Electrode assembly, battery and electric equipment

Abstract

The invention discloses an electrode assembly, a battery with the electrode assembly and electric equipment with the battery, the electrode assembly comprises a first pole piece, a second pole piece and an isolating membrane, the first pole piece is provided with a first tab and a third tab, the second pole piece is provided with a second tab, and the first pole piece, the isolating membrane and the second pole piece are wound to form the electrode assembly. The first pole piece comprises a first current collector and a first active material layer, and the first active material layer is arranged on the surface of the first current collector to form a first coating area; the first tab and the third tab are arranged in the first coating area at intervals, the first coating area is divided into a first part, a second part and a third part, and the length ratio of the first part to the second part to the third part is 1: (0.5-1.5): (0.5-1.5). And the projections of the first tab, the second tab and the third tab on the surface of the electrode assembly are not overlapped. According to the electrode assembly, the resistance difference between the adjacent tabs is reduced, the overcurrent capability of the electrode assembly is improved, and the temperature rise of the electrode assembly is reduced.

Description

[0001] This application is a divisional application of the invention patent application filed by the applicant on August 19, 2021, entitled "Electrode Assembly, Battery and Electrical Device" (application number CN202110955883.1). Technical Field

[0002] This invention relates to the field of electrochemical device technology, and more particularly to an electrode assembly and a battery and electrical device having the electrode assembly. Background Technology

[0003] With the application of 5G, consumers have increasingly higher requirements for the battery performance of portable electronic products such as smartphones and tablets. Existing batteries suffer from the problem of high battery and overall device temperature rise; excessively high temperatures reduce the performance of both the battery and the electronic product. Current batteries use a bipolar structure, which limits their overall overcurrent capacity, thus resulting in persistently high temperature rise for both the battery and the device. Summary of the Invention

[0004] In view of the above, it is necessary to propose an electrode assembly and a battery and electrical device having the electrode assembly.

[0005] This application provides an electrode assembly including a first electrode, a second electrode, and a separator. The first electrode has a first tab, the second electrode has a second tab, and the separator is disposed between the first and second electrodes. The first electrode, the separator, and the second electrode are wound together to form the electrode assembly. The electrode assembly also includes a third tab disposed on the first electrode. The first electrode includes a first current collector and a first active material layer. The first active material layer is disposed on the surface of the first current collector to form a first coating area. Along a first direction, the first active material layer extends in a strip shape. The first tab and the third tab are spaced apart in the first coating area. The first direction is the length direction of the first electrode in its unfolded state. Along the first direction, the first tab and the third tab divide the first coating area into a first part, a second part, and a third part. The length ratio of the first part, the second part, and the third part is 1:(0.5-1.5):(0.5-1.5), preferably 1:(0.8-1.2):(0.8-1.2). Along a third direction, the projections of the first tab, the second tab, and the third tab on the surface of the electrode assembly do not overlap; wherein, the third direction is the thickness direction of the electrode assembly. In embodiments of this application, the first direction is the length direction of the electrode sheet in its unfolded state, and also the winding direction of the electrode assembly.

[0006] Thus, the electrode assembly shunts the current by adding a third tab on the first electrode plate, and the first tab and the third tab divide the first coating area according to a predetermined ratio, thereby reducing the resistance difference between adjacent tabs and giving full play to the advantages of charging speed and temperature rise reduction, so as to achieve the purpose of improving the current carrying capacity of the electrode assembly and reducing the temperature rise of the electrode assembly.

[0007] In some embodiments, a first groove and a third groove are spaced apart on the first active material layer. The first electrode tab is disposed in the first groove, and the third electrode tab is disposed in the third groove. Along the first direction, the length of the first active material layer is L, and the distance between the first groove and the third groove is H, wherein |L / 2-H|≤100mm, and L≥700mm. This reduces the problem of short circuits due to excessively small distances between the electrodes and also facilitates the division of the first coating area by the first and third electrodes according to a preset ratio. The first groove and the third groove are formed by a deficiency in the first active material layer. According to one embodiment of this application, the aforementioned deficiency in the active material layer can expose the current collector or other coatings applied to the surface of the current collector.

[0008] In some embodiments, along the second direction, the first groove penetrates the first active material layer. The first groove can be formed on the first electrode sheet by gap coating, reducing the manufacturing difficulty of the electrode sheet. The second direction is perpendicular to the first direction. In the unfolded state of the electrode sheet, the second direction refers to the width direction of the electrode sheet, or the length direction of the electrode assembly in the wound state.

[0009] In some embodiments, along the second direction, the first edge of the first groove is flush with the first side of the first current collector, and the second edge of the first groove is spaced apart from the second side of the first current collector, which helps to reduce the loss of the active material layer and maintain the energy density of the cell assembly.

[0010] In some embodiments, along the first direction, the side of the first tab is spaced apart from the side of the first groove to reduce the problem of the tab contacting the active material.

[0011] In some embodiments, the distance between the side of the first tab and the side of the first groove along the first direction is 2-2.5 mm, so as to install the first tab within the tolerance limits of the device and reduce the problem of the tab contacting the active material.

[0012] In some embodiments, along the first direction, the width of the first tab is 6-8 mm and the width of the first groove is 10-13 mm, so as to reduce the impact of excessive loss of active material on the cell energy density.

[0013] In some embodiments, the first tab includes a first section and a second section. The first section is disposed in the first groove and connected to the first current collector. The second section is bent toward the side of the first current collector away from the first section, so that the bent tab applies pressure to the electrode, which helps to strengthen the connection between the tab and the electrode and reduce the problem of the tab separating from the electrode due to external force.

[0014] In some embodiments, along the second direction, the first current collector includes a first side and a second side disposed opposite to each other, the first tab extends out of the first side and the third tab extends out of the second side, such that after the electrode assembly is wound and formed, the first tab and the third tab are located at opposite ends of the electrode assembly, and the distance between the first tab and the third tab in the first direction can be shortened, which facilitates the miniaturization of the battery.

[0015] In some embodiments, the first tab and the third tab are formed by extending a portion of the side surface of the first current collector beyond the first current collector. Specifically, the first tab and the third tab can be formed by cutting the first current collector, so that the coverage area of ​​the first active material layer can be preserved to the maximum extent, which is beneficial to improving the energy density of the electrode assembly.

[0016] In some embodiments, the second electrode includes a second current collector and a second active material layer, the second active material layer being disposed on the surface of the second current collector to form a second coating area, and the second tab being disposed on the second coating area.

[0017] In some embodiments, the second tab divides the second coating area into a fourth part and a fifth part. Along the winding direction of the second electrode sheet, the length ratio of the fourth part to the fifth part is 1:(0.5-1.5), preferably 1:(0.8-1.2, which helps to reduce the internal resistance difference between adjacent tabs.

[0018] In some embodiments, the electrode assembly further includes a fourth tab disposed in the second coating area and spaced apart from the second tab. The second tab and the fourth tab divide the second coating area into a fourth portion, a fifth portion, and a sixth portion. Along the winding direction of the second electrode sheet, the length ratio of the fourth portion, the fifth portion, and the sixth portion is 1:(0.5-1.5):(0.5-1.5), preferably 1:(0.8-1.2):(0.8-1.2). This further shunts the current and reduces the temperature rise of the electrode assembly.

[0019] In some embodiments, along a third direction, the projections of the first tab, the second tab, and the third tab on the surface of the electrode assembly do not overlap; wherein, the third direction is perpendicular to the first direction. In embodiments of this application, the third direction is the thickness direction of the electrode assembly. The staggered arrangement of multiple tabs can reduce the problem of uneven electrode assembly thickness caused by the superposition of tab thicknesses, which is beneficial to improving the problem of electrode assembly deformation during multiple charge-discharge processes.

[0020] In some embodiments, along the third direction, there are at least two layers of the first electrode or the second electrode between adjacent tabs, preferably four layers, which helps to avoid multiple adhesive patches on a single electrode layer, resulting in inconsistent electrode interfaces and the problem of circular interfaces.

[0021] In some embodiments, the first electrode is a cathode and the second electrode is an anode. A first active material layer is provided on both opposite surfaces of the current collector at the winding start end of the first electrode, forming a double-sided region at the winding start end. No second active material layer is provided on either side of the current collector at the winding start end of the second electrode, forming an empty foil region at the winding start end. This helps to reduce lithium plating problems.

[0022] In some embodiments, the winding start ends of the first electrode and the second electrode are both double-sided regions, and the winding end ends are single-sided regions transitioning to empty foil regions. This structure is beneficial for balancing the active materials on the two electrodes and improving the energy density of the electrode assembly.

[0023] This application also provides a battery, which includes a housing and the electrode assembly described in the above embodiments, wherein the electrode assembly is disposed within the housing.

[0024] This application also provides an electrical device, which includes circuit elements and the battery described in the above embodiments, wherein the circuit elements are electrically connected to the battery. The electrical device includes, but is not limited to, electronic devices such as mobile phones, computers, and mobile terminals. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the winding structure of the electrode assembly in one embodiment.

[0026] Figure 2 yes Figure 1 The front and side views show the unfolded structure of the first electrode in the electrode assembly shown.

[0027] Figure 3 yes Figure 1 The front and side views show the unfolded structure of the second electrode in the electrode assembly shown.

[0028] Figure 4 yes Figure 1 The front view of the electrode assembly shown.

[0029] Figure 5 yes Figure 1 The diagram shows the structure of the two sides of the electrode assembly after the tabs are removed from the first and second electrodes.

[0030] Figure 6 This is a schematic diagram of the structure of the two sides of the first electrode after the tab is removed in one embodiment.

[0031] Figure 7 This is a schematic diagram of a partial connection structure between the tab and the electrode sheet in one embodiment.

[0032] Figure 8 This is a schematic diagram of the structure of the two sides of the first electrode in one embodiment.

[0033] Figure 9 This is a schematic diagram of the structure of the two sides of the second electrode in one embodiment.

[0034] Figure 10 It has Figure 8 and Figure 9 A schematic diagram of the winding structure of the electrode assembly of the electrode sheet shown.

[0035] Figure 11 yes Figure 10 The front view of the electrode assembly shown.

[0036] Figure 12 This is a schematic diagram of the structure of the two sides of the first electrode in one embodiment.

[0037] Figure 13 This is a schematic diagram of the structure of the two sides of the second electrode in one embodiment.

[0038] Figure 14 It has Figure 12 and Figure 13 A schematic diagram of the winding structure of the electrode assembly of the electrode sheet shown.

[0039] Figure 15 yes Figure 14 The front view of the electrode assembly shown.

[0040] Figure 16 This is a schematic diagram of the structure of the two sides of the first electrode in one embodiment.

[0041] Figure 17 This is a schematic diagram of the structure of the two sides of the second electrode in one embodiment.

[0042] Figure 18 It has Figure 16 and Figure 17A schematic diagram of the winding structure of the electrode assembly of the electrode sheet shown.

[0043] Figure 19 yes Figure 18 The front view of the electrode assembly shown.

[0044] Figure 20 This is a schematic diagram of the electrode assembly in a pair of proportions.

[0045] Figure 21 yes Figure 20 The front and side views of the first electrode in the electrode assembly shown.

[0046] Figure 22 yes Figure 20 The front and side views of the second electrode in the electrode assembly shown.

[0047] Figure 23 yes Figure 20 Histogram of the detection results of the internal resistance between adjacent tabs of the electrode assembly shown.

[0048] Figure 24 yes Figure 1 Histogram of the detection results of the internal resistance between adjacent tabs of the electrode assembly shown.

[0049] Figure 25 This is a simplified structural diagram of a battery in one embodiment.

[0050] Figure 26 This is a simplified structural diagram of an electrical device in one embodiment.

[0051] Explanation of main component symbols The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0053] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0054] The following disclosure provides many different embodiments or examples for implementing different structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0055] Please see Figure 1 , Figure 2 , Figure 3 and Figure 4 In a first embodiment of this application, the electrode assembly 100 includes a first electrode 10, a second electrode 20, and a separator 30. The first electrode 10 and the second electrode 20 have opposite polarities, and the separator 30 is disposed between the first electrode 10 and the second electrode 20. The first electrode 10, the separator 30, and the second electrode 20 are wound together to form the electrode assembly 100. The first electrode 10 has a first tab 40 and a third tab 60, and the first tab 40, the third tab 60, and the first electrode 10 have the same polarity. The second electrode 20 has a second tab 50, and the second tab 50 has the same polarity as the second electrode 20. The electrode assembly 100 of this application uses the third tab 60 in parallel to shunt the current flowing into the electrode assembly 100, thereby improving the current-carrying capacity of the electrode assembly 100.

[0056] Specifically, please refer to [the relevant document] again. Figure 2The first electrode 10 includes a first current collector 11 and a first active material layer 12. The first active material layer 12 is disposed on the surface of the first current collector 11 to form a first coating area. Along a first direction A, the first active material layer 12 extends in a strip shape, and the first tab 40 and the third tab 60 are spaced apart in the first coating area. Along the winding direction of the first electrode 10, i.e., the winding direction of the electrode assembly 100, the first tab 40 and the third tab 60 divide the first coating area into a first portion 111, a second portion 112, and a third portion 113. The length ratio of the first portion 111, the second portion 112, and the third portion 113 is 1:(0.5-1.5):(0.5-1.5), preferably 1:(0.8-1.2):(0.8-1.2). In the embodiments of this application, the first direction A is the length direction of the electrode in its unfolded state, and also the winding direction of the electrode assembly 100.

[0057] Furthermore, please refer again. Figure 3 The second electrode 20 includes a second current collector 21 and a second active material layer 22. The second active material layer 22 is disposed on the surface of the second current collector 21 to form a second coating area. The second tab 50 is disposed on the second coating area. The second tab 50 divides the second coating area into a fourth part 211 and a fifth part 212. Along the winding direction of the second electrode 20, i.e. the winding direction of the electrode assembly 100, the length ratio of the fourth part 211 to the fifth part 212 is 1:(0.5-1.5), preferably 1:(0.8-1.2.

[0058] Thus, the electrode assembly 100 achieves parallel current splitting by adding a third tab 60 on the first electrode 10. The first tab 40, the second tab 50, and the third tab 60 divide the length of the active material layer on the first electrode 10 and the second electrode 20 according to a predetermined ratio, which can reduce the resistance difference between adjacent tabs and make the internal resistance between adjacent tabs approximately the same. This fully utilizes the advantages of charging speed and temperature rise reduction, so as to achieve the purpose of improving the current carrying capacity of the electrode assembly and reducing the temperature rise of the electrode assembly.

[0059] Please see Figure 2 and Figure 5The first active material layer 12 has a first groove 121 and a third groove 122 spaced apart. The first tab 40 is disposed in the first groove 121, and the third tab 60 is disposed in the third groove 122. Along the first direction A, the length of the first active material layer 12 is L, and the distance between the first groove 121 and the third groove 122 is H, wherein |L / 2-H|≤100mm, and L≥700mm. This reduces the problem of short circuits caused by excessively small distances between the tabs, and also facilitates the division of the first coating area by the first tab 40 and the third tab 60 according to a preset ratio. The first groove 121 and the third groove 122 are formed by the absence of the first active material layer 12. According to one embodiment of this application, the absence of the first active material layer 12 can expose the first current collector 11, or expose other coatings coated on the surface of the first current collector 11.

[0060] The second active material layer 22 has a second groove 221, and the second tab 50 is disposed within the second groove 221. Along the first direction A, the second groove 221 is located approximately at the middle position of the second active material layer 22. The second groove 221 is formed by a gap in the second active material layer 22. According to one embodiment of this application, the gap in the second active material layer 22 may expose the second current collector 21, or expose other coatings applied to the surface of the second current collector 21.

[0061] To maintain the uniformity of the active material layer, the active material layer is missing on both sides of the current collector at the corresponding slot positions. That is, no active material layer is provided on both sides of the current collector in the first slot 121, the second slot 221, and the third slot 122, forming local empty foil areas.

[0062] Furthermore, along the second direction B, the first edge 1211 of the first groove 121 is flush with the first side 114 of the first current collector 11, and the second edge 1212 of the first groove 121 is spaced apart from the second side 115 of the first current collector 11. This helps to reduce the loss of the active material layer and maintain the energy density of the cell assembly. The second direction B is perpendicular to the first direction A. In the unfolded state of the electrode sheet, the second direction B refers to the width direction of the electrode sheet, or the length direction of the electrode assembly 100 in the wound state. The structures of the third groove 122 and the second groove 221 are roughly the same as the structure of the first groove 121, and will not be described again here.

[0063] During the manufacturing process of the first electrode 10 and the second electrode 20, after the active material layer is coated onto the surface of the current collector, a chemical reagent can be used to wash away part of the active material at the corresponding position of the active material layer, exposing the current collector to obtain the first groove 121, the second groove 221 and the third groove 122; alternatively, before the active material layer is coated onto the current collector, adhesive tape can be attached to the corresponding position, and after the active material layer is coated onto the surface of the current collector, the adhesive tape can be removed to expose the current collector, thereby obtaining the first groove 121, the second groove 221 and the third groove 122.

[0064] Please see Figure 6 In one embodiment of this application, along the second direction B, the first groove 121 penetrates the first active material layer 12. The first groove 121 can be formed on the first electrode 10 by intermittent coating, that is, the active material layer is intermittently coated on the surface of the current collector according to a preset program to form the first groove 121 and the third groove 122, etc., which helps to reduce the manufacturing process difficulty of the electrode.

[0065] Please refer to it again. Figure 2 and Figure 3 Along the first direction A, the side of the first tab 40 is spaced apart from the side of the first groove 121 to reduce the problem of the tab contacting the active material. Specifically, the distance between the side of the first tab 40 and the side of the first groove 121 is 2-2.5 mm to install the first tab 40 within the tolerance limits of the device and reduce the problem of the tab contacting the active material. In the embodiments of this application, along the first direction A, the width of the first tab 40 is 6-8 mm, and the width of the first groove 121 is 10-13 mm to reduce the impact of excessive loss of active material on the cell energy density. The dimensions of the second tab 50 and the third tab 60 are approximately the same as those of the first tab 40, and the dimensions of the second groove 221 and the third groove 122 are approximately the same as those of the first groove 121.

[0066] Please refer to it again. Figure 4 In the first embodiment, the first electrode 10 is a cathode plate, the second electrode 20 is an anode plate, and after the electrode assembly 100 is wound into shape, the first electrode tab 40, the second electrode tab 50 and the third electrode tab 60 are located at the same end of the electrode assembly 100, and the second electrode tab 50 is spaced between the first electrode tab 40 and the third electrode tab 60.

[0067] Furthermore, along the third direction C, the projections of the first tab 40, the second tab 50, and the third tab 60 on the surface of the electrode assembly 100 do not overlap. The third direction C is perpendicular to the first direction A. In the embodiments of this application, the third direction C is the thickness direction of the electrode assembly 100. The staggered arrangement of multiple tabs can reduce the problem of uneven electrode assembly thickness caused by the overlapping of tab thicknesses, which is beneficial for improving the problem of deformation of the electrode assembly during multiple charge-discharge cycles. Along the third direction C, adjacent tabs are spaced at least two layers of the first electrode sheet 10 or the second electrode sheet 20, preferably four layers apart, which helps to avoid multiple adhesive applications on a single electrode sheet, leading to inconsistent electrode interfaces and the problem of cyclic interfaces.

[0068] Please see Figure 2 and Figure 7 Furthermore, the first tab 40 includes a first section 41 and a second section 42. The first section 41 is disposed in the first groove 121 and connected to the first current collector 11. The second section 42 is bent toward the side of the first current collector 11 away from the first section 41, so that the bent tab applies pressure to the electrode, which helps to strengthen the connection between the tab and the electrode and reduce the problem of the tab separating from the electrode due to external force.

[0069] In some embodiments of this application, the first tab 40 and the third tab 60 may also be formed by a portion of the side surface of the first current collector 11 extending beyond the first current collector 11. The second tab 50 may be formed by a portion of the side surface of the second current collector 21 extending beyond the second current collector 21. Specifically, the first tab 40 and the third tab 60 can be formed by cutting the first current collector 11, and the second tab 50 can be formed by cutting the second current collector 21. In this way, the coverage area of ​​the first active material layer 12 and the second active material layer 22 can be preserved to the maximum extent, which is beneficial to improving the energy density of the electrode assembly 100.

[0070] Please see Figure 8 , Figure 9 , Figure 10 and Figure 11 The electrode assembly 200 of the second embodiment is substantially the same as the electrode assembly 100 of the first embodiment, except that in the second embodiment, the first electrode 10 is an anode, and the corresponding first electrode tab 40 and third electrode tab 60 are anode tabs; the second electrode 20 is a cathode, and the corresponding second electrode tab 50 is a cathode tab. After the electrode assembly 200 is wound and formed, the first electrode tab 40, the second electrode tab 50, and the third electrode tab 60 are located at the same end of the electrode assembly 200, and the second electrode tab 50 is spaced between the first electrode tab 40 and the third electrode tab 60.

[0071] Please see Figure 12 , Figure 13 , Figure 14 and Figure 15 The electrode assembly 300 of the third embodiment is substantially the same as the electrode assembly 100 of the first embodiment, except that, in the third embodiment, along the second direction B, the first tab 40 extends out of the first side 114 of the first current collector 11, and the third tab 60 extends out of the second side 115 of the first current collector 11. The second tab 50 is positioned on the second electrode sheet 20 in the same direction as the first tab 40. After the electrode assembly 300 is wound and formed, the second tab 50 and the first tab 40 are located at the same end of the electrode assembly 300, and the first tab 40 and the third tab 60 are located at opposite ends of the electrode assembly 300. The distance between the first tab 40 and the third tab 60 in the first direction A can be shortened, which facilitates the miniaturization of the battery.

[0072] Please see Figure 16 , Figure 17 , Figure 18 and Figure 19 The electrode assembly 400 of the fourth embodiment is substantially the same as the electrode assembly 100 of the first embodiment, except that in the fourth embodiment, the electrode assembly 400 further includes a fourth tab 70, which is disposed in the second coating area and spaced apart from the second tab 50. The second tab 50 and the fourth tab 70 divide the second coating area into a fourth part 211, a fifth part 212, and a sixth part 213. Along the winding direction of the second electrode sheet, the length ratio of the fourth part 211, the fifth part 212, and the sixth part 213 is 1:(0.5-1.5):(0.5-1.5), preferably 1:(0.8-1.2):(0.8-1.2). This further shunts the current and reduces the temperature rise of the electrode assembly 400.

[0073] After the electrode assembly 400 is wound and formed, the first electrode tab 40, the second electrode tab 50, the third electrode tab 60 and the fourth electrode tab 70 are located at the same end of the electrode assembly 400, and the second electrode tab 50 and the fourth electrode tab 70 are spaced apart between the first electrode tab 40 and the third electrode tab 60.

[0074] In some embodiments of this application, the first electrode 10 is a cathode and the second electrode 20 is an anode. A first active material layer 12 is provided on both opposite surfaces of the current collector at the winding start end of the first electrode 10, forming a double-sided region at the winding start end. No second active material layer 22 is provided on either side of the current collector at the winding start end of the second electrode 20, forming an empty foil region at the winding start end. This helps to reduce the occurrence of lithium plating problems inside the electrode assembly.

[0075] In some embodiments of this application, the winding start ends of the first electrode 10 and the second electrode 20 are both double-sided regions, and the winding end ends are single-sided regions transitioning to empty foil regions. This structure is beneficial for balancing the active materials on the two electrodes and improving the energy density of the electrode assembly.

[0076] Please see Figure 20 , Figure 21 and Figure 22 In the first comparative example, the electrode assembly 100' is substantially the same as the electrode assembly 100 of the first embodiment, except that in the first comparative example, the first tab 40 is disposed in the empty foil area at the starting end of the winding of the first electrode 10, and the third tab 60 is disposed in the first coating area of ​​the first electrode 10. The first tab 40 and the third tab 60 do not divide the first coating area according to a predetermined ratio. Figure 23 As can be seen, after the electrode assembly 100' is wound and formed, the internal resistance difference between adjacent tabs is significant. Please refer to... Figure 24 Compared with the first comparative example, in the first embodiment, after the electrode assembly 100 is wound and formed, the difference in internal resistance between adjacent tabs is significantly reduced.

[0077] The table below shows the test results of charging and temperature rise data of the electrode assembly 100 in the first embodiment and the electrode assembly 100' in the first comparative example under the same charging regime.

[0078] Table 1. Test results of charging speed As can be seen from the data in Table 1, the charging speed of the electrode assembly 100 in the first embodiment within 30 minutes is 3.2% higher than that of the first comparative embodiment. This proves that by setting the first tab 40 and the third tab 60 in the first coating area in a predetermined ratio, the electrode assembly 100 in the first embodiment can reduce the internal resistance difference between adjacent tabs, thereby effectively improving the overcurrent capability of the electrode assembly 100 and thus increasing the charging speed of the electrode assembly 100.

[0079] Table 2. Experimental results of temperature rise data As can be seen from the data in Table 2, the temperature rise of the electrode assembly 100 in the first embodiment is 4.2°C lower than that in the first comparative embodiment. This proves that by setting the first tab 40 and the third tab 60 in the first coating area in a predetermined ratio, the electrode assembly 100 in the first embodiment can effectively reduce the temperature rise of the electrode assembly 100 and improve the safety of the electrode assembly 100.

[0080] Please see Figure 25This application also provides a battery 500, which includes a housing 501 and an electrode assembly as described in any of the above embodiments, wherein the electrode assembly is disposed within the housing 501.

[0081] Please see Figure 26 This application also provides an electrical device 600, which includes a circuit element 601 and a battery 500 as described in the above embodiments. The circuit element 601 is electrically connected to the battery 500. The electrical device 600 includes, but is not limited to, electronic devices such as mobile phones, computers, and mobile terminals.

[0082] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be incorporated into the present invention.

[0083] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An electrode assembly: comprising: A first electrode plate, wherein a first electrode tab is provided on the first electrode plate; The second electrode plate has a second electrode tab. and An insulating membrane is disposed between the first electrode and the second electrode, and the first electrode, the insulating membrane, and the second electrode are wound together to form the electrode assembly; The electrode assembly is characterized in that it further includes a third tab, which is disposed on the first electrode plate; The first electrode includes a first current collector and a first active material layer. The first active material layer is disposed on the surface of the first current collector to form a first coating area. The first active material layer extends in a strip shape along a first direction. The first tab and the third tab are disposed at intervals in the first coating area. The first direction is the length direction of the first electrode in its unfolded state. Along the first direction, the first tab and the third tab divide the first coating area into a first part, a second part and a third part, and the length ratio of the first part, the second part and the third part is 1:(0.5-1.5):(0.5-1.5); Along a third direction, the projections of the first tab, the second tab, and the third tab on the surface of the electrode assembly do not overlap; wherein, the third direction is the thickness direction of the electrode assembly.

2. The electrode assembly as described in claim 1, characterized in that, The first active material layer is provided with a first groove and a third groove at intervals. The first electrode tab is disposed in the first groove and the third electrode tab is disposed in the third groove. Along the first direction, the length of the first active material layer is L and the distance between the first groove and the third groove is H, wherein |L / 2-H|≤100mm and L≥700mm. The first groove and the third groove are formed by the absence of the first active material layer.

3. The electrode assembly as described in claim 2, characterized in that, Along the second direction, the first groove penetrates the first active material layer; the second direction is the width direction of the first electrode.

4. The electrode assembly as described in claim 2, characterized in that, Along the second direction, the first edge of the first groove is flush with the first side of the first current collector, and the second edge of the first groove is spaced apart from the second side of the first current collector; wherein, the second direction is the width direction of the first electrode.

5. The electrode assembly as described in claim 2, characterized in that, Along the first direction, the side of the first electrode tab is spaced apart from the side of the first groove.

6. The electrode assembly as claimed in claim 5, characterized in that, Along the first direction, the distance between the side of the first electrode tab and the side of the first groove is 2-2.5 mm.

7. The electrode assembly as claimed in claim 5, characterized in that, Along the first direction, the width of the first tab is 6-8 mm, and the width of the first groove is 10-13 mm.

8. The electrode assembly as claimed in claim 2, characterized in that, The first electrode includes a first section and a second section. The first section is disposed in the first groove and connected to the first current collector. The second section is bent toward the side of the first current collector away from the first section.

9. The electrode assembly as claimed in claim 1, characterized in that, Along the second direction, the first current collector includes a first side and a second side disposed opposite to each other, the first electrode tab extends out of the first side, the third electrode tab extends out of the second side, and the second direction is the width direction of the first electrode sheet.

10. The electrode assembly as claimed in claim 1, characterized in that, The first tab and the second tab are formed by a portion of the side surface of the first current collector extending beyond the first current collector.

11. The electrode assembly as claimed in claim 1, characterized in that, The second electrode includes a second current collector and a second active material layer. The second active material layer is disposed on the surface of the second current collector to form a second coating area, and the second tab is disposed on the second coating area.

12. The electrode assembly as claimed in claim 11, characterized in that, The second electrode tab divides the second coating area into a fourth part and a fifth part. Along the winding direction of the second electrode sheet, the length ratio of the fourth part to the fifth part is 1:(0.5-1.5).

13. The electrode assembly as claimed in claim 11, characterized in that, The electrode assembly further includes a fourth tab, which is disposed in the second coating area and spaced apart from the second tab. The second tab and the fourth tab divide the second coating area into a fourth part, a fifth part and a sixth part. Along the winding direction of the second electrode sheet, the length ratio of the fourth part, the fifth part and the sixth part is 1:(0.5-1.5):(0.5-1.5).

14. The electrode assembly as claimed in claim 1, characterized in that, Along the third direction, there are at least two layers of the first electrode or the second electrode between adjacent electrodes.

15. A battery, characterized in that, The battery includes a housing and an electrode assembly as described in any one of claims 1-14, the electrode assembly being disposed within the housing.

16. The battery as claimed in claim 15, characterized in that, The first electrode is a cathode and the second electrode is an anode. The first electrode has a first active material layer on both sides of the current collector at the starting end of the winding, so that the starting end of the winding of the first electrode forms a double-sided area. The second electrode does not have a second active material layer on either side of the current collector at the starting end of the winding, so that the starting end of the winding of the second electrode forms an empty foil area.

17. An electrical appliance, characterized in that, The electrical device includes circuit elements and the battery as described in claim 15 or claim 16, wherein the circuit elements are electrically connected to the battery.

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