 11 The pole piece 12 is prone to the problem of lithium precipitation.
  • the positive bending portion 11a formed by the second bending of the positive electrode sheet 11 is set as the first bending portion 111, so that the reinforced area 13a can effectively bend the positive electrode sheet 11 for the second time.
  • the formed positive electrode bending portion 11a is isolated from lithium dendrites, reducing the risk of short circuit and improving safety.
  • the total thickness of the reinforcement area 13a inside the positive bending portion 11a formed by the first bending of the positive electrode piece 11 is T1
  • the total thickness of the reinforcement area 13a inside the positive bent portion 11a is T2, T1 ⁇ T2.
  • the curvature of the second bent portion 121 located inside the positive bent portion 11a formed by the first bending of the positive electrode piece 11 is greater than that of the inner side of the positive bent portion 11a formed by the second bent of the positive electrode piece 11
  • the curvature of the second bent portion 121, the second bent portion 121 located inside the positive electrode bent portion 11a formed by the first bending of the positive electrode sheet 11 is easier to precipitate lithium.
  • T1 ⁇ T2 is set so as to reduce the risk that the positive electrode bending portion 11a formed by the first bending of the positive electrode sheet 11 is connected to the lithium dendrite, and improve the safety of the battery cell.
  • the number of layers of the isolation layer in the reinforcing region 13a inside the positive bending part 11a formed by the first bending of the positive electrode sheet 11 is L1
  • the layer number of the isolation layer at the second bending of the positive electrode sheet 11 is The number of isolation layers formed in the reinforcing region 13a inside the positive electrode bending portion 11a is L2, and L1 ⁇ L2.
  • both sides of the first bending portion 111 are provided with a reinforcing area 13a and a second bending portion 121, and the total thickness of the reinforcing area 13a inside the first bending portion 111 is greater than or equal to that of the first bending portion 111.
  • the total thickness of the reinforced area 13 a outside the bent portion 111 is provided.
  • the reinforcement regions 13 a on both sides of the first bent portion 111 may belong to the same isolation assembly 13 , or may belong to two different isolation assemblies 13 respectively.
  • the curvature of the second bent portion 121 located inside the first bent portion 111 is greater than the curvature of the second bent portion 121 located outside the first bent portion 111 , and the second bent portion 121 located inside the first bent portion 111
  • the bent portion 121 is more prone to lithium precipitation.
  • the thickness of the reinforced region 13a located inside the first bent portion 111 is not smaller than the thickness of the reinforced region 13a located outside the first bent portion 111, so as to reduce the conduction between the first bent portion 111 and the lithium dendrite. risk and improve the safety of battery cells.
  • the number of isolation layers in the reinforced area 13a located inside the first bending portion 111 is greater than or equal to the number of isolation layers in the reinforced area 13a located outside the first bent portion 111 .
  • the positive electrode piece 11 , the separator assembly 13 and the negative electrode piece 12 are wound to form a straight region A, and the straight region A is connected to the bent region B. At least part of the base region 13b is disposed in the flat region A. As shown in FIG.
  • the flat area A is the area where the electrode assembly 10 has a flat structure, and the parts of the positive electrode sheet 11 and the negative electrode sheet 12 located in the flat area A are substantially flat.
  • the surface of each layer of positive electrode sheet 11 and the surface of each layer of negative electrode sheet 12 located in the flat region A are substantially planar.
  • Both the positive pole piece 11 and the negative pole piece 12 located in the flat area A are in a straight state, the active material in the flat area A is not easy to fall off, and the negative pole piece 12 located in the flat area A is not prone to the problem of lithium precipitation. Therefore, Even if the base region 13b is set in the flat region A, the insulation between the positive and negative electrodes can be improved and the risk of short circuit can be reduced.
  • both ends of the reinforcing area 13a along the winding direction W are located in the straight area A, so that the reinforcing area 13a can pass through the bending area B entirely, thereby reducing the risk of short circuit in the bending area B.
  • the tail end of the reinforcing area 13a exceeds the bending area B by 3mm-500mm.
  • the tail end of the reinforcement area 13a exceeds the bending area B by 10mm-100mm.
  • the isolation assembly 13 includes a first isolation layer 131 and a second isolation layer 132, the first isolation layer 131 is used to insulate and isolate the positive electrode sheet 11 and the negative electrode sheet 12, and at least part of the second isolation layer 132 It is located between the positive pole piece 11 and the negative pole piece 12 and laminated with the first isolation layer 131 .
  • the area of the first isolation layer 131 that overlaps with the second isolation layer 132 and the second isolation layer 132 form the reinforcement area 13a of the isolation assembly 13, and the area of the first isolation layer 131 that does not overlap with the second isolation layer 132 forms the base area 13b .
  • the first isolation layer 131 can be understood as a layer of isolation layer between the positive electrode sheet 11 and the negative electrode sheet 12 in the related art, that is, the basic isolation layer, and the second isolation layer 132 can be understood as an additional isolation layer. layer, the additional isolation layer.
  • isolation assembly 13 there may be one or more second isolation layers 132 .
  • the first isolation layer 131 and the second isolation layer 132 can be two parts of an integrated component, or can be two independent components provided separately.
  • the first isolation layer 131 and the second isolation layer 132 can be made of the same material or different materials.
  • the thickness of the first isolation layer 131 and the thickness of the second isolation layer 132 are not limited, and the thickness of the first isolation layer 131 may be greater than, equal to, or smaller than the thickness of the second isolation layer 132 .
  • the first isolation layer 131 and the second isolation layer 132 are stacked between the positive electrode sheet 11 and the negative electrode sheet 12 .
  • the second isolation layer 132 can be independently arranged on the first isolation layer 131, that is, in the stacking direction of the first isolation layer 131 and the second isolation layer 132, the surface of the second isolation layer 132 facing the first isolation layer 131 is in contact with the first isolation layer 131. There is no connection relationship such as adhesion between the isolation layers 131 .
  • the second isolation layer 132 can also be attached to the surface of the first isolation layer 131.
  • the second isolation layer 132 can be attached to the first isolation layer 131 as a whole, or only partially attached to the first isolation layer 131.
  • Layer 131. Attached refers to an attached connection.
  • a second isolation layer 132 is additionally added to the electrode assembly 10 to form a reinforced region 13 a with a larger thickness on the isolation assembly 13 , thereby reducing the risk of short circuit caused by lithium precipitation and improving safety.
  • the number of layers of the second isolation layer 132 is 1-10.
  • the number of layers of the second isolation layer 132 is 1, 2, 3, 5 or 10.
  • the dimensions of the multiple second isolation layers 132 along the winding direction W may be the same or different.
  • the isolation component 13 there are multiple reinforced regions 13 a of the isolation component 13 , and the number of layers of the second isolation layer 132 in the reinforced regions 13 a may be the same or different.
  • the thickness of the second isolation layer 132 is less than or equal to the thickness of the first isolation layer 131 .
  • the first isolation layer 131 and the second isolation layer 132 can play the function of multi-layer protection, so the increased second isolation layer 132 can have the thickness not greater than the first isolation layer 131, to reduce the consumption of the second isolation layer 132 .
  • the thickness of the second isolation layer 132 is smaller than the thickness of the first isolation layer 131 .
  • the second isolation layer 132 is disposed on a side of the first isolation layer 131 facing the positive electrode sheet 11 .
  • the thickness of the first isolation layer 131 is 2 ⁇ m-30 ⁇ m.
  • the thickness of the first isolation layer 131 is 2 ⁇ m, 5 ⁇ m, 7 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m or 30 ⁇ m.
  • the thickness of the second isolation layer 132 is 1 ⁇ m-25 ⁇ m.
  • the thickness of the second isolation layer 132 is 1 ⁇ m, 2 ⁇ m, 5 ⁇ m, 7 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m or 25 ⁇ m.
  • the porosity of the second isolation layer 132 is smaller than that of the first isolation layer 131 . Since the second isolation layer 132 has a smaller porosity, after the lithium dendrites pass through the first isolation layer 131, the lithium dendrites are not easy to pass through the micropores in the second isolation layer 132, thereby reducing the density of the lithium dendrites. The risk of conduction with the positive pole piece 11 improves safety.
  • the second isolation layer 132 is a porous structure, and the diameter of the pores in the second isolation layer 132 is less than or equal to 1 ⁇ m.
  • the aperture of the pores in the second isolation layer 132 is small, and the lithium dendrites are not easy to pass through, thereby reducing the risk of conduction between the lithium dendrites and the positive electrode sheet 11 and improving safety.
  • the first isolation layer 131 includes a base film 133 and an insulating layer 134 coated on a surface of the base film 133 .
  • the base film 133 may be a porous film.
  • the base film 133 is made of an electrically insulating and liquid-retaining polymer material, such as PP (polypropylene), PE (polyethylene) or PVDF (polyvinylidene fluoride).
  • the insulating layer 134 is a functional layer disposed on the surface of the base film 133 .
  • the insulating layer 134 includes an inorganic material, a polymer binder and a dispersion agent, the inorganic material may include at least one of boehmite and silicon dioxide, and the polymer binder may include PVDF and polystyrene-acrylic acid At least one of the esters, the dispersant may include polyvinyl alcohol.
  • the inorganic material can clamp the base film 133 to reduce shrinkage of the base film 133 .
  • the polymer binder can be bonded to the pole pieces, increasing the overall rigidity of the electrode assembly 10 .
  • the second isolation layer 132 may include only the base film 133 , or may include both the base film 133 and the insulating layer 134 .
  • the base film 133 of the second isolation layer 132 is integrated with the base film 133 of the first isolation layer 131 .
  • the number of layers of the reinforcement region 13 a is determined by the number of layers of the base film 133 .
  • the number of layers in the reinforcement area 13a refers to the number of layers of the base film 133 in the reinforcement area 13a.
  • the thickness of the insulating layer 134 is 0.5 ⁇ m-10 ⁇ m.
  • the particle size of the inorganic material is 0.1 ⁇ m-10 ⁇ m.
  • the content of the inorganic material in the insulating layer 134 is 70%-98%, the content of the polymer binder is 1%-20%, and the content of the dispersant is 0.5%-10%.
  • At least part of the second isolation layer 132 is disposed separately from the first isolation layer 131 .
  • At least part of the second isolation layer 132 has no connection relationship with the first isolation layer 131 such as adhesion.
  • this embodiment can effectively reduce the risk of lithium dendrites passing through the first isolation layer 131 and the second isolation layer 132 , and improve safety.
  • the positive electrode sheet 11, the separator assembly 13 and the negative electrode sheet 12 are wound to form a bent area B and a straight area A, and the straight area A is connected to the bent area B.
  • a part of the second isolation layer 132 is located in the bending area B, and another part of the second isolation layer 132 is located in the flat area A.
  • the bent area B the second isolation layer 132 is separated from the first isolation layer 131 ; in the straight area A, the second isolation layer 132 is attached to the first isolation layer 131 .
  • the risk of lithium precipitation in the bending area B is relatively high, and the second isolation layer 132 in the bending area B is separated from the first isolation layer 131, which can effectively reduce the penetration of lithium dendrites through the first isolation layer 131 and the second isolation layer. 132 risks, improving security.
  • the second isolation layer 132 is attached to the first isolation layer 131 , which can reduce the movement range of the second isolation layer 132 along the winding direction W, and reduce the risk of dislocation of the second isolation layer 132 .
  • the second isolation layer 132 is formed by folding the end of the first isolation layer 131 .
  • the end of the first isolation layer 131 is folded to form the second isolation layer 132 , and the fold is the boundary between the first isolation layer 131 and the second isolation layer 132 .
  • the second isolation layer 132 extends directly from the end of the first isolation layer 131, without adding and fixing the second isolation layer 132 separately, so that the winding process is more convenient, and the integrity of the electrode assembly 10 is improved. good.
  • the positive electrode sheet 11, the separator assembly 13 and the negative electrode sheet 12 are wound, the electrode assembly 10 includes a starting section 100 along the winding direction W, and the end of the first separator layer 131 is located at the starting section 100.
  • the starting section 100 along the winding direction W refers to the end of the electrode assembly 10 located in the innermost circle.
  • the second isolation layer 132 can extend from the starting section 100 along the winding direction W and pass through the positive electrode bending part 11a formed by the first bending of the positive electrode sheet 11, which can reduce lithium dendrites and pass through the first isolation layer at the same time. 131 and the second isolation layer 132 and the risk of contact with the positive electrode bending portion 11a of the positive electrode tab 11, improving safety. At the same time, this embodiment can also reduce the length that the second isolation layer 132 needs to extend, saving the amount and reducing the cost.
  • the positive pole piece 11, the separator assembly 13 and the negative pole piece 12 are wound to form a bending area B, and the bending area B includes a first bending position B1 close to the starting section 100 along the winding direction W , the first bending portion B1 is provided with a first isolation layer 131 and a second isolation layer 132, and the second isolation layer 132 extends from the end of the first isolation layer 131 and beyond the first bending portion B1.
  • the first bending position B1 is the position where the electrode assembly 10 is bent for the first time during the winding forming process. Exemplarily, at the first bending position B1, the positive pole piece 11 is bent for the first time, and the negative pole piece 12 is bent for the first time.
  • the second isolation layer 132 extends beyond the first bending part B1.
  • the first isolation layer 131 and the second isolation layer 132 can at least protect the first bending part B1, which is most prone to the problem of lithium precipitation, and can also save the second isolation layer.
  • the use of the layer 132 improves the safety and service life of the electrode assembly 10 while saving costs.
  • Fig. 9 is a schematic structural view of the separator assembly of the electrode assembly provided by other embodiments of the present application before winding.
  • the isolation component 13 is a single-layer structure as a whole.
  • the reinforcing region 13a and the base region 13b having different thicknesses are directly formed.
  • Fig. 10 is a schematic structural view of an electrode assembly provided by some other embodiments of the present application
  • Fig. 11 is a partially enlarged schematic view of the electrode assembly shown in Fig. 10
  • Fig. 12 is a schematic structural view of the electrode assembly shown in Fig. 10 before winding.
  • the multiple reinforcement regions 13a may respectively correspond to the multiple positive bending portions 11a of the positive electrode sheet 11, so as to reduce the risk of short circuit in the multiple positive electrode bending portions 11a of the positive electrode sheet 11 and improve safety.
  • Each reinforced region 13 a includes one or more second isolation layers 132 .
  • the number of layers of the multiple reinforced regions 13a may be the same or different.
  • each reinforcement region 13 a can isolate one positive bend 11 a from one negative bend of the negative tab 12 .
  • the positive pole piece 11 , the separator 13 and the negative pole piece 12 are wound to form the bending region B.
  • the bending area B includes a plurality of bending positions arranged along the winding direction W
  • the electrode assembly 10 includes a plurality of second isolation layers 132
  • the first isolation layer 131 and the plurality of second isolation layers 132 are arranged in the plurality of bending positions. at least one of the
  • the bent portion is the position where the electrode assembly 10 is bent during the winding forming process.
  • the multiple bending positions include a first bending position B1 and a second bending position B2, at the first bending position B1, both the positive pole piece 11 and the negative pole piece 12 are bent for the first time, and In the second bending position B2, both the positive pole piece 11 and the negative pole piece 12 are bent for the second time.
  • the second isolation layer 132 is provided at part or all of the multiple bending locations, which can effectively reduce the risk of short circuit at the bending locations and improve safety.
  • one of the second isolation layers 132 may be configured to extend through multiple bending positions, or each second isolation layer 132 may be configured to extend through one bending position.
  • a plurality of second isolation layers 132 are arranged at intervals.
  • the plurality of second isolation layers 132 are arranged at intervals, it can be understood that the plurality of second isolation layers 132 are not connected as a whole piece of second isolation layer 132, but split.
  • This embodiment can make the setting mode of the second isolation layer 132 more flexible, that is, the second isolation layer 132 can be arbitrarily set to the position where the number of isolation layers needs to be increased, and it can also reduce the number of isolation layers due to the need to increase the number of isolation layers.
  • the waste caused by adding the second isolation layer 132 at the position increases the energy density.
  • the electrode assembly 10 includes an initial section 100 along the winding direction W. As shown in FIG.
  • the plurality of bending positions include a first bending position B1 and a second bending position B2, and along the winding direction W, the first bending position B1 is closer to the starting section 100 than the second bending position B2.
  • the thickness of the second isolation layer 132 disposed at the first bending position B1 is greater than the thickness of the second isolation layer 132 disposed at the second bending position B2.
  • the risk of lithium deposition at the negative electrode sheet 12 at the first bending position B1 is higher than the risk of lithium deposition at the negative electrode sheet 12 at the second bending position B2, and lithium dendrites pass through the second isolation layer at the first bending position B1 132 is higher than the risk of lithium dendrites passing through the second isolation layer 132 at the second bending position B2. Therefore, in this embodiment, the thickness of the second isolation layer 132 disposed at the first bending position B1 is greater than that at the The thickness of the second isolation layer 132 at the second bending portion B2 is to enhance protection at the first bending portion B1 which is more likely to be short-circuited, improve safety, and save the amount of the second isolation layer 132 .
  • multiple second isolation layers 132 are bonded to the surface of the first isolation layer 131, which can reduce the risk of positional displacement of the second isolation layer 132 during the charging and discharging process of the electrode assembly 10, and ensure the second The isolation effect of the isolation layer 132.
  • both ends of the second isolation layer 132 along the winding direction W are bonded to the first isolation layer 131 , and the middle part of the second isolation layer 132 along the winding direction W is separated from the first isolation layer 131 .
  • the electrode assembly 10 is thermally pressed from the outside, so that the second isolation layer 132 is bonded to the first isolation layer 131 .
  • the first isolation layer 131 includes two surfaces along its thickness direction, and the plurality of second isolation layers 132 are located on the same surface of the first isolation layer 131 .
  • Second isolation layers 132 are arranged on the same surface of the first isolation layer 131. When the first isolation layer 131 is tensioned, the influence of the second isolation layer 132 on the distance between the positive pole piece 11 and the negative pole piece 12 is reduced, the risk of lithium deposition is reduced, and the safety is improved.
  • Fig. 13 is a schematic structural view of an electrode assembly provided by some other embodiments of the present application before winding.
  • the thicknesses of the reinforcement regions 13 a gradually decrease from the inside to the outside.
  • the thickness of the innermost reinforced region 13a is greater than the thickness of the outermost reinforced region 13a.
  • the thicknesses of two adjacent reinforcing regions 13a may be the same or different.
  • the thickness of the reinforced region 13a can be increased in areas with high short-circuit risk, and the thickness of the reinforced region 13a can be reduced in areas with low short-circuit risk, which can improve safety and save the amount of isolation components 13 .
  • the thickness difference between adjacent reinforcing regions 13 a is 0.5 ⁇ m-10 ⁇ m.
  • the thickness difference between adjacent reinforcing regions 13a is 0.5 ⁇ m, 1 ⁇ m, 2 ⁇ m, 5 ⁇ m, 7 ⁇ m or 10 ⁇ m.
  • Fig. 14 is a schematic structural diagram of electrode assemblies provided in some further embodiments of the present application.
  • the positive electrode sheet 11 includes a plurality of positive electrode bending portions 11 a arranged along the winding direction W, at least the positive electrode bending portion 11 a formed by the last bending of the positive electrode sheet 11 It is set as the first bent portion 111 .
  • the electrode assembly 10 expands and squeezes the case during charging, and the case exerts a reaction force on the electrode assembly 10 .
  • the region of the negative electrode sheet 12 opposite to the positive electrode bending portion 11a formed by the last bending of the positive electrode sheet 11 is prone to lithium precipitation under the action of the reaction force.
  • at least part of the reinforcement area 13a is adjacent to the positive bending portion 11a formed by the last bending of the positive electrode sheet 11, so as to reduce the positive electrode bending portion 11a formed by the last bending of the positive electrode sheet 11. The risk of conduction with lithium dendrites improves the safety of battery cells.
  • the electrode assembly 10 is cylindrical.
  • Each positive electrode bending portion 11 a of the positive electrode sheet 11 refers to a circle of positive electrode sheets.
  • the present application also provides a battery cell, which includes a casing and the electrode assembly of any one of the above embodiments, and the electrode assembly is accommodated in the casing.
  • the present application also provides a battery, including a plurality of battery cells in any one of the above embodiments.
  • the present application also provides an electric device, including the battery cell in any one of the above embodiments, and the battery cell is used to provide electric energy for the electric device.
  • the electrical device may be any of the aforementioned devices or systems using battery cells.
  • the present application provides an electrode assembly 10, which includes a positive pole piece 11, a negative pole piece 12 and an isolation assembly 13, and the isolation assembly 13 is used to isolate the positive pole piece. 11 and negative pole piece 12.
  • the isolation assembly 13 includes a first isolation layer 131 and a second isolation layer 132.
  • the first isolation layer 131 is used to insulate and isolate the positive pole piece 11 and the negative pole piece 12.
  • At least part of the second isolation layer 132 is located between the positive pole piece 11 and the negative pole piece 12.
  • the negative electrode sheets 12 are laminated with the first isolation layer 131 .
  • the region of the first isolation layer 131 that overlaps with the second isolation layer 132 and the second isolation layer 132 form the reinforced area 13a of the isolation assembly 13, and the area of the first isolation layer 131 that does not overlap with the second isolation layer 132 forms the isolation assembly 13
  • the base region 13b, the thickness of the reinforcement region 13a is greater than the thickness of the base region 13b.
  • the second isolation layer 132 is formed by folding the ends of the first isolation layer 131 .
  • the positive electrode piece 11 , the separator assembly 13 and the negative electrode piece 12 are wound to form a bent area B and a straight area A, and the straight area A is connected to the bent area B. At least a part of the reinforcement area 13a is disposed in the bent area B, and at least a portion of the base area 13b is disposed in the straight area A.
  • a part of the reinforcement area 13a is adjacent to the positive electrode bending part 11a formed by the first bending of the positive electrode sheet 11, and the other part of the reinforcement area 13a is adjacent to the positive electrode bending part 11a formed by the second bending of the positive electrode sheet 11.
  • the folded portions 11a are adjacently provided.
  • Embodiment 1 can be prepared according to the following steps:
  • the spacer component includes a first spacer layer and a second spacer layer, and the length of the second spacer layer is 652.5 mm.
  • the area of the first isolation layer overlapping with the second isolation layer and the second isolation layer form the reinforced area of the isolation assembly, the area of the first isolation layer that does not overlap with the second isolation layer forms the matrix area of the isolation assembly, the thickness of the reinforcement area is 14 ⁇ m, and the thickness of the base region is 7 ⁇ m.
  • the electrode assembly into the square casing, and weld the casing and the end cap; then go through the processes of liquid injection, standing, forming, shaping, etc., to obtain the battery cell.
  • the capacity of the battery cell is 60Ah.
  • step (v) the gap between the innermost circle of positive pole pieces and the innermost circle of negative pole pieces is artificially made 200 ⁇ m, so as to accelerate the lithium deposition of the electrode assembly.
  • a first separation layer and a second separation layer are provided between the innermost circle of positive pole pieces and the innermost circle of negative pole pieces.
  • the preparation method of the battery cell of Example 2 refers to Example 1, the difference is that: in step (vi), artificially divide the positive pole pieces between the innermost two circles of positive pole pieces and the innermost two circles of negative pole pieces
  • the gap is 200 ⁇ m
  • the length of the second isolation layer is 873.6 mm
  • the first isolation layer and the second isolation layer are also arranged between the second circle of positive pole pieces and the second circle of negative pole pieces.
  • the preparation method of the battery cell of Comparative Example 1 refers to that of Example 1, except that the separator of Comparative Example 1 is not folded, and the separator has a single-layer structure.
  • the preparation method of the battery cell of Comparative Example 2 refers to that of Example 2, except that the separator of Comparative Example 2 is not folded, and the separator has a single-layer structure.
  • Example 1, Example 2, Comparative Example 1 and Comparative Example 2 prepared 80 battery cells, and each battery cell was tested.
  • the battery cell is charged at a rate of 1C, discharged at a rate of 1C, and cyclically charged and discharged in a high SOC (eg, 0.9-1) range.
  • a high SOC eg, 0.9-1
  • the 40 battery cells in Example 1 were fully charged after 500 cycles, and then left to stand for 24 hours to detect the voltage drop of the battery cells, and calculate the self-discharge rate of each battery cell, and then calculate the average value.
  • the self-discharge rate is voltage drop/time.
  • the remaining 40 battery cells in Example 1 were subjected to 2000 cycles, and the number of battery cells that failed was recorded during the cycle, and the failure rate was calculated.
  • Example 2 Comparative Example 1, and Comparative Example 2 were also tested according to the above steps.
  • Example 1-2 and Comparative Example 1-2 setting a strengthening area between the positive electrode sheet and the negative electrode sheet can reduce the risk of short circuit and improve the service life of the battery cell when lithium is separated from the negative electrode sheet.

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Abstract

本申请实施例提供一种电极组件、电池单体、电池以及用电装置。电极组件包括正极极片、负极极片和隔离组件，隔离组件用于隔离正极极片和负极极片。隔离组件包括基体区和连接于基体区的加强区，加强区的厚度大于基体区的厚度。加强区的至少部分位于相邻的正极极片和负极极片之间。加强区可用于与负极极片的容易析锂的位置相对应，这样，当负极极片析锂时，加强区能够有效地分隔正极极片和负极极片，降低锂枝晶穿过隔离组件的风险，提高寿命和安全性。相对于加强区，基体区可具有较小的厚度，这样可以减少隔离组件的用量，降低成本，提高电极组件的能量密度。

Description

电极组件、电池单体、电池以及用电装置
相关申请的交叉引用
本申请要求享有于2021年09月10日提交的名称为“电极组件及与其相关的电池单体、电池、装置和制造方法”的中国专利申请202111062600.7的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请涉及电池技术领域，并且更具体地，涉及一种电极组件、电池单体、电池以及用电装置。
背景技术
电池单体广泛用于电子设备，例如手机、笔记本电脑、电瓶车、电动汽车、电动飞机、电动轮船、电动玩具汽车、电动玩具轮船、电动玩具飞机和电动工具等等。电池单体可以包括镉镍电池单体、氢镍电池单体、锂离子电池单体和二次碱性锌锰电池单体等。
在电池技术的发展中，如何提高电池单体的安全性，是电池技术中的一个研究方向。
发明内容
本申请提供了一种电极组件、电池单体、电池以及用电装置，其能提高安全性。
第一方面，本申请实施例提供了一种电极组件，包括正极极片、负极极片和隔离组件，隔离组件用于隔离正极极片和负极极片。隔离组件包括基体区和连接于基体区的加强区，加强区的厚度大于基体区的厚度。加强区的至少部分位于相邻的正极极片和负极极片之间。
在上述技术方案中，加强区可用于与负极极片的容易析锂的位置相对应，这样，当负极极片析锂时，加强区能够有效地分隔正极极片和负极极片，降低锂枝晶穿过隔离组件的风险，提高寿命和安全性。相对于加强区，基体区可具有较小的厚度，这样可以减少隔离组件的用量，降低成本，提高电极组件的能量密度。
在一些实施例中，加强区的厚度为2μm-100μm。
加强区的厚度越小，电极组件的能量密度越高，但加强区被锂枝晶穿过的风险越高。加强区的厚度越大，电极组件的能量密度越低，但加强区被锂枝晶穿过的风险越低，电极组件的安全性越高。上述技术方案将加强区的厚度限制在2μm-100μm，以 平衡电极组件的能量密度和安全性。
在一些实施例中，正极极片、隔离组件和负极极片经过卷绕形成弯折区域，加强区的至少部分设置于弯折区域。
上述技术方案将加强区的至少部分设置于容易析锂的弯折区域，即使弯折区域出现了析锂的情况，加强区也能够阻挡锂枝晶，减小正极极片和负极极片导通的概率，有效地降低短路风险，提高电极组件的使用寿命和安全性。
在一些实施例中，正极极片包括位于弯折区域并与加强区相邻的第一弯折部，负极极片包括与第一弯折部相邻的第二弯折部。加强区包括多个弯折层，多个弯折层位于弯折区域并层叠于第一弯折部和第二弯折部之间。
在上述技术方案中，多个弯折层可以在第二弯折部析锂时阻挡锂枝晶，降低锂枝晶与第一弯折部接触的风险，提高安全性。
在一些实施例中，第一弯折部的至少内侧设有加强区和第二弯折部。
位于第一弯折部内侧的第二弯折部的曲率大于第一弯折部的曲率，所以第二弯折部在弯折的过程中更容易出现活性物质的脱落，也就是说，第一弯折部内侧的第二弯折部更容易出现析锂。上述技术方案的加强区能够将第一弯折部和位于第一弯折部内侧的第二弯折部隔开，即使第二弯折部析锂，也能够减小锂枝晶穿过加强区的概率，降低短路风险，提高安全性。
在一些实施例中，第一弯折部包括第一集流部和设置于第一集流部表面的第一活性物质层，第一活性物质层的厚度为h1。第二弯折部包括第二集流部和设置于第二集流部表面的第二活性物质层，第二活性物质层的厚度为h2，弯折层的厚度为h3，第二集流部的厚度为h4。在第一弯折部的厚度方向上，第一弯折部和第二弯折部之间的最大间距为X。位于第一弯折部和第二弯折部之间的弯折层的层数为Y，Y为大于1的正整数。第一活性物质层的单位面积活性物质容量为A1，第二活性物质层的单位面积活性物质容量为A2，A2/A1≥1。h1、h2、h3、h4、X以及Y满足：
Figure PCTCN2022094258-appb-000001
加强区的弯折层的层数越少，锂枝晶穿过加强区的风险越高；加强区的弯折层的层数越多，隔离组件的结构越复杂，电极组件的能量密度越低。上述技术方案可根据上述公式设置弯折层的层数，以平衡电极组件的安全性和能量密度。
在一些实施例中，第一弯折部包括第一集流部和设置于第一集流部表面的第一活性物质层，第一活性物质层的厚度为h1。第二弯折部包括第二集流部和设置于第二集流部表面的第二活性物质层，第二活性物质层的厚度为h2，弯折层的厚度为h3，第二集流部的厚度为h4。在第一弯折部的厚度方向上，第一弯折部和第二弯折部之间的最大间距为X。位于第一弯折部和第二弯折部之间的弯折层的层数为Y，Y为大于1的正整数。第一活性物质层的单位面积活性物质容量为A1，第二活性物质层的单位面积活性物质容量为A2，A2/A1＜1。h1、h2、h3、h4、X以及Y满足：
Figure PCTCN2022094258-appb-000002
在上述技术方案中，可根据上述公式设置弯折层的层数，以平衡电极组件的安全性和能量密度。
在一些实施例中，h3的值为1μm-20μm，以平衡电极组件的安全性和能量密度。
在一些实施例中，X的值为10μm-5000μm。
在一些实施例中，正极极片包括沿卷绕方向设置的多个正极弯折部，至少正极极片的第一次弯折所形成的正极弯折部设置为第一弯折部。
正极极片的第一次弯折所形成的正极弯折部的曲率较大，在充电时，与正极极片的第一次弯折所形成的正极弯折部相邻的负极极片更容易出现析锂问题。上述技术方案将正极极片的第一次弯折所形成的正极弯折部设置为第一弯折部，以使加强区能够有效地将正极极片的第一次弯折所形成的正极弯折部与锂枝晶隔离，降低短路风险，提高安全性。
在一些实施例中，正极极片的第二次弯折所形成的正极弯折部也设置为第一弯折部。
上述技术方案将正极极片的第二次弯折所形成的正极弯折部设置为第一弯折部，以使加强区能够有效地将正极极片的第二次弯折所形成的正极弯折部与锂枝晶隔离，降低短路风险，提高安全性。
在一些实施例中，位于正极极片的第一次弯折所形成的正极弯折部内侧的加强区的总厚度为T1，位于正极极片的第二次弯折所形成的正极弯折部内侧的加强区的总厚度为T2，T1≥T2。
上述技术方案使T1≥T2，以降低正极极片的第一次弯折所形成的正极弯折部与锂枝晶导通的风险，提高电池单体的安全性。
在一些实施例中，第一弯折部的两侧均设置有加强区和第二弯折部，位于第一弯折部内侧的加强区的总厚度大于或等于位于第一弯折部外侧的加强区的总厚度，以降低第一弯折部与锂枝晶导通的风险，提高电池单体的安全性。
在一些实施例中，正极极片包括沿卷绕方向设置的多个正极弯折部，至少正极极片的最后一次弯折所形成的正极弯折部设置为第一弯折部，以降低正极极片的最后一次弯折所形成的正极弯折部与锂枝晶导通的风险，提高电池单体的安全性。
在一些实施例中，正极极片、隔离组件和负极极片经过卷绕还形成平直区域，平直区域连接于弯折区域。基体区的至少部分设置于平直区域。
位于平直区域的正极极片和负极极片均处于平直状态，平直区域的活性物质的不易脱落，位于平直区域的负极极片不易出现析锂问题，因此，即使上述技术方案将基体区设置到平直区域，也能改善正负极片之间的绝缘性，降低短路风险。
在一些实施例中，加强区和基体区均设置为多个，多个加强区和多个基体区沿卷绕方向交替设置。
在上述技术方案中，多个加强区可以分别与正极极片的多个正极弯折部对应，以降低正极极片的多个正极弯折部出现短路风险，提高安全性。
在一些实施例中，沿卷绕方向，多个加强区的厚度从内到外逐渐减小。
沿卷绕方向，正极极片的从内到外的正极弯折部的曲率逐渐减小，与锂枝晶接触的风险也逐渐降低。上述技术方案这可以在短路风险高的区域增大加强区的厚度，在短路风险低的区域减小加强区的厚度，这样可以提高安全性，并节省隔离组件的用量。
在一些实施例中，沿卷绕方向，相邻的加强区的厚度差为0.5μm-10μm。
在一些实施例中，加强区设置为多层结构，基体区设置为单层结构。
在上述技术方案中，在厚度相同的前提下，相较于具有单层结构的加强区，具有多层结构的加强区能够更有效地阻挡锂枝晶，降低短路风险，提高安全性。在满足强度要求的前提下，相较于具有单层结构的加强区，具有多层结构的加强区可以采用较小的厚度，这样可以减少隔离组件的用量，提高电极组件的能量密度。
在一些实施例中，隔离组件包括第一隔离层和第二隔离层，第一隔离层用于将正极极片和负极极片绝缘隔离，第二隔离层的至少部分位于正极极片和负极极片之间并与第一隔离层层叠。第一隔离层的与第二隔离层重叠的区域以及第二隔离层形成隔离组件的加强区，第一隔离层的不与第二隔离层重叠的区域形成基体区。
在上述技术方案中，在电极组件中额外附加第二隔离层，以在隔离组件上形成具有较大厚度的加强区，从而降低因析锂引发的短路风险，提高安全性。
在一些实施例中，第二隔离层的厚度小于或者等于第一隔离层的厚度。
在上述技术方案中，第一隔离层和第二隔离层可以起到多层防护的功能，所以增加的第二隔离层可以具有不大于第一隔离层的厚度，以减小第二隔离层的用量。
在一些实施例中，在第一隔离层和第二隔离层的层叠方向上，第二隔离层的至少部分与第一隔离层分离设置。
当第一隔离层在锂层的挤压下拉伸时，第二隔离层与第一隔离层分离的部分受到来自第一隔离层的影响较小，第二隔离层拉伸的程度较小，产生缺陷的风险较低。上述技术方案可以有效地降低锂枝晶穿过第一隔离层和第二隔离层的风险，提高安全性。
在一些实施例中，正极极片、隔离组件和负极极片经过卷绕形成弯折区域和平直区域，平直区域连接于弯折区域。第二隔离层的一部分位于弯折区域，第二隔离层的另一部分位于平直区域。在弯折区域，第二隔离层与第一隔离层分离设置。在平直区域，第二隔离层附接于第一隔离层。
在上述技术方案中，弯折区域析锂的风险较高，将弯折区域的第二隔离层与第一隔离层分离设置，可以有效地降低锂枝晶穿过第一隔离层和第二隔离层的风险，提高安全性。在平直区域，第二隔离层附接于第一隔离层，可以减小第二隔离层沿卷绕方向的移动幅度，降低第二隔离层错位的风险。
在一些实施例中，第二隔离层由第一隔离层的端部折叠而成。
在上述技术方案中，使第二隔离层直接从第一隔离层的端部开始延伸，无需单独进行增加和固定第二隔离层，从而使得卷绕过程更为方便，电极组件的一体性更好。
在一些实施例中，正极极片、隔离组件和负极极片卷绕设置，电极组件包括沿卷绕方向的起始段，第一隔离层的端部位于起始段。
在上述技术方案中，第二隔离层可以从起始段沿卷绕方向延伸并经过正极极片第一次弯折所形成的正极弯折部，可减小锂枝晶同时穿过第一隔离层和第二隔离层并与正极极片的正极弯折部接触的风险，提高安全性，还可以减小第二隔离层需要延伸的长度，节省用量，降低成本。
在一些实施例中，正极极片、隔离组件和负极极片经过卷绕形成弯折区域，弯折区域包括沿卷绕方向靠近起始段的第一弯折部位，第一弯折部位设置有第一隔离层和第二隔离层，第二隔离层从第一隔离层的端部延伸并超出第一弯折部位。
在上述技术方案中，在第一弯折部位，正极极片和负极极片弯折的曲率最大，在充电时，负极极片出现析锂的风险最高。第二隔离层延伸并超出第一弯折部位，第一隔离层和第二隔离层至少能够保护最容易出现析锂问题的第一弯折部位，同时还能够节省第二隔离层的使用，从而在节约成本的同时，提高电极组件的安全性和使用寿命。
在一些实施例中，正极极片、隔离组件和负极极片经过卷绕形成弯折区域。弯折区域包括沿卷绕方向设置的多个弯折部位，电极组件包括多个第二隔离层，第一隔离层和多个第二隔离层设置于多个弯折部位中的至少一个。
在上述技术方案中，在多个弯折部位中的部分或全部位置设置第二隔离层，能够有效地降低弯折部位短路的风险，提高安全性。
在一些实施例中，沿卷绕方向，多个第二隔离层间隔设置。
上述技术方案可以使得第二隔离层的设置方式更为灵活，即可以任意将第二隔离层设置到需要增加隔离层层数的位置，同时也可减少因在不需要增加隔离层层数的位置增加第二隔离层而造成的浪费，提高能量密度。
在一些实施例中，电极组件包括沿卷绕方向的起始段。多个弯折部位包括第一弯折部位和第二弯折部位，沿卷绕方向，第一弯折部位比第二弯折部位更靠近起始段。设置在第一弯折部位的第二隔离层的厚度大于设置在第二弯折部位的第二隔离层的厚度。
上述技术方案可以在更容易短路的第一弯折部位加强防护，提高安全性，并节省第二隔离层的用量。
在一些实施例中，第一隔离层包括沿自身厚度方向的两个表面，多个第二隔离层位于第一隔离层的同一表面，以在第一隔离层张紧时，减小第二隔离层对正极极片和负极极片之间的间距的影响，降低析锂风险，提高安全性。
在一些实施例中，多个第二隔离层粘接于第一隔离层的表面，可以降低第二隔离层在电极组件的充放电过程中发生位置偏移的风险，保证第二隔离层的隔离效果。
第二方面，本申请实施例提供了一种电池单体，包括外壳和第一方面任一实施例的电极组件，电极组件容纳于外壳内。
第三方面，本申请实施例提供了一种电池，包括多个第二方面的电池单体。
第四方面，本申请实施例提供了一种用电装置，包括第二方面的电池单体，电池单体用于提供电能。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需要使用的附图作简单地介绍，显而易见地，下面所描述的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据附图获得其他的附图。
图1为本申请一些实施例提供的车辆的结构示意图；
图2为本申请一些实施例提供的电池的爆炸示意图；
图3为本申请一些实施例提供的电池单体的爆炸示意图；
图4为本申请一些实施例提供的电极组件的结构示意图；
图5为图4所示的电极组件的局部放大示意图；
图6为图5在方框P处的放大示意图；
图7为图4所示的电极组件在卷绕前的结构示意图；
图8为图7所示的隔离组件的结构示意图；
图9为本申请另一些实施例提供的电极组件的隔离组件在卷绕前的结构示意图；
图10为本申请又一些实施例提供的电极组件的结构示意图；
图11为图10所示的电极组件的局部放大示意图；
图12为图10所示的电极组件在卷绕前的结构示意图；
图13为本申请又一些实施例提供的电极组件在卷绕前的结构示意图；
图14为本申请再一些实施例提供的电极组件的结构示意图。
具体实施方式的附图标记如下：
1、车辆；2、电池；3、控制器；4、马达；5、箱体；5a、第一箱体部；5b、第二箱体部；5c、容纳空间；6、电池单体；10、电极组件；100、起始段；20、外壳；21、壳体；22、端盖；30、电极端子；11、正极极片；111、第一弯折部；1111、第一集流部；1112、第一活性物质层；11a、正极弯折部；12、负极极片；121、第二弯折部；1211、第二集流部；1212、第二活性物质层；13、隔离组件；131、第一隔离层；132、第二隔离层；133、基膜；134、绝缘层；13a、加强区；13b、基体区；14、弯折层；A、平直区域；B、弯折区域；B1、第一弯折部位；B2、第二弯折部位；W、卷绕方向。
具体实施方式
为使本申请实施例的目的、技术方案和优点更加清楚，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本申请一部分实施例，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在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
除非另有定义，本文所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同；本文中在申请的说明书中所使用的术语只是为了描 述具体的实施例的目的，不是旨在于限制本申请；本申请的说明书和权利要求书及上述附图说明中的术语“包括”和“具有”以及它们的任何变形，意图在于覆盖不排他的包含。本申请的说明书和权利要求书或上述附图中的术语“第一”、“第二”等是用于区别不同对象，而不是用于描述特定顺序或主次关系。
在本申请的描述中，需要理解的是，术语“中心”、“横向”、“长度”、“宽度”、“上”、“下”、“前”、“后”、“左”、“右”、“竖直”、“水平”、“顶”、“底”、“内”、“外”、“轴向”、“径向”、“周向”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。
在本申请的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”、“附接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本申请中的具体含义。
在本文中提及“实施例”意味着，结合实施例描述的特定特征、结构或特性可以包含在本申请的至少一个实施例中。在说明书中的各个位置出现该短语并不一定均是指相同的实施例，也不是与其它实施例互斥的独立的或备选的实施例。本领域技术人员显式地和隐式地理解的是，本文所描述的实施例可以与其它实施例相结合。
本文中术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
本申请中出现的“多个”指的是两个以上(包括两个)，同理，“多组”指的是两组以上(包括两组)，“多片”指的是两片以上(包括两片)。
本申请中，电池单体可以包括锂离子二次电池单体、锂离子一次电池单体、锂硫电池单体、钠锂离子电池单体、钠离子电池单体或镁离子电池单体等，本申请实施例对此并不限定。电池单体可呈圆柱体、扁平体、长方体或其它形状等，本申请实施例对此也不限定。电池单体一般按封装的方式分成三种：柱形电池单体、方体方形电池单体和软包电池单体，本申请实施例对此也不限定。
电池单体包括电极组件和电解质，电极组件包括正极极片、负极极片和隔离件。电池单体主要依靠金属离子在正极极片和负极极片之间移动来工作。正极极片包括正极集流体和正极活性物质层，正极活性物质层涂覆于正极集流体的表面，未涂敷正极活性物质层的集流体凸出于已涂覆正极活性物质层的集流体，未涂敷正极活性物质层的集流体作为正极极耳。以锂离子电池为例，正极集流体的材料可以为铝，正极活性物质可以为钴酸锂、磷酸铁锂、三元锂或锰酸锂等。负极极片包括负极集流体和负极活性物质层，负极活性物质层涂覆于负极集流体的表面，未涂敷负极活性物质层的集流体凸出于已涂覆负极活性物质层的集流体，未涂敷负极活性物质层的集流体作为负极极耳。负极集流体的材料可以为铜，负极活性物质可以为碳或硅等。为了保证通过 大电流而不发生熔断，正极极耳的数量为多个且层叠在一起，负极极耳的数量为多个且层叠在一起。隔离件的材质可以为PP(聚丙烯)或PE(聚乙烯)等。电极组件可以是卷绕式结构，也可以是叠片式结构，本申请实施例并不限于此。电池技术的发展要同时考虑多方面的设计因素，例如，能量密度、循环寿命、放电容量、充放电倍率等性能参数，另外，还需要考虑电池的安全性。
本申请的实施例所提到的电池是指包括一个或多个电池单体以提供更高的电压和容量的单一的物理模块。例如，本申请中所提到的电池可以包括电池模块或电池包等。电池一般包括用于封装一个或多个电池单体的箱体。箱体可以避免液体或其他异物影响电池单体的充电或放电。
隔离件具有电子绝缘性，其设置于正极极片和负极极片之间，其主要作用是防止正极极片和负极极片相接触，进而造成电极组件发生内部短路。隔离件具有大量的贯通的微孔，能够保证电解质离子自由通过，特别地，隔离件对锂离子有很好的透过性。示例性地，隔离件可包括隔离基层和位于隔离基层表面的功能层，隔离基层可以是聚丙烯、聚乙烯、乙烯—丙烯共聚物、聚对苯二甲酸丁二醇酯等的至少一种，功能层可以是陶瓷氧化物和粘结剂的混合物层。
隔离件在电极组件中占有十分重要的地位，可以直接导致电极组件发生短路、性能及寿命降低等现象。
电池单体在充电时，金属离子从正极活性物质层脱出并嵌入负极活性物质层，但是可能会发生一些异常情况，导致金属离子的析出。以锂离子电池单体为例，由于负极活性物质层嵌锂空间不足、锂离子嵌入负极活性物质层阻力太大或锂离子过快的从正极活性物质层脱出等原因，脱出的锂离子无法等量的嵌入负极极片的负极活性物质层，无法嵌入负极极片的锂离子只能在负极极片表面得电子，从而形成金属锂单质，这就是析锂现象。析锂不仅使电池单体性能下降，循环寿命大幅缩短，还限制了电池单体的快充容量。除此之外，电池单体发生析锂时，析出来的锂金属非常活泼，在较低的温度下便可以与电解液发生反应，造成电池单体自产热起始温度(Tonset)降低和自产热速率增大，严重危害电池单体的安全。再者，析锂严重时，脱出的锂离子可以在负极极片表面形成锂层，锂层的锂枝晶可能会穿过隔离件并造成相邻的正极极片和负极极片短路，引发安全隐患。
发明人尝试整体增大隔离件的厚度，以降低锂枝晶穿过隔离件的风险。然而，增大隔离件的厚度会降低电极组件的能量密度。
发明人注意到，在充放电的过程中，负极极片仅部分区域容易出现严重析锂，换言之，负极极片的一部分区域不易析锂或轻微析锂，与这部分区域相对的隔离件无需加厚。
鉴于此，本申请的发明人提出了一种电极组件，其包括正极极片、负极极片和隔离组件，隔离组件用于隔离正极极片和负极极片。隔离组件包括基体区和连接于基体区的加强区，加强区的厚度大于基体区的厚度；加强区的至少部分位于相邻的正极极片和负极极片之间。加强区可用于与负极极片的容易析锂的位置相对应，这样，当负极极片析锂时，加强区能够有效地分隔正极极片和负极极片，降低锂枝晶穿过隔离 组件的风险，提高寿命和安全性。相对于加强区，基体区可具有较小的厚度，这样可以减少隔离组件的用量，降低成本，提高电极组件的能量密度。
以下实施例为了方便说明，以用电装置为车辆为例进行说明。
图1为本申请一些实施例提供的车辆的结构示意图。如图1所示，车辆1的内部设置有电池2，电池2可以设置在车辆1的底部或头部或尾部。电池2可以用于车辆1的供电，例如，电池2可以作为车辆1的操作电源。
车辆1还可以包括控制器3和马达4，控制器3用来控制电池2为马达4供电，例如，用于车辆1的启动、导航和行驶时的工作用电需求。
在本申请一些实施例中，电池2不仅仅可以作为车辆1的操作电源，还可以作为车辆1的驱动电源，代替或部分地代替燃油或天然气为车辆1提供驱动动力。
图2为本申请一些实施例提供的电池的爆炸示意图。如图2所示，电池2包括箱体5和电池单体6，电池单体6容纳于箱体5内。
箱体5用于容纳电池单体6，箱体5可以是多种结构。在一些实施例中，箱体5可以包括第一箱体部5a和第二箱体部5b，第一箱体部5a与第二箱体部5b相互盖合，第一箱体部5a和第二箱体部5b共同限定出用于容纳电池单体6的容纳空间5c。第二箱体部5b可以是一端开口的空心结构，第一箱体部5a为板状结构，第一箱体部5a盖合于第二箱体部5b的开口侧，以形成具有容纳空间5c的箱体5；第一箱体部5a和第二箱体部5b也均可以是一侧开口的空心结构，第一箱体部5a的开口侧盖合于第二箱体部5b的开口侧，以形成具有容纳空间5c的箱体5。当然，第一箱体部5a和第二箱体部5b可以是多种形状，比如，圆柱体、长方体等。
为提高第一箱体部5a与第二箱体部5b连接后的密封性，第一箱体部5a与第二箱体部5b之间也可以设置密封件，比如，密封胶、密封圈等。
假设第一箱体部5a盖合于第二箱体部5b的顶部，第一箱体部5a亦可称之为上箱盖，第二箱体部5b亦可称之为下箱体。
在电池2中，电池单体6为多个。多个电池单体6之间可串联或并联或混联，混联是指多个电池单体6中既有串联又有并联。多个电池单体6之间可直接串联或并联或混联在一起，再将多个电池单体6构成的整体容纳于箱体5内；当然，也可以是多个电池单体6先串联或并联或混联组成电池模块，多个电池模块再串联或并联或混联形成一个整体，并容纳于箱体5内。
图3为本申请一些实施例提供的电池单体的爆炸示意图。
电池单体6是指组成电池2的最小单元。如图3所示，电池单体6包括外壳20、电极组件10以及其他的功能性部件，电极组件10容纳于外壳20内。
在一些实施例中，外壳20包括端盖22和壳体21。
端盖22是指盖合于壳体21的开口处以将电池单体6的内部环境隔绝于外部环境的部件。不限地，端盖22的形状可以与壳体21的形状相适应以配合壳体21。可选地，端盖22可以由具有一定硬度和强度的材质(如铝合金)制成，这样，端盖22在受挤压碰撞时就不易发生形变，使电池单体6能够具备更高的结构强度，安全性能也可以有所提高。端盖22上可以设置有如电极端子30等的功能性部件。电极端子30可以 用于与电极组件10电连接，以用于输出或输入电池单体6的电能。
在一些实施例中，端盖22上还可以设置有用于在电池单体6的内部压力或温度达到阈值时泄放内部压力的泄压机构。端盖22的材质也可以是多种的，比如，铜、铁、铝、不锈钢、铝合金、塑胶等，本申请实施例对此不作特殊限制。
在一些实施例中，在端盖22的内侧还可以设置有绝缘件，绝缘件可以用于隔离壳体21内的电连接部件与端盖22，以降低短路的风险。示例性的，绝缘件可以是塑料、橡胶等。
壳体21是用于配合端盖22以形成电池单体6的内部环境的组件，其中，形成的内部环境可以用于容纳电极组件10、电解液以及其他部件。壳体21和端盖22可以是独立的部件，可以于壳体21上设置开口，通过在开口处使端盖22盖合开口以形成电池单体6的内部环境。不限地，也可以使端盖22和壳体21一体化，具体地，端盖22和壳体21可以在其他部件入壳前先形成一个共同的连接面，当需要封装壳体21的内部时，再使端盖22盖合壳体21。壳体21可以是多种形状和多种尺寸的，例如长方体形、圆柱体形、六棱柱形等。具体地，壳体21的形状可以根据电极组件10的具体形状和尺寸大小来确定。壳体21的材质可以是多种，比如，铜、铁、铝、不锈钢、铝合金、塑胶等，本申请实施例对此不作特殊限制。
电极组件10是电池单体6中浸润于电解液以发生电化学反应的部件。壳体21内可以包含一个或多个电极组件10。电极组件10主要由正极极片和负极极片卷绕形成，并且通常在正极极片与负极极片之间设隔离件。正极极片和负极极片具有活性物质的部分构成电极组件10的主体部，正极极片和负极极片不具有活性物质的部分各自构成极耳。正极极耳和负极极耳可以共同位于主体部的一端或是分别位于主体部的两端。在电池单体6的充放电过程中，正极活性物质和负极活性物质与电解液发生反应，极耳连接电极端子30以形成电流回路。
图4为本申请一些实施例提供的电极组件的结构示意图；图5为图4所示的电极组件的局部放大示意图；图6为图5在方框P处的放大示意图；图7为图4所示的电极组件在卷绕前的结构示意图；图8为图7所示的隔离组件的结构示意图。
如图4至图8所示，本申请实施例的电极组件10包括正极极片11、负极极片12和隔离组件13，隔离组件13用于隔离正极极片11和负极极片12。隔离组件13包括基体区13b和连接于基体区13b的加强区13a，加强区13a的厚度大于基体区13b的厚度；加强区13a的至少部分位于相邻的正极极片11和负极极片12之间。
电极组件10可以是多种形状，例如，电极组件10可呈圆柱体、扁平体、棱柱体(例如三棱柱、四棱柱或六棱柱)或其它形状。
隔离组件13可以是一个，也可以是多个。示例性地，隔离组件13设置为两个，本申请可以先将一个隔离组件13、负极极片12、另一个隔离组件13和正极极片11依次层叠，然后再卷绕两圈以上以形成卷绕结构。当隔离组件13设置为多个时，可以是仅一个隔离组件13设有加强区13a，也可以是每个隔离组件13均设有加强区13a。
隔离组件13是一种包括绝缘膜的组件，用于隔离正极极片11和负极极片12。这种绝缘膜具有大量贯通的微孔，能够保证金属离子自由通过；示例性地，绝缘膜对 锂离子有很好的透过性，基本上不能阻挡锂离子通过。
示例性地，隔离组件13可以由一张绝缘膜制成，也可以由多张绝缘膜制成。
加强区13a可以是一个，也可以是多个。示例性地，加强区13a为多个，相邻的加强区13a通过基体区13b相连。
加强区13a可以整体位于正极极片11和负极极片12之间，也可以仅部分位于正极极片11和负极极片12之间。
加强区13a可用于与负极极片12的容易析锂的位置相对应，这样，当负极极片12析锂时，加强区13a能够有效地分隔正极极片11和负极极片12，降低锂枝晶穿过隔离组件13的风险，提高寿命和安全性。相对于加强区13a，基体区13b可具有较小的厚度，这样可以减少隔离组件13的用量，降低成本，提高电极组件10的能量密度。
在一些实施例中，加强区13a的厚度为2μm-100μm。可选地，加强区13a的厚度为2μm、5μm、7μm、10μm、12μm、20μm、30μm、50μm、80μm或100μm。
加强区13a的厚度越小，电极组件10的能量密度越高，但加强区13a被锂枝晶穿过的风险越高。加强区13a的厚度越大，电极组件10的能量密度越低，但加强区13a被锂枝晶穿过的风险越低，电极组件10的安全性越高。
发明人经过试验和计算，将加强区13a的厚度限制在2μm-100μm，以平衡电极组件10的能量密度和安全性。
在一些实施例中，加强区13a的厚度为5μm-30μm。
在一些实施例中，加强区13a设置为多层结构，基体区13b设置为单层结构。
在加强区13a，多个隔离层层叠在一起以形成多层结构。多个隔离层的层叠方向平行于正极极片11和负极极片12的层叠方向。在加强区13a，相邻的两个隔离层可以相互连接，也可以彼此分离。
对于具有多层结构的加强区13a，加强区13a的厚度指的是多个隔离层的厚度之和。
加强区13a的层数大于或等于2。示例性地，加强区13a的层数可为2-15。
在基体区13b，隔离层为单层。基体区13b可以为一个，也可以为多个。示例性地，基体区13b和加强区13a均为多个，多个基体区13b和多个加强区13a沿卷绕方向W交替设置。
基体区13b用于与负极极片12的不易析锂的位置相对应。基体区13b具有较少的层数，这样可以减少隔离组件13的用量，提高电池单体的能量密度。
当负极极片12的表面析出锂层后，锂层会挤压加强区13a的靠近负极极片12的隔离层，靠近负极极片12的隔离层在锂层的挤压下拉伸。当靠近负极极片12的隔离层局部的微孔的孔径变大并形成缺陷区域时，锂层中较小的锂枝晶可能会穿过缺陷区域。加强区13a的远离负极极片12的隔离层可以将穿过缺陷区域的锂枝晶与正极极片11绝缘隔离，从而降低锂枝晶与正极极片11接触的风险，提供安全性。
加强区13a的远离负极极片12的隔离层与锂层的距离较大，其受到锂层的挤压力较小，其在挤压力的作用下拉伸并产生缺陷区域的风险也较小。隔离层在拉伸过程中产生缺陷区域的位置是不确定的，即使远离负极极片12的隔离层也产生了缺陷区域， 远离负极极片12的隔离层的缺陷区域与靠近负极极片12的隔离层的缺陷区域正好相对的可能性很小，锂枝晶同时穿过加强区13a的难度较大。因此，本申请实施例通过设置加强区13a，可以有效地降低短路风险，提高安全性。
在厚度相同的前提下，相较于具有单层结构的加强区13a，具有多层结构的加强区13a能够更有效地阻挡锂枝晶，降低短路风险，提高安全性。示例性地，由两层5μm的隔离层构成的加强区13a的防护效果优于由10μm的单层隔离层构成的加强区13a的防护效果。换言之，在满足绝缘要求的前提下，相较于具有单层结构的加强区13a，具有多层结构的加强区13a可以采用较小的厚度，这样可以减少隔离组件13的用量，提高电极组件10的能量密度。
在一些实施例中，正极极片11、隔离组件13和负极极片12经过卷绕形成弯折区域B，加强区13a的至少部分设置于弯折区域B。
卷绕方向W为正极极片11、负极极片12和隔离组件13从内向外周向卷绕的方向。示例性地，在图中，卷绕方向W为逆时针方向。
弯折区域B为电极组件10中具有弯折结构的区域，在该弯折区域B，正极极片11、负极极片12和隔离组件13均弯折。示例性地，正极极片11的位于弯折区域B的部分大体弯折为圆弧形，负极极片12的位于弯折区域B的部分大体弯折为圆弧形。
卷绕设备将正极极片11、负极极片12以及隔离组件13卷绕成若干圈，每一圈可以构造有几层，一圈指的是电极组件10上的某个点作为起始端开始计算，沿着卷绕方向W一周到达另一个点定位结束端，结束端与起始端以及此圈的中心在一条直线上，起始端在结束端与此圈中心之间。
电极组件10可以整体为弯折区域B，也可以仅部分区域为弯折区域B。示例性地，电解组件包括平直区域A和弯折区域B，弯折区域B连接于平直区域A，平直区域A为电极组件10的具有平直结构的区域。
加强区13a的可以整体设置于弯折区域B，也可以仅部分设置于弯折区域B。
位于弯折区域B的正极极片11和负极极片12需要进行折弯，而正极活性物质层和负极活性物质层容易在折弯过程中产生应力集中并导致各自的活性物质脱落。由于活性物质的脱落，尤其是负极极片12上活性物质的脱落，可能导致该负极极片12的负极活性物质层的嵌锂位少于其相邻的正极极片11的正极活性物质层能够提供的锂离子数量，从而引发析锂现象。本申请实施例将加强区13a的至少部分设置于弯折区域B，即使弯折区域B出现了析锂的情况，加强区13a也能够阻挡锂枝晶，减小正极极片11和负极极片12导通的概率，有效地降低短路风险，提高电极组件10的使用寿命和安全性。
在一些实施例中，正极极片11包括位于弯折区域B并与加强区13a相邻的第一弯折部111，负极极片12包括与第一弯折部111相邻的第二弯折部121。加强区13a包括多个弯折层14，多个弯折层14位于弯折区域B并层叠于第一弯折部111和第二弯折部121之间。
第一弯折部111和第二弯折部121相邻是指它们之间没有包括另一层正极极片或另一层负极极片。加强区13a与第一弯折部111相邻是指它们之间没有另一层正极极 片或另一层负极极片。
正极极片11包括位于弯折区域B的多个正极弯折部11a，与具有多层结构的加强区13a相邻的正极弯折部11a为第一弯折部111。在正极极片11中，可以是部分地正极弯折部11a为第一弯折部111，也可以是全部的正极弯折部11a均为第一弯折部111。
负极极片12包括位于弯折区域B的多个负极弯折部，示例性地，与第一弯折部111相邻并与第一弯折部111夹持加强区13a的负极弯折部为第二弯折部121。
在电极组件10中，可以仅在第一弯折部111的内侧设置加强区13a和第二弯折部121，也可以仅在第一弯折部111的外侧设置加强区13a和第二弯折部121，也可以在第一弯折部111的两侧均设置加强区13a和第二弯折部121。
多个弯折层14可以在第二弯折部121析锂时阻挡锂枝晶，降低锂枝晶与第一弯折部111接触的风险，提高安全性。
在一些实施例中，第一弯折部111的至少内侧设有加强区13a和第二弯折部121。
位于第一弯折部111内侧的第二弯折部121的曲率大于第一弯折部111的曲率，所以第二弯折部121在弯折的过程中更容易出现活性物质的脱落，也就是说，第一弯折部111内侧的第二弯折部121更容易出现析锂。加强区13a能够将第一弯折部111和位于第一弯折部111内侧的第二弯折部121隔开，即使第二弯折部121析锂，也能够减小锂枝晶穿过加强区13a的概率，降低短路风险，提高安全性。
在一些实施例中，第一弯折部111包括第一集流部1111和设置于第一集流部1111表面的第一活性物质层1112，第一活性物质层1112的厚度为h1。第二弯折部121包括第二集流部1211和设置于第二集流部1211表面的第二活性物质层1212，第二活性物质层1212的厚度为h2，弯折层14的厚度为h3，第二集流部1211的厚度为h4。在第一弯折部111的厚度方向上，第一弯折部111和第二弯折部121之间的最大间距为X。位于第一弯折部111和第二弯折部121之间的弯折层14的层数为Y，Y为大于1的正整数。第一活性物质层1112的单位面积活性物质容量为A1，第二活性物质层1212的单位面积活性物质容量为A2。
第一集流部1111可为正极集流体的一部分，第一活性物质层1112为正极活性物质层的一部分。第二集流部1211可为负极集流体的一部分，第二活性物质层1212为负极活性物质层的一部分。
在第一弯折部111的厚度方向上，第一弯折部111的面向第二弯折部121的表面与第二弯折部121的面向第一弯折部111的表面的最大间距为X。示例性地，第一弯折部111的厚度方向可为第一弯折部111的面向第二弯折部121的表面的法线方向。
第一活性物质层1112的单位面积活性物质容量A1即为：第一活性物质层1112的活性物质容量与第一集流部1111的涂覆有第一活性物质层1112的表面的面积之比。第二活性物质层1212的单位面积活性物质容量A2即为：第二活性物质层1212的活性物质容量与第二集流部1211的涂覆有第二活性物质层1212的表面的面积之比。
第一活性物质层1112的平均放电容量测试。取上述各实施例的正极极片11， 利用冲片模具获得含单面第一活性物质层1112的小圆片。以金属锂片为对电极，Celgard膜为隔离膜，溶解有LiPF 6(1mol/L)的EC+DMC+DEC(体积比为1:1:1的碳酸乙烯酯、碳酸二甲酯、碳酸二乙酯)的溶液为电解液，在氩气保护的手套箱中组装6个相同的CR2430型扣式电池单体。①电池单体组装完后静置12h，②在0.1C的充电电流下进行恒流充电，直到电压到达上限截止电压x 1V，然后保持电压x 1V进行恒压充电，直到电流为50μA，③静置5min，④最后在0.1C的放电电流下进行恒流放电，直到电压到达下限截止电压y 1V，⑤静置5min,重复步骤②-⑤，记录第2次循环的放电容量。6个扣式电池放电容量的平均值即为单面第一活性物质层1112的平均放电容量，可作为第一活性物质层1112的单位面积活性物质容量A1。例如，当正极活性材料为磷酸铁锂时，上限截止电压x 1V＝3.75V，下限截止电压y 1V＝2V。当正极活性材料为锂镍钴锰氧化物(NCM)时，上限截止电压x 1V＝4.25V，下限截止电压y 1V＝2.8V。
第二活性物质层1212的平均放电容量测试。取上述各实施例的负极极片12，利用冲片模具获得与上述的正极小圆片面积相同且包含单面第二活性物质层1212的小圆片。以金属锂片为对电极，Celgard膜为隔离膜，溶解有LiPF 6(1mol/L)的EC+DMC+DEC(体积比为1:1:1的碳酸乙烯酯、碳酸二甲酯、碳酸二乙酯)的溶液为电解液，在氩气保护的手套箱中组装6个CR2430型扣式电池。①电池组装完后静置12h，②在0.05C的放电电流下进行恒流放电，直到电压到达下限截止电压y 2mV，③然后再用50μA的放电电流进行恒流放电，直到电压达到下限截止电压y 2mV，④静置5min，⑤接着用10μA的放电电流进行恒流放电，直到达到下限截止电压y 2mV，⑥静置5分钟，⑦最后在0.1C的充电电流下进行恒流充电，直到最终电压达到上限截至电压x 2V，⑧静置5分钟，重复步骤②-⑧，记录第2次循环的充电容量。6个扣式电池充电容量的平均值即为单面第二活性物质层1212的平均充电容量，可作为第二活性物质层1212的单位面积活性物质容量A2。例如，当负极活性材料为石墨时，上限截止电压x 2V＝2V，下限截止电压y 2V＝5mV。当负极极活性材料为硅时，上限截止电压x 2V＝2V，下限截止电压y 2V＝5mV。
在一些实施例中，A2/A1≥1。h1、h2、h3、h4、X以及Y满足：
Figure PCTCN2022094258-appb-000003
加强区13a的弯折层14的层数越少，锂枝晶穿过加强区13a的风险越高；加强区13a的弯折层14的层数越多，隔离组件13的结构越复杂，电极组件10的能量密度越低。发明人经过试验和计算，根据上述公式设置弯折层14的层数，以平衡电极组件10的安全性和能量密度。
在一些实施例中，A2/A1＜1。h1、h2、h3、h4、X以及Y满足：
Figure PCTCN2022094258-appb-000004
当A2/A1＜1时，第二活性物质层1212的嵌锂空间不足，第一活性物质层1112脱出的锂离子无法等量的嵌入第二活性物质层1212，无法嵌入第二活性物质层1212的锂离子只能在第二活性物质层1212表面得电子，从而出现析锂现象。相较于A2/A1≥1 的电极组件10，A2/A1＜1的电极组件10析锂现象更严重，加强区13a的弯折层14需要更多的层数。
发明人经过试验和计算，根据上述公式设置弯折层14的层数，以平衡电极组件10的安全性和能量密度。
在一些实施例中，h1的值为5μm-80μm。可选地，h1的值为5μm、10μm、20μm、30μm、50μm或80μm。
在一些实施例中，h2的值为10μm-100μm。可选地，h2的值为10μm、20μm、30μm、50μm、80μm或100μm。
在一些实施例中，h3的值为1μm-20μm。可选地，h3的值为1μm、3μm、5μm、10μm、15μm或20μm。
在满足隔离效果的前提下，h3的值越小，加强区13a的弯折层14的层数越多。如果h3的值过小，那么会造成加强区13a的弯折层14的层数过多，导致隔离组件13的结构复杂，不易成型。鉴于此，发明人将h3的值设置为大于或等于1μm。
h3的值越大，加强区13a的总厚度越大；如果h3的值过大，那么会造成电极组件10的能量密度偏低。鉴于此，发明人将h3的值设置为小于或等于20μm，以保证电极组件10的能量密度。
在一些实施例中，h4的值为2μm-20μm，可选地，h4的值可为2μm、3μm、5μm、10μm、15μm或20μm。
在一些实施例中，X的值为10μm-5000μm。可选地，X的值可为10μm、20μm、50μm、100μm、500μm、1000μm、2000μm或5000μm。
在一些实施例中，正极极片11包括沿卷绕方向W设置的多个正极弯折部11a，至少正极极片11的第一次弯折所形成的正极弯折部11a设置为第一弯折部111。也就是说，正极极片11的第一次弯折所形成的正极弯折部11a与加强区13a相邻设置。
正极极片11的多个正极弯折部11a均弯折设置。示例性地，正极弯折部11a大体为圆弧状。
正极极片11的第一次弯折所形成的正极弯折部11a是指正极极片11在沿卷绕方向W卷绕的过程中第一次弯折所形成的正极弯折部11a。
正极极片11的第一次弯折所形成的正极弯折部11a的曲率较大，在充电时，与正极极片11的第一次弯折所形成的正极弯折部11a相邻的负极极片12更容易出现析锂问题。本实施例将正极极片11的第一次弯折所形成的正极弯折部11a设置为第一弯折部111，以使加强区13a能够有效地将正极极片11的第一次弯折所形成的正极弯折部11a与锂枝晶隔离，降低短路风险，提高安全性。
在一些实施例中，正极极片11的第二次弯折所形成的正极弯折部11a也设置为第一弯折部111。也就是说，正极极片11的第二次弯折所形成的正极弯折部11a也与加强区13a相邻设置。
正极极片11的第二次弯折所形成的正极弯折部11a是指正极极片11在沿卷绕方向W卷绕的过程中第二次弯折所形成的正极弯折部11a。
与正极极片11的第一次弯折所形成的正极弯折部11a相邻的加强区13a可以和 与正极极片11的第二次弯折所形成的正极弯折部11a相邻的加强区13a连为一体，也可以沿卷绕方向W间隔设置。
正极极片11的第二次弯折所形成的正极弯折部11a的曲率较大，在充电时，与正极极片11的第二次弯折所形成的正极弯折部11a相邻的负极极片12容易出现析锂问题。本实施例将正极极片11的第二次弯折所形成的正极弯折部11a设置为第一弯折部111，以使加强区13a能够有效地将正极极片11的第二次弯折所形成的正极弯折部11a与锂枝晶隔离，降低短路风险，提高安全性。
在一些实施例中，位于正极极片11的第一次弯折所形成的正极弯折部11a内侧的加强区13a的总厚度为T1，位于正极极片11的第二次弯折所形成的正极弯折部11a内侧的加强区13a的总厚度为T2，T1≥T2。
位于正极极片11的第一次弯折所形成的正极弯折部11a内侧的第二弯折部121的曲率大于位于正极极片11的第二次弯折所形成的正极弯折部11a内侧的第二弯折部121的曲率，位于正极极片11的第一次弯折所形成的正极弯折部11a内侧的第二弯折部121更容易析锂。本实施例使T1≥T2，以降低正极极片11的第一次弯折所形成的正极弯折部11a与锂枝晶导通的风险，提高电池单体的安全性。
在一些实施例中，位于正极极片11的第一次弯折所形成的正极弯折部11a内侧的加强区13a的隔离层的层数为L1，位于正极极片11的第二次弯折所形成的正极弯折部11a内侧的加强区13a的隔离层的层数为L2，L1≥L2。
在一些实施例中，第一弯折部111的两侧均设置有加强区13a和第二弯折部121，位于第一弯折部111内侧的加强区13a的总厚度大于或等于位于第一弯折部111外侧的加强区13a的总厚度。
第一弯折部111的两侧的加强区13a可以属于同一个隔离组件13，也可以分别属于两个不同的隔离组件13。
位于第一弯折部111的内侧的第二弯折部121的曲率大于位于第一弯折部111的外侧的第二弯折部121的曲率，位于第一弯折部111的内侧的第二弯折部121更容易出现析锂。本实施例使位于第一弯折部111的内侧的加强区13a的厚度不小于位于第一弯折部111外侧的加强区13a的厚度，以降低第一弯折部111与锂枝晶导通的风险，提高电池单体的安全性。
在一些实施例中，位于第一弯折部111内侧的加强区13a的隔离层的层数大于或等于位于第一弯折部111外侧的加强区13a的隔离层的层数。
在一些实施例中，正极极片11、隔离组件13和负极极片12经过卷绕还形成平直区域A，平直区域A连接于弯折区域B。基体区13b的至少部分设置于平直区域A。
平直区域A为电极组件10具有平直结构的区域，正极极片11和负极极片12的位于平直区域A的部分基本平直设置。示例性地，位于平直区域A的每层正极极片11的表面和每层负极极片12的表面均基本为平面。
位于平直区域A的正极极片11和负极极片12均处于平直状态，平直区域A的活性物质的不易脱落，位于平直区域A的负极极片12不易出现析锂问题，因此，即使将基体区13b设置到平直区域A，也能改善正负极片之间的绝缘性，降低短路风险。
在一些实施例中，弯折区域B设置为两个，两个弯折区域B分别设置于平直区域A的两端。
在一些实施例中，加强区13a沿卷绕方向W的两端均位于平直区域A，这样可以使加强区13a整体穿过弯折区域B，从而降低弯折区域B短路的风险。
在一些实施例中，在卷绕方向W上，加强区13a的尾端超出弯折区域B的尺寸为3mm-500mm。可选地，加强区13a的尾端超出弯折区域B的尺寸为10mm-100mm。
在一些实施例中，隔离组件13包括第一隔离层131和第二隔离层132，第一隔离层131用于将正极极片11和负极极片12绝缘隔离，第二隔离层132的至少部分位于正极极片11和负极极片12之间并与第一隔离层131层叠。第一隔离层131的与第二隔离层132重叠的区域以及第二隔离层132形成隔离组件13的加强区13a，第一隔离层131的不与第二隔离层132重叠的区域形成基体区13b。
示例性地，第一隔离层131可以理解为相关技术中的正极极片11和负极极片12之间的一层隔离层，即基础隔离层，第二隔离层132可以理解为额外增加的隔离层，即附加隔离层。
在隔离组件13中，第二隔离层132可以为一个，也可以为多个。
第一隔离层131和第二隔离层132可以是一体式构件的两个部分，也可以是分开提供的两个独立构件。
第一隔离层131和第二隔离层132可以由同种材料制成，也可以由不同材料制成。
本实施例对第一隔离层131的厚度和第二隔离层132的厚度不作限定，第一隔离层131的厚度可以大于、等于或小于第二隔离层132的厚度。
第一隔离层131和第二隔离层132层叠在正极极片11和负极极片12之间。第二隔离层132可以独立地设置于第一隔离层131，即在第一隔离层131和第二隔离层132的层叠方向上，第二隔离层132面向第一隔离层131的表面与第一隔离层131之间无粘附等连接关系。当然，第二隔离层132也可以附接于第一隔离层131的表面，示例性地，第二隔离层132可以整体附接于第一隔离层131，也可以仅部分附接于第一隔离层131。附接指的是贴附连接。
本申请实施例在电极组件10中额外附加第二隔离层132，以在隔离组件13上形成具有较大厚度的加强区13a，从而降低因析锂引发的短路风险，提高安全性。
在一些实施例中，在加强区13a，第二隔离层132的层数为1-10。示例性地，在加强区13a，第二隔离层132的层数为1、2、3、5或10。当一个加强区13a设有多个第二隔离层132时，多个第二隔离层132沿卷绕方向W的尺寸可以相同，也可以不相同。
在一些实施例中，隔离组件13的加强区13a为多个，多个加强区13a的第二隔离层132的层数可以相同，也可以不同。
在一些实施例中，第二隔离层132的厚度小于或者等于第一隔离层131的厚度。
第一隔离层131和第二隔离层132可以起到多层防护的功能，所以增加的第二隔离层132可以具有不大于第一隔离层131的厚度，以减小第二隔离层132的用量。
可选地，第二隔离层132的厚度小于第一隔离层131的厚度。
在一些实施例中，第二隔离层132设置于第一隔离层131的面向正极极片11的一侧。
在一些实施例中，第一隔离层131的厚度为2μm-30μm。可选地，第一隔离层131的厚度为2μm、5μm、7μm、10μm、15μm、20μm或30μm。
在一些实施例中，第二隔离层132的厚度为1μm-25μm。可选地，第二隔离层132的厚度为1μm、2μm、5μm、7μm、10μm、15μm、20μm或25μm。
在一些实施例中，第二隔离层132的孔隙率小于第一隔离层131的孔隙率。由于第二隔离层132具有较小的孔隙率，所以当锂枝晶穿过第一隔离层131后，锂枝晶不易从第二隔离层132中的微孔中穿过，从而降低锂枝晶与正极极片11导通的风险，提高安全性。
在一些实施例中，第二隔离层132为多孔结构，第二隔离层132中的孔的孔径小于或等于1μm。
第二隔离层132中的孔的孔径较小，锂枝晶不易穿过，从而降低锂枝晶与正极极片11导通的风险，提高安全性。
在一些实施例中，第一隔离层131包括基膜133和涂覆于基膜133的表面的绝缘层134。基膜133可为多孔薄膜。示例性地，基膜133由电绝缘且具有保液能量的聚合物材料制成，例如PP(聚丙烯)、PE(聚乙烯)或PVDF(聚偏二氟乙烯)。
绝缘层134为设置于基膜133表面的功能层。示例性地，绝缘层134包括无机材料、聚合物粘接剂和分散剂，无机材料可包括勃母石和二氧化硅中的至少一种，聚合物粘接剂可包括PVDF和聚苯乙烯-丙烯酸酯中的至少一种，分散剂可包括聚乙烯醇。无机材料可以对基膜133进行夹持，减小基膜133的收缩。聚合物粘接剂可以粘接到极片，增大电极组件10的整体刚度。
第二隔离层132可以仅包括基膜133，也可以同时包括基膜133和绝缘层134。可选地，第二隔离层132的基膜133与第一隔离层131的基膜133连为一体。
在本申请实施例中，加强区13a的层数是以基膜133的层数确定的。换言之，加强区13a的层数，指的是加强区13a的基膜133的层数。
在一些实施例中，绝缘层134的厚度为0.5μm-10μm。无机材料的颗粒大小为0.1μm-10μm。绝缘层134中无机材料的含量为70％-98％；聚合物粘接剂的含量为1％-20％：分散剂的含量为0.5％-10％。
在一些实施例中，在第一隔离层131和第二隔离层132的层叠方向上，第二隔离层132的至少部分与第一隔离层131分离设置。
第二隔离层132的至少部分与第一隔离层131之间无粘附等连接关系。
当第一隔离层131(或第二隔离层132)在锂层的挤压下拉伸时，第二隔离层132与第一隔离层131分离的部分受到来自第一隔离层131的影响较小，第二隔离层132拉伸的程度较小，产生缺陷的风险较低。因此，本实施例可以有效地降低锂枝晶穿过第一隔离层131和第二隔离层132的风险，提高安全性。
在一些实施例中，正极极片11、隔离组件13和负极极片12经过卷绕形成弯折 区域B和平直区域A，平直区域A连接于弯折区域B。第二隔离层132的一部分位于弯折区域B，第二隔离层132的另一部分位于平直区域A。在弯折区域B，第二隔离层132与第一隔离层131分离设置；在平直区域A，第二隔离层132附接于第一隔离层131。
弯折区域B析锂的风险较高，将弯折区域B的第二隔离层132与第一隔离层131分离设置，可以有效地降低锂枝晶穿过第一隔离层131和第二隔离层132的风险，提高安全性。在平直区域A，第二隔离层132附接于第一隔离层131，可以减小第二隔离层132沿卷绕方向W的移动幅度，降低第二隔离层132错位的风险。
在一些实施例中，第二隔离层132由第一隔离层131的端部折叠而成。
示例性地，第一隔离层131的端部经过折叠后形成第二隔离层132，折叠处即为第一隔离层131和第二隔离层132的分界处。
本实施例使第二隔离层132直接从第一隔离层131的端部开始延伸，无需单独进行增加和固定第二隔离层132，从而使得卷绕过程更为方便，电极组件10的一体性更好。
在一些实施例中，正极极片11、隔离组件13和负极极片12卷绕设置，电极组件10包括沿卷绕方向W的起始段100，第一隔离层131的端部位于起始段100。
沿卷绕方向W的起始段100指的是电极组件10的位于最内圈的端部。
第二隔离层132可以从起始段100沿卷绕方向W延伸并经过正极极片11第一次弯折所形成的正极弯折部11a，可减小锂枝晶同时穿过第一隔离层131和第二隔离层132并与正极极片11的正极弯折部11a接触的风险，提高安全性。同时，本实施例还可以减小第二隔离层132需要延伸的长度，节省用量，降低成本。
在一些实施例中，正极极片11、隔离组件13和负极极片12经过卷绕形成弯折区域B，弯折区域B包括沿卷绕方向W靠近起始段100的第一弯折部位B1，第一弯折部位B1设置有第一隔离层131和第二隔离层132，第二隔离层132从第一隔离层131的端部延伸并超出第一弯折部位B1。
第一弯折部位B1是电极组件10在卷绕成型过程中第一次弯折的位置。示例性地，在第一弯折部位B1，正极极片11进行第一次弯折，负极极片12进行第一次弯折。
在第一弯折部位B1，正极极片11和负极极片12弯折的曲率最大，在充电时，负极极片12出现析锂的风险最高。第二隔离层132延伸并超出第一弯折部位B1，第一隔离层131和第二隔离层132至少能够保护最容易出现析锂问题的第一弯折部位B1，同时还能够节省第二隔离层132的使用，从而在节约成本的同时，提高电极组件10的安全性和使用寿命。
图9为本申请另一些实施例提供的电极组件的隔离组件在卷绕前的结构示意图。
如图9所示，在一些实施例中，隔离组件13整体为单层结构。隔离组件13在成型时，直接形成具有厚度差异的加强区13a和基体区13b。
图10为本申请又一些实施例提供的电极组件的结构示意图；图11为图10所示的电极组件的局部放大示意图；图12为图10所示的电极组件在卷绕前的结构示意图。
如图10至图12所述，在一些实施例中，加强区13a和基体区13b均设置为多个，多个加强区13a和多个基体区13b沿卷绕方向W交替设置。
多个加强区13a可以分别与正极极片11的多个正极弯折部11a对应，以降低正极极片11的多个正极弯折部11a出现短路风险，提高安全性。
各加强区13a均包括一个或多个第二隔离层132。多个加强区13a的层数可以相同，也可以不同。
在一些实施例中，每个加强区13a可隔离一个正极弯折部11a和负极极片12的一个负极弯折部。
在一些实施例中，正极极片11、隔离组件13和负极极片12经过卷绕形成弯折区域B。弯折区域B包括沿卷绕方向W设置的多个弯折部位，电极组件10包括多个第二隔离层132，第一隔离层131和多个第二隔离层132设置于多个弯折部位中的至少一个。
弯折部位是电极组件10在卷绕成型过程中弯折的位置。示例性地，多个弯折部位包括第一弯折部位B1和第二弯折部位B2，在第一弯折部位B1，正极极片11和负极极片12均进行第一次弯折，在第二弯折部位B2，正极极片11和负极极片12均进行第二次弯折。
在本实施例中，在多个弯折部位中的部分或全部位置设置第二隔离层132，能够有效地降低弯折部位短路的风险，提高安全性。
需要说明的是，可以设置其中一个第二隔离层132延伸经过多个弯折部位，也可以设置每个第二隔离层132延伸经过一个弯折部位。
在一些实施例中，沿卷绕方向W，多个第二隔离层132间隔设置。
多个第二隔离层132间隔设置，可理解为多个第二隔离层132不连接为一整片第二隔离层132，而是分体式的。本实施例可以使得第二隔离层132的设置方式更为灵活，即可以任意将第二隔离层132设置到需要增加隔离层层数的位置，同时也可减少因在不需要增加隔离层层数的位置增加第二隔离层132而造成的浪费，提高能量密度。
在一些实施例中，电极组件10包括沿卷绕方向W的起始段100。多个弯折部位包括第一弯折部位B1和第二弯折部位B2，沿卷绕方向W，第一弯折部位B1比第二弯折部位B2更靠近起始段100。设置在第一弯折部位B1的第二隔离层132的厚度大于设置在第二弯折部位B2的第二隔离层132的厚度。
第一弯折部位B1的负极极片12析锂的风险高于第二弯折部位B2的负极极片12的析锂的风险，锂枝晶穿过第一弯折部位B1的第二隔离层132的风险高于锂枝晶穿过第二弯折部位B2的第二隔离层132的风险，因此，本实施例使设置在第一弯折部位B1的第二隔离层132的厚度大于设置在第二弯折部位B2的第二隔离层132的厚度，以在更容易短路的第一弯折部位B1加强防护，提高安全性，并节省第二隔离层132的用量。
在一些实施例中，多个第二隔离层132粘接于第一隔离层131的表面，可以降低第二隔离层132在电极组件10的充放电过程中发生位置偏移的风险，保证第二隔离层132的隔离效果。
可选地，第二隔离层132沿卷绕方向W的两端粘接于第一隔离层131，第二隔离层132沿卷绕方向W的中部与第一隔离层131分离设置。
在一些实施例中，在电极组件10卷绕成型后，从外部热压电极组件10，以使第二隔离层132粘接于第一隔离层131。
在一些实施例中，第一隔离层131包括沿自身厚度方向的两个表面，多个第二隔离层132位于第一隔离层131的同一表面。
正极极片11和负极极片12之间的间距过大会影响嵌锂的过程，导致析锂现象加重，将多个第二隔离层132设置于第一隔离层131的同一个表面，可以在第一隔离层131张紧时，减小第二隔离层132对正极极片11和负极极片12之间的间距的影响，降低析锂风险，提高安全性。
图13为本申请又一些实施例提供的电极组件在卷绕前的结构示意图。
如图13所示，在一些实施例中，沿卷绕方向W，多个加强区13a的厚度从内到外逐渐减小。
在本实施例中，沿卷绕方向W，最内侧的加强区13a的厚度大于最外侧的加强区13a的厚度。相邻的两个加强区13a的厚度可以相同，也可以不同。
沿卷绕方向W，正极极片11的从内到外的正极弯折部11a的曲率逐渐减小，与锂枝晶接触的风险也逐渐降低。本实施例这可以在短路风险高的区域增大加强区13a的厚度，在短路风险低的区域减小加强区13a的厚度，这样可以提高安全性，并节省隔离组件13的用量。
在一些实施例中，沿卷绕方向W，相邻的加强区13a的厚度差为0.5μm-10μm。可选地，相邻的加强区13a的厚度差为0.5μm、1μm、2μm、5μm、7μm或10μm。
图14为本申请再一些实施例提供的电极组件的结构示意图。
如图14所示，在一些实施例中，正极极片11包括沿卷绕方向W设置的多个正极弯折部11a，至少正极极片11的最后一次弯折所形成的正极弯折部11a设置为第一弯折部111。
电极组件10在充电时膨胀并挤压壳体，壳体会对电极组件10施加反作用力。负极极片12的与正极极片11的最后一次弯折所形成的正极弯折部11a相对的区域在反作用力的作用下容易析锂。本实施例使加强区13a的至少部分与正极极片11的最后一次弯折所形成的正极弯折部11a相邻，以降低正极极片11的最后一次弯折所形成的正极弯折部11a与锂枝晶导通的风险，提高电池单体的安全性。
示例性地，电极组件10为圆柱状。正极极片11的每个正极弯折部11a指的是一圈正极极片。
根据本申请的一些实施例，本申请还提供了一种电池单体，其包括外壳和以上任一实施例的电极组件，电极组件容纳于外壳内。
根据本申请的一些实施例，本申请还提供了一种电池，包括多个以上任一实施例的电池单体。
根据本申请的一些实施例，本申请还提供了一种用电装置，包括以上任一实施例的电池单体，电池单体用于为用电装置提供电能。用电装置可以是前述任一应用电池单体的设备或系统。
根据本申请的一些实施例，参照图4至图8，本申请提供了一种电极组件10， 其包括正极极片11、负极极片12和隔离组件13，隔离组件13用于隔离正极极片11和负极极片12。隔离组件13包括第一隔离层131和第二隔离层132，第一隔离层131用于将正极极片11和负极极片12绝缘隔离，第二隔离层132的至少部分位于正极极片11和负极极片12之间并与第一隔离层131层叠。第一隔离层131的与第二隔离层132重叠的区域以及第二隔离层132形成隔离组件13的加强区13a，第一隔离层131的未与第二隔离层132重叠的区域形成隔离组件13的基体区13b，加强区13a的厚度大于基体区13b的厚度。第二隔离层132由第一隔离层131的端部折叠形成。
正极极片11、隔离组件13和负极极片12经过卷绕形成弯折区域B和平直区域A，平直区域A连接于弯折区域B。加强区13a的至少部分设置于弯折区域B，基体区13b的至少部分设置于平直区域A。
加强区13a的一部分与正极极片11的第一次弯折所形成的正极弯折部11a相邻设置，加强区13a的另一部分与正极极片11的第二次弯折所形成的正极弯折部11a相邻设置。
以下结合实施例进一步说明本申请。
为了使本申请的发明目的、技术方案和有益技术效果更加清晰，以下结合实施例进一步详细描述本申请。但是，应当理解的是，本申请的实施例仅仅是为了解释本申请，并非为了限制本申请，且本申请的实施例并不局限于说明书中给出的实施例。实施例中未注明具体实验条件或操作条件的按常规条件制作，或按材料供应商推荐的条件制作。
实施例1可按照下述步骤制备：
(i)将正极活性物质LiNi 0.8Co 0.1Mn 0.1O 2、导电剂乙炔黑、粘结剂PVDF按质量比96:2:2进行混合，加入溶剂NMP，在真空搅拌机作用下搅拌至体系呈均一状，获得正极浆料；将正极浆料均匀涂覆在铝箔上，室温晾干后转移至烘箱继续干燥，然后经过冷压、分切、裁片得到正极极片。
(ii)将负极活性物质石墨、导电剂乙炔黑、增稠剂CMC、粘结剂SBR按质量比96.4:1:1.2:1.4进行混合，加入溶剂去离子水，在真空搅拌机作用下搅拌至体系呈均一状，获得负极浆料；将负极浆料均匀涂覆在铜箔上，室温晾干后转移至烘箱继续干燥，然后经过冷压、分切、裁片得到负极极片。
(iii)将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)按照按体积比1:1:1进行混合得到有机溶剂，接着将充分干燥的锂盐LiPF6溶解于混合后的有机溶剂中，配制成浓度为1mol/L的电解液。
(iv)将7μm厚的聚乙烯膜作折叠并形成隔离组件，隔离组件包括第一隔离层和第二隔离层，第二隔离层的长度为652.5mm。第一隔离层的与第二隔离层重叠的区域以及第二隔离层形成隔离组件的加强区，第一隔离层的未与第二隔离层重叠的区域形成隔离组件的基体区，加强区的厚度为14μm，基体区的厚度为7μm。
(v)将正极极片、隔离组件及负极极片层叠在一起并卷绕为多圈，卷绕后再压平为扁平状，以制备出电极组件。
(ⅵ)将电极组件装入方形壳体，并焊接壳体和端盖；然后经过注液、静 置、化成、整形等工序，获得电池单体。示例性地，电池单体的容量为60Ah。
在步骤(v)中，人为地将最内一圈的正极极片和最内一圈的负极极片之间的间隙做到200μm，以加速电极组件的析锂。在卷绕成型的电极组件中，最内一圈的正极极片和最内一圈的负极极片之间设有第一隔离层和第二隔离层。
实施例2：
实施例2的电池单体的制备方法参照实施例1，不同之处在于：在步骤(ⅵ)中，人为地将最内两圈的正极极片和最内两圈的负极极片之间的间隙做到200μm，第二隔离层的长度为873.6mm，第二圈正极极片和第二圈负极极片之间也设有第一隔离层和第二隔离层。
对比例1：
对比例1的电池单体的制备方法参照实施例1，不同之处在于：对比例1的隔离组件未折叠，隔离组件是单层结构。
对比例2：
对比例2的电池单体的制备方法参照实施例2，不同之处在于：对比例2的隔离组件未折叠，隔离组件是单层结构。
实施例1、实施例2、对比例1和对比例2各制备80个电池单体，并对各电池单体进行测试。
具体地，在常温环境下，将电池单体以1C倍率充电、以1C倍率放电，在高SOC(例如0.9-1)区间进行循环充放电。
实施例1的40个电池单体进行500个循环后满充，然后静置24小时，检测电池单体电压下降的幅度，并计算出各电池单体的自放电率，然后求平均值。自放电率为压降/时间。实施例1剩余的40个电池单体进行2000个循环，在循环过程中记录电池单体失效的数量，并计算失效率。
实施例2、对比例1、对比例2也按照上述步骤测试。
实施例1-2和对比示例1-2的评估结果示出于表1中。
表1
  自放电率 失效率
实施例1 0.027mV/h 0％
实施例2 0.053mV/h 2.5％
对比例1 0.71mV/h 92.5％
对比例2 0.89mV/h 95％
参照实施例1-2和对比示例1-2，在正极极片和负极极片之间设置加强区，可以在负极极片析锂时，降低短路风险，提高电池单体的使用寿命。
需要说明的是，在不冲突的情况下，本申请中的实施例及实施例中的特征可以相互组合。
最后应说明的是：以上实施例仅用以说明本申请的技术方案，而非对其限制； 尽管参照前述实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换，但这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的精神和范围。

Claims (34)

  1. 一种电极组件，包括正极极片、负极极片和隔离组件，所述隔离组件用于隔离所述正极极片和所述负极极片；
    所述隔离组件包括基体区和连接于所述基体区的加强区，所述加强区的厚度大于所述基体区的厚度；所述加强区的至少部分位于相邻的所述正极极片和所述负极极片之间。
  2. 根据权利要求1所述的电极组件，其中，所述加强区的厚度为2μm-100μm。
  3. 根据权利要求1或2所述的电极组件，其中，所述正极极片、所述隔离组件和所述负极极片经过卷绕形成弯折区域，所述加强区的至少部分设置于所述弯折区域。
  4. 根据权利要求3所述的电极组件，其中，所述正极极片包括位于所述弯折区域并与所述加强区相邻的第一弯折部，所述负极极片包括与所述第一弯折部相邻的第二弯折部；
    所述加强区包括多个弯折层，所述多个弯折层位于所述弯折区域并层叠于所述第一弯折部和所述第二弯折部之间。
  5. 根据权利要求4所述的电极组件，其中，所述第一弯折部的至少内侧设有所述加强区和所述第二弯折部。
  6. 根据权利要求4或5所述的电极组件，其中，所述第一弯折部包括第一集流部和设置于所述第一集流部表面的第一活性物质层，所述第一活性物质层的厚度为h1；
    所述第二弯折部包括第二集流部和设置于所述第二集流部表面的第二活性物质层，所述第二活性物质层的厚度为h2，所述弯折层的厚度为h3，所述第二集流部的厚度为h4；
    在所述第一弯折部的厚度方向上，所述第一弯折部和所述第二弯折部之间的最大间距为X；
    位于所述第一弯折部和所述第二弯折部之间的所述弯折层的层数为Y，Y为大于1的正整数；
    所述第一活性物质层的单位面积活性物质容量为A1，所述第二活性物质层的单位面积活性物质容量为A2，A2/A1≥1；
    h1、h2、h3、h4、X以及Y满足：
    Figure PCTCN2022094258-appb-100001
  7. 根据权利要求4或5所述的电极组件，其中，所述第一弯折部包括第一集流部和设置于所述第一集流部表面的第一活性物质层，所述第一活性物质层的厚度为h1；
    所述第二弯折部包括第二集流部和设置于所述第二集流部表面的第二活性物质层，所述第二活性物质层的厚度为h2，所述弯折层的厚度为h3，所述第二集流部的厚度为h4；
    在所述第一弯折部的厚度方向上，所述第一弯折部和所述第二弯折部之间的最大 间距为X；
    位于所述第一弯折部和所述第二弯折部之间的所述弯折层的层数为Y，Y为大于1的正整数；
    所述第一活性物质层的单位面积活性物质容量为A1，所述第二活性物质层的单位面积活性物质容量为A2，A2/A1＜1；
    h1、h2、h3、h4、X以及Y满足：
    Figure PCTCN2022094258-appb-100002
  8. 根据权利要求6或7所述的电极组件，其中，h3的值为1μm-20μm。
  9. 根据权利要求6-8任一项所述的电极组件，其中，X的值为10μm-5000μm。
  10. 根据权利要求4-9任一项所述的电极组件，其中，所述正极极片包括沿卷绕方向设置的多个正极弯折部，至少所述正极极片的第一次弯折所形成的所述正极弯折部设置为所述第一弯折部。
  11. 根据权利要求10所述的电极组件，其中，所述正极极片的第二次弯折所形成的所述正极弯折部也设置为所述第一弯折部。
  12. 根据权利要求11所述的电极组件，其中，位于所述正极极片的第一次弯折所形成的所述正极弯折部内侧的所述加强区的总厚度为T1，位于所述正极极片的第二次弯折所形成的所述正极弯折部内侧的所述加强区的总厚度为T2，T1≥T2。
  13. 根据权利要求4-12任一项所述的电极组件，其中，所述第一弯折部的两侧均设置有所述加强区和所述第二弯折部，位于所述第一弯折部内侧的所述加强区的总厚度大于或等于位于所述第一弯折部外侧的所述加强区的总厚度。
  14. 根据权利要求4-12任一项所述的电极组件，其中，所述正极极片包括沿卷绕方向设置的多个正极弯折部，至少所述正极极片的最后一次弯折所形成的所述正极弯折部设置为所述第一弯折部。
  15. 根据权利要求3-13任一项所述的电极组件，其中，所述正极极片、所述隔离组件和所述负极极片经过卷绕还形成平直区域，所述平直区域连接于所述弯折区域；
    所述基体区的至少部分设置于所述平直区域。
  16. 根据权利要求15所述的电极组件，其中，所述加强区和所述基体区均设置为多个，多个所述加强区和多个所述基体区沿卷绕方向交替设置。
  17. 根据权利要求16所述的电极组件，其中，沿所述卷绕方向，多个所述加强区的厚度从内到外逐渐减小。
  18. 根据权利要求17所述的电极组件，其中，沿所述卷绕方向，相邻的所述加强区的厚度差为0.5μm-10μm。
  19. 根据权利要求1-18任一项所述的电极组件，其中，所述加强区设置为多层结构，所述基体区设置为单层结构。
  20. 根据权利要求1-19任一项所述的电极组件，其中，所述隔离组件包括第一隔离层和第二隔离层，所述第一隔离层用于将所述正极极片和所述负极极片绝缘隔离，所 述第二隔离层的至少部分位于所述正极极片和所述负极极片之间并与所述第一隔离层层叠；
    所述第一隔离层的与所述第二隔离层重叠的区域以及所述第二隔离层形成所述隔离组件的所述加强区，所述第一隔离层的不与所述第二隔离层重叠的区域形成所述基体区。
  21. 根据权利要求20所述的电极组件，其中，所述第二隔离层的厚度小于或者等于所述第一隔离层的厚度。
  22. 根据权利要求20或21所述的电极组件，其中，在所述第一隔离层和所述第二隔离层的层叠方向上，所述第二隔离层的至少部分与所述第一隔离层分离设置。
  23. 根据权利要求22所述的电极组件，其中，所述正极极片、所述隔离组件和所述负极极片经过卷绕形成弯折区域和平直区域，所述平直区域连接于所述弯折区域；
    所述第二隔离层的一部分位于弯折区域，所述第二隔离层的另一部分位于平直区域；
    在所述弯折区域，所述第二隔离层与所述第一隔离层分离设置；在所述平直区域，所述第二隔离层附接于所述第一隔离层。
  24. 根据权利要求20-23任一项所述的电极组件，其中，所述第二隔离层由所述第一隔离层的端部折叠而成。
  25. 根据权利要求24所述的电极组件，其中，所述正极极片、所述隔离组件和所述负极极片卷绕设置，所述电极组件包括沿卷绕方向的起始段，所述第一隔离层的端部位于所述起始段。
  26. 根据权利要求25所述的电极组件，其中，所述正极极片、所述隔离组件和所述负极极片经过卷绕形成弯折区域，所述弯折区域包括沿所述卷绕方向靠近所述起始段的第一弯折部位，所述第一弯折部位设置有所述第一隔离层和所述第二隔离层，所述第二隔离层从所述第一隔离层的端部延伸并超出所述第一弯折部位。
  27. 根据权利要求20-23任一项所述的电极组件，其中，所述正极极片、所述隔离组件和所述负极极片经过卷绕形成弯折区域；
    所述弯折区域包括沿卷绕方向设置的多个弯折部位，所述电极组件包括多个所述第二隔离层，所述第一隔离层和多个所述第二隔离层设置于所述多个弯折部位中的至少一个。
  28. 根据权利要求27所述的电极组件，其中，沿所述卷绕方向，所述多个第二隔离层间隔设置。
  29. 根据权利要求27或28所述的电极组件，其中，所述电极组件包括沿卷绕方向的起始段；所述多个弯折部位包括第一弯折部位和第二弯折部位，沿所述卷绕方向，所述第一弯折部位比所述第二弯折部位更靠近所述起始段；
    设置在所述第一弯折部位的所述第二隔离层的厚度大于设置在所述第二弯折部位的所述第二隔离层的厚度。
  30. 根据权利要求27-39任一项所述的电极组件，其中，所述第一隔离层包括沿自身厚度方向的两个表面，多个所述第二隔离层位于所述第一隔离层的同一表面。
  31. 根据权利要求27-30任一项所述的电极组件，其中，多个所述第二隔离层粘接于所述第一隔离层的表面。
  32. 一种电池单体，包括外壳和根据权利要求1-31任一项所述的电极组件，所述电极组件容纳于所述外壳内。
  33. 一种电池，包括多个根据权利要求32所述的电池单体。
  34. 一种用电装置，包括根据权利要求32所述的电池单体，所述电池单体用于提供电能。
PCT/CN2022/094258 2021-09-10 2022-05-20 电极组件、电池单体、电池以及用电装置 WO2023035669A1 (zh)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1805205A (zh) * 2005-01-14 2006-07-19 比亚迪股份有限公司 锂离子电池的电极片芯及含有该电极片芯的锂离子电池
CN1838451A (zh) * 2005-03-23 2006-09-27 三星Sdi株式会社 电极组件以及利用该组件的锂离子二次电池
JP2015153454A (ja) * 2014-02-10 2015-08-24 トヨタ自動車株式会社 非水電解質二次電池
CN209389153U (zh) * 2019-03-20 2019-09-13 三星(天津)电池有限公司 一种卷绕结构的锂离子电池
CN214254496U (zh) * 2021-01-19 2021-09-21 宁德时代新能源科技股份有限公司 电极组件、电池单体、电池以及用电装置
CN216773319U (zh) * 2022-01-27 2022-06-17 宁波容百新能源科技股份有限公司 一种裸电芯及锂电池

Family Cites Families (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1237650C (zh) * 1997-11-19 2006-01-18 三菱电机株式会社 锂离子二次电池和其制造方法
JP2001229970A (ja) * 2000-02-16 2001-08-24 Shin Kobe Electric Mach Co Ltd 円筒形リチウムイオン電池
CN2798320Y (zh) * 2005-04-18 2006-07-19 比亚迪股份有限公司 碱性二次电池的电极芯及含有该电极芯的碱性二次电池
JP5147206B2 (ja) * 2006-08-11 2013-02-20 三洋電機株式会社 非水電解質二次電池
JP5274059B2 (ja) * 2008-03-13 2013-08-28 日立ビークルエナジー株式会社 捲回式電池の製造方法
JP2011008929A (ja) * 2009-06-23 2011-01-13 Panasonic Corp 非水系二次電池用電極群およびこれを用いた非水系二次電池
CN102487150B (zh) * 2010-12-03 2014-10-08 比亚迪股份有限公司 电池电芯的卷绕方法及装置
JP6095961B2 (ja) * 2011-12-06 2017-03-15 株式会社半導体エネルギー研究所 角形リチウム二次電池
JP6139072B2 (ja) * 2012-07-31 2017-05-31 太陽誘電株式会社 電気化学デバイス及びその製造方法
JP6094807B2 (ja) * 2013-04-26 2017-03-15 株式会社Ｇｓユアサ 渦巻状電極群を備える電池
CN205992575U (zh) * 2016-07-21 2017-03-01 中航锂电（洛阳）有限公司 正极片和卷绕式锂离子动力电池电芯及锂离子动力电池
CN106129483B (zh) * 2016-08-23 2019-04-19 宁德新能源科技有限公司 一种卷绕式电芯
JP6183526B2 (ja) * 2016-09-23 2017-08-23 株式会社Ｇｓユアサ 蓄電素子
WO2018061971A1 (ja) * 2016-09-30 2018-04-05 ブラザー工業株式会社 電池
CN206379432U (zh) * 2016-12-27 2017-08-04 宁德时代新能源科技股份有限公司 二次电池卷绕式电芯
JP6510573B2 (ja) * 2017-02-10 2019-05-08 太陽誘電株式会社 蓄電素子
US20190386344A1 (en) * 2017-02-24 2019-12-19 Sanyo Electric Co., Ltd. Nonaqueous electrolyte secondary battery
CN109802164B (zh) * 2017-11-17 2021-10-01 青海时代新能源科技有限公司 卷绕式电极组件制造装置
CN207572477U (zh) * 2017-12-12 2018-07-03 宁德时代新能源科技股份有限公司 电极组件和二次电池
US20200036034A1 (en) * 2018-07-24 2020-01-30 Michael Wang High-capacity polymer lithium-ion battery structure
CN110364769A (zh) * 2019-07-31 2019-10-22 瑞浦能源有限公司 一种卷绕电芯及电池
CN212810367U (zh) * 2020-08-21 2021-03-26 宁德时代新能源科技股份有限公司 电极组件、电池单体、电池和用电装置
BR112022017318A2 (pt) * 2020-08-21 2023-03-07 Contemporary Amperex Technology Co Ltd Conjunto de eletrodos, célula de bateria, bateria e aparelho elétrico
CN112467231B (zh) * 2021-02-04 2021-09-14 江苏时代新能源科技有限公司 电极组件、电池单体、电池及电极组件的制造方法和设备
CN214706007U (zh) * 2021-03-25 2021-11-12 瑞浦能源有限公司 卷绕电芯及电池
CN112803081B (zh) * 2021-04-14 2021-08-06 江苏时代新能源科技有限公司 一种电池单体及其制备方法、电池及用电装置

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1805205A (zh) * 2005-01-14 2006-07-19 比亚迪股份有限公司 锂离子电池的电极片芯及含有该电极片芯的锂离子电池
CN1838451A (zh) * 2005-03-23 2006-09-27 三星Sdi株式会社 电极组件以及利用该组件的锂离子二次电池
JP2015153454A (ja) * 2014-02-10 2015-08-24 トヨタ自動車株式会社 非水電解質二次電池
CN209389153U (zh) * 2019-03-20 2019-09-13 三星(天津)电池有限公司 一种卷绕结构的锂离子电池
CN214254496U (zh) * 2021-01-19 2021-09-21 宁德时代新能源科技股份有限公司 电极组件、电池单体、电池以及用电装置
CN216773319U (zh) * 2022-01-27 2022-06-17 宁波容百新能源科技股份有限公司 一种裸电芯及锂电池

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