A wound electrode assembly and battery

Abstract

The application provides a winding electrode assembly and a battery. The battery comprises an anode electrode sheet and a cathode electrode sheet. A cathode starting portion is provided with a cathode starting insulating layer. A cathode ending portion is provided with a cathode ending insulating layer. A cathode active material layer is located between the cathode starting portion and the cathode ending portion. An anode active material layer is located between an anode starting portion and an anode ending portion. The starting end of the cathode starting portion is level with the starting end of the anode starting portion, and the ending end of the cathode ending portion is level with the ending end of the anode ending portion. The two ends of the anode active material layer along the winding direction respectively extend to overlap the cathode starting insulating layer and the cathode ending insulating layer. As described above, by arranging the insulating layer, the anode electrode sheet can have a lateral overhang relative to the cathode electrode sheet, and the cathode electrode sheet and the anode electrode sheet can be always aligned and overlapped during winding, thereby solving the difference in the lateral thickness of the battery cell caused by the different lengths of the cathode electrode sheet and the anode electrode sheet.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a wound electrode assembly, and also to a battery including the aforementioned wound electrode assembly. Background Technology

[0002] Today, lithium batteries are closely related to people's lives, playing an irreplaceable role in fields such as communications, automobiles, medical care, home appliances, and security. The production process of lithium batteries is relatively long, and it can be roughly divided into the front-end process (electrode manufacturing), the middle-end process (cell synthesis), and the back-end process (formation and packaging).

[0003] Winding is a crucial step in the intermediate process of lithium battery production. In the winding process of lithium battery production, in order to prevent lithium plating, the gap between the electrodes in the core must be consistent, and the anode electrode must also have lateral and longitudinal overhang specifications relative to the cathode electrode.

[0004] In actual production, during the winding process, there is one cathode electrode, one anode electrode, and two diaphragms, with the diaphragms positioned between the anode and cathode electrodes. The specific winding process is as follows: the diaphragm is wound 1-2 turns first, the anode electrode is fed in, and after the anode electrode is wound 0.1-2 turns, the cathode electrode is fed in. This method ensures that there is a lateral overhang between the anode electrode and the cathode electrode by controlling the order of feeding. However, due to the lateral overhang, there are differences in the gaps between the electrodes in the core. Utility Model Content

[0005] In view of this, the purpose of this application is to provide a wound electrode assembly and a battery, which solves the problem of differences in the gaps between the electrodes in the wound electrode assembly.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] A wound electrode assembly includes a stacked and wound anode electrode and a cathode electrode, wherein a diaphragm is disposed between the anode electrode and the cathode electrode;

[0008] The cathode current collector of the cathode electrode includes a cathode starting part and a cathode ending part arranged along the winding direction. The cathode starting part is provided with a cathode starting insulating layer; the cathode ending part is provided with a cathode ending insulating layer; and the cathode active material layer is located between the cathode starting part and the cathode ending part.

[0009] The anode current collector of the anode electrode includes an anode starting part and an anode ending part arranged along the winding direction; the anode active material layer is located between the anode starting part and the anode ending part;

[0010] The starting end of the cathode starting portion is flush with the starting end of the anode starting portion, and the ending end of the cathode terminating portion is flush with the ending end of the anode terminating portion. The two ends of the anode active material layer extend along the winding direction to overlap with the cathode starting insulating layer and the cathode terminating insulating layer, respectively.

[0011] Optionally, in the above-mentioned wound electrode assembly,

[0012] The cathode current collector includes a first surface and a second surface along the thickness direction; the cathode starting portion includes a first starting portion located on the first surface and a second starting portion located on the second surface; the cathode starting insulating layer includes a first starting insulating layer disposed on the first starting portion and a second starting insulating layer disposed on the second starting portion; the cathode terminating portion includes a first terminating portion located on the first surface and a second terminating portion located on the second surface; the cathode terminating insulating layer includes a first terminating insulating layer disposed on the first terminating portion and a second terminating insulating layer disposed on the second terminating portion;

[0013] The anode current collector includes a third surface and a fourth surface; the anode starting portion includes a third starting portion located on the third surface and a fourth starting portion located on the fourth surface; the third starting portion is provided with a third starting insulating layer, and the fourth starting portion is provided with a fourth starting insulating layer; the anode terminating portion includes a third terminating portion located on the third surface and a fourth terminating portion located on the fourth surface; the third terminating portion is provided with a third terminating insulating layer, and the fourth terminating portion is provided with a fourth terminating insulating layer; wherein:

[0014] The length of the first starting insulating layer is greater than the length of the third starting insulating layer, and the length of the second starting insulating layer is greater than the length of the fourth starting insulating layer;

[0015] The length of the first terminating insulating layer is greater than the length of the third terminating insulating layer, the length of the second terminating insulating layer is greater than the length of the fourth terminating insulating layer, and the length of the second terminating insulating layer is greater than the length of the first terminating insulating layer.

[0016] Optionally, in the above-mentioned wound electrode assembly, along the winding axis, a first end insulating layer and a second end insulating layer are respectively provided at both ends of the cathode current collector, and a cathode active material layer is provided between the first end insulating layer and the second end insulating layer; along the winding axis, an anode current collector is provided with an anode active material layer.

[0017] Along the winding axis, the two ends of the cathode current collector are level with the two ends of the anode current collector.

[0018] Optionally, in the above-mentioned wound electrode assembly, along the winding axis direction, the widths of the first end insulating layer, the cathode active material layer, and the second end insulating layer are equal to the width of the anode active material layer.

[0019] Optionally, in the above-described wound electrode assembly, the length of the first initial insulating layer is 8mm-12mm; the length of the third initial insulating layer is 4mm-6mm; and / or,

[0020] The length of the second initial insulating layer is 8mm-12mm; the length of the fourth initial insulating layer is 4mm-6mm.

[0021] Optionally, in the above-mentioned wound electrode assembly, the length of the first terminating insulating layer is 8mm-12mm; the length of the third terminating insulating layer is 4mm-6mm; and / or,

[0022] Along the winding from the starting end to the ending end, the cathode current collector is sequentially connected with n cathode tabs at intervals. The distance between the (n-1)th cathode tab and the nth cathode tab is Dn-1. The length of the second termination insulating layer is L, where Dn-1+8mm≤L≤Dn-1+12mm. The length of the fourth termination insulating layer is 4mm-6mm.

[0023] Optionally, in the above-mentioned wound electrode assembly, along the winding axis: the width of the first end insulating layer is 1.2mm-1.8mm; and / or,

[0024] The width of the second end insulating layer is 1.2mm-1.8mm.

[0025] Optionally, in the above-mentioned wound electrode assembly, the diaphragm includes a first diaphragm and a second diaphragm, and the anode electrode, the first diaphragm, the cathode electrode, and the second diaphragm are sequentially stacked and wound from the inside out; wherein:

[0026] The starting ends of the first and second diaphragms are flush with the starting ends of the anode and cathode electrodes, and the starting ends of the winding are located at the junction of the bent and straight sections of the wound electrode assembly; and / or,

[0027] The termination ends of the first diaphragm and the second diaphragm are flush with the termination ends of the anode electrode and the cathode electrode, and the termination ends of the winding are located in the bending section of the wound electrode assembly.

[0028] Optionally, in the above-mentioned wound electrode assembly, the thickness of the cathode insulating layer is equal to the thickness of the cathode active material layer;

[0029] The thickness of the anode insulating layer is equal to the thickness of the anode active material layer.

[0030] A battery comprising a wound electrode assembly as described above.

[0031] In the wound electrode assembly, battery, and electrical device of this application, the cathode current collector of the cathode electrode includes a wound cathode starting portion and a cathode ending portion, with a cathode starting insulating layer provided in the cathode starting portion and a cathode ending insulating layer provided in the cathode ending portion; the anode current collector of the anode electrode includes a wound anode starting portion and an anode ending portion, with an anode active material layer provided between the anode starting portion and the anode ending portion; and it is ensured that the starting end of the cathode starting portion is flush with the starting end of the cathode starting portion, the ending end of the cathode ending portion is flush with the ending end of the anode ending portion, and the two ends of the anode active material layer extend along the winding direction to overlap with the cathode starting insulating layer and the cathode ending insulating layer, respectively; as described above, by providing a cathode starting insulating layer and a cathode ending insulating layer, and by having the two ends of the anode active material layer extend along the winding direction to overlap with the cathode starting insulating layer and the cathode ending insulating layer, the cathode active material layer is effectively integrated into the device. The overlapping of the starting insulating layer and the cathode terminating insulating layer ensures that, on the one hand, the two ends of the anode electrode along the winding direction satisfy the lateral overhang (i.e., there is an excess area between the two ends of the anode active material layer along the winding direction and the two ends of the cathode active material layer along the winding direction), while also ensuring that the cathode and anode electrodes are always aligned and overlapped during winding. That is, the starting end of the cathode starting part is level with the starting end of the cathode starting part, and the terminating end of the cathode terminating part is level with the terminating end of the anode terminating part. This solves the problem of lateral thickness difference in the cell caused by the different lengths of the cathode and anode electrodes, and prevents lithium plating. On the other hand, even if the electrode tip swings during winding, the presence of the insulating layer can accommodate the dimensional deviation caused by the tip swinging and prevent short circuits. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the structure of the first side of the cathode electrode sheet before die-cutting, according to an embodiment of this application.

[0034] Figure 2 for Figure 1 A schematic diagram of the structure of the die-cut cathode electrode;

[0035] Figure 3 This is a schematic diagram of the second side of the cathode electrode sheet before die-cutting, according to an embodiment of this application.

[0036] Figure 4 for Figure 3 A schematic diagram of the structure of the die-cut cathode electrode;

[0037] Figure 5 This is a schematic diagram of the third (fourth) side of the anode sheet before die-cutting, according to an embodiment of this application.

[0038] Figure 6 for Figure 5 Schematic diagram of the die-cut anode sheet;

[0039] Figure 7 A schematic diagram showing the structure of individual cathode and anode electrodes after being converted into a stacked structure;

[0040] Figure 8 This is a schematic diagram of the structure of the wound electrode assembly according to an embodiment of this application.

[0041] superior Figures 1-8 middle:

[0042] 1. Anode plate; 2. First diaphragm; 3. Cathode plate; 4. Second diaphragm; 5. Anode tab; 6. Cathode tab;

[0043] 11. Third starting insulation layer; 12. Third ending insulation layer; 13. Fourth starting insulation layer; 14. Fourth ending insulation layer;

[0044] 31. First starting insulating layer; 32. First ending insulating layer; 33. Second starting insulating layer; 34. Second ending insulating layer; 35. First end insulating layer; 36. Second end insulating layer. Detailed Implementation

[0045] This application provides a wound electrode assembly and a battery. By setting a cathode starting insulating layer and a cathode ending insulating layer, it ensures that there is a lateral overhang at both ends of the anode electrode relative to the cathode electrode (i.e., there is an excess area at both ends of the anode active material layer relative to both ends of the cathode active material layer along the winding direction), while also ensuring that the cathode electrode and the anode electrode are always aligned and overlapped during winding. This solves the problem of the difference in lateral thickness of the cell caused by the different lengths of the cathode electrode and the anode electrode.

[0046] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] like Figures 1-8As shown in the figure, this application provides a wound electrode assembly, which includes a stacked and wound anode electrode 1 and a cathode electrode 3, with a diaphragm disposed between the anode electrode 1 and the cathode electrode 3. The cathode current collector of the cathode electrode 3 includes a cathode starting portion and a cathode ending portion disposed along the winding direction. The cathode starting portion is provided with a cathode starting insulating layer; the cathode ending portion is provided with a cathode ending insulating layer. The cathode active material layer is located between the cathode starting portion and the cathode ending portion. The anode current collector of the anode electrode 1 includes an anode starting portion and an anode ending portion disposed along the winding direction; the anode active material layer is located between the anode starting portion and the anode ending portion. The starting end of the cathode starting portion is flush with the starting end of the anode starting portion, and the ending end of the cathode ending portion is flush with the ending end of the anode ending portion. The two ends of the anode active material layer extend along the winding direction to overlap with the cathode starting insulating layer and the cathode ending insulating layer, respectively.

[0048] It should be noted that the wound electrode assembly can be simply referred to as the core, and the "core" mentioned below also refers to the wound electrode assembly. The winding direction refers to the direction in which the stacked anode electrode 1, cathode electrode 3, and diaphragm rotate around the winding needle. The feeding direction of the winding is parallel to the length direction of both the cathode electrode 3 and the anode electrode 1. The cathode current collector includes a cathode starting section and a cathode ending section arranged along the winding direction; that is, when the cathode current collector is unfolded to be parallel to its length direction, the two ends of the cathode current collector along its length direction are the cathode starting section and the cathode ending section, respectively. The cathode starting section is the beginning position of the winding; the cathode ending section is the ending position of the winding. Similarly, the anode current collector includes an anode starting section and an anode ending section arranged along the winding direction; that is, when the anode current collector is unfolded to be parallel to its length direction, the two ends of the anode current collector along its length direction are the anode starting section and the anode ending section, respectively. The anode starting section is the beginning position of the winding; the anode ending section is the ending position of the winding.

[0049] Furthermore, the transverse direction of the cell, or the transverse direction of the wound electrode assembly, is parallel to the length direction of the unfolded electrode sheet. The longitudinal direction of the cell, or the longitudinal direction of the wound electrode assembly, is parallel to the direction of the winding axis; the winding axis direction refers to the direction of the axis along which the winding needle is located when the electrode sheet rotates around the winding needle, and the winding axis direction is parallel to the width direction of the electrode sheet.

[0050] The starting end of the cathode initiation portion is the end of the cathode initiation portion that is furthest from the cathode termination portion. The terminating end of the cathode termination portion is the end of the cathode termination portion that is furthest from the cathode initiation portion. The anode initiation portion may not have an extension length, in which case the starting end of the anode initiation portion is the anode initiation portion itself; the anode initiation portion may have an extension length, in which case the starting end of the anode initiation portion is the end of the anode initiation portion that is furthest from the anode termination portion. The anode termination portion may not have an extension length, in which case the terminating end of the anode termination portion is the anode termination portion itself; the anode termination portion may have an extension length, in which case the terminating end of the anode termination portion is the end of the anode termination portion that is furthest from the anode initiation portion.

[0051] It should be further explained that the cathode active material layer can be applied to the cathode current collector using either a wet or dry process. Optionally, the cathode active material layer can be coated onto the cathode current collector using a wet process. Specifically, the cathode active material, conductive agent, binder, and other raw materials are mixed to form a cathode active material slurry, which is then uniformly coated onto the surface of the cathode current collector using a coating device. The slurry is then dried and rolled to form the cathode active material layer. Similarly, the anode active material layer can be applied to the anode current collector using either a wet or dry process. Optionally, the cathode initial insulating layer can be any one of a ceramic insulating layer, a polymer insulating layer, or a composite insulating layer. The cathode initial insulating layer can be applied to the cathode current collector using either a wet or dry process. Optionally, the anode initial insulating layer can be any one of a ceramic insulating layer, a polymer insulating layer, or a composite insulating layer. The anode initial insulating layer can be applied to the anode current collector using either a wet or dry process.

[0052] In the wound electrode assembly of this application embodiment, a cathode starting insulating layer is provided at the cathode starting portion and a cathode ending insulating layer is provided at the cathode ending portion. It is ensured that the starting end of the cathode starting portion is flush with the starting end of the cathode starting portion, and the ending end of the cathode ending portion is flush with the ending end of the anode ending portion (i.e., both ends of the cathode electrode 3 and the anode electrode 1 are flush along the winding direction). Furthermore, the two ends of the anode active material layer along the winding direction extend to overlap with the cathode starting insulating layer and the cathode ending insulating layer, respectively. As described above, by providing the cathode starting insulating layer and the cathode ending insulating layer, while ensuring that there is an excess region between the two ends of the anode active material layer along the winding direction relative to the two ends of the cathode active material layer along the winding direction (i.e., there is a lateral overhang between the two ends of the anode electrode along the winding direction relative to the cathode electrode), lithium plating is prevented. At the same time, it eliminates the need for a related correction system to maintain the lateral overhang of the electrode, ensuring that the cathode electrode 3 and the anode electrode 1 are always aligned and overlapped during winding, guaranteeing the thickness consistency between the cathode electrode 3 and the anode electrode 1, and solving the problem of lateral thickness differences in the battery cell caused by the different lengths of the cathode electrode 3 and the anode electrode 1. The wound electrode assembly, once formed by hot pressing, no longer produces gaps, ensuring consistent compaction and improving subsequent lithium plating.

[0053] Furthermore, insulating layers are provided at the cathode start and cathode end portions along the winding direction of the cathode current collector. This can cover the cutting burrs at the start and end of the winding, avoiding powder shedding during the winding process and the risk of short circuits in the battery cell caused by burrs piercing the diaphragm.

[0054] For further details, please refer to [link / reference]. Figures 1-4 The cathode active material layer is coated onto the aluminum foil intermittently, and a cathode insulating layer is coated between adjacent cathode active material layers. Through continuous winding, under the premise of intermittent coating, the cathode insulating layer is cut in one stroke, thus dividing it into: the cathode termination insulating layer of the just-wound cathode electrode 3 and the cathode start insulating layer of the next cathode electrode 3 to be wound. Since the ends of the cathode electrode 3 and the anode electrode 1 are flush along the winding direction, the unwinding strips of the cathode electrode and the anode electrode can be cut in one stroke to simultaneously obtain the wound cathode electrode 3 and the anode electrode 1, improving winding efficiency and preventing electrode tailing defects. The cathode electrode 3 includes a cathode tab 6; the aluminum foil includes a cathode current collector with various functional layers (including the cathode active material layer and various insulating layers), and an empty foil area located at the end of the cathode current collector along the winding axis. The cathode tab 6, integrally connected to the cathode current collector, is obtained by cutting the empty foil area.

[0055] Please see Figures 1-4In some embodiments of this application, the cathode current collector includes a first surface and a second surface along the thickness direction; the first surface is the cathode A surface, and the second surface is the cathode B surface. The cathode starting portion includes a first starting portion located on the first surface and a second starting portion located on the second surface; the cathode starting insulating layer includes a first starting insulating layer 31 disposed on the first starting portion and a second starting insulating layer 33 disposed on the second starting portion. The cathode terminating portion includes a first terminating portion located on the first surface and a second terminating portion located on the second surface; the cathode terminating insulating layer includes a first terminating insulating layer 32 disposed on the first terminating portion and a second terminating insulating layer 34 disposed on the second terminating portion.

[0056] Please see Figures 5-6 The anode current collector includes a third surface and a fourth surface; the third surface is the anode A surface, and the fourth surface is the anode B surface. The anode starting portion includes a third starting portion located on the third surface and a fourth starting portion located on the fourth surface; the third starting portion is provided with a third starting insulating layer 11, and the fourth starting portion is provided with a fourth starting insulating layer 13. The anode terminating portion includes a third terminating portion located on the third surface and a fourth terminating portion located on the fourth surface; the third terminating portion is provided with a third terminating insulating layer 12, and the fourth terminating portion is provided with a fourth terminating insulating layer 14.

[0057] The length of the first starting insulating layer 31 is greater than the length of the third starting insulating layer 11, and the length of the second starting insulating layer 33 is greater than the length of the fourth starting insulating layer 13. The length of the first terminating insulating layer 32 is greater than the length of the third terminating insulating layer 12, and the length of the second terminating insulating layer 34 is greater than the length of the fourth terminating insulating layer 14, and the length of the second terminating insulating layer 34 is greater than the length of the first terminating insulating layer 32.

[0058] It should be noted that at least one of the first starting insulating layer 31, the first ending insulating layer 32, the second starting insulating layer 33, the second ending insulating layer 34, the third starting insulating layer 11, the third ending insulating layer 12, the fourth starting insulating layer 13, and the fourth ending insulating layer 14 can be any one of ceramic insulating layer, polymer insulating layer, composite insulating layer, etc.; preferably, all of them are ceramic insulating layers.

[0059] The second side of the cathode electrode 3 with the second terminating insulating layer 34 is disposed opposite to the anode electrode 1; the second terminating insulating layer 34 is located at the outermost periphery of the wound electrode assembly. Optionally, the second terminating insulating layer 34 covers at least one ring around the outermost periphery of the wound electrode assembly; for example, the second terminating insulating layer 34 covers the outermost periphery of the wound electrode assembly.

[0060] Since the starting end of the first starting insulating layer 31 is flush with the starting end of the third starting insulating layer 11, and the length of the first starting insulating layer 31 is greater than the length of the third starting insulating layer 11, it is inevitable that on the side near the starting end of winding, the cathode active material layer is shorter than the anode active material layer, and the anode active material layer has an area overlapping with the first starting insulating layer 31. That is, there is an excess area of ​​the anode active material layer relative to the cathode active material layer, in order to meet the design requirements of the battery cell. Similarly, since the starting end of the second starting insulating layer 33 is flush with the starting end of the fourth starting insulating layer 13, and the length of the second starting insulating layer 33 is greater than the length of the fourth starting insulating layer 13, it is inevitable that on the side near the starting end of winding, the length of the cathode active material layer is shorter than the length of the anode active material layer, and the anode active material layer has an area overlapping with the second starting insulating layer 33. That is, there is an excess area of ​​the anode active material layer relative to the cathode active material layer, in order to meet the design requirements of the battery cell.

[0061] Similarly, since the termination end of the first termination insulating layer 32 is flush with the termination end of the third termination insulating layer 12, and the length of the first termination insulating layer 32 is greater than the length of the third termination insulating layer 12, it will inevitably result in the following on the side near the winding termination end: the cathode active material layer is shorter than the anode active material layer, and the anode active material layer has an area overlapping with the first termination insulating layer 32, that is, the anode active material layer has an excess area relative to the cathode active material layer, in order to meet the design requirements of the battery cell. Similarly, since the termination end of the second termination insulating layer 34 is flush with the termination end of the fourth termination insulating layer 14, and the length of the second termination insulating layer 34 is greater than the length of the fourth termination insulating layer 14, it will inevitably result in the following on the side near the winding termination end: the length of the cathode active material layer is shorter than the length of the anode active material layer, and the anode active material layer has an area overlapping with the second termination insulating layer 34, that is, the anode active material layer has an excess area relative to the cathode active material layer, in order to meet the design requirements of the battery cell.

[0062] Since the second termination insulating layer 34 of the cathode electrode 3 serves as the finishing structure of the wound electrode assembly, and the anode electrode 1 does not have a region with its surface facing the second termination portion of the cathode electrode 3, the second termination portion does not need to have a cathode active material layer opposite to the anode active material layer. Therefore, the second termination insulating layer 34 is provided in the second termination portion to supplement the thickness and ensure the consistency of the lateral thickness of the battery cell. Furthermore, the second termination insulating layer 34 covers at least one turn of the wound electrode assembly, which precisely serves as insulation protection to prevent short circuits with the housing.

[0063] Furthermore, insulating layers are provided at the anode start and anode end of the anode current collector along the winding direction, which can cover the cutting burrs at the start and end of the winding, avoiding powder shedding during the winding process and the risk of short circuit of the cell caused by burrs piercing the diaphragm.

[0064] For further details, please refer to [link / reference]. Figures 5-6 An anodic active material layer is intermittently coated onto a copper foil, and an anodic insulating layer is coated between adjacent anodic active material layers. Using a continuous winding method, while intermittently coating, the anodic insulating layer is cut in one stroke, thus dividing it into: the anodic termination insulating layer of the just-wound anodic electrode 1 and the anodic starting insulating layer of the next anodic electrode 1 to be wound. The anodic electrode 1 includes an anodic tab 5; the copper foil includes an anodic current collector with various functional layers (including an anodic active material layer and various insulating layers), and an empty foil area located at the end of the cathode current collector along the winding axis. The anodic tab 5, integrally connected to the anodic current collector, is obtained by cutting the empty foil area.

[0065] Please see Figures 2-4 In some embodiments of this application, along the winding axis, a first end insulating layer 35 and a second end insulating layer 36 are respectively provided at both ends of the cathode current collector, and a cathode active material layer is provided between the first end insulating layer 35 and the second end insulating layer 36. Along the winding axis, an anode current collector is provided with an anode active material layer. Along the winding axis, both ends of the cathode current collector are flush with both ends of the anode current collector.

[0066] It should be noted that, along the winding axis, the first and second surfaces of the cathode electrode 3 are provided with a first end insulating layer 35 and a second end insulating layer 36, and the arrangement of the first and second surfaces is consistent.

[0067] The original wound electrode assembly structure: In order to maintain longitudinal overhang, the width of the anode electrode is greater than that of the cathode electrode at both ends along the winding axis, and the two are not aligned. However, the wound electrode assembly of this application: By setting the first end insulating layer 35 and the second end insulating layer 36, while ensuring that there is an excess area at both ends of the anode active material layer along the winding axis relative to the two ends of the cathode active material layer along the winding axis (i.e., there is longitudinal overhang at both ends of the anode electrode along the winding axis relative to the cathode electrode) to prevent lithium plating, it can ensure that the cathode electrode 3 and the anode electrode 1 are aligned in the longitudinal direction (i.e., the electrode width direction) and are always overlapped and wound, without the need for a related correction system to maintain the longitudinal overhang of the electrode. This solves the problem of the difference in longitudinal thickness of the cell caused by the different widths of the cathode electrode 3 and the anode electrode 1.

[0068] Please see Figure 7 In some embodiments of this application, along the winding axis direction, the widths of the first end insulating layer 35, the cathode active material layer, and the second end insulating layer 36 are equal to the width of the anode active material layer.

[0069] As shown above, the sum of the widths of the first end insulating layer 35, the cathode active material layer, and the second end insulating layer 36 in the cathode current collector equals the width of the anode active material layer in the anode current collector, ensuring that there are no gap areas between the cathode current collector and the anode current collector along the winding axis, thus avoiding longitudinal thickness differences in the battery cell.

[0070] In some embodiments of this application, the length of the third starting insulating layer 11 is 4mm-6mm; for example, the length of the third starting insulating layer 11 can be any one of 4mm, 4.5mm, 5mm, 5.5mm, 6mm, etc.

[0071] As shown above, the length of the third initial insulating layer 11 is limited to a suitable range, which avoids the disadvantages of being too short and not being able to effectively prevent powder shedding and cover cutting burrs, and also avoids the disadvantages of being too long and occupying too large anode current collector size, thus affecting the volumetric energy density of the battery.

[0072] Furthermore, the length of the first initial insulating layer 31 is 8mm-12mm; for example, the length of the first initial insulating layer 31 can be any one of 8mm, 9mm, 10mm, 11mm, 12mm, etc.

[0073] As shown above, the length of the first starting insulating layer 31 is limited to a suitable range. Its length is matched with that of the third starting insulating layer 11. This not only ensures that the length of the first starting insulating layer 31 is greater than that of the third starting insulating layer 11, but also avoids the disadvantage that the length of the first starting insulating layer 31 is too short and cannot meet the performance requirements of the starting part Overhang (hereinafter referred to as the starting part OH). It also avoids the disadvantage that the length of the first starting insulating layer 31 is too long and occupies too much space in the cathode current collector, thus affecting the volumetric energy density of the cell.

[0074] In some embodiments, the length of the fourth starting insulating layer 13 is 4mm-6mm; for example, the length of the fourth starting insulating layer 13 can be any one of 4mm, 4.5mm, 5mm, 5.5mm, 6mm, etc.

[0075] As shown above, the length of the fourth initial insulating layer 13 is limited to a suitable range, which avoids the disadvantages of being too short and not being able to effectively prevent powder shedding and cover cutting burrs, and also avoids the disadvantages of being too long and occupying too large anode current collector size, thus affecting the volumetric energy density of the battery.

[0076] Furthermore, the length of the second initial insulating layer 33 is 8mm-12mm; for example, the length of the second initial insulating layer 33 can be any one of 8mm, 9mm, 10mm, 11mm, 12mm, etc.

[0077] As described above, the length of the second starting insulating layer 33 is limited to a suitable range. Its length is matched with that of the fourth starting insulating layer 13. This not only ensures that the length of the second starting insulating layer 33 is greater than that of the fourth starting insulating layer 13, but also avoids the disadvantage that the length of the second starting insulating layer 33 is too short and cannot meet the performance requirements of the starting part Overhang (hereinafter referred to as the starting part OH). It also avoids the disadvantage that the length of the second starting insulating layer 33 is too long and occupies too much space in the cathode current collector, thus affecting the volumetric energy density of the cell.

[0078] In some embodiments of this application, the length of the third terminating insulating layer 12 is 4mm-6mm; for example, the length of the third terminating insulating layer 12 can be any one of 4mm, 4.5mm, 5mm, 5.5mm, 6mm, etc.

[0079] As shown above, the length of the third termination insulation layer 12 is limited to a suitable range, which avoids the disadvantages of being too short and not being able to effectively prevent powder shedding and cover cutting burrs, and also avoids the disadvantages of being too long and occupying too large anode current collector size, thus affecting the volumetric energy density of the battery.

[0080] Furthermore, the length of the first termination insulation layer 32 is 8mm-12mm; for example, the length of the first termination insulation layer 32 can be any one of 8mm, 9mm, 10mm, 11mm, 12mm, etc.

[0081] As described above, the length of the first termination insulating layer 32 is limited to a suitable range. Its length is matched with that of the third termination insulating layer 12. This not only ensures that the length of the first termination insulating layer 32 is greater than that of the third termination insulating layer 12, but also avoids the disadvantage that the length of the first termination insulating layer 32 is too short and cannot meet the performance requirements of the termination part Overhang (hereinafter referred to as the termination part OH). It also avoids the disadvantage that the length of the first termination insulating layer 32 is too long and occupies too much space in the cathode current collector, thus affecting the volumetric energy density of the cell.

[0082] In some embodiments, the length of the fourth terminating insulating layer 14 is 4mm-6mm; for example, the length of the fourth terminating insulating layer 14 can be any one of 4mm, 4.5mm, 5mm, 5.5mm, 6mm, etc.

[0083] As shown above, the length of the fourth termination insulating layer 14 is limited to a suitable range, which avoids the disadvantage of being too short to cover the cutting burrs well, and also avoids the disadvantage of being too long to occupy too large anode current collector size, thus affecting the volumetric energy density of the battery.

[0084] Please see Figure 2 , Figure 4In some embodiments, along the starting end to the ending end of the winding, the cathode current collector is sequentially connected with n cathode tabs 6 at intervals, the distance between the (n-1)th cathode tab 6 and the nth cathode tab 6 is Dn-1, and the length of the second termination insulating layer 34 is L, Dn-1+8mm≤L≤Dn-1+12mm; for example, the length of the second termination insulating layer 34 can be any one of Dn-1+8mm, Dn-1+9mm, Dn-1+10mm, Dn-1+11mm, Dn-1+12mm, etc.

[0085] Dn-1 is the distance between the (n-1)th cathode tab 6 and the nth cathode tab 6, which is approximately the length of the outermost ring of the coiled electrode assembly. By limiting the length of the second terminating insulating layer 34 within the above range, the disadvantage of being too short to cover the outermost ring of the coiled electrode assembly is avoided, while the disadvantage of being too long and occupying too large a size of the cathode current collector, thus affecting the volumetric energy density of the battery, is also avoided.

[0086] It should be noted that, along the winding direction, since the two ends of the cathode electrode 3 and anode electrode 1 of the wound electrode assembly are flat, but the length of each coil of the coiled electrode assembly is different from the inner to the outer coil (this is because the thickness of the coiled electrode assembly changes during the winding process, and the outermost coils naturally have a length difference relative to the inner coils due to the thickness), there is a difference in length between the unfolded cathode electrode 3 and anode electrode 1. The unfolded length of the outer cathode electrode 3, i.e., the total length of the cathode electrode, is b, and the unfolded length of the inner anode electrode 1, i.e., the total length of the anode electrode, is a. b > a, and the length difference between the two is ba.

[0087] In some embodiments of this application, the width of the first end insulating layer 35 along the winding axis is 1.2mm-1.8mm; optionally, the width of the first end insulating layer 35 can be any one of 1.2mm, 1.3mm, 1.5mm, 1.7mm, 1.8mm, etc.

[0088] Along the winding axis, the end of the cathode current collector closest to the cathode tab is the top, and the end furthest from the cathode tab is the bottom. A first insulating layer 35 is disposed on the top of the cathode current collector, capable of covering the burrs formed by cutting the cathode tab 6. The width of the first insulating layer 35 is limited to a suitable range, avoiding the drawback of being too narrow to meet the top overhang (top OH) performance requirements, and also avoiding the drawback of being too wide, resulting in excessively large space occupied by the cathode current collector and affecting the volumetric energy density of the battery.

[0089] Furthermore, along the winding axis, the width of the second end insulating layer 36 is 1.2mm-1.8mm; optionally, the width of the second end insulating layer 36 can be any one of 1.2mm, 1.3mm, 1.5mm, 1.7mm, 1.8mm, etc.

[0090] The width of the second insulating layer 36 is limited to a suitable range, avoiding the disadvantage of being too narrow to meet the performance requirements of the bottom overhang (hereinafter referred to as bottom OH), and also avoiding the disadvantage of being too wide to occupy too large a size of the cathode current collector, thus affecting the volumetric energy density of the battery.

[0091] Please see Figure 8 In some embodiments of this application, the diaphragm includes a first diaphragm 2 and a second diaphragm 4; the anode electrode 1, the first diaphragm 2, the cathode electrode 3, and the second diaphragm 4 are stacked and wound sequentially from the inside to the outside. The starting ends of the winding of the first diaphragm 2 and the second diaphragm 4 are flush with the starting ends of the winding of the anode electrode 1 and the cathode electrode 3, and the starting ends of the winding are located at the junction of the bent section and the straight section of the wound electrode assembly.

[0092] Furthermore, the termination ends of the first diaphragm 2 and the second diaphragm 4 are flush with the termination ends of the anode electrode 1 and the cathode electrode 3, and the termination ends of the winding are located in the bending section of the wound electrode assembly.

[0093] After winding, the anode electrode 1, the first diaphragm 2, the cathode electrode 3, and the second diaphragm 4 are aligned and cut in one cut to ensure that the cathode tail and the anode tail are rolled together to the bending section at the tail. The other end after cutting is the starting end of the cathode starting part and the starting end of the anode starting part, which is the winding feed end of the next winding electrode assembly to be wound. After the feeding begins, the bending section and the straight section at the feeding point are rolled together.

[0094] As shown above, by using a single cut, it is possible to precisely ensure that the end and beginning of the winding of each material are flat, greatly improving winding efficiency and preventing electrode tailing defects. Furthermore, the winding termination point is located at the bending section of the wound electrode assembly, ensuring that each material is finished at the bending section. This avoids the drawback of finishing at the flat section, which results in thickness differences between the finishing and non-finishing areas of the material in the flat section, thus improving the thickness consistency of the entire wound electrode assembly.

[0095] In some embodiments of this application, the thickness of the cathode insulating layer is equal to the thickness of the cathode active material layer. The thickness of the anode insulating layer is equal to the thickness of the anode active material layer.

[0096] The above ensures the consistency of the surface thickness of the entire cathode electrode 3 and the entire anode electrode 1, reliably guaranteeing the thickness consistency of the wound electrode assembly.

[0097] In summary, this application also provides a battery that includes the wound electrode assembly as described above.

[0098] Since the battery of this application includes the electrode assembly described above, the beneficial effects of the battery brought by the electrode assembly can be found above, and will not be repeated here.

[0099] The battery can be a rechargeable battery, which refers to a battery that can be recharged after discharge to activate the active materials and continue to be used. The battery can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and this application does not limit this. As an example, the battery can be a cylindrical battery, a prismatic battery, a pouch battery, or a battery of other shapes. Prismatic batteries include prismatic batteries, blade-shaped batteries, and multi-prismatic batteries, such as hexagonal prismatic batteries, etc., and this application does not have any particular limitations. Preferably, the battery is a lithium-ion battery, and the battery is a blade-shaped battery.

[0100] In summary, this application also provides a battery pack, which includes at least one battery as described above. A battery pack refers to a single physical module comprising one or more batteries to provide higher voltage and capacity. Multiple battery packs are arranged and fixed to form a battery module.

[0101] In summary, this application also provides an electrical device that includes the battery as described above.

[0102] Since the electrical device of this application includes the battery as described above, the beneficial effects of the battery on the electrical device are described above and will not be repeated here.

[0103] Batteries or battery packs power electrical devices. These devices can take many forms, such as automobiles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools. Automobiles can be gasoline-powered, natural gas-powered, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles. Spacecraft include airplanes, rockets, space shuttles, and spacecraft. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys. Power tools include metal-cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers. This document does not impose any special restrictions on the aforementioned electrical devices.

[0104] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not restrict this application from necessarily using the aforementioned specific details for implementation.

[0105] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0106] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0107] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0108] It should be understood that the qualifiers “first,” “second,” “third,” “fourth,” “fifth,” and “sixth” used in the description of the embodiments of this application are only used to more clearly illustrate the technical solutions and are not intended to limit the scope of protection of this application.

[0109] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A wound electrode assembly, characterized in that, It includes anode plates and cathode plates that are stacked and wound together, with a diaphragm disposed between the anode plates and the cathode plates; The cathode current collector of the cathode electrode includes a cathode starting part and a cathode ending part arranged along the winding direction. The cathode starting part is provided with a cathode starting insulating layer; the cathode ending part is provided with a cathode ending insulating layer; and the cathode active material layer is located between the cathode starting part and the cathode ending part. The anode current collector of the anode electrode includes an anode starting part and an anode ending part arranged along the winding direction; the anode active material layer is located between the anode starting part and the anode ending part; The starting end of the cathode starting portion is flush with the starting end of the anode starting portion, and the ending end of the cathode terminating portion is flush with the ending end of the anode terminating portion. The two ends of the anode active material layer extend along the winding direction to overlap with the cathode starting insulating layer and the cathode terminating insulating layer, respectively.

2. The wound electrode assembly according to claim 1, characterized in that, The cathode current collector includes a first surface and a second surface along the thickness direction; the cathode starting portion includes a first starting portion located on the first surface and a second starting portion located on the second surface; the cathode starting insulating layer includes a first starting insulating layer disposed on the first starting portion and a second starting insulating layer disposed on the second starting portion; the cathode terminating portion includes a first terminating portion located on the first surface and a second terminating portion located on the second surface; the cathode terminating insulating layer includes a first terminating insulating layer disposed on the first terminating portion and a second terminating insulating layer disposed on the second terminating portion; The anode current collector includes a third surface and a fourth surface; the anode starting portion includes a third starting portion located on the third surface and a fourth starting portion located on the fourth surface; the third starting portion is provided with a third starting insulating layer, and the fourth starting portion is provided with a fourth starting insulating layer; the anode terminating portion includes a third terminating portion located on the third surface and a fourth terminating portion located on the fourth surface; the third terminating portion is provided with a third terminating insulating layer, and the fourth terminating portion is provided with a fourth terminating insulating layer; wherein: The length of the first starting insulating layer is greater than the length of the third starting insulating layer, and the length of the second starting insulating layer is greater than the length of the fourth starting insulating layer; The length of the first terminating insulating layer is greater than the length of the third terminating insulating layer, the length of the second terminating insulating layer is greater than the length of the fourth terminating insulating layer, and the length of the second terminating insulating layer is greater than the length of the first terminating insulating layer.

3. The wound electrode assembly according to claim 1, characterized in that, Along the winding axis, a first end insulating layer and a second end insulating layer are respectively provided at both ends of the cathode current collector, and a cathode active material layer is provided between the first end insulating layer and the second end insulating layer; along the winding axis, an anode current collector is provided with an anode active material layer. Along the winding axis, the two ends of the cathode current collector are level with the two ends of the anode current collector.

4. The wound electrode assembly according to claim 3, characterized in that, Along the winding axis, the widths of the first end insulating layer, the cathode active material layer, and the second end insulating layer are equal to the width of the anode active material layer.

5. The wound electrode assembly according to claim 2, characterized in that, The length of the first initial insulating layer is 8mm-12mm; the length of the third initial insulating layer is 4mm-6mm; and / or, The length of the second initial insulating layer is 8mm-12mm; the length of the fourth initial insulating layer is 4mm-6mm.

6. The wound electrode assembly according to claim 2, characterized in that, The length of the first terminating insulating layer is 8mm-12mm; the length of the third terminating insulating layer is 4mm-6mm; and / or, Along the winding from the starting end to the ending end, the cathode current collector is sequentially connected with n cathode tabs at intervals. The distance between the (n-1)th cathode tab and the nth cathode tab is Dn-1. The length of the second termination insulating layer is L, where Dn-1+8mm≤L≤Dn-1+12mm. The length of the fourth termination insulating layer is 4mm-6mm.

7. The wound electrode assembly according to claim 3, characterized in that, Along the winding axis: the width of the first end insulating layer is 1.2mm-1.8mm; and / or, The width of the second end insulating layer is 1.2mm-1.8mm.

8. The wound electrode assembly according to claim 1, characterized in that, The diaphragm includes a first diaphragm and a second diaphragm, wherein the anode electrode, the first diaphragm, the cathode electrode, and the second diaphragm are stacked and wound sequentially from the inside out; wherein: The starting ends of the first and second diaphragms are flush with the starting ends of the anode and cathode electrodes, and the starting ends of the winding are located at the junction of the bent and straight sections of the wound electrode assembly; and / or, The termination ends of the first diaphragm and the second diaphragm are flush with the termination ends of the anode electrode and the cathode electrode, and the termination ends of the winding are located in the bending section of the wound electrode assembly.

9. The wound electrode assembly according to any one of claims 1-8, characterized in that, The thickness of the cathode insulating layer is equal to the thickness of the cathode active material layer; The thickness of the anode insulating layer is equal to the thickness of the anode active material layer.

10. A battery, characterized in that, Includes the wound electrode assembly as described in any one of claims 1-9.

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