Electrode assembly, method for manufacturing electrode assembly, battery cell, battery, and electrical apparatus

Abstract

An electrode assembly, a manufacturing method for the electrode assembly, a battery cell (120), a battery, and an electrical apparatus. The electrode assembly comprises a cathode electrode plate (10) and an anode electrode plate (20), stacked with the cathode electrode plate (10). The cathode electrode plate (10) comprises: a cathode current collector (1); a cathode active material coating (2), provided on a surface of the cathode current collector (1); and a first insulating material coating (3), provided on a side of the cathode active material coating (2) along a winding axial direction. The first insulating material coating (3) comprises a first end section (31), located at an end portion of the first insulating material coating (3) along a winding direction, and a first middle section (32), located in the middle of the first insulating material coating (3) along the winding direction, the size of the first end section (31) being greater than the size of the first middle section (32) along the winding axial direction.

Description

Electrode assembly, method for manufacturing electrode assembly, battery cell, battery, and electrical device

[0001] The present disclosure is based on and claims priority to an application with CN application number CN202410175426.4 and filing date February 7, 2024. The disclosure of the CN application is hereby incorporated into the present disclosure as a whole. Technical Field

[0002] The present disclosure relates to the field of battery technology, and in particular, to an electrode assembly, a method for manufacturing an electrode assembly, a battery cell, a battery, and an electrical device. Background Art

[0003] The application of stacked electrode assemblies in battery cells is becoming increasingly widespread. Research has found that it is currently difficult for electrode assemblies to achieve superior performance. One of the important factors is that the size of the active material of the anode electrode exceeds the size of the active material of the cathode electrode (overhang, OH for short), making it difficult to meet the predetermined requirements. If the requirements are not met, it may be difficult for metal ions to embed into the edge area of ​​the active material area of ​​the anode electrode, resulting in metal precipitation, and the active material of the positive electrode electrode is also difficult to fully play its role, thereby affecting the performance of the electrode assembly. In addition, it will also greatly shorten the cycle life of the electrode assembly, limit the fast charging capacity of the battery, and may also cause safety problems such as combustion and explosion. Summary of the Invention

[0004] The present disclosure aims to provide an electrode assembly, a method for manufacturing an electrode assembly, a battery cell, a battery and an electrical device, so as to improve the problem in the related art that the performance of the battery is affected because the size of the active material of the anode plate exceeds the size of the active material of the cathode plate and fails to meet the requirements.

[0005] According to one aspect of an embodiment of the present disclosure, an electrode assembly is provided, the electrode assembly including a cathode electrode sheet and an anode electrode sheet stacked with the cathode electrode sheet.

[0006] The cathode electrode sheet includes a cathode current collector, a cathode active material coating provided on the surface of the cathode current collector, and a first insulating material coating provided on one side of the cathode active material coating along the winding axis; the first insulating material coating includes a first end section located at an end of the first insulating material coating along the winding direction and a first middle section located in the middle of the first insulating material coating along the winding direction, wherein the size of the first end section along the winding axis is larger than the size of the first middle section; and / or

[0007] The anode electrode sheet includes an anode current collector, an anode active material coating provided on the surface of the anode current collector, and a second insulating material coating provided on one side of the anode active material coating along the winding axis; the second insulating material coating includes a second end section located at the end of the second insulating material coating along the winding direction and a second middle section located in the middle of the second insulating material coating along the winding direction, wherein the size of the second end section along the winding axis is smaller than the size of the second middle section.

[0008] This is beneficial to satisfying the requirement that the size of the active material of the anode plate exceeds that of the active material of the cathode plate, and improves the problem in related technologies that the performance of the battery is affected because the size of the active material of the anode plate exceeds that of the active material of the cathode plate and fails to meet the requirement.

[0009] In some embodiments,

[0010] The first insulating material coating comprises two first end sections respectively located at two ends of the cathode current collector in a winding direction, and the first middle section is located between the two first end sections; and / or

[0011] The second insulating material coating layer includes two second end segments respectively located at both ends of the cathode current collector in the winding direction, and the second middle segment is located between the two second end segments.

[0012] This is beneficial to ensuring that the size of the active material of the anode electrode sheet exceeds that of the active material of the cathode electrode sheet at both the beginning and the end of the electrode sheet.

[0013] In some embodiments,

[0014] The material of the first insulating material coating includes ceramic insulating material; and / or

[0015] The material of the second insulating material coating includes ceramic insulating material,

[0016] Ceramic insulation materials offer high-temperature resistance, maintaining insulation performance even when battery temperatures are too high. They also offer excellent corrosion resistance, preventing electrolyte corrosion and loss of insulation performance, which helps extend battery life. Furthermore, ceramic insulation materials offer excellent wear resistance, helping prevent failure during the electrode winding process.

[0017] In some embodiments,

[0018] The cathode active material coating comprises a third end segment located at an end of the cathode active material coating along the winding direction and a third middle segment located in the middle of the cathode active material coating along the winding direction, the third end segment being arranged opposite to the first end segment, and the third middle segment being arranged opposite to the first middle segment; and / or

[0019] The anode active material coating includes a fourth end segment located at an end of the anode active material coating along the winding direction and a fourth middle segment located in the middle of the anode active material coating along the winding direction, the fourth end segment is arranged opposite to the second end segment, and the fourth middle segment is arranged opposite to the second middle segment.

[0020] The width of the cathode active material coating and the anode active material layer is increased as much as possible to ensure the energy storage capacity of the electrode assembly.

[0021] In some embodiments,

[0022] The cathode current collector comprises a cathode current collector body and a cathode tab provided at one end of the cathode current collector body along the winding axis of the cathode current collector, and the first insulating material coating is provided at one end of the cathode current collector body close to the cathode tab in the winding axis; and / or

[0023] The anode current collector includes an anode current collector body and an anode tab provided at one end of the anode current collector body along the winding axis of the anode current collector. The second insulating material coating is provided at one end of the anode current collector body close to the anode tab in the winding axis.

[0024] In some embodiments,

[0025] The cathode current collector comprises a plurality of cathode tabs arranged along a winding direction, and one or two cathode tabs are provided between two ends of the first end section of the first insulating material coating along the winding direction; and / or

[0026] The anode current collector includes a plurality of anode tabs arranged along a winding direction, and one or two anode tabs are provided between the two ends of the second end section of the second insulating material coating along the winding direction.

[0027] The first end section or the second end section is set to be long enough to ensure that the active material of the anode electrode sheet exceeds the active material of the cathode electrode sheet at the end of the cathode electrode sheet that is prone to wrinkling.

[0028] In some embodiments,

[0029] The difference between the dimension of the first end section along the winding axis and the dimension of the middle section is L, wherein 0.1 mm ≤ L ≤ 0.9 mm; and / or

[0030] The difference between the size of the second end section along the winding axis and the size of the middle section is L1, where 0.1mm≤L1≤0.9mm,

[0031] The first end section or the second end section is set to be long enough to ensure that the active material of the anode electrode sheet exceeds the active material of the cathode electrode sheet at the end of the cathode electrode sheet that is prone to wrinkling.

[0032] In some embodiments,

[0033] The junction between the first end section and the first middle section has a sudden change in size and forms a transition step; and / or

[0034] The junction between the second end section and the second middle section has a sudden change in size and forms a transition step.

[0035] During the process of applying the insulating material coating, only the width of the coating tool needs to be changed at the junction of the first middle section and the first end section or the junction of the second middle section and the second end section, which is beneficial to reducing processing difficulty and improving processing efficiency.

[0036] In some embodiments,

[0037] The first insulating material coating further includes a first transition section provided between the first middle section and the first end section, wherein a dimension of the first transition section along the winding axis gradually decreases from the first end section to the first middle section; and / or

[0038] The second insulating material coating further includes a second transition section provided between the second middle section and the second end section, wherein the size of the second transition section along the winding axis gradually increases from the second end section to the second middle section.

[0039] The first transition section and the second transition section can gradually reduce the width of the active material of the cathode electrode and the active material of the anode electrode, which is conducive to ensuring that the active material of the anode electrode exceeds the size of the active material of the cathode electrode.

[0040] In some embodiments,

[0041] The length of the first end section is 0 to 200 mm; and / or

[0042] The length of the second end section is 0 to 200 mm,

[0043] The first end section or the second end section is set to be long enough to ensure that the active material of the anode electrode sheet exceeds the active material of the cathode electrode sheet at the end of the cathode electrode sheet that is prone to wrinkling.

[0044] In some embodiments, the cathode and anode plates are wound into a cylindrical shape.

[0045] The length of the first end section is from half a turn to two turns; and / or

[0046] The length of the second end section is half a circle to two circles,

[0047] The first end section or the second end section is set to be long enough to ensure that the active material of the anode electrode sheet exceeds the active material of the cathode electrode sheet at the end of the cathode electrode sheet that is prone to wrinkling.

[0048] In some embodiments, the size of the anode active material layer exceeding the cathode active material layer at the end of the winding direction is not less than the size of the anode active material layer exceeding the cathode active material layer in the middle of the winding direction, meeting the requirement that the active material of the anode electrode sheet exceeds the active material of the cathode electrode sheet to ensure the performance of the electrode assembly.

[0049] According to another aspect of the present application, a method for manufacturing the electrode assembly is also provided, the manufacturing method comprising:

[0050] Increase the size of the first insulating material coating at the end of the cathode current collector along the winding direction so that the size of the first end segment along the winding axial direction is larger than the size of the first middle segment along the winding axial direction; and / or reduce the size of the second insulating material coating at the end of the anode current collector along the winding direction so that the size of the second end segment along the winding axial direction is smaller than the size of the second middle segment along the winding axial direction.

[0051] Lengthening the size of the cathode electrode piece along the winding direction; and / or, lengthening the size of the cathode electrode piece along the winding direction.

[0052] According to another aspect of the present application, a battery cell is provided, comprising the above-mentioned cathode electrode.

[0053] According to another aspect of the present application, a battery is provided, comprising the above-mentioned cathode electrode.

[0054] According to another aspect of the present application, there is also provided an electrical device comprising the above-mentioned battery.

[0055] By applying the technical solution of the present application, the width of the first end section of the first insulating material coating located at the end of the cathode electrode sheet along the winding direction is larger, and correspondingly, the width of the cathode active material coating flush with the first end section in the winding direction is smaller; or, the width of the second end section of the second insulating material coating located at the end of the anode electrode sheet along the winding direction is smaller, and correspondingly, the width of the anode active material coating flush with the second end section in the winding direction is larger, and the difference between the width of the anode active material of the anode electrode sheet and the width of the cathode active material of the cathode electrode sheet at the end of the electrode assembly along the winding direction is increased. Therefore, even if wrinkles or a certain offset occurs at the end of the electrode sheet along the winding direction, the distance between the edge of the anode active material in the width direction and the edge of the cathode active material can still be guaranteed, that is, the anode active material of the anode electrode sheet exceeds the size of the cathode active material of the cathode electrode sheet, thereby improving the problem in the related art that the performance of the battery is affected because the size of the anode active material of the anode electrode sheet exceeds the size of the cathode active material of the cathode electrode sheet and fails to meet the requirements.

[0056] Other features and advantages of the present disclosure will become apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0058] FIG1 shows a schematic structural diagram of an electric device disclosed in some embodiments of the present application;

[0059] FIG2 shows a schematic diagram of the exploded structure of a battery disclosed in some embodiments of the present application;

[0060] FIG3 shows a schematic structural diagram of a battery cell disclosed in some embodiments of the present application; and

[0061] FIG4 shows a schematic structural diagram of winding electrode sheets into an electrode assembly disclosed in some embodiments of the present application;

[0062] FIG5 is a schematic structural diagram of a cathode electrode piece of an electrode assembly disclosed in some embodiments of the present application;

[0063] FIG6 shows a schematic structural diagram of a cathode electrode piece of an electrode assembly disclosed in some embodiments of the present application;

[0064] FIG7 is a schematic structural diagram showing a comparative example of an electrode assembly according to some embodiments of the present application;

[0065] FIG8 shows a schematic structural diagram of an electrode assembly disclosed in some embodiments of the present application;

[0066] FIG9 is a schematic diagram showing the principle of a wound electrode assembly disclosed in some embodiments of the present application;

[0067] FIG10 is a schematic structural diagram of a wound electrode assembly disclosed in some embodiments of the present application;

[0068] FIG11 shows an exploded view of a wound electrode assembly according to some embodiments of the present application;

[0069] FIG12 shows an exploded view of a wound electrode assembly according to some other embodiments of the present application;

[0070] FIG13 shows a schematic structural diagram of an anode electrode sheet of an electrode assembly disclosed in some embodiments of the present application. DETAILED DESCRIPTION

[0071] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present disclosure and its application or use. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0072] In the description of this application, it should be noted that, unless otherwise specified, "multiple" means more than two; the terms "upper", "lower", "left", "right", "inside", "outside", etc., indicating directions or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly perpendicular, but is within the allowable error range. "Parallel" is not strictly parallel, but is within the allowable error range.

[0073] The directional words appearing in the following description are all directions shown in the figures, and do not limit the specific structure of this application. In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0074] Further, " scope " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and selected lower limit and upper limit define the boundary of special scope. The scope that this mode limits can be to include end value or not include end value, and can be arbitrarily combined, and promptly any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 listed, and if the maximum range value 3,4 and 5 are listed, then the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, numerical range " ab " represents the abbreviation of any real number combination between a and b, and wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0075] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0076] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0077] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0078] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0079] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0080] Currently, market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0081] FIG1 shows a schematic structural diagram of an electric device that uses a battery as a power source; as shown in FIG1 , the electric device of this embodiment includes a vehicle 1000, which may be a pure electric vehicle, a hybrid electric vehicle, or an extended-range vehicle, etc. A battery pack 100 is provided inside the vehicle 1000, and the battery pack 100 may be provided at the bottom, head, or tail of the vehicle 1000. The battery pack 100 may be used to power the vehicle 1000, for example, the battery pack 100 may serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, and the controller 200 is used to control the battery pack 100 to power the motor 300, for example, for starting, navigating, and operating power requirements of the vehicle 1000 during driving.

[0082] In some embodiments of the present application, the battery pack 100 can serve not only as the operating power source of the vehicle 1000, but also as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0083] Please refer to Figure 2, which is an exploded view of a battery pack 100 provided in some embodiments of the present application. The battery pack 100 includes a case 110 and a battery module disposed in the case 110. The battery module includes a plurality of battery cells 120, and the battery cells 120 are accommodated in the case 110. The case 110 is used to provide a storage space for the battery cells 120, and the case 110 can adopt a variety of structures. In some embodiments, the case 110 may include a first portion 111 and a second portion 112, the first portion 111 and the second portion 112 covering each other, and the first portion 111 and the second portion 112 jointly define a storage space for accommodating the battery cells 120. The second portion 112 can be a hollow structure with one end open, and the first portion 111 can be a plate-like structure. The first portion 111 covers the open side of the second portion 112, so that the first portion 111 and the second portion 112 jointly define a storage space. The first portion 111 and the second portion 112 can also be hollow structures with one end open, with the open side of the first portion 111 covering the open side of the second portion 112. Of course, the box 110 formed by the first portion 111 and the second portion 112 can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0084] In the battery pack 100, there may be multiple battery cells 120, and the multiple battery cells 120 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 120. The multiple battery cells 120 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery pack 120 may be housed within the housing 110. Alternatively, the battery pack 100 may be constructed by first connecting multiple battery cells 120 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 110. The battery pack 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 120.

[0085] Each battery cell 120 may be a secondary battery or a primary battery, a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 120 may be cylindrical, flat, rectangular, or in other shapes.

[0086] Please refer to Figure 3, which is a schematic diagram of the exploded structure of a battery cell 120 provided in some embodiments of the present application. A battery cell 120 is the smallest unit that makes up the battery pack 100. As shown in Figure 3, a battery cell 120 includes an end cap 121, a housing 122, a cell assembly 123 (also known as an electrode assembly), and other functional components.

[0087] The end cap 121 is a component that covers the opening of the housing 122 to isolate the internal environment of the battery cell 120 from the external environment. The shape of the end cap 121 can be adapted to the shape of the housing 122 to fit the housing 122. Optionally, the end cap 121 can be made of a material with a certain degree of hardness and strength, such as an aluminum alloy. This prevents the end cap 121 from deforming under pressure or collision, providing the battery cell 120 with greater structural strength and improved safety. The end cap 121 can be provided with functional components such as electrode terminals 121a. The electrode terminals 121a can be used to electrically connect to the battery cell assembly 123 to transfer electrical energy to or from the battery cell 120. In some embodiments, the end cap 121 can also be provided with a pressure relief mechanism to release internal pressure when the internal pressure or temperature of the battery cell 120 reaches a threshold. The end cap 121 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, and plastic, and this is not particularly limited in this embodiment of the present application. In some embodiments, an insulating member may be provided inside the end cap 121 to isolate the electrical connection components in the housing 122 from the end cap 121 to reduce the risk of short circuit.

[0088] The housing 122 is a component used to cooperate with the end cap 121 to form the internal environment of the battery cell 120, wherein the formed internal environment can be used to accommodate the battery cell assembly 123, electrolyte, and other components. The housing 122 and the end cap 121 can be independent components. An opening can be provided on the housing 122, and the end cap 121 is closed at the opening to form the internal environment of the battery cell 120. Without limitation, the end cap 121 and the housing 122 can also be integrated. Specifically, the end cap 121 and the housing 122 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 122 needs to be encapsulated, the end cap 121 is closed over the housing 122. The housing 122 can have a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the housing 122 can be determined according to the specific shape and size of the battery cell assembly 123. The shell 122 can be made of various 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.

[0089] The cell assembly 123 is the component within the battery cell 100 where the electrochemical reaction occurs. The housing 122 may contain one or more cell assemblies 123. These cell assemblies 123 are primarily formed by winding or stacking electrode sheets, including positive and negative electrodes, with a separator typically positioned between them.

[0090] The electrode sheet mainly consists of a thin sheet of current collector and an active material coated on the current collector. The parts of the positive electrode sheet (cathode electrode sheet) and the negative electrode sheet (anode electrode sheet) with active materials constitute the main body of the battery cell assembly, and the parts of the positive electrode sheet and the negative electrode sheet without active materials each constitute the tab 123a. The positive electrode tab and the negative electrode tab can be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery pack 100, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tab 123a connects the electrode terminal to form a current loop.

[0091] Referring to Figure 4 , during the winding process of the cathode electrode sheet 10 and the anode electrode sheet 20 onto the winding needle 50, the cathode electrode sheet 10 and the anode electrode sheet 20 each move toward the winding needle 50, thereby being wound in layers on the winding needle 50 to form an electrode assembly. An insulating separator is also provided between the cathode electrode sheet 10 and the anode electrode sheet 20. The winding direction of the cathode electrode sheet 10 and the anode electrode sheet 20 is consistent with their length, and the width direction of the cathode electrode sheet 10 and the anode electrode sheet 20 is consistent with the winding axis.

[0092] After forming an electrode assembly, the cathode electrode sheet 10 and the anode electrode sheet 20 are each cut by a cutter 30. After the electrode sheets (including the cathode electrode sheet 10 and the anode electrode sheet 20) are cut, the electrode sheets of the wound electrode assembly remain taut due to the lack of tension, and the tail end of the electrode sheet of the electrode assembly is in a relaxed state. The leading end of the next electrode assembly to be wound also remains taut due to the lack of tension and is in a relaxed state. The cathode electrode sheet 10 and the anode electrode sheet 20 are each provided with a corresponding deflection correction roller 40 to ensure the axial position of the cathode electrode sheet 10 and the anode electrode sheet 20 along the winding needle 50.

[0093] In summary, during the winding process of the electrode assembly, both the trailing and leading ends of the electrode sheet are in a relaxed state. In this relaxed state, the electrode sheet may wrinkle or shift along the winding axis and the width of the electrode sheet, resulting in the anode active material of the anode electrode sheet exceeding the cathode active material of the cathode electrode sheet (overhang, abbreviated as OH), making it difficult to meet the predetermined requirements. In some embodiments, widening the width of the anode electrode sheet to ensure that the anode active material exceeds the cathode active material, will result in an increase in the size of the anode electrode sheet in the winding axis.

[0094] In order to improve the above-mentioned problems, this embodiment provides an electrode assembly, which includes a cathode electrode sheet 10 and an anode electrode sheet 20 stacked with the cathode electrode sheet 10. Referring to Figures 5 and 6, the cathode electrode sheet of this embodiment includes a cathode current collector 1, a cathode active material coating 2 and a first insulating material coating 3.

[0095] The first insulating material coating 3 is provided on one side of the cathode active material coating 2 along the winding axis. The first insulating material coating 3 includes a first end section 31 located at the end of the first insulating material coating 3 along the winding direction, and a first middle section 32 located in the middle of the first insulating material coating 3 along the winding direction. The first end section 31 is larger than the first middle section 32 along the winding axis.

[0096] The cathode active material coating 2 is provided on the surface of the cathode current collector 1. The first insulating material coating 3 is provided on the same surface of the cathode active material coating 2 as the cathode current collector 1 and is arranged side by side with the cathode active material coating 2 along the winding axis.

[0097] The cathode active material coating 2 includes a third end segment 21 located at the end of the active material coating 2 along the winding direction and a third middle segment 22 located in the middle of the cathode active material coating 2 along the winding direction. The third end segment 21 is arranged opposite to the first end segment 31, and the third middle segment 22 is arranged opposite to the first middle segment 32.

[0098] The third end section 21 is aligned with the first end section 31 in the winding direction and connected to the first end section 31 in the winding axis. The third middle section 22 is aligned with the first middle section 32 in the winding direction and connected to the first middle section 32 in the winding axis. In the first middle section 32, where the first insulating material coating 3 is narrower, the width of the cathode active material coating 2 is maximized to ensure the energy storage capacity of the electrode assembly.

[0099] The width of the first end section 31 of the first insulating material coating 3 located at the end of the cathode electrode 10 along the winding direction is relatively large. Correspondingly, the width of the third end section 21 of the cathode active material coating 2, which is flush with the first end section 31 of the first insulating material coating 3 in the winding direction on the cathode electrode 10, is relatively small. Even if wrinkles or a certain offset occurs at the end of the electrode along the winding direction, the distance between the edge of the anode active material in the width direction and the edge of the cathode active material can still be guaranteed. Therefore, it is conducive to meeting the size of the active material of the anode electrode exceeding the active material of the cathode electrode, and improves the problem in the related art that the performance of the battery is affected because the size of the active material of the anode electrode exceeding the active material of the cathode electrode does not meet the requirements.

[0100] In some embodiments, the first insulating material coating 3 includes two first end segments 31 located at two ends of the winding direction, and the first middle segment 32 is located between the two first end segments 31. The two ends of the cathode current collector 1 of the cathode electrode sheet 10 are respectively the beginning and the end of the electrode assembly winding process. The two first end segments 31 of the first insulating material coating 3 located at two ends of the winding direction are both relatively wide, which is conducive to ensuring that the active material of the anode electrode sheet exceeds the active material of the cathode electrode sheet at both the beginning and the end of the electrode sheet.

[0101] In some embodiments, the first insulating coating 3 is made of a ceramic insulating material. In some embodiments, the ceramic insulating material includes AT11. Ceramic insulating materials have high-temperature resistance, maintaining insulation performance when the battery temperature is too high. They also have excellent corrosion resistance, preventing loss of insulation performance due to electrolyte corrosion, which helps improve battery life. Furthermore, ceramic insulating materials have excellent wear resistance, which helps prevent failure during the electrode winding process.

[0102] In some embodiments, the cathode active material coating 2 and the first insulating material coating 3 are sequentially connected in the winding axis direction. The ends of the cathode active material coating 2 are connected to the first end section 31, and the middle of the cathode active material coating 2 is connected to the first middle section 32. The width of the middle portion of the cathode active material coating 2 is greater than the width of the ends of the cathode active material coating 2. The length of the middle portion of the cathode active material coating 2 is the same as the length of the first middle section 32 where the width of the first insulating material coating 3 is narrower. In the first middle section 32 where the width of the first insulating material coating 3 is narrower, the width of the cathode active material coating 2 is increased as much as possible to ensure the energy storage capacity of the electrode assembly.

[0103] In some embodiments, the cathode current collector 1 includes a cathode current collector body 11 and a cathode tab 12 provided at one end of the cathode current collector body 11 along the winding axis, and the first insulating material coating 3 is provided at one end of the cathode current collector body 11 close to the cathode tab 12 in the winding axis.

[0104] In some embodiments, the cathode current collector 1 includes a plurality of cathode tabs 12 arranged along the winding direction, and a first end section 31 of the first insulating material coating 3 has one or two cathode tabs 12 between both ends along the winding direction. The first end section 31 is set to a sufficient length to ensure that the size of the active material of the anode plate exceeds the active material of the cathode plate at the end of the cathode plate that is prone to wrinkling.

[0105] In some embodiments, the length of the first end segment 31 is 0 to 200 mm. In some embodiments, the length of the first end segment 31 is 5 to 20 mm. Specifically, the length of the first end segment 31 is 10 mm. The first end segment 31 is set to be long enough to ensure that the active material of the anode electrode sheet exceeds the active material of the cathode electrode sheet at the end of the cathode electrode sheet that is prone to wrinkling.

[0106] In some embodiments, the difference between the dimension of the first end segment 31 along the winding axis and the dimension of the first middle segment 32 is L, where 0.1 mm ≤ L ≤ 0.9 mm. In some embodiments, the difference L is 0.5 mm. The first end segment 31 is configured to have a sufficient width to ensure that the active material of the anode electrode sheet exceeds the active material of the cathode electrode sheet at the end of the cathode electrode sheet, which is prone to wrinkling.

[0107] Referring to Figure 9 , during the process of forming an electrode assembly, as the cathode electrode sheet 10, anode electrode sheet 20, and separator 60 are respectively wound onto the winding needle 50, the cathode electrode sheet 10, anode electrode sheet 20, and separator 60 are respectively moved toward the winding needle 50, so that the cathode electrode sheet 10, separator 60, and anode electrode sheet 20 are wound on the winding needle 50 in a stacked manner to form the electrode assembly. A separator made of an insulating material is also provided between the cathode electrode sheet 10 and the anode electrode sheet 20.

[0108] FIG10 is a schematic diagram of the structure of the electrode assembly after winding, and FIG11 is a decomposition diagram of the electrode assembly after forming. As shown in FIG10 and FIG11, the size of the junction between the first middle section 32 and the first end section 31 changes suddenly and forms a transition step 33. The angle between the side of the first end section 31 adjacent to the first middle section 32 along the winding axis and the side of the first middle section 32 along the winding direction is a right angle, see FIG5 and FIG10 to 11. In the process of applying the first insulating material coating 3, it is only necessary to change the width of the coating tool at the junction of the first middle section 32 and the first end section 31, which is conducive to reducing the difficulty of processing and improving processing efficiency.

[0109] Figure 12 shows a decomposition diagram of the electrode assembly of some other embodiments. In some other embodiments, the first insulating material coating 3 also includes a first transition section 34 arranged between the middle section 31 and the first end section 32, and the width of the first transition section 34 gradually decreases from the first end section 32 to the middle section 31.

[0110] The first transition section 34 can gradually reduce the width of the active material of the cathode electrode piece and the active material of the anode electrode piece, which is beneficial to ensure that the active material of the anode electrode piece exceeds the size of the active material of the cathode electrode piece.

[0111] According to another aspect of the present disclosure, a method for manufacturing the electrode assembly is also provided, the manufacturing method comprising:

[0112] Method for manufacturing a cathode electrode sheet: increasing the size of the first insulating material coating 3 located at the end of the cathode current collector 1 along the winding direction so that the size of the first end section 31 along the winding axis of the cathode current collector 1 is larger than the size of the first middle section 32 along the winding axis; lengthening the length of the cathode electrode sheet 10 to maintain or increase the energy storage capacity of the electrode assembly, compensating for the loss of energy storage capacity due to the wider insulating layer at the end of the anode electrode sheet.

[0113] Method for manufacturing an anode electrode sheet: reducing the size of the second insulating material coating 6 located at the end of the anode current collector 4 along the winding direction so that the size of the second end segment 61 along the winding axis is smaller than the size of the second middle segment 62 along the winding axis; the size of the cathode electrode sheet 10 along the winding direction is reduced to increase the energy storage capacity of the electrode assembly.

[0114] FIG7 shows a schematic structural diagram of an electrode assembly according to a comparative example of the present application. In this comparative example, the end of the first insulating material coating 3 of the cathode electrode of the electrode assembly is widened to form the aforementioned first end section 31. In this comparative example, the lengths of the cathode electrode 10 and the anode electrode 20 of the electrode assembly are both lengthened. In the semicircular shape formed by winding the electrode pieces at one end of the electrode assembly, a section of the cathode electrode 10 near its tail end is one-quarter of the arc of the aforementioned semicircle. A section of the anode electrode near its tail end is one-half of the arc of the aforementioned semicircle.

[0115] Because the first end section 31 of the first insulating material coating 3 of the cathode electrode sheet is widened, the end of the cathode active material coating 2 is narrowed. To address the resulting loss in electrode assembly capacity, the length of the cathode electrode sheet 10 is increased. Referring to FIG8 , the increased length of the cathode electrode sheet 10 near its tail end is half the arc of the aforementioned semicircle. The length of the anode electrode sheet near its tail end is three-quarters the arc of the aforementioned semicircle.

[0116] The electrode assembly includes the cathode electrode sheet 10 , an anode electrode sheet 20 stacked on the cathode electrode sheet 10 , and an insulating separator 60 provided between the cathode electrode sheet 10 and the anode electrode sheet 20 .

[0117] In some embodiments, the cathode electrode sheet 10, anode electrode sheet 20, and insulating separator 60 are wound into a cylindrical shape, and the length of the first end segment 31 is the length of half a turn to two turns. A full turn is defined as winding the electrode sheet to the same angle as the starting point of the winding in the circumferential direction of the electrode assembly. In other words, a full turn extends 360 degrees in the circumferential direction of the electrode assembly, and a half turn extends 180 degrees in the circumferential direction of the electrode assembly. In some embodiments, the length of the first end segment 31 of the first insulating material coating 3 is the length of one and a half turns. The electrode sheet is bent twice for each full turn, and one and a half turns is equivalent to three folds.

[0118] In this embodiment, a first end section 31 having a larger dimension along the winding axis is provided at the tail end or the head end of the first insulating material coating 3 of the cathode electrode 10 along the winding direction of the cathode current collector 1. The difference L between the dimension along the winding axis of the first end section 31 and the dimension of the first middle section 32 is 0.5±0.4 mm. Therefore, when the head end or the tail end of the electrode is in a relaxed state, the dimension of the active material of the anode electrode sheet exceeds the dimension of the active material of the cathode electrode sheet.

[0119] Furthermore, the cathode active material coating 2 at the leading and trailing ends of the cathode electrode piece is 0.5±0.4mm smaller in the winding axis than the middle portion. To maintain the capacity of the electrode assembly, the length of the cathode electrode piece of the electrode assembly is increased, and the section of the cathode electrode piece 10 near its trailing end is extended from one-quarter of the arc of the aforementioned semicircle to one-half. High-power X-ray inspection equipment can effectively detect if the active material of the anode electrode piece at the trailing end of the electrode piece exceeds the size of the active material of the cathode electrode piece, preventing missed inspections.

[0120] Figure 13 shows a schematic structural diagram of the anode electrode sheet of the electrode assembly of some embodiments of the present application. As shown in Figure 13, the anode electrode sheet 20 includes an anode current collector 4, an anode active material coating 5 provided on the surface of the anode current collector 4, and a second insulating material coating 6 provided on one side of the anode active material coating 5 along the winding axis; the second insulating material coating 6 includes a second end segment 61 located at the end of the second insulating material coating 6 along the winding direction and a second middle segment 62 located in the middle of the second insulating material coating 6 along the winding direction, wherein the size of the second end segment 61 along the winding axis is smaller than the size of the second middle segment 62.

[0121] The width of the second end section 61 of the second insulating material coating 6 located at the end of the anode electrode sheet along the winding direction is smaller, and correspondingly, the width of the anode active material coating flush with the second end section 61 in the winding direction is larger, and the difference between the width of the anode active material of the anode electrode sheet at the end of the electrode assembly along the winding direction and the width of the cathode active material of the cathode electrode sheet 10 increases. Therefore, even if wrinkles or a certain offset occurs at the end of the electrode sheet along the winding direction, the distance between the edge of the anode active material in the width direction and the edge of the cathode active material can still be guaranteed, that is, the anode active material of the anode electrode sheet 20 exceeds the size of the cathode active material of the cathode electrode sheet, which improves the problem in the related art that the performance of the battery is affected because the size of the anode active material of the anode electrode sheet 20 exceeds the size of the cathode active material of the cathode electrode sheet and fails to meet the requirements.

[0122] The size of the anode active material layer 5 exceeding the cathode active material layer 2 at the end of the winding direction is not less than the size of the anode active material layer 5 exceeding the cathode active material layer 2 in the middle of the winding direction, which meets the requirement that the active material of the anode electrode sheet exceeds the active material of the cathode electrode sheet to ensure the performance of the electrode assembly.

[0123] The second insulating material coating 6 includes two second end segments 61 located at either end of the cathode current collector 1 in the winding direction, and a second middle segment 62 located between the two second end segments 61. The two ends of the anode current collector 1 of the anode plate 20 are the beginning and end of the winding process of the electrode assembly, respectively. The two second end segments 61 of the second insulating material coating 6 located at either end of the winding direction are both relatively wide, thereby facilitating the size of the anode plate's active material exceeding that of the cathode plate's active material at both the beginning and end of the plate.

[0124] In some embodiments, the second insulating coating 6 is made of a ceramic insulating material. In some embodiments, the ceramic insulating material includes AT11. Ceramic insulating materials have high-temperature resistance, maintaining insulation performance when the battery temperature is too high. They also have excellent corrosion resistance, preventing electrolyte corrosion and loss of insulation performance, which helps improve battery life. Furthermore, ceramic insulating materials have excellent wear resistance, which helps prevent failure during the electrode winding process.

[0125] The anode active material coating 5 includes a fourth end segment 51 located at the end of the anode active material coating 5 along the winding direction and a fourth middle segment 52 located in the middle of the anode active material coating 5 along the winding direction. The fourth end segment 51 is arranged opposite to the second end segment 61, and the fourth middle segment 52 is arranged opposite to the second middle segment 62.

[0126] The anode active material coating 5 and the second insulating material coating 6 are connected in sequence in the winding axis direction. The ends of the anode active material coating 5 are connected to the second end section 61, and the middle of the anode active material coating 5 is connected to the second middle section 62. The width of the middle portion of the anode active material coating 5 is greater than the width of the ends of the anode active material coating 5. The length of the middle portion of the anode active material coating 5 is the same as the length of the second middle section 62, where the width of the second insulating material coating 6 is narrower. In the second middle section 62, where the width of the second insulating material coating 6 is narrower, the width of the anode active material coating 5 is increased as much as possible to ensure the energy storage capacity of the electrode assembly.

[0127] The anode current collector 4 includes an anode current collector body 41 and an anode tab 42 provided at one end of the anode current collector body 41 along the winding axis of the anode current collector 4 . The second insulating material coating 6 is provided at one end of the anode current collector body 41 close to the anode tab 42 in the winding axis.

[0128] The anode current collector 4 includes a plurality of anode tabs 42 arranged along a winding direction. The second end section 61 of the second insulating material coating 6 has one or two anode tabs 42 between both ends along the winding direction.

[0129] In some embodiments, the anode current collector 4 includes a plurality of cathode tabs 42 arranged along the winding direction, and the second end segment 61 of the second insulating material coating 6 has one or two anode tabs 42 between both ends along the winding direction. The second end segment 61 is set to a sufficient length to ensure that the size of the active material of the anode plate exceeds the active material of the cathode plate at the end of the cathode plate that is prone to wrinkling.

[0130] The difference between the dimension of the second end segment 61 along the winding axis and the dimension of the middle segment 32 is L1, where 0.1 mm ≤ L1 ≤ 0.9 mm. In some embodiments, the difference L1 is 0.5 mm. The second end segment 61 is configured to be sufficiently wide to ensure that the active material of the anode electrode sheet exceeds the active material of the cathode electrode sheet at the end of the cathode electrode sheet, which is prone to wrinkling.

[0131] The junction of the second end section 61 and the second middle section 62 has a sudden change in size, forming a transition step 63. During the application of the second insulating material coating 6, only the width of the coating tool needs to be changed at the junction of the second middle section 62 and the second end section 61, which helps to reduce processing difficulty and improve processing efficiency.

[0132] The second insulating material coating 6 further includes a second transition section provided between the second middle section 62 and the second end section 61. The dimension of the second transition section along the winding axis gradually increases from the second end section 61 to the second middle section 62. The second transition section can gradually reduce the width of the active material of the cathode electrode piece and the active material of the anode electrode piece, which helps to ensure that the active material of the anode electrode piece exceeds the active material of the cathode electrode piece.

[0133] The length of the second end segment 61 is 0 to 200 mm. In some embodiments, the length of the second end segment 61 is 5 to 20 mm. Specifically, the length of the second end segment 61 is 10 mm. The second end segment 61 is set to be long enough to ensure that the active material of the anode electrode sheet exceeds the active material of the cathode electrode sheet at the end of the cathode electrode sheet that is prone to wrinkling.

[0134] The second end section 61 has a length of half a circle to two circles and is wide enough to ensure that the active material of the anode plate exceeds the active material of the cathode plate at the end of the easily wrinkled cathode plate.

[0135] The above are merely exemplary embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the scope of protection of the present disclosure.

Claims

1. An electrode assembly comprising a cathode electrode sheet (10) and an anode electrode sheet (20) stacked with the cathode electrode sheet (10), The cathode electrode (10) comprises a cathode current collector (1), a cathode active material coating (2) provided on the surface of the cathode current collector (1), and a first insulating material coating (3) provided on one side of the cathode active material coating (2) along the winding axis; the first insulating material coating (3) comprises a first end section (31) located at the end of the first insulating material coating (3) along the winding direction and a first middle section (32) located in the middle of the first insulating material coating (3) along the winding direction, wherein the size of the first end section (31) along the winding axis is larger than the size of the first middle section (32); and / or The anode electrode sheet (20) comprises an anode current collector (4), an anode active material coating (5) provided on the surface of the anode current collector (4), and a second insulating material coating (6) provided on one side of the anode active material coating (5) along the winding axis; the second insulating material coating (6) comprises a second end section (61) located at the end of the second insulating material coating (6) along the winding direction and a second middle section (62) located in the middle of the second insulating material coating (6) along the winding direction, wherein the size of the second end section (61) along the winding axis is smaller than the size of the second middle section (62).

2. The electrode assembly according to claim 1, wherein The first insulating material coating (3) comprises two first end sections (31) respectively located at two ends of the winding direction of the cathode current collector (1), and the first middle section (32) is located between the two first end sections (31); and / or The second insulating material coating (6) comprises two second end sections (61) respectively located at two ends of the winding direction of the cathode current collector (1), and the second middle section (62) is located between the two second end sections (61).

3. The electrode assembly according to claim 1 or 2, wherein: The material of the first insulating material coating (3) includes ceramic insulating material; and / or The material of the second insulating material coating (6) includes ceramic insulating material.

4. The electrode assembly according to any one of claims 1 to 3, wherein: The cathode active material coating (2) comprises a third end section (21) located at the end of the cathode active material coating (2) along the winding direction and a third middle section (22) located at the middle of the cathode active material coating (2) along the winding direction, the third end section (21) being arranged opposite to the first end section (31), and the third middle section (22) being arranged opposite to the first middle section (32); and / or The anode active material coating (5) comprises a fourth end section (51) located at the end of the anode active material coating (5) along the winding direction and a fourth middle section (52) located in the middle of the anode active material coating (5) along the winding direction, wherein the fourth end section (51) is arranged opposite to the second end section (61), and the fourth middle section (52) is arranged opposite to the second middle section (62).

5. The electrode assembly according to any one of claims 1 to 4, wherein The cathode current collector (1) comprises a cathode current collector body (11) and a cathode tab (12) provided at one end of the cathode current collector body (11) along the winding axis of the cathode current collector (1), and the first insulating material coating (3) is provided at one end of the cathode current collector body (11) close to the cathode tab (12) in the winding axis; and / or The anode current collector (4) comprises an anode current collector body (41) and an anode tab (42) provided at one end of the anode current collector body (41) along the winding axis of the anode current collector (4); the second insulating material coating (6) is provided at one end of the anode current collector body (41) close to the anode tab (42) in the winding axis.

6. The electrode assembly according to claim 5, wherein: The cathode current collector (1) comprises a plurality of cathode tabs (12) arranged along the winding direction, and a first end section (31) of the first insulating material coating (3) has one or two cathode tabs (12) between both ends along the winding direction; and / or The anode current collector (4) comprises a plurality of anode tabs (42) arranged along the winding direction, and the second end section (61) of the second insulating material coating (6) has one or two anode tabs (42) between both ends along the winding direction.

7. The electrode assembly according to any one of claims 1 to 6, wherein: The difference between the dimension of the first end section (31) along the winding axis and the dimension of the middle section (32) is L, wherein 0.1 mm ≤ L ≤ 0.9 mm; and / or The difference between the size of the second end section (61) along the winding axis and the size of the middle section (32) is L1, wherein 0.1 mm ≤ L1 ≤ 0.9 mm.

8. The electrode assembly according to any one of claims 1 to 7, wherein: The junction between the first end section (31) and the first middle section (32) has a sudden change in size and forms a transition step (33); and / or The junction between the second end section (61) and the second middle section (62) has a sudden change in size and forms a transition step (63).

9. The electrode assembly according to any one of claims 1 to 8, wherein: The first insulating material coating (3) further comprises a first transition section (34) provided between the first middle section (32) and the first end section (31), wherein a dimension of the first transition section (34) along the winding axis gradually decreases from the first end section (31) to the first middle section (32); and / or The second insulating material coating (6) further includes a second transition section arranged between the second middle section (62) and the second end section (61), and the size of the second transition section along the winding axis gradually increases from the second end section (61) to the second middle section (62).

10. The electrode assembly according to any one of claims 1 to 9, wherein: The length of the first end section (31) is 0 to 200 mm; and / or The length of the second end section (61) is 0 to 200 mm.

11. The electrode assembly according to any one of claims 1 to 10, wherein the cathode electrode sheet (10) and the anode electrode sheet (20) are wound into a cylindrical shape. The length of the first end section (31) is from half a circle to two circles; and / or The length of the second end section (61) is from half a circle to two circles.

12. An electrode assembly according to any one of claims 1 to 11, wherein the size of the anode active material layer (5) exceeding the cathode active material layer (2) at the end of the winding direction is not less than the size of the anode active material layer (5) exceeding the cathode active material layer (2) in the middle of the winding direction.

13. A method for manufacturing the electrode assembly according to any one of claims 1 to 12, comprising: Enlarging the size of the first insulating material coating (3) at the end of the cathode current collector (1) along the winding direction so that the size of the first end section (31) along the winding axis is larger than the size of the first middle section (32) along the winding axis; and / or reducing the size of the second insulating material coating (6) at the end of the anode current collector (4) along the winding direction so that the size of the second end section (61) along the winding axis is smaller than the size of the second middle section (62) along the winding axis; The dimension of the cathode pole piece (10) along the winding direction is lengthened; and / or the dimension of the cathode pole piece (10) along the winding direction is lengthened. 14 . A battery cell comprising the electrode assembly according to claim 1 . 15 . A battery comprising the electrode assembly according to claim 1 .

16. An electrical device comprising the battery according to claim 15.

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