Method for manufacturing electrode assembly, electrode assembly, battery cell and related device

Abstract

The invention relates to the technical field of batteries, and provides a manufacturing method of an electrode assembly, the electrode assembly, a battery cell and a related device, and the manufacturing method of the electrode assembly comprises the following steps: providing an isolating membrane, a negative pole piece and a positive pole piece; cutting off the positive pole piece; providing a soft first connecting piece, covering the first connecting piece on the corresponding cut-off part of the positive pole piece, and connecting the first connecting piece with the cut-off positive pole piece to form a whole; feeding the isolating membrane, the negative pole piece and the positive pole piece into a winding mechanism for winding to form an electrode assembly winding body; performing shaping treatment on the electrode assembly winding body to obtain an electrode assembly of a flat structure; wherein the electrode assembly is provided with a straight area and bending areas located at the two opposite ends of the straight area, and at least part of the first connecting piece is located in the bending areas; according to the electrode assembly obtained by the manufacturing method of the electrode assembly provided by the invention, the probability of breakage of the positive pole piece is lower, and the reliability of the electrode assembly is higher.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular provides a method for manufacturing an electrode assembly, an electrode assembly, a battery cell, and related devices. Background Art

[0002] In recent years, new energy vehicles have experienced rapid development. In the electric vehicle sector, power batteries are core components used to provide electrical energy. Therefore, batteries have high requirements in terms of service life and safety.

[0003] The battery cells within the battery are formed by inserting the electrode assembly into the outer casing and then injecting the electrolyte. In related art, the electrode assembly is primarily manufactured by winding the assembly into a jellyroll and then shaping it into a flat structure. However, the electrode sheets of a flat electrode assembly have a significant degree of bending at the corners, making them more susceptible to breakage. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a method for manufacturing an electrode assembly, an electrode assembly, a battery cell and related devices, aiming to solve the problem in the related art that the pole pieces of the electrode assembly are prone to breakage at the corners of the ends.

[0005] To achieve the above objectives, the technical solutions adopted in the embodiments of the present application are: In a first aspect, an embodiment of the present application provides a method for manufacturing an electrode assembly, the method comprising: Provide separator, negative electrode sheet and positive electrode sheet; Cutting the positive electrode sheet; Providing a soft first connecting member, covering the corresponding cut portion of the positive electrode sheet, and connecting the first connecting member with the cut positive electrode sheet to form a whole; Feeding the separator, the negative electrode sheet and the positive electrode sheet into a winding mechanism for winding to form an electrode assembly winding body; The electrode assembly winding body is shaped to obtain an electrode assembly with a flat structure; wherein the electrode assembly has a straight area and bending areas located at opposite ends of the straight area, and at least a portion of the first connecting member is located in the bending area.

[0006] Beneficial effects of the embodiments of the present application: The manufacturing method of the electrode assembly provided in the embodiments of the present application is to cut the positive electrode sheet, cover the cut portion of the positive electrode sheet with a first connector, and connect them to form a whole. Moreover, after the electrode assembly is formed, at least a portion of the first connector is located in the bending area, and the soft first connector is used to replace the positive electrode sheet to bend and deform in the bending area, so that the probability of the positive electrode sheet breaking is lower, thereby reducing the probability of the positive electrode sheet breaking brittlely and puncturing the isolation membrane. At the same time, the first connector can also cover and protect the cut portion of the positive electrode sheet to cover and shield the burrs at the incision formed by the cutting of the positive electrode sheet, thereby effectively reducing the probability of the burrs piercing the isolation membrane and causing a short circuit, and the reliability of the electrode assembly is higher.

[0007] In some embodiments, the step of cutting the positive electrode sheet includes: In the winding direction of the winding mechanism, the first section of the positive electrode sheet is cut to form a positive electrode main body and at least one positive electrode laminate portion, and the at least one positive electrode laminate portion is located upstream of the positive electrode main body portion.

[0008] By adopting the above-mentioned technical solution, by operating the upstream first section of the positive electrode sheet along the winding direction, at least one positive electrode laminate portion formed by cutting is located upstream of the positive electrode main body portion along the winding direction of the winding mechanism, so that at least one positive electrode laminate portion can be wound into the interior of the electrode assembly winding body, so that the first connecting member connecting the positive electrode laminate portion and the positive electrode main body portion will also be located inside the electrode assembly winding body; when the electrode assembly winding body is shaped, the first connecting member can replace the positive electrode sheet for bending inside the electrode assembly winding body, which can effectively reduce the probability of brittle fracture of the positive electrode sheet.

[0009] In some embodiments, the step of shaping the electrode assembly jellyroll to obtain a flat electrode assembly includes: The negative electrode sheet includes a plurality of negative straight portions formed in the straight area, and at least one positive electrode lamination portion is located between any two adjacent negative straight portions.

[0010] By adopting the above technical solution, the positive electrode laminate portion can react with two adjacent negative electrode straight portions to form current.

[0011] In some embodiments, at least one positive electrode lamination portion is located between a first negative electrode straight portion and a second negative electrode straight portion of the plurality of negative electrode straight portions.

[0012] By adopting the above-mentioned technical solution, the positive electrode laminate portion can react with the first negative electrode straight portion and the second negative electrode straight portion at the same time to form current, which can effectively improve the utilization rate of the first negative electrode straight portion and the second negative electrode straight portion, thereby improving the energy density of the electrode assembly; at the same time, the positive electrode laminate portion is connected to other positive electrode laminate portions or positive electrode main portions through a first connecting member, and the first connecting member is located in the bending area and is located in the innermost circle of the winding body, with the greatest bending degree, which can replace the positive electrode sheet for bending and effectively reduce the probability of brittle fracture of the positive electrode sheet; at the same time, it can also reduce the risk of decomposition of the positive electrode sheet at the corner during use, which helps to improve the electrical performance of the electrode assembly.

[0013] In some embodiments, the step of cutting the positive electrode sheet includes: In the winding direction of the winding mechanism, the end section of the positive electrode sheet is cut to form a positive electrode main body and at least one positive electrode laminate portion, and the at least one positive electrode laminate portion is located downstream of the positive electrode main body portion.

[0014] By adopting the above-mentioned technical solution, at least one positive electrode laminate portion is arranged downstream of the positive electrode main body portion along the winding direction of the winding mechanism, so that at least one positive electrode laminate portion can be wound to the outside of the electrode assembly winding body, so that the positive electrode laminate portion located on the outside can be paired with the negative electrode sheets on the outer circle of other electrode assemblies to improve the overall energy density; at the same time, when the electrode assembly winding body is shaped, the first connecting member can replace the positive electrode sheet for bending, which can effectively reduce the probability of brittle fracture of the positive electrode sheet.

[0015] In some embodiments, the step of shaping the electrode assembly jellyroll to obtain a flat electrode assembly includes: The negative electrode sheet includes n negative electrode straight portions formed in the straight area; at least one positive electrode laminate portion is located between two adjacent negative electrode straight portions; and / or, at least one positive electrode laminate portion is wound to the outside of at least one of the nth negative electrode straight portion and the n-1th negative electrode straight portion of the n negative electrode straight portions.

[0016] By adopting the above-mentioned technical solution, at least one positive electrode laminate portion can be wound to the outside of the electrode assembly winding body, for example, the outside of at least one of the nth negative electrode straight portion and the n-1th negative electrode straight portion of n negative electrode straight portions, so that the positive electrode laminate can be used in pair with the outermost negative electrode sheet of other electrode assemblies; and / or, at least one positive electrode laminate portion can be wound between two adjacent negative electrode straight portions, and the positive electrode laminate and the two adjacent negative electrode straight portions are used to react to form current.

[0017] In some embodiments, before the step of feeding the separator, the negative electrode sheet, and the positive electrode sheet into a winding mechanism for winding to form an electrode assembly wound body, the method further includes: The positive electrode sheets are fed into a first buffer mechanism, in which positive electrode sheets of a preset length are cached; the first buffer mechanism is configured to maintain the rate at which the positive electrode sheets are fed into the winding mechanism by releasing the positive electrode sheets cached therein.

[0018] By adopting the above-mentioned technical solution, the first buffer mechanism can maintain the rate at which the positive electrode sheets are fed into the winding mechanism by releasing the internally cached positive electrode sheets, so as to reduce the impact on the transmission speed of the positive electrode sheets during the operation of cutting the positive electrode sheets or covering the first connecting piece, thereby effectively improving the production rate of the electrode assembly.

[0019] In some embodiments, before the step of feeding the separator, the negative electrode sheet, and the positive electrode sheet into a winding mechanism for winding to form an electrode assembly wound body, the method further includes: Cutting off the negative electrode; Providing a soft second connecting member, covering the corresponding cut portion of the negative electrode sheet, and connecting the second connecting member with the cut negative electrode sheet to form a whole; The steps of shaping the electrode assembly winding to obtain a flat electrode assembly include: At least a portion of the second connecting member is located in the bending zone.

[0020] By adopting the above-mentioned technical solution, the negative electrode sheet can be cut and then covered with a second connecting member at the corresponding cut portion and connected to form a whole, so that at least part of the second connecting member is located in the bending area when the electrode assembly is formed; in this way, the second connecting member can replace the negative electrode sheet to be bent in the bending area, thereby effectively reducing the probability of brittle fracture of the negative electrode sheet.

[0021] In some embodiments, the step of cutting the negative electrode sheet includes: In the winding direction of the winding mechanism, the first section of the negative electrode sheet is cut to form a negative electrode main body and at least one negative electrode laminate portion, and the at least one negative electrode laminate portion is located upstream of the negative electrode main body portion.

[0022] By adopting the above-mentioned technical solution, at least one negative electrode laminate portion is arranged upstream of the negative electrode main portion along the winding direction of the winding mechanism, so that at least one negative electrode laminate portion can be wound into the interior of the electrode assembly winding body, so that the second connecting member connecting the negative electrode laminate portion and the negative electrode main portion will also be located inside the electrode assembly winding body; when the electrode assembly winding body is shaped, the second connecting member can replace the negative electrode sheet for bending inside the electrode assembly winding body, which can effectively reduce the probability of brittle fracture of the negative electrode sheet.

[0023] In some embodiments, the step of shaping the electrode assembly jellyroll to obtain a flat electrode assembly includes: The negative electrode main body includes multiple negative electrode straight portions formed in the straight area, at least one negative electrode laminate portion and at least two positive electrode laminate portions are located between the first negative electrode straight portion and the second negative electrode straight portion among the multiple negative electrode straight portions, and positive electrode laminate portions are provided on the opposite sides of any negative electrode laminate portion.

[0024] By adopting the above-mentioned technical solution, at least one negative electrode laminate portion can be wound into the interior of the electrode assembly winding body, and positive electrode laminate portions are provided on both opposite sides of at least one negative electrode laminate portion, and the negative electrode laminate portion and the two adjacent positive electrode laminate portions are reacted to form current, and the positive electrode laminate portion reacts with the adjacent first negative electrode straight portion or the second negative electrode straight portion to form current, so as to improve the energy density of the electrode assembly; at the same time, the soft first connecting member and the soft second connecting member can be bent in the bending area to reduce the probability of brittle fracture of the positive electrode sheet and the negative electrode sheet.

[0025] In some embodiments, the step of cutting the negative electrode sheet includes: In the winding direction of the winding mechanism, the end section of the negative electrode sheet is cut to form a negative electrode main body and at least one negative electrode laminate portion, and the at least one negative electrode laminate portion is located downstream of the negative electrode main body portion.

[0026] By adopting the above-mentioned technical solution, at least one negative electrode laminate portion is arranged downstream of the negative electrode main body portion along the winding direction of the winding mechanism, so that at least one negative electrode laminate portion can be wound to the outside of the electrode assembly winding body; when the electrode assembly winding body is subjected to shaping processing, the second connecting member can replace the negative electrode sheet for bending, which can effectively reduce the probability of brittle fracture of the negative electrode sheet.

[0027] In some embodiments, the step of shaping the electrode assembly jellyroll to obtain a flat electrode assembly includes: The negative electrode main body includes n negative electrode straight portions formed in the straight area; at least one positive electrode laminate portion and at least one negative electrode laminate portion are located outside at least one of the nth negative electrode straight portion and the n-1th negative electrode straight portion of the n negative electrode straight portions.

[0028] By adopting the above-mentioned technical solution, at least one positive electrode laminate portion and at least one negative electrode laminate portion can be wound to the outside of the electrode assembly winding body, for example, the outside of at least one of the nth negative electrode straight portion and the n-1th negative electrode straight portion of n negative electrode straight portions, and the positive electrode laminate portion can be connected to the positive electrode main portion through the first connecting member, and the negative electrode laminate portion can be connected to the negative electrode main portion through the second connecting member, and the risk of breakage of the positive electrode sheet and the negative electrode sheet is lower.

[0029] In some embodiments, before the step of feeding the separator, the negative electrode sheet, and the positive electrode sheet into a winding mechanism for winding to form an electrode assembly wound body, the method further includes: The negative electrode sheet is fed into the second buffer mechanism, in which a negative electrode sheet of a preset length is cached; the second buffer mechanism is configured to maintain the rate at which the negative electrode sheet is fed into the winding mechanism by releasing the negative electrode sheet cached therein.

[0030] By adopting the above-mentioned technical solution, the second buffer mechanism can maintain the rate at which the negative electrode sheets are fed into the winding mechanism by releasing the internally cached negative electrode sheets, so as to reduce the impact on the transmission speed of the negative electrode sheets during the negative electrode sheet cutting operation or the covering operation of the second connecting piece, thereby effectively improving the production rate of the electrode assembly.

[0031] In some embodiments, the winding direction of the winding mechanism is clockwise; alternatively, the winding direction of the winding mechanism is counterclockwise.

[0032] By adopting the above technical solution, the winding direction of the winding mechanism can be set to a clockwise direction or a counterclockwise direction to obtain a corresponding electrode assembly winding body.

[0033] In some embodiments, the isolation membrane includes a first diaphragm and a second diaphragm; The step of feeding the separator, the negative electrode sheet and the positive electrode sheet into a winding mechanism and winding them to form an electrode assembly winding body includes: The negative electrode sheet is arranged on the top side of the first diaphragm, the second diaphragm is arranged on the top side of the negative electrode sheet, and the positive electrode sheet is arranged on the top side of the second diaphragm; The first separator, the second separator, the positive electrode sheet and the negative electrode sheet are fed into a winding mechanism and wound to form an electrode assembly winding body.

[0034] By adopting the above technical solution, the positive electrode sheet, the second separator, the negative electrode sheet and the first separator are arranged in sequence from the top side to the bottom side and sent into the winding mechanism to be wound to form an electrode assembly winding body, so that the corresponding electrode assembly winding body can be obtained.

[0035] In some embodiments, the first separator, the second separator, the positive electrode sheet, and the negative electrode sheet are fed into a winding mechanism and wound to form an electrode assembly wound body, including: Roll-compressing the negative electrode sheet and the first separator to form a first wound material; Rolling and compounding the positive electrode sheet and the second separator to form a second wound material; The first winding material and the second winding material are fed into a winding mechanism and wound to form an electrode assembly winding body.

[0036] By adopting the above-mentioned technical solution, the negative electrode sheet and the first diaphragm can be rolled and compounded to form a first wound material, and the positive electrode sheet and the second diaphragm can be rolled and compounded to form a second wound material, and then the first wound material and the second wound material can be fed into the winding mechanism and wound to form an electrode assembly wound body to improve the compactness of the electrode assembly wound body; wherein, after the positive electrode sheet is cut, it is connected to form a whole through the first connecting piece, so that the risk of the positive electrode sheet falling off from the second wound material due to cutting is lower.

[0037] In some embodiments, the isolation membrane includes a first diaphragm and a second diaphragm; The step of feeding the separator, the negative electrode sheet and the positive electrode sheet into a winding mechanism and winding them to form an electrode assembly winding body includes: The positive electrode sheet is arranged on the top side of the first diaphragm, the second diaphragm is arranged on the top side of the positive electrode sheet, and the negative electrode sheet is arranged on the top side of the second diaphragm; The first separator, the second separator, the positive electrode sheet and the negative electrode sheet are fed into a winding mechanism and wound to form an electrode assembly winding body.

[0038] By adopting the above technical solution, the negative electrode sheet, the second separator, the positive electrode sheet and the first separator are arranged in sequence from the top side to the bottom side and sent into the winding mechanism to be wound to form an electrode assembly winding body, so that the corresponding electrode assembly winding body can be obtained.

[0039] In some embodiments, the step of feeding the first separator, the second separator, the positive electrode sheet, and the negative electrode sheet into a winding mechanism to form an electrode assembly wound body includes: Roll-compressing the positive electrode sheet and the first separator to form a first wound material; Roll-compressing the negative electrode sheet and the second separator to form a second wound material; The first winding material and the second winding material are fed into a winding mechanism and wound to form an electrode assembly winding body.

[0040] By adopting the above-mentioned technical solution, the positive electrode sheet and the first diaphragm can be rolled and compounded to form a first wound material, and the negative electrode sheet and the second diaphragm can be rolled and compounded to form a second wound material, and then the first wound material and the second wound material can be fed into the winding mechanism and wound to form an electrode assembly wound body, so as to improve the compactness of the electrode assembly wound body; wherein, after the positive electrode sheet is cut, it is connected to form a whole through the first connecting piece, and the risk of the positive electrode sheet falling off from the first wound material due to cutting is lower.

[0041] In some embodiments, before the step of feeding the first winding material and the second winding material into the winding mechanism and winding them to form the electrode assembly wound body, the step includes: The first wound material and the second wound material are roll-compounded.

[0042] By adopting the above technical solution, the first wound material and the second wound material can be roll-compounded before the first wound material and the second wound material are wound to form the electrode assembly winding body, so as to further improve the compactness of the electrode assembly winding body.

[0043] In some embodiments, the step of feeding the first separator, the second separator, the positive electrode sheet, and the negative electrode sheet into a winding mechanism to form an electrode assembly wound body includes: Rolling and compounding the positive electrode sheet, the second separator and the negative electrode sheet to form a third wound material; The third winding material and the first separator are fed into the winding mechanism and wound to form an electrode assembly winding body.

[0044] By adopting the above-mentioned technical solution, the positive electrode sheet, the second separator and the negative electrode sheet can be rolled and composited to form a third wound material, and then the third wound material and the first separator are fed into the winding mechanism and wound to form an electrode assembly wound body, so as to improve the compactness of the electrode assembly wound body; at the same time, after the positive electrode sheet is cut, it is connected to form a whole through the first connecting piece, so that the risk of the cut positive electrode sheet falling after the composite operation is lower.

[0045] In some embodiments, the step of feeding the first separator, the second separator, the positive electrode sheet, and the negative electrode sheet into a winding mechanism to form an electrode assembly wound body includes: The first separator, the positive electrode sheet, the second separator and the negative electrode sheet are rolled and composited.

[0046] By adopting the above-mentioned technical solution, the positive electrode sheet, the second separator and the negative electrode sheet can be roll-combined and then sent to a winding mechanism to be wound to form an electrode assembly winding body, so as to improve the compactness of the electrode assembly winding body; at the same time, after the positive electrode sheet is cut, it is connected to form a whole through the first connecting piece, and the risk of the cut positive electrode sheet falling off after the composite operation is lower.

[0047] In some embodiments, the step of feeding the first separator, the second separator, the positive electrode sheet, and the negative electrode sheet into a winding mechanism to form an electrode assembly wound body includes: The positive electrode sheet, the negative electrode sheet, the first separator and the second separator are independently fed into the winding mechanism and wound to form an electrode assembly winding body.

[0048] By adopting the above-mentioned technical solution, the positive electrode sheet, the negative electrode sheet, the first diaphragm and the second diaphragm can be fed independently and fed into the winding mechanism to be wound to form an electrode assembly winding body; and after the positive electrode sheet is cut, it is connected to form a whole through the first connecting member, so that the integrity of the cut positive electrode sheet is better when it is wound, which can effectively reduce the probability of the cut positive electrode sheet becoming loose.

[0049] In a second aspect, an embodiment of the present application further provides an electrode assembly, which is prepared by the manufacturing method of the electrode assembly as described above.

[0050] Beneficial effects of the embodiments of the present application: The electrode assembly provided in the embodiments of the present application is prepared by adopting the above-mentioned manufacturing method of the electrode assembly, so that the reliability of the electrode assembly is better.

[0051] In a third aspect, an embodiment of the present application further provides a battery cell, which includes a housing and an electrode assembly as described above, wherein the electrode assembly is accommodated in the housing.

[0052] Advantageous effects of the embodiments of the present application: The battery cell provided by the embodiments of the present application, including the electrode assembly described above, has better reliability.

[0053] In a fourth aspect, an embodiment of the present application further provides a battery device, which includes the battery cell as described above.

[0054] Beneficial effects of the embodiments of the present application: The battery device provided by the embodiments of the present application includes the battery cells as described above, so that the reliability of the battery device is better.

[0055] In a fifth aspect, an embodiment of the present application further provides an electrical device, which includes the battery cell as described above, or includes the battery device as described above; the battery cell or the battery device is used to provide electrical energy.

[0056] Beneficial effects of the embodiments of the present application: The electrical device provided by the embodiments of the present application includes the battery cell or the battery device as described above, thereby improving the reliability of the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0058] Figure 1 A schematic diagram of the structure of a vehicle provided in an embodiment of the present application; Figure 2 An exploded view of a battery device provided in an embodiment of the present application; Figure 3 A schematic diagram of the exploded structure of a battery cell provided in an embodiment of the present application; Figure 4 A flowchart of a method for manufacturing an electrode assembly according to an embodiment of the present application; Figure 5A schematic diagram of a process for obtaining an electrode assembly through a method for manufacturing an electrode assembly provided in an embodiment of the present application; Figure 6 A schematic structural diagram of an electrode assembly obtained by a method for manufacturing an electrode assembly provided in an embodiment of the present application; Figure 7 A schematic structural diagram of another electrode assembly obtained by a method for manufacturing an electrode assembly provided in an embodiment of the present application; Figure 8 A schematic structural diagram of another electrode assembly obtained by a method for manufacturing an electrode assembly provided in an embodiment of the present application; Figure 9 A flowchart of the steps of another method for manufacturing an electrode assembly provided in an embodiment of the present application; Figure 10 A flowchart of the steps of another method for manufacturing an electrode assembly provided in an embodiment of the present application; Figure 11 A schematic diagram of another process for obtaining an electrode assembly through a manufacturing method of an electrode assembly provided in an embodiment of the present application; Figure 12 A schematic structural diagram of an electrode assembly obtained by a method for manufacturing an electrode assembly provided in an embodiment of the present application; Figure 13 A schematic structural diagram of another electrode assembly obtained by a method for manufacturing an electrode assembly provided in an embodiment of the present application; Figure 14 A schematic structural diagram of another electrode assembly obtained by a method for manufacturing an electrode assembly provided in an embodiment of the present application; Figure 15 A flowchart of the steps before feeding a separator, a negative electrode sheet, and a positive electrode sheet into a winding mechanism for winding to form an electrode assembly wound body is provided in an embodiment of the present application; Figure 16 A schematic diagram of another process for obtaining an electrode assembly through a manufacturing method of an electrode assembly provided in an embodiment of the present application; Figure 17 A flowchart of the specific steps of feeding a separator, a negative electrode sheet, and a positive electrode sheet into a winding mechanism for winding to form an electrode assembly wound body provided in an embodiment of the present application; Figure 18 A schematic diagram of another process for obtaining an electrode assembly through a manufacturing method of an electrode assembly provided in an embodiment of the present application; Figure 19 A schematic structural diagram of another electrode assembly obtained by a method for manufacturing an electrode assembly provided in an embodiment of the present application; Figure 20A flowchart of the specific steps of feeding a first separator, a second separator, a positive electrode sheet, and a negative electrode sheet into a winding mechanism for winding to form an electrode assembly wound body provided in an embodiment of the present application; Figure 21 A schematic diagram of another process for obtaining an electrode assembly through a manufacturing method of an electrode assembly provided in an embodiment of the present application; Figure 22 A flowchart of another embodiment of the present application showing the specific steps of feeding a separator, a negative electrode sheet, and a positive electrode sheet into a winding mechanism for winding to form an electrode assembly wound body; Figure 23 A flowchart of another embodiment of the present application showing the specific steps of feeding a first separator, a second separator, a positive electrode sheet, and a negative electrode sheet into a winding mechanism for winding to form an electrode assembly wound body; Figure 24 A schematic diagram of another process for obtaining an electrode assembly through a manufacturing method of an electrode assembly provided in an embodiment of the present application; Figure 25 A schematic structural diagram of another electrode assembly obtained by a method for manufacturing an electrode assembly provided in an embodiment of the present application; Figure 26 A flowchart of another embodiment of the present application showing the specific steps of feeding a first separator, a second separator, a positive electrode sheet, and a negative electrode sheet into a winding mechanism for winding to form an electrode assembly wound body; Figure 27 A schematic diagram of another process for obtaining an electrode assembly through a manufacturing method of an electrode assembly provided in an embodiment of the present application; Figure 28 A flowchart of another embodiment of the present application showing the specific steps of feeding a first separator, a second separator, a positive electrode sheet, and a negative electrode sheet into a winding mechanism for winding to form an electrode assembly wound body; Figure 29 A schematic diagram of another process for obtaining an electrode assembly through a manufacturing method of an electrode assembly provided in an embodiment of the present application; Figure 30 A schematic diagram of another process for obtaining an electrode assembly through a manufacturing method of an electrode assembly provided in an embodiment of the present application; Figure 31 A schematic diagram of another process for obtaining an electrode assembly through a manufacturing method of an electrode assembly provided in an embodiment of the present application; Figure 32 A flowchart of another method for manufacturing an electrode assembly according to an embodiment of the present application; Figure 33 A flowchart of the steps of another method for manufacturing an electrode assembly provided in an embodiment of the present application.

[0059] Among them, the reference numerals in the figures are: 1000. Vehicle; 100, battery device; 200, controller; 300, motor; 10. Box; 11. First box; 12. Second box; 20. Battery cell; 21. End cap; 21a. Electrode terminal; 22. Housing; 23. Electrode assembly; 230a. Straight region; 230b. Bend region; 23a. Tab; 231. Positive electrode sheet; 2311. Positive electrode body; 2312. Positive electrode lamination; 232. Negative electrode sheet; 232a. Negative straight portion; 232a1. First negative straight portion; 232a2. Second negative straight portion; 2321. Negative electrode body; 2322. Negative electrode lamination; 233. Separator; 2331. First separator; 2332. Second separator; 234. First connector; 235. Second connector; 236. First wound material; 237. Second wound material; 238. Third wound material; 2000, winding mechanism; S, winding direction; 3000, first buffer mechanism; 4000, second buffer mechanism. DETAILED DESCRIPTION

[0060] The following describes in detail embodiments of the present application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0061] In the description of this application, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0062] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0063] In this application, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components or interactions between two components. Those skilled in the art will understand the specific meanings of these terms in this application based on specific circumstances.

[0064] Currently, market developments indicate that power battery applications are becoming increasingly widespread. Power batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in industrial equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0065] The battery cells within the battery are formed by inserting the electrode assembly into the outer casing and then injecting the electrolyte. In related art, the electrode assembly is primarily manufactured by winding the assembly into a jellyroll and then shaping it into a flat structure. However, the electrode sheets of a flat electrode assembly have a significant degree of bending at the corners, making them more susceptible to breakage.

[0066] Based on the above considerations, in order to solve the problem in the related art that the electrode sheets of the electrode assembly are prone to breakage at the corners of the ends, a manufacturing method of the electrode assembly is designed. In this method, after the positive electrode sheet is cut, a soft first connecting member is used to cover the corresponding cut portion of the positive electrode sheet, and is connected to the cut positive electrode sheet to form a whole. After the positive electrode sheet is wound and shaped to form an electrode assembly, at least part of the first connecting member is located in the bending area; thus, the soft first connecting member is used to replace the positive electrode sheet and is set in the bending area for bending and deformation, so that the probability of the positive electrode sheet breaking is lower, thereby reducing the probability of the positive electrode sheet breaking brittlely and puncturing the isolation membrane, and the stability of the electrode assembly is better.

[0067] The battery device disclosed in the embodiments of the present application can be used in various energy storage systems that use the battery device as a power source or use the battery device as an energy storage element. The power device can be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, and the like. Among them, the electric toy can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like, and the spacecraft can include airplanes, rockets, space shuttles, and spacecraft, and the like.

[0068] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0069] Please refer to Figure 1 , Figure 1 A schematic structural diagram of a vehicle 1000 provided for some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery device 100 is provided inside the vehicle 1000. The battery device 100 may be provided at the bottom, head or tail of the vehicle 1000. The battery device 100 may be used to power the vehicle 1000. For example, the battery device 100 may serve as an operating power source for the vehicle 1000. The vehicle 1000 may further include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to power the motor 300, for example, for starting, navigating and operating power requirements of the vehicle 1000 during driving.

[0070] In some embodiments of the present application, the battery device 100 can serve not only as an operating power source for the vehicle 1000 , but also as a driving power source for the vehicle 1000 , replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000 .

[0071] Please refer to Figure 2 , Figure 2 An exploded view of a battery device 100 provided in some embodiments of the present application. The battery device 100 described in the embodiments of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assemblies may include multiple battery cells 20, which are connected in series, parallel, or in parallel via a busbar.

[0072] In some embodiments, a battery cell assembly is generally formed by arranging a plurality of battery cells 20 .

[0073] As an example, the battery cell assembly may be a battery module, which is formed by arranging and fixing a plurality of battery cells 20 to form an independent module. As an example, the battery module may be formed by bundling a plurality of battery cells 20 with a cable tie.

[0074] In some embodiments, the battery device may be a battery pack, which includes a case 10 and one or more battery cell assemblies, wherein the battery cell assemblies are housed in the case 10 .

[0075] As an example, the battery cell assembly may be a battery module, and the battery cell assembly may be accommodated in the box body 10 by fixing the battery module in the box body 10 .

[0076] As an example, the battery cell assembly may also be housed in the case 10 by directly fixing the plurality of battery cells 20 to the case 10 .

[0077] As an example, the housing 10 may include a first housing 11 and a second housing 12. The first housing 11 and the second housing 12 engage to form an enclosed space within the housing 10 for accommodating the battery cell assembly. Enclosed here means covered or closed, and can be either sealed or unsealed. The first housing 11 may be a top cover or a bottom plate.

[0078] As an example, the box body 10 may include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame, so that a closed space is formed inside the box body 10 to accommodate the battery cell assembly.

[0079] In some embodiments, the box 10 may serve as part of the chassis structure of the vehicle 1000. For example, a portion of the box 10 may form at least a portion of the floor of the vehicle 1000, or a portion of the box 10 may form at least a portion of the cross member and longitudinal member of the vehicle 1000.

[0080] The technical solutions described in the embodiments of the present application are applicable to various electrical devices that use battery cells 20, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, electric tools, vehicles, ships and spacecraft, etc. For example, spacecraft include airplanes, rockets, space shuttles and spacecraft, etc.

[0081] In the embodiment of the present application, the battery cell 20 may be a secondary battery. A secondary battery refers to a battery cell 20 that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0082] The battery cell 20 can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel metal hydride battery, a nickel cadmium battery, a lead storage battery, etc., which is not limited in the embodiment of the present application.

[0083] Please refer to Figure 3 , Figure 3 The following is a schematic diagram of the exploded structure of a battery cell 20 provided in some embodiments of the present application. The battery cell 20 refers to the smallest unit that constitutes a battery device. Figure 3 The battery cell 20 includes an end cap 21, a shell 22, an electrode assembly 23 and other functional components.

[0084] The end cap 21 is a component that fits over the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the end cap 21 can be adapted to the shape of the housing 22 to fit the housing 22. Optionally, the end cap 21 can be made of a material with a certain degree of hardness and strength (such as an aluminum alloy). This prevents deformation during compression and collision, providing the battery cell 20 with greater structural strength and improved safety. The end cap 21 can be equipped with functional components such as electrode terminals 21a. The electrode terminals 21a can be used to electrically connect to the electrode assembly 23 to transfer electrical energy to or from the battery cell 20. In some embodiments, the end cap 21 can also be equipped with a pressure relief mechanism to release internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The end cap 21 can also be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, and plastic. In some embodiments, an insulating member may be provided inside the end cap 21 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 made of plastic, rubber, or the like.

[0085] The housing 22 is a component that cooperates with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can be used to accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and end cap 21 can be separate components. An opening can be provided in the housing 22, and the end cap 21 is placed over the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and housing 22 can be integrated. Specifically, the end cap 21 and housing 22 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 22 needs to be enclosed, the end cap 21 is placed over the housing 22. The housing 22 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylinder, or a hexagonal prism. Specifically, the shape of the housing 22 can be determined based on the specific shape and size of the electrode assembly 23. The housing 22 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, and plastic.

[0086] The electrode assembly 23 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 23 may be contained 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 23a. The positive and negative electrode tabs 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 device 100, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tab 23a is connected to the electrode terminal 21a to form a current loop.

[0087] According to some embodiments of the present application, referring to Figures 4 to 6 , an embodiment of the present application provides a method for manufacturing an electrode assembly 23, the method comprising: Step S100, providing a separator 233, a negative electrode sheet 232 and a positive electrode sheet 231; Step S200, cutting the positive electrode sheet 231; Step S300: providing a soft first connecting member 234, covering the corresponding cut portion of the positive electrode sheet 231, and connecting the first connecting member 234 with the cut positive electrode sheet 231 to form a whole; Step S400: feeding the separator 233, the negative electrode sheet 232 and the positive electrode sheet 231 into the winding mechanism 2000 for winding to form an electrode assembly winding body; Step S500, shaping the electrode assembly winding to obtain an electrode assembly 23 with a flat structure; wherein the electrode assembly 23 has a straight area 230a and bending areas 230b located at opposite ends of the straight area 230a, and at least a portion of the first connecting member 234 is located in the bending area 230b.

[0088] In step S100 , the separator 233 , the negative electrode sheet 232 , and the positive electrode sheet 231 may be fed separately; illustratively, the separator 233 , the negative electrode sheet 232 , and the positive electrode sheet 231 may be unwound separately by an unwinding mechanism to achieve separate feeding.

[0089] Among them, the positive electrode plate 231 refers to a plate structure in which positive electrode active materials (such as positive ions, etc.) are coated on both sides of a substrate such as aluminum foil; the negative electrode plate 232 refers to a plate structure in which negative electrode active materials (such as negative ions, etc.) are coated on both sides of a substrate such as aluminum foil.

[0090] The separator 233 is used to separate the negative electrode 232 from the positive electrode 231. Furthermore, the separator 233 can be used to form an ion channel between the negative electrode 232 and the positive electrode 231, ensuring the transfer and reaction of positive and negative ions. Optionally, the separator 233 can be made of, but is not limited to, polypropylene or polyethylene.

[0091] In step S200 , the positive electrode sheet 231 is cut. Optionally, the positive electrode sheet 231 may be cut once, or may be cut twice or more.

[0092] In step S300, the first connector 234 is a flexible connecting structure; optionally, the first connector 234 may be, but is not limited to, adhesive tape, an insulating film layer, etc. It should be understood that the flexible first connector 234 does not risk breaking when bent at a large angle.

[0093] The first connecting member 234 is covered on the corresponding cut portion of the positive electrode plate 231, that is, the first connecting member 234 can be set at the corresponding cut portion and simultaneously connected to the two parts formed after cutting; in this way, the first connecting member 234 can cover the incisions of the two parts formed by cutting, so that the first connecting member 234 can cover the burrs generated at the incisions formed by cutting, thereby effectively reducing the risk of puncture of the isolation membrane 233 by the burrs at the incisions.

[0094] At the same time, the first connecting member 234 can also reconnect the two parts formed after cutting to form a whole. During the transmission and winding process, the structure connected to form a whole is less likely to have risks such as falling off and loosening; this can effectively improve the quality of the produced electrode assembly 23.

[0095] In step S400, the winding mechanism 2000 is a structure for winding the positive electrode sheet 231, the separator 233, and the negative electrode sheet 232. In some embodiments, the winding mechanism 2000 may include a winding needle for securing the positive electrode sheet 231, the separator 233, and the negative electrode sheet 232, as well as a holding member, a gluing member, a blanking member, and the like for finishing.

[0096] It should be understood that the positive electrode sheet 231, the isolation film 233 and the negative electrode sheet 232 can be fed into the winding mechanism 2000 separately and wound to form an electrode assembly wound body; or, the positive electrode sheet 231, the isolation film 233 and the negative electrode sheet 232 can be first rolled and composited and then fed into the winding mechanism 2000 and wound to form an electrode assembly wound body.

[0097] In step S500 , after the positive electrode sheet 231 , the separator 233 and the negative electrode sheet 232 are fed into the winding mechanism 2000 and wound into an electrode assembly wound body, the electrode assembly wound body may be shaped to obtain a flat electrode assembly 23 .

[0098] The shaping process refers to pressing and shaping the wound electrode assembly body so that the wound electrode assembly body forms a flat electrode assembly 23 .

[0099] It should be understood that after the electrode assembly winding body is shaped to obtain the electrode assembly 23 with a flat structure, the flat electrode assembly 23 will form a straight area 230a and bending areas 230b located at opposite ends of the straight area 230a.

[0100] The straight region 230a refers to the region of the electrode assembly 23 where the positive electrode tab 231 and the negative electrode tab 232 are formed into a straight shape after being shaped and pressed. The bent region 230b refers to the region of the electrode assembly 23 where the positive electrode tab 231 and the negative electrode tab 232 are formed into a bent shape after being shaped and pressed. It should be understood that the bent regions 230b are formed on opposite sides of the straight region 230a.

[0101] At least a portion of the first connector 234 is located in the bending region 230 b . Thus, the first connector 234 can replace the positive electrode sheet 231 in the bending region 230 b , and the first connector 234 replaces the positive electrode sheet 231 for bending and deformation.

[0102] Optionally, the first connector 234 can be completely located in the bending zone 230b, and a portion of the positive electrode tab 231 extends into the bending zone 230b or extends to the junction of the bending zone 230b and the straight zone 230a and is connected to the first connector 234; or, a portion of the first connector 234 can be located in the bending zone 230b, and at least one end of the first connector 234 extends into the straight zone 230a and is connected to the positive electrode tab 231.

[0103] For example, in some embodiments, taking the first connecting member 234 as adhesive tape, in a flat electrode assembly 23, the adhesive tape can be located in the bending area 230b, and the opposite ends of the adhesive tape are respectively located at the junction of the bending area 230b and the straight area 230a and adhered to the corresponding parts of the cut positive electrode plate 231; when the adhesive tape is bent and deformed at a large angle in the bending area 230b, due to the soft nature of the adhesive tape itself, the adhesive tape will not break and there will be no risk of puncturing the isolation membrane 233.

[0104] Optionally, a first connector 234 may be provided on either side of the positive electrode sheet 231 along the thickness direction and cover the cut portion; or, a first connector 234 may be provided on both opposite sides of the positive electrode sheet 231 along the thickness direction and cover the cut portion.

[0105] The manufacturing method of the electrode assembly 23 provided in the embodiment of the present application is to cut the positive electrode sheet 231, and then use the first connecting member 234 to cover the cut portion of the positive electrode sheet 231 and connect them to form a whole. Moreover, after the electrode assembly 23 is formed, at least a portion of the first connecting member 234 is located in the bending area 230b, and the soft first connecting member 234 is used to replace the positive electrode sheet 231 to be bent and deformed in the bending area 230b, so that the probability of the positive electrode sheet 231 breaking is lower, thereby reducing the probability of the positive electrode sheet 231 breaking brittlely and puncturing the isolation membrane 233; at the same time, the first connecting member 234 can also cover and protect the cut portion of the positive electrode sheet 231 to cover and shield the burrs at the incision formed by the cutting of the positive electrode sheet 231, thereby effectively reducing the probability of the burrs piercing the isolation membrane 233 and causing a short circuit, and the reliability of the electrode assembly 23 is higher.

[0106] Please refer to Figure 4 、 Figure 5 and Figure 7 In some embodiments, the step of cutting the positive electrode sheet 231 includes: In the winding direction of the winding mechanism 2000 , the first section of the positive electrode sheet 231 is cut to form a positive electrode main body 2311 and at least one positive electrode laminate 2312 . The at least one positive electrode laminate 2312 is located upstream of the positive electrode main body 2311 .

[0107] Among them, in the winding direction S of the winding mechanism 2000, the first section of the positive electrode sheet 231 refers to the upstream part of the positive electrode sheet 231 along the winding direction S; it should be understood that when the positive electrode sheet 231 is fed into the winding mechanism 2000 for winding, the first section of the positive electrode sheet 231 in the winding direction S is first fed into the winding mechanism 2000.

[0108] In this embodiment, the first section of the positive electrode sheet 231 in the winding direction S is cut, so that the positive electrode sheet 231 forms a positive electrode main portion 2311 and at least one positive electrode laminate portion 2312. It should be understood that because the cut is located at the first section of the positive electrode sheet 231 in the winding direction S, the shorter portion of the positive electrode sheet 231 formed after the cut will be located upstream of the longer portion, that is, the positive electrode laminate portion 2312 is located upstream of the positive electrode main portion 2311.

[0109] The positive electrode main body 2311 refers to the longer portion of the positive electrode sheet 231 after being cut. The positive electrode main body 2311 can be wound by the winding mechanism 2000 to form a winding structure with multiple turns.

[0110] Correspondingly, the positive electrode lamination portion 2312 refers to the shorter portion of the positive electrode sheet 231 after it is cut. After the electrode assembly 23 is formed, any positive electrode lamination portion 2312 is located only in one circle of the electrode assembly 23, such as the innermost circle, the middle circle, or any other position. Optionally, the number of positive electrode lamination portions 2312 can be one, two, or more than two; one or more positive electrode lamination portions 2312 are formed upstream of the positive electrode main body 2311 along the winding direction S.

[0111] Illustratively, in some embodiments, when a cutting operation is performed on the first section of the positive electrode sheet 231 in the winding direction S, the positive electrode sheet 231 will form a positive electrode main body 2311 and a positive electrode laminate portion 2312 located upstream of the positive electrode main body 2311; the first connecting member 234 is covered on the incision formed by the cutting operation, so that the first connecting member 234 simultaneously connects the positive electrode main body 2311 and the positive electrode laminate portion 2312 and connects them into one body, so as to facilitate subsequent transmission operations and winding operations.

[0112] When the first section of the positive electrode sheet 231 in the winding direction S is cut twice, the positive electrode sheet 231 will form a positive electrode main body 2311 and two positive electrode laminate parts 2312 located upstream of the positive electrode main body 2311; the two incisions formed by the two cutting operations are respectively covered with first connecting members 234, so that one first connecting member 234 connects the positive electrode main body 2311 and the positive electrode laminate part 2312 at the same time, and the other first connecting member 234 connects the two positive electrode laminate parts 2312 at the same time, so that the positive electrode main body 2311 and the two positive electrode laminate parts 2312 are connected to form a whole, so as to facilitate subsequent transmission operations and winding operations.

[0113] By analogy, when the first section of the positive electrode sheet 231 in the winding direction S is cut m times, the positive electrode sheet 231 will form a positive electrode main body 2311 and m positive electrode laminate parts 2312 located upstream of the positive electrode main body 2311, where m is a positive integer not less than 2; and, the m incisions formed after the m cutting operations are respectively covered with the first connecting member 234, so that the positive electrode main body 2311 and the m positive electrode laminate parts 2312 are connected to form a whole.

[0114] It should be understood that when there are multiple positive electrode lamination parts 2312 , the multiple positive electrode lamination parts 2312 can be arranged in sequence and spaced apart in a direction perpendicular to the straight portion.

[0115] In this way, by operating the first section upstream of the positive electrode sheet 231 along the winding direction S, at least one positive electrode laminate portion 2312 formed by cutting is located upstream of the positive electrode main body 2311 along the winding direction S of the winding mechanism 2000, so that at least one positive electrode laminate portion 2312 can be wound into the interior of the electrode assembly winding body, so that the first connecting member 234 connecting the positive electrode laminate portion 2312 and the positive electrode main body 2311 will also be located inside the electrode assembly winding body; when the electrode assembly winding body is shaped, the first connecting member 234 can replace the positive electrode sheet 231 to be bent inside the electrode assembly winding body, which can effectively reduce the probability of brittle fracture of the positive electrode sheet 231.

[0116] It's also important to note that when a lithium-ion battery is first charged, if the negative electrode is a graphite / carbon system, the reaction between the negative electrode and the electrolyte forms a SEI (solid electrolyte interface) film on the negative electrode surface. This SEI film acts as an ion conductor and an electronic insulator, allowing lithium ions to pass while blocking electrons. The SEI film is fundamental to the operation of lithium-ion batteries. In actual production, the formation of the SEI film requires the negative electrode to react with the electrolyte, and the operation of the lithium-ion battery is accompanied by the breakdown and repair of the SEI film. Therefore, when designing lithium-ion batteries, it is necessary to overdesign the negative electrode capacity. Specifically, the actual CB (the ratio of the product of the negative electrode areal density and the negative electrode gram capacity to the product of the positive electrode areal density and the positive electrode gram capacity) value should be greater than the designed CB value. This ensures that the negative electrode capacity meets the requirements for lithium-ion battery intercalation while providing sufficient graphite / carbon to react and form the SEI film. In actual production, if the negative electrode is under-designed (the actual CB value is less than the designed CB value), a significant short-circuit safety hazard may exist within the battery. During the actual manufacturing process, the curvature of the wound positive and negative electrode sheets 231 and 232 varies with different locations within the electrode assembly 23 (for example, the curvature of the electrode sheet located at the innermost circle of the bend 230b increases with the number of turns from the innermost circle of the bend 230b). Therefore, as the curvature of the positive and negative electrode sheets 231 and 232 changes, the actual CB values of the electrode sheets at different locations vary. Because the curvature of the electrode sheet significantly affects the CB value, locations within the electrode assembly 23 with greater curvature within the bend 230b are prone to negative electrode excess or deficiency. This means that the actual CB cannot be guaranteed to be greater than the designed CB value, which can easily lead to lithium deposition.

[0117] Thus, in this embodiment, by cutting the positive electrode sheet 231 and covering it with the first connecting member 234, and making the first connecting member 234 replace the positive electrode sheet 231 and set it in the bending area 230b for bending, the probability of excessive bending of the positive electrode sheet 231 in the bending area 230b can be effectively reduced, thereby effectively reducing the probability of insufficient CB value, and further effectively reducing the probability of lithium plating.

[0118] Please refer to Figure 4 、 Figure 5 and Figure 7 In some embodiments, the step of shaping the electrode assembly wound body to obtain the electrode assembly 23 with a flat structure includes: The negative electrode sheet 232 includes a plurality of negative straight portions 232 a formed in the straight region 230 a , and at least one positive electrode laminate portion 2312 is located between any two adjacent negative straight portions 232 a .

[0119] It should be understood that in step S400, when the isolation membrane 233, the negative electrode sheet 232 and the positive electrode sheet 231 are fed into the winding mechanism 2000 to be wound to form an electrode assembly wound body, since the positive electrode laminate portion 2312 formed after the positive electrode sheet 231 is cut off is located upstream of the positive electrode main body 2311 along the winding direction S, the positive electrode laminate portion 2312 will be fed into the winding mechanism 2000 for winding first, and the positive electrode main body 2311 will be wound later; that is, the positive electrode laminate portion 2312 can be wound inside the electrode assembly wound body.

[0120] Exemplarily, the positive electrode laminate portion 2312 can be wound to the innermost side, that is, the positive electrode laminate portion 2312 is at the center of the electrode assembly winding body (that is, between the first negative electrode straight portion 232a1 and the second negative electrode straight portion 232a2 formed by the negative electrode sheet 232); and / or, the positive electrode laminate portion 2312 can also be wound to any place inside the electrode assembly winding body, for example, the positive electrode laminate portion 2312 is located at any place inside the negative electrode sheet 232 (generally within the first five turns formed by the negative electrode sheet 232).

[0121] The negative electrode sheet 232 can form multiple negative straight portions 232a in the straight area 230a; that is, after the negative electrode sheet 232 is wound by the winding mechanism 2000 to form a winding structure with multiple turns and is pressed into a flat structure through a shaping operation, the multiple turns of the negative electrode sheet 232 form multiple straight negative straight portions 232a in the straight area 230a.

[0122] Among them, at least one positive electrode laminate portion 2312 is located between any two adjacent negative electrode straight portions 232a; illustratively, at least one positive electrode laminate portion 2312 can be wound between any negative electrode straight portion 232a and the adjacent negative electrode straight portion 232a, for example, between the first negative electrode straight portion 232a1 formed at the winding starting end of the negative electrode sheet 232 and the adjacent second negative electrode straight portion 232a2, or between the second negative electrode straight portion 232a2 and the fourth negative electrode straight portion 232a, etc.

[0123] It should be understood that the above-mentioned two adjacent negative straight portions 232a refer to two adjacent negative straight portions 232a in a direction perpendicular to the straight area 230a, and the positive electrode stacking portion 2312 can be arranged between the two adjacent negative straight portions 232a; in this way, the positive electrode active materials on the opposite sides of the positive electrode stacking portion 2312 can respectively react with the negative electrode active materials of the negative straight portion 232a on the corresponding side to form current.

[0124] The positive electrode laminate portion 2312 can be located only in the straight area 230a, that is, the positive electrode laminate portion 2312 is between any two adjacent negative electrode straight portions 232a and does not extend into the bending area 230b, and the first connecting member 234 located in the bending area 230b extends into the straight area 230a and connects to the positive electrode laminate portion 2312; or, at least one end of the positive electrode laminate portion 2312 extends into the bending area 230b, for example, one end of the positive electrode laminate portion 2312 extends into the bending area 230b and is connected to the first connecting member 234, or both opposite ends of the positive electrode laminate portion 2312 extend into the bending area 230b and are connected to the corresponding first connecting member 234.

[0125] With this arrangement, the positive electrode laminate portion 2312 can react with two adjacent negative electrode straight portions 232a to form current, and the first connecting member 234 can replace the positive electrode sheet 231 to bend in the bending area 230b, thereby effectively reducing the probability of the positive electrode sheet 231 being broken.

[0126] Please refer to Figure 4 、 Figure 5 and Figure 7 In some embodiments, at least one positive electrode laminate portion 2312 is located between a first negative electrode straight portion 232a1 and a second negative electrode straight portion 232a2 among the plurality of negative electrode straight portions 232a.

[0127] Among them, the first negative electrode straight portion 232a1 among the multiple negative electrode straight portions 232a refers to the first negative electrode straight portion 232a1 formed by the winding starting end of the negative electrode sheet 232 being wound at the innermost side by the winding mechanism 2000 and being shaped and pressed through the shaping operation; similarly, the second negative electrode straight portion 232a2 among the multiple negative electrode straight portions 232a refers to the second negative electrode straight portion 232a2 formed by the section of the negative electrode sheet 232 located downstream of the winding starting end being wound at the innermost side by the winding mechanism 2000 and being shaped and pressed through the shaping operation.

[0128] In this embodiment, by disposing at least one positive electrode laminate portion 2312 between the first negative electrode straight portion 232a1 and the second negative electrode straight portion 232a2 of the plurality of negative electrode straight portions 232a, the positive electrode active material coated on opposite sides of the positive electrode laminate portion 2312 can react with the first negative electrode straight portion 232a1 and the second negative electrode straight portion 232a2 in the electrolyte, generating a current. Compared to an electrode assembly 23 without a positive electrode laminate portion 2312 between the first negative electrode straight portion 232a1 and the second negative electrode straight portion 232a2, the electrode assembly 23 in this embodiment can effectively utilize the surface space on the opposing side of the first negative electrode straight portion 232a1 and the second negative electrode straight portion 232a2, thereby effectively improving the energy density of the electrode assembly 23.

[0129] At the same time, the positive electrode stacking part 2312 is connected to other positive electrode stacking parts 2312 or positive electrode main body parts 2311 through the first connecting member 234. The first connecting member 234 is located in the bending area 230b and is located in the innermost circle of the winding body, with the largest bending degree. In this way, it can replace the positive electrode sheet 231 for bending and effectively reduce the probability of brittle fracture of the positive electrode sheet 231; and it can also reduce the risk of decomposition of the positive electrode sheet 231 at the corner during use, which helps to improve the electrical performance of the electrode assembly 23.

[0130] Please refer to Figure 4 、 Figure 5 and Figure 8 In some embodiments, the step of cutting the positive electrode sheet 231 includes: In the winding direction S of the winding mechanism 2000 , the end portion of the positive electrode sheet 231 is cut to form a positive electrode main portion 2311 and at least one positive electrode laminate portion 2312 . The at least one positive electrode laminate portion 2312 is located downstream of the positive electrode main portion 2311 .

[0131] Among them, in the winding direction S of the winding mechanism 2000, the last section of the positive electrode sheet 231 refers to the downstream part of the positive electrode sheet 231 along the winding direction S; it should be understood that when the positive electrode sheet 231 is fed into the winding mechanism 2000 for winding, the last section of the positive electrode sheet 231 in the winding direction S is finally fed into the winding mechanism 2000.

[0132] In this embodiment, the positive electrode sheet 231 is cut at its end in the winding direction S, so that the positive electrode sheet 231 forms a positive electrode main portion 2311 and at least one positive electrode laminate portion 2312. It should be understood that because the cut is located at the end of the positive electrode sheet 231 in the winding direction S, the shorter portion of the positive electrode sheet 231 formed after the cut is located downstream of the longer portion, that is, the positive electrode laminate portion 2312 is located downstream of the positive electrode main portion 2311.

[0133] After the electrode assembly 23 is formed, any positive electrode lamination portion 2312 is located only in one circle of the electrode assembly 23, such as the outermost circle. Optionally, the number of positive electrode lamination portions 2312 can be one, two, or more than two; one or more positive electrode lamination portions 2312 are formed downstream of the positive electrode main body portion 2311 along the winding direction S.

[0134] Illustratively, in some embodiments, when a cutting operation is performed on the last section of the positive electrode sheet 231 in the winding direction S, the positive electrode sheet 231 will form a positive electrode main body 2311 and a positive electrode laminate portion 2312 located downstream of the positive electrode main body 2311; the first connecting member 234 is covered on the incision formed by the cutting operation, so that the first connecting member 234 simultaneously connects the positive electrode main body 2311 and the positive electrode laminate portion 2312 and connects them into one body, so as to facilitate subsequent transmission operations and winding operations.

[0135] When the last section of the positive electrode sheet 231 in the winding direction S is cut twice, the positive electrode sheet 231 will form a positive electrode main body 2311 and two positive electrode laminate parts 2312 located downstream of the positive electrode main body 2311; the two incisions formed by the two cutting operations are respectively covered with first connecting members 234, so that one first connecting member 234 connects the positive electrode main body 2311 and the positive electrode laminate part 2312 at the same time, and the other first connecting member 234 connects the two positive electrode laminate parts 2312 at the same time, so that the positive electrode main body 2311 and the two positive electrode laminate parts 2312 are connected to form a whole, so as to facilitate subsequent transmission operations and winding operations.

[0136] By analogy, when the last section of the positive electrode sheet 231 in the winding direction S is cut m times, the positive electrode sheet 231 will form a positive electrode main body 2311 and m positive electrode laminate parts 2312 located downstream of the positive electrode main body 2311, where m is a positive integer not less than 2; and the m incisions formed after the m cutting operations are respectively covered with the first connecting member 234, so that the positive electrode main body 2311 and the m positive electrode laminate parts 2312 are connected to form a whole.

[0137] It should be understood that when there are multiple positive electrode lamination parts 2312 , the multiple positive electrode lamination parts 2312 can be arranged in sequence and spaced apart in a direction perpendicular to the straight portion.

[0138] In this way, by operating the downstream end section of the positive electrode sheet 231 along the winding direction S, at least one positive electrode laminate portion 2312 formed by cutting is located downstream of the positive electrode main body 2311 along the winding direction S of the winding mechanism 2000, so that at least one positive electrode laminate portion 2312 can be wound to the outermost side of the electrode assembly winding body, so that the first connecting member 234 connecting the positive electrode laminate portion 2312 and the positive electrode main body 2311 will also be located at the outermost side of the electrode assembly winding body; when the electrode assembly winding body is shaped, the first connecting member 234 can replace the positive electrode sheet 231 to be bent in the electrode assembly winding body, which can effectively reduce the probability of brittle fracture of the positive electrode sheet 231.

[0139] It should be understood that in some embodiments, the first section and the last section of the positive electrode sheet 231 in the winding direction S can be cut at the same time, so that the positive electrode main body 2311 is provided with a positive electrode laminate portion 2312 upstream and downstream along the winding direction S, such as Figure 6 shown.

[0140] Please refer to Figure 4 、 Figure 5 and Figure 8 In some embodiments, the step of shaping the electrode assembly wound body to obtain the electrode assembly 23 with a flat structure includes: The negative electrode sheet 232 includes n negative straight portions 232a formed in the straight area 230a; at least one positive electrode laminate portion 2312 is located between two adjacent negative straight portions 232a; and / or, at least one positive electrode laminate portion 2312 is wound to the outside of at least one of the nth negative straight portion 232a and the n-1th negative straight portion 232a of the n negative straight portions 232a.

[0141] The aforementioned n negative straight portions 232 a refer to all negative straight portions 232 a formed in the straight region 230 a of the negative electrode sheet 232 ; wherein n is an integer greater than 1.

[0142] The nth negative straight portion 232a mentioned above refers to the last negative straight portion 232a among the n negative straight portions 232a formed by the negative electrode sheet 232, that is, a negative straight portion 232a formed by the last winding section of the negative electrode sheet 232 (that is, the end that last enters the winding mechanism 2000 for the winding operation).

[0143] The aforementioned n−1th negative electrode straight portion 232 a refers to the penultimate negative electrode straight portion 232 a 2 among the n negative electrode straight portions 232 a formed by the negative electrode sheet 232 .

[0144] It should be understood that after winding to form the electrode assembly winding body and forming a flat electrode assembly 23 through a shaping operation, the nth negative electrode straight portion 232a and the n-1th negative electrode straight portion 232a should be the outermost parts of the negative electrode sheet 232 on the opposite sides in the direction perpendicular to the straight area 230a.

[0145] Illustratively, in some embodiments, the positive electrode laminate portion 2312 may be wound to the outward side of the n-th negative electrode straight portion 232a among the n negative electrode straight portions 232a; and / or, the positive electrode laminate portion 2312 may be wound to the outward side of the n-1-th negative electrode straight portion 232a among the n negative electrode straight portions 232a; and / or, the positive electrode laminate portion 2312 may be wound to the inward side of the n-th negative electrode straight portion 232a among the n negative electrode straight portions 232a, and / or, the positive electrode laminate portion 2312 may be wound to the inward side of the n-1-th negative electrode straight portion 232a among the n negative electrode straight portions 232a, etc.

[0146] In this way, at least one positive electrode laminate portion 2312 can be wound to the outside of the electrode assembly winding body, for example, the outside of at least one of the nth negative electrode straight portion 232a and the n-1th negative electrode straight portion 232a of the n negative electrode straight portions 232a, so that the positive electrode laminate can be used in pair with the outermost negative electrode sheet 232 of other electrode assemblies 23; and / or, at least one positive electrode laminate portion 2312 can be wound between two adjacent negative electrode straight portions 232a, and the positive electrode laminate and the two adjacent negative electrode straight portions 232a are used to react to form current, and the first connecting portion can be located in the bending area 230b for bending and deformation to reduce the probability of the positive electrode sheet 231 breaking in the bending area 230b.

[0147] Please refer to Figures 5 to 9 In some embodiments, before the step of feeding the separator 233 , the negative electrode sheet 232 and the positive electrode sheet 231 into the winding mechanism 2000 to form an electrode assembly winding body, the following steps are further included: S300a, feeding the positive electrode sheet 231 into the first buffer mechanism 3000, which caches the positive electrode sheet 231 of a preset length; the first buffer mechanism 3000 is configured to maintain the rate at which the positive electrode sheet 231 is fed into the winding mechanism 2000 by releasing the cached positive electrode sheet 231.

[0148] Among them, the first buffer mechanism 3000 refers to a mechanism for caching a preset length of the positive electrode sheet 231, and can release the cached positive electrode sheet 231 to meet the requirement that the positive electrode sheet 231 does not stop winding during the cutting operation or the covering operation of the first connecting member 234.

[0149] Exemplarily, in some embodiments, the first buffer mechanism 3000 may include multiple adjustment rollers, and the multiple adjustment rollers can be moved and adjusted in the height direction; when the positive electrode sheet 231 is cut and the first connecting member 234 is covered at the cut position, the positive electrode sheet 231 reconnected to form a whole through the first connecting member 234 will be transferred to the first buffer mechanism 3000 and pass through the multiple adjustment rollers in turn, and adjusted up and down in the height direction by the multiple adjustment rollers to achieve caching of the positive electrode sheet 231 in the first buffer mechanism 3000, or releasing the positive electrode sheet 231 outward from the first buffer mechanism 3000.

[0150] For example, when the number of adjustment rollers is five, the first, third and fifth adjustment rollers along the transmission direction of the positive electrode sheet 231 can be fixed at a preset height, and the second and fourth adjustment rollers can be moved and adjusted in the height direction. The positive electrode sheet 231 passes through the bottom of the first adjustment roller, the top of the second adjustment roller, the bottom of the third adjustment roller, the top of the fourth adjustment roller and the bottom of the fifth adjustment roller in sequence, and by raising the second and fourth adjustment rollers, the length of the positive electrode sheet 231 cached between the five adjustment rollers is increased; when the positive electrode sheet 231 needs to be released, the height of at least one of the second adjustment roller and the fourth adjustment roller is lowered, and the length of the positive electrode sheet 231 cached between the five adjustment rollers is reduced, and the cached positive electrode sheet 231 is released from the first buffer mechanism 3000 and supplied to the winding mechanism 2000 for winding operation.

[0151] It should be understood that in step S200 , when the positive electrode sheet 231 is cut off, the positive electrode sheet 231 needs to stop being transported, and the positive electrode sheet 231 in the stopped state needs to be cut off.

[0152] Likewise, in step S300 , when the first connecting member 234 is covered on the corresponding cut portion of the positive electrode sheet 231 , it is also necessary to stop transporting the positive electrode sheet 231 .

[0153] Therefore, to reduce the impact of the above steps on the feeding of the separator 233, the negative electrode sheet 232, and the positive electrode sheet 231 into the winding mechanism 2000 to form the electrode assembly wound body in step S400, a preset length of positive electrode sheet 231 can be buffered in the first buffer mechanism 3000. When step S200 is performed, the previous transport operation of the first buffer mechanism 3000 can be stopped to perform the cutting operation, and the first buffer mechanism 3000 can release the buffered positive electrode sheet 231, so that the positive electrode sheet 231 can be continuously fed into the winding mechanism 2000 for the winding operation. Similarly, when step S300 is performed, the previous transport operation of the first buffer mechanism 3000 can be stopped to perform the covering operation of the first connector 234, and the first buffer mechanism 3000 can release the buffered positive electrode sheet 231, so that the positive electrode sheet 231 can be continuously fed into the winding mechanism 2000 for the winding operation.

[0154] In this configuration, the first buffer mechanism 3000 can maintain the rate at which the positive electrode sheet 231 is fed into the winding mechanism 2000 by releasing the internally cached positive electrode sheet 231, thereby reducing the impact on the transmission speed of the positive electrode sheet 231 during the cutting operation of the positive electrode sheet 231 or the covering operation of the first connecting member 234, thereby effectively improving the production rate of the electrode assembly 23.

[0155] Please refer to Figures 10 to 14 In some embodiments, before the step of feeding the separator 233 , the negative electrode sheet 232 and the positive electrode sheet 231 into the winding mechanism 2000 to form an electrode assembly winding body, the following steps are further included: S310, cutting the negative electrode sheet 232; S320, providing a soft second connecting member 235, covering the corresponding cut portion of the negative electrode sheet 232, and connecting the second connecting member 235 with the cut negative electrode sheet 232 to form a whole; The step of shaping the electrode assembly wound body to obtain a flat electrode assembly 23 includes: At least a portion of the second connecting member 235 is located in the bending region 230 b.

[0156] In step S310 , the negative electrode sheet 232 is cut off. Optionally, the negative electrode sheet 232 may be cut off once, or may be cut off twice or more times.

[0157] In step S320, the second connecting member 235 is a flexible connecting structure; optionally, the second connecting member 235 can be, but is not limited to, adhesive tape, an insulating film layer, etc. It should be understood that the flexible second connecting member 235 does not risk breaking when bent at a large angle.

[0158] The second connecting member 235 is covered on the corresponding cut portion of the negative electrode plate 232, that is, the second connecting member 235 can be set at the corresponding cut portion and simultaneously connected to the two parts formed after cutting; in this way, the second connecting member 235 can cover the incisions of the two parts formed by cutting, so that the second connecting member 235 can cover the burrs generated at the incisions formed by cutting, thereby effectively reducing the risk of puncture of the isolation membrane 233 by the burrs at the incisions.

[0159] At the same time, the second connecting member 235 can also reconnect the two parts formed after cutting to form a whole. During the transmission and winding process, the structure connected to form a whole is less likely to have risks such as falling off and loosening; this can effectively improve the quality of the produced electrode assembly 23.

[0160] At least a portion of the second connector 235 is located in the bending region 230 b . Thus, the second connector 235 can replace the negative electrode sheet 232 in the bending region 230 b , and the second connector 235 replaces the negative electrode sheet 232 in bending and deformation.

[0161] Optionally, the second connector 235 can be completely located in the bending zone 230b, and a portion of the negative electrode plate 232 extends into the bending zone 230b or extends to the junction of the bending zone 230b and the straight zone 230a and is connected to the second connector 235; or, a portion of the second connector 235 can be located in the bending zone 230b, and at least one end of the second connector 235 extends into the straight zone 230a and is connected to the negative electrode plate 232.

[0162] For example, in some embodiments, taking the second connecting member 235 as adhesive tape, in a flat electrode assembly 23, the adhesive tape can be located in the bending area 230b, and the opposite ends of the adhesive tape are respectively located at the junction of the bending area 230b and the straight area 230a and adhered to the corresponding parts of the cut negative electrode plate 232; when the adhesive tape is bent and deformed at a large angle in the bending area 230b, due to the soft nature of the adhesive tape itself, the adhesive tape will not break and there will be no risk of puncturing the isolation membrane 233.

[0163] Optionally, a second connector 235 may be provided on either side of the negative electrode sheet 232 in the thickness direction and cover the cut portion; or, a second connector 235 may be provided on both opposite sides of the negative electrode sheet 232 in the thickness direction and cover the cut portion.

[0164] With such a configuration, the negative electrode sheet 232 can be cut and then covered with the second connecting member 235 at the corresponding cut portion and connected to form a whole, so that when the electrode assembly 23 is formed, at least part of the second connecting member 235 is located in the bending area 230b; in this way, the second connecting member 235 can replace the negative electrode sheet 232 to be bent in the bending area 230b, thereby effectively reducing the probability of brittle fracture of the negative electrode sheet 232.

[0165] Please refer to Figures 10 to 14 In some embodiments, the step of cutting the negative electrode sheet 232 includes: In the winding direction S of the winding mechanism 2000 , the first section of the negative electrode sheet 232 is cut to form a negative electrode main body 2321 and at least one negative electrode laminate 2322 . The at least one negative electrode laminate 2322 is located upstream of the negative electrode main body 2321 .

[0166] Among them, in the winding direction S of the winding mechanism 2000, the first section of the negative electrode sheet 232 refers to the upstream part of the negative electrode sheet 232 along the winding direction S; it should be understood that when the negative electrode sheet 232 is fed into the winding mechanism 2000 for winding, the first section of the negative electrode sheet 232 in the winding direction S is first fed into the winding mechanism 2000.

[0167] In this embodiment, the first section of the negative electrode sheet 232 in the winding direction S is cut, so that the negative electrode sheet 232 forms a negative electrode main portion 2321 and at least one negative electrode laminate portion 2322. It should be understood that because the cut is located at the first section of the negative electrode sheet 232 in the winding direction S, the shorter portion of the negative electrode sheet 232 formed after the cut will be located upstream of the longer portion, that is, the negative electrode laminate portion 2322 is located upstream of the negative electrode main portion 2321.

[0168] The negative electrode main body 2321 refers to the longer portion of the negative electrode sheet 232 after being cut. The negative electrode main body 2321 can be wound by the winding mechanism 2000 to form a winding structure with multiple turns.

[0169] Correspondingly, the negative electrode lamination portion 2322 refers to the shorter portion of the negative electrode sheet 232 after it is cut. After the electrode assembly 23 is formed, any negative electrode lamination portion 2322 is located only in one coil of the electrode assembly 23, such as the innermost coil, the middle coil, or any other position. Optionally, the number of negative electrode lamination portions 2322 can be one, two, or more than two; one or more negative electrode lamination portions 2322 are formed upstream of the negative electrode main body 2321 along the winding direction S.

[0170] Illustratively, in some embodiments, when a cutting operation is performed on the first section of the negative electrode sheet 232 in the winding direction S, the negative electrode sheet 232 will form a negative electrode main body 2321 and a negative electrode laminate portion 2322 located upstream of the negative electrode main body 2321; a second connecting member 235 is covered on the incision formed by the cutting operation, so that the second connecting member 235 simultaneously connects the negative electrode main body 2321 and the negative electrode laminate portion 2322 and connects them into one body, so as to facilitate subsequent transmission operations and winding operations.

[0171] When the first section of the negative electrode sheet 232 in the winding direction S is cut twice, the negative electrode sheet 232 will form a negative electrode main body 2321 and two negative electrode laminate parts 2322 located upstream of the negative electrode main body 2321; the two incisions formed by the two cutting operations are respectively covered with second connecting members 235, so that one second connecting member 235 connects the negative electrode main body 2321 and the negative electrode laminate part 2322 at the same time, and the other second connecting member 235 connects the two negative electrode laminate parts 2322 at the same time, so that the negative electrode main body 2321 and the two negative electrode laminate parts 2322 are connected to form a whole, so as to facilitate subsequent transmission operations and winding operations.

[0172] By analogy, when the first section of the negative electrode sheet 232 in the winding direction S is cut m times, the negative electrode sheet 232 will form a negative electrode main body 2321 and m negative electrode laminate parts 2322 located upstream of the negative electrode main body 2321, where m is a positive integer not less than 2; and, the m incisions formed after the m cutting operations are respectively covered with a second connecting member 235, so that the negative electrode main body 2321 and the m negative electrode laminate parts 2322 are connected to form a whole.

[0173] It should be understood that when there are multiple negative electrode lamination parts 2322 , the multiple negative electrode lamination parts 2322 may be sequentially arranged at intervals along a direction perpendicular to the straight portion.

[0174] In this way, at least one negative electrode laminate portion 2322 is arranged upstream of the negative electrode main body portion 2321 along the winding direction S of the winding mechanism 2000, so that at least one negative electrode laminate portion 2322 can be wound into the interior of the electrode assembly winding body, so that the second connecting member 235 connecting the negative electrode laminate portion 2322 and the negative electrode main body portion 2321 will also be located inside the electrode assembly winding body; when the electrode assembly winding body is shaped, the second connecting member 235 can replace the negative electrode sheet 232 for bending inside the electrode assembly winding body, which can effectively reduce the probability of brittle fracture of the negative electrode sheet 232.

[0175] Please refer to Figures 10 to 14In some embodiments, the step of shaping the electrode assembly wound body to obtain the electrode assembly 23 with a flat structure includes: The negative electrode main body 2321 includes multiple negative electrode straight portions 232a formed in the straight area 230a, at least one negative electrode laminate portion 2322 and at least two positive electrode laminate portions 2312 are located between the first negative electrode straight portion 232a1 and the second negative electrode straight portion 232a2 in the multiple negative electrode straight portions 232a, and positive electrode laminate portions 2312 are provided on opposite sides of any negative electrode laminate portion 2322.

[0176] In this embodiment, by arranging at least one negative electrode laminate portion 2322 between the first negative electrode straight portion 232a1 and the second negative electrode straight portion 232a2 among the multiple negative electrode straight portions 232a; at the same time, at least two positive electrode laminate portions 2312 can be synchronously arranged between the first negative electrode straight portion 232a1 and the second negative electrode straight portion 232a2 among the multiple negative electrode straight portions 232a, so that at least one negative electrode laminate portion 2322 and at least two positive electrode laminate portions 2312 are in an alternating stacking state, and the opposite sides of the negative electrode laminate portion 2322 are both positive electrode laminate portions 2312; in this way, it can be effectively ensured that the opposite ends of each positive electrode laminate portion 2312 and each negative electrode laminate portion 2322 can react to form current, so as to ensure the energy density of the electrode assembly 23.

[0177] At the same time, in the center of the electrode assembly 23, a first connector 234 is used instead of the positive electrode sheet 231 to be arranged in the bending area 230b, and a second connector 235 is used instead of the negative electrode sheet 232 to be arranged in the bending area 230b. When the soft first connector 234 and the soft second connector 235 are bent and deformed at a large angle, there is no risk of breakage, nor is there any risk of puncturing the isolation membrane 233. Moreover, since the positive electrode sheet 231 does not need to be bent at a large angle in the innermost circle of the bending area 230b, the probability of the positive electrode sheet 231 having insufficient CB value in the bending area 230b and lithium deposition is lower.

[0178] Please refer to Figures 10 to 14 In some embodiments, the step of cutting the negative electrode sheet 232 includes: In the winding direction S of the winding mechanism 2000 , the end portion of the negative electrode sheet 232 is cut to form a negative electrode main portion 2321 and at least one negative electrode laminate portion 2322 . The at least one negative electrode laminate portion 2322 is located downstream of the negative electrode main portion 2321 .

[0179] Among them, in the winding direction S of the winding mechanism 2000, the last section of the negative electrode sheet 232 refers to the downstream part of the negative electrode sheet 232 along the winding direction S; it should be understood that when the negative electrode sheet 232 is fed into the winding mechanism 2000 for winding, the last section of the negative electrode sheet 232 in the winding direction S is finally fed into the winding mechanism 2000.

[0180] In this embodiment, the negative electrode sheet 232 is cut at its end in the winding direction S, so that the negative electrode sheet 232 forms a negative electrode main body 2321 and at least one negative electrode laminate 2322. It should be understood that because the cut is located at the end of the negative electrode sheet 232 in the winding direction S, the shorter portion of the negative electrode sheet 232 formed after the cut is located downstream of the longer portion, that is, the negative electrode laminate 2322 is located downstream of the negative electrode main body 2321.

[0181] After the electrode assembly 23 is formed, any negative electrode lamination portion 2322 is located only in one circle of the electrode assembly 23, such as the outermost circle. Optionally, the number of negative electrode lamination portions 2322 can be one, two, or more than two; one or more negative electrode lamination portions 2322 are formed downstream of the negative electrode main body 2321 along the winding direction S.

[0182] Illustratively, in some embodiments, when a cutting operation is performed on the last section of the negative electrode sheet 232 in the winding direction S, the negative electrode sheet 232 will form a negative electrode main body 2321 and a negative electrode laminate portion 2322 located downstream of the negative electrode main body 2321; a second connecting member 235 is covered on the incision formed by the cutting operation, so that the second connecting member 235 simultaneously connects the negative electrode main body 2321 and the negative electrode laminate portion 2322 and connects them into one body, so as to facilitate subsequent transmission operations and winding operations.

[0183] When the last section of the negative electrode sheet 232 in the winding direction S is cut twice, the negative electrode sheet 232 will form a negative electrode main body 2321 and two negative electrode laminate parts 2322 located downstream of the negative electrode main body 2321; the two incisions formed by the two cutting operations are respectively covered with second connecting members 235, so that one second connecting member 235 simultaneously connects the negative electrode main body 2321 and the negative electrode laminate part 2322, and the other second connecting member 235 simultaneously connects the two negative electrode laminate parts 2322, so that the negative electrode main body 2321 and the two negative electrode laminate parts 2322 are connected to form a whole, so as to facilitate subsequent transmission operations and winding operations.

[0184] By analogy, when the last section of the negative electrode sheet 232 in the winding direction S is cut m times, the negative electrode sheet 232 will form a negative electrode main body 2321 and m negative electrode laminate parts 2322 located downstream of the negative electrode main body 2321, where m is a positive integer not less than 2; and, the m incisions formed after the m cutting operations are respectively covered with a second connecting member 235, so that the negative electrode main body 2321 and the m negative electrode laminate parts 2322 are connected to form a whole.

[0185] It should be understood that when there are multiple negative electrode lamination parts 2322 , the multiple negative electrode lamination parts 2322 may be sequentially arranged at intervals along a direction perpendicular to the straight portion.

[0186] In this way, by operating the downstream end section of the negative electrode sheet 232 along the winding direction S, at least one negative electrode laminate portion 2322 formed by cutting is located downstream of the negative electrode main body 2321 along the winding direction S of the winding mechanism 2000, so that at least one negative electrode laminate portion 2322 can be wound to the outermost side of the electrode assembly winding body, so that the second connecting member 235 connecting the negative electrode laminate portion 2322 and the negative electrode main body 2321 will also be located at the outermost side of the electrode assembly winding body; when the electrode assembly winding body is shaped, the second connecting member 235 can replace the negative electrode sheet 232 for bending in the electrode assembly winding body, which can effectively reduce the probability of brittle fracture of the negative electrode sheet 232.

[0187] It should be understood that in some embodiments, the first section and the last section of the negative electrode sheet 232 in the winding direction S can be cut at the same time, so that the negative electrode main body 2321 is provided with a negative electrode laminate portion 2322 upstream and downstream along the winding direction S, as shown in FIG. Figure 12 shown.

[0188] Please refer to Figures 10 to 14 In some embodiments, the step of shaping the electrode assembly wound body to obtain the electrode assembly 23 with a flat structure includes: The negative electrode main body 2321 includes n negative electrode straight portions 232a formed in the straight area 230a; at least one positive electrode laminate portion 2312 and at least one negative electrode laminate portion 2322 are located outside at least one of the nth negative electrode straight portion 232a and the n-1th negative electrode straight portion 232a of the n negative electrode straight portions 232a.

[0189] In this embodiment, at least one positive electrode laminate portion 2312 and at least one negative electrode laminate portion 2322 can be wound to the outer ring of the electrode assembly winding body, for example, on the outward side of the n-th negative electrode straight portion 232a among the n negative electrode straight portions 232a, or on the outward side of the n-1-th negative electrode straight portion 232a among the n negative electrode straight portions 232a.

[0190] For example, in some embodiments, at least one positive electrode laminate portion 2312 and at least one negative electrode laminate portion 2322 can be wound to the outward side of the n-th negative electrode straight portion 232a among the n negative electrode straight portions 232a, and the positive electrode laminate portion 2312 is adjacent to the n-th negative electrode straight portion 232a, and the positive electrode laminate portion 2312 or the negative electrode laminate portion 2322 is located at the outermost side facing away from the n-th negative electrode straight portion 232a.

[0191] And / or, at least one positive electrode laminate portion 2312 and at least one negative electrode laminate portion 2322 can be wound to the outward side of the n-1th negative electrode straight portion 232a among the n negative electrode straight portions 232a; similarly, the positive electrode laminate portion 2312 is adjacent to the nth negative electrode straight portion 232a, and the positive electrode laminate portion 2312 or the negative electrode laminate portion 2322 is located at the outermost side facing away from the nth negative electrode straight portion 232a.

[0192] In this way, at least one positive electrode laminate portion 2312 and at least one negative electrode laminate portion 2322 can be wound to the outside of the electrode assembly winding body, for example, the outside of at least one of the nth negative electrode straight portion 232a and the n-1th negative electrode straight portion 232a of n negative electrode straight portions 232a, and the positive electrode laminate portion 2312 can be connected to the positive electrode main body 2311 through the first connecting member 234, and the negative electrode laminate portion 2322 can be connected to the negative electrode main body 2321 through the second connecting member 235, and the risk of breakage of the positive electrode sheet 231 and the negative electrode sheet 232 is lower.

[0193] Please refer to Figures 11 to 15 In some embodiments, before the step of feeding the separator 233 , the negative electrode sheet 232 and the positive electrode sheet 231 into the winding mechanism 2000 to form an electrode assembly winding body, the step further includes: S330 , feeding the negative electrode sheet 232 into the second buffer mechanism 4000 , which buffers the negative electrode sheet 232 of a preset length; the second buffer mechanism 4000 is configured to maintain the rate at which the negative electrode sheet 232 is fed into the winding mechanism 2000 by releasing the negative electrode sheet 232 buffered therein.

[0194] The second buffer mechanism 4000 is used to buffer the negative electrode sheet 232 of a preset length and can release the buffered negative electrode sheet 232 to meet the requirement that the negative electrode sheet 232 does not stop winding during the cutting operation or the covering operation of the second connecting member 235 .

[0195] Exemplarily, in some embodiments, the second buffer mechanism 4000 may include multiple adjustment rollers, and the multiple adjustment rollers can be moved and adjusted in the height direction; after the negative electrode sheet 232 is cut and the second connecting member 235 is covered at the cut position, the negative electrode sheet 232 that is reconnected to form a whole through the second connecting member 235 will be transferred to the second buffer mechanism 4000 and pass through the multiple adjustment rollers in turn, and the multiple adjustment rollers will adjust it up and down in the height direction to achieve caching of the negative electrode sheet 232 in the second buffer mechanism 4000, or release of the positive electrode sheet 231 from the second buffer mechanism 4000.

[0196] For example, when the number of adjustment rollers is five, the first, third and fifth adjustment rollers along the transmission direction of the negative electrode sheet 232 can be fixed at a preset height, and the second and fourth adjustment rollers can be moved and adjusted in the height direction. The negative electrode sheet 232 passes through the bottom of the first adjustment roller, the top of the second adjustment roller, the bottom of the third adjustment roller, the top of the fourth adjustment roller and the bottom of the fifth adjustment roller in sequence, and by raising the second and fourth adjustment rollers, the length of the negative electrode sheet 232 cached between the five adjustment rollers is increased; when the negative electrode sheet 232 needs to be released, the height of at least one of the second adjustment roller and the fourth adjustment roller is lowered, and the length of the negative electrode sheet 232 cached between the five adjustment rollers is reduced, and the cached negative electrode sheet 232 is released from the second buffer mechanism 4000 and supplied to the winding mechanism 2000 for winding operation.

[0197] It should be understood that in step S310 , when the negative electrode sheet 232 is cut off, the negative electrode sheet 232 needs to stop being transported, and the cut-off operation is performed on the negative electrode sheet 232 in the stopped state.

[0198] Likewise, in step S320 , when the second connecting member 235 is covered on the corresponding cut portion of the negative electrode sheet 232 , it is also necessary to stop transporting the negative electrode sheet 232 .

[0199] Therefore, to reduce the impact of the above steps on the feeding of the separator 233, the negative electrode sheet 232, and the positive electrode sheet 231 into the winding mechanism 2000 to form the electrode assembly wound body in step S400, a predetermined length of negative electrode sheet 232 can be buffered in the second buffer mechanism 4000. When step S310 is performed, the previous transport operation of the second buffer mechanism 4000 can be stopped to perform the cutting operation, and the second buffer mechanism 4000 can release the buffered negative electrode sheet 232, so that the negative electrode sheet 232 can be continuously fed into the winding mechanism 2000 for the winding operation. Similarly, when step S320 is performed, the previous transport operation of the second buffer mechanism 4000 can be stopped to perform the covering operation of the second connector 235, and the second buffer mechanism 4000 can release the buffered negative electrode sheet 232, so that the negative electrode sheet 232 can be continuously fed into the winding mechanism 2000 for the winding operation.

[0200] In this configuration, the second buffer mechanism 4000 can maintain the rate at which the negative electrode sheet 232 is fed into the winding mechanism 2000 by releasing the internally cached negative electrode sheet 232, so as to reduce the impact on the transmission speed of the negative electrode sheet 232 during the cutting operation of the negative electrode sheet 232 or the covering operation of the second connecting member 235, thereby effectively improving the production rate of the electrode assembly 23.

[0201] Please refer to Figure 11 and Figure 16 In some embodiments, the winding direction S of the winding mechanism 2000 is clockwise; alternatively, the winding direction S of the winding mechanism 2000 is counterclockwise.

[0202] By adopting the above technical solution, the winding direction S of the winding mechanism 2000 can be set to a clockwise direction or a counterclockwise direction to obtain a corresponding electrode assembly winding body.

[0203] It should be understood that the winding direction S of the winding mechanism 2000 refers to the direction in which the winding needle of the winding mechanism 2000 fixes and connects the separator 233, the positive electrode sheet 231 and the negative electrode sheet 232 and drives them to rotate.

[0204] In this embodiment, the clockwise direction and the counterclockwise direction refer to the rotation direction of the winding needle of the winding mechanism 2000 observed by the operator when the operator is directly in front of the winding mechanism 2000 and facing the winding mechanism 2000.

[0205] When the winding direction S of the winding mechanism 2000 is clockwise, the winding needle of the winding mechanism 2000 can drive the isolation film 233, the positive electrode sheet 231 and the negative electrode sheet 232 to be wound in the clockwise direction to form an electrode assembly wound body; when the winding direction S of the winding mechanism 2000 is counterclockwise, the winding needle of the winding mechanism 2000 can drive the isolation film 233, the positive electrode sheet 231 and the negative electrode sheet 232 to be wound in the counterclockwise direction to form an electrode assembly wound body.

[0206] In this manner, the winding direction S of the winding mechanism 2000 can be set to a clockwise direction or a counterclockwise direction to obtain a corresponding electrode assembly wound body.

[0207] Please refer to Figures 17 to 19 In some embodiments, the isolation membrane 233 includes a first membrane 2331 and a second membrane 2332 ; The step of feeding the separator 233, the negative electrode sheet 232 and the positive electrode sheet 231 into the winding mechanism 2000 for winding to form an electrode assembly wound body includes: S410, disposing the negative electrode plate 232 on the top side of the first separator 2331, disposing the second separator 2332 on the top side of the negative electrode plate 232, and disposing the positive electrode plate 231 on the top side of the second separator 2332; S420 , feeding the first separator 2331 , the second separator 2332 , the positive electrode sheet 231 and the negative electrode sheet 232 into the winding mechanism 2000 for winding to form an electrode assembly winding body.

[0208] Among them, the isolation membrane 233 includes a first membrane 2331 and a second membrane 2332. The first membrane 2331 and the second membrane 2332 can be used to separate the positive electrode plate 231 and the negative electrode plate 232 respectively, so that the positive electrode plate 231 and the negative electrode plate 232 will not be short-circuited after winding; and the first membrane 2331 and the second membrane 2332 can provide for the transfer and reaction of positive ions and negative ions.

[0209] Optionally, the first diaphragm 2331 and the second diaphragm 2332 may be fed separately, for example, by performing unwinding and feeding operations on the first diaphragm 2331 and the second diaphragm 2332 respectively through an unwinding mechanism.

[0210] In step S410, the positive electrode sheet 231, the second separator 2332, the negative electrode sheet 232 and the first separator 2331 can be stacked in sequence from the top side to the bottom side, that is, the positive electrode sheet 231 is located at the top side, the second separator 2332 is used to separate the positive electrode sheet 231 and the negative electrode sheet 232, and the negative electrode sheet 232 is located between the second separator 2332 and the first separator 2331.

[0211] Among them, the above-mentioned negative electrode plate 232 is set on the top side of the first diaphragm 2331, which means that during the horizontal transmission of the negative electrode plate 232 and the first diaphragm 2331, the negative electrode plate 232 is located above the first diaphragm 2331 in the direction of gravity; similarly, the above-mentioned setting of the second diaphragm 2332 on the top side of the negative electrode plate 232 means that during the horizontal transmission of the second diaphragm 2332 and the negative electrode plate 232, the second diaphragm 2332 is located above the negative electrode plate 232 in the direction of gravity; the above-mentioned setting of the positive electrode plate 231 on the top side of the second diaphragm 2332 means that during the horizontal transmission of the second diaphragm 2332 and the positive electrode plate 231, the positive electrode plate 231 is located above the second diaphragm 2332 in the direction of gravity.

[0212] In this way, during the winding process of the winding mechanism 2000, the positive electrode sheet 231, the second separator 2332, the negative electrode sheet 232 and the first separator 2331 can be wound in a stacked manner from the top side to the bottom side to obtain the corresponding electrode assembly winding body.

[0213] Please refer to Figures 19 to 21 In some embodiments, the first separator 2331 , the second separator 2332 , the positive electrode sheet 231 , and the negative electrode sheet 232 are fed into the winding mechanism 2000 and wound to form an electrode assembly wound body, including: S421, rolling and combining the negative electrode sheet 232 and the first separator 2331 to form a first wound material 236; S422, rolling and combining the positive electrode sheet 231 and the second separator 2332 to form a second wound material 237; S423 , feeding the first winding material 236 and the second winding material 237 into the winding mechanism 2000 and winding them to form an electrode assembly winding body.

[0214] In step S421, the negative electrode sheet 232 and the first separator 2331 can be rolled and laminated to form a first wound material 236. It should be understood that since the cut negative electrode sheet 232 is connected to form a whole by the second connector 235, the integrated negative electrode sheet 232 and the first separator 2331 are more effectively laminated during the roll-combination operation, and the probability of partial detachment of the negative electrode sheet 232 is lower.

[0215] In step S422, the positive electrode sheet 231 and the second separator 2332 can be rolled and laminated to form a first wound material 236. It should be understood that since the cut positive electrode sheet 231 is connected to form a whole by the first connector 234, the composite effect of the integrated positive electrode sheet 231 and the second separator 2332 is better during the roll-combination, and the probability of partial detachment of the positive electrode sheet 231 is lower.

[0216] It can be understood that the order of step S421 and step S422 can be interchanged; or, step S421 and step S422 can be performed simultaneously.

[0217] In step S423, the first and second winding materials 236, 237, respectively obtained by roll-combining, can be fed into the winding mechanism 2000 and wound to form an electrode assembly wound body. Alternatively, the first and second winding materials 236, 237 can be fed into the winding mechanism 2000 independently; or, the first and second winding materials 236, 237 can be rolled again and then fed into the winding mechanism 2000 for winding.

[0218] With such an arrangement, the negative electrode sheet 232 and the first separator 2331 can be rolled and compounded to form the first wound material 236, and the positive electrode sheet 231 and the second separator 2332 can be rolled and compounded to form the second wound material 237, and then the first wound material 236 and the second wound material 237 can be fed into the winding mechanism 2000 and wound to form an electrode assembly wound body, so as to improve the compactness of the electrode assembly wound body; wherein, after the positive electrode sheet 231 is cut, it is connected to form a whole through the first connecting member 234, and after the negative electrode sheet 232 is cut, it is connected to form a whole through the second connecting member 235, so that the risk of the positive electrode sheet 231 and the negative electrode sheet 232 falling off after compounding due to cutting is lower.

[0219] Please refer to Figure 22 、 Figure 24 and Figure 25 In some embodiments, the isolation membrane 233 includes a first membrane 2331 and a second membrane 2332 ; The step of feeding the separator 233, the negative electrode sheet 232 and the positive electrode sheet 231 into the winding mechanism 2000 for winding to form an electrode assembly wound body includes: S410, placing the positive electrode sheet 231 on the top side of the first separator 2331, placing the second separator 2332 on the top side of the positive electrode sheet 231, and placing the negative electrode sheet 232 on the top side of the second separator 2332; S420 , feeding the first separator 2331 , the second separator 2332 , the positive electrode sheet 231 and the negative electrode sheet 232 into the winding mechanism 2000 for winding to form an electrode assembly winding body.

[0220] In this embodiment, the negative electrode sheet 232, the second separator 2332, the positive electrode sheet 231 and the first separator 2331 can be stacked in sequence from the top side to the bottom side; that is, the negative electrode sheet 232 is located at the top side, the second separator 2332 is used to separate the positive electrode sheet 231 and the negative electrode sheet 232, and the positive electrode sheet 231 is located between the second separator 2332 and the first separator 2331.

[0221] Among them, the above-mentioned positive electrode plate 231 is set on the top side of the first diaphragm 2331, which means that during the horizontal transmission of the positive electrode plate 231 and the first diaphragm 2331, the positive electrode plate 231 is located above the first diaphragm 2331 in the direction of gravity; similarly, the above-mentioned setting of the second diaphragm 2332 on the top side of the positive electrode plate 231 means that during the horizontal transmission of the second diaphragm 2332 and the positive electrode plate 231, the second diaphragm 2332 is located above the positive electrode plate 231 in the direction of gravity; the above-mentioned setting of the negative electrode plate 232 on the top side of the second diaphragm 2332 means that during the horizontal transmission of the second diaphragm 2332 and the negative electrode plate 232, the negative electrode plate 232 is located above the second diaphragm 2332 in the direction of gravity.

[0222] In this way, during the winding process of the winding mechanism 2000, the negative electrode sheet 232, the second separator 2332, the positive electrode sheet 231 and the first separator 2331 can be wound in a stacked manner from the top side to the bottom side to obtain the corresponding electrode assembly winding body.

[0223] Please refer to Figures 23 to 25 In some embodiments, the step of feeding the first separator 2331 , the second separator 2332 , the positive electrode sheet 231 , and the negative electrode sheet 232 into the winding mechanism 2000 to form an electrode assembly winding body includes: S421, rolling and compounding the positive electrode sheet 231 and the first separator 2331 to form a first wound material 236; S422, rolling and combining the negative electrode sheet 232 and the second separator 2332 to form a second wound material 237; S423 , feeding the first winding material 236 and the second winding material 237 into the winding mechanism 2000 and winding them to form an electrode assembly winding body.

[0224] In step S421, the positive electrode sheet 231 and the first separator 2331 can be rolled and laminated to form a first wound material 236. It should be understood that since the cut positive electrode sheets 231 are connected to form a whole by the first connector 234, the composite effect of the integrated positive electrode sheet 231 and the first separator 2331 is better during the roll-combination, and the probability of partial detachment of the positive electrode sheet 231 is lower.

[0225] In step S422, the negative electrode sheet 232 and the second separator 2332 may be rolled and laminated to form a first wound material 236. It should be understood that since the cut negative electrode sheet 232 is connected to form a whole by the second connector 235, the integrated negative electrode sheet 232 and the second separator 2332 are more effectively laminated during the roll-laminated process, and the probability of partial detachment of the negative electrode sheet 232 is lower.

[0226] It can be understood that the order of step S421 and step S422 can be interchanged; or, step S421 and step S422 can be performed simultaneously.

[0227] In step S423, the first and second winding materials 236, 237, respectively obtained by roll-combining, can be fed into the winding mechanism 2000 and wound to form an electrode assembly wound body. Alternatively, the first and second winding materials 236, 237 can be fed into the winding mechanism 2000 independently; or, the first and second winding materials 236, 237 can be rolled again and then fed into the winding mechanism 2000 for winding.

[0228] With such an arrangement, the positive electrode sheet 231 and the first separator 2331 can be rolled and compounded to form the first wound material 236, and the negative electrode sheet 232 and the second separator 2332 can be rolled and compounded to form the second wound material 237, and then the first wound material 236 and the second wound material 237 can be fed into the winding mechanism 2000 and wound to form an electrode assembly wound body, so as to improve the compactness of the electrode assembly wound body; wherein, after the positive electrode sheet 231 is cut, it is connected to form a whole through the first connecting member 234, and after the negative electrode sheet 232 is cut, it is connected to form a whole through the second connecting member 235, so that the risk of the positive electrode sheet 231 and the negative electrode sheet 232 falling off easily after compounding due to cutting is lower.

[0229] Please refer to Figures 25 to 27 In some embodiments, before the step of feeding the first winding material 236 and the second winding material 237 into the winding mechanism 2000 and winding them to form an electrode assembly wound body, the following steps are included: S422a, rolling and compounding the first wound incoming material 236 and the second wound incoming material 237.

[0230] In this embodiment, the first winding material 236 and the second winding material 237 obtained by the rolling compounding operation can be rolled compounded again, and then the first winding material 236 and the second winding material 237 formed into one by rolling compounding are sent to the winding mechanism 2000 for winding.

[0231] The first wound material 236 may be the first wound material 236 formed by rolling and compounding the positive electrode sheet 231 and the first separator 2331 as in the above-mentioned embodiment; or, the first wound material 236 may be the first wound material 236 formed by rolling and compounding the negative electrode sheet 232 and the first separator 2331 as in the above-mentioned other embodiment.

[0232] Similarly, the second wound material 237 can be the second wound material 237 formed by rolling and compounding the positive electrode sheet 231 and the second separator 2332 as in the above-mentioned embodiment; or, the second wound material 237 can be the second wound material 237 formed by rolling and compounding the negative electrode sheet 232 and the second separator 2332 as in another above-mentioned embodiment.

[0233] Such an arrangement can further improve the compactness of the wound electrode assembly.

[0234] Please refer to Figure 25 、 Figure 28 and Figure 29 In some embodiments, the step of feeding the first separator 2331 , the second separator 2332 , the positive electrode sheet 231 , and the negative electrode sheet 232 into the winding mechanism 2000 to form an electrode assembly winding body includes: S421, rolling and combining the positive electrode sheet 231, the second separator 2332 and the negative electrode sheet 232 to form a third wound material 238; S422 , feeding the third winding material 238 and the first separator 2331 into the winding mechanism 2000 and winding them to form an electrode assembly winding body.

[0235] In step S421, the positive electrode sheet 231, the second separator 2332 and the negative electrode sheet 232 can be roll-combined at the same time, that is, the positive electrode sheet 231 and the negative electrode sheet 232 can be respectively arranged on opposite sides of the second separator 2332, and then the positive electrode sheet 231, the second separator 2332 and the negative electrode sheet 232 are roll-combined to form a third wound material 238.

[0236] In step S422, the first separator 2331 and the third wound material 238 obtained by roll-combining can be fed into the winding mechanism 2000 and wound to form an electrode assembly wound body. Alternatively, the third wound material 238 and the first separator 2331 can be fed into the winding mechanism 2000 independently; or the third wound material 238 and the first separator 2331 can be rolled again and then fed into the winding mechanism 2000 for winding.

[0237] With such an arrangement, the positive electrode sheet 231, the second separator 2332 and the negative electrode sheet 232 can be first rolled and compounded to form a third wound material 238, and then the third wound material 238 and the first separator 2331 can be fed into the winding mechanism 2000 and wound to form an electrode assembly wound body, so as to improve the compactness of the electrode assembly wound body; at the same time, after the positive electrode sheet 231 is cut, it is connected to form a whole through the first connecting member 234, and after the negative electrode sheet 232 is cut, it is connected to form a whole through the second connecting member 235, so that the risk of the cut positive electrode sheet 231 and the negative electrode sheet 232 falling off after the compounding operation is lower.

[0238] Please refer to Figure 25 and Figure 30 In some embodiments, before the step of feeding the first separator 2331 , the second separator 2332 , the positive electrode sheet 231 , and the negative electrode sheet 232 into the winding mechanism 2000 for winding to form an electrode assembly wound body, the following steps are included: The first separator 2331 , the positive electrode sheet 231 , the second separator 2332 and the negative electrode sheet 232 are rolled and laminated.

[0239] In this embodiment, before the winding operation, the first diaphragm 2331, the positive electrode sheet 231, the second diaphragm 2332 and the negative electrode sheet 232 can be rolled and composited so that the first diaphragm 2331, the positive electrode sheet 231, the second diaphragm 2332 and the negative electrode sheet 232 are rolled and composited into one piece, and then the rolled and composited material is fed into the winding mechanism 2000 to be wound to form an electrode assembly winding body.

[0240] Such an arrangement can further improve the compactness of the wound electrode assembly.

[0241] Please refer to Figure 25 and Figure 31 In some embodiments, the step of feeding the first separator 2331 , the second separator 2332 , the positive electrode sheet 231 , and the negative electrode sheet 232 into the winding mechanism 2000 to form an electrode assembly winding body includes: The positive electrode sheet 231 , the negative electrode sheet 232 , the first separator 2331 and the second separator 2332 are independently fed into the winding mechanism 2000 for winding to form an electrode assembly winding body.

[0242] Among them, the positive electrode sheet 231, the negative electrode sheet 232, the first separator 2331 and the second separator 2332 are independently fed into the winding mechanism 2000; that is, the positive electrode sheet 231, the negative electrode sheet 232, the first separator 2331 and the second separator 2332 can be separately unwound by different unwinding mechanisms, and then independently fed into the winding mechanism 2000, and the positive electrode sheet 231, the negative electrode sheet 232, the first separator 2331 and the second separator 2332 are wound by the winding mechanism 2000 to form an electrode assembly wound body.

[0243] With such an arrangement, the positive electrode sheet 231, the negative electrode sheet 232, the first separator 2331 and the second separator 2332 can be fed independently and fed into the winding mechanism 2000 to be wound into an electrode assembly winding body; and the positive electrode sheet 231 is cut and connected to form a whole through the first connecting member 234, and the negative electrode sheet 232 is cut and connected to form a whole through the second connecting member 235, so that the integrity of the cut positive electrode sheet 231 and the negative electrode sheet 232 when winding is better, which can effectively reduce the probability of the cut positive electrode sheet 231 being loose.

[0244] Below, the manufacturing method of the electrode assembly 23 provided in this application will be introduced in detail according to specific implementation methods.

[0245] Please refer to Figure 5 、 Figure 6 and Figure 32 In one embodiment, the method for manufacturing the electrode assembly 23 includes: S10a, providing a separator 233, a negative electrode sheet 232 and a positive electrode sheet 231; S20a, cutting the positive electrode sheet 231; S30a, providing a soft first connecting member 234, covering the corresponding cut portion of the positive electrode sheet 231, and connecting the first connecting member 234 with the cut positive electrode sheet 231 to form a whole; S40a, feeding the positive electrode sheet 231 into the first buffer mechanism 3000, wherein the first buffer mechanism 3000 has a positive electrode sheet 231 of a preset length buffered therein; the first buffer mechanism 3000 is configured to maintain the rate at which the positive electrode sheet 231 is fed into the winding mechanism 2000 by releasing the positive electrode sheet 231 buffered therein; S50a, feeding the separator 233, the negative electrode sheet 232 and the positive electrode sheet 231 into the winding mechanism 2000 for winding to form an electrode assembly winding body; S60a, shaping the electrode assembly winding to obtain an electrode assembly 23 with a flat structure; wherein the electrode assembly 23 has a straight area 230a and bending areas 230b located at opposite ends of the straight area 230a, and at least a portion of the first connecting member 234 is located in the bending area 230b.

[0246] In step S20a, in the winding direction S of the winding mechanism 2000, the leading section of the positive electrode sheet 231 is cut to form a positive electrode main section 2311 and at least one positive electrode laminate section 2312, with the at least one positive electrode laminate section 2312 located upstream of the positive electrode main section 2311. Furthermore, / or, in the winding direction S of the winding mechanism 2000, the trailing section of the positive electrode sheet 231 is cut to form a positive electrode main section 2311 and at least one positive electrode laminate section 2312, with the at least one positive electrode laminate section 2312 located downstream of the positive electrode main section 2311.

[0247] Please refer to Figure 18 、 Figure 19 and Figure 33 In another embodiment, the manufacturing method of the electrode assembly 23 includes: S10b, providing a separator 233, a negative electrode sheet 232 and a positive electrode sheet 231; S20b, cutting the positive electrode sheet 231; S30b, providing a soft first connecting member 234, covering the corresponding cut portion of the positive electrode sheet 231, and connecting the first connecting member 234 with the cut positive electrode sheet 231 to form a whole; S40b, feeding the positive electrode sheet 231 into the first buffer mechanism 3000, wherein the first buffer mechanism 3000 has a positive electrode sheet 231 of a preset length buffered therein; the first buffer mechanism 3000 is configured to maintain the rate at which the positive electrode sheet 231 is fed into the winding mechanism 2000 by releasing the positive electrode sheet 231 buffered therein; S50b, cutting off the negative electrode sheet 232; S60b, providing a soft second connecting member 235, covering the corresponding cut portion of the negative electrode sheet 232, and connecting the second connecting member 235 with the cut negative electrode sheet 232 to form a whole; S70b, feeding the negative electrode sheet 232 into the second buffer mechanism 4000, wherein the second buffer mechanism 4000 has a negative electrode sheet 232 of a preset length buffered therein; the second buffer mechanism 4000 is configured to maintain the rate at which the negative electrode sheet 232 is fed into the winding mechanism 2000 by releasing the negative electrode sheet 232 buffered therein; S80b, feeding the separator 233, the negative electrode sheet 232 and the positive electrode sheet 231 into the winding mechanism 2000 for winding to form an electrode assembly winding body; S90b. Shaping the electrode assembly winding body to obtain an electrode assembly 23 with a flat structure; wherein the electrode assembly 23 has a straight area 230a and bending areas 230b located at opposite ends of the straight area 230a, at least a portion of the first connecting member 234 is located in the bending area 230b, and at least a portion of the second connecting member 235 is located in the bending area 230b.

[0248] In step S20b, the leading portion of the positive electrode sheet 231 is cut in the winding direction S of the winding mechanism 2000 to form a positive electrode main portion 2311 and at least one positive electrode laminate portion 2312, with the at least one positive electrode laminate portion 2312 located upstream of the positive electrode main portion 2311. Furthermore, / or, the trailing portion of the positive electrode sheet 231 is cut in the winding direction S of the winding mechanism 2000 to form a positive electrode main portion 2311 and at least one positive electrode laminate portion 2312, with the at least one positive electrode laminate portion 2312 located downstream of the positive electrode main portion 2311.

[0249] In step S50b, in the winding direction S of the winding mechanism 2000, the leading portion of the negative electrode sheet 232 is cut to form a negative electrode main portion 2321 and at least one negative electrode laminate portion 2322, with the at least one negative electrode laminate portion 2322 located upstream of the negative electrode main portion 2321. And / or, in the winding direction S of the winding mechanism 2000, the trailing portion of the negative electrode sheet 232 is cut to form a negative electrode main portion 2321 and at least one negative electrode laminate portion 2322, with the at least one negative electrode laminate portion 2322 located downstream of the negative electrode main portion 2321.

[0250] Please refer to Figures 4 to 6 , an embodiment of the present application further provides an electrode assembly 23, and the electrode assembly 23 is prepared by the manufacturing method of the electrode assembly 23 as described above.

[0251] The electrode assembly 23 provided in the embodiment of the present application is prepared by adopting the above-mentioned manufacturing method of the electrode assembly 23. In this way, the reliability of the electrode assembly 23 is better.

[0252] Please refer to Figure 3 and Figure 6 The embodiment of the present application further provides a battery cell 20 , which includes a housing and the electrode assembly 23 as described above, and the electrode assembly 23 is accommodated in the housing.

[0253] The battery cell 20 provided in the embodiment of the present application includes the electrode assembly 23 as described above, so that the reliability of the battery cell is better.

[0254] Please refer to Figure 2 and Figure 3The embodiment of the present application further provides a battery device 100 , which includes the battery cell 20 as described above.

[0255] The battery device 100 provided in the embodiment of the present application includes the battery cell 20 as described above. Thus, the reliability of the battery device 100 is improved.

[0256] Please refer to Figure 1 and Figure 2 The embodiment of the present application further provides an electrical device, which includes the battery cell 20 as described above, or includes the battery device 100 as described above; the battery cell 20 or the battery device 100 is used to provide electrical energy.

[0257] The electrical device provided in the embodiment of the present application includes the battery cell or the battery device as described above, thereby improving the reliability of the electrical device.

[0258] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for manufacturing an electrode assembly, characterized in that: The method comprises: Provide separator, negative electrode sheet and positive electrode sheet; Cutting the positive electrode sheet; Providing a soft first connecting member, covering the corresponding cut portion of the positive electrode sheet, and connecting the first connecting member with the cut positive electrode sheet to form a whole; Feeding the separator, the negative electrode sheet and the positive electrode sheet into a winding mechanism for winding to form an electrode assembly winding body; The electrode assembly winding body is shaped to obtain an electrode assembly with a flat structure; wherein the electrode assembly has a straight area and bending areas located at opposite ends of the straight area, and at least a portion of the first connecting member is located in the bending area.

2. The method for manufacturing an electrode assembly according to claim 1, wherein: The step of cutting the positive electrode sheet includes: In the winding direction of the winding mechanism, the first section of the positive electrode sheet is cut to form a positive electrode main body and at least one positive electrode laminate portion, and the at least one positive electrode laminate portion is located upstream of the positive electrode main body portion.

3. The method for manufacturing an electrode assembly according to claim 2, wherein: The step of shaping the electrode assembly wound body to obtain an electrode assembly with a flat structure includes: The negative electrode sheet includes a plurality of negative straight portions formed in the straight area, and at least one positive electrode lamination portion is located between any two adjacent negative straight portions.

4. The method for manufacturing an electrode assembly according to claim 3, wherein: At least one of the positive electrode lamination portions is located between a first negative electrode straight portion and a second negative electrode straight portion among the plurality of negative electrode straight portions.

5. The method for manufacturing an electrode assembly according to any one of claims 1 to 4, characterized in that: The step of cutting the positive electrode sheet includes: In the winding direction of the winding mechanism, the end section of the positive electrode sheet is cut to form a positive electrode main body and at least one positive electrode laminate portion, and the at least one positive electrode laminate portion is located downstream of the positive electrode main body portion.

6. The method for manufacturing an electrode assembly according to claim 5, wherein: The step of shaping the electrode assembly wound body to obtain an electrode assembly with a flat structure includes: The negative electrode sheet includes n negative electrode straight portions formed in the straight area; at least one of the positive electrode laminate portions is located between two adjacent negative electrode straight portions; and / or at least one of the positive electrode laminate portions is wound to the outside of at least one of the nth negative electrode straight portion and the n-1th negative electrode straight portion of the n negative electrode straight portions.

7. The method for manufacturing an electrode assembly according to any one of claims 1 to 4 and 6, characterized in that: Before the step of feeding the separator, the negative electrode sheet, and the positive electrode sheet into a winding mechanism for winding to form an electrode assembly wound body, the method further includes: The positive electrode sheet is fed into a first buffer mechanism, in which a preset length of the positive electrode sheet is cached; the first buffer mechanism is configured to maintain the rate at which the positive electrode sheet is fed into the winding mechanism by releasing the positive electrode sheet cached therein.

8. The method for manufacturing an electrode assembly according to any one of claims 2 to 4 and 6, characterized in that: Before the step of feeding the separator, the negative electrode sheet, and the positive electrode sheet into a winding mechanism for winding to form an electrode assembly wound body, the method further includes: Cutting the negative electrode sheet; Providing a soft second connecting member, covering the corresponding cut portion of the negative electrode plate, and connecting the second connecting member with the cut negative electrode plate to form a whole; The step of shaping the electrode assembly wound body to obtain an electrode assembly with a flat structure includes: At least a portion of the second connecting member is located in the bending zone.

9. The method for manufacturing an electrode assembly according to claim 8, wherein: The step of cutting the negative electrode sheet includes: In the winding direction of the winding mechanism, the first section of the negative electrode sheet is cut to form a negative electrode main body and at least one negative electrode laminate portion, and the at least one negative electrode laminate portion is located upstream of the negative electrode main body portion.

10. The method for manufacturing an electrode assembly according to claim 9, wherein: The step of shaping the electrode assembly wound body to obtain an electrode assembly with a flat structure includes: The negative electrode main body includes a plurality of negative electrode straight portions formed in the straight area, at least one negative electrode laminate portion and at least two positive electrode laminate portions are located between a first negative electrode straight portion and a second negative electrode straight portion among the plurality of negative electrode straight portions, and the positive electrode laminate portions are provided on opposite sides of any one of the negative electrode laminate portions.

11. The method for manufacturing an electrode assembly according to claim 8, wherein: The step of cutting the negative electrode sheet includes: In the winding direction of the winding mechanism, the end section of the negative electrode sheet is cut to form a negative electrode main body and at least one negative electrode laminate portion, and the at least one negative electrode laminate portion is located downstream of the negative electrode main body portion.

12. The method for manufacturing an electrode assembly according to claim 11, wherein: The step of shaping the electrode assembly wound body to obtain an electrode assembly with a flat structure includes: The negative electrode main body includes n negative electrode straight portions formed in the straight area; at least one positive electrode laminate portion and at least one negative electrode laminate portion are located outside at least one of the nth negative electrode straight portion and the n-1th negative electrode straight portion of the n negative electrode straight portions.

13. The method for manufacturing an electrode assembly according to claim 8, wherein: Before the step of feeding the separator, the negative electrode sheet, and the positive electrode sheet into a winding mechanism for winding to form an electrode assembly wound body, the method further includes: The negative electrode sheet is fed into a second buffer mechanism, in which a preset length of the negative electrode sheet is buffered; the second buffer mechanism is configured to maintain the rate at which the negative electrode sheet is fed into the winding mechanism by releasing the negative electrode sheet buffered therein.

14. The method for manufacturing an electrode assembly according to any one of claims 1 to 4, 6 and 9 to 13, characterized in that: The winding direction of the winding mechanism is clockwise; or, the winding direction of the winding mechanism is counterclockwise.

15. The method for manufacturing an electrode assembly according to claim 14, wherein: The isolation membrane includes a first membrane and a second membrane; The step of feeding the separator, the negative electrode sheet, and the positive electrode sheet into a winding mechanism for winding to form an electrode assembly wound body comprises: Disposing the negative electrode sheet on the top side of the first diaphragm, disposing the second diaphragm on the top side of the negative electrode sheet, and disposing the positive electrode sheet on the top side of the second diaphragm; The first separator, the second separator, the positive electrode sheet and the negative electrode sheet are fed into a winding mechanism and wound to form an electrode assembly wound body.

16. The method for manufacturing an electrode assembly according to claim 15, wherein: The step of feeding the first separator, the second separator, the positive electrode sheet, and the negative electrode sheet into a winding mechanism and winding them to form an electrode assembly wound body comprises: Roll-compressing the negative electrode sheet and the first separator to form a first wound material; Roll-compressing the positive electrode sheet and the second separator to form a second wound material; The first wound material and the second wound material are fed into a winding mechanism and wound to form an electrode assembly wound body.

17. The method for manufacturing an electrode assembly according to claim 16, wherein: The isolation membrane includes a first membrane and a second membrane; The step of feeding the separator, the negative electrode sheet, and the positive electrode sheet into a winding mechanism for winding to form an electrode assembly wound body comprises: Disposing the positive electrode sheet on the top side of the first diaphragm, disposing the second diaphragm on the top side of the positive electrode sheet, and disposing the negative electrode sheet on the top side of the second diaphragm; The first separator, the second separator, the positive electrode sheet and the negative electrode sheet are fed into a winding mechanism and wound to form an electrode assembly wound body.

18. The method for manufacturing an electrode assembly according to claim 17, wherein: The step of feeding the first separator, the second separator, the positive electrode sheet, and the negative electrode sheet into a winding mechanism for winding to form an electrode assembly wound body comprises: Roll-compressing the positive electrode sheet and the first separator to form a first wound material; Roll-compressing the negative electrode sheet and the second separator to form a second wound material; The first wound material and the second wound material are fed into a winding mechanism and wound to form an electrode assembly wound body.

19. The method for manufacturing an electrode assembly according to claim 16 or 18, wherein: Before the step of feeding the first wound material and the second wound material into a winding mechanism and winding them to form an electrode assembly wound body, the method includes: The first wound material and the second wound material are roll-compounded.

20. The method for manufacturing an electrode assembly according to claim 15 or 17, wherein: The step of feeding the first separator, the second separator, the positive electrode sheet, and the negative electrode sheet into a winding mechanism for winding to form an electrode assembly wound body comprises: Roll-compressing the positive electrode sheet, the second separator and the negative electrode sheet to form a third wound material; The third winding material and the first separator are fed into a winding mechanism and wound to form an electrode assembly winding body.

21. The method for manufacturing an electrode assembly according to claim 15 or 17, wherein: The step of feeding the first separator, the second separator, the positive electrode sheet, and the negative electrode sheet into a winding mechanism for winding to form an electrode assembly wound body comprises: The first separator, the positive electrode sheet, the second separator and the negative electrode sheet are rolled and composited.

22. The method for manufacturing an electrode assembly according to claim 15 or 17, wherein: The step of feeding the first separator, the second separator, the positive electrode sheet, and the negative electrode sheet into a winding mechanism for winding to form an electrode assembly wound body comprises: The positive electrode sheet, the negative electrode sheet, the first separator and the second separator are independently fed into the winding mechanism and wound to form the electrode assembly wound body.

23. An electrode assembly, characterized in that: The electrode assembly is prepared by the method for manufacturing an electrode assembly according to any one of claims 1 to 22.

24. A battery cell, characterized in that: The battery cell includes a housing and the electrode assembly according to claim 23 , wherein the electrode assembly is accommodated in the housing.

25. A battery device, characterized in that: The battery device includes the battery cell according to claim 24 .

26. An electrical device, characterized in that: The electrical device includes the battery cell according to claim 24, or includes the battery device according to claim 25; the battery cell or the battery device is used to provide electrical energy.

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