Electrode assembly and related preparation device, battery cell and battery

Abstract

The present application discloses an electrode assembly and a preparation device, a battery cell and a battery related thereto. The electrode assembly includes: an isolating member and two pole pieces with opposite polarities, wherein the two pole pieces and the isolating member are wound to form the electrode assembly. The isolating member is configured to have an initial winding portion, which is wound at the center of the electrode assembly, and at least a portion of the initial winding portion is configured to be fused by the isolating member. The electrode assembly of the present application is achieved by fusing at least a portion of the isolating members of the initial section into one piece when the isolating members are unwound, so as to increase the friction between the interfaces of the isolating members. In this way, when the winding needle is withdrawn, the winding needle is not likely to bring out the isolating member due to the increased friction between the isolating members and the integrated structure.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to an electrode assembly and a preparation device, a battery cell and a battery related thereto. Background Art

[0002] Energy conservation and emission reduction are the key to the sustainable development of the automobile industry. Electric vehicles have become an important part of the sustainable development of the automobile industry due to their advantages in energy conservation and environmental protection. For electric vehicles, battery technology is an important factor in their development.

[0003] In the prior art, the electrode assembly in the battery cell is usually formed by winding with a winding needle, and the electrode assembly is wound into a roll structure and then put into the shell for use. However, when the winding needle is pulled out after winding, the separator is often pulled out, resulting in poor alignment of the electrode assembly, affecting subsequent problems such as installation and production capacity. Summary of the invention

[0004] In view of the above problems, the present application provides an electrode assembly and a preparation device, a battery cell and a battery related thereto, which can alleviate the problem of poor needle extraction during the winding process of the electrode assembly.

[0005] In a first aspect, the present application provides an electrode assembly, comprising a separator and two pole pieces with opposite polarities, wherein the two pole pieces and the separator are wound to form the electrode assembly, wherein the separator is configured to have an initial winding portion wound at the center of the electrode assembly, and at least a portion of the initial winding portion is configured to be fused by the separator.

[0006] In this embodiment, after the heated separator is cooled, the separators in this part will be attached as a whole and hardened by crystallization to finally form a fusion body. Through this arrangement, on the one hand, after the fusion body is cooled, the adjacent separators form adhesion, which can effectively increase the friction between the separator interfaces, thereby reducing the risk of pulling out the separator when the winding needle is withdrawn; on the other hand, after the fusion body is cooled, the overall hardness can be increased by crystallization, thereby providing a certain support effect on the electrode assembly.

[0007] In some embodiments, the number of turns of the separator in the initial winding portion ranges from 3 to 10 turns.

[0008] In this embodiment, the number of turns of the isolation member of the initial winding portion is in the range of 3 to 10 turns, which can effectively increase the friction between the interfaces of adjacent isolation members while reducing the space occupied by the initial winding portion, thereby effectively ensuring the overall effective volume of the electrode assembly.

[0009] In some embodiments, the initial coil has a diameter ranging from 0.1 mm to 4 mm.

[0010] In this embodiment, the diameter of the initial winding portion is in the range of 0.1 mm-4 mm, which can increase the friction between the interfaces of adjacent isolation members while reducing the space occupied by the initial winding portion, thereby effectively ensuring the overall effective volume of the electrode assembly.

[0011] In some embodiments, the separator includes a first separator and a second separator; the electrode assembly is configured such that: in a winding structure after an initial winding portion, a negative electrode sheet is inserted between the first separator and the second separator, and in a subsequent winding structure, a positive electrode sheet is inserted between the first separator and the second separator.

[0012] In this embodiment, by simultaneously winding the first separator and the second separator into the initial winding portion, the winding of the separator can be facilitated, thereby further reducing the difficulty of winding the electrode assembly; at the same time, by simultaneously winding the first separator and the second separator into the initial winding portion, the hardness of the initial winding portion can be improved by using fewer turns of separators. In addition, the negative electrode sheet is first inserted into the first separator and the second separator for winding, and after winding for a certain length, the positive electrode sheet is inserted for winding, which can also effectively avoid lithium precipitation.

[0013] In a second aspect, the present application provides an electrode assembly preparation device, comprising: a winding mechanism for winding a separator and two pole pieces with opposite polarities to form an electrode assembly, wherein the separator is configured to have an initial winding portion wound at the center of the electrode assembly. The winding mechanism comprises a hot stamping device, which is used to detachably abut the winding mechanism to fuse at least part of the initial winding portion.

[0014] In this embodiment, the electrode assembly preparation device in the present application heats the separator by setting a hot blanching device, and the attached winding after heating can form adhesion after cooling to form a fusion body. In this way, on the one hand, after the fusion body is cooled, the adjacent separators form adhesion, which can effectively increase the friction between the interfaces of the separators, and thus reduce the risk of pulling out the separators when the winding needle is pulled out; on the other hand, after the fusion body is cooled, the initial winding part increases the overall hardness through crystallization, which can provide a certain support effect on the electrode assembly. In addition, the electrode assembly preparation device in the present application only needs to add a hot blanching device near the winding needle of the conventional winding mechanism to achieve hot blanching fusion of the separator, without the need to modify the existing winding mechanism, and the setting method is simple and easy to use.

[0015] In some embodiments, the winding mechanism includes a winding needle, which is used to wind two pole pieces and a separator to form an electrode assembly, and the hot stamping device includes: a driving device having a retractable driving end, which is disposed toward the winding needle; a roller, which is configured to be rotatably disposed at the driving end; and a heating component, which is disposed at the driving end and is used to heat the roller. The roller can be detachably abutted against the winding needle under the drive of the driving end.

[0016] In this embodiment, during the separator winding process, the roller is arranged to fit the separator, thereby reducing the impact on the conventional winding of the separator and effectively ensuring the winding quality of the electrode assembly.

[0017] In some embodiments, the rotation axis direction of the roller is arranged parallel to the rotation axis direction of the winding needle.

[0018] In this embodiment, the parallel rollers can completely abut against the spacer wound by the winding needle in the direction of their rotation axis, so that the spacer can be heated more evenly during the winding and heating process, which is more conducive to the fusion of the spacer.

[0019] In some embodiments, the dimension of the roller along the rotation axis is equal to the dimension of the electrode assembly along the rotation axis of the winding needle.

[0020] In this embodiment, when the winding needle winds the isolation piece to form the initial winding portion, the roller can completely adhere to the entire length of the isolation piece along the direction of the rotating axis, so that the isolation piece can be completely heated in its axial direction, which can effectively reduce the occurrence of poor fusion problems caused by uneven heating of the isolation piece.

[0021] In some embodiments, the roller is configured to have a plurality of roller segments, and the plurality of roller segments are spaced apart along the direction of the rotation axis.

[0022] In this embodiment, the roller is constructed into several sub-rollers and arranged at intervals. On the one hand, it can effectively reduce the problem of difficulty in ensuring the straightness of the roller due to being too long, thereby reducing the problem of difficulty in uniform heating of the isolation piece due to poor straightness of the roller; on the other hand, if some of the sub-rollers among the several sub-rollers are defective, only the defective sub-rollers can be replaced, thereby also reducing the problem of the entire roller being unusable due to local defects.

[0023] In some embodiments, a plurality of annular roller teeth are formed on the outer peripheral wall surface of the roller, and the plurality of annular roller teeth are distributed at intervals along the rotation axis direction of the roller.

[0024] In this embodiment, the isolating element is heated by annular roller teeth that are distributed at intervals, and the thermally deformed portion of the isolating element after being heated can be accommodated in the gaps between the intervals. This can effectively prevent the thermally deformed portion from being pressed by the roller teeth, thereby causing the problem of uneven winding of the isolating element.

[0025] In some embodiments, the cross-sectional shapes of several annular roller teeth are configured to be rectangular and / or trapezoidal.

[0026] In this embodiment, the cross-sectional shapes of the annular roller teeth are diversified, so that the processing method of the annular roller teeth is more flexible.

[0027] In some embodiments, the heights of the plurality of annular roller teeth along the radial direction of the roller wheel are the same.

[0028] In this embodiment, a plurality of annular roller teeth of the same height can enable the roller to better adhere to the outer peripheral wall surface of the isolation member, thereby further improving the uniformity of heating of the isolation member.

[0029] In some embodiments, the heating temperature of the heating member ranges from 100°C to 200°C.

[0030] In this embodiment, by controlling the heating temperature range of the heating component to 100°C to 200°C, on the one hand, the problem of poor fusion of the isolation piece due to low temperature can be avoided; on the other hand, the problem of scalding and damage to the isolation piece due to excessively high temperature can be avoided.

[0031] In some embodiments, the driving pressure range of the driving device is less than or equal to 7 MPa.

[0032] In this embodiment, by setting the driving pressure range of the driving device to be less than or equal to 7 MPa, the problem of bending or breaking of the winding needle due to excessive pressure can be reduced.

[0033] In a third aspect, the present application provides a battery cell, comprising: the above-mentioned electrode assembly.

[0034] In a fourth aspect, the present application provides a battery, comprising the above-mentioned battery cell.

[0035] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0037] Figure 1 A schematic diagram of the exploded structure of a battery according to some embodiments of the present application;

[0038] Figure 2 A schematic diagram of the exploded structure of a battery cell according to some embodiments of the present application;

[0039] Figure 3 This is a schematic diagram of the structure of the electrode assembly of some embodiments of the present application;

[0040] Figure 4 This is a schematic diagram of the expanded structure of the electrode assembly of some embodiments of the present application;

[0041] Figure 5 A schematic diagram of the cross-sectional structure of an electrode assembly according to some embodiments of the present application;

[0042] Figure 6 It is a schematic structural diagram of an electrode assembly preparation device according to some embodiments of the present application, which shows the winding state of the initial winding portion;

[0043] Figure 7 It is a structural schematic diagram of an electrode assembly preparation device according to some embodiments of the present application, which shows a state where the winding of the initial winding portion is completed;

[0044] Figure 8 It is a structural schematic diagram of an electrode assembly preparation device according to some embodiments of the present application, which shows the winding state of the electrode assembly;

[0045] Fig. 9 A schematic diagram of the structure of a blanching device in some embodiments of the present application;

[0046] Fig.10 A schematic diagram of the structure of the rollers in some embodiments of the present application;

[0047] Fig.11 It is a schematic diagram of the structure of rollers in other embodiments of the present application;

[0048] Fig.12 for Fig.10 The enlarged schematic diagram of the structure at D of the roller shown, wherein a schematic diagram of the cross-sectional shape of the annular roller teeth of some embodiments of the present application is shown;

[0049] Fig.13 for Fig.10The enlarged schematic diagram of the structure at D of the roller shown shows schematic diagrams of the cross-sectional shape of the annular roller teeth in other embodiments of the present application. DETAILED DESCRIPTION

[0050] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0052] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0053] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0054] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0055] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0056] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0057] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0058] At present, from the perspective of market development, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of power batteries, the market demand is also constantly expanding.

[0059] The applicant has noticed that the electrode assembly in the battery cell is usually formed by winding with a winding needle, and the electrode assembly is wound into a roll structure and then put into a shell for use. However, when the electrode assembly is wound and the winding needle is pulled out, the winding needle often brings out the separator, especially the part of the separator that is empty-wound in the initial stage of winding the electrode assembly, resulting in poor alignment of the electrode assembly and making it unusable. The main reason why the winding needle brings out the separator is that after the winding needle completes the empty winding of the separator, the friction between the separator and the winding needle is slightly greater than the friction between the interfaces of the separator, so the separator is brought out when the needle is pulled out, which easily causes poor overall alignment of the electrode assembly, thereby affecting subsequent installation and use. Such problems are particularly prominent in the winding process of the electrode assembly of long cylindrical batteries.

[0060] In order to alleviate the problem of poor needle pulling, the applicant has found that the friction between the separator interfaces can be increased when the needle is empty. Based on the above considerations, the inventor has conducted in-depth research and designed an electrode assembly that fuses at least part of the separators in the initial section into one piece when they are empty, so as to increase the friction between the separator interfaces. In this way, when the needle is pulled out, the needle is not likely to pull out the separator because the friction between the separators is increased and the structure is an integrated structure.

[0061] The battery cells disclosed in the embodiments of the present application can be used, but not limited to, in electrical devices such as vehicles, ships or aircraft. A power supply system comprising the battery cells and batteries disclosed in the present application can be used to form the electrical device.

[0062] The embodiment of the present application provides an electric device using a battery as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0063] Please refer to Figure 1 , Figure 1 An exploded view of a battery 100 provided in some embodiments of the present application. The battery 100 includes a housing 10 and a battery cell 20, and the battery cell 20 is contained in the housing 10. The housing 10 is used to provide a storage space for the battery cell 20, and the housing 10 can adopt a variety of structures. In some embodiments, the housing 10 can include a first part 11 and a second part 12, and the first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define a storage space for accommodating the battery cell 20. The second part 12 can be a hollow structure with one end open, and the first part 11 can be a plate-like structure, and the first part 11 covers the open side of the second part 12, so that the first part 11 and the second part 12 jointly define a storage space; the first part 11 and the second part 12 can also be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12. Of course, the housing 10 formed by the first part 11 and the second part 12 can be in a variety of shapes, such as a cylinder, a cuboid, etc.

[0064] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a mixed connection. A mixed connection means that the multiple battery cells 20 are both connected in series and in parallel. The multiple battery cells 20 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 20 is accommodated in the box 10; of course, the battery 100 may also be a battery module formed by connecting multiple battery cells 20 in series, in parallel, or in a mixed connection, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 10. The battery 100 may also include other structures, for example, the battery 100 may also include a busbar component for realizing electrical connection between the multiple battery cells 20.

[0065] Each battery cell 20 may be a secondary battery or a primary battery, or a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0066] Please refer to Figure 2 , Figure 2 The schematic diagram of the exploded structure of the battery cell 20 provided in some embodiments of the present application. The battery cell 20 refers to the smallest unit that constitutes the battery. Figure 2 The battery cell 20 includes an end cover 21, a shell 22, an electrode assembly 23 and other functional components.

[0067] The end cap 21 refers to a component that covers the opening of the shell 22 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 21 can be adapted to the shape of the shell 22 to match the shell 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 21 is not easily deformed when squeezed and collided, so that the battery cell 20 can have a higher structural strength and the safety performance can also be improved. Functional components such as electrode terminals 21a can be provided on the end cap 21. The electrode terminal 21a can be used to electrically connect to the electrode assembly 23 for outputting or inputting electrical energy of the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The material of the end cap 21 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not impose special restrictions on this. In some embodiments, an insulating member may be provided inside the end cap 21, and the insulating member may be used to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. For example, the insulating member may be plastic, rubber, or the like.

[0068] The shell 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 23, the electrolyte and other components. The shell 22 and the end cap 21 can be independent components, and an opening can be set on the shell 22, and the internal environment of the battery cell 20 is formed by covering the opening with the end cap 21 at the opening. Without limitation, the end cap 21 and the shell 22 can also be integrated. Specifically, the end cap 21 and the shell 22 can form a common connection surface before other components are put into the shell, and when the interior of the shell 22 needs to be encapsulated, the end cap 21 covers the shell 22. The shell 22 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 22 can be determined according to the specific shape and size of the electrode assembly 23. The material of the shell 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.

[0069] The electrode assembly 23 is a component in the battery cell 100 where electrochemical reactions occur. One or more electrode assemblies 23 may be included in the housing 22. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active materials constitute the main body of the electrode assembly, and the parts of the positive and negative electrode sheets without active materials each constitute a tab. The positive tab and the negative tab may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive active material and the negative active material react with the electrolyte, and the tabs connect the electrode terminals to form a current loop.

[0070] Please refer to Figures 3 to 5 , Figure 3 This is a schematic diagram of the structure of the electrode assembly 23 in some embodiments of the present application; Figure 4 Schematic diagram of the expanded structure of the electrode assembly 23 in some embodiments of the present application; Figure 5 Schematic diagram of the cross-sectional structure of the electrode assembly 23 in some embodiments of the present application. Figures 3 to 5 As shown, the present application provides an electrode assembly 23, including a separator 24 and two pole pieces 25 with opposite polarities, the two pole pieces 25 and the separator 24 are wound to form the electrode assembly 23. The separator 24 is configured to have an initial winding portion 26, which is wound at the center of the electrode assembly 23, and at least part of the initial winding portion 26 is configured to be fused by the separator 24.

[0071] The two pole pieces 25 with opposite polarities mentioned in the present application should be understood as positive pole pieces and negative pole pieces. The separator 24 mentioned in the present application can be understood as the separator in the prior art. The initial winding portion 26 mentioned in the present application can be understood as the portion in which the separator 24 is pre-wound before the positive and negative pole pieces are fed into the winding process of the electrode assembly 23. The electrode assembly 23 mentioned in the present application can be constructed as a roughly oblong or cylindrical structure, and applied to square-shell battery cells 20, cylindrical battery cells 20 or other battery cells that can accommodate the wound electrode assembly 23. The center position thereof can be understood as the axis area of ​​the winding structure. The fusion mentioned in the present application can be achieved by heating, pressing and other processes on the initial winding portion 26 during the winding process and cooling it.

[0072] In the present application, when the electrode assembly 23 is wound, the initial winding portion 26 is first wound, that is, as the winding needle 201 of the winding mechanism 200 rotates, the separator 24 is first pre-constructed into a stacked winding layer. In this process, the separator 24 is heated by an external heating device, so that the separator 24 of the heated portion of the initial winding portion 26 gradually softens, and the softened separator 24 is more adhered to the winding layers during winding. After the separator 24 is wound for a preset number of turns, the external heating device is disengaged, and the electrode assembly 23 performs subsequent winding work. After the heated separator 24 cools, the separator 24 of this part will be attached as a whole and crystallized and hardened to finally be constructed into a fusion body. Through this arrangement, on the one hand, after the fusion body is cooled, the adjacent isolation members 24 form adhesions which can effectively increase the friction between the interfaces of the isolation members 24, thereby reducing the risk of pulling out the isolation members 24 when the winding needle 201 is pulled out; on the other hand, after the fusion body is cooled, the overall hardness can be increased through crystallization, thereby providing a certain supporting effect on the electrode assembly 23.

[0073] In some embodiments, the number of turns of the separator 24 of the initial winding portion 26 may range from 3 to 10 turns. The number of turns mentioned in the present application may generally be an integer number of turns, and in practice, the initial winding portion 26 may also be set to a non-integer number of turns greater than 1 turn according to the structure of the electrode assembly 23 and the need to control the battery capacity. With this setting, the number of turns of the separator 24 of the initial winding portion 26 is within the range of 3 to 10 turns, which effectively increases the friction between the interfaces of adjacent separators 24 while also reducing the occupied space of the initial winding portion 26, thereby effectively ensuring the overall effective volume of the electrode assembly 23.

[0074] In some embodiments, the diameter size of the initial winding portion 26 may range from 0.1 mm to 4 mm. The diameter size mentioned in the present application may be understood as the difference between the diameter of the outer surface of the winding needle and the winding diameter after the initial winding portion 26 is wound and before the positive and negative electrode sheets are fed, that is, the thickness range of the separator 24 in the initial winding portion 26. Similarly, through this setting, the diameter size of the initial winding portion 26 is within the range of 0.1 mm to 4 mm, which can increase the friction between the interfaces of adjacent separators 24 while reducing the occupied space of the initial winding portion 26, thereby effectively ensuring the overall effective volume of the electrode assembly 23.

[0075] Please refer to Figure 5 In some embodiments, the separator 24 may include a first separator 242 and a second separator 241; the electrode assembly 23 is configured such that: in the winding structure after the initial winding portion 26, the negative electrode sheet is inserted between the first separator 242 and the second separator 241, and in the subsequent winding structure, the positive electrode sheet is inserted between the first separator 242 and the second separator 241.

[0076] The initial winding portion 26 mentioned in the present application is formed by winding only the first separator 242 and the second separator 241 at the same time. The electrode assembly 23 mentioned in the present application usually includes the first separator 242, the positive electrode sheet, the second separator 241, and the negative electrode sheet in sequence. In the prior art, during the production process of the separator 24, the first separator 242 and the second separator 241 are cut and processed at the same time, and usually the ends of the first separator 242 and the second separator 241 are cut to be consistent. In the present application, by winding the first separator 242 and the second separator 241 into the initial winding portion 26 at the same time, the winding of the separator 24 can be facilitated, thereby further reducing the winding difficulty of the electrode assembly 23; at the same time, by winding the first separator 242 and the second separator 241 into the initial winding portion 26 at the same time, the hardness of the initial winding portion 26 can be improved by a separator 24 with fewer turns. In addition, in the present application, the negative electrode sheet is first inserted into the first separator 242 and the second separator 241 for winding. After winding for a certain length, for example, a distance greater than 0.1 turns, the positive electrode sheet is then inserted for winding, which can also effectively avoid lithium plating.

[0077] Please refer to Figures 6 to 9 , Figure 6 It is a structural schematic diagram of an electrode assembly preparation device 2000 according to some embodiments of the present application, which shows the winding state of the initial winding portion 26; Figure 7 is a schematic structural diagram of an electrode assembly preparation device 2000 according to some embodiments of the present application, which shows a state where the initial winding portion 26 is completed; Figure 8is a schematic structural diagram of an electrode assembly preparation device 2000 of some embodiments of the present application, which shows the winding state of the electrode assembly 23; Fig. 9 Schematic diagram of the structure of the blanching device 300 of some embodiments of the present application. Figures 6 to 9 As shown, the present application provides an electrode assembly preparation device 2000, comprising: a winding mechanism 200, used to wind a separator 24 and two pole pieces 25 with opposite polarities to form an electrode assembly 23, wherein the separator 24 is configured to have an initial winding portion 26, which is wound at the center of the electrode assembly 23. The winding mechanism 200 includes a hot stamping device 300, which is used to detachably abut against the winding mechanism 200 to fuse at least part of the initial winding portion 26.

[0078] The winding mechanism 200 mentioned in the present application can be understood as a winding machine used for winding the electrode assembly 23. The blanching device 300 mentioned in the present application is configured to be able to detachably abut against the winding mechanism 200, wherein it should be understood that since the winding needle 201 is used to wind the electrode assembly 23 in the winding mechanism 200, the blanching device 300 in the present application should be configured to detachably abut against the winding needle 201 of the winding mechanism 200. The blanching device 300 mentioned in the present application means that it can reach a preset temperature and can heat the separator 24 when abutting against the separator 24.

[0079] When the electrode assembly preparation device 2000 in the present application is used, the blanching device 300 is started and preheated. Before the winding starts, the blanching device 300 abuts against the separator 24 to be wound and starts heating. The winding mechanism 200 is turned on, and the winding needle 201 in the winding mechanism 200 winds the separator 24. After the separator 24 is wound for a preset number of turns, the blanching device 300 is controlled to disengage from the separator 24, and the winding mechanism 200 continues to wind the subsequent electrode assembly 23 to finally complete the winding of the electrode assembly 23.

[0080] Through the above-mentioned settings, the electrode assembly preparation device 2000 in the present application heats the separator 24 by setting a blanching device 300, and the attached winding after heating can form adhesion after cooling to form a fusion body. In this way, on the one hand, after the fusion body is cooled, the adjacent separators 24 form adhesion, which can effectively increase the friction between the interfaces of the separators 24, and thus reduce the risk of bringing out the separators 24 when the winding needle 201 is withdrawn; on the other hand, after the fusion body is cooled, the initial winding portion 26 increases the overall hardness through crystallization, so that it can play a certain supporting effect on the electrode assembly 23. In addition, the electrode assembly preparation device 2000 in the present application only needs to add a blanching device 300 near the winding needle 201 of the conventional winding mechanism 200 to achieve the blanching fusion of the separator 24, without the need to modify the existing winding mechanism 200, and the setting method is simple and easy to use.

[0081] Please refer to Figures 6 to 8 In some embodiments, the winding mechanism 200 may include a winding needle 201, which is used to wind the two pole pieces 25 and the separator 24 to form the electrode assembly 23. Fig. 9 and Fig.10 The hot stamping device 300 may include: a driving device 301 having a retractable driving end, the driving end being disposed toward the winding needle 201; a roller 302 configured to be rotatably disposed at the driving end; and a heating component 303 disposed at the driving end for heating the roller 302. The roller 302 can be detachably abutted against the winding needle 201 under the drive of the driving end.

[0082] The driving device 301 mentioned in the present application can be understood as a telescopic mechanism, such as a piston cylinder driven by air pressure or hydraulic pressure, or other mechanical devices capable of achieving telescopic movement, and the roller 302 is rotatably arranged at the end of the telescopic rod 304 of the telescopic mechanism. The roller 302 mentioned in the present application is movably arranged at the end of the telescopic rod 304 through a rotating shaft. The heating component 303 mentioned in the present application can be arranged in the rotating shaft to heat the roller 302. The driving device 301 mentioned in the present application can be connected to a control system to automatically control the separation and abutment of the roller 302.

[0083] When the electrode assembly preparation device 2000 in the present application is in use, the roller 302 is first heated by the heating component 303. After heating to a preset temperature, the driving device 301 is controlled to drive the roller 302 to abut against the winding needle 201. The winding mechanism 200 is started, and the winding needle 201 starts to rotate and winds the isolation member 24. During the winding process, the roller 302 adheres to the isolation member 24 and moves relative to it synchronously, while heating the isolation member 24. After the isolation member 24 is wound for a preset number of turns, the driving device 301 drives the roller 302 to disengage from the isolation member 24. The winding needle 201 continues the subsequent winding work to form the final electrode assembly 23. During the winding process of the isolation member 24, the present application reduces the influence of the conventional winding of the isolation member 24 by setting the roller 302 to fit the isolation member 24, thereby effectively ensuring the winding quality of the electrode assembly 23.

[0084] In some embodiments, the rotation axis direction of the roller 302 is arranged parallel to the rotation axis direction of the winding needle 201 .

[0085] The roller 302 and the winding needle 201 mentioned in the present application are arranged in parallel, which can also be understood as the axis of the rotating shaft of the roller 302 being arranged in parallel with the rotation axis direction of the winding needle 201. With this arrangement, the parallel roller 302 can completely abut against the isolation member 24 wound by the winding needle 201 in the direction of its rotation axis. In this way, the isolation member 24 can be heated more evenly during the winding heating process, which is more conducive to the fusion of the isolation member 24.

[0086] In some embodiments, the dimension of the roller 302 along the rotation axis is equal to the dimension of the electrode assembly 23 along the rotation axis of the winding needle 201 .

[0087] The size of the roller 302 mentioned in the present application is equal to the size of the electrode assembly 23, which can be understood as the size of the roller 302 along the rotation axis direction is equal to the size of the initial winding portion 26 after winding by the winding needle 201. Through this configuration, when the winding needle 201 winds the separator 24 to form the initial winding portion 26, the roller 302 can completely adhere to the entire length of the separator 24 along the direction of the rotation axis, so that the separator 24 can be completely heated in its axial direction, which can effectively reduce the occurrence of poor fusion caused by uneven heating of the separator 24.

[0088] Please refer to Fig.11 In other embodiments, the roller 302 is constructed to have a plurality of segment rollers 302a, and the plurality of segment rollers 302a are arranged at intervals along the direction of the rotation axis.

[0089] The several segments of sub-rollers 302a mentioned in the present application are all rotatably arranged on the rotating shaft of the driving end of the driving device 301, so that the several segments of sub-rollers 302a are coaxially arranged. The several segments mentioned in the present application may be n segments as shown in the figure. The interval setting mentioned in the present application can be understood as a plurality of mounting segments formed on the rotating shaft, which can be used to limit each sub-roller 302a, so that each sub-roller 302a is arranged at intervals. Through this setting, the winding mechanism 200 of the present application can generally be applied to wide-width battery cells 20, that is, the length of the battery cells 20 is generally 100 mm. In this way, the roller 302 is constructed into several sub-rollers 302a and arranged at intervals. On the one hand, it can effectively reduce the problem of difficulty in ensuring the straightness of the roller 302 due to being too long, thereby reducing the problem of difficulty in uniformly heating the isolation member 24 due to the poor straightness of the roller 302; on the other hand, if some of the sub-rollers 302a among the several sub-rollers 302a are defective, only the defective sub-roller 302a can be replaced, thereby reducing the problem of the entire roller 302 being unusable due to local defects.

[0090] Please refer to Fig.10 In some embodiments, a plurality of annular roller teeth 3021 are formed on the outer peripheral wall surface of the roller 302 , and the plurality of annular roller teeth 3021 are distributed at intervals along the rotation axis direction of the roller 302 .

[0091] The annular roller teeth 3021 mentioned in the present application can be understood as a convex portion formed along the circumferential direction of the outer peripheral wall surface of the roller wheel 302. In the present application, the spacer 24 is heated by the annular roller teeth 3021 distributed at intervals, and the heat-deformed portion of the spacer 24 after being heated can be accommodated in the gaps between the intervals, which can effectively prevent the heat-deformed portion from being rolled by the roller teeth, thereby causing the spacer 24 to be unevenly wound.

[0092] Please refer to Fig.12 and Fig.13 , Fig.12 for Fig.10 The enlarged schematic diagram of the structure at D of the roller shown, wherein a schematic diagram of the cross-sectional shape of the annular roller teeth of some embodiments of the present application is shown; Fig.13 for Fig.10 The enlarged schematic diagram of the structure at D of the roller shown in the figure shows the schematic diagram of the cross-sectional shape of the annular roller teeth of other embodiments of the present application. Among them, the cross-sectional shape of several annular roller teeth 3021 is configured as a rectangle and / or a trapezoid.

[0093] The cross-sectional shape of the annular roller teeth 3021 mentioned in the present application can be understood as the cross-sectional shape of the annular roller teeth 3021 along the radial direction of the roller 302. The cross-sectional shape of the annular roller teeth 3021 mentioned in the present application is rectangular and / or trapezoidal, and the and / or can be understood as the cross-sectional shapes of the annular roller teeth 3021 of the same roller 302 can all be rectangular, can all be trapezoidal, or can be rectangular and trapezoidal at the same time. In the present application, the cross-sectional shapes of the annular roller teeth 3021 are diversified, making the processing method of the annular roller teeth 3021 more flexible.

[0094] In some embodiments, the heights of the plurality of annular roller teeth 3021 along the radial direction of the roller wheel 302 are the same. With this arrangement, the plurality of annular roller teeth 3021 with the same height can make the roller wheel 302 better adhere to the outer peripheral wall surface of the isolation member 24, thereby further improving the uniformity of heating of the isolation member 24.

[0095] In some embodiments, the heating temperature of the heating member 303 ranges from 100°C to 2000°C.

[0096] The heating temperature mentioned in the present application can be understood as the temperature at which the roller 302 adheres to the spacer 24 and heats the spacer 24. In the present application, by controlling the heating temperature range of the heating component 303 to be 100°C to 2000°C, on the one hand, the problem of poor fusion of the spacer 24 due to low temperature can be avoided; on the other hand, the problem of scalding and damage to the spacer 24 due to excessively high temperature can be avoided.

[0097] In some embodiments, the driving pressure range of the driving device 301 is less than or equal to 7 MPa.

[0098] The driving pressure of the driving device 301 mentioned in the present application can be understood as the pressure when the roller 302 abuts against the isolation member 24 under the drive of the driving device 301. In the present application, by setting the driving pressure range of the driving device 301 to be less than or equal to 7 MPa, the problem of bending or breaking of the winding needle 201 due to excessive pressure can be reduced.

[0099] Please refer to Figure 2 The third aspect of the present application provides a battery cell 20 including: the above-mentioned electrode assembly 23.

[0100] Please refer to Figure 1 The fourth aspect of the present application provides a battery 100 including the above-mentioned battery cell 20.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: The electrode assembly comprises an isolating member and two pole pieces with opposite polarities, and the two pole pieces and the isolating member are wound to form the electrode assembly; The isolating member is configured to have an initial winding portion, which is wound at the center of the electrode assembly and located upstream of the winding starting end of the pole piece along the winding direction. At least part of the initial winding portion is configured to be formed by hot-melting and fusing multiple turns of the isolating member.

2. The battery cell according to claim 1, characterized in that: The number of turns of the separator in the initial winding portion ranges from 3 to 10 turns.

3. The battery cell according to claim 1, characterized in that: The diameter of the initial winding portion ranges from 0.1 mm to 4 mm.

4. The battery cell according to any one of claims 1 to 3, characterized in that: The separator includes a first separator and a second separator; the electrode assembly is configured such that: in a winding structure after the initial winding portion, a negative electrode sheet is inserted between the first separator and the second separator, and in a subsequent winding structure, a positive electrode sheet is inserted between the first separator and the second separator.

5. An electrode assembly preparation device, characterized in that: include: A winding mechanism, used for winding a separator and two pole pieces with opposite polarities to form an electrode assembly, wherein the separator is configured to have an initial winding portion, which is wound at a central position of the electrode assembly and is located upstream of a winding start end of the pole piece along a winding direction; Wherein, the winding mechanism comprises a hot-scalding device, and the hot-scalding device is used to detachably abut against the winding mechanism to fuse at least part of the initial winding portion.

6. The electrode assembly preparation device according to claim 5, characterized in that: The winding mechanism comprises a winding needle, and the winding needle is used to wind the two pole pieces and the separator to form the electrode assembly. The hot stamping device comprises: A driving device having a retractable driving end, wherein the driving end is disposed toward the winding needle; A roller wheel configured to be rotatably disposed at the driving end; and A heating component, disposed at the driving end, for heating the roller; Wherein, the roller can be detachably abutted against the winding needle under the drive of the driving end.

7. The electrode assembly preparation device according to claim 6, characterized in that: The rotation axis direction of the roller is arranged parallel to the rotation axis direction of the winding needle.

8. The electrode assembly preparation device according to claim 6, characterized in that: The dimension of the roller along the rotation axis direction is equal to the dimension of the electrode assembly along the rotation axis direction of the winding needle.

9. The electrode assembly preparation device according to claim 6, characterized in that: The roller is configured to have a plurality of roller segments, and the plurality of roller segments are arranged at intervals along the direction of the rotation axis.

10. The electrode assembly preparation device according to claim 6, characterized in that: A plurality of annular roller teeth are formed on the outer peripheral wall surface of the roller, and the plurality of annular roller teeth are distributed at intervals along the rotation axis direction of the roller.

11. The electrode assembly preparation device according to claim 10, characterized in that: The cross-sectional shapes of several of the annular roller teeth are configured to be rectangular and / or trapezoidal.

12. The electrode assembly preparation device according to claim 10, characterized in that: The heights of the plurality of annular roller teeth along the radial direction of the roller wheel are the same.

13. The electrode assembly preparation device according to any one of claims 6 to 12, characterized in that: The heating temperature of the heating component ranges from 100°C to 200°C.

14. The electrode assembly preparation device according to any one of claims 6 to 12, characterized in that: The driving pressure range of the driving device is less than or equal to 7 MPa.

15. A battery, characterized in that: The invention comprises a battery cell as claimed in any one of claims 1 to 4.

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