Battery monomer, battery device, power utilization device and preparation method of electrode assembly

Abstract

The invention discloses a battery monomer, a battery device, a power utilization device and a preparation method of an electrode assembly. The battery monomer provided by the invention comprises a shell assembly and an electrode assembly, wherein the shell assembly is provided with an accommodating space; the electrode assembly is arranged in the accommodating space; wherein the electrode assembly comprises an anode pole piece, a cathode pole piece and a diaphragm for separating the anode pole piece from the cathode pole piece, the electrode assembly is wound, and a central hole is formed in the electrode assembly; the interlayer spacing in at least partial area of the electrode assembly arranged in the circumferential direction of the electrode assembly is set to be gradually reduced from the first preset number of turns along with the increase of the number of turns of winding and to be ended after the second preset number of turns, the second preset number of turns is larger than the first preset number of turns, and the first preset number of turns is arranged close to the center hole. Therefore, the interlayer spacing of the partial region close to the central hole is larger than the interlayer spacing of the partial region far away from the central hole, so that the risk of collapse of the central hole is relieved, and the reliability of the battery monomer is improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method for preparing a battery cell, a battery device, an electrical device and an electrode assembly. Background Art

[0002] Energy conservation and emission reduction are the key to sustainable development, which has promoted the adjustment of energy structure and the development and application of battery technology. The key to the development of battery technology lies in electrochemical energy storage technology. Due to its high energy density, good cycle capacity, high operating voltage, environmental protection and low self-discharge, it has been widely used in portable electronics, electric vehicles and energy storage systems. In order to improve the energy capacity and charging speed of battery devices, wound batteries came into being.

[0003] The battery includes one or more battery cells, each of which contains an electrode assembly. The electrode assembly is mainly formed by winding or stacking pole sheets. As the number of cycles of the battery device increases, the expansion force of the pole sheets will continue to increase. Usually, the closer the pole sheet is to the middle of the electrode assembly, the more obvious the increase in expansion force will be, making the middle of the electrode assembly more prone to collapse and other problems, which seriously affects the performance of the battery. Summary of the invention

[0004] The main purpose of the present application is to provide a method for preparing a battery cell, a battery device, an electrical device and an electrode assembly, aiming to solve the above-mentioned technical problems existing in the prior art.

[0005] To solve the above problems, the present application provides a battery cell, which includes a shell assembly and an electrode assembly, the shell assembly having a accommodating space; the electrode assembly is arranged in the accommodating space; wherein the electrode assembly includes an anode electrode sheet, a cathode electrode sheet and a diaphragm for spacing the anode electrode sheet and the cathode electrode sheet, the electrode assembly is wound and a center hole is formed inside the electrode assembly; wherein the interlayer spacing in at least a part of the area where the electrode assembly is arranged along its circumference is arranged to show a decreasing trend starting from a first predetermined number of turns with the increase of the number of winding turns, and the decreasing trend ends after a second predetermined number of turns, the second predetermined number of turns is greater than the first predetermined number of turns, and the first predetermined number of turns is arranged close to the center hole. Thus, the interlayer spacing in at least part of the area along the circumference of the electrode assembly shows a decreasing trend as the number of winding turns increases from the first predetermined number of turns, and ends the decreasing trend after the second predetermined number of turns, which can make the pole pieces far away from the center hole more compact, thereby improving the overall product strength of the electrode assembly after winding. At the same time, the interlayer spacing in at least part of the area of ​​the electrode assembly near the center hole can be greater than the interlayer spacing far away from the center hole, thereby providing a larger buffer space for the expansion of the pole piece near the center hole, thereby alleviating the risk of center hole collapse due to the increasing expansion force of the pole piece during the cycle aging process of the battery cell, thereby improving the reliability of the battery cell.

[0006] In some embodiments, the number of winding turns within the first range of turns defined by the first predetermined number of turns and the second predetermined number of turns is greater than or equal to 1 / 4 of the total number of winding turns of the electrode assembly. Thus, by making the number of winding turns within the first range of turns greater than or equal to 1 / 4 of the total number of winding turns, the risk of the center hole collapsing due to the small interlayer gap near the center hole or the small sum of all interlayer gaps near the center hole can be further improved, thereby improving the reliability of the battery cell.

[0007] In some embodiments, the number of winding turns within the first range of turns is less than or equal to 1 / 2 of the total number of winding turns. Thus, the risk of the center hole collapsing due to a small interlayer gap near the center hole or a small sum of all interlayer gaps near the center hole can be further improved, and the risk of poor performance of the electrode assembly due to insufficient compactness of the electrode assembly winding caused by a large gap between the pole pieces can also be alleviated.

[0008] In some embodiments, the first predetermined number of turns is greater than or equal to 1 and less than or equal to 5. Thus, the first predetermined number of turns is greater than or equal to 1 and less than or equal to 5, so that the starting number of turns within the predetermined winding number range is set closer to the center hole, thereby being more conducive to alleviating the risk of collapse of the center hole.

[0009] In some embodiments, the first predetermined number of turns is greater than 1, and the interlayer spacing from the innermost turn of the electrode assembly to the first predetermined number of turns remains constant or increases. Thus, the interlayer spacing from the innermost turn of the electrode assembly to the first predetermined number of turns remains constant or increases, which can alleviate the risk of poor performance of the electrode assembly due to insufficient compactness of the electrode assembly winding caused by the large gap between the pole pieces, and improve the structural stability of the battery cell.

[0010] In some embodiments, the second predetermined number of turns is greater than or equal to 1 / 3 of the total number of turns of the electrode assembly and less than or equal to 1 / 2 of the total number of turns. Thus, by setting the position of the second predetermined number of turns, the second predetermined number of turns is closer to the center hole, which is more conducive to alleviating the risk of collapse of the center hole.

[0011] In some embodiments, within the first number of turns defined by the first predetermined number of turns and the second predetermined number of turns, the interlayer spacing of at least some regions is set to decrease linearly or nonlinearly with the increase of the number of winding turns. Thus, the interlayer spacing of at least some regions within the first number of turns decreases linearly or nonlinearly with the increase of the number of winding turns, which facilitates the manufacturing and forming of the electrode assembly and improves the risk of the central hole collapsing due to the increasing expansion force of the pole piece, thereby improving the reliability of the battery cell.

[0012] In some embodiments, within the first number of turns defined by the first predetermined number of turns and the second predetermined number of turns, the interlayer spacing of at least some regions is set to decrease in a step-by-step manner as the number of winding turns increases. Thus, within the first number of turns, the interlayer spacing of at least some regions is set to decrease in a step-by-step manner as the number of winding turns increases, which facilitates the manufacturing and forming of the electrode assembly and improves the risk of the central hole collapsing due to the increasing expansion force of the pole piece, thereby improving the reliability of the battery cell.

[0013] In some embodiments, within the first number of turns defined by the first predetermined number of turns and the second predetermined number of turns, the ratio of the maximum value to the minimum value of the interlayer spacing in at least a portion of the region is greater than or equal to 1.5, and less than or equal to 3. Thus, by setting the ratio relationship between the maximum value and the minimum value of the interlayer spacing, the risk of the center hole collapsing due to the small interlayer gap near the center hole or the small sum of all interlayer gaps near the center hole can be further improved, and the risk of poor performance of the electrode assembly due to the large gap between the pole pieces causing the electrode assembly to be wound less compactly can also be alleviated.

[0014] In some embodiments, the interlayer spacing is the gap between the main surfaces of two anode pole pieces or two cathode pole pieces facing each other of two adjacent turns, and within the first turn range defined by the first predetermined turn number and the second predetermined turn number, the difference between the maximum and minimum values ​​of the interlayer spacing in at least part of the region is greater than or equal to 5μm and less than or equal to 26μm. Thus, the risk of the central hole collapsing due to the small interlayer gap near the central hole or the small sum of all interlayer gaps near the central hole can be further improved, and the risk of poor performance of the electrode assembly due to the large gap between the pole pieces causing the electrode assembly to be wound less compactly can also be alleviated.

[0015] In some embodiments, the head end of the cathode electrode piece is located between two adjacent circles of anode electrode pieces, and the head end of the cathode electrode piece is located in at least a portion of the region. Thus, the head end of the cathode electrode piece is located between two adjacent circles of anode electrode pieces, and the head end of the cathode electrode piece is located in at least a portion of the region, which can better improve the phenomenon of obvious pressure concentration at the cathode electrode piece, further alleviate the risk of central hole collapse, and improve the reliability of the battery cell.

[0016] In some embodiments, at least part of the area is a local area arranged along the circumference of the electrode assembly. Thus, the risk of the center hole collapsing due to the small interlayer gap near the center hole or the small sum of all interlayer gaps near the center hole can be improved, and the risk of poor performance of the electrode assembly due to the large gap between the pole pieces causing the electrode assembly to be wound less compactly can also be alleviated.

[0017] In some embodiments, the local area is a fan-shaped area, and the central angle of the local area is greater than or equal to 90 degrees. Therefore, the central angle of the local area is greater than or equal to 90 degrees, which can further improve the risk of the central hole collapsing due to the small interlayer gap near the central hole or the small sum of all interlayer gaps near the central hole.

[0018] In some embodiments, within the first number of turns defined by the first predetermined number of turns and the second predetermined number of turns, the interlayer spacing outside the local area is set to remain constant as the number of winding turns increases. Thus, the interlayer spacing outside the local area is set to remain constant as the number of winding turns increases, which facilitates the manufacturing and forming of the electrode assembly and alleviates the risk of poor performance of the electrode assembly due to large gaps between most of the pole pieces of the electrode assembly, which makes the electrode assembly not wound compactly enough.

[0019] In some embodiments, within a second range of turns greater than the first range of turns defined by the first predetermined number of turns and the second predetermined number of turns, the interlayer spacing of at least a portion of the region is set to remain constant or increase with the increase in the number of winding turns, and the number of winding turns within the second range of turns is greater than or equal to 1 / 4 of the total number of winding turns of the electrode assembly. Thus, the interlayer spacing of at least a portion of the region within the second range of turns remains constant or increases with the increase in the number of winding turns, which can alleviate the risk of poor performance of the electrode assembly due to insufficient compactness of the electrode assembly winding caused by the large gap between the pole pieces, and improve the structural stability of the battery cell.

[0020] In some embodiments, the ratio of the number of winding turns within the first range of turns to the number of winding turns within the second range of turns is between 1 / 3 and 2. Thus, the ratio of the number of winding turns within the first range of turns to the number of winding turns within the second range of turns is between 1 / 3 and 2, which can improve the risk of the center hole collapsing due to the small interlayer gap near the center hole or the small sum of all interlayer gaps near the center hole, and can also alleviate the risk of poor performance of the electrode assembly due to the large gap between the pole pieces, which makes the electrode assembly not wound compactly.

[0021] In order to solve the above problems, the present application also provides a battery device, which includes the above battery cell.

[0022] In order to solve the above problems, the present application also provides an electrical device, which includes the above battery device.

[0023] To solve the above problems, the present application also provides a method for preparing an electrode assembly, the preparation method comprising: providing an anode electrode sheet, a cathode electrode sheet and a diaphragm; winding the anode electrode sheet, the cathode electrode sheet and the diaphragm to form an electrode assembly with a central hole inside; wherein the interlayer spacing in at least a partial area of ​​the electrode assembly arranged along its circumference is arranged to show a decreasing trend starting from a first predetermined number of turns with the increase of the number of winding turns, and the decreasing trend ends after a second predetermined number of turns, the second predetermined number of turns is greater than the first predetermined number of turns, the first predetermined number of turns is arranged close to the central hole, and the number of winding turns within a first number of turns defined by the first predetermined number of turns and the second predetermined number of turns is greater than or equal to 1 / 4 of the total number of winding turns of the electrode assembly. Thus, the interlayer spacing in at least part of the area of ​​the electrode assembly arranged along its circumference shows a decreasing trend as the number of winding turns increases from the first predetermined number of turns, and the decreasing trend ends after the second predetermined number of turns, which can make the pole pieces far away from the center hole more compact, improve the overall product strength of the electrode assembly after winding, and at the same time, it can also make the interlayer spacing of at least part of the area of ​​the electrode assembly near the center hole larger than the interlayer spacing far away from the center hole, thereby providing a larger buffer space for the expansion of the pole pieces near the center hole, thereby alleviating the risk of the center hole collapsing due to the increasing expansion force of the pole pieces during the cycle aging of the battery cell, and improving the reliability of the battery cell. At the same time, by making the number of winding turns within the first number of turns greater than or equal to 1 / 4 of the total number of winding turns, the risk of the center hole collapsing due to the small interlayer gap near the center hole or the small sum of all interlayer gaps near the center hole can be further improved, thereby improving the reliability of the battery cell.

[0024] In some embodiments, the anode electrode plate, the cathode electrode plate and the diaphragm are wound, including: setting at least one or a combination of the thickness of the phase change coating, the thickness of the polymer particle coating and the bump height in at least a partial area to show a decreasing trend as the number of winding turns increases; and / or, setting the winding tension in at least a partial area to show an increasing trend as the number of winding turns increases. Therefore, by adjusting at least one or a combination of the thickness of the phase change coating, the thickness of the polymer particle coating, the height of the bumps and the winding tension in at least part of the area, it is advantageous to set the interlayer spacing in at least part of the area to show a decreasing trend as the number of winding turns increases from a first predetermined number of turns, and end the decreasing trend after a second predetermined number of turns. This can make the pole pieces away from the center hole more compact, thereby improving the overall product strength of the electrode assembly after winding. At the same time, it can also make the interlayer spacing of at least part of the area of ​​the electrode assembly near the center hole greater than the interlayer spacing away from the center hole, thereby providing a larger buffer space for the expansion of the pole piece near the center hole, thereby alleviating the risk of center hole collapse due to the increasing expansion force of the pole piece during the battery cell aging process, thereby improving the reliability of the battery cell.

[0025] In some embodiments, the winding operation of the anode electrode sheet, the cathode electrode sheet and the separator includes: setting the thickness of the phase change coating in at least part of the area to be decreasing with the increase of the number of winding turns; the preparation method further includes: after the winding is completed, changing the phase change coating from a solid state to a liquid or gaseous state. Thus, by changing the phase change coating from a solid state to a liquid or gaseous state after the winding is completed, the thickness of the phase change coating in at least part of the area is adjusted, so as to facilitate setting the interlayer spacing in at least part of the area to be decreasing with the increase of the number of winding turns from a first predetermined number of turns, and ending the decreasing trend after a second predetermined number of turns, so that the electrode sheets away from the center hole are more compact, and the overall product strength of the electrode assembly after winding is improved. At the same time, the interlayer spacing of at least part of the area of ​​the electrode assembly near the center hole is greater than the interlayer spacing at the position away from the center hole, thereby providing a larger buffer space for the expansion of the electrode sheet near the center hole, thereby alleviating the risk of the center hole collapsing due to the increasing expansion force of the electrode sheet during the cycle aging of the battery cell, and improving the reliability of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. 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 creative work.

[0027] Figure 1 is a schematic structural diagram of a vehicle according to one or more embodiments of the present application; Figure 2 is a schematic diagram of an exploded structure of a battery device according to one or more embodiments of the present application; Figure 3 is a schematic diagram of an exploded structure of a battery cell according to one or more embodiments of the present application; Figure 4 is a schematic diagram of a first cross-sectional structure of a battery cell according to one or more embodiments of the present application; Figure 5 is a schematic diagram of a second cross-sectional structure of a battery cell according to one or more embodiments of the present application; Figure 6 is a first schematic diagram of the interlayer spacing of a battery cell changing with the number of winding turns according to one or more embodiments of the present application; Figure 7 is a second schematic diagram of the interlayer spacing of a battery cell changing with the number of winding turns according to one or more embodiments of the present application; Figure 8is a third schematic diagram showing the variation of the interlayer spacing of a battery cell with the number of winding turns according to one or more embodiments of the present application; Fig. 9 is a fourth schematic diagram showing the variation of the interlayer spacing of a battery cell with the number of winding turns according to one or more embodiments of the present application; Fig.10 It is a schematic flow chart of a method for preparing an electrode assembly according to one or more embodiments of the present application.

[0028] Figure numbers: vehicle 1; battery device 2; controller 3; motor 4; housing 20; first part 21; second part 22; battery cell 10; shell assembly 100; shell 110; end cover 120; accommodating space 130; electrode assembly 200; anode electrode sheet 210; cathode electrode sheet 220; head end 221; diaphragm 230; center hole 240; interlayer spacing D; local area P; center angle A. DETAILED DESCRIPTION

[0029] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0031] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0032] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0033] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0034] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0035] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0036] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0037] At present, from the perspective of market development, the application of batteries is becoming more and more extensive. Batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of battery application areas, its market demand is also constantly expanding.

[0038] Batteries mentioned in this field can be divided into disposable batteries and rechargeable batteries according to whether they are rechargeable. Disposable batteries (Primary Battery) are also called "disposable" batteries and original batteries, because after they are exhausted, they can no longer be recharged and can only be discarded. Rechargeable batteries are also called secondary batteries (Secondary Battery) or secondary batteries, storage batteries. The manufacturing materials and processes of rechargeable batteries are different from those of primary batteries. Its advantage is that it can be recycled many times after charging, and the output current load capacity of rechargeable batteries is higher than that of most disposable batteries. The common types of rechargeable batteries at present are: lead-acid batteries, nickel-metal hydride batteries and lithium-ion batteries. Lithium-ion batteries have the advantages of light weight, large capacity (the capacity is 1.5 to 2 times that of nickel-metal hydride batteries of the same weight), no memory effect, and have a very low self-discharge rate. Therefore, even though the price is relatively high, they are still widely used. Lithium-ion batteries are currently also widely used in pure electric vehicles and hybrid vehicles. The capacity of lithium-ion batteries used for this purpose is relatively low, but they have a larger output and charging current, and also have a longer service life, but the cost is higher.

[0039] The battery described in the embodiments of the present application refers to a rechargeable battery or a disposable battery. The embodiments disclosed in the present application will be described below mainly by taking a lithium-ion battery as an example. It should be understood that the embodiments disclosed in the present application are applicable to any other appropriate type of rechargeable battery. The battery mentioned in the embodiments disclosed in the present application can be directly or indirectly applied to an appropriate device to power the device.

[0040] The present application provides an electric device, which may include but is not limited to mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. Among them, electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc., and spacecraft may include airplanes, rockets, space shuttles and spacecraft, etc. Among them, the electric device may include a battery device, and the electric device may provide electric energy through the battery device to realize the corresponding function.

[0041] Taking the electrical device as an electric vehicle as an example, the electric vehicle may include a battery device.

[0042] Please refer to Figure 1 , Figure 1 is a schematic diagram of the structure of a vehicle according to one or more embodiments of the present application.

[0043] The vehicle 1 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended range vehicle, etc. A battery device 2 is provided inside the vehicle 1, and the battery device 2 may be provided at the bottom, head or tail of the vehicle 1. The battery device 2 may be used to power the vehicle 1, for example, the battery device 2 may be used as an operating power source for the vehicle 1. The vehicle 1 may also include a controller 3 and a motor 4, and the controller 3 is used to control the battery device 2 to power the motor 4, for example, for starting, navigating and driving the vehicle 1.

[0044] In some embodiments of the present application, the battery device 2 can not only serve as an operating power source for the vehicle 1 , but also serve as a driving power source for the vehicle 1 , replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1 .

[0045] In order to improve the performance of the electrical device, the present application also provides a battery device, see Figure 2 , Figure 2 is a schematic diagram of the exploded structure of a battery device according to one or more embodiments of the present application.

[0046] The shape of the battery device 2 may include but is not limited to a square cylindrical shape or other arbitrary shapes.

[0047] In some embodiments, the battery device 2 may include a box and a battery cell 10, and the battery cell 10 is accommodated in the box. The box is used to provide a storage space 130 for the battery cell 10, and the box can adopt a variety of structures. In some embodiments, the box may include a first part 21 and a second part 22, and the first part 21 and the second part 22 cover each other, and the first part 21 and the second part 22 jointly define a storage space 130 for accommodating the battery cell 10. The second part 22 may be a hollow structure with one end open, and the first part 21 may be a plate-like structure, and the first part 21 covers the open side of the second part 22, so that the first part 21 and the second part 22 jointly define the storage space 130; the first part 21 and the second part 22 may also be hollow structures with one side open, and the open side of the first part 21 covers the open side of the second part 22.

[0048] In the battery device 2, there can be multiple battery cells 10, and the multiple battery cells 10 can be connected in series, in parallel, or in mixed connection. Mixed connection means that the multiple battery cells 10 are both connected in series and in parallel. Multiple battery cells 10 can be directly connected in series, in parallel, or in mixed connection, and then the whole formed by the multiple battery cells 10 is accommodated in the box; of course, the battery device 2 can also be a battery module formed by connecting multiple battery cells 10 in series, in parallel, or in mixed connection, and then the multiple battery modules are connected in series, in parallel, or in mixed connection to form a whole, and accommodated in the box. The battery device 2 can also include other structures. For example, the battery device 2 can also include a busbar component for realizing electrical connection between multiple battery cells 10.

[0049] The manufacturing method of the battery cell 10 mainly includes a winding method, that is, the battery cell 10 is mainly a wound battery. The wound battery is simple to manufacture, and the manufacturing and assembly processes have general requirements on equipment precision and high production efficiency.

[0050] The battery cell 10 may include one or more electrode assemblies 200, which are mainly formed by winding pole sheets. As the number of cycles of the battery device 2 increases, the expansion force of the pole sheets will continue to increase. Generally, the closer the pole sheet is to the middle of the electrode assembly 200, the more obvious the increase in expansion force will be, causing the middle of the electrode assembly 200 to be more prone to collapse and other problems, thereby seriously affecting the performance of the battery.

[0051] In order to solve the technical problems existing in the related art, the present application provides a method for preparing a battery cell, a battery device, an electric device and an electrode assembly. The electrode assembly of the battery cell is formed by winding pole pieces, and the spacing between the pole pieces near the center of the wound electrode assembly is larger than the spacing between the pole pieces far from the center, thereby providing a larger buffer space for the expansion of the pole pieces and improving the reliability of the battery cell.

[0052] Specifically, see Figure 3 and Figure 4 , Figure 3 is a schematic diagram of the exploded structure of a battery cell according to one or more embodiments of the present application, Figure 4 It is a schematic diagram of a first cross-sectional structure of a battery cell according to one or more embodiments of the present application.

[0053] The battery cell 10 includes a shell assembly 100 and an electrode assembly 200, the shell assembly 100 has a accommodating space 130; the electrode assembly 200 is arranged in the accommodating space 130; wherein the electrode assembly 200 includes an anode electrode sheet 210, a cathode electrode sheet 220 and a diaphragm 230 for spacing the anode electrode sheet 210 and the cathode electrode sheet 220, the electrode assembly 200 is wound and a center hole 240 is formed inside the electrode assembly 200; wherein the interlayer spacing D in at least a part of the area where the electrode assembly 200 is arranged along its circumference is arranged to show a decreasing trend starting from a first predetermined number of turns with the increase of the number of winding turns, and the decreasing trend ends after a second predetermined number of turns, the second predetermined number of turns is greater than the first predetermined number of turns, and the first predetermined number of turns is arranged close to the center hole 240.

[0054] The housing assembly 100 may include a housing 110 and an end cap 120, wherein the end cap 120 refers to a component that covers the opening of the housing 110 to isolate the internal environment of the battery cell 10 from the external environment. Without limitation, the shape of the end cap 120 may be adapted to the shape of the housing 110 to match the housing 110. Optionally, the end cap 120 may be made of a material with a certain hardness and strength (such as an aluminum alloy), so that the end cap 120 is not easily deformed when it is squeezed and collided, so that the battery cell 10 can have a higher structural strength and the safety performance can also be improved. Functional components such as electrode terminals may be provided on the end cap 120. The electrode terminal may be used to electrically connect to the electrode assembly 200 for outputting or inputting electrical energy of the battery cell 10. In some embodiments, the electrode terminal may include a pole. The pole may include a positive pole and a negative pole for outputting current and connecting to an external circuit. In some embodiments, the end cap 120 may also be provided with an explosion-proof component for releasing the internal pressure when the internal pressure or temperature of the battery cell 10 reaches a threshold. The material of the end cap 120 may include, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. In some embodiments, an insulating member may be provided inside the end cap 120, and the insulating member may be used to isolate the electrical connection components in the housing 110 from the end cap 120 to reduce the risk of short circuit. Exemplarily, the insulating member may be plastic, rubber, etc.

[0055] The shell 110 is a component used to cooperate with the end cap 120 to form the internal environment of the battery cell 10, wherein the formed internal environment can be used to accommodate the electrode assembly 200, the electrolyte and other components. The shell 110 and the end cap 120 can be independent components, and an opening can be set on the shell 110, and the internal environment of the battery cell 10 is formed by covering the opening with the end cap 120 at the opening. Without limitation, the end cap 120 and the shell 110 can also be integrated. Specifically, the end cap 120 and the shell 110 can form a common connection surface before other components are put into the shell, and when it is necessary to encapsulate the interior of the shell assembly 100, the end cap 120 covers the shell 110. The shell 110 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 110 can be determined according to the specific shape and size of the electrode assembly 200. The material of the shell 110 may include but is not limited to copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0056] The electrode assembly 200 is a component in the battery cell 10 where electrochemical reactions occur. One or more electrode assemblies 200 may be included in the shell assembly 100. The electrode assembly 200 is mainly formed by winding an anode electrode sheet 210, a cathode electrode sheet 220, and a separator 230 for separating the anode electrode sheet 210 and the cathode electrode sheet 220. The parts of the anode electrode sheet 210 and the cathode electrode sheet 220 with active materials constitute the main body of the electrode assembly 200, and the parts of the anode electrode sheet 210 and the cathode electrode sheet 220 without active materials each constitute a tab. The anode tab and the cathode tab may be located together at one end of the main body or at both ends of the main body respectively. During the charge and discharge process of the battery, the anode active material and the cathode active material react with the electrolyte, and the tabs connect the electrode terminals to form a current loop.

[0057] Among them, the cathode electrode sheet 220 may include a cathode current collector and a cathode active material disposed on at least one surface of the cathode current collector. As an example, the cathode current collector has two surfaces opposite to each other in its own thickness direction, and the cathode active material is disposed on any one or both of the two opposite surfaces of the cathode current collector. As an example, the cathode current collector may be a metal foil or a composite current collector. For example, as a metal foil, aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc., treated with silver surface may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). The cathode active material may include, but is not limited to, lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds.

[0058] The anode electrode sheet 210 may include an anode current collector and an anode active material disposed on at least one surface of the anode current collector. The anode current collector may be a metal foil, a foamed metal or a composite current collector. For example, as a metal foil, aluminum or stainless steel treated with silver, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The foamed metal may be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). The negative electrode active material may include, but is not limited to, at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, etc.

[0059] The main material of the separator 230 can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator 230 can include but is not limited to a single-layer film, or a multi-layer composite film. When the separator 230 is a multi-layer composite film, the materials of each layer can be the same or different. The separator can be a separate component located between the positive and negative electrodes, or it can be attached to the surface of the positive and negative electrodes.

[0060] In the process of winding to form the electrode assembly 200, a winding needle can be set first, and then the anode electrode sheet 210, the cathode electrode sheet 220 and the separator 230 are wound on the winding needle at the same time until the electrode assembly 200 is wound, wherein the position of the electrode assembly 200 corresponding to the winding needle is formed as the center hole 240 inside the electrode assembly 200, and the center hole 240 is a through hole extending along the central axis of the electrode assembly 200. In the related art, as the battery cell 10 ages through the cycle, the thickness of the anode electrode sheet 210 and the cathode electrode sheet 220 will gradually increase, and a continuously increasing expansion force will be generated, thereby squeezing the center hole 240, resulting in the risk of the center hole 240 collapsing. The collapse of the center hole 240 will cause the battery cell 10 to have problems such as capacity loss, internal short circuit, thermal runaway, shortened life, performance fluctuations, etc.

[0061] In this embodiment, the interlayer spacing D in at least a part of the region of the electrode assembly 200 arranged along its circumference is arranged to be decreasing from the first predetermined number of turns as the number of winding turns increases, and the decreasing trend ends after the second predetermined number of turns, and the first predetermined number of turns is arranged close to the center hole 240. The interlayer spacing D of the electrode assembly 200 can be the gap between adjacent winding layers. For example, the interlayer spacing D can be the gap between the main surfaces of the anode pole pieces 210 of two adjacent turns separated by the cathode pole piece 220 and the separator 230 facing each other, or the interlayer spacing D can be the gap between the main surfaces of the cathode pole pieces 220 of two adjacent turns separated by the anode pole piece 210 and the separator 230 facing each other. The first predetermined number of turns is arranged close to the center hole 240. For example, when the total number of winding turns is thirty turns, the first predetermined number of turns can be the first turn, the second turn, the third turn, the fifth turn, or the sixth turn, etc., from the direction close to the center hole 240 to the direction away from the center hole 240.

[0062] At least a portion of the regions of the electrode assembly 200 arranged along its circumference may be: the electrode assembly 200 corresponding to all regions of the electrode assembly 200 along its circumference, or the electrode assembly 200 corresponding to at least a portion of the region of the electrode assembly 200 along its circumference, for example, the end surface of the electrode assembly 200 corresponding to the portion of the region may be fan-shaped, square, circular or other shapes. The interlayer spacing D in at least a portion of the region shows a decreasing trend with the increase of the number of winding turns from the first predetermined number of turns, and ends the decreasing trend after the second predetermined number of turns. For example, when the total number of winding turns is twenty turns, the first predetermined number of turns may be the first turn from the direction close to the center hole 240 to the direction away from the center hole 240, and the second predetermined number of turns may be the fifth turn from the direction close to the center hole 240 to the direction away from the center hole 240. The interlayer spacing D shows a decreasing trend between the first turn and the fifth turn, wherein the decreasing trend may be a regular decreasing trend or an irregular decreasing trend. In some application scenarios, the second predetermined number of turns may be the outermost turn of the electrode assembly 200 farthest from the center hole 240. For example, when the total number of turns is twenty, the first predetermined number of turns may be the first turn from close to the center hole 240 to far away from the center hole 240, and the second predetermined number of turns may be the twentieth turn. The interlayer spacing D shows a decreasing trend between the first and twentieth turns, that is, the interlayer spacing D shows a decreasing trend between the innermost and outermost turns of the electrode assembly 200. It should be noted that due to the existence of tolerance, the decreasing trend is not limited to decreasing turn by turn. In actual products, after obtaining a series of interlayer spacings D, it is possible to determine whether multiple interlayer spacings D meet the overall decreasing trend by using data fitting or local maximum methods.

[0063] Through the above-mentioned embodiment, the interlayer spacing D in at least a portion of the area of ​​the electrode assembly 200 arranged along its circumference shows a decreasing trend as the number of winding turns increases from the first predetermined number of turns, and the decreasing trend ends after the second predetermined number of turns, which can make the pole pieces away from the center hole 240 more compact, thereby improving the overall product strength of the electrode assembly 200 after winding. At the same time, the interlayer spacing D of at least a portion of the area of ​​the electrode assembly 200 near the center hole 240 can be greater than the interlayer spacing D away from the center hole 240, thereby providing a larger buffer space for the expansion of the pole piece near the center hole 240, thereby alleviating the risk of the center hole 240 collapsing due to the increasing expansion force of the pole piece during the cycle aging process of the battery cell 10, thereby improving the reliability of the battery cell 10.

[0064] In some embodiments, the number of winding turns within the first range of turns defined by the first predetermined number of turns and the second predetermined number of turns is greater than or equal to 1 / 4 of the total number of winding turns of the electrode assembly 200. The number of winding turns within the first range of turns is greater than or equal to 1 / 3, 1 / 2, 2 / 3, 3 / 4, etc. of the total number of winding turns of the electrode assembly 200. Specifically, the number of winding turns within the first range of turns may be 1 / 3, 1 / 2, 2 / 3, 3 / 4, etc. of the total number of winding turns. Exemplarily, when the first predetermined number of turns is the first turn from the direction close to the center hole 240 to the direction away from the center hole 240, and the second predetermined number of turns is the fifth turn from the direction close to the center hole 240 to the direction away from the center hole 240, the number of winding turns within the first range of turns is five turns. The number of winding turns within the first range of turns is greater than or equal to 1 / 4 of the total number of winding turns of the electrode assembly 200. For example, when the total number of winding turns is 20, the number of winding turns within the first range of turns may be five, six, seven, eight, etc. Thus, by making the number of winding turns within the first range of turns greater than or equal to 1 / 4 of the total number of winding turns, the risk of the center hole 240 collapsing due to a small interlayer gap near the center hole 240 or a small sum of all interlayer gaps near the center hole 240 can be further improved, thereby improving the reliability of the battery cell 10.

[0065] In some embodiments, the number of winding turns within the first range of turns is less than or equal to 1 / 2 of the total number of turns. The number of winding turns within the first range of turns may be less than or equal to 1 / 3 of the total number of turns and greater than or equal to 1 / 4, or less than or equal to 2 / 5 of the total number of turns and greater than or equal to 1 / 4, or less than or equal to 1 / 2 of the total number of turns and greater than or equal to 1 / 3, or less than or equal to 1 / 2 of the total number of turns and greater than or equal to 1 / 4, etc. Specifically, the number of winding turns within the first range of turns may be 1 / 2, 1 / 3, 1 / 4, 2 / 5, etc. of the total number of turns. Exemplarily, when the total number of winding turns is twenty turns, the number of winding turns within the first range of turns may be ten turns, nine turns, eight turns, seven turns, six turns, five turns, etc. In this way, the risk of the center hole 240 collapsing due to the small interlayer gap near the center hole 240 or the small sum of all interlayer gaps near the center hole 240 can be further improved. At the same time, the risk of the performance of the electrode assembly 200 deteriorating due to the electrode assembly 200 not being wound compactly enough due to the large gap between the pole pieces can be alleviated.

[0066] In some embodiments, the first predetermined number of turns is greater than or equal to 1 and less than or equal to 5. The first predetermined number of turns may be the first turn, the second turn, the third turn, the fourth turn, or the fifth turn. Optionally, the first predetermined number of turns is the first turn. Thus, the first predetermined number of turns is greater than or equal to 1 and less than or equal to 5, so that the starting number of turns within the predetermined winding turn range is set closer to the center hole 240, thereby alleviating the risk of the center hole 240 collapsing.

[0067] In some embodiments, the first predetermined number of turns is greater than 1, and the interlayer spacing D from the innermost circle of the electrode assembly 200 to the first predetermined number of turns remains constant or increases. The first predetermined number of turns may be two turns, three turns, four turns or more. Exemplarily, when the first predetermined number of turns is five turns, the interlayer spacing from the innermost circle to the fifth circle of the electrode assembly 200 remains constant or increases. Among them, the increasing trend may be a regular increasing trend or an irregular increasing trend, wherein the increasing trend may include but is not limited to linear increasing and nonlinear increasing. Thus, the interlayer spacing D from the innermost circle of the electrode assembly 200 to the first predetermined number of turns remains constant or increases, which can alleviate the risk of poor performance of the electrode assembly 200 due to insufficient compactness of the winding of the electrode assembly 200 caused by the large gap between the pole pieces, and improve the structural stability of the battery cell 10.

[0068] In some embodiments, the second predetermined number of turns is greater than or equal to 1 / 3 of the total number of winding turns of the electrode assembly and less than or equal to 1 / 2 of the total number of winding turns. Among them, the second predetermined number of turns may be greater than or equal to 1 / 3 of the total number of winding turns and less than or equal to 2 / 5 of the total number of winding turns, or the second predetermined number of turns may be greater than or equal to 3 / 7 of the total number of winding turns and less than or equal to 1 / 2 of the total number of winding turns, and so on. Specifically, the second predetermined number of turns may be 1 / 3, 2 / 5, 3 / 7, 1 / 2 of the total number of winding turns, and so on. Exemplarily, when the total number of winding turns is twelve turns, the second predetermined number of turns may be the sixth turn, the fifth turn, and the fourth turn. Thus, by setting the position of the second predetermined number of turns, the second predetermined number of turns is closer to the center hole 240, which is more conducive to alleviating the risk of collapse of the center hole 240.

[0069] In some embodiments, within the first number of turns defined by the first predetermined number of turns and the second predetermined number of turns, the ratio of the maximum value to the minimum value of the interlayer spacing D in at least a portion of the region is greater than or equal to 1.5, and less than or equal to 3. Among them, the ratio of the maximum value to the minimum value of the interlayer spacing D in at least a portion of the region may be between 1.6-2, or between 2-3, etc. Specifically, the ratio of the maximum value to the minimum value may be 1.5, 1.6, 1.8, 2, 2.1, 2.3, 2.6 or 3, etc. Thus, by setting the ratio relationship between the maximum value and the minimum value of the interlayer spacing D, the risk of the central hole 240 collapsing due to the small interlayer gap near the central hole 240 or the small sum of all interlayer gaps near the central hole 240 can be further improved, and at the same time, the risk of the electrode assembly 200 performance deteriorating due to the large gap between the pole pieces causing the electrode assembly 200 to be wound less compactly can be alleviated.

[0070] In some embodiments, the interlayer spacing D is the gap between the main surfaces of two anode pole pieces 210 or two cathode pole pieces 220 facing each other in two adjacent circles. Within the first circle number range defined by the first predetermined circle number and the second predetermined circle number, the difference between the maximum and minimum values ​​of the interlayer spacing D in at least part of the region is greater than or equal to 5μm and less than or equal to 26μm. Among them, within the first circle number range, the difference between the maximum and minimum values ​​of the interlayer spacing D in at least part of the region can be between 5μm-10μm, or between 10μm-20μm, or between 20μm-26μm, etc. Specifically, the difference between the maximum and minimum values ​​can be 5μm, 8μm, 10μm, 15μm, 20μm, 24μm, or 26μm, etc. In this way, the risk of the center hole 240 collapsing due to the small interlayer gap near the center hole 240 or the small sum of all interlayer gaps near the center hole 240 can be further improved. At the same time, the risk of the performance of the electrode assembly 200 deteriorating due to the electrode assembly 200 not being wound compactly enough due to the large gap between the pole pieces can be alleviated.

[0071] In some embodiments, the head end 221 of the cathode electrode sheet 220 is located between two adjacent circles of the anode electrode sheet 210, and the head end 221 of the cathode electrode sheet 220 is located in at least a part of the area. The cathode electrode sheet 220 can be wound around the central axis of the center hole 240, and the head end 221 of the cathode electrode sheet 220 is the end of the cathode electrode sheet 220 that is closer to the center hole 240. The head end 221 of the anode electrode sheet 210 may be closer to the center hole 240 than the head end 221 of the cathode electrode sheet 220. It should be noted that the head end 221 of the cathode electrode sheet 220 is located in the cathode feed inlet area, and the pressure concentration of the battery cell 10 in the cathode feed inlet area is more obvious, so the risk of the center hole 240 collapsing near the head end 221 of the cathode electrode sheet 220 is higher. Therefore, the head end 221 of the cathode electrode sheet 220 is located between two adjacent circles of anode electrode sheets 210, and the head end 221 of the cathode electrode sheet 220 is located in at least a partial area, which can better improve the phenomenon of obvious pressure concentration at the cathode electrode sheet 220, further alleviate the risk of collapse of the center hole 240, and improve the reliability of the battery cell 10.

[0072] Combination Figure 5 , Figure 5 is a schematic diagram of a second cross-sectional structure of a battery cell according to one or more embodiments of the present application.

[0073] In some embodiments, at least a portion of the region is a local region P disposed along the circumference of the electrode assembly 200. At least a portion of the region is a portion of all regions disposed along the circumference of the electrode assembly 200, and the local region P may be of any shape, for example, the local region P may be a fan-shaped region, a rectangular region, a circular region, a triangular region, etc. Thus, the risk of the central hole 240 collapsing due to the small interlayer gap near the central hole 240 or the small sum of all interlayer gaps near the central hole 240 can be improved, and the risk of the electrode assembly 200 being not wound compactly enough due to the large gaps between the pole pieces over a large area can also be alleviated.

[0074] In some embodiments, the local area P is a fan-shaped area, and the central angle AA of the local area P is greater than or equal to 90 degrees. Specifically, the central angle AA of the fan-shaped area can be 90 degrees, 95 degrees, 100 degrees, 120 degrees, 180 degrees, 200 degrees or 240 degrees, etc. The head end 221 of the cathode electrode 220 is located in the fan-shaped area. Therefore, the central angle AA of the local area P is greater than or equal to 90 degrees, which can further improve the risk of the central hole 240 collapsing due to the small interlayer gap near the central hole 240 or the small sum of all interlayer gaps near the central hole 240.

[0075] In some embodiments, within the first number of turns defined by the first predetermined number of turns and the second predetermined number of turns, the interlayer spacing D outside the local area P is set to remain constant as the number of winding turns increases. Exemplarily, the first number of turns ranges from the first to the fifth turn, the local area P covers a portion of the first to the fifth turn, and the interlayer spacing D in other partial areas of the first to the fifth turn outside the local area P remains constant as the number of winding turns increases, for example, the interlayer spacing D between the first and second turns is the same as the interlayer spacing D between the second and third turns, the interlayer spacing D between the second and third turns is the same as the interlayer spacing D between the third and fourth turns, and so on. Thus, the interlayer spacing D outside the local area P is set to remain constant as the number of winding turns increases, which facilitates the manufacturing and forming of the electrode assembly 200, and alleviates the risk that the electrode assembly 200 is not wound compactly enough due to the large gap between most of the pole pieces of the electrode assembly 200, resulting in poor performance of the electrode assembly 200.

[0076] In some embodiments, within a second range of turns greater than the first range of turns defined by the first predetermined number of turns and the second predetermined number of turns, the interlayer spacing D of at least a portion of the region is set to remain constant or increase with the increase in the number of winding turns, and the number of winding turns within the second range of turns is greater than or equal to 1 / 4 of the total number of winding turns of the electrode assembly 200. The number of winding turns within the second range of turns may be greater than or equal to 1 / 3, 1 / 2, 2 / 3, 3 / 4, etc. of the total number of winding turns of the electrode assembly 200. Specifically, the number of winding turns within the second range of turns may be 1 / 3, 1 / 2, 2 / 3, 3 / 4, etc. of the total number of winding turns. In the second range of turns, the interlayer spacing D of at least part of the region is set to remain constant or increase with the increase of the number of winding turns. For example, the total number of winding turns can be ten turns, the first range of turns can include the first to fifth turns, the second range of turns includes the sixth to tenth turns, and the interlayer spacing D between the sixth and tenth turns can be the same or increase. The increasing trend can be a regular increasing trend or an irregular increasing trend, wherein the increasing trend can include but is not limited to linear increase and nonlinear increase. The number of winding turns within the second range of turns is greater than or equal to 1 / 4 of the total number of winding turns of the electrode assembly 200. For example, when the total number of winding turns is twenty turns, the number of winding turns within the second range of turns can be five turns, six turns, seven turns, eight turns, and the like. Therefore, the interlayer spacing D of at least part of the area within the second winding number range remains constant or shows an increasing trend as the winding number increases, which can alleviate the risk of poor performance of the electrode assembly 200 due to the large gap between the electrode sheets causing the electrode assembly 200 to be not wound compactly enough, thereby improving the structural stability of the battery cell 10.

[0077] In some embodiments, the ratio of the number of winding turns within the first range of turns to the number of winding turns within the second range of turns is between 1 / 3 and 2. Exemplarily, the ratio of the number of winding turns within the first range of turns to the number of winding turns within the second range of turns may be greater than or equal to 1 / 3 and less than or equal to 1, greater than or equal to 1 and less than or equal to 1.5, greater than or equal to 1.5 and less than or equal to 2, etc. Specifically, the ratio may be 1 / 3, 0.5, 0.8, 1, 1.5, 1.6, 1.8, 2, etc. Exemplarily, the number of winding turns within the first range of turns may be six turns, and the number of turns within the second range of turns may be eighteen turns, in which case the ratio of the number of winding turns within the first range of turns to the number of winding turns within the second range of turns is 1 / 3. Therefore, the ratio of the number of winding turns within the first range to the number of winding turns within the second range is between 1 / 3 and 2, which can improve the risk of collapse of the center hole 240 due to the small interlayer gap near the center hole 240 or the small sum of all interlayer gaps near the center hole 240. At the same time, it can also alleviate the risk of poor performance of the electrode assembly 200 due to the large gap between the pole pieces, which makes the electrode assembly 200 not wound compactly.

[0078] Combination Figure 6-Figure 9 , Figure 6 is a first schematic diagram of the interlayer spacing of a battery cell changing with the number of winding turns according to one or more embodiments of the present application; Figure 7 is a second schematic diagram of the interlayer spacing of a battery cell changing with the number of winding turns according to one or more embodiments of the present application; Figure 8 is a third schematic diagram showing the variation of the interlayer spacing of a battery cell with the number of winding turns according to one or more embodiments of the present application; Fig. 9 This is a fourth schematic diagram showing how the interlayer spacing of a battery cell varies with the number of winding turns according to one or more embodiments of the present application.

[0079] In some embodiments, within the range of the first number of turns defined by the first predetermined number of turns and the second predetermined number of turns, the interlayer spacing D of at least part of the area is set to decrease linearly or nonlinearly with the increase of the number of winding turns. Wherein, linear decrease may mean that the interlayer spacing D of at least part of the area gradually decreases at a fixed ratio or step size with the increase of the number of winding turns. It can be understood that, in this state, the interlayer spacing D of at least part of the area decreases uniformly with the increase of the number of winding turns. In the schematic diagram of the change of the interlayer spacing D with the number of winding turns, the linear decreasing trend can be represented by a straight line, and the slope of the straight line is a negative value. Furthermore, nonlinear decrease may include but is not limited to inverse proportional decrease, logarithmic decrease, exponential decrease, inverse trigonometric function decrease, etc. Figure 6-Figure 9As shown, trends 1 to 9 may represent some different changing trends of the interlayer spacing D as the number of winding turns increases. As a result, the interlayer spacing D of at least a portion of the area within the first number of turns decreases linearly or nonlinearly as the number of winding turns increases, which facilitates the manufacturing and forming of the electrode assembly 200 and improves the risk of the central hole 240 collapsing due to the increasing expansion force of the pole piece, thereby improving the reliability of the battery cell 10.

[0080] In some embodiments, within the first number of turns defined by the first predetermined number of turns and the second predetermined number of turns, the interlayer spacing D of at least part of the region is set to decrease in a step-by-step manner as the number of winding turns increases. Wherein, within the first number of turns, the interlayer spacing D can decrease layer by layer with a fixed difference. For example, the first predetermined number of turns is the first turn, the second predetermined number of turns is the fifteenth turn, the difference between the first interlayer spacing D between the first turn and the second turn and the second interlayer spacing D between the second turn and the third turn is the first difference, and the difference between the second interlayer spacing D and the third interlayer spacing D between the third turn and the fourth turn is the second difference, wherein the first difference and the second difference are equal, and so on, the first difference, the second difference to the thirteenth difference are all equal. Further, the first interlayer spacing D can be 36μm, the fourteenth interlayer spacing D can be 10μm, and the interlayer spacing D between the first turn to the fifteenth turn decreases layer by layer with a difference of 2μm. In some other embodiments, the step-by-step decrease can also be expressed as, within the first number of turns, two consecutive interlayer spacings D can be the same. For example, the first interlayer spacing D between the first turn and the second turn can be the same as the second interlayer spacing D between the second turn and the third turn, the third interlayer spacing D between the third turn and the fourth turn can be smaller than the second interlayer spacing D, and so on, the third interlayer spacing D is the same as the fourth interlayer spacing D, the fifth interlayer spacing D is smaller than the fourth interlayer spacing D, the sixth interlayer spacing D is equal to the fifth interlayer spacing D, and so on. It should be noted that the above examples do not limit the specific form of the step-by-step decrease, but are only used to illustrate that within the first number of turns, in the process where the interlayer spacing D decreases with the increase in the number of winding turns, there may be a situation where two consecutive interlayer spacings D are the same. It can be understood that there may also be a situation where three consecutive interlayer spacings D are the same, and there may be a situation where four, five or more consecutive interlayer spacings D are the same. Therefore, within the first range of turns, the interlayer spacing D of at least part of the area is set to decrease in a step-by-step manner as the number of winding turns increases, which facilitates the manufacturing and forming of the electrode assembly 200 and improves the risk of the center hole 240 collapsing due to the increasing expansion force of the pole piece, thereby improving the reliability of the battery cell 10.

[0081] Combination Fig.10 , Fig.10 It is a schematic flow chart of a method for preparing an electrode assembly according to one or more embodiments of the present application.

[0082] In order to solve the above problems, the present application also provides a method for preparing an electrode assembly, the preparation method comprising the following steps: Step S11: providing an anode electrode sheet 210 , a cathode electrode sheet 220 and a separator 230 .

[0083] The electrode assembly 200 is a component in the battery cell 10 where electrochemical reactions occur. The electrode assembly 200 is formed by winding the anode electrode sheet 210, the cathode electrode sheet 220 and the separator 230. The parts of the anode electrode sheet 210 and the cathode electrode sheet 220 with active materials constitute the main body of the electrode assembly 200, and the parts of the anode electrode sheet 210 and the cathode electrode sheet 220 without active materials each constitute the pole ear. The anode pole ear and the cathode pole ear can be located at one end of the main body or at both ends of the main body respectively. During the charge and discharge process of the battery, the anode active material and the cathode active material react with the electrolyte, and the pole ear connects the electrode terminal to form a current loop. During the charge and discharge process of the battery cell 10, active ions (such as lithium ions) are embedded and removed back and forth between the anode electrode sheet 210 and the cathode electrode sheet 220. The separator 230 is arranged between the anode electrode sheet 210 and the cathode electrode sheet 220, which can prevent the anode electrode sheet 210 and the cathode electrode sheet 220 from short-circuiting, and at the same time allow active ions to pass through.

[0084] Step S12: Winding the anode electrode sheet 210, the cathode electrode sheet 220 and the diaphragm 230 to form an electrode assembly 200 having a central hole 240 therein; wherein the interlayer spacing D in at least a portion of the area of ​​the electrode assembly 200 arranged along its circumference is arranged to show a decreasing trend starting from a first predetermined number of turns with the increase of the number of winding turns, and the decreasing trend ends after a second predetermined number of turns, the second predetermined number of turns is greater than the first predetermined number of turns, the first predetermined number of turns is arranged close to the central hole 240, and the number of winding turns within a first number of turns defined by the first predetermined number of turns and the second predetermined number of turns is greater than or equal to 1 / 4 of the total number of winding turns of the electrode assembly 200.

[0085] The first predetermined number of turns is set close to the center hole 240. For example, when the total number of winding turns is thirty turns, the first predetermined number of turns can be the first turn, the second turn, the third turn, the fifth turn, the sixth turn, etc. The interlayer spacing D in at least part of the area shows a decreasing trend with the increase of the number of winding turns from the first predetermined number of turns, and ends the decreasing trend after the second predetermined number of turns. For example, when the total number of winding turns is twenty turns, the first predetermined number of turns can be the first turn, the second predetermined number of turns can be the fifth turn, and the interlayer spacing D shows a decreasing trend between the first turn and the fifth turn, wherein the decreasing trend can be a regular decreasing trend or an irregular decreasing trend. It should be noted that due to the existence of tolerance, the decreasing trend is not limited to decreasing turn by turn. In actual products, after obtaining a series of interlayer spacings D, it can be judged whether multiple interlayer spacings D meet the overall decreasing trend by data fitting or local maximum value method.

[0086] Thus, the interlayer spacing D in at least a portion of the area of ​​the electrode assembly 200 arranged along its circumference shows a decreasing trend as the number of winding turns increases from the first predetermined number of turns, and the decreasing trend ends after the second predetermined number of turns, which can make the pole pieces away from the center hole 240 more compact, improve the overall product strength of the electrode assembly 200 after winding, and at the same time, the interlayer spacing D of at least a portion of the area of ​​the electrode assembly 200 near the center hole 240 is greater than the interlayer spacing D away from the center hole 240, thereby providing a larger buffer space for the expansion of the pole pieces near the center hole 240, thereby alleviating the risk of the center hole 240 collapsing due to the increasing expansion force of the pole pieces during the cycle aging process of the battery cell 10, thereby improving the reliability of the battery cell 10, and at the same time, by making the number of winding turns within the first number of turns greater than or equal to 1 / 4 of the total number of winding turns, the risk of the center hole 240 collapsing due to the small interlayer gap near the center hole 240 or the small sum of all interlayer gaps near the center hole 240 can be further improved, thereby improving the reliability of the battery cell 10.

[0087] In some embodiments, step S12 includes: setting at least one or a combination of the thickness of the phase change coating, the thickness of the polymer particle coating and the bump height in at least a partial area to show a decreasing trend as the number of winding turns increases; and / or, setting the winding tension in at least a partial area to show an increasing trend as the number of winding turns increases.

[0088] In some embodiments, a phase change coating of different thicknesses may be applied to the surface of the anode electrode piece 210, the cathode electrode piece 220 or the diaphragm 230 in at least a part of the area, and the material of the phase change coating may include but is not limited to paraffin, polyol, etc. The thickness of the phase change coating may be less than or equal to 36μm, greater than or equal to 12μm, and the thickness tolerance may be plus or minus 2μm. The thickness of the phase change coating in at least a part of the area is set to decrease with the increase of the number of winding turns. In some application scenarios, within the first number of turns, starting from the first predetermined number of turns, the thickness of the phase change coating decreases by a certain amount for each increase in the first preset number of turns. Among them, the first preset number of turns may be one to three turns. For example, starting from the first predetermined number of turns, the phase change coating may decrease by a certain thickness for each increase of two turns. Specifically, the thickness of each decrease may be between 0.6μm and 1μm. Further, the thickness of each decrease may be 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, and so on. This makes it easier to arrange the interlayer spacing D in at least a portion of the circumferential region of the electrode assembly 200 to decrease with the increase in the number of winding turns starting from the first predetermined number of turns and ending the decreasing trend after the second predetermined number of turns.

[0089] In some embodiments, the pressure of the convex roller can be adjusted to form convex points of different heights on the surface of the cathode electrode 220. The initial pressure value of the convex roller can be between 1.5MPa-2MPa, wherein the initial pressure value of the convex roller can be between 1.5MPa-1.8MPa, or 1.8MPa-2MPa, etc. Specifically, the initial pressure value can be 1.5MPa, 1.6MPa, 1.8MPa, 2MPa, etc. The pressure of the convex roller in at least part of the area is set to decrease with the increase of the number of winding turns. In some application scenarios, within the first number of turns, starting from the first predetermined number of turns, a certain convex roller pressure value is decreased for each increase of the second preset number of turns. Among them, the second preset number of turns can be one to five turns. For example, starting from the first predetermined number of turns, the convex roller can decrease a certain pressure for every increase of three turns. Specifically, the pressure decreased each time can be between 0.05MPa-0.1MPa. Further, the pressure of each decrease may be 0.05MPa, 0.06MPa, 0.07MPa, 0.08MPa or 0.1MPa, etc. In some application scenarios, the pressure applied by the convex point roller between the first predetermined number of turns and the second predetermined number of turns may be between 0.5MPa and 1MPa. This facilitates the interlayer spacing D in at least a portion of the region of the electrode assembly 200 arranged along its circumference to be arranged to decrease from the first predetermined number of turns as the number of winding turns increases, and the decreasing trend ends after the second predetermined number of turns.

[0090] In some embodiments, the winding tension of the anode electrode sheet 210, the cathode electrode sheet 220 and the diaphragm 230 for different winding turns in the winding process can be adjusted. The initial winding tension value of the winding process can be between 0.05MPa-0.5MPa, wherein the initial winding tension value can be between 0.05MPa-0.25MPa, or between 0.25MPa-0.5MPa, etc. Specifically, the initial winding tension value can be 0.05MPa, 0.1MPa, 0.25MPa, 0.4MPa or 0.5MPa, etc. The winding tension in at least part of the area is set to increase with the increase of the number of winding turns. In some application scenarios, within the first number of turns, starting from the first predetermined number of turns, a certain winding tension value is increased for each increase in the third preset number of turns. Among them, the third preset number of turns can be one to five turns. For example, starting from the first predetermined number of turns, every four turns increase, a certain winding tension value is increased. Specifically, the winding pressure value increased each time may be between 0.01 MPa and 0.1 MPa. Further, the winding pressure value increased each time may be 0.01 MPa, 0.02 MPa, 0.04 MPa, 0.06 MPa, 0.08 MPa, 0.09 MPa or 0.1 MPa, etc. In some application scenarios, between the first predetermined number of turns and the second predetermined number of turns, the winding tension value may be between 0.35 MPa and 3.5 MPa. Thereby, it is convenient to set the interlayer spacing D in at least a part of the area where the electrode assembly 200 is arranged along its circumferential direction to be arranged to decrease from the first predetermined number of turns with the increase of the number of winding turns, and end the decreasing trend after the second predetermined number of turns.

[0091] In some embodiments, the polymer particle coating layer may be coated with different weights on the surface of the diaphragm 230 to adjust the thickness of the polymer particle coating layer. The initial weight of the polymer particle coating layer may be between 5.25-7.5 mg / 1540.25 mm 2 The initial weight of the polymer particle coating may be between 5.25-6.5 mg / 1540.25 mm 2 Between, or between 6.5 -7.5mg / 1540.25mm 2 Specifically, the initial weight of the polymer particle coating can be 5.25 mg / 1540.25 mm 2 、6mg / 1540.25mm 2 、6.5 mg / 1540.25mm 2 、7mg / 1540.25mm 2 or 7.5 mg / 1540.25 mm 2Etc. The weight of the polymer particle coating in at least a part of the area is set to decrease with the increase of the number of winding turns. In some application scenarios, within the first number of turns, starting from the first predetermined number of turns, the weight of the polymer particle coating decreases by a certain amount with each increase of the fourth predetermined number of turns. The fourth predetermined number of turns may be one to five turns. For example, starting from the first predetermined number of turns, the weight of the polymer particle coating decreases by a certain amount with each increase of five turns. Specifically, the weight of the polymer particle coating decreased each time may be between 0.15-0.35 mg / 1540.25mm 2 Further, the weight of each decreasing polymer particle coating can be 0.15 mg / 1540.25 mm 2 , 0.18 mg / 1540.25 mm 2 , 0.2 mg / 1540.25 mm 2 , 0.25 mg / 1540.25 mm 2 , 0.3 mg / 1540.25 mm 2 or 0.35 mg / 1540.25 mm 2 In some application scenarios, between the first predetermined number of turns and the second predetermined number of turns, the weight of the polymer particle coating may be between 0.75 mg and 2 mg / 1540.25 mm 2 Thus, the interlayer spacing D in at least a part of the region of the electrode assembly 200 arranged along the circumferential direction thereof is arranged to be arranged to decrease with the increase of the number of winding turns from the first predetermined number of turns, and to end the decreasing trend after the second predetermined number of turns.

[0092] Therefore, by adjusting at least one or a combination of the thickness of the phase change coating, the thickness of the polymer particle coating, the bump height and the winding tension in at least part of the area, it is beneficial to set the interlayer spacing D in at least part of the area to show a decreasing trend as the number of winding turns increases from a first predetermined number of turns, and end the decreasing trend after a second predetermined number of turns. This can make the pole pieces away from the center hole 240 more compact, improve the overall product strength of the electrode assembly 200 after winding, and at the same time, make the interlayer spacing D of at least part of the area of ​​the electrode assembly 200 near the center hole 240 greater than the interlayer spacing D away from the center hole 240, thereby providing a larger buffer space for the expansion of the pole piece near the center hole 240, thereby alleviating the risk of the center hole 240 collapsing due to the increasing expansion force of the pole piece during the cycle aging process of the battery cell 10, and improving the reliability of the battery cell 10.

[0093] In some embodiments, step S12 includes: setting the thickness of the phase change coating in at least a part of the region to decrease with the increase of the number of windings. The preparation method further includes: after the winding is completed, changing the phase change coating from a solid state to a liquid state or a gas state.

[0094] It should be noted that the phase change coating has the ability to change physical state within a certain temperature range and has the characteristics of large volume change. When winding is completed, the phase change coating is solid and has a certain shape and rigidity. Through a high temperature formation process, the phase change coating can be converted from solid to liquid and gas, which is conducive to setting the interlayer spacing D in at least part of the area to decrease from the first predetermined number of turns as the number of winding turns increases, and the decreasing trend ends after the second predetermined number of turns. Therefore, by changing the phase change coating from solid to liquid or gas after winding, the thickness of the phase change coating in at least part of the area is adjusted, so that the interlayer spacing D in at least part of the area is set to show a decreasing trend with the increase of the winding number from a first predetermined number of turns, and the decreasing trend ends after the second predetermined number of turns. This can make the pole pieces away from the center hole 240 more compact, improve the overall product strength of the electrode assembly 200 after winding, and at the same time, it can also make the interlayer spacing D of at least part of the area of ​​the electrode assembly 200 near the center hole 240 greater than the interlayer spacing D away from the center hole 240, thereby providing a larger buffer space for the expansion of the pole piece near the center hole 240, thereby alleviating the risk of the center hole 240 collapsing due to the increasing expansion force of the pole piece during the cycle aging process of the battery cell 10, and improving the reliability of the battery cell 10.

[0095] In summary, the battery cell 10 provided in the present application includes a shell assembly 100 and an electrode assembly 200, the shell assembly 100 has a accommodating space 130; the electrode assembly 200 is arranged in the accommodating space 130; wherein, the electrode assembly 200 includes an anode electrode sheet 210, a cathode electrode sheet 220 and a diaphragm 230 for spacing the anode electrode sheet 210 and the cathode electrode sheet 220, the electrode assembly 200 is wound and a center hole 240 is formed inside the electrode assembly 200; wherein, the interlayer spacing D in at least a part of the area where the electrode assembly 200 is arranged along its circumference is arranged to show a decreasing trend starting from a first predetermined number of turns with the increase of the number of winding turns, and the decreasing trend ends after the second predetermined number of turns, and the first predetermined number of turns is arranged close to the center hole 240. Thus, the interlayer spacing D in at least a portion of the region of the electrode assembly 200 arranged along its circumference shows a decreasing trend as the number of winding turns increases from the first predetermined number of turns, and the decreasing trend ends after the second predetermined number of turns, which can make the pole pieces away from the center hole 240 more compact, improve the overall product strength of the electrode assembly 200 after winding, and at the same time, the interlayer spacing D of at least a portion of the region of the electrode assembly 200 near the center hole 240 is greater than the interlayer spacing D at a position away from the center hole 240, thereby providing a larger buffer space for the expansion of the pole piece near the center hole 240, thereby alleviating the risk of the center hole 240 collapsing due to the increasing expansion force of the pole piece during the cycle aging process of the battery cell 10, and improving the reliability of the battery cell 10. Compared with other types of battery cells, the battery cell 10 of the present application has a lower risk of collapse of the center hole 240 and a higher reliability.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: The battery cell comprises: The housing assembly has a receiving space; An electrode assembly is disposed in the accommodation space; The electrode assembly comprises an anode electrode sheet, a cathode electrode sheet and a separator for separating the anode electrode sheet and the cathode electrode sheet, the electrode assembly is wound and a central hole is formed inside the electrode assembly; Among them, the interlayer spacing in at least a partial area of ​​the electrode assembly arranged along its circumferential direction is arranged to show a decreasing trend starting from a first predetermined number of turns as the number of winding turns increases, and the decreasing trend ends after a second predetermined number of turns, the second predetermined number of turns is greater than the first predetermined number of turns, and the first predetermined number of turns is arranged close to the center hole.

2. The battery cell according to claim 1, characterized in that: The number of winding turns within a first range of turns defined by the first predetermined number of turns and the second predetermined number of turns is greater than or equal to 1 / 4 of the total number of winding turns of the electrode assembly.

3. The battery cell according to claim 2, characterized in that: The number of the winding turns within the first range of turns is less than or equal to 1 / 2 of the total number of winding turns.

4. The battery cell according to claim 1, characterized in that: The first predetermined number of turns is greater than or equal to 1 and less than or equal to 5.

5. The battery cell according to claim 1, characterized in that: The first predetermined number of turns is greater than 1, and the interlayer spacing from the innermost turn of the electrode assembly to the first predetermined number of turns remains constant or increases.

6. The battery cell according to any one of claims 1 to 4, characterized in that: The second predetermined number of turns is greater than or equal to 1 / 3 of the total number of turns of the electrode assembly and less than or equal to 1 / 2 of the total number of turns.

7. The battery cell according to any one of claims 2 to 4, characterized in that: Within a first range of turns defined by the first predetermined number of turns and the second predetermined number of turns, the interlayer spacing of at least a portion of the region is configured to decrease linearly or nonlinearly as the number of winding turns increases.

8. The battery cell according to any one of claims 2 to 4, characterized in that: Within a first range of turns defined by the first predetermined number of turns and the second predetermined number of turns, the interlayer spacing of at least a portion of the region is configured to decrease in a step-wise manner as the number of winding turns increases.

9. The battery cell according to claim 1, characterized in that: Within a first range of turns defined by the first predetermined number of turns and the second predetermined number of turns, a ratio of a maximum value to a minimum value of an interlayer spacing in at least a partial region is greater than or equal to 1.5 and less than or equal to 3.

10. The battery cell according to claim 1, characterized in that: The interlayer spacing is the gap between the main surfaces of the two anode plates or the two cathode plates of two adjacent circles facing each other. Within the first number of circles defined by the first predetermined number of circles and the second predetermined number of circles, the difference between the maximum and minimum values ​​of the interlayer spacing in at least part of the area is greater than or equal to 5μm and less than or equal to 26μm.

11. The battery cell according to claim 1, characterized in that: The head end of the cathode electrode piece is located between two adjacent circles of the anode electrode piece, and the head end of the cathode electrode piece is located in the at least partial area.

12. The battery cell according to claim 11, characterized in that: The at least partial area is a local area arranged along the circumference of the electrode assembly.

13. The battery cell according to claim 12, characterized in that: The local area is a fan-shaped area, and a central angle of the local area is greater than or equal to 90 degrees.

14. The battery cell according to claim 12, characterized in that: Within a first range of turns defined by the first predetermined number of turns and the second predetermined number of turns, the interlayer spacing outside the local area is configured to remain constant as the number of winding turns increases.

15. The battery cell according to claim 1, characterized in that: Within a second range of winding turns that is greater than the first range of winding turns defined by the first predetermined number of turns and the second predetermined number of turns, the interlayer spacing of at least a portion of the area is configured to remain constant or increase as the number of winding turns increases, and the number of winding turns within the second range of winding turns is greater than or equal to 1 / 4 of the total number of winding turns of the electrode assembly.

16. The battery cell according to claim 15, characterized in that: A ratio of the number of winding turns within the first range of turns to the number of winding turns within the second range of turns is between 1 / 3 and 2.

17. A battery device, characterized in that: The battery device comprises the battery cell according to any one of claims 1 to 16.

18. An electrical device, characterized in that: The electrical device comprises the battery device as claimed in claim 17.

19. A method for preparing an electrode assembly, characterized in that: The preparation method comprises: Providing anode plates, cathode plates and diaphragms; Winding the anode electrode sheet, the cathode electrode sheet and the separator to form an electrode assembly having a central hole therein; Among them, the interlayer spacing in at least a partial area of ​​the electrode assembly arranged along its circumferential direction is arranged to show a decreasing trend starting from a first predetermined number of turns with the increase of the winding number, and the decreasing trend ends after a second predetermined number of turns, the second predetermined number of turns is greater than the first predetermined number of turns, the first predetermined number of turns is arranged close to the center hole, and the number of winding turns within a first number range defined by the first predetermined number of turns and the second predetermined number of turns is greater than or equal to 1 / 4 of the total winding number of turns of the electrode assembly.

20. The preparation method according to claim 19, characterized in that: The winding operation of the anode electrode sheet, the cathode electrode sheet and the separator includes: At least one or a combination of the thickness of the phase change coating, the thickness of the polymer particle coating and the height of the protrusions in at least a portion of the region is set to decrease with the increase of the number of winding turns; And / or, the winding tension in at least a partial area is set to increase with the increase of the number of winding turns.

21. The preparation method according to claim 19, characterized in that: The winding operation of the anode electrode sheet, the cathode electrode sheet and the diaphragm comprises: The thickness of the phase change coating in at least a portion of the region is set to decrease with the increase of the number of winding turns; The preparation method further comprises: After the winding is completed, the phase change coating is changed from a solid state to a liquid state or a gas state.

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