Battery electrode sheet, secondary battery and electric device

Abstract

A battery electrode sheet (30), a secondary battery and an electric device. The battery electrode sheet (30) comprises: an electrode sheet body (31), which has a length direction (L) and a width direction (W) perpendicular to the length direction; and N tabs (32), which are spaced apart in a region between a winding start end of and a winding termination end of the electrode sheet body (31), and comprise a first tab to an Nth tab, wherein each tab (32) is connected to one side of the electrode sheet body (31) in the width direction (W) and has a width size in the length direction (L) of the electrode sheet body (31), and the width sizes of the nth tab to the (n+k)th tab are greater than the width sizes of the remaining tabs, N being a positive integer greater than 3, n+k being less than N, and both n and k being positive integers greater than 1. In this way, the negative impact of misalignment of the tabs (32) can be reduced.

Description

Battery poles, secondary batteries and electrical equipment

[0001] This application claims priority to the prior application with application number 202410184081.9 filed with the State Intellectual Property Office of China on February 19, 2024, entitled “Battery Electrode, Secondary Battery and Electrical Equipment”. The contents of the above-mentioned prior application are incorporated into this text by introduction. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to a battery electrode, a secondary battery, and an electrical device. Background Art

[0003] With the continuous development of fast-charging technology, multi-tab battery cells, which can better support and meet higher charging power requirements, have begun to be widely valued and used. However, due to practical factors such as electrode thickness and uneven active material coating, multi-tab battery cells inevitably experience tab misalignment.

[0004] Tab misalignment can seriously affect the use and safety performance of the battery, causing difficulties in inserting the battery cell into the shell and failure to pass the battery cell drop test.

[0005] Application Contents

[0006] The purpose of this application is to provide a battery electrode, a wound battery cell, a secondary battery and an electrical device, aiming to reduce the adverse effects caused by the misalignment of the tabs of a multi-tab battery cell.

[0007] According to a first aspect of the present application, a battery electrode is provided. The battery electrode comprises: a electrode body having a length direction and a width direction perpendicular to the length direction; N electrode tabs spaced apart in a region between a winding start end and a winding end end of the electrode body; the N electrode tabs comprise first to Nth electrode tabs, the first to Nth electrode tabs being arranged along a direction from the winding start end to the winding end end; wherein each electrode tab is connected to one side of the electrode body in a width direction and has a width dimension in the length direction of the electrode body; the width dimensions of the nth to n+kth electrode tabs are greater than the width dimensions of the remaining electrode tabs; N is a positive integer greater than 3, and n+k is less than N; and n and k are both positive integers greater than 1.

[0008] The battery electrode sheet involved in this application has tabs with different widths along the winding direction of the battery electrode sheet. The tabs located at the center of the winding, which are less prone to misalignment, are set to a larger width, while the tabs located at the edges of the winding, which are more prone to misalignment, are set to a smaller width. This allows tabs with different widths to adapt to the misalignment characteristics of the tabs during the winding process of the battery electrode sheet into a battery cell, providing a large amount of tab misalignment redundancy, ensuring sufficient overlap between multiple tabs, and reducing the impact of tab misalignment.

[0009] In one or more / optional embodiments above, the N pole tabs are evenly divided into the following three pole tab groups: a first pole tab group close to the starting end of the winding; a second pole tab group close to the ending end of the winding; and a third pole tab group located between the first pole tab group and the second pole tab group: wherein the average width dimension of the first pole tab group is smaller than that of the third pole tab group, and the average width dimension of the second pole tab group is smaller than that of the third pole tab group.

[0010] In one or more / optional embodiments above, the difference between the average width dimensions of the first tab group and the third tab group is between 5 mm and 15 mm; and / or the difference between the average width dimensions of the third tab group and the second tab group is between 5 mm and 15 mm.

[0011] The average width difference of 5-15 mm in this application is an optimal range for reducing the negative impact of tab misalignment. Within this range, lithium-ion batteries have higher safety and better tolerance and resistance to impact.

[0012] In one or more / optional embodiments above, the difference between the average width dimensions of the first tab group and the third tab group is between 8 mm and 10 mm; and / or the difference between the average width dimensions of the third tab group and the second tab group is between 8 mm and 10 mm.

[0013] When the flat width dimension difference involved in this application is in the range of 8mm to 10mm, it is a numerical range that can effectively reduce the negative impact of tab misalignment. Within this numerical range, the charge and discharge performance of the lithium-ion battery is at the platform peak.

[0014] In one or more / optional embodiments above, the width of each tab in the first tab group is between 25 mm and 40 mm; the width of each tab in the second tab group is between 25 mm and 40 mm; and the width of each tab in the third tab group is between 35 mm and 50 mm.

[0015] When the average width of the first and second tab groups involved in this application is 25-40 mm and the average width of the third tab group is 35-50 mm, the negative impact of tab misalignment can be effectively reduced. Within this numerical range, the lithium-ion battery has better charge and discharge performance.

[0016] In one or more / optional embodiments above, the pole piece body also has an extension portion extending along the width direction; the extension portion has: a first end connected to the pole piece body and a second end connected to the pole ear; wherein the width dimension of the first end in the length direction of the pole piece body is greater than that of the second end.

[0017] The extension portion of this application is configured such that the width of the first end is greater than the width of the second end. This, on the one hand, prevents the connection between the tab and the pole piece body from being too sharp, thereby reducing the risk of puncturing the separator. On the other hand, it also increases the width of the connection between the tab and the pole piece body, thereby preventing the connection from cracking or unnecessary deformation during the winding process, and better improving the problem of tab misalignment.

[0018] In one or more / optional embodiments above, the difference between the width dimensions of the first end and the second end of the extension portion is between 2-6 mm.

[0019] When the width difference between the first end and the second end involved in the present application is 2.0 mm to 6.0 mm, the short-circuit safety performance of the lithium-ion battery can be ensured while avoiding the problem of greater difficulty in processing.

[0020] In one or more / optional embodiments above, the surface density of the active material coated on the extension portion is 60-100 g / m2.

[0021] When the surface density of the active material involved in this application is in the range of 60g / m2 to 100g / m2, it can fully improve the charge and discharge performance of the lithium-ion battery while ensuring that the short-circuit safety performance of the lithium-ion battery sample is not significantly weakened. This is a relatively ideal numerical range.

[0022] In one or more / optional embodiments above, the connection portion between the pole tab and the pole piece body is configured as an arc chamfer.

[0023] The arc chamfer structural design involved in this application can, on the one hand, help enhance the supporting effect of the connection between the tab and the pole piece on the tab, thereby reducing the negative impact of tab misalignment; on the other hand, it can also make the transition between the tab and the pole piece body more natural and smooth, thereby reducing the local concentration of current.

[0024] In one or more / optional embodiments above, the angle of the arc chamfer ranges from 95° to 150°.

[0025] The preferred angle range for the arc chamfer in this application is 95 to 150 degrees. Within this angle range, as the R angle increases, the transition between the tab and the pole piece body becomes more natural, reducing the local concentration of current at the tab and pole piece connection and the resulting conduction problems. This improves the charge and discharge performance of the lithium-ion battery while avoiding a significant reduction in the energy density of the lithium-ion battery, achieving a balance between the two.

[0026] In one or more / optional embodiments above, the angle range of the arc chamfer is 120° to 130°.

[0027] When the angle range of the arc chamfer involved in this application is controlled within 120° to 130°, the charge and discharge performance of the lithium-ion battery can be at the platform peak while avoiding a significant reduction in the energy density of the lithium-ion battery sample, which is an optimal angle range.

[0028] According to a second aspect of the present application, a secondary battery is provided. The secondary battery comprises: an electrode assembly formed by winding anode and cathode electrodes spaced apart; a separator is provided between the electrode assemblies; wherein the cathode and / or anode electrodes are the battery electrodes described above.

[0029] According to a third aspect of the present application, an electric device is provided, which includes the secondary battery described above.

[0030] Additional aspects and advantages of the embodiments of the present application will be described, shown, or explained in part in the following description through implementation of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] To more clearly illustrate the specific embodiments of this application or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0032] FIG1 shows a schematic structural diagram of a wound battery cell provided in one embodiment of the present application;

[0033] FIG2 shows a top view of a wound battery cell provided in one embodiment of the present application;

[0034] FIG3 shows a top view of a wound battery cell provided by another embodiment of the present application;

[0035] FIG4 shows a schematic diagram of a battery electrode provided in one embodiment of the present application;

[0036] FIG5 is a flow chart showing a process for preparing a battery electrode sheet according to one embodiment of the present application;

[0037] FIG6 shows a schematic diagram of a battery electrode provided by another embodiment of the present application;

[0038] FIG. 7 shows a partial schematic diagram of region G in FIG. 6 .

[0039] 10: anode tab; 20: cathode tab;

[0040] 30: battery electrode; 31: electrode body; 32: electrode tab; 33: extension; 33a: first end of the extension; 33b: second end of the extension;

[0041] L: length direction; W: width direction; X: thickness direction of the electrode assembly; Ori: winding start end; Des: winding end end; R: arc chamfer. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0043] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0044] In the description of this application, it should be noted that, unless otherwise specified or limited, the terms "mounted" and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0045] The terms "upper", "lower", "top", "bottom" and the like used below indicate directions or positional relationships. The terms "vertical", "horizontal", "left", "right", "inner", "outer" and similar expressions used in this specification are for illustrative purposes only.

[0046] The technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0047] A "wound cell" is a compact electrode assembly structure that is formed by winding multiple layers of alternating anode and cathode sheets, with separators located between them.

[0048] The electrode assembly formed after winding can be formed into different shapes according to actual needs, such as cylindrical, square, soft-pack, etc. Its specific shape depends on the application requirements and is not specifically limited here. The "square" winding structure is used as an example in the drawings of the embodiment of this application.

[0049] Furthermore, the wound battery cell can be placed in a housing of suitable size, and after steps such as setting connecting components for transmitting electrical energy and injecting electrolyte, a secondary battery with the ability to store and release electrical energy can be manufactured.

[0050] The secondary battery can be widely used in various electronic devices, such as mobile phones, laptops, electric vehicles, and drones, to provide the power required for these electronic devices to operate. Furthermore, the secondary battery can also be connected to an energy source, drawing power from the energy source and storing it. For example, the energy source can be mains electricity or a storage capacitor.

[0051] During the charge and discharge process of these secondary batteries, the anode releases positive ions, and the cathode releases negative ions. These ions can move within the electrolyte, transferring charge through an external circuit to complete the charge and discharge process. This diffusion and migration of ions allows the wound cell to provide continuous power output.

[0052] Figure 1 is a schematic diagram of a wound battery cell provided in an embodiment of the present application. To increase the connection points of the electrode sheets or the contact area for current output, thereby improving the charge and discharge performance of the battery, as shown in Figure 1, multiple anode tabs 10 can be provided on the anode electrode sheet. Multiple cathode tabs 20 can also be provided on the cathode electrode sheet. As a result, current can be output from multiple anode tabs / cathode tabs to the external circuit, thereby effectively improving the current transmission capacity and uniformity, while reducing the risk of current density and heat concentration.

[0053] Continuing with Figure 1, ideally, in the wound electrode assembly, the multiple anode tabs 10 or cathode tabs 20 should be aligned as closely as possible in the thickness direction X of the wound cell, with the degree of misalignment between them strictly controlled. For simplicity, the term "misalignment" will be used below to refer to the degree of misalignment between tabs.

[0054] Typically, the amount of tab misalignment is tightly controlled by adjusting and controlling the spacing between tabs. However, due to factors such as design or processing errors (deviations in the size, position, or shape of the pole piece or tab), material differences (differences in size, shape, or strength), and uneven tension applied during the winding process, different tabs will always be stretched to varying degrees.

[0055] This unpredictable stretching can cause the actual position of the tabs after winding to differ from the ideal position. If the difference is too significant, the tabs will be misaligned and cannot be properly aligned.

[0056] In this application, for simplicity of description, the term "tab misalignment" is used to indicate a situation where the misalignment amount of the tab exceeds the design allowable margin.

[0057] Tab misalignment can negatively impact battery performance and safety. For example, it can lead to poor contact between tabs and stress concentration within the battery, potentially causing damage or failure. Therefore, minimizing misalignment is a key goal for improving the performance and safety of secondary batteries.

[0058] While implementing this application, the applicant discovered that during the winding process of the pole sheet, the position deviation of the pole lugs located at different positions of the pole sheet varies. Generally speaking, the position deviation of the pole lugs located in the middle area of ​​the pole sheet (for example, the pole lugs 12 and 13 shown in Figure 1) is significantly lower than that of the pole lugs located on the sides of the pole sheet (for example, the pole lugs 11, 14, and 15 shown in Figure 1).

[0059] Therefore, by setting the pole tabs located in the middle area of ​​the pole piece to have a larger width dimension and setting the pole tabs located in the area on both sides of the pole piece to have a smaller width dimension, the above-mentioned characteristics of different degrees of position deviation can be fully utilized, so that the multiple pole tabs in the wound battery cell are less likely to be misaligned, thereby reducing the amount of misalignment.

[0060] The principle of reducing misalignment described above is described in detail below, with reference to the schematic diagram shown in Figure 2. For example, tabs 11 through 15 employ the aforementioned inventive concept of varying widths. Tabs 12 and 13 in the center region have larger widths, while tabs 11, 14, and 15 in the side regions have smaller widths. In contrast, tabs 21 through 25 utilize a conventional configuration of uniform widths.

[0061] As shown in Figure 2, when tabs 12 and 13 have larger widths, the coverage area A1 they provide is larger than the coverage area A2 provided by tabs 22 and 23. Therefore, when the positional deviation B is the same, the portion of tabs 11, 14, and 15 protruding from the coverage area A1 is significantly smaller than the portion of tabs 21, 24, and 25 protruding from the coverage area A2, thereby effectively reducing the amount of misalignment.

[0062] Alternatively, as shown in FIG3 , the same effect can be achieved by setting the tabs 11 , 14 , and 15 located in the side regions to have a smaller width dimension than the tabs 12 and 13 in the middle region. That is, with the same positional deviation, the portion of the tabs 11 , 14 , and 15 protruding from the cover area A1 will be significantly less than the portion of the tabs 21 , 24 , and 25 protruding from the cover area A2 , thereby effectively reducing the amount of misalignment.

[0063] To fully illustrate the inventive concept and implementation of this application, the following detailed description is provided in conjunction with multiple embodiments. Figure 4 shows a schematic diagram of the structure of a battery electrode provided in one embodiment of this application. This battery electrode can be used as an anode electrode or a cathode electrode in the aforementioned wound battery cell.

[0064] As shown in FIG. 4 , the battery electrode 30 can be roughly divided into two main parts: the electrode body 31 and the electrode tab 32 .

[0065] The electrode body 31 is the main part of the battery electrode 10. In this application, for ease of description, the term "length direction L" is used to indicate the winding direction of the battery electrode 10 when forming the wound battery cell, and the term "width direction W" is used to indicate another direction perpendicular to the length direction.

[0066] The tab 32 is a protruding portion protruding from the edge of the pole piece body 31. It can protrude outward from one side of the pole piece body 31 in the width direction and serve as the current output end and connection end of the pole piece.

[0067] There can be multiple pole pieces 32, which are spaced apart in the area between the winding start end and the winding end end. In this application, "winding start end Ori" and "winding end Des" are used to describe the two ends of the battery pole pieces that make up the wound battery cell.

[0068] "Interval distribution" refers to a situation where there is a gap between two adjacent tabs 32. The gap can be reasonably controlled or adjusted so that different tabs 32 can be approximately located at an ideal position after winding.

[0069] In this application, a positive integer N greater than or equal to 3 is used to represent the number of pole pieces 32 (i.e., N ≥ 3). The specific value of N can be set according to actual needs and is not specifically limited here. For example, FIG4 shows N = 9 as an example.

[0070] Accordingly, the N tabs are sequentially referred to as the 1st tab to the Nth tab along the direction from the winding start to the winding end. In other words, the tab closest to the winding start is the 1st tab, and the tab closest to the winding end is the Nth tab.

[0071] The widths of the nth to n+kth tabs are greater than the widths of the remaining tabs. n and k are both positive integers greater than 1, and their specific values ​​can be determined based on actual needs (i.e., the first tab is excluded from the nth tab and does not belong to the nth tab).

[0072] In addition, it is also necessary to ensure that n+k is a value less than N (ie, the n+kth tab is excluded from the Nth tab and does not belong to the Nth tab).

[0073] At least one advantageous aspect of the battery electrode provided in the embodiment of the present application is that by setting the electrode tabs located in the middle area of ​​the electrode tabs to a larger width dimension, a relatively large coverage area can be provided, so that the electrode tabs located at the edges of the electrode tabs on both sides can be covered as much as possible by the coverage area even when there is a large position deviation, thereby reducing and lowering the amount of misalignment, thereby achieving the effect of improving battery safety.

[0074] In some embodiments, when N is a multiple of 3, the values ​​of n and k can both be N / 3, thereby evenly dividing the N tabs into a first tab group close to the starting end of the winding, a second tab group close to the ending end of the winding, and a third tab group located between the first tab group and the second tab group.

[0075] Alternatively, when N is not a multiple of 3, the values ​​of n and k can be determined by rounding up or down, which can also achieve the effect of roughly dividing the N tabs into three tab groups. For example, when the number of tabs is 20, the tabs can be divided into three groups of 7, 6, and 7, or into three groups of 6, 8, and 6.

[0076] The average width of the first tab group is set to be smaller than that of the third tab group, and the average width of the second tab group is also set to be smaller than that of the third tab group. In other words, the third tab group has a larger average width than the first and second tab groups.

[0077] In this application, the term "average width" is used to refer to the average width of all tabs in the same tab group. Of course, the difference between the width of each tab and the average width can be controlled within a reasonable range.

[0078] Setting the average width difference between the first and third tab groups to between 5 mm and 15 mm can better reduce the impact of tab misalignment. Furthermore, setting the average width difference between the first and third tab groups to between 8 mm and 10 mm can achieve the best effect.

[0079] In other optional embodiments, the difference between the average widths of the third tab group and the second tab group can also be controlled to be between 5 mm and 15 mm to further reduce the impact of tab misalignment. Furthermore, the best effect can be achieved when the difference is between 8 mm and 10 mm.

[0080] Specifically, in accordance with the difference in the above average width, the width of each tab in the first tab group can be controlled to be between 25 mm and 40 mm. The width of each tab in the second tab group can be between 25 mm and 40 mm. The width of each tab in the third tab group can be between 35 mm and 50 mm.

[0081] FIG5 is a schematic diagram showing a manufacturing process of a battery electrode sheet according to one embodiment of the present application. As shown in FIG5 , the manufacturing process of the battery electrode sheet may include the following steps:

[0082] S10. Prepare a current collector. The current collector is a conductive substrate. For example, it may include, but is not limited to, one or more conductive metal thin layers such as aluminum mesh, aluminum foil, and copper foil. The current collector preparation may specifically include cutting or trimming into a suitable sheet structure according to the desired size and shape, performing cleaning and surface treatment processes, and ensuring a clean and smooth metal surface, among other steps.

[0083] S20. The active material solution is evenly coated on the current collector. The active material is a key component for storing and releasing charge. Its specific composition and proportion can be determined based on the battery design requirements. The active material can be evenly dispersed in the solution through stirring and dispersion processes to obtain the desired active material solution.

[0084] Specifically, by applying different types of active material solutions, corresponding types of battery pole pieces can be produced. For example, when applying an anode active material, an anode pole piece can be produced. Exemplarily, the anode active material includes, but is not limited to, one or more of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium nickel oxide, lithium manganese iron phosphate, lithium vanadium phosphate, lithium iron phosphate, and lithium-rich manganese-based materials.

[0085] For example, when a cathode active material is applied, a cathode electrode sheet can be produced. For example, the cathode active material includes, but is not limited to, one or more of artificial graphite, natural graphite, soft carbon, hard carbon, graphene, mesocarbon microbeads, silicon-based materials, tin-based materials, lithium carbonate, or other metals capable of forming an alloy with lithium.

[0086] S30: Curing the active material coating on the current collector. For example, curing can be performed in an oven, using hot air, or using ultraviolet light, etc., as long as the solvent can be removed and the active material layer can be stably bonded to the current collector. This is not specifically limited here.

[0087] S40, shearing the current collector with the cured active material coating into a desired shape and size. For example, the shearing can be performed by cutting tools, molds, or laser cutting, etc., which are not specifically limited here.

[0088] In some embodiments, through appropriate process design, during the manufacturing process of the battery electrode sheet, only a portion of the current collector is covered with the active material coating, while a portion of the edge is left uncovered. Subsequently, the N tabs described above are formed by cutting the portion not covered with the active material coating. Alternatively, the N tabs described above can be formed by electrically connecting multiple independent tab components to the current collector through bonding or welding.

[0089] Figure 6 is a partial structural diagram of a battery electrode according to one embodiment of the present application. As shown in Figure 6, in addition to the electrode body 31 and the tab 32, there may also be a transitional connection portion between the two.

[0090] In this application, the transition portion between the tab body 31 and the tab 32 may be referred to as an “extension portion 33 .” The extension portion 33 has a first end 33 a connected to the tab body 31 and a second end 33 b connected to the tab 32 .

[0091] It should be noted that the terms "first end" and "second end" are used only to distinguish the two terminal ends of the extension portion 33 and are not intended to limit its specific structure or implementation. For example, when a tab is formed by cutting the edge of a current collector, the extension portion 33 may be located within the current collector, in the transition region between the tab body 31 coated with the active material coating and the tab 32 not coated with the active material coating.

[0092] 6 , the width of the first end 33a of the extension portion 33 is greater than the width of the second end 33b thereof. In other words, the extension portion 33 is narrower at the top and wider at the bottom in the direction toward the tab 32 .

[0093] The narrow upper and wide lower extension 33 can, on the one hand, prevent the connection between the tab and the pole piece from being too sharp, thereby reducing the risk of the separator being punctured. On the other hand, it can also increase the width of the connection between the tab and the pole piece, thereby preventing the connection from breaking or unnecessary deformation during the winding process, and better improving the problem of tab misalignment.

[0094] Specifically, the difference in width between the first end 33a and the second end 33b can be reasonably controlled. A larger difference can enable the extension portion 33 to achieve a better effect (i.e., more effectively reduce sharpness and avoid cracking). However, the requirements for manufacturing equipment and cutting processes required to realize and prepare the extension portion 33 with a larger width difference will be significantly increased.

[0095] Surprisingly, it was found that the best effect can be achieved by properly controlling the difference between the width of the first end and the second end within 2-6 mm, thus achieving a balance between the effect and the process.

[0096] If the width difference between the first and second ends is less than 2 mm, the positive effect of the extension 33 will be difficult to achieve, and the effect achieved will be insignificant. However, if the width difference between the first and second ends is greater than 6 mm, the requirements for manufacturing equipment and cutting technology will be significantly increased.

[0097] In an optional embodiment, please continue to refer to FIG. 6 , the transition connection portion between the pole tab and the pole piece body may be configured as an arc chamfer R.

[0098] Rounding Radius (R angle) refers to the process of rounding the edges of sharp corners to improve their smoothness.

[0099] Specifically, as shown in FIG7 , the arc chamfer can be defined and distinguished by the angle α formed between two straight lines tangent to the arc.

[0100] At least one advantage of providing a circular chamfer at the connection portion is that it can improve the stress distribution at the sharp corner between the tab and the pole piece body, reduce stress concentration and provide sufficient support, thereby enhancing the connection strength and durability.

[0101] Specifically, the angle α of the arc chamfer can be reasonably controlled. A larger angle α can enhance the support for the tab, but will result in an unnecessary reduction in the height of the tab protruding from the pole piece body, causing unnecessary impact on the energy density of the secondary battery.

[0102] When the angle α of the arc chamfer is properly controlled within a range of 95° to 150°, a balance between tab height and support can be achieved, ensuring sufficient support without significantly affecting battery energy density.

[0103] Furthermore, when the angle range is set to 120 to 130° (ie, when α is between 120 and 130°), the best balancing effect can be achieved.

[0104] In some embodiments, please continue to refer to FIG6 , the extension portion 33 is coated with an active material coating, which can play a certain supporting role.

[0105] Specifically, the active material surface density of the active material coating can be appropriately controlled. A higher active material surface density provides stronger support, preventing the tab from unexpectedly deforming during the winding process. However, this also increases the risk of the active material falling off and puncturing the separator during cutting, negatively impacting battery safety.

[0106] Properly setting the active material surface density to 60-100 g / m2 can achieve a balance between support and the risk of active material falling. While providing strong support, it does not significantly increase the risk of active material falling and the risk of the isolation membrane being punctured.

[0107] Based on the same technical concept, this application also provides an electrical device comprising any of the aforementioned secondary batteries. The electronic devices of this application include, but are not limited to, mobile phones, laptops, tablet computers, game consoles, drones, electric cars, electric bicycles, power tools, and Bluetooth headsets.

[0108] Hereinafter, examples and comparative examples are given to further illustrate the embodiments of the present application.

[0109] 1) Preparation process of lithium-ion batteries:

[0110] 1.1) Preparation of positive electrode sheet:

[0111] Lithium cobalt oxide (CCO), a conductive agent (acetylene black), and a binder (PVDF) were mixed in a mass ratio of 94:3:3. N-methylpyrrolidone was then added as a solvent to create a slurry with a solids content of 75%, which was then stirred evenly. The slurry was evenly coated on one surface of a 12μm-thick aluminum foil, dried at 90°C, and cold-pressed to produce a positive electrode sheet with a 100μm-thick CCO layer. The above steps were repeated on the other surface of the sheet to obtain a double-sided CCO sheet. The CCO sheet was cut and welded to aluminum tabs for later use.

[0112] 1.2) Preparation of negative electrode sheet

[0113] Artificial graphite, the negative electrode active material, and styrene-butadiene rubber, the binder, are mixed in a mass ratio of 98:2. Deionized water is then added as a solvent to create a slurry with a solids content of 70%, which is then stirred evenly. The slurry is evenly coated on one surface of an 8μm-thick copper foil, dried at 110°C, and cold-pressed to produce a negative electrode sheet with a 150μm-thick negative electrode active material layer. The coating process is then repeated on the other surface of the negative electrode sheet to produce a negative electrode sheet coated on both sides with the negative electrode active material layer. The negative electrode sheet is cut and welded with nickel tabs before use.

[0114] 1.3) Preparation of isolation membrane

[0115] Alumina and polyacrylate were mixed in a 90:10 mass ratio and dissolved in deionized water to form a ceramic slurry with a solid content of 50%. The slurry was then evenly coated onto one side of a porous substrate (polyethylene, 7 μm thick, 0.073 μm average pore size, 26% porosity) using a micro-dimpled coating method. After drying, a double-layer structure of ceramic coating and porous substrate was formed, with a thickness of 2.5 μm.

[0116] Polyvinylidene fluoride and polyacrylate were mixed in a mass ratio of 96:4 and dissolved in deionized water to form a polymer slurry with a solid content of 50%. The polymer slurry was then evenly applied to both surfaces of the ceramic coating and porous substrate double-layer structure using a micro-dimpled coating method. After drying, the separator was formed. The thickness of the single-layer coating formed by the polymer slurry was 2 μm.

[0117] 1.4) Preparation of electrolyte

[0118] In an environment with a water content of less than 10 ppm, non-aqueous organic solvents of ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), propyl propionate (PP), and vinylene carbonate (VC) are mixed in a mass ratio of 20:30:20:28:2, and then lithium hexafluorophosphate (LiPF6) is added to the non-aqueous organic solvent to dissolve and mix evenly to obtain an electrolyte, wherein the mass ratio of LiPF6 to the non-aqueous organic solvent is 8:92.

[0119] 1.5) Preparation of lithium-ion batteries:

[0120] First, the prepared positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator positioned between the positive and negative sheets to provide separation. The electrode assembly is then wound to form a spherical aluminum-plastic film. After dehydration at 80°C, the electrolyte is injected and the battery is packaged. The lithium-ion battery is then produced through a series of processes, including formation, degassing, and shaping.

[0121] 2) Preparation of lithium-ion battery samples:

[0122] By using the lithium-ion battery preparation process described in step 1) above, and in accordance with the tab process parameters shown in Tables 1-1 to 1-5 below, a plurality of corresponding lithium-ion battery samples were produced.

[0123] Among them, multiple identical lithium-ion battery samples are made for each sample number, and are used for different performance tests.

[0124] In the following Tables 1-1 to 1-5, the anode tabs are taken as an example, wherein each lithium-ion battery sample is provided with 9 anode tabs.

[0125] In the above Tables 1-1 to 1-5:

[0126] W1 is the average width of the first, second, third, seventh, eighth and ninth tabs, in millimeters (mm).

[0127] W2 is the average width of the 4th, 5th and 6th anode tabs, in millimeters (mm).

[0128] D1 is the difference obtained by subtracting W1 from W2, and the unit is millimeter (mm).

[0129] D2 is the width difference between the first end and the second end of the extension portion between each anode tab and the anode plate body, in millimeters (mm).

[0130] The angle of the R angle is: the angle α of the arc chamfer of the extension between each tab and the pole piece body in the lithium-ion battery sample, in degrees (°).

[0131] The active material surface density is: in the lithium-ion battery sample, the active material surface density of the active material coating covering the extension between each tab and the pole body, in grams per square meter (g / m2).

[0132] 3): Rate discharge test method

[0133] 3.1) At 25°C, charge the battery at a rate of 0.2C to 4.4V, then charge at a constant voltage until the battery is fully charged. After standing for 30 minutes, discharge the battery at a rate of 0.2C to 3.0V. Record the discharged capacity as the actual battery capacity of the lithium-ion battery sample.

[0134] 3.2) Fully charge the battery again as in step 3.1) above, let it rest for 30 minutes, and then discharge it at a rate of 3C to 3.0V. Record the discharged capacity as the current battery capacity of the lithium-ion battery sample.

[0135] 3.3) Calculate the ratio of the actual battery capacity to the current battery capacity to obtain the first capacity retention rate of the lithium-ion battery sample.

[0136] 4): Cyclic performance test method

[0137] 4.1) At 45°C, charge the battery to 4.4V at 1C DC, then charge to 0.02C at a constant voltage. After 30 minutes of rest, discharge the battery to 3.0V at 1C DC. Record the initial discharge capacity of the lithium-ion battery sample.

[0138] 4.2) After re-performing the above step 4.1) 1000 times, the discharge capacity of the lithium-ion battery sample after cycling was recorded;

[0139] 4.3) Calculate the ratio of the initial battery capacity to the discharge capacity after cycling to obtain the second capacity retention rate of the lithium-ion battery sample.

[0140] 5) Drop test method:

[0141] 5.1) A lithium-ion battery sample charged to 100% SOC at a constant voltage was dropped freely from a height of 1.5 meters onto a smooth steel plate surface. The order of the drops was: front-back-bottom-top-left-right of the lithium-ion battery sample.

[0142] 5.2) After each round of testing, measure the secondary battery voltage and inspect the secondary battery appearance. One round of testing consists of one continuous drop test on each surface.

[0143] 5.3) After 10 rounds of drop testing, if the lithium-ion battery sample does not get hot, catch fire, explode, leak, or emit smoke, and the voltage drop is less than 30mV, it is considered to have passed the drop test; otherwise, it is considered to have failed the drop test.

[0144] 6) Impact resistance test method:

[0145] 6.1) After charging the lithium-ion battery sample to 100% SOC at a constant voltage, discharge it at a constant current at the rated operating current for 30 minutes.

[0146] 6.2) Control the lithium-ion battery sample to impact the smooth steel plate surface with an acceleration of 10G along the winding axis of the lithium-ion battery sample.

[0147] 6.3) After five consecutive impacts, if the lithium-ion battery sample does not get hot, catch fire, explode, leak, or emit smoke, and the voltage drop is less than 30mV, it is considered to have passed the impact test; otherwise, it is considered to have failed the impact test.

[0148] 7) Energy density test method:

[0149] 7.1) At 25°C, charge the battery at a rate of 0.2C to 4.4V. Then, charge at a constant voltage until the battery is fully charged. After standing for 30 minutes, discharge the battery at a rate of 0.2C until the battery voltage drops to 3.0V. Record the discharged capacity as the actual battery capacity of the lithium-ion battery sample.

[0150] 7.2) The ratio of the discharge energy of a lithium-ion battery to the battery volume is taken as the volume energy density of the lithium-ion battery.

[0151] 7.3) Using the volumetric energy density of the lithium-ion battery sample numbered 3-1 as a reference value, calculate the ratio of the volumetric energy density of the remaining lithium-ion battery samples relative to that of sample numbered 3-1.

[0152] 8) Short circuit safety test:

[0153] A lithium-ion battery sample charged to 100% SOC at constant voltage was connected to a circuit with a loop resistance of less than 30 mΩ for a short-circuit test. The short-circuit test time was 10 seconds.

[0154] If the lithium-ion battery sample does not get hot, catch fire, explode, leak, or emit smoke, it is considered to have passed the test; otherwise, it is considered to have failed.

[0155] 9) Test results

[0156] 9.1) The lithium-ion battery samples in Table 1-1 were subjected to the above-mentioned "discharge rate test", "cycle performance test", "drop test" and "impact test" respectively, and the corresponding performance test results were obtained as shown in the following Table 2-1.

[0157] The following describes in detail the effect of the width dimension difference D1 on battery performance in combination with the performance test results shown in Table 2-1.

[0158] First, by comparing the drop test results of lithium-ion battery samples numbered 1-1 to 1-3 as a comparative example with those of the remaining lithium-ion battery samples numbered 1-4 to 1-16, it can be seen that when no width difference is set between the tabs, the lithium-ion battery samples have poor safety and fail the drop test. However, the remaining lithium-ion battery samples with a width difference all passed the drop test. This may be due to the lack of a width difference in the lithium-ion battery samples numbered 1-1 to 1-3, resulting in a large misalignment between the tabs.

[0159] Therefore, it is suggested that setting the width dimension difference D1 (ie, setting D1 not equal to zero) can improve the safety of lithium-ion battery samples.

[0160] Secondly, a comparison of the impact resistance test results for lithium-ion battery samples numbered 1-2 to 1-14 shows that when the width dimension difference D1 increases from 2mm to 5mm, the lithium-ion battery samples begin to pass the more stringent impact resistance test compared to the drop test, demonstrating improved safety. This is likely because a larger width difference provides greater misalignment margin, thereby improving the safety of the lithium-ion battery samples.

[0161] Therefore, it is suggested that setting a larger width dimension difference D1 can more effectively improve the safety of lithium-ion battery samples and make them have better tolerance and resistance to impact.

[0162] Again, the changing trends of the first and second capacity retention rates of the lithium-ion battery samples numbered 1-4 to 1-14 show that when the width dimension difference D1 varies from 5mm to 15mm, the first and second capacity retention rates remain essentially within a relatively high platform range, but the overall range of change is relatively small. However, after the width dimension difference D1 exceeds 15mm, the first and second capacity retention rates begin to decline significantly as the width dimension difference D1 increases.

[0163] Therefore, it is suggested that when the flat width dimension difference D1 is controlled within the range of 5 mm to 15 mm, the lithium-ion battery can have better charge and discharge performance while also having sufficient safety.

[0164] Finally, from the changing trends of the first capacity retention rate and the second capacity retention rate of the lithium-ion battery samples with sample numbers 1-4 to 1-12, it can be seen that when the width dimension difference D1 gradually increases from 5 mm to 8 mm, the first capacity retention rate and the second capacity retention rate gradually increase with the increase of the width dimension difference D1.

[0165] When the width dimension difference D1 varies from 8 mm to 10 mm, the first capacity retention ratio and the second capacity retention ratio are substantially maintained at a higher platform peak value.

[0166] However, as the width dimension difference D1 gradually increases from 10 mm to 15 mm, the first capacity retention rate and the second capacity retention rate begin to show a downward trend as the width dimension difference D1 increases, and begin to leave the platform peak.

[0167] Therefore, it is suggested that when the flat width dimension difference D1 is controlled within the range of 8 mm to 10 mm, the charge and discharge performance of the corresponding lithium-ion battery sample is at the platform peak and has the best performance.

[0168] In this application, the term "plateau peak" is used to describe a specific region in the variation curves of the first capacity retention rate and the second capacity retention rate, in which the value of the first capacity retention rate or the second capacity retention rate reaches or approaches a maximum value.

[0169] 9.2) After the lithium-ion battery samples in Table 1-2 were subjected to the above-mentioned "discharge rate test", "cycle performance test" and "impact resistance test", the corresponding performance test results were obtained as shown in the following Table 2-2.

[0170] The following describes in detail the effects of width dimensions W1 and W2 on battery performance in combination with the performance test results shown in Table 2-2.

[0171] The changing trends of the first capacity retention rate and the second capacity retention rate of the lithium-ion battery samples No. 2-1 to 2-10 show that:

[0172] When the width dimension W1 gradually increases from 20mm to 25mm, the first and second capacity retention rates significantly increase with the increase of the width dimension W1. Similarly, when the width dimension W2 gradually increases from 30mm to 35mm, the first and second capacity retention rates significantly increase with the increase of the width dimension W2.

[0173] When the width W1 varies from 25mm to 40mm, the first and second capacity retention rates basically maintain a relatively high platform peak. However, after the width W1 exceeds 40mm, the first and second capacity retention rates begin to decline significantly as the width W1 increases.

[0174] When the width W2 varies from 35mm to 50mm, the first and second capacity retention rates basically maintain a relatively high platform peak. However, after the width W2 exceeds 50mm, the first and second capacity retention rates begin to decline significantly as the width W2 increases.

[0175] Therefore, it is suggested that the width dimension W1 be controlled within the range of 25 mm to 40 mm, and when the width dimension W2 is within the range of 35 mm to 50 mm, the charge and discharge performance of the corresponding lithium-ion battery sample is at the platform peak, and has the best performance.

[0176] 9.3) After the lithium-ion battery samples in Tables 1-3 were subjected to the above-mentioned "Discharge Rate Test", "Cycling Performance Test", "Impact Resistance Test" and "Energy Density Test", the corresponding performance test results were obtained as shown in Tables 2-3 below.

[0177] The following describes in detail the effect of R angle changes on battery performance, combined with the performance test results shown in Table 2-3.

[0178] First, a comparison of the impact resistance test results for lithium-ion battery samples 3-1 and 3-2 to 3-15 shows that setting the R angle can improve the safety and impact resistance of lithium-ion battery samples. This is likely because increasing the R angle can help improve the support provided by the connection between the tab and the pole piece.

[0179] Therefore, it is suggested that the safety of lithium-ion battery samples can be improved by setting the R angle.

[0180] Secondly, the changing trends of the first capacity retention rate and the second capacity retention rate of the lithium-ion battery samples of sample numbers 3-1 to 3-15 show that: as the R angle gradually increases from 93° to 95°, the first capacity retention rate and the second capacity retention rate are significantly improved with the increase of the R angle. When the R angle is further increased from 95° to 150°, the first capacity retention rate and the second capacity retention rate also basically increase with the increase of the angle, but the overall change is small. However, after the R angle exceeds 150°, the first capacity retention rate and the second capacity retention rate basically do not change much, and the effect of improving the charge and discharge performance of the lithium-ion battery is not obvious.

[0181] This may be because the increase in R angle can make the transition between the tab and the pole piece body more natural and smooth, thereby reducing the local concentration and poor conduction of current at the connection between the tab and the pole piece.

[0182] This suggests that increasing the R angle has a positive impact on the charge and discharge performance of lithium-ion batteries. Furthermore, the R angle's primary impact on the charge and discharge performance of lithium-ion batteries occurs before 150°. Lithium-ion battery charge and discharge performance essentially reaches its peak at this angle.

[0183] Again, the energy density test results for lithium-ion battery samples numbered 3-1 to 3-15 show that as the R angle gradually increases from 95° to 150°, the energy density of the lithium-ion battery samples begins to gradually decrease, but the overall decrease is not large. However, after the R angle exceeds 150°, the energy density of the lithium-ion battery samples begins to drop significantly. This may be because the increase in the R angle affects the height of the tab, thereby correspondingly reducing the energy density of the lithium-ion battery.

[0184] This suggests that increasing the R angle excessively has a negative impact on the energy density of lithium-ion batteries. Furthermore, when the R angle exceeds 150°, the energy density of lithium-ion batteries decreases significantly.

[0185] From the above analysis, we can see that the optimal range of values ​​is between 95° and 150°. Within this range, the R angle can effectively improve the charge and discharge performance of lithium-ion batteries while avoiding a significant reduction in the energy density of lithium-ion battery samples, achieving a balance between the two.

[0186] Finally, the changing trends of the first and second capacity retention rates of lithium-ion battery samples numbered 3-3 to 3-15 show that when the R angle gradually increases from 95° to 120°, the first and second capacity retention rates increase relatively significantly with the increase in angle. When the R angle changes from 120° to 130°, the first and second capacity retention rates basically maintain a relatively high platform peak value, with a relatively small overall change.

[0187] The energy density test results for lithium-ion battery samples 3-3 to 3-15 show that when the R angle is 130°, the energy density of the lithium-ion battery samples remains essentially unchanged. However, as the R angle increases from 130° to 150°, the energy density of the lithium-ion battery samples begins to decline.

[0188] Therefore, it is suggested that when the R angle is controlled within the range of 120° to 130°, the optimal charge and discharge performance of the lithium-ion battery can be obtained while the energy density of the lithium-ion battery sample is substantially not reduced.

[0189] 9.4) The lithium-ion battery samples in Tables 1-4 were subjected to the aforementioned "discharge rate test", "cycle performance test", "impact resistance test" and "short circuit safety test", and the corresponding performance test results were obtained as shown in Tables 2-4 below.

[0190] The following describes in detail the effect of the width difference D2 on battery performance in conjunction with the performance test results shown in Tables 2-4.

[0191] First, a comparison of the impact resistance test results of lithium-ion battery samples numbered 4-1 and 4-2 shows that when a width difference is present (i.e., width difference D2 is not equal to 0), the lithium-ion battery sample is safer and can withstand stronger impacts. This may be because the width difference provides additional support, reducing the risk of fracture at the connection between the tab and the pole piece.

[0192] This suggests that the safety of the lithium-ion battery can be improved by setting the first end of the extension portion to be larger in width than the second end.

[0193] Secondly, from the changing trends of the first capacity retention rate and the second capacity retention rate of the lithium-ion battery samples with sample numbers 4-2 to 4-12, it can be seen that as the width difference D2 gradually increases from 1.0 mm to 2.0 mm, the increase in the width difference D2 between the first capacity retention rate and the second capacity retention rate is significantly improved.

[0194] When the width difference D2 increases from 2.0mm to 6.0mm, the first and second capacity retention rates also increase substantially with the increase in the width difference D2, but the overall magnitude of change is relatively small. After the width difference D2 exceeds 6.0mm, while the first and second capacity retention rates continue to improve, the improvement is less pronounced. This may be because a larger width difference D2 provides sufficient support, reducing the deformation at the connection between the tab and the pole piece, and improving the ability to pass current. However, the optimal effect is achieved after exceeding 6mm.

[0195] Therefore, increasing the width difference D2 has a positive effect on improving the charge and discharge performance of lithium-ion batteries. Furthermore, the width difference D2's primary impact on the charge and discharge performance of lithium-ion batteries occurs before 6.0 mm. The charge and discharge performance of lithium-ion batteries typically reaches its peak within this data range.

[0196] Considering that a larger width difference D2 places higher demands on cutting technology and equipment, resulting in a significant increase in processing difficulty, controlling the width difference D2 below 6.0 mm is the optimal value range, which can not only effectively improve the charge and discharge performance of lithium-ion batteries, but also avoid the problem of greater processing difficulty.

[0197] Secondly, the short-circuit safety test results for lithium-ion battery samples 4-1 to 4-12 show that when the width difference D2 exceeds 2mm, the lithium-ion battery samples all pass the test, but once the width difference D2 is less than this value, the lithium-ion battery fails the test. This may be because a larger width difference D2 can reduce the sharpness of the connection between the tab and the pole piece, making it relatively smoother and reducing the risk of puncturing the separator.

[0198] Therefore, it is suggested that the width difference D2 also has a positive effect on improving the short-circuit safety of lithium-ion batteries.

[0199] Through analysis, it can be seen that controlling the width difference D2 within the range of 2.0mm to 6.0mm is the optimal numerical range. This can effectively improve the short-circuit safety of lithium-ion batteries, avoid the problem of difficult processing, and achieve better charge and discharge performance.

[0200] 9.5) The lithium-ion battery samples in Tables 1-5 were subjected to the aforementioned "discharge rate test," "cycle performance test," "impact resistance test," and "short-circuit safety test," respectively, and the corresponding performance test results were obtained as shown in Tables 2-5 below.

[0201] The following describes in detail the effect of active material surface density on battery performance in conjunction with the performance test results shown in Tables 2-5.

[0202] First, the changing trends of the first capacity retention rate and the second capacity retention rate of the lithium-ion battery samples of sample numbers 5-1 to 5-11 show that: when the active material surface density gradually increases from 45g / m2 to 60g / m2, the first capacity retention rate and the second capacity retention rate increase significantly with the increase in the active material surface density. When the active material surface density changes from 60g / m2 to 100g / m2, the first capacity retention rate and the second capacity retention rate also basically increase accordingly, but the overall change is not large and begins to approach the platform peak. After the active material surface density exceeds 100g / m2, the overall change in the first capacity retention rate and the second capacity retention rate is small and does not increase accordingly with the increase in the active material surface density. This may be because a larger active material surface density can provide stronger support for the tabs, reducing the deformation of the tabs during the winding process and the positional offset caused by uneven tension, thereby reducing the misalignment of the tabs. On the other hand, a larger active material surface density can provide more active material, which helps to improve the output power and storage capacity of the lithium-ion battery.

[0203] This suggests that increasing the active material areal density has a positive effect on improving the charge and discharge performance of lithium-ion batteries. Furthermore, the effective range for improving the charge and discharge performance of lithium-ion batteries lies before the active material areal density reaches 100 g / m². The charge and discharge performance of lithium-ion batteries generally reaches a plateau peak in this data range.

[0204] Secondly, the short-circuit safety test results for lithium-ion battery samples 5-9 to 5-11 show that when the active material areal density exceeds 100g / m², the lithium-ion battery samples fail the short-circuit safety test. This may be because excessively high active material areal density increases the risk of active material falling during the winding process, thereby reducing the isolation effect of the separator and resulting in reduced short-circuit safety.

[0205] This suggests that excessively high active material surface density will have a negative impact on the safety performance of lithium-ion battery samples.

[0206] Through the above analysis, we can see that when the active material surface density is controlled within the range of 60g / m2 to 100g / m2, it can fully improve the charge and discharge performance of the lithium-ion battery while ensuring that the short-circuit safety of the lithium-ion battery sample will not be significantly weakened. This is a relatively ideal numerical range.

[0207] The above description is merely an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A battery pole piece, characterized in that: include: The pole piece body has a length direction and a width direction perpendicular to the length direction; N pole tabs are spaced apart and distributed in a region between a winding start end and a winding end end of the pole piece body; the N pole tabs include a first pole tab to an Nth pole tab, and the first pole tab to the Nth pole tab are arranged along a direction from the winding start end to the winding end end; Each of the pole tabs is connected to one side of the pole piece body in the width direction and has a width dimension in the length direction of the pole piece body; Among the nth to n+kth tabs, the width dimension of each tab is greater than the width dimensions of the remaining tabs; N is a positive integer greater than 3, and n+k is less than N; n and k are both positive integers greater than 1.

2. The battery electrode according to claim 1, characterized in that: The N tabs are evenly divided into the following three tab groups: a first tab group close to the winding starting end; a second tab group close to the winding termination end; as well as The third tab group is located between the first tab group and the second tab group: The average tab width of the first tab group is smaller than the average tab width of the third tab group, and the average tab width of the second tab group is smaller than the average tab width of the third tab group.

3. The battery electrode according to claim 2, characterized in that: The difference between the average tab widths of the first tab group and the third tab group is between 5 mm and 15 mm; and / or the difference between the average tab widths of the third tab group and the second tab group is between 5 mm and 15 mm.

4. The battery electrode according to claim 3, characterized in that: The difference between the average tab widths of the first tab group and the third tab group is between 8 mm and 10 mm; and / or the difference between the average tab widths of the third tab group and the second tab group is between 8 mm and 10 mm.

5. The battery electrode according to any one of claims 2 to 5, characterized in that: The width of each of the tabs in the first tab group is between 25 mm and 40 mm; The width of each of the tabs in the second tab group is between 25 mm and 40 mm; The width of each of the tabs in the third tab group is between 35 mm and 50 mm.

6. The battery electrode according to any one of claims 1 to 5, characterized in that: The pole piece body further comprises an extension portion extending along the width direction; the extension portion comprises: a first end connected to the pole piece body and a second end connected to the pole tab; The width of the first end in the length direction of the pole piece body is greater than the width of the second end in the length direction of the pole piece body.

7. The battery electrode according to claim 6, characterized in that: The difference between the width dimensions of the first end and the second end is between 2-6 mm.

8. The battery electrode according to claim 6, characterized in that: The surface density of the active material coated on the extension is 60-100 g / m 2 .

9. The battery electrode according to any one of claims 1 to 5, characterized in that: The connection portion between the pole ear and the pole piece body is configured as an arc chamfer.

10. The battery electrode according to claim 8, characterized in that: The angle range of the arc chamfer is 95° to 150°.

11. The battery electrode according to claim 9, characterized in that: The angle range of the arc chamfer is 120° to 130°.

12. A secondary battery, characterized in that: include: An electrode assembly is formed by winding anode and cathode electrodes spaced apart; a separator is provided between the electrode assemblies; Wherein, the cathode electrode sheet and / or the anode electrode sheet is a battery electrode sheet as described in any one of claims 1-11.

13. An electrical device, characterized in that: include: The secondary battery according to claim 12.

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