Wound electrode assembly, battery cell, battery, and power receiving device

Abstract

The present invention provides a wound electrode assembly (22), a battery cell (20), a battery (100), a power receiving device, and a method and device (2000) for manufacturing a battery cell, and relates to the technical field of batteries. The wound electrode assembly (22) includes a positive electrode sheet (223). The positive electrode sheet (223) includes a positive electrode winding start segment (2232) that is not provided with a connected positive electrode tab (2231) and a positive electrode winding extension segment (2233) that is provided with a positive electrode tab (2231). The positive electrode winding start segment (2232) is wound at least one turn.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and specifically to a wound electrode assembly, a battery cell, a battery, an electricity receiving device, a method for manufacturing a battery cell, and a device.

Background Art

[0002] Currently, due to the rapid development of smartphones, tablets, electric vehicles, etc., the application of lithium-ion batteries is also expanding day by day, so the needs for lithium-ion batteries are increasing more and more.

[0003] While people attach importance to the safety performance of batteries, they are also demanding better electrical performance for lithium batteries. Lithium precipitation is one of the main factors affecting the electrical performance and safety performance of batteries. When lithium precipitation occurs in a cell, not only does the electrical performance of the battery decrease, but dendrites are likely to be formed as the amount of lithium precipitation accumulates, and the dendrites may break through the separator, causing a short circuit inside the battery and posing a safety concern.

[0004] Therefore, how to effectively avoid or reduce the risk of lithium precipitation in batteries has become an urgent technical problem to be solved currently. Summary of the Invention

[0005] Embodiments of this application provide a wound electrode assembly, a battery cell, a battery, an electricity receiving device, a method for manufacturing a battery cell, and a device so as to reduce the risk of lithium precipitation occurring in the electrode assembly.

[0006] According to a first aspect, embodiments of this application provide a wound electrode assembly including a positive electrode sheet. The positive electrode sheet includes a positive electrode winding start segment without a connected positive electrode tab and a positive electrode winding extending segment with the positive electrode tab provided. The positive electrode winding start segment is wound at least one turn.

[0007] In the above technical solution, no positive electrode tab is provided on the positive electrode winding start segment, and after the positive electrode sheet is wound to form the electrode assembly, the positive electrode winding start segment does not have a tab that directly draws current from the positive electrode winding start segment. This corresponds to an increase in the internal resistance corresponding to the positive electrode winding start segment. During charging, the charge polarization in the part of the positive electrode sheet with high internal resistance is greater than in the part of the positive electrode sheet with low internal resistance. Therefore, at full charge, the part of the positive electrode sheet with low internal resistance reaches an upper limit voltage, and the positive electrode winding start segment without a positive electrode tab does not actually reach the upper limit voltage. This corresponds to a lower voltage at the positive electrode winding start segment compared to the part of the positive electrode sheet with low internal resistance. By increasing the difficulty of ions detaching from the positive electrode winding start segment, the number of ions detaching from the positive electrode winding start segment is reduced, reducing the possibility of lithium deposition in the electrode assembly.

[0008] In some embodiments according to the first aspect of the present application, the length of the positive electrode winding start segment occupies 5% to 30% of the total length of the positive electrode sheet.

[0009] In the above technical solution, the length of the positive electrode winding start segment accounts for 5% to 30% of the total length of the positive electrode sheet. If the length of the positive electrode winding start segment is less than 5% of the total length, the increase in internal resistance of the positive electrode winding start segment is insignificant, the voltage corresponding to the positive electrode winding start segment cannot be significantly reduced, and the problem of lithium deposition at the bends of the electrode assembly cannot be significantly improved. If the length of the positive electrode winding start segment exceeds 30% of the total length of the positive electrode sheet, the temperature rise of the first positive electrode tab along the winding direction of the positive electrode sheet will be too large, leading to other risks such as thermal runaway.

[0010] In some embodiments according to the first aspect of the present application, the length of the positive electrode winding start segment occupies 10% to 25% of the total length of the positive electrode sheet.

[0011] In the above technical solution, by making the length of the positive electrode winding start segment account for 10% to 25% of the total length of the positive electrode sheet, not only can the problem of lithium precipitation occurring in the electrode assembly be significantly improved, but also the risk that the temperature rise of the first positive electrode tab along the winding direction of the positive electrode sheet becomes too large can be reduced.

[0012] In some embodiments according to the first aspect of the present application, the length of the positive electrode winding start segment accounts for 15% to 20% of the total length of the positive electrode sheet.

[0013] In the above technical solution, by making the length of the positive electrode winding start segment account for 15% to 20% of the total length of the positive electrode sheet, not only can the problem of lithium precipitation occurring in the electrode assembly be significantly improved, but also the risk that the temperature rise of the first positive electrode tab along the winding direction of the positive electrode sheet becomes too large can be reduced.

[0014] In some embodiments according to the first aspect of the present application, a plurality of positive electrode tabs are provided on the positive electrode winding extending segment. From the start end of the positive electrode winding to the end of the positive electrode winding, the area of the first positive electrode tab of the positive electrode winding extending segment is larger than the areas of the remaining positive electrode tabs of the positive electrode winding extending segment.

[0015] In the above technical solution, from the start end of the positive electrode winding to the end of the positive electrode winding, the first positive electrode tab of the positive electrode winding extending segment is subject to the temperature rise caused by the positive electrode winding start segment. By making the area of the first positive electrode tab of the positive electrode winding extending segment larger than the areas of the remaining positive electrode tabs of the positive electrode winding extending segment, the temperature rise of the positive electrode winding start segment can be effectively reduced, and the consistency of the temperature rise between the positive electrode winding start segment and the positive electrode winding extending segment can be ensured as much as possible.

[0016] In some embodiments according to the first aspect of the present application, from the start end of the positive electrode winding to the end of the positive electrode winding, the areas of the plurality of positive electrode tabs gradually become smaller.

[0017] In the above technical solution, from the positive electrode winding start end to the positive electrode winding end, the areas of the plurality of positive electrode tabs gradually decrease in the width direction of the positive electrode tabs without completely overlapping, so that each positive electrode tab has an exposed area, thereby improving the heat dissipation ability of the positive electrode tabs.

[0018] In some embodiments according to the first aspect of the present application, the wound electrode assembly further includes a negative electrode sheet, and the area of the positive electrode tab is larger than the area of the negative electrode tab of the negative electrode sheet.

[0019] In the above technical solution, no positive electrode tab is provided in the positive electrode winding start segment. Since the temperature rise of the positive electrode sheet is greater than the temperature rise of the negative electrode sheet and the heat dissipation ability of the positive electrode sheet is smaller than the heat dissipation ability of the negative electrode sheet, increasing the area of the positive electrode tab of the positive electrode sheet to be larger than the area of the negative electrode tab of the negative electrode sheet can effectively reduce the temperature rise of the positive electrode sheet and effectively improve the heat dissipation ability of the positive electrode sheet.

[0020] In some embodiments according to the first aspect of the present application, the positive electrode winding extending segment includes a positive electrode winding middle segment and a positive electrode winding end segment. The positive electrode winding middle segment is connected between the positive electrode winding start segment and the positive electrode winding end segment. The positive electrode winding middle segment is wound at least one turn, and one positive electrode tab is provided on the positive electrode winding middle segment for each layer wound one by one.

[0021] In the above technical solution, providing one positive electrode tab on the positive electrode winding middle segment for each layer wound one by one can increase the difference in internal resistance between the positive electrode winding start segment and the positive electrode winding middle segment. Thereby, the voltage difference between the positive electrode winding start segment and the positive electrode winding middle segment can be increased. Furthermore, the difficulty for ions to depart from the positive electrode winding start segment increases, and furthermore, the risk of lithium precipitation occurring at the bending portion of the positive electrode winding start segment can be reduced.

[0022] In some embodiments according to the first aspect of the present application, the positive electrode winding extending segment includes a positive electrode winding intermediate segment and a positive electrode winding end segment. The positive electrode winding intermediate segment is connected between the positive electrode winding start segment and the positive electrode winding end segment. The positive electrode winding end segment is wound at least one turn, and one positive electrode tab is provided on the positive electrode winding end segment one turn at a time, or the positive electrode tab is not provided on the positive electrode winding end segment.

[0023] In the above technical solution, since the restraining force of the negative electrode winding end segment and the positive electrode winding end segment is small, after the electrode assembly repeatedly expands and contracts, the distance between the negative electrode winding end segment and the positive electrode winding end segment becomes larger than the distance in other winding layers, and the ions in the positive electrode winding end segment cannot reach the negative electrode winding end segment, making lithium precipitation more likely. By providing one positive electrode tab on the positive electrode winding end segment one turn at a time, or not providing a positive electrode tab on the positive electrode winding end segment, the difficulty of ion detachment from the positive electrode winding end segment can be increased, thereby reducing the number of ions detaching from the positive electrode winding end segment and reducing the risk of lithium precipitation occurring in the electrode assembly.

[0024] In some embodiments according to the first aspect of the present application, the wound electrode assembly further includes a negative electrode sheet, and the number of positive electrode tabs of the positive electrode sheet is less than the number of negative electrode tabs of the negative electrode sheet.

[0025] In the above technical solution, if the total number of negative electrode tabs is more than the total number of positive electrode tabs, the internal resistance of the negative electrode sheet becomes smaller than the internal resistance of the positive electrode sheet, ensuring that the ion acceptance ability of the negative electrode sheet is superior to the ion escape ability of the positive electrode, and the problem of lithium precipitation can be more effectively improved.

[0026] In some embodiments according to the first aspect of the present application, the positive electrode winding extension segment includes a positive electrode winding intermediate segment and a positive electrode winding end segment. The wound electrode assembly further includes a negative electrode sheet. The negative electrode sheet includes a negative electrode winding start segment provided corresponding to the positive electrode winding start segment, a negative electrode winding intermediate segment provided corresponding to the positive electrode winding intermediate segment, and a negative electrode winding end segment provided corresponding to the positive electrode winding end segment. The negative electrode winding start segment is wound at least one turn, and one negative electrode tab is provided on the negative electrode winding start segment for each layer of one turn, and / or the negative electrode winding intermediate segment is wound multiple turns, and one negative electrode tab is provided on the negative electrode winding intermediate segment for each turn, and / or the negative electrode winding end segment is wound at least one turn, and one negative electrode tab is provided on the negative electrode winding end segment for each turn.

[0027] In the above technical solution, when the innermost positive electrode sheet is surrounded by the outer periphery of the innermost negative electrode sheet, the length along the winding direction of the innermost positive electrode sheet becomes larger than the length along the winding direction of the innermost negative electrode sheet. Then, the number of ions that can be detached from the innermost positive electrode sheet is larger than the number of ions that can be received by the innermost negative electrode sheet, and lithium precipitation is likely to occur. When one negative electrode tab is provided for each layer wound around once in the negative electrode winding start segment, the internal resistance of the negative electrode winding end segment becomes smaller, the ion reception ability of the negative electrode winding start segment is improved, and the risk of lithium precipitation occurring in the electrode assembly can be reduced. When one negative electrode tab is provided for each negative electrode winding intermediate segment wound around once, the ion reception ability of the negative electrode winding intermediate segment can be improved, and the risk of lithium precipitation occurring in the electrode assembly can be reduced. When the distance between the negative electrode winding end segment and the positive electrode winding end segment becomes larger than the distance in other winding layers and the ions in the positive electrode winding end segment cannot reach the negative electrode winding end segment, lithium precipitation is likely to occur. When one negative electrode tab is provided for each negative electrode winding end segment wound around once, the internal resistance of the negative electrode winding end segment becomes smaller, the ion reception ability of the negative electrode winding intermediate segment is improved, and the risk of lithium precipitation occurring in the electrode assembly can be reduced.

[0028] In some embodiments according to the first aspect of the present application, the positive electrode winding start segment has a heat dissipation structure.

[0029] In the above technical solution, since no positive electrode tab is provided in the positive electrode winding start segment, when the internal resistance of the positive electrode winding start segment becomes larger than the internal resistance when a positive electrode tab is provided in the positive electrode winding start segment, the temperature rise of the positive electrode winding start segment becomes larger. However, since the positive electrode winding start segment has a heat dissipation structure, the heat dissipation ability of the positive electrode winding start segment can be improved.

[0030] According to a second aspect, an embodiment of the present application provides a battery cell including a housing having an accommodation chamber and a wound electrode assembly provided in the accommodation chamber according to the embodiment of the first aspect.

[0031] In the above technical solution, if a positive tab is not provided on the positive winding start segment of the positive electrode sheet of the electrode assembly, it is equivalent to increasing the internal resistance corresponding to the positive winding start segment, and by increasing the difficulty of ion detachment from the positive winding start segment, the number of ions detaching from the positive winding start segment is reduced, and the possibility of lithium precipitation occurring in the electrode assembly is reduced.

[0032] According to a third aspect, an embodiment of the present application provides a battery including a case and the battery cell provided in the embodiment of the second aspect. The battery cell is accommodated in the case.

[0033] In the above technical solution, since no positive tab is provided on the positive winding start segment, this is equivalent to increasing the internal resistance corresponding to the positive winding start segment. Therefore, the possibility of lithium precipitation occurring in the electrode assembly is small, and the safety performance of the battery can be made higher.

[0034] According to a fourth aspect, an embodiment of the present application provides a power receiving device including the battery cell provided in some embodiments of the second aspect.

[0035] In the above technical solution, the possibility of lithium precipitation occurring inside the battery cell is small, and the safety of the battery cell is high, thereby improving the power receiving safety of the power receiving device.

[0036] According to a fifth aspect, an embodiment of the present application provides a method for manufacturing a wound electrode assembly, providing a positive electrode sheet including a positive winding start segment without a connected positive tab and a positive winding extending segment with a positive tab provided thereon, winding the positive electrode sheet and winding at least one turn of the positive winding start segment.

[0037] In the above technical solution, no positive electrode tab is provided in the positive electrode winding start segment, which corresponds to increasing the internal resistance corresponding to the positive electrode winding start segment after the positive electrode sheet is wound to form the electrode assembly. By increasing the difficulty of ion detachment from the positive electrode winding start segment in this way, the number of ions detaching from the positive electrode winding start segment is reduced, and the possibility of lithium precipitation occurring in the electrode assembly is reduced.

[0038] According to the sixth aspect, an embodiment of the present application provides manufacturing equipment for a wound electrode assembly including a providing device and an assembling device. The providing device is arranged to provide a positive electrode sheet including a positive electrode winding start segment without a provided connected positive electrode tab and a positive electrode winding extending segment with a provided positive electrode tab, and the assembling device is arranged to wind the positive electrode sheet and wind at least one turn of the positive electrode winding start segment.

[0039] In the above technical solution, no positive electrode tab is provided in the positive electrode winding start segment, which corresponds to increasing the internal resistance corresponding to the positive electrode winding start segment after the positive electrode sheet is wound to form the electrode assembly. By increasing the difficulty of ion detachment from the positive electrode winding start segment in this way, the number of ions detaching from the positive electrode winding start segment is reduced, and the possibility of lithium precipitation occurring in the electrode assembly is reduced.

Brief Description of the Drawings

[0040] To more clearly explain the technical solution in the embodiment of the present application, the attached drawings necessary for use in the embodiment are briefly described below. Since the following drawings only show some embodiments of the present application, they should not be regarded as limiting the scope. It is assumed that for those skilled in the art, without making progressive efforts, other related drawings can be obtained based on these drawings.

[0041]

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Embodiments for Carrying out the Invention

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, hereinafter, in combination with the drawings in the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. It is obvious that the described embodiments are not all embodiments of the present application, but some embodiments. Usually, the assemblies of the embodiments of the present application described and illustrated in the drawings here can be laid out and designed in different arrangements.

[0043] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claims of the present application, but only to show the embodiments selected in the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making inventive efforts belong to the scope of the claims of the present application.

[0044] It should be noted that, unless there is a contradiction, the embodiments in the present application and the constituent elements in the embodiments may be combined with each other.

[0045] Similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it is not necessary to further define or explain it in subsequent drawings.

[0046] In the description of the embodiments of the present application, the following must be explained. Directions and positional relationships are those based on the illustration, or the directions and positional relationships in which the product related to the application is normally placed when used, or the directions and positional relationships generally understood by those skilled in the art. They are merely for the convenience of explaining the present application and simplifying the description, and do not explicitly or implicitly indicate that the indicated devices or elements must have a specific orientation, be configured, and operated in a specific orientation. Therefore, such directions and positional relationships should not be understood as limiting the present application. Furthermore, terms such as "first", "second", "third", etc. are used only for distinguishing the description and should not be understood as indicating relative importance explicitly or implicitly.

[0047] The "plurality" mentioned in the present application refers to two or more (including two).

[0048] In the present application, the battery cell may include, but is not limited to, lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, magnesium-ion batteries, etc. The battery cell can have a cylindrical shape, a flat shape, a cuboid shape, or other shapes, and the embodiments of the present application are not limited thereto. The battery cell can generally be classified into three types: cylindrical battery cells, prismatic battery cells, and soft-pack battery cells in a packaging manner, but the embodiments of the present application are not limited thereto.

[0049] The battery referred to in the embodiments of the present application refers to a single physical module including one or more battery cells to provide a higher voltage and capacity. For example, the battery referred to in the present application can include battery modules, battery packs, etc. The battery generally includes a case for packaging one or more battery cells. The case can prevent liquids and other foreign substances from affecting the charging and discharging of the battery cells.

[0050] The battery cell includes an electrode assembly composed of a positive electrode sheet, a negative electrode sheet, and a separator, and an electrolyte. The battery cell operates mainly depending on the movement of metal ions between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer coated on the surface of the positive electrode current collector. The positive electrode current collector without the positive electrode active material layer coated thereon protrudes from the positive electrode current collector with the positive electrode active material layer coated thereon, and the positive electrode current collector without the positive electrode active material layer coated thereon is used as the positive electrode tab. Taking a lithium-ion battery as an example, the material of the positive electrode current collector may be aluminum, and the positive electrode active material may be lithium cobaltate, lithium iron phosphate, ternary lithium, or lithium manganate, etc. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on the surface of the negative electrode current collector. The negative electrode current collector without the negative electrode active material layer coated thereon protrudes from the negative electrode current collector with the negative electrode active material layer coated thereon, and the negative electrode current collector without the negative electrode active material layer coated thereon is used as the negative electrode tab. The material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon, silicon, etc. In order to ensure that it does not fuse even when a large current flows, the number of positive electrode tabs is stacked in plurality, and the number of negative electrode tabs is stacked in plurality. The material of the separator may be PP (polypropylene) or PE (polyethylene), etc. In the embodiment of the present application, the electrode assembly has a wound structure.

[0051] The development of battery technology needs to consider performance parameters of multiple aspects of design factors, such as energy density, cycle life, discharge capacity, charge and discharge rate, etc., and further, the safety of the battery needs to be considered. Lithium precipitation is one of the main factors affecting the electrical performance and safety performance of the battery. Once lithium precipitation occurs, not only will the electrical performance of the battery decrease, but dendrites are likely to be formed as the amount of lithium precipitation accumulates, and the dendrites may break through the separator and cause a short circuit in the battery, posing a safety concern. There are many causes of lithium precipitation.

[0052] On the one hand, in a wound electrode assembly, at the bent portion, along the winding direction, if the length of the positive electrode active material located on the winding center side of the positive electrode sheet is greater than the length of the negative electrode active material located on the side farther from the winding center of the negative electrode sheet located inside thereof, the number of ions that can be detached from the positive electrode sheet becomes larger than the number of ions that the negative electrode sheet can accept, making it easier to cause lithium precipitation. On the other hand, due to problems in the manufacturing process of the wound electrode assembly, the inventor has discovered that at the bent portion of the wound electrode assembly, the gap between the positive electrode sheet and the negative electrode sheet on the inner circumference is large, and lithium precipitation is likely to occur. In contrast, the magnitude of the internal resistance of the positive electrode sheet has an important influence on the ion detachment ability from the positive electrode sheet. The greater the internal resistance of the positive electrode sheet, the weaker the ion detachment ability from the positive electrode sheet, the higher the difficulty of ion detachment from the positive electrode sheet, and the lower the risk of lithium precipitation occurring. Conversely, the smaller the internal resistance of the positive electrode sheet, the stronger the ion detachment ability from the positive electrode sheet, the lower the difficulty of ion detachment from the positive electrode sheet, and the higher the risk of lithium precipitation occurring. The magnitude of the internal resistance of the negative electrode sheet has an important influence on the ion acceptance ability of the negative electrode sheet. The greater the internal resistance of the negative electrode sheet, the weaker the ion acceptance ability of the negative electrode sheet, and the higher the risk of lithium precipitation occurring. Conversely, the smaller the internal resistance of the negative electrode sheet, the stronger the ion acceptance ability of the negative electrode sheet, and the lower the risk of lithium precipitation occurring.

[0053] In view of the above, the embodiment of the present application provides a technical solution of increasing the internal resistance of the positive electrode winding start segment and increasing the difficulty of ion detachment from the positive electrode winding start segment by not providing a positive electrode tab at the positive electrode winding start segment of the positive electrode sheet, thereby reducing the number of ions detaching from the positive electrode winding start segment and reducing the possibility of lithium precipitation occurring in the electrode assembly.

[0054] The technical solution described in the embodiment of the present application is applicable to batteries and power receiving devices using the batteries.

[0055] The power receiving device may be a vehicle, a mobile phone, a portable device, a notebook computer, a steamship, a spacecraft, an electric toy, an electric tool, etc. The vehicle may be a fuel vehicle, a gas vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, a range extender vehicle, etc. The spacecraft includes airplanes, rockets, space shuttles, spaceships, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric vehicle toys, electric steamship toys, and electric airplane toys. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric drivers, electric hammers, impact drills, concrete vibrators, and electric cutters. The embodiments of the present application do not particularly limit the above power receiving device.

[0056] In the following embodiments, for the sake of convenience of description, the case where the power receiving device is a vehicle will be described as an example.

[0057] Referring to FIG. 1, FIG. 1 is a schematic configuration diagram of a vehicle 1000 provided in some embodiments of the present application. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head, or tail of the vehicle 1000. The battery 100 can be used for power supply of the vehicle 1000. For example, the battery 100 can be used as the operating power supply of the vehicle 1000.

[0058] The vehicle 1000 may further include a controller 200 and a motor 300, and is used to control the battery 100 so that the controller 200 supplies power to the motor 300. For example, it is used for the starting, navigation, and operating power applications during driving of the vehicle 1000.

[0059] In some embodiments of the present application, the battery 100 can not only be used as the operating power supply of the vehicle 1000, but also be used as the driving power supply of the vehicle 1000 to provide driving power for the vehicle 1000 by replacing or partially replacing fuel or natural gas.

[0060] Referring to FIG. 2, FIG. 2 is a schematic configuration diagram of a battery 100 provided in some embodiments of the present application. The battery 100 includes a case 10 and battery cells 20 housed within the case 10.

[0061] The case 10 is used to provide an accommodation space 11 for the battery cells 20. In some embodiments, the case 10 can include a first part 12 and a second part 13, and the first part 12 and the second part 13 define an accommodation space 11 for housing the battery cells 20 by engaging with each other. Of course, the connection location between the first part 12 and the second part 13 can be sealed by a seal (not shown), and the seal can be a sealing ring, a sealant, etc.

[0062] The first part 12 and the second part 13 can have various shapes such as a cuboid, a cylinder, etc. The first part 12 may have a hollow structure with one side open, and the second part 13 may also have a hollow structure with one side open. When the open side of the second part 13 is engaged with the open side of the first part 12, a case 10 having an accommodation space 11 is formed. Of course, the first part 12 may have a hollow structure with one side open, and the second part 13 may have a plate-like structure. When the second part 13 is engaged with the open side of the first part 12, a case 10 having an accommodation space 11 is formed.

[0063] In the battery 100, the number of battery cells 20 may be one or plural. If there are plural battery cells 20, series connection, parallel connection, or series-parallel connection is possible between the plural battery cells 20. Series-parallel connection means that there are both series connection and parallel connection among the plural battery cells 20. Between the plural battery cells 20, they may be directly connected in series, in parallel, or in series-parallel. Further, the whole composed of the plural battery cells 20 is accommodated in the case 10. Of course, plural battery cells 20 may first be connected in series, in parallel, or in series-parallel to form a battery module, and plural battery modules may be further connected in series, in parallel, or in series-parallel to be integrally formed and accommodated in the case 10. The battery cell 20 may have a cylindrical shape, a flat shape, a rectangular parallelepiped shape, or other shapes. FIG. 2 exemplarily shows the case where the battery cell 20 has a rectangular parallelepiped shape.

[0064] Referring to FIG. 3, in some embodiments, the battery 100 may further include a confluence member 30. Between the plural battery cells 20, electrical connection can be realized by the confluence member 30, thereby realizing series connection, parallel connection, or series-parallel connection of the plural battery cells 20.

[0065] Referring to FIG. 4, the battery cell 20 may include a housing 21, an electrode assembly 22, and an end cap assembly 23. The housing 21 has an opening 211 and an accommodation chamber (not shown). The electrode assembly 22 is accommodated in the accommodation chamber, and the end cap assembly 23 is used to hermetically cover the opening 211.

[0066] The housing 21 may have various shapes such as a cylindrical shape or a rectangular parallelepiped shape, for example. The shape of the housing 21 can be determined according to the specific shape of the electrode assembly 22. For example, if the electrode assembly 22 has a cylindrical structure, the housing 21 can select a cylindrical structure. If the electrode assembly 22 has a rectangular parallelepiped structure, the housing 21 can select a rectangular parallelepiped structure. FIG. 4 exemplarily shows the case where the housing 21 and the electrode assembly 22 are rectangular parallelepipeds.

[0067] The material of the housing 21 may be a plurality of types such as, for example, copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the embodiments of the present application do not particularly limit this.

[0068] The end cap assembly 23 is used to tightly cover the opening 211 of the housing 21, thereby forming a sealed accommodation chamber (not shown) for accommodating the electrode assembly 22. The accommodation room is further used to accommodate an electrolyte, for example, an electrolytic solution. The end cap assembly 23 is used as a member for outputting the electrical energy of the electrode assembly 22. The electrode terminals in the end cap assembly 23 are used to be electrically connected to the electrode assembly 22. That is, the electrode terminals are electrically connected to the tabs of the electrode assembly 22. For example, the electrode terminals and the tabs are connected by an adapter (not shown) to realize the electrical connection between the electrode terminals and the tabs.

[0069] It should be noted that the opening 211 of the housing 21 may be one or two. If the opening 211 of the housing 21 is one, the end cap assembly 23 may also be one, and two electrode terminals may be provided in the end cap assembly 23. The two electrode terminals are used to be electrically connected to the positive tab 2231 and the negative tab 2244 of the electrode assembly 22 respectively. The two electrode terminals in the end cap assembly 23 are the positive electrode terminal and the negative electrode terminal respectively. When the opening 211 of the housing 21 is two, for example, the two openings 211 are provided on the opposite sides of the housing 21, and the end cap assembly 23 may also be two. The two end cap assemblies 23 are respectively engaged with the two openings 211 of the housing 21. In this case, the electrode terminal in one end cap assembly 23 is the positive electrode terminal for electrically connecting to the positive tab 2231 of the electrode assembly 22, and the electrode terminal in the other end cap assembly 23 is the negative electrode terminal for electrically connecting to the negative sheet 224 of the electrode assembly 22.

[0070] The end cap assembly 23 can include an end cap 231, a first electrode terminal 232, a second electrode terminal 233, and a pressure relief mechanism 234.

[0071] The first electrode terminal 232 is attached to the end cap 231, and the second electrode terminal 233 is attached to the end cap 231. The pressure relief mechanism 234 is provided on the end cap 231 and is located between the first electrode terminal 232 and the second electrode terminal 233, and is arranged to operate so as to leak the internal pressure of the battery cell 20 when the internal pressure or temperature of the battery cell 20 reaches a threshold value.

[0072] The end cap 231 in the end cap assembly 23 is used to hermetically cover the opening 211 of the housing 21. The end cap 231 may have various shapes such as circular, rectangular, etc. The shape of the end cap 231 is determined by the shape of the housing 21. If the housing 21 has a cylindrical structure, a circular end cap 231 can be selected, and if the housing 21 has a cuboid structure, a rectangular end cap 231 can be selected.

[0073] The embodiments of the present application will describe the related structures using a cuboid wound electrode assembly 22.

[0074] As shown in FIG. 5, the electrode assembly 22 has a straight portion 221 and two oppositely arranged bent portions 222. Along the width direction A of the electrode assembly, both ends of the straight portion 221 are respectively connected to the two bent portions 222.

[0075] In some embodiments, the electrode assembly 22 includes a positive electrode sheet 223, and includes a positive electrode winding start segment 2232 where the positive electrode tab 2231 is not provided and a positive electrode winding extending segment 2233 where the positive electrode tab 2231 is provided, which are connected by the positive electrode sheet 223. The positive electrode winding start segment 2232 is wound at least one turn.

[0076] Each segment of the positive electrode sheet 223 is equivalent to one internal resistance, and each positive electrode tab 2231 is equivalent to connecting the internal resistances of two segments of the positive electrode sheet 223 in parallel, with the internal resistance of a parallel circuit being smaller than the internal resistance of a series circuit. It can be understood that when one tab emerges from each turn of the positive electrode sheet 223, each turn of the positive electrode sheet 223 is equivalent to one internal resistance, or when one tab emerges from each layer of each turn of the positive electrode sheet 223, each layer of the positive electrode sheet 223 is equivalent to one internal resistance. The positive electrode winding start segment 2232 does not have a positive electrode tab 2231, but the positive electrode winding extension segment 2233 has a positive electrode tab 2231. After the positive electrode sheet 223 is wound to form the electrode assembly 22, the positive electrode winding start segment 2232 does not have a tab that directly draws out the current of the positive electrode winding start segment 2232. This corresponds to an increase in the internal resistance corresponding to the positive electrode winding start segment 2232, and during charging, the charging polarization in the part of the positive electrode sheet 223 with higher internal resistance is greater than that in the part of the positive electrode sheet 223 with lower internal resistance. Therefore, during full charge, the portion of the positive electrode sheet 223 with low internal resistance reaches the upper limit voltage, while the positive electrode winding start segment 2232, where no positive electrode tab 2231 is provided, does not actually reach the upper limit voltage. This corresponds to a lower voltage at the positive electrode winding start segment 2232 compared to the portion of the positive electrode sheet 223 with low internal resistance. By increasing the difficulty of ions desorbing from the positive electrode winding start segment 2232, the number of ions desorbing from the positive electrode winding start segment 2232 is reduced, reducing the possibility of lithium deposition in the electrode assembly 22. In other words, increasing the internal resistance of at least the innermost positive electrode sheet 223 improves the ion desorption ability of the innermost positive electrode sheet 223, reducing the risk of lithium deposition in the folded portion 222, thereby reducing the risk of lithium deposition in the electrode assembly 22.

[0077] The positive electrode sheet 223 is as the "starting end of the positive electrode winding"It has a positive electrode starting end 2234 and a positive electrode winding end 2235. The positive electrode starting end 2234 is the starting position where the positive electrode sheet 223 is wound and is located in the positive electrode winding start segment 2232. The positive electrode winding end 2235 is the ending position where the positive electrode sheet 223 is wound and is located in the positive electrode winding extending segment 2233. After the winding of the positive electrode sheet 223 is completed, the positive electrode winding start segment 2232 is closer to the winding central axis than the positive electrode winding extending segment 2233. The positive electrode winding start segment 2232 further has a first connection end, and the positive electrode winding extending segment 2233 further has a second connection end. By connecting the positive electrode winding start segment 2232 to the second connection end of the positive electrode winding extending segment 2233 through the first connection end, a first connection position 2236 on the positive electrode sheet 223 is formed.

[0078] The positive electrode winding start segment 2232 is a part extending from the positive electrode starting end 2234 in the winding direction B and can extend the longest to the first positive electrode tab 2231 of the positive electrode sheet 223. Along the winding direction B, all of the first positive electrode tab 2231 of the positive electrode sheet 223 is located in the positive electrode winding extending segment 2233. Along the winding direction B, the first positive electrode tab 2231 of the positive electrode sheet 223 refers to the first positive electrode tab 2231 that meets along the winding direction B. For the convenience of description and for the purpose of illustration, the first positive electrode tab 2231 where the positive electrode sheet 223 meets along the winding direction B is defined as the first positive electrode tab 2231a.

[0079] Continuing to refer to FIG. 5, in some embodiments, the positive electrode winding extending segment 2233 includes a positive electrode winding intermediate segment 22331 and a positive electrode winding end segment 22332. The positive electrode winding intermediate segment 22331 is connected between the positive electrode winding start segment 2232 and the positive electrode winding end segment 22332, is wound at least one turn, and one positive electrode tab 2231 is provided on the positive electrode winding intermediate segment 22331 for each layer wound one turn at a time. The first positive electrode tab 2231a is located on the positive electrode winding intermediate segment 22331. When one positive electrode tab 2231 is provided on the positive electrode winding intermediate segment 22331 for each layer wound one turn at a time, and one positive electrode tab 2231 is provided on the positive electrode winding intermediate segment 22331 for each layer wound one turn at a time, the difference in internal resistance between the positive electrode winding start segment 2232 and the positive electrode winding intermediate segment 22331 can be increased, the voltage difference between the positive electrode winding start segment 2232 and the positive electrode winding intermediate segment 22331 can be increased, furthermore, the difficulty of ions departing from the positive electrode winding start segment 2232 is increased, and furthermore, the risk of lithium precipitation at the bending portion 222 of the positive electrode winding start segment 2232 is reduced.

[0080] The second connection end of the positive electrode winding extending segment 2233 is located on the positive electrode winding intermediate segment 22331. The positive electrode winding extending segment 2233 further includes a third connection end located on the positive electrode winding intermediate segment 22331 and a fourth connection end located on the positive electrode winding end segment 22332. The positive electrode winding intermediate segment 22331 is connected to the first connection end of the positive electrode winding start segment 2232 through the second connection end and forms the first connection position 2236 of the positive electrode sheet 223. The positive electrode winding intermediate segment 22331 is connected to the fourth connection end of the positive electrode winding end segment through the third connection end and forms the second connection position 2237 of the positive electrode sheet 223. electrode When connected to the fourth connection end of the winding end segment, it forms the second connection position 2237 of the positive electrode sheet 223.

[0081] The term "one round of the positive electrode sheet 223" means rotating 360° around the winding axis along the winding direction B starting from the positive electrode start end 2234. One round includes two layers, and the two layers can be divided with the thickness center plane P as the boundary. The thickness center plane P divides any one round of the positive electrode sheet 223 into two layers located on both sides thereof. The winding axis of the electrode assembly 22 is parallel to the thickness center plane P, and the thickness direction C of the electrode assembly is perpendicular to the thickness center plane P. One positive electrode tab 2231 is provided for each layer of one round in the positive electrode winding intermediate segment 22331. When the positive electrode winding intermediate segment 22331 is wound to form a plurality of complete windings, the number of positive electrode tabs 2231 in the positive electrode winding intermediate segment 22331 is an even number. When the positive electrode winding intermediate segment 22331 is wound to form one incomplete winding, the number of positive electrode tabs 2231 in the positive electrode winding intermediate segment 22331 may be an odd number. For the convenience of illustration, other positive electrode tabs 2231 other than the first positive electrode tab 2231a in the positive electrode winding intermediate segment 22331 are defined as the second positive electrode tabs 2231b.

[0082] In some embodiments, as shown in FIG. 6, one positive electrode tab 2231 may be provided for each round in the positive electrode winding intermediate segment 22331, and the tab is the first positive electrode tab 2231a.

[0083] Since the restraining force of the negative electrode winding end segment 2243 and the positive electrode winding end segment 22332 is small, after the electrode assembly expands and contracts repeatedly, the distance between the positive electrode winding end segment 22332 and the corresponding negative electrode winding end segment 2243 becomes larger than the distance in other winding layers, and the ions of the positive electrode winding end segment 22332 cannot reach the negative electrode winding end segment 2243, and lithium precipitation is likely to occur.

[0084] Based on this, referring to FIG. 6, in some embodiments, the positive electrode winding extending segment 2233 includes a positive electrode winding intermediate segment 22331 and a positive electrode winding end segment 22332. The positive electrode winding intermediate segment 22331 is connected between the positive electrode winding start segment 2232 and the positive electrode winding end segment 22332. The positive electrode winding end segment 22332 is wound at least one turn, and by providing one positive electrode tab 2231 (the third positive electrode tab 2231c in FIG. 6) on the positive electrode winding end segment 22332 for each turn, the internal resistance of the positive electrode winding end segment 22332 can be reduced, and the difficulty for ions to depart from the positive electrode winding end segment 22332 can be increased, thereby reducing the number of ions departing from the positive electrode winding end segment 22332 and reducing the risk of lithium precipitation occurring in the electrode assembly 22. For the convenience of illustration, the positive electrode tab 2231 of the positive electrode winding intermediate segment 22331 is defined as the second positive electrode tab 2231b, and the positive electrode tab 2231 of the positive electrode winding end segment 22332 is defined as the third positive electrode tab 2231c.

[0085] Of course, as shown in FIG. 7, in some embodiments, no positive electrode tab 2231 is provided on the positive electrode winding end segment 22332. By being able to increase the internal resistance of the positive electrode winding end segment 22332, the difficulty for ions to depart from the positive electrode winding end segment 22332 is increased, and the possibility of lithium precipitation occurring in the electrode assembly 22 is reduced.

[0086] Based on this, as shown in FIG. 8, in some embodiments, the positive electrode winding extending segment 2233 includes a positive electrode winding intermediate segment 22331 and a positive electrode winding end segment 22332, and the wound electrode assembly 22 further includes a negative electrode sheet 224. The negative electrode sheet 224 includes a negative electrode winding start segment 2241 provided corresponding to the positive electrode winding start segment 2232, a negative electrode winding intermediate segment 2242 provided corresponding to the positive electrode winding intermediate segment 22331, and a negative electrode winding end segment 2243 provided corresponding to the positive electrode winding end segment 22332. The negative electrode winding start segment 2241 is wound at least one turn, and one negative electrode tab 2244 is provided on the negative electrode winding start segment 2241 for each layer wound one turn at a time. By providing one negative electrode tab 2244 for each layer wound one turn at a time on the negative electrode winding start segment 2241, the start internal resistance of the segment 224 1 can be reduced, the ion acceptance ability of the negative electrode winding start segment 2241 can be improved, and the risk of lithium precipitation occurring in the electrode assembly 22 can be reduced. In other words, the internal resistance of at least the innermost negative electrode sheet 224 can be reduced, the ion acceptance ability of the innermost negative electrode sheet 224 can be improved, and the risk of lithium precipitation occurring in the electrode assembly 22 can be reduced. For the convenience of illustration, the negative electrode tab 2244 of the negative electrode winding start segment 2241 is defined as the first negative electrode tab 2244a, the negative electrode tab 2244 of the negative electrode winding intermediate segment 2242 is defined as the second negative electrode tab 2244b, and the negative electrode tab 2244 of the negative electrode winding end segment 2243 is defined as the third negative electrode tab 2244c.

[0087] The fact that the positive electrode winding start segment 2232 is provided corresponding to the negative electrode winding start segment 2241 means that the positive electrode winding start segment 2232 corresponds to the inner negative electrode sheet 224, and the fact that the positive electrode winding end segment 22332 is provided corresponding to the negative electrode winding end segment 2243 means that the negative electrode winding end segment 2243 corresponds to the inner positive electrode sheet 223.

[0088] The negative electrode sheet 224 has a negative electrode start end 2245 and a negative electrode winding end 2246. The negative electrode start end 2245 is the starting position where the negative electrode sheet 224 is wound, and is located at the negative electrode winding start segment 2241. The negative electrode winding end 2246 is the ending position where the negative electrode sheet 224 is wound, and is located at the negative electrode winding end segment 2243. After the winding of the negative electrode is completed, the negative electrode winding start segment 2241 is closer to the winding central axis than the negative electrode winding intermediate segment 2242 and the negative electrode winding end segment 2243. The negative electrode winding start segment further has a fifth connection end. The negative electrode winding end segment 2243 further has a sixth connection end. The negative electrode winding intermediate segment 2242 further has a seventh connection end and an eighth connection end. The negative electrode winding start segment is connected to the seventh connection end of the negative electrode winding intermediate segment 2242 through the fifth connection end, thereby forming a third connection position 2247 of the negative electrode sheet 224. The negative electrode winding end segment is connected to the eighth connection end of the negative electrode winding intermediate segment 2242 through the sixth connection end, thereby forming a fourth connection position 2248 of the negative electrode sheet 224.

[0089] As shown in FIG. 9, in some embodiments, one negative electrode tab 2244 is provided on the negative electrode winding start segment 2241 for each turn. In other embodiments, the negative electrode tabs 2244 on the negative electrode winding start segment 2241 may adopt other arrangement forms.

[0090] Since no positive electrode tab 2231 is provided on the positive electrode winding start segment 2232, along the winding direction B, the first tab that exits the electrode assembly 22 is the first negative electrode tab 2244 located on the negative electrode winding start segment 2241.

[0091] Continuing to refer to FIG. 9, in some embodiments, the negative electrode winding intermediate segment 2242 is wound multiple times, and one negative electrode tab 2244 (the second negative electrode tab 2244b in FIG. 9) is provided for each turn of the negative electrode winding intermediate segment 2242, which can improve the ion acceptance ability of the negative electrode winding intermediate segment 2242 and reduce the risk of lithium precipitation in the electrode assembly 22. In some other embodiments, one negative electrode tab 2244 (the second negative electrode tab 2244b in FIG. 9) may be provided for each layer wound one by one of the negative electrode winding intermediate segment 2242.

[0092] Continuing to refer to FIG. 9, in some embodiments, the negative electrode winding end segment 2243 is wound at least once, and one negative electrode tab 2244 (the third negative electrode tab 2244c in FIG. 9) is provided for each turn of the negative electrode winding end segment 2243, which can improve the ion acceptance ability of the negative electrode winding start segment 2241 and reduce the risk of lithium precipitation in the electrode assembly 22. In some other embodiments, one negative electrode tab 2244 may be provided for each layer wound one by one of the negative electrode winding end segment 2243.

[0093] As shown in FIG. 10, in some embodiments, the negative electrode winding start segment 2241 is wound at least one turn, and one negative electrode tab 2244 (the first negative electrode tab 2244a in FIG. 10) is provided on the negative electrode winding start segment 2241 for each layer wound one by one. The negative electrode winding intermediate segment 2242 is wound at least one turn, and one negative electrode tab 2244 (the second negative electrode tab 2244b in FIG. 10) is provided on the negative electrode winding intermediate segment 2242 for each turn. The negative electrode winding end segment 2243 is wound at least one turn, and one negative electrode tab 2244 (the third negative electrode tab 2244c in FIG. 10) is provided on the negative electrode winding end segment 2243 for each layer wound one by one. The distance between the negative electrode winding end segment 2243 and the positive electrode winding end segment 22332 becomes larger than the distances in other winding layers, and the ions of the positive electrode winding end segment 22332 cannot reach the negative electrode winding end segment 2243, making lithium prone to precipitation. By providing one negative electrode tab 2244 on the negative electrode winding end segment 2243 for each layer wound one by one, the internal resistance of the negative electrode winding end segment 2243 is small, and the ion acceptance ability of the negative electrode winding segment can be improved, and the risk of lithium precipitation occurring in the electrode assembly 22 can be reduced. No positive electrode tab 2231 is provided on the positive electrode winding start segment 2232, one positive electrode tab (the first positive electrode tab 2231a and the second positive electrode tab 2231b in FIG. 10) is provided for each layer wound one by one of the positive electrode winding intermediate segment, and no positive electrode tab 2231 is provided on the positive electrode winding end segment 22332. end segment 2243 can be improved, and the risk of lithium precipitation occurring in the electrode assembly 22 can be reduced. No positive electrode tab 2231 is provided on the positive electrode winding start segment 2232, one positive electrode tab (the first positive electrode tab 2231a and the second positive electrode tab 2231b in FIG. 10) is provided for each layer wound one by one of the positive electrode winding intermediate segment, and no positive electrode tab 2231 is provided on the positive electrode winding end segment 22332.

[0094] In some embodiments, the electrode assembly 22 further includes a separator 225, and the separator 225 is used to separate the positive electrode sheet 223 and the negative electrode sheet 224 so as to avoid a short circuit caused by the direct contact of the positive electrode sheet 223 and the negative electrode sheet 224.

[0095] In some embodiments, the length of the positive electrode winding start segment 2232 occupies 5% to 30% of the total length of the positive electrode sheet 223. When the length of the positive electrode winding start segment 2232 is less than 5% of the total length, the increase in the internal resistance of the positive electrode winding start segment 2232 is not obvious, the voltage corresponding to the positive electrode winding start segment 2232 cannot be significantly reduced, and the problem of lithium precipitation at the bending portion 222 of the electrode assembly 22 cannot be significantly improved. When the length of the positive electrode winding start segment 2232 exceeds 30% of the total length of the positive electrode sheet 223, the temperature rise of the first positive electrode tab 2231 along the winding direction B of the positive electrode sheet 223 becomes too large, causing other risks such as thermal runaway.

[0096] It should be noted that the total length of the positive electrode sheet 223 refers to the dimension of the portion between the positive electrode start end 2234 and the positive electrode winding end 2235 of the positive electrode sheet 223 along the winding direction B. The length of the positive electrode winding start segment 2232 refers to the dimension of the portion between the positive electrode start end 2234 and the first positive electrode tab 2231a of the positive electrode sheet 223 along the winding direction B.

[0097] In some embodiments, the length of the positive electrode winding start segment 2232 occupies 10% to 25% of the total length of the positive electrode sheet 223, which can not only significantly improve the problem of lithium precipitation in the electrode assembly 22, but also reduce the risk that the temperature rise of the first positive electrode tab 2231 along the winding direction B of the positive electrode sheet 223 becomes too large.

[0098] In some embodiments, the length of the positive electrode winding start segment 2232 occupies 15% to 20% of the total length of the positive electrode sheet 223, which can not only significantly improve the problem of lithium precipitation in the electrode assembly 22, but also reduce the risk that the temperature rise of the first positive electrode tab 2231 along the winding direction B of the positive electrode sheet 223 becomes too large. Also, the length of the positive electrode winding extending segment 2233 provided with the positive electrode tab 2231 can be made appropriate, and an appropriate number of positive electrode tabs 2231 can be provided to ensure the overcurrent area.

[0099] In some embodiments, a plurality of positive electrode tabs 2231 are provided on the positive electrode winding extending segment 2233. From the start end of the positive electrode winding to the end 2235 of the positive electrode winding, the area of the first positive electrode tab 2231 of the positive electrode winding extending segment 2233 is larger than the areas of the remaining positive electrode tabs 2231 of the positive electrode winding extending segment 2233. In other words, along the winding direction B, the area of the first positive electrode tab 2231a is larger than the areas of the other positive electrode tabs 2231 other than the first positive electrode tab 2231a among the plurality of positive electrode tabs 2231. Along the winding direction B, the first positive electrode tab of the positive electrode winding extending segment 2233 is subject to the temperature rise caused by the positive electrode winding start segment 2232. By making the area of the first positive electrode tab 2231 of the positive electrode winding extending segment 2233 larger than the areas of the remaining positive electrode tabs 2231 of the positive electrode winding extending segment 2233, the temperature rise of the positive electrode winding start segment 2232 can be effectively reduced, and the consistency of the temperature rise between the positive electrode winding start segment 2232 and the positive electrode winding extending segment 2233 can be ensured as much as possible.

[0100] The remaining positive electrode tabs 2231 refer to the other positive electrode tabs 2231 other than the first positive electrode tab 2231.

[0101] As shown in FIG. 11, in some embodiments, the width dimension of the first positive electrode tab 2231a is larger than the width dimensions of the remaining positive electrode tabs 2231, and the height dimension of the first positive electrode tab 2231a is equal to the height dimensions of the remaining positive electrode tabs 2231. Thereby, the area of the first positive electrode tab 2231a is made larger than the areas of the remaining positive electrode tabs 2231. The width dimension of the positive electrode tab 2231 is the dimension along the winding direction B of the positive electrode tab 2231, and the height dimension of the positive electrode tab 2231 is the dimension along the width direction of the positive electrode sheet 223.

[0102] As shown in FIG. 12, in some embodiments, the height dimension of the first positive electrode tab 2231a is larger than the height dimensions of the remaining positive electrode tabs 2231, and the width dimension of the first positive electrode tab 2231a is equal to the width dimensions of the remaining positive electrode tabs 2231. Thereby, the area of the first positive electrode tab 2231a is made larger than the areas of the remaining positive electrode tabs 2231.

[0103] As shown in FIG. 13, in some embodiments, the width dimension of the first positive tab 2231a is larger than the width dimensions of the remaining positive tabs 2231, and the height dimension of the first positive tab 2231a is larger than the height dimensions of the remaining positive tabs 2231, whereby the area of the first positive tab 2231a is made larger than the area of the remaining positive tabs 2231.

[0104] The areas of the remaining positive tabs 2231 may or may not be equal. In some embodiments, along the winding direction B, the areas of the remaining positive tabs 2231 gradually decrease. That is, from the positive electrode start end 2234 to the positive electrode winding end 2235 (i.e., along the winding direction B), the areas of the plurality of positive tabs 2231 gradually decrease. After such a positive electrode sheet 223 is wound, as shown in FIGS. 14 and 15, when the positive tabs 2231 are stacked and arranged, the plurality of positive tabs 2231 do not completely overlap, and by gradually decreasing the areas of the plurality of positive tabs 2231 so as to have a shift in the width direction of the positive tabs 2231, each positive tab 2231 has an exposed area, thereby improving the heat dissipation ability at the positive tabs 2231.

[0105] In some embodiments, the wound electrode assembly 22 further includes a negative electrode sheet 224, and the area of the positive tab 2231 is larger than the area of the negative tab 2244 of the negative electrode sheet 224. Since the positive tab 2231 is not provided in the positive electrode winding start segment 2232, the temperature rise of the positive electrode sheet 223 is larger than the temperature rise of the negative electrode sheet 224, the heat dissipation ability of the positive electrode sheet 223 is lower than the heat dissipation ability of the negative electrode sheet 224, the area of the positive tab 2231 of the positive electrode sheet 223 is larger than the area of the negative tab 2244 of the negative electrode sheet 224, the temperature rise of the positive electrode sheet 223 can be effectively reduced, and the heat dissipation ability of the positive electrode sheet 223 can be effectively improved.

[0106] 16 , in some embodiments, a heat dissipation structure 22321 is provided on the positive electrode winding start segment 2232. Because the positive electrode winding start segment 2232 does not have a positive electrode tab 2231, the internal resistance of the positive electrode winding start segment 2232 is greater than the internal resistance when the positive electrode winding start segment 2232 has a positive electrode tab 2231, resulting in a greater temperature rise in the positive electrode winding start segment 2232. By providing the heat dissipation structure 22321 on the positive electrode winding start segment 2232, the heat dissipation capability of the positive electrode winding start segment 2232 can be improved.

[0107] The heat dissipation structure 22321 is provided in the positive electrode winding start segment 2232 and is connected to at least one side in the width direction of the current collector on which the active material layer of the positive electrode sheet 223 is applied, the heat dissipation structure 22321 is a protrusion protruding from the active material layer, the height dimension of the heat dissipation structure 22321 is smaller than the height dimension of the positive electrode tab 2231, and the heat dissipation structure 22321 is not connected to an adapter (not shown) and is electrically connected to an adapter (not shown) or an electrode terminal only via the positive electrode tab 2231 so as to draw out current without being involved in overcurrent.

[0108] In some embodiments, the negative electrode winding start segment 2241 may be provided with a heat dissipation structure 22321, and the structure of the heat dissipation structure 22321 of the negative electrode winding start segment 2241 can refer to the heat dissipation structure 22321 on the positive electrode winding start segment 2232.

[0109] In some embodiments, the wound electrode assembly 22 further includes a negative electrode sheet 224, and the number of positive electrode tabs 2231 on the positive electrode sheet 223 is smaller than the number of negative electrode tabs 2244 on the negative electrode sheet 224. When the total number of negative electrode tabs 2244 is greater than the total number of positive electrode tabs 2231, the internal resistance of the negative electrode sheet 224 is smaller than the internal resistance of the positive electrode sheet 223, ensuring that the ion acceptance capacity of the negative electrode sheet 224 is greater than the ion escape capacity of the positive electrode, thereby more effectively alleviating the problem of lithium deposition.

[0110] In the embodiments of the present application, for the convenience of illustration, with respect to the positive electrode tab 2231 and the negative electrode tab 2244, the positive electrode tab 2231 is made to extend beyond the positive electrode sheet 223 in the thickness direction C of the electrode assembly, and the negative electrode tab 2244 is made to extend beyond the negative electrode sheet 224 in the thickness direction C of the electrode assembly. However, it must be explained that the dimensions of the positive electrode tab 2231 and the negative electrode tab 2244 in the thickness direction C of the electrode assembly are not limited.

[0111] As shown in FIG. 17, the embodiments of the present application provide a method for manufacturing a wound electrode assembly 22. Step S100 of providing a positive electrode sheet 223 including a positive electrode winding start segment 2232 where the connected positive electrode tab 2231 is not provided and a positive electrode winding extending segment 2233 where the positive electrode tab 2231 is provided. Including step S200 of winding and providing the positive electrode sheet 223 and winding the positive electrode winding start segment 2232 at least one turn.

[0112] The positive electrode tab 2231 is not provided on the positive electrode winding start segment 2232. After the positive electrode sheet 223 is wound to form the electrode assembly 22, it corresponds to an increase in the internal resistance corresponding to the positive electrode winding start segment 2232. Thereby, by increasing the difficulty of ions detaching from the positive electrode winding start segment 2232, the number of ions detaching from the positive electrode winding start segment 2232 is reduced, and the possibility of lithium precipitation in the electrode assembly 22 is reduced.

[0113] As shown in FIG. 18, the embodiments of the present application provide manufacturing equipment 2000 for a wound electrode assembly. The manufacturing equipment 2000 for a wound electrode assembly includes a providing device 2100 and an assembling device 2200. The providing device 2100 is arranged to provide a positive electrode sheet 223 including a positive electrode winding start segment 2232 where the connected positive electrode tab 2231 is not provided and a positive electrode winding extending segment 2233 where the positive electrode tab 2231 is provided. The assembling device 2200 is arranged to wind the positive electrode sheet 223 and wind the positive electrode winding start segment 2232 at least one turn.

[0114] The positive electrode tab 2231 is not provided in the positive electrode winding start segment 2232. After the positive electrode sheet 223 is wound to form the electrode assembly 22, it corresponds to the increase in the internal resistance corresponding to the positive electrode winding start segment 2232. Thereby, by increasing the difficulty of ion detachment from the positive electrode winding start segment 2232, the number of ions detaching from the positive electrode winding start segment 2232 is reduced, and the possibility of lithium precipitation occurring in the electrode assembly 22 is reduced.

[0115] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various modifications and changes can be made to the present application. Any corrections, equivalent substitutions, improvements, etc. made within the scope of the spirit and principle of the present application should be included in the scope of the rights of the present application.

Explanation of Reference Numerals

[0116] 1000 - Vehicle; 100 - Battery; 10 - Case; 11 - Accommodation Space; 12 - First Part; 13 - Second Part; 20 - Battery Cell; 21 - Housing; 211 - Opening; 22 - Electrode Assembly; 221 - Straight Part; 222 - Bent Part; 223 - Positive Electrode Sheet; 2231 - Positive Electrode Tab; 2231a - First Positive Electrode Tab; 2231b - Second Positive Electrode Tab; 2231c - Third Positive Electrode Tab; 2232 - Positive Electrode Winding Start Segment; 22321 - Heat Dissipation Structure; 2233 - Positive Electrode Winding Extension Segment; 22331 - Positive Electrode Winding Middle Segment; 22332 - Positive Electrode Winding End Segment; 2234 - Positive Electrode Start End; 2235 - Positive Electrode Winding End; 2236 - First Connection Position; 2237 - Second Connection Position; 224 - Negative Electrode Sheet; 2241 - Negative Electrode Winding Start Segment; 2242 - Negative Electrode Winding Middle Segment; 2243 - Negative Electrode Winding End Segment; 2244 - Negative Electrode Tab; 2244a - First Negative Electrode Tab; 2244b - Second Negative Electrode Tab; 2244c - Third Negative Electrode Tab; 2245 - Negative Electrode Start End; 2246 - Negative Electrode Winding End; 2247 - Third Connection Position; 2248 - Fourth Connection Position; 225 - Separator; 23 - End Cap Assembly; 231 - End Cap; 232 - First Electrode Terminal; 233 - Second Electrode Terminal; 234 - Pressure Relief Mechanism; 30 - Confluence Member; 200 - Controller; 300 - Motor; 2000 - Manufacturing Equipment for Wound Electrode Assembly; 2100 - Providing Device; 2200 - Assembly Device; A - Width Direction of Electrode Assembly; B - Winding Direction; C - Thickness Direction of Electrode Assembly; P - Thickness Center Plane.

Claims

[

1. ] A wound electrode assembly having a bent portion with a wound structure, comprising: including a positive electrode sheet; the positive electrode sheet includes a positive electrode winding start segment without a connected positive electrode tab and a positive electrode winding extending segment with the positive electrode tab provided thereon; the positive electrode winding start segment is wound at least one turn; a plurality of positive electrode tabs are provided on the positive electrode winding extending segment, and from the positive electrode winding start end to the positive electrode winding end, the area of the first positive electrode tab of the positive electrode winding extending segment is larger than the area of the remaining positive electrode tabs of the positive electrode winding extending segment; the length of the positive electrode winding start segment occupies 10% to 25% of the total length of the positive electrode sheet; one positive electrode tab is provided on the positive electrode winding extending segment for each turn; a wound electrode assembly. [

2. ] A wound electrode assembly having a bent portion with a wound structure, comprising: including a positive electrode sheet; the positive electrode sheet includes a positive electrode winding start segment without a connected positive electrode tab and a positive electrode winding extending segment with the positive electrode tab provided thereon; the positive electrode winding start segment is wound at least one turn; a plurality of positive electrode tabs are provided on the positive electrode winding extending segment, and from the positive electrode winding start end to the positive electrode winding end, the area of the first positive electrode tab of the positive electrode winding extending segment is larger than the area of the remaining positive electrode tabs of the positive electrode winding extending segment; the length of the positive electrode winding start segment occupies 10% to 25% of the total length of the positive electrode sheet; the positive electrode winding extending segment includes a positive electrode winding intermediate segment and a positive electrode winding end segment, the positive electrode winding intermediate segment is connected between the positive electrode winding start segment and the positive electrode winding end segment, is wound at least one turn, one positive electrode tab is provided on the positive electrode winding intermediate segment for each layer of each turn, and no positive electrode tab is provided on the positive electrode winding end segment; a wound electrode assembly. [

3. ] A wound electrode assembly having a bent portion with a wound structure, comprising: including a positive electrode sheet; the positive electrode sheet includes a positive electrode winding start segment without a connected positive electrode tab and a positive electrode winding extending segment with the positive electrode tab provided thereon; the positive electrode winding start segment is wound at least one turn; A plurality of the positive electrode tabs are provided on the positive electrode winding extension segment, and from the positive electrode winding start end to the positive electrode winding end, the area of the first positive electrode tab of the positive electrode winding extension segment is larger than the areas of the remaining positive electrode tabs of the positive electrode winding extension segment. The length of the positive electrode winding start segment occupies 10% to 25% of the total length of the positive electrode sheet. The positive electrode winding extension segment includes a positive electrode winding intermediate segment and a positive electrode winding end segment. The positive electrode winding intermediate segment is connected between the positive electrode winding start segment and the positive electrode winding end segment, and is wound at least one turn. One positive electrode tab is provided on the positive electrode winding intermediate segment for each turn, and no positive electrode tab is provided on the positive electrode winding end segment. A wound electrode assembly.

4. From the positive electrode winding start end to the positive electrode winding end, the areas of the plurality of positive electrode tabs gradually decrease. The wound electrode assembly according to any one of claims 1 to 3.

5. Further including a negative electrode sheet, and the number of the positive electrode tabs of the positive electrode sheet is less than the number of the negative electrode tabs of the negative electrode sheet. The wound electrode assembly according to any one of claims 1 to 4.

6. The wound electrode assembly further includes a negative electrode sheet, and the negative electrode sheet includes a negative electrode winding start segment provided corresponding to the positive electrode winding start segment, a negative electrode winding intermediate segment provided corresponding to the positive electrode winding intermediate segment, and a negative electrode winding end segment provided corresponding to the positive electrode winding end segment. The negative electrode winding start segment is wound at least one turn, and one negative electrode tab is provided on the negative electrode winding start segment for each layer of each turn, and / or The negative electrode winding intermediate segment is wound at least one turn, and one negative electrode tab is provided on the negative electrode winding intermediate segment for each layer of each turn, and no negative electrode tab is provided on the negative electrode winding end segment, or The negative electrode winding intermediate segment is wound at least one turn, and one negative electrode tab is provided on the negative electrode winding intermediate segment for each turn, and no negative electrode tab is provided on the negative electrode winding end segment. The wound electrode assembly according to claim 2 or 3.

7. The positive electrode winding start segment has a heat dissipation structure. The wound electrode assembly according to any one of claims 1 to 6.

8. A housing having a housing chamber, The wound electrode assembly according to any one of claims 1 to 7, housed in the housing chamber, Battery cell.

9. A case, The battery cell according to claim 8, housed in the case, Battery.

10. A power receiving device including the battery cell according to claim 8. Power receiving device.

11. A method for manufacturing a wound electrode assembly having a bent portion with a wound structure, Providing a positive electrode sheet including a positive electrode winding start segment without a connected positive electrode tab and a positive electrode winding extending segment with the positive electrode tab provided, wherein a plurality of the positive electrode tabs are provided in the positive electrode winding extending segment, and from the positive electrode winding start end to the positive electrode winding end, the area of the first positive electrode tab in the positive electrode winding extending segment is larger than the areas of the remaining positive electrode tabs in the positive electrode winding extending segment; Winding the positive electrode sheet and winding the positive electrode winding start segment at least once; The length of the positive electrode winding start segment occupies 10% to 25% of the total length of the positive electrode sheet; One positive electrode tab is provided in the positive electrode winding extending segment one by one for each turn; Method for manufacturing a wound electrode assembly.

12. A method for manufacturing a wound electrode assembly having a bent portion with a wound structure, Providing a positive electrode sheet including a positive electrode winding start segment without a connected positive electrode tab and a positive electrode winding extending segment with the positive electrode tab provided, wherein a plurality of the positive electrode tabs are provided in the positive electrode winding extending segment, and from the positive electrode winding start end to the positive electrode winding end, the area of the first positive electrode tab in the positive electrode winding extending segment is larger than the areas of the remaining positive electrode tabs in the positive electrode winding extending segment; Winding the positive electrode sheet and winding the positive electrode winding start segment at least once; The length of the positive electrode winding start segment occupies 10% to 25% of the total length of the positive electrode sheet; The positive electrode winding extending segment includes a positive electrode winding intermediate segment and a positive electrode winding end segment, the positive electrode winding intermediate segment is connected between the positive electrode winding start segment and the positive electrode winding end segment, is wound at least once, one positive electrode tab is provided in the positive electrode winding intermediate segment for each layer for each turn, and no positive electrode tab is provided in the positive electrode winding end segment; Method for manufacturing a wound electrode assembly. A manufacturing method of a wound electrode assembly having a bent portion with a wound structure, comprising: providing a positive electrode sheet including a positive electrode winding start segment without a connected positive electrode tab and a positive electrode winding extending segment with the positive electrode tab provided thereon, wherein a plurality of the positive electrode tabs are provided on the positive electrode winding extending segment, and from a positive electrode winding start end to a positive electrode winding end, an area of the first positive electrode tab of the positive electrode winding extending segment is larger than an area of the remaining positive electrode tabs of the positive electrode winding extending segment; winding the positive electrode sheet and winding at least one turn of the positive electrode winding start segment; wherein a length of the positive electrode winding start segment occupies 10% to 25% of a total length of the positive electrode sheet; the positive electrode winding extending segment includes a positive electrode winding intermediate segment and a positive electrode winding end segment, the positive electrode winding intermediate segment is connected between the positive electrode winding start segment and the positive electrode winding end segment, is wound at least one turn, and one of the positive electrode tabs is provided on the positive electrode winding intermediate segment one by one turn, and no positive electrode tab is provided on the positive electrode winding end segment; A manufacturing method of a wound electrode assembly. A manufacturing apparatus of a wound electrode assembly having a bent portion with a wound structure, comprising: a providing device arranged to provide a positive electrode sheet including a positive electrode winding start segment without a connected positive electrode tab and a positive electrode winding extending segment with the positive electrode tab provided thereon, wherein a plurality of the positive electrode tabs are provided on the positive electrode winding extending segment, and from a positive electrode winding start end to a positive electrode winding end, an area of the first positive electrode tab of the positive electrode winding extending segment is larger than an area of the remaining positive electrode tabs of the positive electrode winding extending segment; an assembling device arranged to wind the positive electrode sheet and wind at least one turn of the positive electrode winding start segment; wherein a length of the positive electrode winding start segment occupies 10% to 25% of a total length of the positive electrode sheet; one of the positive electrode tabs is provided on the positive electrode winding extending segment one by one turn; A manufacturing apparatus of a wound electrode assembly. A manufacturing apparatus of a wound electrode assembly having a bent portion with a wound structure, comprising: A providing device that includes a positive electrode winding start segment where no connected positive electrode tab is provided and a positive electrode winding extending segment where the positive electrode tab is provided, and a plurality of the positive electrode tabs are provided in the positive electrode winding extending segment, and from the positive electrode winding start end to the positive electrode winding end, the area of the first positive electrode tab in the positive electrode winding extending segment is arranged to provide a positive electrode sheet that is larger than the areas of the remaining positive electrode tabs in the positive electrode winding extending segment. An assembling device that winds the positive electrode sheet and is arranged to wind at least one turn around the positive electrode winding start segment. The length of the positive electrode winding start segment occupies 10% to 25% of the total length of the positive electrode sheet. The positive electrode winding extending segment includes a positive electrode winding intermediate segment and a positive electrode winding end segment. The positive electrode winding intermediate segment is connected between the positive electrode winding start segment and the positive electrode winding end segment, is wound at least one turn, and one positive electrode tab is provided in the positive electrode winding intermediate segment for each layer wound one by one, and no positive electrode tab is provided in the positive electrode winding end segment. Manufacturing equipment for a wound electrode assembly.

16. Manufacturing equipment for a wound electrode assembly having a bent portion with a wound structure, A providing device that includes a positive electrode winding start segment where no connected positive electrode tab is provided and a positive electrode winding extending segment where the positive electrode tab is provided, and a plurality of the positive electrode tabs are provided in the positive electrode winding extending segment, and from the positive electrode winding start end to the positive electrode winding end, the area of the first positive electrode tab in the positive electrode winding extending segment is arranged to provide a positive electrode sheet that is larger than the areas of the remaining positive electrode tabs in the positive electrode winding extending segment. An assembling device that winds the positive electrode sheet and is arranged to wind at least one turn around the positive electrode winding start segment. The length of the positive electrode winding start segment occupies 10% to 25% of the total length of the positive electrode sheet. The positive electrode winding extending segment includes a positive electrode winding intermediate segment and a positive electrode winding end segment. The positive electrode winding intermediate segment is connected between the positive electrode winding start segment and the positive electrode winding end segment, is wound at least one turn, and one positive electrode tab is provided in the positive electrode winding intermediate segment for each turn, and no positive electrode tab is provided in the positive electrode winding end segment. Manufacturing equipment for a wound electrode assembly.

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