WO2024098354A1 - 电极组件及其制备方法、二次电池和用电装置 - Google Patents

电极组件及其制备方法、二次电池和用电装置 Download PDF

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WO2024098354A1
WO2024098354A1 PCT/CN2022/131251 CN2022131251W WO2024098354A1 WO 2024098354 A1 WO2024098354 A1 WO 2024098354A1 CN 2022131251 W CN2022131251 W CN 2022131251W WO 2024098354 A1 WO2024098354 A1 WO 2024098354A1
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Prior art keywords
segment
contour line
diaphragm
pole piece
electrode assembly
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PCT/CN2022/131251
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English (en)
French (fr)
Inventor
邓亚茜
陈宁
史东洋
程志鹏
王羽臻
金海族
李白清
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2022/131251 priority Critical patent/WO2024098354A1/zh
Publication of WO2024098354A1 publication Critical patent/WO2024098354A1/zh

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    • 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 in particular to an electrode assembly and a preparation method thereof, a secondary battery and an electrical device.
  • the pole pieces in the electrode assembly usually expand, especially on the negative pole piece, which causes the gap between the edge of the pole piece along its width direction and the diaphragm to increase, deteriorating the dynamics, and easily causing lithium precipitation problems, affecting the performance of the secondary battery.
  • the present application provides an electrode assembly, comprising: a plurality of pole pieces, stacked in sequence; a diaphragm, disposed between each two adjacent pole pieces; a reserved gap is formed between the diaphragm and at least one pole piece between two adjacent pole pieces, and the spacing of the reserved gap is denoted as D; in a preset direction of the pole piece, the spacing D tends to increase from any edge of the diaphragm to the middle of the diaphragm, wherein, when the electrode assembly is a winding structure, the preset direction is the width direction of the pole piece; when the electrode assembly is a stacked structure, the preset direction is the width direction or length direction of the pole piece.
  • the above-mentioned electrode assembly forms a reserved space between at least one surface of the diaphragm and the corresponding pole piece, and the spacing D of the reserved space tends to increase from any edge of the diaphragm to the middle of the diaphragm along the preset direction of the pole piece, so that the reserved space has a structure with a large middle and small ends. In this way, during the cyclic charge and discharge process, when the middle part of the pole piece along its own width direction expands more than the two edges, it will be better accommodated in the reserved space.
  • the pole piece can maintain good contact with the diaphragm, avoiding the middle part of the pole piece from contacting the diaphragm due to the large expansion, resulting in an increase in the gap between the edge of the diaphragm and the pole piece, improving the insertion and extraction dynamics at the edge of the pole piece, reducing the occurrence of lithium precipitation, and thus improving the performance of the secondary battery.
  • a surface of the diaphragm facing the reserved gap is defined as a mating surface, and the middle area of the mating surface in the preset direction is recessed along the side away from the corresponding pole piece.
  • the recessed design of the mating surface of the diaphragm forms an effective reserved gap between the diaphragm and the pole piece, reducing the problem of lithium deposition; at the same time, the thick design at both ends can suppress the edge of the pole piece to avoid the problem of wrinkling of the pole piece.
  • the mating surface in a preset direction, includes a first plane segment and two first curved surface segments connected to both sides of the first plane segment; from the side of the first curved surface segment close to the first plane segment to the side of the first curved surface segment away from the first plane segment, the first curved surface segment is arranged along an arc-shaped depression toward the corresponding pole piece.
  • the mating surface is designed as a first plane segment and two first curved surface segments, so that a reserved gap of an arc-shaped depression structure is formed between the mating surface and the pole piece, thereby ensuring that the edge of the pole piece is in better contact with the diaphragm after expansion, reducing the problem of the end of the electrode assembly being fluffy, and improving the dynamics of disengagement.
  • the projection of the first curved surface segment in the plane formed by the thickness direction of the pole piece and the preset direction is a first contour line
  • the coordinate axis is constructed with the end of the first contour line close to the first plane segment as the origin, the direction parallel to the preset direction as the X axis, and the direction parallel to the thickness direction of the pole piece as the Y axis;
  • the curve relationship of the first curved surface segment is satisfied as the function expression of F (X), so that the edge of the expanded pole piece can better contact with the diaphragm, reduce the gap at the edge, improve the insertion and extraction dynamics, reduce the lithium precipitation problem, and improve the performance of the secondary battery.
  • the overall width of the mating surface is recorded as L1
  • the width of the first curved surface segment is recorded as M1
  • the condition satisfied by M1 and L1 is: 1/6 ⁇ M1/L1 ⁇ 1/2.
  • M1/L1 is designed between 1/6 and 1/2, and the curvature of the first curved surface segment is reasonably optimized, so that the edge of the diaphragm can better contact the edge of the expanded electrode, effectively improving the lithium deposition problem.
  • the diaphragm includes a substrate and coatings disposed on two opposite sides of the substrate, and a reserved gap is formed between at least one coating and the corresponding pole piece. In this way, the reserved gap between the coating and the pole piece is used to ensure that the edge of the diaphragm can better contact the expanded pole piece, reduce the gap between the two, and ensure the disengagement dynamics.
  • the thickness of the coating is recorded as h1, and in a preset direction, the thickness h1 increases from the middle of the coating to any edge of the coating. In this way, the coating is applied with uneven thickness, so that the surface of the coating is concave, which is conducive to filling the gap between the edge of the pole piece and the diaphragm.
  • one of the two adjacent electrode sheets is a negative electrode sheet, and a reserved gap is formed between the separator and the negative electrode sheet.
  • a reserved gap is set between the separator and the negative electrode sheet, so that the gap between the edge of the expanded negative electrode sheet and the separator is reduced, the dynamics are improved, and the lithium precipitation problem is improved.
  • a surface on the pole piece used to form a reserved gap is defined as an optimized surface, and the middle area of the optimized surface in a preset direction is recessed along the side away from the corresponding diaphragm.
  • the optimized surface of the pole piece is recessed to form an effective reserved gap between the diaphragm and the pole piece, reducing the problem of lithium deposition; at the same time, the edge of the pole piece can be suppressed by the thick design at both ends to avoid the problem of wrinkling of the pole piece.
  • the optimized surface in a preset direction, includes a second plane segment and two second curved surface segments connected to both sides of the second plane segment, and from the side of the second curved surface segment close to the second plane segment to the side of the second curved surface segment away from the second plane segment, the second curved surface segment is arranged along the arc-shaped depression away from the corresponding diaphragm.
  • the optimized surface is designed as a second plane segment and two second curved surface segments, so that a reserved gap of an arc-shaped depression structure is formed between the optimized surface and the diaphragm, thereby ensuring better contact between the edge of the pole piece and the diaphragm after expansion, reducing the problem of fluffy ends of the electrode assembly, and improving the disengagement dynamics.
  • the projection of the second curved surface segment in the plane formed by the thickness direction of the pole piece and the preset direction is a second contour line
  • the coordinate axis is constructed with the end of the second contour line close to the second plane segment as the origin, the direction parallel to the preset direction as the X axis, and the direction parallel to the thickness direction of the pole piece as the Y axis;
  • the curve relationship of the second curved surface segment is satisfied as the function expression of F (X), so that the edge of the expanded pole piece can better contact with the diaphragm, reduce the gap at the edge, improve the insertion and extraction dynamics, reduce the lithium precipitation problem, and improve the performance of the secondary battery.
  • the overall width of the optimized surface is recorded as L2
  • the width of the second curved surface segment is recorded as M1
  • the condition satisfied by M1 and L is: 1/6 ⁇ M1/L2 ⁇ 1/2.
  • M1/L2 is designed between 1/6 and 1/2, and the curvature of the second curved surface segment is reasonably optimized, so that the edge of the diaphragm can better contact the edge of the expanded electrode, effectively improving the lithium deposition problem.
  • the pole piece includes a current collector and an active layer disposed on two opposite sides of the current collector, and a reserved gap is formed between at least one active layer and the corresponding diaphragm.
  • the reserved gap between the active layer and the diaphragm is used to ensure that the edge of the diaphragm can better contact the expanded pole piece, reduce the gap between the two, and ensure the disengagement dynamics.
  • the thickness of the active layer is recorded as h2, and in a preset direction, the thickness h2 increases from the middle of the active layer to any edge of the active layer. In this way, the surface of the active layer is concave by coating the active layer with uneven thickness, which is conducive to filling the gap between the edge of the pole piece and the diaphragm.
  • the present application provides a secondary battery comprising any one of the above electrode assemblies.
  • the present application provides an electrical device, comprising the above secondary battery.
  • the present application provides a method for preparing an electrode assembly, which is used to prepare any of the above electrode assemblies, comprising the following steps: using a first mold to coat an active layer on a current collector to obtain a pole piece; using a second mold to coat a coating on a substrate to obtain a diaphragm, wherein the coating surface of the first mold and/or the second mold is provided with an arc-shaped protrusion in the middle part in the width direction of the coating surface; stacking the pole piece and the diaphragm and performing lamination or winding operations.
  • the coating surface of the first mold and/or the second mold in the width direction of the coating surface, includes a third plane segment and two third curved surface segments connected to both sides of the third plane segment.
  • the projection of the third curved surface segment in a plane perpendicular to the coating direction of the coating surface is a third contour line.
  • the coordinate axis is constructed with one end of the third contour line close to the third plane segment as the origin, the direction parallel to the width direction of the coating surface as the X axis, and the direction perpendicular to the width direction of the coating surface as the Y axis.
  • FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application.
  • FIG2 is a schematic diagram of an exploded structure of a secondary battery provided in some embodiments of the present application.
  • FIG3 is a schematic diagram of the matching structure of the uneven diaphragm and the pole piece provided in some embodiments of the present application;
  • FIG4 is a schematic diagram of the structure in FIG3 after expansion
  • FIG5 is a schematic cross-sectional view of the coating structure in FIG3 ;
  • FIG6 is a schematic diagram of the cooperation structure of the uneven pole piece and the diaphragm provided in some embodiments of the present application.
  • FIG7 is a schematic cross-sectional view of the active layer structure in FIG6 ;
  • FIG8 is a schematic diagram of a preparation process of an electrode assembly provided in some embodiments of the present application.
  • FIG9 is a schematic diagram of coating a first mold or a second mold provided in some embodiments of the present application.
  • FIG. 10 is a schematic cross-sectional view of a coating surface structure provided in some embodiments of the present application.
  • the term "and/or" is only a description of the association relationship of associated objects, indicating that three relationships may exist.
  • a and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone.
  • the character "/" in this article generally indicates that the associated objects before and after are in an "or" relationship.
  • multiple refers to more than two (including two).
  • multiple groups refers to more than two groups (including two groups), and “multiple pieces” refers to more than two pieces (including two pieces).
  • the thickness of the side reaction accumulation of the battery system and the peeling of the graphite sheet cause the secondary battery to swell, that is, the positive and negative electrodes expand outward.
  • the expansion of the middle part is greater than that of the edge part, forming an arched convexity, which contacts and squeezes the diaphragm, resulting in an increase in the gap between the edge of the diaphragm and the edge of the electrode sheet.
  • the electrolyte will not be able to effectively infiltrate the edge of the electrode, resulting in the inability of lithium ions to be effectively transferred at the edge of the electrode, worsening the insertion and extraction kinetics, and further causing lithium deposition problems at the edge of the electrode.
  • the applicant has designed an electrode assembly after in-depth research.
  • a reserved gap is formed between two adjacent pole pieces and between the diaphragm and at least one pole piece.
  • the spacing of the reserved gap is recorded as D; in the preset direction of the pole piece, the spacing D tends to increase from any edge of the diaphragm to the middle of the diaphragm.
  • a reserved space is formed between at least one surface of the diaphragm and the corresponding pole piece, and the spacing D of the reserved space increases from any edge of the diaphragm to the middle of the diaphragm along the preset direction of the pole piece, so that the reserved space has a structure of being large in the middle and small at both ends.
  • the middle part of the pole piece along its own width direction expands more than the two edges, it will be better accommodated in the reserved space.
  • Such a design ensures that the electrode can maintain good contact with the diaphragm even after expansion, avoiding the middle part of the electrode from coming into contact with the diaphragm due to the large expansion, thereby increasing the gap between the edge of the diaphragm and the electrode, improving the insertion and extraction dynamics at the edge of the electrode, reducing the occurrence of lithium plating, and thus improving the performance of the secondary battery.
  • the secondary battery disclosed in the embodiment of the present application can be used in, but not limited to, electrical devices such as vehicles, ships, or aircraft.
  • a power supply system having the secondary battery disclosed in the present application and the like can be used to form the electrical device.
  • the embodiment of the present application provides an electric device using a secondary battery as a power source
  • the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc.
  • the electric toy may include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, an electric airplane toy, etc.
  • the spacecraft may include an airplane, a rocket, a space shuttle, a spacecraft, etc.
  • FIG. 1 is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of the present application.
  • the vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc.
  • a secondary battery 100 is provided inside the vehicle 1000, and the secondary battery 100 may be provided at the bottom, head or tail of the vehicle 1000.
  • the secondary battery 100 may be used to power the vehicle 1000, for example, the secondary battery 100 may be used as an operating power source for the vehicle 1000.
  • the vehicle 1000 may also include a controller 110 and a motor 120, and the controller 110 is used to control the secondary battery 100 to power the motor 120, for example, for the starting, navigation and working power requirements of the vehicle 1000 during driving.
  • the secondary battery 100 can be used not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.
  • the multiple secondary batteries 100 may be connected in series, in parallel, or in mixed connection.
  • Mixed connection means that the multiple secondary batteries 100 are both connected in series and in parallel.
  • the multiple secondary batteries 100 may be directly connected in series, in parallel, or in mixed connection, and then the whole formed by the multiple secondary batteries 100 is accommodated in a box; of course, the battery may also be a battery module formed by connecting multiple secondary batteries 100 in series, in parallel, or in mixed connection, and then the multiple battery modules are connected in series, in parallel, or in mixed connection to form a whole, and accommodated in a box.
  • the battery may also include other structures, for example, the battery may also include a busbar component for realizing electrical connection between the multiple secondary batteries 100.
  • Each secondary battery 100 may be a lithium sulfur battery, a sodium ion battery or a magnesium ion battery, but is not limited thereto.
  • the secondary battery 100 may be cylindrical, flat, rectangular or in other shapes.
  • FIG. 2 is a schematic diagram of the exploded structure of a secondary battery 100 provided in some embodiments of the present application.
  • the secondary battery 100 refers to the smallest unit of a battery. As shown in FIG. 2, the secondary battery 100 includes an end cap 20, a housing 30, an electrode assembly 10, and other functional components.
  • the end cap 20 refers to a component that covers the opening of the shell 30 to isolate the internal environment of the secondary battery 100 from the external environment.
  • the shape of the end cap 20 can be adapted to the shape of the shell 30 to match the shell 30.
  • the end cap 20 can be made of a material with a certain hardness and strength (such as an aluminum alloy), so that the end cap 20 is not easily deformed when it is squeezed and collided, so that the secondary battery 100 can have a higher structural strength and the safety performance can also be improved.
  • Functional components such as electrode terminals 201 can be provided on the end cap 20. The electrode terminal 201 can be used to electrically connect to the electrode assembly 10 for outputting or inputting electrical energy of the secondary battery 100.
  • the end cap 20 can also be provided with a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the secondary battery 100 reaches a threshold.
  • the material of the end cap 20 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.
  • an insulating member may be provided inside the end cap 20, and the insulating member may be used to isolate the electrical connection components in the housing 30 from the end cap 20 to reduce the risk of short circuit.
  • the insulating member may be plastic, rubber, or the like.
  • the shell 30 is a component used to cooperate with the end cap 20 to form the internal environment of the secondary battery 100, wherein the formed internal environment can be used to accommodate the electrode assembly 10, the electrolyte and other components.
  • the shell 30 and the end cap 20 can be independent components, and an opening can be set on the shell 30, and the internal environment of the secondary battery 100 is formed by covering the opening with the end cap 20 at the opening.
  • the end cap 20 and the shell 30 can also be integrated.
  • the end cap 20 and the shell 30 can form a common connection surface before other components are put into the shell, and when the interior of the shell 30 needs to be encapsulated, the end cap 20 covers the shell 30.
  • the shell 30 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 30 can be determined according to the specific shape and size of the electrode assembly 10.
  • the material of the shell 30 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.
  • the electrode assembly 10 is a component in the secondary battery 100 where electrochemical reactions occur.
  • One or more electrode assemblies 10 may be included in the housing 30.
  • the electrode assembly 10 is mainly formed by winding or stacking a positive electrode sheet and a negative electrode sheet 1a, and a separator 2 is usually provided between the positive electrode sheet and the negative electrode sheet 1a.
  • the parts of the positive electrode sheet and the negative electrode sheet 1a with active materials constitute the main body of the electrode assembly 10, and the parts of the positive electrode sheet and the negative electrode sheet 1a without active materials each constitute a tab.
  • the positive electrode tab and the negative electrode tab may be located together at one end of the main body or respectively at both ends of the main body.
  • the positive electrode active material and the negative electrode active material react with the electrolyte, and the tabs connect the electrode terminals 201 to form a current loop.
  • the present application provides an electrode assembly 10.
  • the electrode assembly 10 includes: a plurality of pole pieces 1 and a diaphragm 2.
  • the plurality of pole pieces 1 are stacked in sequence, and the diaphragm 2 is arranged between each two adjacent pole pieces 1; between two adjacent pole pieces 1, a reserved gap 3 is formed between the diaphragm 2 and at least one pole piece 1, and the spacing of the reserved gap 3 is recorded as D.
  • the spacing D tends to increase from any edge of the diaphragm 2 to the middle of the diaphragm 2, wherein, when the electrode assembly 10 is a winding structure, the preset direction S is the width direction of the pole piece 1; when the electrode assembly 10 is a laminated structure, the preset direction S is the width direction or length direction of the pole piece 1.
  • the electrode sheet 1 may include a positive electrode sheet and a negative electrode sheet 1a.
  • the number of electrode sheets 1 may be two or more.
  • two relatively long negative electrode sheets 1a and positive electrode sheets may be stacked in sequence; or, when the electrode assembly 10 is prepared in a stacking manner, multiple electrode sheets 1 may be stacked in sequence.
  • the polarities of two adjacent electrode sheets 1 are usually opposite, that is, one electrode sheet 1 is a positive electrode sheet and the other is a negative electrode sheet 1a.
  • the negative electrode sheet 1a may be wound 1 to 2 more times in the outermost circle, which means that at the outermost circle, there are also two adjacent electrode sheets 1 that are both negative electrode sheets 1a.
  • the preset direction S should be understood as: the width direction or length direction on the pole piece 1.
  • the two edges of the pole piece 1 and the diaphragm 2 along the length direction of the pole piece 1 are respectively rolled on the innermost circle and the outermost circle, so that the larger gap between each layer of the pole piece 1 and the diaphragm 2 occurs at the two edges along the width direction of the pole piece 1 during cyclic charge and discharge.
  • the preset direction S is considered to be the width direction of the pole piece 1; when the electrode assembly 10 is a laminated structure, a larger gap will occur at any edge during cyclic charge and discharge. Therefore, the preset direction S can consider the width direction or length direction of the pole piece 1.
  • the spacing of the reserved gap 3 can increase from any edge to the middle.
  • the length direction of the pole piece 1 can be understood as the coating direction of the pole piece 1, and the width direction of the pole piece 1 is the direction perpendicular to the coating direction of the pole piece 1.
  • the preset direction S is the width direction of the electrode 1. In this way, when preparing the electrode 1 or the diaphragm 2, it is only necessary to design the coating surface 400 of the mold to have an uneven thickness along its own width direction to continuously process uneven electrode sheets 1 or diaphragms 2, which is convenient for preparation.
  • the middle part of the diaphragm 2 refers to the geometric center of the diaphragm 2 in the preset direction S, and the "increasing trend" refers to a gradual increase; or first increasing and then remaining unchanged; or first increasing, then remaining unchanged, and then increasing again, etc.
  • the reserved gap 3 refers to the space between the diaphragm 2 and the electrode 1, which allows the electrode 1 to expand outward. In this way, the contact between the diaphragm 2 and the edge of the electrode 1 (such as the overhang area on the negative electrode 1a) can be increased, the fluffy problem at the end of the electrode assembly 10 can be reduced, and the dynamics can be improved.
  • the reserved gap 3 is designed between the electrode 1 and the diaphragm 2, which is conducive to reducing the increase of the macro expansion force on the electrode assembly 10.
  • the reserved gap 3 there are many ways to form the reserved gap 3, such as: designing a recessed surface of the diaphragm 2; or designing a recessed surface of the pole piece 1; or, simultaneously recessing the surfaces of the diaphragm 2 and the pole piece 1.
  • a surface of the diaphragm 2 facing the reserved gap 3 is defined as a mating surface 23.
  • the middle area of the mating surface 23 in the preset direction S is recessed along a side away from the corresponding pole piece 1.
  • the corresponding pole piece 1 refers to the pole piece 1 corresponding to the mating surface 23 , and a reserved gap 3 is formed between the mating surface 23 and the pole piece 1 .
  • the middle area of the mating surface 23 in the preset direction S is concavely designed so that the edge of the mating surface 23 in the preset direction S is higher than the middle of the mating surface 23, so that a reserved gap 3 is formed between the diaphragm 2 and the pole piece 1.
  • the edge of the diaphragm 2 is thickened to suppress the edge of the pole piece 1 and avoid the problem of wrinkling of the pole piece 1.
  • the width of the middle area in the preset direction S is not specifically limited in this embodiment, and only needs to be greater than 0 and less than the overall width of the mating surface 23 in the preset direction S.
  • mating surface 23 concave in the preset direction S for example: designing the coating 22 on the diaphragm 2 to be thick on both sides and thin in the middle; or designing the substrate 21 of the diaphragm 2 to be thick on both sides and thin in the middle.
  • the mating surface 23 of the diaphragm 2 is designed to be concave, so that an effective reserved gap 3 is formed between the diaphragm 2 and the pole piece 1, reducing the problem of lithium deposition; at the same time, the thick design at both ends can suppress the edge of the pole piece 1 to avoid the problem of wrinkling of the pole piece 1.
  • the mating surface 23 includes a first plane segment 231 and two first curved segments 232 connected to both sides of the first plane segment 231. From the side of the first curved segment 232 close to the first plane segment 231 to the side of the first curved segment 232 away from the first plane segment 231, the first curved segment 232 is arranged along an arc-shaped depression toward the corresponding pole piece 1.
  • the mating surface 23 is divided into three parts in the preset direction S: the middle part is a plane, and the two side parts are curved surfaces, so that the reserved gap 3 is formed into a structure with a large middle and small ends.
  • the first curved surface segment 232 is concave from a side close to the first plane segment 231 to a side away from the first plane segment 231 and moves toward the corresponding pole piece 1 .
  • the first curved surface segment 232 formed in this way is an arc-shaped curved surface structure.
  • the mating surface 23 is designed to be a first plane segment 231 and two first curved segments 232, so that a reserved gap 3 of an arc-shaped recessed structure is formed between the mating surface 23 and the pole piece 1, thereby ensuring better contact between the edge of the pole piece 1 and the diaphragm 2 after expansion, reducing the fluffy problem at the end of the electrode assembly 10 and improving the embedding and disengaging dynamics.
  • the projection of the first curved surface segment 232 in the plane formed by the thickness direction T of the pole piece 1 and the preset direction S is the first contour line 23a.
  • the coordinate axis is constructed with one end of the first contour line 23a close to the first plane segment 231 as the origin, the direction parallel to the preset direction S as the X-axis, and the direction parallel to the thickness direction T of the pole piece 1 as the Y-axis.
  • the first contour line 23a is a projection of the first curved surface segment 232 in a plane formed by the thickness direction T of the pole piece 1 and the preset direction S.
  • the first contour line 23a is a curve, which conforms to a cubic function relationship in the formed coordinate axis.
  • d0 can be understood as the height difference between the side of the first curved surface segment 232 away from the first plane segment 231 and the first plane segment 231
  • M1 can be understood as the width of the first curved surface segment 232 in the preset direction S.
  • the functional expression of F(X) is determined by measuring the d0 and M1 values of the diaphragm 2 in the competitor; then, take any point on the first curved surface segment 232 in the competitor to determine whether it satisfies the expression of F(X) of the present application.
  • correction coefficients a and b there are many possible values of the correction coefficients a and b in the function expression, and they only need to satisfy the relationship 0 ⁇ a ⁇ b ⁇ 1.
  • condition a satisfies is: 0 ⁇ a ⁇ 1/2, and 1/2 ⁇ b ⁇ 1; or, 0 ⁇ a ⁇ 1/3, and 2/3 ⁇ b ⁇ 1, etc.
  • the curve relationship of the first curved surface segment 232 satisfies the function expression of F(X), so that the edge of the expanded electrode 1 can better contact with the diaphragm 2, reduce the gap at the edge (such as the overhang area of the electrode 1, etc.), improve the insertion and extraction dynamics, reduce the lithium plating problem, and improve the performance of the secondary battery 100.
  • the overall width of the mating surface 23 is recorded as L1
  • the width of the first curved surface segment 232 is recorded as M1
  • the condition satisfied by M1 and L1 is: 1/6 ⁇ M1/L1 ⁇ 1/2.
  • M1/L1 is designed to be between 1/6 and 1/2, and the curvature of the first curved surface segment 232 is reasonably optimized, so that the edge of the diaphragm 2 can better contact the edge of the expanded electrode 1, effectively improving the lithium plating problem.
  • the diaphragm 2 includes a substrate 21 and coatings 22 disposed on two opposite sides of the substrate 21 , and a reserved gap 3 is formed between at least one coating 22 and the corresponding pole piece 1 .
  • the separator 2 refers to a structure between the positive electrode sheet and the negative electrode sheet 1a, and its function is to allow lithium ions to pass freely between the positive electrode sheet and the negative electrode sheet 1a.
  • the substrate 21 refers to a porous structure that allows lithium ions to pass freely, and its material can be selected from a variety of options, such as but not limited to: single-layer polyethylene, single-layer polypropylene, double-layer polyethylene, double-layer polypropylene, multi-layer polyethylene, multi-layer polypropylene, or polyethylene and polypropylene laminated layers.
  • the coating 22 refers to a slurry structure coated on the substrate 21, and its slurry components may include a binder, a thickener, a diaphragm 2 coating (such as Al 2 O 3 ), an insulating coating 22 , a stabilizer, etc.
  • the binder may be but is not limited to at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polyvinyl alcohol, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, fluorinated rubber, LA133, LA132, styrene-butadiene rubber, polyacrylate, and polyvinylidene fluoride.
  • the electrode 1 may be a negative electrode 1a.
  • the reserved gap 3 is formed between the coating 22 and the pole piece 1 to ensure that the edge of the diaphragm 2 can better contact with the expanded pole piece 1, reduce the gap between the two, and ensure the embedding and disembedding dynamics.
  • the thickness of the coating 22 is denoted as h1 , and in a preset direction S, the thickness h1 increases from the middle of the coating 22 to any edge of the coating 22 .
  • the middle of the coating 22 refers to the geometric center of the coating 22 in the preset direction S. If the thickness h1 increases from the middle of the coating 22 to any edge of the coating 22, it means that the surface of the coating 22 presents a concave structure.
  • the surface of the coating 22 is designed to be concave, which is conducive to filling the gap between the edge of the pole piece 1 and the diaphragm 2.
  • one of two adjacent electrode sheets 1 is a negative electrode sheet 1 a
  • a reserved gap 3 is formed between the separator 2 and the negative electrode sheet 1 a .
  • the negative electrode sheet 1a is prone to expansion during the cycle, resulting in a larger expansion amount of the middle portion of the negative electrode sheet 1a than the edge of the negative electrode sheet 1a, and a larger gap between the edge of the electrode sheet 1 and the diaphragm 2.
  • a reserved gap 3 is set between the diaphragm 2 and the negative electrode sheet 1a, so that the gap between the edge of the expanded negative electrode sheet 1a and the diaphragm 2 is reduced, the dynamics is improved, and the lithium precipitation problem is improved.
  • a surface of the pole piece 1 for forming the reserved gap 3 is defined as an optimized surface 13.
  • the optimized surface 13 is recessed in the middle region in the preset direction S along the side away from the corresponding diaphragm 2.
  • the middle area of the optimized surface 13 in the preset direction S is concavely designed so that the edge of the optimized surface 13 in the preset direction S is higher than the middle of the optimized surface 13, so that a reserved gap 3 is formed between the diaphragm 2 and the pole piece 1.
  • the edge of the optimized surface 13 is thickened so that the edge of the optimized surface 13 can contact the diaphragm 2 to avoid wrinkling of the pole piece 1.
  • the width of the middle area in the preset direction S is not specifically limited in this embodiment, and only needs to be greater than 0 and less than the overall width of the mating surface 23 in the preset direction S.
  • the optimized surface 13 of the pole piece 1 is concavely designed to form an effective reserved gap 3 between the diaphragm 2 and the pole piece 1, thereby reducing the problem of lithium deposition.
  • the thick design at both ends can suppress the edge of the pole piece 1 to avoid the problem of wrinkling of the pole piece 1.
  • the optimized surface 13 includes a second plane segment 131 and two second curved surface segments 132 connected to both sides of the second plane segment 131. From the side of the second curved surface segment 132 close to the second plane segment 131 to the side of the second curved surface segment 132 away from the second plane segment 131, the second curved surface segment 132 is arranged along an arc-shaped depression away from the corresponding side of the diaphragm 2.
  • the optimized surface 13 is divided into three parts in the preset direction S: the middle part is a plane, and the two side parts are curved surfaces, so that the reserved gap 3 is formed into a structure with a large middle and small ends.
  • the second curved surface segment 132 is concave from a side close to the second plane segment 131 to a side away from the second plane segment 131 and moves toward the corresponding diaphragm 2 .
  • the second curved surface segment 132 formed in this way is an arc-shaped curved surface structure.
  • the optimized surface 13 is designed as a second plane segment 131 and two second curved surface segments 132, so that a reserved gap 3 of an arc-shaped recessed structure is formed between the optimized surface 13 and the diaphragm 2, thereby ensuring better contact between the edge of the pole piece 1 and the diaphragm 2 after expansion, reducing the fluffy problem at the end of the electrode assembly 10 and improving the embedding and unembedding dynamics.
  • the projection of the second curved surface segment 132 in the plane formed by the thickness direction T of the pole piece 1 and the preset direction S is the second contour line 13a.
  • the second contour line 13a is a projection of the second curved surface segment 132 in a plane formed by the thickness direction T of the pole piece 1 and the preset direction S.
  • the second contour line 13a is a curve, and in the formed coordinate axis, it also conforms to a cubic function relationship of one variable.
  • d0 can be understood as the height difference between the side of the second curved surface segment 132 away from the second plane segment 131 and the second plane segment 131
  • M1 can be understood as the width of the second curved surface segment 132 in the preset direction S.
  • correction coefficients a and b there are many possible values of the correction coefficients a and b in the function expression, and they only need to satisfy the relationship 0 ⁇ a ⁇ b ⁇ 1.
  • condition a satisfies is: 0 ⁇ a ⁇ 1/2, and 1/2 ⁇ b ⁇ 1; or, 0 ⁇ a ⁇ 1/3, and 2/3 ⁇ b ⁇ 1, etc.
  • the curve relationship of the second curved surface segment 132 satisfies the function expression of F(X), so that the edge of the expanded electrode 1 can better contact with the diaphragm 2, reduce the gap at the edge (such as the overhang area of the electrode 1, etc.), improve the insertion and extraction dynamics, reduce the lithium plating problem, and improve the performance of the secondary battery 100.
  • the overall width of the optimized surface 13 is recorded as L2
  • the width of the second curved surface segment 132 is recorded as M1
  • the condition satisfied by M1 and L is: 1/6 ⁇ M1/L2 ⁇ 1/2.
  • M1/L2 is designed to be between 1/6 and 1/2, and the curvature of the second curved surface segment 132 is reasonably optimized, so that the edge of the diaphragm 2 can better contact the edge of the expanded electrode 1, effectively improving the lithium plating problem.
  • the pole piece 1 includes a current collector 11 and active layers 12 disposed on two opposite sides of the current collector 11 , and a reserved gap 3 is formed between at least one active layer 12 and the corresponding diaphragm 2 .
  • the current collector 11 refers to a component that can not only carry active materials, but also collect and output the current generated by the electrode active materials.
  • the material of the current collector 11 can be selected differently according to the polarity of the electrode 1.
  • the material of the current collector 11 can be but not limited to metal materials such as aluminum and nickel, and can also be composite materials such as conductive resin, titanium-nickel shape memory alloy, and carbon-coated aluminum foil.
  • the material of the current collector 11 can be but not limited to metal materials such as copper, and of course it can also be composite materials such as conductive resin, titanium-nickel shape memory alloy, etc.
  • the active layer 12 refers to the active material coated on the current collector 11, and its material can be selected according to the polarity of the electrode 1.
  • the material of the active material layer can be but not limited to lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium iron phosphate, ternary materials, etc.
  • the material of the active material layer can be but not limited to graphite, silicon oxide, etc.
  • the reserved gap 3 is formed between the active layer 12 and the diaphragm 2 to ensure that the edge of the diaphragm 2 can better contact with the expanded pole piece 1, reduce the gap between the two, and ensure the embedding and disembedding dynamics.
  • the thickness of the active layer 12 is denoted as h2 , and in a preset direction S, the thickness h2 increases from the middle of the active layer 12 to any edge of the active layer 12 .
  • the middle of the active layer 12 refers to the geometric center of the active layer 12 in the preset direction S. If the thickness h2 increases from the middle of the active layer 12 to any edge of the active layer 12 , it means that the surface of the active layer 12 presents a concave structure.
  • the surface of the active layer 12 is designed to be concave, which is conducive to filling the gap between the edge of the pole piece 1 and the diaphragm 2.
  • the present application provides a secondary battery 100 including the electrode assembly 10 in any of the above solutions.
  • the present application provides an electrical device, including the secondary battery 100 in the above solution.
  • the present application provides a method for preparing an electrode assembly 10, which is used to prepare the electrode assembly 10 in any of the above schemes, comprising the following steps:
  • step S100 and step S200 at least one of the first mold 200 and the second mold 300 has a coating surface 400 with an arc-shaped convex structure in the middle, so that when coating the pole piece 1 or the diaphragm 2, an arc-shaped concave structure is formed on the surface of the pole piece 1 or the diaphragm 2.
  • both the first mold 200 and the second mold 300 can be designed as a roller structure, that is, each coating surface 400 is a cylindrical surface.
  • step S100 and step S200 may not be limited, for example: step S100 may be executed first, and then step S200; or, step S200 may be executed first, and then step S100; or, step S100 and step S200 may be executed simultaneously, etc.
  • the stacking operation refers to alternately stacking a plurality of electrode sheets 1 and diaphragms 2 in sequence; at the same time, the winding operation refers to arranging and stacking the positive electrode sheet, diaphragm 2 and negative electrode sheet 1a, and winding the stacked structure along the length direction of the electrode sheet 1 to form a flat winding structure.
  • At least one coating surface 400 of the first mold 200 and the second mold 300 is designed as an arc-shaped convex surface, so that the surface of the diaphragm 2 or the pole piece 1 forms an arc-shaped concave structure, ensuring that there is a reserved gap 3 between the diaphragm 2 and the pole piece 1, thereby reducing the lithium plating problem and the wrinkling problem of the pole piece 1.
  • the coating surface 400 of the first mold 200 and/or the second mold 300 is designed to be divided into three parts: the middle part is a plane, and both side parts are curved surfaces, so that the reserved gap 3 is formed into a structure with a large middle and small ends.
  • the third contour line 421 of the third curved surface segment 420 is designed as a curve, that is, in the constructed coordinate axis, it conforms to a univariate cubic function relationship.
  • the coating direction H refers to the relative linear motion direction of the coating surface 400 relative to the electrode 1 or the diaphragm 2 during the coating process.
  • the coating surface 400 has a backward linear motion direction relative to the electrode 1 or the diaphragm 2.
  • the coating direction H can also be directly understood as the length direction of the electrode 1 or the diaphragm 2. It should be noted that the coating direction H can be referred to as the direction perpendicular to the paper inward in FIG. 10.
  • the curve relationship of the third curved surface segment 420 satisfies the function expression of F(X), so that the edge of the expanded electrode 1 can better contact with the diaphragm 2, reduce the gap at the edge (such as the overhang area of the electrode 1, etc.), improve the insertion and extraction dynamics, reduce the lithium plating problem, and improve the performance of the secondary battery 100.
  • the present application provides a negative electrode sheet 1a and a separator 2.
  • the thickness of the coating 22 of the separator 2 is designed to be non-uniform along its width direction, that is, a curved surface that is thin in the middle and thick at both ends.
  • the thickness of the active layer 12 of the negative electrode sheet 1a is designed to be non-uniform along its width direction, that is, a curved surface that is thin in the middle and thick at both ends.
  • the thickness of the coating surface 400 of at least one of the first mold 200 and the second mold 300 can be designed to be a curved surface that is thick in the middle and thin at both ends. Each curved surface satisfies a univariate cubic function expression in the constructed coordinate axis.
  • the positive electrode active material ternary material nickel cobalt manganese (NCM811), the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) are mixed evenly in a mass ratio of 97:2:1 and added into the solvent NMP to prepare the positive electrode slurry; the positive electrode slurry is evenly coated on the positive electrode collector 11 aluminum foil, dried at 85°C and then cold pressed, and then die-cut and slit to prepare the lithium-ion battery positive electrode sheet.
  • the negative electrode active material graphite, the conductive agent acetylene black, the thickener sodium hydroxymethyl cellulose (CMC), and the binder styrene butadiene rubber (SBR) are added to the solvent water in a mass ratio of 96:2:1:1, mixed evenly and made into a negative electrode slurry; the negative electrode slurry is evenly coated on the copper foil of the negative electrode collector 11, dried at 85°C and then cold pressed to make a lithium ion battery negative electrode sheet 1a.
  • a polyethylene microporous film is used as the substrate 21 of the porous diaphragm 2.
  • Inorganic alumina powder, polyvinylpyrrolidone and acetone solvent are evenly mixed in a weight ratio of 3:1.5:5.5 to form a slurry, which is coated on one side of the substrate 21 and dried to obtain the diaphragm 2.
  • Lithium hexafluorophosphate is dissolved in a mixed solvent of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate (the volume ratio of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate is 1:2:1) to obtain a lithium ion battery electrolyte.
  • the positive electrode sheet, the negative electrode sheet 1a and the separator 2 are wound to obtain an electrode assembly 10, and then the secondary battery 100 is manufactured through the processes of packaging, liquid injection, formation, exhaust and the like.
  • the coordinate position of Q is (10 mm, 0.02 mm)
  • the coordinate position of R is (20 mm, 0.04 mm).
  • the structure is basically the same as that of Example 1, except that: point R is above the curve corresponding to the function of F(X), that is, the coordinate position of R is (20 mm, 0.06 mm).
  • the structure is basically the same as that of Example 1, except that point R is below the curve corresponding to the function of F(X), that is, the coordinate position of R is (20 mm, 0.02 mm).
  • the secondary battery 100 of the above embodiment and comparative example was cycled at 0.5C/1C rate for 200cls respectively, and the overhang (the part of the negative electrode sheet 1a that exceeds the positive electrode sheet in its width direction) between the upper and lower positive electrode sheets and the negative electrode sheet 1a was observed to see whether a 20mm purple spot and lithium deposition occurred.
  • the specific parameters can be referred to Table 1.

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Abstract

一种电极组件（10）及其制备方法、二次电池（100）和用电装置，在隔膜（2）至少一表面与对应的极片（1）之间形成预留间隙（3），并使得预留间隙（3）的间距D沿极片（1）的预设方向（S）从隔膜（2）的任一边缘至隔膜（2）的中部呈增大趋势，预留间隙（3）呈中间大、两端小的结构。在循环充放电过程中，极片（1）沿自身宽度方向上的中间部分相对于两边缘发生更大的膨胀时，会更好地收容在预留间隙（3）中。如此，即便极片（1）发生膨胀，膨胀后的极片（1）能与隔膜（2）保持良好的接触，避免极片（1）中间部分因较大膨胀量抵触在隔膜（2）上而导致隔膜（2）的边缘与极片（1）之间的间距增大，改善极片（1）边缘处的脱嵌动力学，减少析锂现象发生，从而提升二次电池（100）的性能。

Description

电极组件及其制备方法、二次电池和用电装置 技术领域
本申请涉及电池技术领域，特别是涉及电极组件及其制备方法、二次电池和用电装置。
背景技术
随着二次电池应用领域的不断扩大，其市场的需求量不断地扩增，对于二次电池的性能要求也越来越高。然而，二次电池在循环充放电后，电极组件中的极片通常会发生膨胀，尤其在负极片上，导致极片上沿自身宽度方向的边缘与隔膜之间间隙增大，恶化动力学，易出现析锂问题，影响二次电池的性能。
发明内容
基于此，有必要提供一种电极组件及其制备方法、二次电池和用电装置，减少电极组件循环充放电中边缘处的间隙，改善动力学，减少析锂现象发生，提升二次电池的性能。
第一方面，本申请提供了一种电极组件，包括：若干极片，依次层叠设置；隔膜，隔设于每相邻两个极片之间；在相邻两个极片之间，隔膜与至少一个极片之间形成预留间隙，预留间隙的间距记为D；在极片的预设方向上，间距D自隔膜的任一边缘至隔膜的中部呈增大趋势，其中，当电极组件为卷绕结构时，预设方向为极片的宽度方向；当电极组件为叠片结构时，预设方向为极片的宽度方向或长度方向。
上述的电极组件，在隔膜至少一表面与对应的极片之间形成预留空间，并将预留空间的间距D沿极片的预设方向从隔膜的任一边缘至隔膜的中部呈增大趋势，使得预留空间呈中间大、两端小的结构。这样在循环充放电过程中，极片沿自身宽度方向上的中间部分相对于两边缘发生更大的膨胀时，会更好地收容在预留空间中。如此，使得即便发生膨胀后的极片能与隔膜保持良好的接触，避免极片中间部分因较大膨胀量抵触在隔膜上而导致隔膜的边缘与极片之间的间隙增大，改善极片边缘处上的脱嵌动力学，减少析锂现象发生，从而提升二次电池的性能。
在一些实施例中，隔膜朝向预留间隙的一表面定义为配合面，配合面在预设方向上的中间区域沿背离对应的极片一侧凹陷设置。如此，将隔膜的配合面凹陷设计，使得隔膜与极片之间形成有效的预留间隙，减少析锂问题；同时，利用两端厚设计，可压制极片的边缘，避免极片发生打皱的问题。
在一些实施例中，在预设方向上，配合面包括第一平面段及连接于第一平面段两侧的 两个第一曲面段；从第一曲面段靠近第一平面段一侧至第一曲面段远离第一平面段的一侧，第一曲面段沿朝对应的极片一侧弧形凹陷设置。如此，将配合面设计为第一平面段和两个第一曲面段，使得配合面与极片之间形成弧形凹陷结构的预留间隙，从而保证膨胀后极片的边缘与隔膜更好接触，减少电极组件端部蓬松问题，改善脱嵌动力学。
在一些实施例中，第一曲面段在极片的厚度方向与预设方向构成的平面内的投影为第一轮廓线，以第一轮廓线靠近第一平面段的一端为原点，平行于预设方向的方向为X轴，平行于极片的厚度方向的方向为Y轴构建坐标轴；第一轮廓线满足的函数关系为：F(X)＝AX 3+BX 2+CX，A＝d0×(4.5+13.5a-13.5×b)/M1 3，B＝d0×(-4.5-22.5a-18×b)/M1 2，C＝d0×(1+9a+31.5b)/M1，式中，F(x)为第一轮廓线在Y轴上的取值，X为第一轮廓线在X轴上的取值，d0为第一轮廓线远离第一平面段的一端在Y轴上的取值，M1为第一轮廓线远离第一平面段的一端在X轴上的取值，a与b均为修正系数，且0＜a＜b＜1。如此，将第一曲面段的曲线关系满足为F(X)的函数表达式，使得膨胀后的极片边缘能更好与隔膜接触，减少边缘处的间隙，改善脱嵌动力学，减少析锂问题，提升二次电池的性能。
在一些实施例中，在预设方向上，配合面的整体宽度记为L1，第一曲面段的宽度记为M1，M1与L1满足的条件为：1/6＜M1/L1＜1/2。如此，将M1/L1设计在1/6～1/2之间，合理优化第一曲面段的曲率，使得隔膜的边缘能更好接触在膨胀后极片的边缘上，有效改善析锂问题。
在一些实施例中，隔膜包括基材及设于基材相对两侧面的涂层，至少一涂层与对应的极片之间形成预留间隙。如此，利用涂层与极片之间形成预留间隙，保证隔膜边缘能更好与膨胀后的极片接触，减少两者之间的间隙，保证脱嵌动力学。
在一些实施例中，涂层的厚度记为h1，在预设方向上，厚度h1从涂层的中部至涂层的任一边缘增大。如此，利用涂层不均匀厚度的涂覆，使得涂层的表面呈凹面设计，从而有利于填补极片边缘与隔膜之间的间隙。
在一些实施例中，在相邻两个极片中，之一为负极片，隔膜与负极片之间形成预留间隙。如此，将隔膜与负极片之间设置预留间隙，使得膨胀后的负极片边缘与隔膜之间间隙缩小，提升动力学，改善析锂问题。
在一些实施例中，极片上用于形成预留间隙的一表面定义为优化面，优化面在预设方向上的中间区域沿背离对应的隔膜一侧凹陷设置。如此，将极片的优化面凹陷设计，使得隔膜与极片之间形成有效的预留间隙，减少析锂问题；同时，利用两端厚设计，可压制极片的边缘，避免极片发生打皱的问题。
在一些实施例中，在预设方向上，优化面包括第二平面段及连接于第二平面段两侧的 两个第二曲面段，从第二曲面段靠近第二平面段一侧至第二曲面段远离第二平面段的一侧，第二曲面段沿背离对应的隔膜一侧弧形凹陷设置。如此，将优化面设计为第二平面段和两个第二曲面段，使得优化面与隔膜之间形成弧形凹陷结构的预留间隙，从而保证膨胀后极片的边缘与隔膜更好接触，减少电极组件端部蓬松问题，改善脱嵌动力学。
在一些实施例中，第二曲面段在极片的厚度方向与预设方向构成的平面内的投影为第二轮廓线，以第二轮廓线靠近第二平面段的一端为原点，平行于预设方向的方向为X轴，平行于极片的厚度方向的方向为Y轴构建坐标轴；第二轮廓线满足的函数关系为：F(X)＝AX 3+BX 2+CX，A＝d0×(4.5+13.5a-13.5×b)/M1 3，B＝d0×(-4.5-22.5a-18×b)/M1 2，C＝d0×(1+9a+31.5b)/M1，式中，F(x)为第二轮廓线在Y轴上的取值，X为第二轮廓线在X轴上的取值，d0为第二轮廓线远离第二平面段的一端在Y轴上的取值，M1为第二轮廓线远离第二平面段的一端在X轴上的取值，a与b均为修正系数，且0＜a＜b＜1。如此，将第二曲面段的曲线关系满足为F(X)的函数表达式，使得膨胀后的极片边缘能更好与隔膜接触，减少边缘处的间隙，改善脱嵌动力学，减少析锂问题，提升二次电池的性能。
在一些实施例中，在预设方向上，优化面的整体宽度记为L2，第二曲面段的宽度记为M1，M1与L满足的条件为：1/6＜M1/L2＜1/2。如此，将M1/L2设计在1/6～1/2之间，合理优化第二曲面段的曲率，使得隔膜的边缘能更好接触在膨胀后极片的边缘上，有效改善析锂问题。
在一些实施例中，极片包括集流体及设于集流体相对两侧面的活性层，至少一活性层与对应的隔膜之间形成预留间隙。如此，利用活性层与隔膜之间形成预留间隙，保证隔膜边缘能更好与膨胀后的极片接触，减少两者之间的间隙，保证脱嵌动力学。
在一些实施例中，活性层的厚度记为h2，在预设方向上，厚度h2从活性层的中部至活性层的任一边缘增大。如此，利用活性层不均匀厚度的涂覆，使得活性层的表面呈凹面设计，从而有利于填补极片边缘与隔膜之间的间隙。
第二方面，本申请提供了一种二次电池，包括以上任一项的电极组件。
第三方面，本申请提供了一种用电装置，包括以上的二次电池。
第二方面，本申请提供了一种电极组件的制备方法，用于制备以上任一项的电极组件，包括如下步骤：利用第一模具在集流体上涂覆活性层，以获取极片；利用第二模具在基材上涂覆涂层，以获取隔膜，其中，第一模具和/或第二模具的涂覆面在涂覆面的宽度方向上的中间部分弧形凸起设置；将极片与隔膜层叠并进行叠片或卷绕操作。
在一些实施例中，在涂覆面的宽度方向上，第一模具和/或第二模具的涂覆面包括第三平面段及连接于第三平面段两侧的两个第三曲面段，第三曲面段在垂直于涂覆面的涂覆方 向的平面内的投影为第三轮廓线，以第三轮廓线靠近第三平面段的一端为原点，平行于涂覆面的宽度方向的方向为X轴，垂直于涂覆面的宽度方向的方向为Y轴构建坐标轴；第三轮廓线满足的函数关系为：F(X)＝AX 3+BX 2+CX，A＝d0×(4.5+13.5a-13.5×b)/M1 3，B＝d0×(-4.5-22.5a-18×b)/M1 2，C＝d0×(1+9a+31.5b)/M1，式中，F(x)为第三轮廓线在Y轴上的取值，X为第三轮廓线在X轴上的取值，d0为第三轮廓线远离第三平面段的一端在Y轴上的取值，M1为第三轮廓线远离第三平面段的一端在X轴上的取值，a与b均为修正系数，且0＜a＜b＜1。
上述说明仅是本申请技术方案的概述，为了能够更清楚了解本申请的技术手段，而可依照说明书的内容予以实施，并且为了让本申请的上述和其它目的、特征和优点能够更明显易懂，以下特举本申请的具体实施方式。
附图说明
通过阅读对下文优选实施方式的详细描述，各种其他的优点和益处对于本领域普通技术人员将变得清楚明了。附图仅用于示出优选实施方式的目的，而并不认为是对本申请的限制。而且在全部附图中，用相同的附图标号表示相同的部件。在附图中：
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二次电池的分解结构示意图；
图3为本申请一些实施例提供的不均匀隔膜与极片配合结构示意图；
图4为图3中的结构膨胀后示意图；
图5为图3中的涂层结构剖视示意图；
图6为本申请一些实施例提供的不均匀极片与隔膜配合结构示意图；
图7为图6中的活性层结构剖视示意图；
图8为本申请一些实施例提供的电极组件的制备流程示意图；
图9为本申请一些实施例提供的第一模具或第二模具涂覆示意图；
图10为本申请一些实施例提供的涂覆面结构剖视示意图。
1000、车辆；100、二次电池；110、控制器；120、马达；10、电极组件；1、极片；1a、负极片；11、集流体；12、活性层；13、优化面；131、第二平面段；132、第二曲面段；13a、第二轮廓线；2、隔膜；21、基材；22、涂层；23、配合面；231、第一平面段；232、第一曲面段；23a、第一轮廓线；3、预留间隙；20、端盖；201、电极端子；30、壳体；200、第一模具；300、第二模具；400、涂覆面；410、第三平面段；420、第三曲面段；421、第三 轮廓线；S、预设方向；T、厚度方向；N、涂覆面的宽度方向；H、涂覆方向。
具体实施方式
下面将结合附图对本申请技术方案的实施例进行详细的描述。以下实施例仅用于更加清楚地说明本申请的技术方案，因此只作为示例，而不能以此来限制本申请的保护范围。
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。
在本申请实施例的描述中，技术术语“第一”“第二”等仅用于区别不同对象，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量、特定顺序或主次关系。在本申请实施例的描述中，“多个”的含义是两个以上，除非另有明确具体的限定。
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。
在本申请实施例的描述中，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。
在本申请实施例的描述中，术语“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)。
在本申请实施例的描述中，技术术语“中心”“纵向”“横向”“长度”“宽度”“厚度”“上”“下”“前”“后”“左”“右”“竖直”“水平”“顶”“底”“内”“外”“顺时针”“逆时针”“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实施例和简化描述，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实施例的限制。
在本申请实施例的描述中，除非另有明确的规定和限定，技术术语“安装”“相连”“连接”“固定”等术语应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或成一体；也可以是机械连接，也可以是电连接；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或两个元件的相互作用关系。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实施例中的具体含义。
目前，从市场形势的发展来看，动力电池的应用越加广泛。动力电池不仅被应用于水力、火力、风力和太阳能电站等储能电源系统，而且还被广泛应用于电动自行车、电动摩托车、电动汽车等电动交通工具，以及军事装备和航空航天等多个领域。随着动力电池应用领域的不断扩大，其市场的需求量也在不断地扩增。
本申请人注意到，随着二次电池的充放电循环中正极活性物质和负极活性物质嵌入或脱出离子，电池体系副反应堆积厚度及石墨片层剥离等导致二次电池会发生鼓胀，即正极片和负极片向外膨胀。然而，不论是正极片还是负极片，在各自宽度方向上，其中间部分的膨胀量大于边缘部分的膨胀量，呈拱形凸起，抵触并挤压隔膜，导致隔膜的边缘与极片的边缘之间的间隙增大。
若隔膜的边缘与极片的边缘之间的间隙变大，会导致电解液无法有效浸润极片的边缘，从而导致锂离子无法在极片的边缘处进行有效传递，恶化脱嵌动力学，进而导致极片的边缘处发生析锂的问题。
基于此，为解决因极片膨胀而导致极片边缘处的动力学恶化，从而导致析锂出现风险的问题，本申请人经过深入研究，设计了一种电极组件。在相邻两个极片之间，隔膜与至少一个极片之间形成预留间隙。同时预留间隙的间距记为D；在极片的预设方向上，间距D自隔膜的任一边缘至隔膜的中部呈增大趋势。
上述的电极组件，在隔膜至少一表面与对应的极片之间形成预留空间，并将预留空间的间距D沿极片的预设方向从隔膜的任一边缘至隔膜的中部呈增大趋势，使得预留空间呈中间大、两端小的结构。这样在循环充放电过程中，极片沿自身宽度方向上的中间部分相对于两边缘发生更大的膨胀时，会更好地收容在预留空间中。
如此设计，使得即便发生膨胀后的极片能与隔膜保持良好的接触，避免极片中间部分因较大膨胀量抵触在隔膜上而导致隔膜的边缘与极片之间的间隙增大，改善极片边缘处上的脱嵌动力学，减少析锂现象发生，从而提升二次电池的性能。
本申请实施例公开的二次电池可以但不限用于车辆、船舶或飞行器等用电装置中。可以使用具备本申请公开的二次电池等组成该用电装置的电源系统。
本申请实施例提供一种使用二次电池作为电源的用电装置，用电装置可以为但不限于手机、平板、笔记本电脑、电动玩具、电动工具、电瓶车、电动汽车、轮船、航天器等等。其中，电动玩具可以包括固定式或移动式的电动玩具，例如，游戏机、电动汽车玩具、电动轮船玩具和电动飞机玩具等等，航天器可以包括飞机、火箭、航天飞机和宇宙飞船等。
以下实施例为了方便说明，以本申请一实施例的一种用电装置为车辆为例进行说明。
请参照图1，图1为本申请一些实施例提供的车辆1000的结构示意图。车辆1000可 以为燃油汽车、燃气汽车或新能源汽车，新能源汽车可以是纯电动汽车、混合动力汽车或增程式汽车等。车辆1000的内部设置有二次电池100，二次电池100可以设置在车辆1000的底部或头部或尾部。二次电池100可以用于车辆1000的供电，例如，二次电池100可以作为车辆1000的操作电源。车辆1000还可以包括控制器110和马达120，控制器110用来控制二次电池100为马达120供电，例如，用于车辆1000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，二次电池100不仅可以作为车辆1000的操作电源，还可以作为车辆1000的驱动电源，代替或部分地代替燃油或天然气为车辆1000提供驱动动力。
二次电池100可以是多个，多个二次电池100之间可串联或并联或混联，混联是指多个二次电池100中既有串联又有并联。多个二次电池100之间可直接串联或并联或混联在一起，再将多个二次电池100构成的整体容纳于箱体内；当然，电池也可以是多个二次电池100先串联或并联或混联组成电池模块形式，多个电池模块再串联或并联或混联形成一个整体，并容纳于箱体内。电池还可以包括其他结构，例如，该电池还可以包括汇流部件，用于实现多个二次电池100之间的电连接。
其中，每个二次电池100可以为锂硫电池、钠离子电池或镁离子电池，但不局限于此。二次电池100可呈圆柱体、扁平体、长方体或其它形状等。
请参照图2，图2为本申请一些实施例提供的二次电池100的分解结构示意图。二次电池100是指组成电池的最小单元。如图2，二次电池100包括有端盖20、壳体30、电极组件10以及其他的功能性部件。
端盖20是指盖合于壳体30的开口处以将二次电池100的内部环境隔绝于外部环境的部件。不限地，端盖20的形状可以与壳体30的形状相适应以配合壳体30。可选地，端盖20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20在受挤压碰撞时就不易发生形变，使二次电池100能够具备更高的结构强度，安全性能也可以有所提高。端盖20上可以设置有如电极端子201等的功能性部件。电极端子201可以用于与电极组件10电连接，以用于输出或输入二次电池100的电能。在一些实施例中，端盖20上还可以设置有用于在二次电池100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20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20的内侧还可以设置有绝缘件，绝缘件可以用于隔离壳体30内的电连接部件与端盖20，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30是用于配合端盖20以形成二次电池100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30和端盖20可以是独立的部件，可以于壳体30上设置开口，通过在开口处使端盖20盖合开口以形成二次电池100的内 部环境。不限地，也可以使端盖20和壳体30一体化，具体地，端盖20和壳体30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30的内部时，再使端盖20盖合壳体30。壳体30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30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30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是二次电池100中发生电化学反应的部件。壳体30内可以包含一个或更多个电极组件10。电极组件10主要由正极片和负极片1a卷绕或层叠放置形成，并且通常在正极片与负极片1a之间设有隔膜2。正极片和负极片1a具有活性物质的部分构成电极组件10的主体部，正极片和负极片1a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201以形成电流回路。
根据本申请的一些实施例，请参照图3，本申请提供了一种电极组件10。电极组件10包括：若干极片1及隔膜2。若干极片1依次层叠设置，隔膜2隔设于每相邻两个极片1之间；在相邻两个极片1之间，隔膜2与至少一个极片1之间形成预留间隙3，预留间隙3的间距记为D。在极片1的预设方向S上，间距D自隔膜2的任一边缘至隔膜2的中部呈增大趋势，其中，当电极组件10为卷绕结构时，预设方向S为极片1的宽度方向；当电极组件10为叠片结构时，预设方向S为极片1的宽度方向或长度方向。
极片1可包括正极片和负极片1a，在制备电极组件10中，极片1的数量可为两个，也可为两个以上。比如：电极组件10以卷绕方式制备时，可采用两条尺寸较长的负极片1a和正极片依次层叠设置；或者，电极组件10以叠片方式制备时，可采用多个极片1依次叠放等。相邻两个极片1之间的极性通常为相反，即一个极片1为正极片，另一个为负极片1a。当然，在卷绕工艺时，可在最外圈多卷绕1～2圈的负极片1a，这说明在最外圈处，也存在有相邻两个极片1均为负极片1a。
预设方向S应理解为：极片1上的宽度方向或长度方向，当电极组件10为卷绕结构时，极片1和隔膜2沿极片1的长度方向上的两边缘则分别卷在最内圈和最外圈，这样在循环充放电时每层极片1和隔膜2之间的较大间隙则发生在沿极片1宽度方向的两边缘处，此时，预设方向S考虑为极片1的宽度方向；当电极组件10为叠片结构时，循环充放电时，任一边缘处均会发生较大间隙，因此，预设方向S可考虑极片1的宽度方向或者长度方向。当然，电极组件10为叠片结构时，在极片1的长度方向和宽度方向上，预留间隙3的间距可从任一边缘至中部均呈现增大。
其中，为便于理解，极片1的长度方向可理解为极片1涂布的方向，而极片1的宽度 方向则为垂直于极片1涂布方向的方向。
在一些实施例中，不论电极组件10是卷绕结构，还是叠片结构，预设方向S均为极片1的宽度方向，这样在制备极片1或隔膜2时，只需将模具的涂覆面400设计成沿自身宽度方向不均匀厚度即可持续加工出不均匀的极片1或隔膜2，方便制备。
隔膜2的中部是指隔膜2在预设方向S上的几何中心部位，而“增大趋势”是指逐渐增大；或者先增大后不变；又或者，先增大、后不变、再增大等。
预留间隙3是指隔膜2与极片1之间的空间，可供极片1向外发生膨胀。这样，可增加隔膜2与极片1边缘(比如：负极片1a上的overhang区域等)处的接触，减少电极组件10端部的蓬松问题，改善动力学。同时，在极片1与隔膜2之间设计预留间隙3，有利于减少电极组件10上宏观膨胀力的增加。
预留间隙3的形成有多种方式，比如：将隔膜2的表面凹陷设计；或者，将极片1的表面凹陷设计；又或者，同时将隔膜2的表面和极片1的表面同时凹陷等。
在循环充放电过程中，极片1沿自身宽度方向上的中间部分相对于两边缘发生更大的膨胀时，会更好地收容在预留空间中，请参照图4。如此，使得即便发生膨胀后的极片1能与隔膜2保持良好的接触，避免极片1中间部分因较大膨胀量抵触在隔膜2上而导致隔膜2的边缘与极片1之间的间隙增大，改善极片1边缘处上的脱嵌动力学，减少析锂现象发生，从而提升二次电池100的性能。
根据本申请的一些实施例，可选地，请参照图3，隔膜2朝向预留间隙3的一表面定义为配合面23。配合面23在预设方向S上的中间区域沿背离对应的极片1一侧凹陷设置。
对应的极片1是指与配合面23对应的极片1，配合面23与该极片1之间形成有预留间隙3。
配合面23在预设方向S上的中间区域凹陷设计，使得配合面23在预设方向S上的边缘高于配合面23的中部，这样使得隔膜2与极片1之间形成预留间隙3。同时，将隔膜2的边缘增厚设计，可压制极片1的边缘，避免极片1发生打皱的问题。另外，该中间区域在预设方向S上的宽度在本实施例中可不作具体限定，只需满足大于0且小于配合面23在预设方向S上的整体宽度即可。
配合面23在预设方向S上的凹陷，有两种方式，比如：将隔膜2上的涂层22设计为两边厚、中间薄的结构；或者将隔膜2的基材21设计为两边厚、中间薄的结构等。
将隔膜2的配合面23凹陷设计，使得隔膜2与极片1之间形成有效的预留间隙3，减少析锂问题；同时，利用两端厚设计，可压制极片1的边缘，避免极片1发生打皱的问题。
根据本申请的一些实施例，可选地，请参照图5，在预设方向S上，配合面23包括 第一平面段231及连接于第一平面段231两侧的两个第一曲面段232。从第一曲面段232靠近第一平面段231一侧至第一曲面段232远离第一平面段231的一侧，第一曲面段232沿朝对应的极片1一侧弧形凹陷设置。
配合面23在预设方向S上，分为三部分：中间部分为平面、两侧部分均为曲面，这样使得构成的预留间隙3成中间大、两端小的结构。
第一曲面段232是指从靠近第一平面段231一侧开始至远离第一平面段231一侧凹陷并朝向对应的极片1靠拢，这样形成的第一曲面段232为弧形曲面结构。
将配合面23设计为第一平面段231和两个第一曲面段232，使得配合面23与极片1之间形成弧形凹陷结构的预留间隙3，从而保证膨胀后极片1的边缘与隔膜2更好接触，减少电极组件10端部蓬松问题，改善脱嵌动力学。
根据本申请的一些实施例，可选地，请参照图5，第一曲面段232在极片1的厚度方向T与预设方向S构成的平面内的投影为第一轮廓线23a。以第一轮廓线23a靠近第一平面段231的一端为原点，平行于预设方向S的方向为X轴，平行于极片1的厚度方向T的方向为Y轴构建坐标轴。第一轮廓线23a满足的函数关系为：F(X)＝AX 3+BX 2+CX，A＝d0×(4.5+13.5a-13.5×b)/M1 3，B＝d0×(-4.5-22.5a-18×b)/M1 2，C＝d0×(1+9a+31.5b)/M1，式中，F(x)为第一轮廓线23a在Y轴上的取值，X为第一轮廓线23a在X轴上的取值，d0为第一轮廓线23a远离第一平面段231的一端在Y轴上的取值，M1为第一轮廓线23a远离第一平面段231的一端在X轴上的取值，a与b均为修正系数，且0＜a＜b＜1。
第一轮廓线23a为第一曲面段232在极片1的厚度方向T与预设方向S构成的平面内的投影。第一轮廓线23a为曲线，在构成的坐标轴中，符合一元三次函数关系式。
为明确F(X)＝AX 3+BX 2+CX的函数式，请参照图5，在第一轮廓线23a上取四个坐标点：O(0,0)、Q(1/3M1,a*d0)、R(2/3M1,b*d0)、P(M1,d0)，将四个坐标点分别代入F(X)函数式中，并相互联立以得出A、B和C的表达式。其中，d0可理解为第一曲面段232远离第一平面段231的一侧与第一平面段231之间的高度差，M1理解为第一曲面段232在预设方向S上的宽度。当然，在竞品上反向时，通过测量竞品中隔膜2的d0和M1值，确定F(X)的函数表达式；接着，取竞品中的第一曲面段232上的任一点判断是否满足本申请的F(X)的表达式。
函数表达式中的a和b修正系数的取值有多种，只需满足0＜a＜b＜1的关系式即可，例如：a满足的条件为：0＜a＜1/2，且1/2＜b＜1；或者，0＜a≤1/3，且2/3≤b＜1等。
将第一曲面段232的曲线关系满足为F(X)的函数表达式，使得膨胀后的极片1边缘能更好与隔膜2接触，减少边缘处(比如极片1overhang区域处等)的间隙，改善脱嵌动力 学，减少析锂问题，提升二次电池100的性能。
根据本申请的一些实施例，可选地，请参照图5，在预设方向S上，配合面23的整体宽度记为L1，第一曲面段232的宽度记为M1，M1与L1满足的条件为：1/6＜M1/L1＜1/2。
配合面23L1由三部分构成，即L1＝M2+2M1，其中，M2为第一平面段231在预设方向S上的宽度值。
将M1/L1设计在1/6～1/2之间，合理优化第一曲面段232的曲率，使得隔膜2的边缘能更好接触在膨胀后极片1的边缘上，有效改善析锂问题。
根据本申请的一些实施例，可选地，请参照图3，隔膜2包括基材21及设于基材21相对两侧面的涂层22，至少一涂层22与对应的极片1之间形成预留间隙3。
隔膜2是指隔在正极片和负极片1a之间的结构，其作用允许锂离子在正极片与负极片1a之间自由通过。基材21是指能允许锂离子自由通过的多孔结构，其材料有多种选择，比如：可为但不限于单层聚乙烯、单层聚丙烯、双层聚乙烯、双层聚丙烯、多层聚乙烯、多层聚丙烯或者聚乙烯和聚丙烯叠层等。
涂层22是指涂覆在基材21上的浆料结构，其浆料成分可包括粘结剂、增稠剂、隔膜2镀层(如Al 2O 3)、绝缘涂层22、稳定剂等。其中，粘结剂可为但不限于聚偏二氟乙烯、偏二氟乙烯-六氟丙烯、聚乙烯醇、聚四氟乙烯、羧甲基纤维素钠、丁苯橡胶、氟化橡胶、LA133、LA132、苯乙烯-丁二烯橡胶、聚丙烯酸酯、聚偏氟乙烯中至少一种。
隔膜2上仅可一个涂层22与极片1之间具有预留间隙3；或者，隔膜2上两个涂层22分别与极片1之间均具有预留间隙3等。当隔膜2上仅一个涂层22与极片1之间具有预留间隙3时，该极片1可为负极片1a。
利用涂层22与极片1之间形成预留间隙3，保证隔膜2边缘能更好与膨胀后的极片1接触，减少两者之间的间隙，保证脱嵌动力学。
根据本申请的一些实施例，可选地，请参照图5，涂层22的厚度记为h1，在预设方向S上，厚度h1从涂层22的中部至涂层22的任一边缘增大。
涂层22的中部是指在预设方向S上，涂层22的几何中心部位。厚度h1从涂层22的中部至涂层22的任一边缘增大，则说明涂层22的表面呈现凹陷结构。
利用涂层22不均匀厚度的涂覆，使得涂层22的表面呈凹面设计，从而有利于填补极片1边缘与隔膜2之间的间隙。
根据本申请的一些实施例，可选地，请参照图6，在相邻两个极片1中，之一为负极片1a，隔膜2与负极片1a之间形成预留间隙3。
负极片1a在循环过程中，容易发生膨胀，导致负极片1a的中部相比于负极片1a的 边缘的膨胀量更大，极片1边缘与隔膜2之间的间隙则更大。
将隔膜2与负极片1a之间设置预留间隙3，使得膨胀后的负极片1a边缘与隔膜2之间间隙缩小，提升动力学，改善析锂问题。
根据本申请的一些实施例，可选地，请参照图6，极片1上用于形成预留间隙3的一表面定义为优化面13。优化面13在预设方向S上的中间区域沿背离对应的隔膜2一侧凹陷设置。
优化面13在预设方向S上的中间区域凹陷设计，使得优化面13在预设方向S上的边缘高于优化面13的中部，这样使得隔膜2与极片1之间形成预留间隙3。同时，将优化面13的边缘增厚设计，使得优化面13的边缘能接触隔膜2，避免极片1发生打皱的问题。另外，该中间区域在预设方向S上的宽度在本实施例中可不作具体限定，只需满足大于0且小于配合面23在预设方向S上的整体宽度即可。
优化面13在预设方向S上的凹陷，有两种方式，比如：将极片1上的活性层12设计为两边厚、中间薄的结构；或者将极片1的集流体11设计为两边厚、中间薄的结构等。
将极片1的优化面13凹陷设计，使得隔膜2与极片1之间形成有效的预留间隙3，减少析锂问题；同时，利用两端厚设计，可压制极片1的边缘，避免极片1发生打皱的问题。
根据本申请的一些实施例，可选地，请参照图7，在预设方向S上，优化面13包括第二平面段131及连接于第二平面段131两侧的两个第二曲面段132。从第二曲面段132靠近第二平面段131一侧至第二曲面段132远离第二平面段131的一侧，第二曲面段132沿背离对应的隔膜2一侧弧形凹陷设置。
优化面13在预设方向S上，分为三部分：中间部分为平面、两侧部分均为曲面，这样使得构成的预留间隙3成中间大、两端小的结构。
第二曲面段132是指从靠近第二平面段131一侧开始至远离第二平面段131一侧凹陷并朝向对应的隔膜2靠拢，这样形成的第二曲面段132为弧形曲面结构。
将优化面13设计为第二平面段131和两个第二曲面段132，使得优化面13与隔膜2之间形成弧形凹陷结构的预留间隙3，从而保证膨胀后极片1的边缘与隔膜2更好接触，减少电极组件10端部蓬松问题，改善脱嵌动力学。
根据本申请的一些实施例，可选地，请参照图7，第二曲面段132在极片1的厚度方向T与预设方向S构成的平面内的投影为第二轮廓线13a。以第二轮廓线13a靠近第二平面段131的一端为原点，平行于预设方向S的方向为X轴，平行于极片1的厚度方向T的方向为Y轴构建坐标轴；第二轮廓线13a满足的函数关系为：F(X)＝AX 3+BX 2+CX，A＝d0×
(4.5+13.5a-13.5×b)/M1 3，B＝d0×(-4.5-22.5a-18×b)/M1 2，C＝d0×(1+9a+31.5b)/M1，式中， F(x)为第二轮廓线13a在Y轴上的取值，X为第二轮廓线13a在X轴上的取值，d0为第二轮廓线13a远离第二平面段131的一端在Y轴上的取值，M1为第二轮廓线13a远离第二平面段131的一端在X轴上的取值，a与b均为修正系数，且0＜a＜b＜1。
第二轮廓线13a为第二曲面段132在极片1的厚度方向T与预设方向S构成的平面内的投影。第二轮廓线13a为曲线，在构成的坐标轴中，同样符合一元三次函数关系式。
为明确F(X)＝AX 3+BX 2+CX的函数式，在第二轮廓线13a上取四个坐标点：O(0,0)、Q(1/3M1,a*d0)、R(2/3M1,b*d0)、P(M1,d0)，将四个坐标点分别代入F(X)函数式中，并相互联立以得出A、B和C的表达式。其中，d0可理解为第二曲面段132远离第二平面段131的一侧与第二平面段131之间的高度差，M1理解为第二曲面段132在预设方向S上的宽度。当然，在竞品上反向时，通过测量竞品中极片1的d0和M1值，确定F(X)的函数表达式；接着，取竞品中的第二曲面段132上的任一点判断是否满足本申请的F(X)的表达式。
函数表达式中的a和b修正系数的取值有多种，只需满足0＜a＜b＜1的关系式即可，例如：a满足的条件为：0＜a＜1/2，且1/2＜b＜1；或者，0＜a≤1/3，且2/3≤b＜1等。
将第二曲面段132的曲线关系满足为F(X)的函数表达式，使得膨胀后的极片1边缘能更好与隔膜2接触，减少边缘处(比如极片1overhang区域处等)的间隙，改善脱嵌动力学，减少析锂问题，提升二次电池100的性能。
根据本申请的一些实施例，可选地，请参照图7，在预设方向S上，优化面13的整体宽度记为L2，第二曲面段132的宽度记为M1，M1与L满足的条件为：1/6＜M1/L2＜1/2。
优化面13L2由三部分构成，即L2＝M3+2M1，其中，M3为第二平面段131在预设方向S上的宽度值。
将M1/L2设计在1/6～1/2之间，合理优化第二曲面段132的曲率，使得隔膜2的边缘能更好接触在膨胀后极片1的边缘上，有效改善析锂问题。
根据本申请的一些实施例，可选地，请参照图6，极片1包括集流体11及设于集流体11相对两侧面的活性层12，至少一活性层12与对应的隔膜2之间形成预留间隙3。
集流体11是指不仅能承载活性物质，而且还能将电极活性物质产生的电流汇集并输出的部件。集流体11的材料可根据极片1的极性不同有不同的选择，比如：在正极片中，集流体11的材料可为但不限于铝、镍等金属材料，也可为导电树脂、钛镍形状记忆合金、覆碳铝箔等复合材料。在正极片中，集流体11的材料可为但不限于铜等金属材料，当然也可为导电树脂、钛镍形状记忆合金等复合材料。
活性层12是指涂覆在集流体11上的活性物质，其材料可根据极片1的极性进行选择。比如：在正极片中，活性物质层的材料可为但不限于钴酸锂、锰酸锂、镍酸锂、磷酸铁锂、 三元材料等。在负极片1a中，活性物质层的材料可为但不限于石墨、硅氧化物等。
利用活性层12与隔膜2之间形成预留间隙3，保证隔膜2边缘能更好与膨胀后的极片1接触，减少两者之间的间隙，保证脱嵌动力学。
根据本申请的一些实施例，可选地，请参照图7，活性层12的厚度记为h2，在预设方向S上，厚度h2从活性层12的中部至活性层12的任一边缘增大。
活性层12的中部是指在预设方向S上，活性层12的几何中心部位。厚度h2从活性层12的中部至活性层12的任一边缘增大，则说明活性层12的表面呈现凹陷结构。
利用活性层12不均匀厚度的涂覆，使得活性层12的表面呈凹面设计，从而有利于填补极片1边缘与隔膜2之间的间隙。
根据本申请的一些实施例，本申请提供了一种二次电池100，包括以上任一方案中的电极组件10。
根据本申请的一些实施例，本申请提供了一种用电装置，包括以上方案中的二次电池100。
根据本申请的一些实施例，请参照图8与图9，本申请提供了一种电极组件10的制备方法，用于制备以上任一方案中的电极组件10，包括如下步骤：
S100、利用第一模具200在集流体11上涂覆活性层12，以获取极片1；
S200、利用第二模具300在基材21上涂覆涂层22，以获取隔膜2，其中，第一模具200和/或第二模具300的涂覆面400在涂覆面的宽度方向N上的中间部分弧形凸起设置；
S300、将极片1与隔膜2层叠并进行叠片或卷绕操作。
步骤S100和步骤S200中，第一模具200和第二模具300中至少一个，其涂覆面400呈中间部位弧形凸起结构设计，这样在涂覆极片1或隔膜2时，使得极片1或隔膜2的表面形成弧形凹面结构。另，第一模具200和第二模具300均可设计为辊结构，即各自的涂覆面400均为圆柱曲面。
同时，步骤S100和步骤S200的执行顺序可不作限定，比如：可先执行步骤S100，再执行步骤S200；或者，可先执行步骤S200，再执行步骤S100；又或者，同时执行步骤S100和步骤S200等。
步骤S300中，叠片操作是指将若干极片1和隔膜2依次交替叠合；同时，卷绕操作是指将正极片、隔膜2和负极片1a排列叠放，并将叠放后的结构沿极片1的长度方向卷绕，形成扁状的卷绕结构。
利用第一模具200和第二模具300中至少一个涂覆面400设计成弧形凸起面，使得隔膜2或极片1的表面形成弧形凹陷结构，保证隔膜2与极片1之间具有预留间隙3，减少析 锂问题和极片1打皱问题。
根据本申请的一些实施例，可选地，请参照图10，在涂覆面的宽度方向N上，第一模具200和/或第二模具300的涂覆面400包括第三平面段410及连接于第三平面段410两侧的两个第三曲面段420，第三曲面段420在垂直于涂覆面400的涂覆方向H的平面内的投影为第三轮廓线421，以第三轮廓线421靠近第三平面段410的一端为原点，平行于涂覆面的宽度方向N的方向为X轴，垂直于涂覆面的宽度方向N的方向为Y轴构建坐标轴；第三轮廓线421满足的函数关系为：F(X)＝AX 3+BX 2+CX，A＝d0×(4.5+13.5a-13.5×b)/M1 3，B＝d0×(-4.5-22.5a-18×b)/M1 2，C＝d0×(1+9a+31.5b)/M1，式中，F(x)为第三轮廓线421在Y轴上的取值，X为第三轮廓线421在X轴上的取值，d0为第三轮廓线421远离第三平面段410的一端在Y轴上的取值，M1为第三轮廓线421远离第三平面段410的一端在X轴上的取值，a与b均为修正系数，且0＜a＜b＜1。
将第一模具200和/或第二模具300的涂覆面400设计为三部分：中间部分为平面、两侧部分均为曲面，使得构成的预留间隙3成中间大、两端小的结构。
同时将第三曲面段420的第三轮廓线421设计为曲线，即在构成的坐标轴中，符合一元三次函数关系式。
涂覆方向H是指在涂覆过程中，涂覆面400相对极片1或隔膜2之间的相对线性运动方向，比如：极片1或隔膜2在传送辊的作用下向前输送时，涂覆面400则相对极片1或隔膜2具有向后的线性运动方向，当然，也可直接将涂覆方向H理解为极片1或隔膜2的长度方向。需要说明的是，涂覆方向H可参考为图10中垂直纸张向内的方向。
将第三曲面段420的曲线关系满足为F(X)的函数表达式，使得膨胀后的极片1边缘能更好与隔膜2接触，减少边缘处(比如极片1的overhang区域处等)的间隙，改善脱嵌动力学，减少析锂问题，提升二次电池100的性能。
根据本申请的一些实施例，请参照图3至图10，本申请提供了一种负极片1a与隔膜2。将隔膜2的涂层22厚度沿自身宽度方向为非均匀设计，即中间薄，两端厚的曲面。和/或，将负极片1a的活性层12厚度沿自身宽度方向为非均匀设计，即中间薄，两端厚的曲面。另外，可将第一模具200和第二模具300中至少一个的涂覆面400的厚度设计为中间厚、两端薄的曲面。各个曲面在构建的坐标轴中，满足一元三次函数表达式。
为了使本申请的目的、技术方案及优点更加简洁明了，本申请用以下具体实施例进行说明，但本申请绝非仅限于这些实施例。以下所描述的实施例仅为本申请较好的实施例，可用于描述本申请，不能理解为对本申请的范围的限制。应当指出的是，凡在本申请的精神和原则之内所做的任何修改、等同替换和改进等，均应包含在本申请的保护范围之内。
为了更好地说明本申请，下面结合实施例对本申请内容作进一步说明。以下的具体实施例均以宽度为100毫米(mm)，且厚度150微米(μm)的负极片1a为例。
对比例1
正极片
将正极活性物质三元材料镍钴锰(NCM811)、导电剂乙炔黑、粘结剂聚偏氟乙烯(PVDF)按质量比97：2：1混合均匀并加入到溶剂NMP中，制成正极浆料；将正极浆料均匀涂布在正极集流体11铝箔上，在85℃下烘干后冷压，再进行模切、分条，制成锂离子电池正极片。
负极片1a
将负极活性物质石墨、导电剂乙炔黑、增稠剂羟甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比96：2：1：1加入溶剂水中混合均匀并制成负极浆料；将负极浆料均匀涂布在负极集流体11铜箔上，在85℃下烘干后进行冷压，制成锂离子电池负极片1a。
隔膜2
采用聚乙烯微孔薄膜作为多孔隔膜2基材21，将无机三氧化铝粉末、聚乙烯呲咯烷酮、丙酮溶剂按重量比3：1.5：5.5混合均匀制成浆料并涂布于基材21的一面并烘干，得到隔膜2，且隔膜2的表面不设置配合面23，即隔膜2的表面为平面，d0＝0mm。
电解液
将六氟磷酸锂溶解于碳酸乙烯酯、碳酸二甲酯和碳酸甲乙酯的混合溶剂中(碳酸乙烯酯、碳酸二甲酯、碳酸甲乙酯的体积比为1：2：1)，得到锂离子电池电解液。
二次电池100
将上述正极片、负极片1a以及隔膜2进行卷绕，得到电极组件10，之后经过封装、注液、化成、排气等工序，制得二次电池100。
实施例1
与对比例1结构基本相同，不同之处在于：将隔膜2的一表面设计为配合面23，第一曲面段232的M1为30mm，d0为0.08mm，且第一曲面段232上的Q和R点均在上述F(X)的函数所对应曲线上，其中，F(X)函数中的a和b分别为1/4，1/2，且A＝3.33×10 -6，B＝-0.0017，C＝0.051。此时，Q的坐标位置为(10mm,0.02mm)、R的坐标位置为(20mm,0.04mm)。
实施例2
与实施例1结构基本相同，不同之处在于：R点在上述F(X)的函数所对应曲线的上方，即R的坐标位置为(20mm,0.06mm)。
实施例3
与实施例1结构基本相同，不同之处在于：R点在上述F(X)的函数所对应曲线的下方， 即R的坐标位置为(20mm,0.02mm)。
将以上实施例和对比例进行二次电池100分别在0.5C/1C倍率下循环200cls，观察上下正极片和负极片1a之间overhang(负极片1a在自身宽度方向超出正极片的部分)处是否出现20mm的紫斑和析锂，具体参数可参考表1。
表1
Figure PCTCN2022131251-appb-000001
从表1数据可知，对比例1和实施例1～实施例3对比可得出：将隔膜2的一表面凹陷设计，可缩短overhang处紫斑出现的范围；同时，也有效改善overhang处的析锂问题。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述各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，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，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范围，其均应涵盖在本申请的权利要求和说明书的范围当中。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (18)

  1. 一种电极组件(10)，包括：
    若干极片(1)，依次层叠设置；
    隔膜(2)，隔设于每相邻两个所述极片(1)之间；
    在相邻两个所述极片(1)之间，所述隔膜(2)与至少一个所述极片(1)之间形成预留间隙(3)，所述预留间隙(3)的间距记为D；在所述极片(1)的预设方向(S)上，所述间距D自所述隔膜(2)的任一边缘至所述隔膜(2)的中部呈增大趋势，其中，当所述电极组件(10)为卷绕结构时，所述预设方向(S)为所述极片(1)的宽度方向；当所述电极组件(10)为叠片结构时，所述预设方向(S)为所述极片(1)的宽度方向或长度方向。
  2. 根据权利要求1所述的电极组件(10)，其中，所述隔膜(2)朝向所述预留间隙(3)的一表面定义为配合面(23)，所述配合面(23)在所述预设方向(S)上的中间区域沿背离对应的所述极片(1)一侧凹陷设置。
  3. 根据权利要求2所述的电极组件(10)，其中，在所述预设方向(S)上，所述配合面(23)包括第一平面段(231)及连接于所述第一平面段(231)两侧的两个第一曲面段(232)；从所述第一曲面段(232)靠近所述第一平面段(231)一侧至所述第一曲面段(232)远离所述第一平面段(231)的一侧，所述第一曲面段(232)沿朝对应的所述极片(1)一侧弧形凹陷设置。
  4. 根据权利要求3所述的电极组件(10)，其中，所述第一曲面段(232)在所述极片(1)的厚度方向(T)与所述预设方向(S)构成的平面内的投影为第一轮廓线(23a)，以所述第一轮廓线(23a)靠近所述第一平面段(231)的一端为原点，平行于所述预设方向(S)的方向为X轴，平行于所述极片(1)的厚度方向(T)的方向为Y轴构建坐标轴；
    所述第一轮廓线(23a)满足的函数关系为：F(X)＝AX 3+BX 2+CX，A＝d0×(4.5+13.5a-13.5×b)/M1 3，B＝d0×(-4.5-22.5a-18×b)/M1 2，C＝d0×(1+9a+31.5b)/M1，式中，F(x)为所述第一轮廓线(23a)在Y轴上的取值，X为所述第一轮廓线(23a)在X轴上的取值，d0为所述第一轮廓线(23a)远离所述第一平面段(231)的一端在Y轴上的取值，M1为所述第一轮廓线(23a)远离所述第一平面段(231)的一端在X轴上的取值，a与b均为修正系数，且0＜a＜b＜1。
  5. 根据权利要求3所述的电极组件(10)，其中，在所述预设方向(S)上，所述配合面(23)的整体宽度记为L1，所述第一曲面段(232)的宽度记为M1，M1与L1满足的条件为：1/6＜M1/L1＜1/2。
  6. 根据权利要求1-5任一项所述的电极组件(10)，其中，所述隔膜(2)包括基材(21)及设于所述基材(21)相对两侧面的涂层(22)，至少一所述涂层(22)与对应的所述极片(1)之间形成所述预留间隙(3)。
  7. 根据权利要求6所述的电极组件(10)，其中，所述涂层(22)的厚度记为h1，在所述预设方向(S)上，所述厚度h1从所述涂层(22)的中部至所述涂层(22)的任一边缘增大。
  8. 根据权利要求1-7任一项所述的电极组件(10)，其中，在相邻两个所述极片(1)中，之一为负极片(1a)，所述隔膜(2)与所述负极片(1a)之间形成所述预留间隙(3)。
  9. 根据权利要求1-8任一项所述的电极组件(10)，其中，所述极片(1)上用于形成所述预留间隙(3)的一表面定义为优化面(13)，所述优化面(13)在所述预设方向(S)上的中间区域沿背离对应的所述隔膜(2)一侧凹陷设置。
  10. 根据权利要求9所述的电极组件(10)，其中，在所述预设方向(S)上，所述优化面(13)包括第二平面段(131)及连接于所述第二平面段(131)两侧的两个第二曲面段(132)，从所述第二曲面段(132)靠近所述第二平面段(131)一侧至所述第二曲面段(132)远离所述第二平面段(131)的一侧，所述第二曲面段(132)沿背离对应的所述隔膜(2)一侧弧形凹陷设置。
  11. 根据权利要求10所述的电极组件(10)，其中，所述第二曲面段(132)在所述极片(1)的厚度方向(T)与所述预设方向(S)构成的平面内的投影为第二轮廓线(13a)，以所述第二轮廓线(13a)靠近所述第二平面段(131)的一端为原点，平行于所述预设方向(S)的方向为X轴，平行于所述极片(1)的厚度方向(T)的方向为Y轴构建坐标轴；
    所述第二轮廓线(13a)满足的函数关系为：F(X)＝AX 3+BX 2+CX，A＝d0×(4.5+13.5a-13.5×b)/M1 3，B＝d0×(-4.5-22.5a-18×b)/M1 2，C＝d0×(1+9a+31.5b)/M1，式中，F(x)为所述第二轮廓线(13a)在Y轴上的取值，X为所述第二轮廓线(13a)在X轴上的取值，d0为所述第二轮廓线(13a)远离所述第二平面段(131)的一端在Y轴上的取值，M1为所述第二轮廓线(13a)远离所述第二平面段(131)的一端在X轴上的取值，a与b均为修正系数，且0＜a＜b＜1。
  12. 根据权利要求10所述的电极组件(10)，其中，在所述预设方向(S)上，所述优化面(13)的整体宽度记为L2，所述第二曲面段(132)的宽度记为M1，M1与L满足的条件为：1/6＜M1/L2＜1/2。
  13. 根据权利要求1-12任一项所述的电极组件(10)，其中，所述极片(1)包括集流体(11)及设于所述集流体(11)相对两侧面的活性层(12)，至少一所述活性层(12)与对应的所述隔膜(2)之间形成所述预留间隙(3)。
  14. 根据权利要求13所述的电极组件(10)，其中，所述活性层(12)的厚度记为h2，在所述预设方向(S)上，所述厚度h2从所述活性层(12)的中部至所述活性层(12)的任一边缘增大。
  15. 一种二次电池(100)，包括权利要求1-14任一项所述的电极组件(10)。
  16. 一种用电装置，包括权利要求15所述的二次电池(100)。
  17. 一种电极组件(10)的制备方法，用于制备权利要求1-14任一项所述的电极组件(10)， 包括如下步骤：
    利用第一模具(200)在集流体(11)上涂覆活性层(12)，以获取极片(1)；
    利用第二模具(300)在基材(21)上涂覆涂层(22)，以获取隔膜(2)，其中，所述第一模具(200)和/或所述第二模具(300)的涂覆面(400)在所述涂覆面的宽度方向(N)上的中间部分弧形凸起设置；
    将所述极片(1)与所述隔膜(2)层叠并进行叠片或卷绕操作。
  18. 根据权利要求17所述的电极组件(10)的制备方法，其中，在所述涂覆面的宽度方向(N)上，所述第一模具(200)和/或所述第二模具(300)的涂覆面(400)包括第三平面段(410)及连接于所述第三平面段(410)两侧的两个第三曲面段(420)，所述第三曲面段(420)在垂直于所述涂覆面(400)的涂覆方向(H)的平面内的投影为第三轮廓线(421)，以所述第三轮廓线(421)靠近所述第三平面段(410)的一端为原点，平行于所述涂覆面的宽度方向(N)的方向为X轴，垂直于所述涂覆面的宽度方向(N)的方向为Y轴构建坐标轴；
    所述第三轮廓线(421)满足的函数关系为：F(X)＝AX 3+BX 2+CX，A＝d0×(4.5+13.5a-13.5×b)/M1 3，B＝d0×(-4.5-22.5a-18×b)/M1 2，C＝d0×(1+9a+31.5b)/M1，式中，F(x)为所述第三轮廓线(421)在Y轴上的取值，X为所述第三轮廓线(421)在X轴上的取值，d0为所述第三轮廓线(421)远离所述第三平面段(410)的一端在Y轴上的取值，M1为所述第三轮廓线(421)远离所述第三平面段(410)的一端在X轴上的取值，a与b均为修正系数，且0＜a＜b＜1。
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CN2758991Y (zh) * 2004-12-15 2006-02-15 比亚迪股份有限公司 一种锂离子二次电池
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KR20220126983A (ko) * 2021-03-10 2022-09-19 주식회사 엘지에너지솔루션 리튬 이차전지 및 이를 포함하는 전지팩

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CN2758991Y (zh) * 2004-12-15 2006-02-15 比亚迪股份有限公司 一种锂离子二次电池
CN111540909A (zh) * 2020-05-21 2020-08-14 江苏塔菲尔新能源科技股份有限公司 极片、电芯及电池
KR20220126983A (ko) * 2021-03-10 2022-09-19 주식회사 엘지에너지솔루션 리튬 이차전지 및 이를 포함하는 전지팩

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