Preparation method, hot pressing device, battery monomer, battery device and electric equipment

Abstract

The invention relates to the technical field of battery production, in particular to a preparation method, a hot pressing device, a battery monomer, a battery device and electric equipment. The preparation method comprises the steps that an electrode assembly is provided, the electrode assembly comprises a diaphragm, the electrode assembly is divided into multiple hot pressing areas in the first direction, the multiple hot pressing areas are subjected to hot pressing through different hot pressing parameters, and the porosity of the diaphragm is reduced from the middle position to the two sides in the first direction, the first direction is the height direction of the electrode assembly. According to the preparation method of the electrode assembly, the reaction rate of the electrode assembly in the middle position of the first direction can be reduced, so that the reaction rates of the electrode assembly in different positions of the first direction approach to be consistent, and the attenuation speed of the electrode assembly is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of battery production, and in particular to a preparation method, a hot pressing device, a battery cell, a battery device and an electrical device. Background Art

[0002] This section merely provides background information related to the present disclosure and is not necessarily prior art.

[0003] As new energy technologies become increasingly mature, new energy vehicles and other electrical equipment are gradually entering the public eye. The core technology of new energy vehicles lies in the battery device, and the safety and stability of the battery device directly determine the performance of the entire vehicle.

[0004] The battery device includes a battery cell, and the battery cell includes an electrode assembly. The middle part of the electrode assembly along the height direction is prone to the highest temperature due to the inability to effectively dissipate heat. This will cause the middle part of the electrode assembly to become the area with the fastest reaction rate and the highest capacity decay, resulting in inconsistent capacity decay at different positions of the electrode assembly and too rapid capacity decay of the electrode assembly. Summary of the invention

[0005] In view of the above problems, the present application provides a preparation method, a battery cell, a battery device and an electrical equipment, which solves the problem of excessive capacity decay of the electrode assembly caused by inconsistent capacity decay at different positions of the coating area of ​​the electrode piece in the prior art.

[0006] A first aspect of an embodiment of the present application provides a method for preparing an electrode assembly, the method comprising:

[0007] Providing an electrode assembly, the electrode assembly comprising a separator;

[0008] Dividing the electrode assembly into a plurality of hot pressing areas along a first direction;

[0009] The multiple hot pressing areas are hot pressed using different hot pressing parameters, so that the porosity of the diaphragm decreases from the middle position to both sides along the first direction; wherein the first direction is the height direction of the electrode assembly.

[0010] The preparation method of the electrode assembly of the embodiment of the present application provides an electrode assembly with a diaphragm, and divides the electrode assembly into multiple hot pressing areas along a first direction, and uses different hot pressing parameters to hot press the multiple hot pressing areas, so that the porosity of the diaphragms in the multiple hot pressing areas decreases from the middle position to both sides along the first direction. This can reduce the reaction rate of the middle position of the electrode assembly along the first direction, make the reaction rates of different positions of the electrode assembly along the first direction approach to the same, and reduce the attenuation rate of the electrode assembly.

[0011] In some embodiments of the present application, the multiple hot pressing regions include a first hot pressing region and a second hot pressing region, wherein the first hot pressing region is arranged in the middle position, and the second hot pressing regions are respectively arranged on opposite sides of the first hot pressing region along the first direction; wherein at least one hot pressing parameter of the first hot pressing region is greater than the corresponding hot pressing parameter of the second hot pressing region, so that the porosity of the diaphragm in the first hot pressing region is smaller than the porosity of the diaphragm in the second hot pressing region.

[0012] In an embodiment of the present application, a first hot pressing region and a second hot pressing region are set, wherein the first hot pressing region is set in the middle position, and the second hot pressing region is respectively set on the opposite sides of the first hot pressing region along the first direction; wherein at least one hot pressing parameter of the first hot pressing region is greater than the corresponding hot pressing parameter of the second hot pressing region, so that the porosity of the diaphragm in the first hot pressing region is smaller than the porosity of the diaphragm in the second hot pressing region, so that the reaction rates of the first hot pressing region and the second hot pressing region can be made close to the same, thereby reducing the attenuation rate of the electrode assembly.

[0013] In some embodiments of the present application, the multiple hot pressing regions include a third hot pressing region, the third hot pressing region is provided on the side of the second hot pressing region away from the first hot pressing region, and at least one hot pressing parameter of the second hot pressing region is greater than the corresponding hot pressing parameter of the third hot pressing region.

[0014] In the embodiment of the present application, a third hot pressing region is provided on the side of the second hot pressing region away from the first hot pressing region, and at least one hot pressing parameter of the third hot pressing region is smaller than the corresponding hot pressing parameter of the second hot pressing region. The reaction rates of the second hot pressing region and the third hot pressing region can be made close to the same, thereby reducing the attenuation rate of the electrode assembly.

[0015] In some embodiments of the present application, before hot pressing multiple hot pressing regions using different hot pressing parameters, the preparation method also includes obtaining the operating parameter distribution of the electrode assembly; dividing the multiple hot pressing regions according to the operating parameter distribution, and determining the hot pressing parameters of each hot pressing region.

[0016] The embodiments of the present application obtain the operating parameter distribution of the electrode assembly; divide the multiple hot pressing areas according to the operating parameter distribution, and determine the hot pressing parameters of each hot pressing area. Then, different hot pressing areas can have different porosities according to the hot pressing parameters of different hot pressing areas, so that the reaction rate of the electrode assembly is more balanced and more consistent, thereby reducing the capacity attenuation of the electrode assembly.

[0017] In some embodiments of the present application, the operating parameter distribution includes the temperature distribution of the electrode assembly and the capacity reduction of the electrode assembly; dividing a plurality of hot pressing regions according to the operating parameter distribution, and determining the hot pressing parameters of each hot pressing region specifically includes: dividing a plurality of hot pressing regions according to the temperature distribution of the electrode assembly; determining the hot pressing parameters of each hot pressing region according to the capacity reduction of the electrode assembly in each hot pressing region.

[0018] The embodiments of the present application divide the electrode assembly into a plurality of hot pressing zones according to the temperature distribution, and determine the hot pressing parameters of each hot pressing zone according to the capacity reduction of the electrode assembly in each hot pressing zone. Then, the electrode assembly can be divided into a plurality of hot pressing zones according to the temperature distribution, and the hot pressing parameters of each hot pressing zone can be determined according to the capacity reduction of the electrode assembly in each hot pressing zone, so that each hot pressing zone can be hot pressed according to different hot pressing parameters, thereby achieving control of the porosity of each hot pressing zone, so that the reaction rate of each hot pressing zone is more balanced.

[0019] In some embodiments of the present application, determining the hot pressing parameters of each hot pressing region based on the capacity reduction of the electrode assembly in each hot pressing region specifically includes determining the hot pressing region with the smallest capacity reduction of the electrode assembly as a reference hot pressing region; and adjusting the hot pressing parameters of other hot pressing regions based on the hot pressing parameters of the reference hot pressing region.

[0020] The embodiments of the present application determine the hot pressing area where the capacity reduction of the electrode assembly is the smallest as the reference hot pressing area; and adjust the hot pressing parameters of other hot pressing areas according to the hot pressing parameters of the reference hot pressing area. Then, the hot pressing parameters of other hot pressing areas can be specifically adjusted according to the hot pressing parameters of the reference hot pressing area, thereby achieving accurate control of the porosity of each hot pressing area.

[0021] In some embodiments of the present application, adjusting the hot pressing parameters of other hot pressing areas according to the hot pressing parameters of the reference hot pressing area specifically includes adjusting at least one hot pressing parameter of the other hot pressing areas according to the difference between the capacity reduction of the electrode assemblies in the other hot pressing areas and the capacity reduction of the electrode assemblies in the reference hot pressing area.

[0022] The embodiments of the present application adjust at least one hot pressing parameter of other hot pressing areas according to the difference between the capacity reduction of the electrode assemblies in other hot pressing areas and the capacity reduction of the electrode assemblies in the reference hot pressing area, so that the hot pressing parameters of other hot pressing areas can be adjusted more accurately, thereby achieving accurate control of the porosity of each hot pressing area.

[0023] In some embodiments of the present application, the hot pressing parameters include hot pressing temperature and hot pressing time.

[0024] In the embodiments of the present application, by setting the hot pressing temperature and the hot pressing time, the porosity of each hot pressing area can be accurately controlled by adjusting at least one of the hot pressing temperature and the hot pressing time.

[0025] In some embodiments of the present application, before hot pressing a plurality of hot pressing regions using different hot pressing parameters, the preparation method further includes preparing an electrode assembly and fixing the electrode assembly on a hot pressing device.

[0026] The embodiments of the present application prepare an electrode assembly and fix the electrode assembly on a hot pressing device, which can facilitate hot pressing of multiple hot pressing areas of the electrode assembly, thereby improving the efficiency of the preparation method of the electrode assembly.

[0027] A second aspect of the embodiments of the present application provides a hot pressing device, which is used to implement the method for preparing the electrode assembly mentioned in the above embodiments.

[0028] The embodiments of the present application use a hot pressing device and the electrode assembly preparation method mentioned in the above embodiments, so that the porosity of the diaphragm in multiple hot pressing areas can be reduced from the middle position to both sides along the first direction, thereby reducing the reaction rate of the electrode assembly in the middle position along the first direction, making the reaction rates of the electrode assembly at different positions along the first direction approach to the same, thereby reducing the attenuation rate of the electrode assembly.

[0029] In some embodiments of the present application, the hot pressing device includes a first pressing plate and a second pressing plate that are relatively spaced apart, a driving member and a heating member, and an installation space for placing an electrode assembly is formed between the first pressing plate and the second pressing plate; the driving member is transmission-connected to at least one of the first pressing plate and the second pressing plate, so that the first pressing plate and the second pressing plate are closer to or farther away from each other; wherein the heating member is thermally conductively connected to the first pressing plate and the second pressing plate, respectively.

[0030] The embodiments of the present application are provided with a first pressing plate and a second pressing plate which are relatively spaced apart, and a driving member and a heating member, wherein an installation space for placing an electrode assembly is formed between the first pressing plate and the second pressing plate; the driving member is transmission-connected to at least one of the first pressing plate and the second pressing plate, so that the first pressing plate and the second pressing plate are closer to or farther away from each other; wherein the heating member is thermally conductively connected to the first pressing plate and the second pressing plate, respectively, so that the electrode assembly can be heated by the heating member, and the electrode assembly can be pressurized by the first pressing plate and the second pressing plate at the same time, thereby realizing hot pressing of the electrode assembly.

[0031] In some embodiments of the present application, the first pressure plate includes multiple independent first sub-pressure plates, each of which is respectively arranged corresponding to a hot pressing area; and / or the second pressure plate includes multiple independent second sub-pressure plates, each of which is respectively arranged corresponding to a first sub-pressure plate.

[0032] In an embodiment of the present application, the first pressing plate includes a plurality of independent first sub-pressing plates, and each first sub-pressing plate is respectively arranged corresponding to a hot pressing area; the second pressing plate includes a plurality of independent second sub-pressing plates, and each second sub-pressing plate is respectively arranged corresponding to the first sub-pressing plate. Then, hot pressing of a hot pressing area can be achieved by respectively using a first sub-pressing plate and the corresponding second sub-pressing plate, thereby achieving separate hot pressing of multiple hot pressing areas of the electrode assembly.

[0033] A third aspect of the embodiments of the present application provides a battery cell, which includes an electrode assembly manufactured by the method for preparing the electrode assembly mentioned in the above embodiments.

[0034] A fourth aspect of the embodiments of the present application provides a battery device, including a battery box and a battery cell as mentioned in the above embodiments, wherein the battery cell is disposed in the battery box.

[0035] A fifth aspect of the embodiments of the present application provides an electrical device, which includes the battery device mentioned in the above implementation, and the battery device is used to store or provide electrical energy.

[0036] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0038] Figure 1 A schematic diagram of the structure of an electrical device provided in some embodiments of the present application;

[0039] Figure 2 A schematic diagram of the structure of a battery device provided in some embodiments of the present application;

[0040] Figure 3 A schematic diagram of the structure of a battery cell provided in some embodiments of the present application;

[0041] Figure 4 A schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application;

[0042] Figure 5 A schematic diagram of the main structure of an electrode assembly provided in some embodiments of the present application;

[0043] Figure 6 for Figure 5 A schematic structural diagram of the electrode assembly shown in FIG. 1 at a second viewing angle;

[0044] Figure 7 for Figure 5 The electrode assembly shown in FIG. is a schematic structural diagram at a third viewing angle;

[0045] Figure 8 A schematic diagram of the structure of the hot pressing device provided in the embodiment of the present application in a working state;

[0046] Fig. 9 A flow chart of a method for preparing an electrode assembly provided in some embodiments of the present application.

[0047] The reference numerals are as follows:

[0048] 100, battery device; 200, electrical equipment; 300, controller; 400, motor;

[0049] 10. Battery cell; 11. Electrode assembly; 111. Positive electrode sheet; 112. Negative electrode sheet; 113. Diaphragm; 114. Tab; 115. Hot pressing area; 1151. First hot pressing area; 1152. Second hot pressing area; 1153. Third hot pressing area; 1154. Fourth hot pressing area; 1155. Fifth hot pressing area; 12. Shell; 121. Shell body; 122. End cover;

[0050] 20. Battery box; 21. First box; 22. Second box; 23. Accommodation space;

[0051] 500, hot pressing device; 501, first pressing plate; 5011, first sub-pressing plate; 502, second pressing plate; 5021, second sub-pressing plate; 503, installation space; 504, driving member; 505, heating member; 5051, heating plate; 506, temperature controller; 507, pressure controller; 508, display and operation console;

[0052] XX, height direction;

[0053] YY, length direction. DETAILED DESCRIPTION

[0054] The following embodiments of the technical solution of the present application will be 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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).

[0060] 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" and "circumferential" etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and 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.

[0061] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected" and "fixed" 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 ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0062] At present, from the perspective of market development, the application of battery devices is becoming more and more extensive. Battery devices are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of battery devices, the market demand is also constantly expanding.

[0063] The battery device involved in the embodiment of the present application can be used in, but not limited to, electrical equipment such as vehicles, ships or aircraft. The battery device comprising the battery cells, battery devices, etc. involved in the present application can be used.

[0064] In the embodiments of the present application, the electrical equipment using the battery device as the power source may be, but is not limited to, mobile phones, tablets, laptop computers, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. Among them, the 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 the spacecraft may include airplanes, rockets, space shuttles, and spacecraft, etc.

[0065] It should be understood that the technical solutions described in the embodiments of the present application are not limited to the battery devices and electrical equipment described above, but can also be applied to all batteries including a box and electrical equipment using the battery.

[0066] The battery apparatus mentioned in the embodiments of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include multiple battery cells, which are connected in series, in parallel or in mixed connection through a busbar component.

[0067] In some embodiments, a battery cell assembly is generally formed by arranging a plurality of battery cells.

[0068] As an example, the battery cell assembly may be a battery module, which is formed by arranging and fixing a plurality of battery cells to form an independent module. As an example, the battery module may be formed by bundling a plurality of battery cells by a cable tie.

[0069] In some embodiments, the battery device may be a battery pack, which includes a case and one or more battery cell assemblies, wherein the battery cell assemblies are accommodated in the case.

[0070] As an example, the battery cell assembly may be a battery module, and the battery cell assembly may be accommodated in the box by fixing the battery module in the box.

[0071] As an example, the battery cell assembly may also be housed in the case by directly fixing a plurality of battery cells to the case.

[0072] As an example, the box may include a first box and a second box. The first box and the second box are buckled together to form a closed space inside the box to accommodate the battery cell assembly. The closed here means covered or closed, which can be sealed or unsealed. The first box can be a top cover or a bottom plate.

[0073] As an example, the box body may include a top cover, a frame and a bottom plate. The top cover and the bottom plate are respectively connected to the frame, so that a closed space is formed inside the box body to accommodate the battery cell assembly.

[0074] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0075] The battery cell includes an electrode assembly and an electrolyte. The electrode assembly is composed of a positive electrode sheet, a negative electrode sheet and a separator. The battery cell mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector. The current collector not coated with the positive active material layer protrudes from the current collector coated with the positive active material layer. The current collector not coated with the positive active material layer is stacked as a positive electrode tab. Taking lithium-ion batteries as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide. The negative electrode sheet includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector. The current collector not coated with the negative active material layer protrudes from the current collector coated with the negative active material layer. The current collector not coated with the negative active material layer is stacked as a negative electrode tab. The negative electrode current collector may be made of copper, and the negative electrode active material may be carbon or silicon, etc. The material of the separator may be PP (polypropylene) or PE (polyethylene), etc. In addition, the electrode assembly may be a winding structure or a laminated structure, but the embodiments of the present application are not limited thereto.

[0076] The technical solutions described in the embodiments of the present application are applicable to various electrical devices that use battery cells, such as mobile phones, portable devices, laptop computers, electric vehicles, electric toys, electric tools, vehicles, ships and spacecraft, for example, spacecraft include airplanes, rockets, space shuttles and spacecraft, etc.

[0077] The battery device includes a battery cell, and the battery cell includes an electrode assembly. The middle part of the electrode assembly along the height direction is prone to the highest temperature due to the inability to effectively dissipate heat. This will cause the middle part of the electrode assembly to become the area with the fastest reaction rate and the highest capacity decay, resulting in inconsistent capacity decay at different positions of the electrode assembly and too rapid capacity decay of the electrode assembly.

[0078] In order to solve this problem, the embodiment of the present application proposes a method for preparing an electrode assembly, the preparation method comprising providing an electrode assembly, the electrode assembly comprising a diaphragm; dividing the electrode assembly into a plurality of hot pressing regions along a first direction; and hot pressing the plurality of hot pressing regions using different hot pressing parameters, respectively, so that the porosity of the diaphragm decreases from the middle position to both sides along the first direction; wherein the first direction is the height direction of the electrode assembly. The method for preparing an electrode assembly of the embodiment of the present application, by providing an electrode assembly having a diaphragm, dividing the electrode assembly into a plurality of hot pressing regions along a first direction, and hot pressing the plurality of hot pressing regions using different hot pressing parameters, respectively, so that the porosity of the diaphragm decreases from the middle position to both sides along the first direction, can reduce the reaction rate of the electrode assembly at the middle position along the first direction, make the reaction rates of the electrode assembly at different positions along the first direction approach to be consistent, and reduce the attenuation rate of the electrode assembly.

[0079] The method for preparing the electrode assembly in the embodiment of the present application can be used in the production process of the battery.

[0080] The structure in the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0081] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0082] Combined with Figure 1 As shown, the vehicle 200 can be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery device 100 is arranged inside the vehicle 200, and the battery device 100 can be arranged at the bottom, head or tail of the vehicle 200. The battery device 100 can be used to power the vehicle 200, for example, the battery device 100 can be used as an operating power source for the vehicle 200. The vehicle 200 may also include a controller 300 and a motor 400, and the controller 300 is used to control the battery device 100 to power the motor 400, for example, for the starting, navigation and driving power requirements of the vehicle 200.

[0083] In some embodiments of the present application, the battery device 100 can not only serve as an operating power source for the vehicle 200, but also serve as a driving power source for the vehicle 200, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 200.

[0084] Combined with Figure 2 As shown, the embodiment of the present application provides a battery device 100, which can be a secondary battery or a primary battery, or a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 10 and the battery device 100 can be cylindrical, flat, rectangular, or in other shapes.

[0085] The battery device 100 (Battery Apparatus) mentioned in the embodiment of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly (Battery Cell Assembly) may include a plurality of battery cells 10, and the plurality of battery cells 10 are connected in series, in parallel or in mixed connection through a busbar component.

[0086] In some embodiments, a battery cell assembly is generally formed by arranging a plurality of battery cells 10; as an example, the battery cell assembly may be a battery module, which is formed by arranging and fixing a plurality of battery cells 10 to form an independent module. As an example, a battery module may be formed by bundling a plurality of battery cells 10 by a cable tie.

[0087] In some embodiments, the battery device 100 may be a battery pack, which includes a battery case 20 and one or more battery cell assemblies, wherein the battery cell assemblies are accommodated in the battery case 20 .

[0088] As an example, the battery cell assembly may be a battery module, and the battery cell assembly may be accommodated in the battery case 20 by fixing the battery module in the battery case 20 .

[0089] As an example, the battery cell assembly may also be accommodated in the battery case 20 by directly fixing the plurality of battery cells 10 to the battery case 20 .

[0090] The battery case 20 is used to provide a storage space 23 for the battery cell 10, and the battery case 20 can adopt a variety of structures. In some embodiments, the battery case 20 may include a first case 21 and a second case 22, the first case 21 and the second case 22 cover each other, and the first case 21 and the second case 22 jointly define a storage space 23 for accommodating the battery cell 10.

[0091] As an example, the battery box 20 can be a part of the chassis structure of the vehicle 200. For example, the battery box 20 can become at least a part of the floor of the vehicle 200, or the frame of the battery box 20 can become at least a part of the cross beam and longitudinal beam of the vehicle 200.

[0092] Combined with Figure 4 and Figure 5 As shown, an embodiment of the present application further provides a battery cell 10 , which includes an electrode assembly 11 and a separator 113 . The electrode assembly 11 includes a negative electrode sheet 112 and a positive electrode sheet 111 . Both the positive electrode sheet 111 and the negative electrode sheet 112 are provided with a tab 114 .

[0093] In some embodiments, the battery cell 10 also includes a shell 12 and an adapter (not shown in the figure), the shell 12 includes a shell body 121 and an end cover 122, the shell body 121 is an open structure at the upper end, the electrode assembly 11 is installed in 12, the end cover 122 is covered on the shell body 121, and is connected to the pole ear 114 of the electrode assembly 11 through the adapter.

[0094] like Fig. 9 As shown, the embodiment of the present application also proposes a method for preparing an electrode assembly 11, and the preparation method includes:

[0095] S91, providing an electrode assembly 11, wherein the electrode assembly 11 includes a separator 113;

[0096] S92, dividing the electrode assembly 11 into a plurality of hot pressing regions 115 along a first direction;

[0097] S93, hot pressing the multiple hot pressing areas 115 using different hot pressing parameters, so that the porosity of the diaphragm 113 decreases from the middle position to both sides along the first direction; wherein the first direction is the height direction of the electrode assembly 11.

[0098] like Figures 5 to 8 As shown, in S91, the positive electrode sheet 111, the separator 113 and the negative electrode sheet 112 are stacked or wound to form an electrode assembly 11;

[0099] In S92, the electrode assembly 11 is divided into a plurality of hot pressing regions 115 along a first direction, wherein the first direction is Figure 5 The XX direction is the XX direction, and the YY direction is the length direction of the electrode assembly 11. The hot pressing parameters of each hot pressing area 115 may be inconsistent, wherein the hot pressing parameters include hot pressing temperature and hot pressing pressure, and the hot pressing temperature of each hot pressing area 115 may be the same, and the hot pressing pressure is different; alternatively, the hot pressing temperature of each hot pressing area 115 may be different, and the hot pressing pressure is the same.

[0100] In S93, the porosity of the diaphragm 113 of the multiple hot pressing areas 115 decreases from the middle position to both sides along the first direction, which can be controlled by controlling the hot pressing temperature and / or hot pressing pressure of each hot pressing area 115, which will be described in more detail later.

[0101] The preparation method of the electrode assembly 11 of the embodiment of the present application provides an electrode assembly 11 having a diaphragm 113, and divides the electrode assembly 11 into multiple hot pressing areas 115 along a first direction, and uses different hot pressing parameters to hot press the multiple hot pressing areas 115, so that the porosity of the diaphragm 113 in the multiple hot pressing areas 115 decreases from the middle position to both sides along the first direction. This can reduce the reaction rate of the electrode assembly 11 at the middle position along the first direction, make the reaction rates of different positions of the electrode assembly 11 along the first direction approach to the same, and reduce the attenuation rate of the electrode assembly 11.

[0102] In some embodiments of the present application, Figure 5 and Figure 8 As shown, the multiple hot pressing areas 115 include a first hot pressing area 1151 and a second hot pressing area 1152, wherein the first hot pressing area 1151 is arranged in the middle position, and the second hot pressing areas 1152 are respectively arranged on the opposite sides of the first hot pressing area 1151 along the first direction; wherein at least one hot pressing parameter of the first hot pressing area 1151 is greater than the corresponding hot pressing parameter of the second hot pressing area 1152, so that the porosity of the diaphragm 113 of the first hot pressing area 1151 is smaller than the porosity of the diaphragm 113 of the second hot pressing area 1152.

[0103] As mentioned earlier, the hot pressing parameters include hot pressing temperature and hot pressing pressure. Here, at least one hot pressing parameter of the first hot pressing area 1151 is greater than the corresponding hot pressing parameter of the second hot pressing area 1152. The hot pressing temperature of the first hot pressing area 1151 can be greater than the hot pressing temperature of the second hot pressing area 1152, or the hot pressing pressure of the first hot pressing area 1151 can be greater than the hot pressing pressure of the second hot pressing area 1152. Both of these can make the porosity of the diaphragm 113 in the first hot pressing area 1151 smaller than the porosity of the diaphragm 113 in the second hot pressing area 1152.

[0104] In an embodiment of the present application, a first hot pressing region 1151 and a second hot pressing region 1152 are set, wherein the first hot pressing region 1151 is set in the middle position, and the second hot pressing regions 1152 are respectively set on opposite sides of the first hot pressing region 1151 along the first direction; wherein at least one hot pressing parameter of the first hot pressing region 1151 is greater than the corresponding hot pressing parameter of the second hot pressing region 1152, so that the porosity of the diaphragm 113 of the first hot pressing region 1151 is smaller than the porosity of the diaphragm 113 of the second hot pressing region 1152, so that the reaction rates of the first hot pressing region 1151 and the second hot pressing region 1152 can be made close to the same, thereby reducing the attenuation rate of the electrode assembly 11.

[0105] In some embodiments of the present application, Figure 5 and Figure 8As shown, the multiple hot pressing areas 115 include a third hot pressing area 1153 , and the third hot pressing area 1153 is provided on the side of the second hot pressing area 1152 away from the first hot pressing area 1151 , and at least one hot pressing parameter of the second hot pressing area 1152 is greater than the corresponding hot pressing parameter of the third hot pressing area 1153 .

[0106] Here, at least one hot pressing parameter of the second hot pressing area 1152 is greater than the corresponding hot pressing parameter of the third hot pressing area 1153. The hot pressing temperature of the second hot pressing area 1152 may be greater than the hot pressing temperature of the third hot pressing area 1153, or the hot pressing pressure of the second hot pressing area 1152 may be greater than the hot pressing pressure of the third hot pressing area 1153. Both of these can make the porosity of the diaphragm 113 of the second hot pressing area 1152 smaller than the porosity of the diaphragm 113 of the third hot pressing area 1153, thereby reducing the reaction rate of the second hot pressing area 1152, so that the reaction rate of the second hot pressing area 1152 and the reaction rate of the third hot pressing area 1153 are closer or more consistent.

[0107] In the embodiment of the present application, a third hot pressing region 1153 is provided on the side of the second hot pressing region 1152 away from the first hot pressing region 1151, and at least one hot pressing parameter of the third hot pressing region 1153 is smaller than the corresponding hot pressing parameter of the second hot pressing region 1152. The reaction rates of the second hot pressing region 1152 and the third hot pressing region 1153 can be made close to each other, thereby reducing the attenuation rate of the electrode assembly 11.

[0108] Optionally, before hot pressing the multiple hot pressing areas 115 using different hot pressing parameters, the preparation method also includes obtaining the operating parameter distribution of the electrode assembly 11; dividing the multiple hot pressing areas 115 according to the operating parameter distribution, and determining the hot pressing parameters of each hot pressing area 115.

[0109] The operating parameter distribution of the electrode assembly 11 here is the basis for dividing the multiple hot pressing areas 115, and can be set at certain intervals. Specifically, the operating parameter distribution includes the temperature distribution of the electrode assembly 11 and the capacity reduction of the electrode assembly 11, wherein the multiple hot pressing areas 115 can be divided according to temperature, for example, the temperature is greater than or equal to 55 degrees and less than 60 degrees for the first hot pressing area 1151, and the temperature is greater than or equal to 48 degrees and less than 55 degrees for the second hot pressing area 1152.

[0110] Optionally, the capacity reduction specifically includes obtaining a difference between an initial capacity of the electrode assembly 11 and a residual capacity of the electrode assembly 11 to determine the capacity reduction of the electrode assembly 11 .

[0111] The initial capacity of the electrode assembly 11 can be replaced by the theoretical capacity, and the residual capacity of the electrode assembly 11 can be obtained by a discharge test. Specifically, the battery cell 10 can be disassembled to obtain the disassembled electrode pieces, and then the electrode pieces can be made into button batteries to achieve detection. The button battery here is also called a button battery, which refers to a battery with an appearance like a small button, generally with a larger diameter and a thinner thickness.

[0112] The specific process of the discharge test includes the following steps:

[0113] Disassemble the battery cell 10 to obtain the disassembled electrode piece;

[0114] Soak the disassembled electrode in dimethyl carbonate for 3 to 5 minutes to remove surface impurities, then wipe off the active material on one side, leaving only the active material on the other side;

[0115] Cut the electrode into 5 to 10 discs, and select 5 discs with qualified weight;

[0116] Place the qualified disc into the positive side of the buckle battery housing with a gasket placed in advance, with the coated surface facing away from the positive electrode. Then drip 1-2 drops of electrolyte on the positive electrode sheet 111111, then place the diaphragm 113113 and drip 1-2 drops of electrolyte, then place the lithium sheet, gasket and shrapnel, and finally place the buckle battery negative side housing, and seal it with a sealing machine after assembling.

[0117] The active material content is calculated based on the weighed weight of the small disc, and the charge and discharge current required for charging and discharging is calculated based on the estimated gram capacity of the active material to conduct a charge and discharge test.

[0118] The embodiment of the present application obtains the operating parameter distribution of the electrode assembly 11; divides the multiple hot pressing areas 115 according to the operating parameter distribution, and determines the hot pressing parameters of each hot pressing area 115. Then, according to the hot pressing parameters of different hot pressing areas 115, different hot pressing areas 115 can have different porosities, so that the reaction rate of the electrode assembly 11 is more balanced and more consistent, thereby reducing the capacity attenuation of the electrode assembly 11.

[0119] Optionally, dividing the multiple hot pressing areas 115 according to the operating parameter distribution, and determining the hot pressing parameters of each hot pressing area 115 specifically includes: dividing the multiple hot pressing areas 115 according to the temperature distribution of the electrode assembly 11, and determining the hot pressing parameters of each hot pressing area 115 according to the capacity reduction of the electrode assembly 11 in each hot pressing area 115.

[0120] Considering that the capacity reduction of the electrode assembly 11 in each hot pressing zone 115 is different, the hot pressing parameters of each hot pressing zone 115 need to be different. Considering that the first hot pressing zone 1151 is located in the middle position, the hot pressing pressure of the first hot pressing zone 1151 is the largest, or the hot pressing temperature of the first hot pressing zone 1151 is the highest, the hot pressing pressure of the second hot pressing zone 1152 is located between the first hot pressing zone 1151 and the third hot pressing zone 1153, and the hot pressing temperature of the second hot pressing zone 1152 is located between the first hot pressing zone 1151 and the third hot pressing zone 1153.

[0121] The embodiment of the present application divides the electrode assembly 11 into a plurality of hot pressing areas 115 according to the temperature distribution, and determines the hot pressing parameters of each hot pressing area 115 according to the capacity reduction of the electrode assembly 11 in each hot pressing area 115. Then, the electrode assembly 11 can be divided into a plurality of hot pressing areas 115 according to the temperature distribution, and the hot pressing parameters of each hot pressing area 115 can be determined according to the capacity reduction of the electrode assembly 11 in each hot pressing area 115, so that each hot pressing area 115 can be hot pressed according to different hot pressing parameters, thereby achieving control of the porosity of each hot pressing area 115, so that the reaction rate of each hot pressing area 115 is more balanced.

[0122] Alternatively, if Figure 5 and Figure 8 As shown, the hot pressing area 115 is also provided with a fourth hot pressing area 1154 and a fifth hot pressing area 1155, wherein the fourth hot pressing area 1154 is provided on the side of the third hot pressing area 1153 away from the first hot pressing area 1151, and at least one hot pressing parameter of the third hot pressing area 1153 is greater than the corresponding hot pressing parameter of the fourth hot pressing area 1154. The fifth hot pressing area 1155 is provided on the side of the fourth hot pressing area 1154 away from the first hot pressing area 1151. Among them, the fifth hot pressing area 1155 is the area with the closest average temperature among the five hot pressing areas 115, therefore, the capacity reduction of the electrode assembly 11 in the fifth hot pressing area 1155 is the lowest, therefore, among the five areas, the porosity of the diaphragm 113 in the fifth hot pressing area 1155 can be the highest.

[0123] Correspondingly, the hot pressing area 115 may also be provided with a sixth hot pressing area 115 and a seventh hot pressing area 115 , etc., which are not listed here.

[0124] In some embodiments of the present application, determining the hot pressing parameters of each hot pressing area 115 according to the capacity reduction of the electrode assembly 11 in each hot pressing area 115 specifically includes determining the hot pressing area 115 with the smallest capacity reduction of the electrode assembly 11 as a reference hot pressing area; and adjusting the hot pressing parameters of other hot pressing areas 115 according to the hot pressing parameters of the reference hot pressing area.

[0125] Here, the hot pressing area 115 is divided into five for illustration. At this time, the area with the smallest capacity reduction of the electrode assembly 11 is the fifth hot pressing area 1155, that is, the reference hot pressing area. In this embodiment, the hot pressing temperature of the fifth hot pressing area 1155 is 80 degrees Celsius, and the hot pressing pressure is 6MPa. Correspondingly, the capacity reduction of the electrode assembly 11 in the fourth hot pressing area 1154 will be greater than the capacity reduction of the electrode assembly 11 in the fifth hot pressing area 1155. At this time, the hot pressing temperature of the fourth hot pressing area 1154 can be set to 80 degrees Celsius and the hot pressing pressure is 10MPa, the hot pressing temperature of the third hot pressing area 1153 is 80 degrees Celsius and the hot pressing pressure is 12MPa, the hot pressing temperature of the second hot pressing area 1152 is 80 degrees Celsius and the hot pressing pressure is 15MPa, and the hot pressing temperature of the first hot pressing area 1151 is 80 degrees Celsius and the hot pressing pressure is 20MPa.

[0126] In the embodiment of the present application, the hot pressing area 115 where the capacity reduction of the electrode assembly 11 is the smallest is determined as the reference hot pressing area; the hot pressing parameters of other hot pressing areas 115 are adjusted according to the hot pressing parameters of the reference hot pressing area. The hot pressing parameters of other hot pressing areas 115 can be adjusted in a targeted manner according to the hot pressing parameters of the reference hot pressing area, thereby achieving accurate control of the porosity of each hot pressing area 115.

[0127] Optionally, adjusting the hot pressing parameters of other hot pressing areas 115 according to the hot pressing parameters of the reference hot pressing area specifically includes adjusting at least one hot pressing parameter of other hot pressing areas 115 according to the difference between the capacity reduction of the electrode assembly 11 of the other hot pressing area 115 and the capacity reduction of the electrode assembly 11 of the reference hot pressing area.

[0128] The adjustment of at least one hot pressing parameter of other hot pressing areas 115 mentioned here may be the hot pressing temperature or the hot pressing time. For example, if the capacity reduction of the electrode assembly 11 in the first hot pressing area 1151 is 1% greater than the capacity reduction of the electrode assembly 11 in the second hot pressing area 1152, the hot pressing temperature of the first hot pressing area 1151 may be increased by 3 to 5 degrees Celsius, or the hot pressing pressure of the first hot pressing area 1151 may be increased by 2 to 4 MPa. Of course, the hot pressing temperature of the first hot pressing area 1151 may be adjusted and the hot pressing pressure of the first hot pressing area 1151 may be increased at the same time, such as increasing the hot pressing temperature of the first hot pressing area 1151 by 1 degree Celsius and increasing the hot pressing pressure of the first hot pressing area 1151 by 2 MPa. Of course, when determining the hot pressing pressure or hot pressing temperature of each hot pressing area 115 here, it may be adjusted according to experience and test data, so as to achieve precise control of the porosity of the diaphragm in each hot pressing area 115.

[0129] The embodiments of the present application adjust at least one hot pressing parameter of other hot pressing regions 115 according to the difference between the capacity reduction of the electrode assembly 11 in other hot pressing regions 115 and the capacity reduction of the electrode assembly 11 in the reference hot pressing region. This can more accurately adjust the hot pressing parameters of other hot pressing regions 115, thereby enabling accurate control of the porosity of each hot pressing region 115.

[0130] In some embodiments of the present application, before hot pressing the multiple hot pressing areas 115 using different hot pressing parameters, the preparation method further includes preparing the electrode assembly 11 and fixing the electrode assembly 11 on the hot pressing device 500 .

[0131] Among them, the preparation of the electrode assembly 11 can be to stack or wind the positive electrode plate 111, the separator 113 and the negative electrode plate 112 into the electrode assembly 11, and the hot pressing device 500 can fix the electrode assembly 11 and can realize hot pressing of the electrode assembly 11.

[0132] The embodiment of the present application prepares the electrode assembly 11 and fixes the electrode assembly 11 on the hot pressing device 500, which can facilitate the hot pressing of multiple hot pressing areas 115 of the electrode assembly 11, thereby improving the efficiency of the preparation method of the electrode assembly 11.

[0133] Optionally, the preparation method of the electrode assembly 11 also includes preheating the electrode assembly 11, wherein the electrode assembly 11 can be placed in a heating furnace and heated for 300 to 600 seconds so that the temperature of the electrode assembly 11 is maintained at about 100 degrees Celsius, and then the preheated electrode assembly 11 is fixed on a hot pressing device 500 to achieve hot pressing of the electrode assembly 11.

[0134] It should be noted that the hot pressing parameters also include hot pressing time and other parameters, wherein the hot pressing time can be selected to be 30 seconds to 300 seconds, etc. For different hot pressing areas 115, the hot pressing time can be selected as a consistent parameter without the need for zoning settings.

[0135] The second aspect of the embodiment of the present application provides a hot pressing device 500, such as Figure 8 As shown, the hot pressing device 500 is used to implement the preparation method of the electrode assembly 11 mentioned in the above embodiment.

[0136] The embodiment of the present application uses a hot pressing device 500 and the preparation method of the electrode assembly 11 mentioned in the above embodiment, so that the porosity of the diaphragm 113 of multiple hot pressing areas 115 can be reduced from the middle position to both sides along the first direction, thereby reducing the reaction rate of the middle position of the electrode assembly 11 along the first direction, making the reaction rates of different positions of the electrode assembly 11 along the first direction approach to the same, thereby reducing the attenuation rate of the electrode assembly 11.

[0137] In some embodiments of the present application, Figure 8 As shown, the hot pressing device 500 includes a first pressing plate 501 and a second pressing plate 502, a driving member 504 and a heating member 505 which are arranged relatively at intervals. An installation space 503 for placing the electrode assembly 11 is formed between the first pressing plate 501 and the second pressing plate 502; the driving member 504 is transmission-connected to at least one of the first pressing plate 501 and the second pressing plate 502, so that the first pressing plate 501 and the second pressing plate 502 are closer to or farther away from each other; wherein the heating member 505 is thermally connected to the first pressing plate 501 and the second pressing plate 502, respectively.

[0138] The driving component 504 here can be a motor or a hydraulic driving component, which can drive the first pressing plate 501 or the second pressing plate 502.

[0139] The heating element 505 here may be an electric heating element or other heating element, which can heat the electrode assembly 11. Optionally, the heating element 505 includes a plurality of independent heating plates 5051, and each heating plate 5051 heats a hot pressing area separately.

[0140] The embodiment of the present application is to set a first pressing plate 501 and a second pressing plate 502 which are relatively spaced apart, and to set a driving member 504 and a heating member 505, wherein an installation space 503 for placing the electrode assembly 11 is formed between the first pressing plate 501 and the second pressing plate 502; the driving member 504 is transmission-connected to at least one of the first pressing plate 501 and the second pressing plate 502, so that the first pressing plate 501 and the second pressing plate 502 are closer to or farther away from each other; wherein the heating member 505 is thermally connected to the first pressing plate 501 and the second pressing plate 502, respectively, so that the electrode assembly 11 can be heated by the heating member 505, and the electrode assembly 11 can be pressurized by the first pressing plate 501 and the second pressing plate 502 at the same time, thereby realizing hot pressing of the electrode assembly 11.

[0141] In some embodiments of the present application, Figure 8 As shown, the first pressure plate 501 includes multiple independent first sub-pressure plates 5011, and each first sub-pressure plate 5011 is respectively arranged corresponding to a hot pressing area 115; and / or, the second pressure plate 502 includes multiple independent second sub-pressure plates 5021, and each second sub-pressure plate 5021 is respectively arranged corresponding to the first sub-pressure plate 5011.

[0142] The multiple first sub-pressing plates 5011 here are independent of each other, and the multiple second sub-pressing plates 5021 are also independent of each other. Each first sub-pressing plate 5011 can apply different hot pressing pressures to the electrode assembly 11, and each second sub-pressing plate 5021 can also apply different hot pressing pressures to the electrode assembly 11.

[0143] In the embodiment of the present application, the first pressing plate 501 includes a plurality of independent first sub-pressing plates 5011, and each first sub-pressing plate 5011 is respectively arranged corresponding to a hot pressing area 115; the second pressing plate 502 includes a plurality of independent second sub-pressing plates 5021, and each second sub-pressing plate 5021 is respectively arranged corresponding to the first sub-pressing plate 5011. Then, hot pressing of a hot pressing area 115 can be achieved by respectively using a first sub-pressing plate 5011 and the corresponding second sub-pressing plate 5021, thereby achieving separate hot pressing of multiple hot pressing areas 115 of the electrode assembly 11.

[0144] Optionally, the hot pressing device 500 also includes a temperature controller 506, a pressure controller 507 and a display and operating console 508, wherein the temperature controller 506 can control the temperature, the pressure controller 507 can control the pressure, and the display and operating console 508 can facilitate the user to operate and adjust the pressure and temperature.

[0145] The test results of the electrode assembly 11 of the present application are further described in detail below in combination with Examples 1-5 and Comparative Example 1. However, it should be understood that the embodiments of the present application are only for explaining the present application, not for limiting the present application, and the embodiments of the present application are not limited to the embodiments given in the specification. The specific experimental conditions or operating conditions not specified in the embodiments are made under conventional conditions, or under the conditions recommended by the material supplier.

[0146] Embodiment 1 can be operated according to the following steps: simulate the working condition of the battery cell 10, perform 200 charge and discharge cycles, test the temperature distribution of the battery cell 10, record the hot pressing pressure and hot pressing temperature, and the retention ratio of the residual capacity of the battery cell 10 relative to the initial capacity, that is, the 200cls capacity retention rate in Table 1, wherein the hot pressing pressure of the first hot pressing area 1151 is 10MPa, the hot pressing pressure of the second hot pressing area 1152 is 8MPa, the hot pressing pressure of the third hot pressing area 1153 is 6MPa, the hot pressing pressure of the fourth hot pressing area 1154 is 4MPa, and the hot pressing pressure of the fifth hot pressing area 1155 is 2MPa, and the hot pressing temperature of each hot pressing area 115 is 80°C, so that the porosity of the diaphragm 113 in the first hot pressing area 1151 is the smallest, and the porosity of the diaphragm 113 gradually increases from the second hot pressing area 1152 to the fifth hot pressing area 1155, and the 200cls capacity retention rate of the battery cell 10 is 87%.

[0147] Embodiment 2 has the same operating steps as the above-mentioned embodiment 1, except that the hot pressing pressure of each hot pressing area 115 is different from that in embodiment 1, the hot pressing pressure of the first hot pressing area 1151 is 20MPa, the hot pressing pressure of the second hot pressing area 1152 is 15MPa, the hot pressing pressure of the third hot pressing area 1153 is 12MPa, the hot pressing pressure of the fourth hot pressing area 1154 is 10MPa, and the hot pressing pressure of the fifth hot pressing area 1155 is 6MPa. The hot pressing temperature of each hot pressing area 115 is 80°C, so that the porosity of the diaphragm 113 in the first hot pressing area 1151 is the smallest, and the porosity of the diaphragm 113 gradually increases from the second hot pressing area 1152 to the fifth hot pressing area 1155, and the 200cls capacity retention rate of the battery cell 10 is 92%.

[0148] Example 3 has the same operating steps as the above-mentioned Example 1, except that the hot pressing pressure of each hot pressing area 115 is different from that in Example 1, the hot pressing pressure of the first hot pressing area 1151 is 5 MPa, the hot pressing pressure of the second hot pressing area 1152 is 5 MPa, the hot pressing pressure of the third hot pressing area 1153 is 5 MPa, the hot pressing pressure of the fourth hot pressing area 1154 is 5 MPa, and the hot pressing pressure of the fifth hot pressing area 1155 is 5 MPa. The hot pressing temperature of each hot pressing area 115 is 160°C, so that the porosity of each hot pressing area 115 is 42%, and the 200cls capacity retention rate of the battery cell 10 is 88%. Compared with Comparative Example 1, the 200cls capacity retention rate of the battery cell 10 is improved to a certain extent.

[0149] Example 4 has the same operating steps as the above-mentioned Example 1, except that the hot pressing pressure of each hot pressing area 115 is different from that in Example 1, the hot pressing pressure of the first hot pressing area 1151 is 10MPa, the hot pressing pressure of the second hot pressing area 1152 is 8MPa, the hot pressing pressure of the third hot pressing area 1153 is 6MPa, the hot pressing pressure of the fourth hot pressing area 1154 is 4MPa, and the hot pressing pressure of the fifth hot pressing area 1155 is 2MPa. The hot pressing temperature of each hot pressing area 115 is 160°C, so that the porosity of the diaphragm 113 in the first hot pressing area 1151 is the smallest, and the porosity of the diaphragm 113 gradually increases from the second hot pressing area 1152 to the fifth hot pressing area 1155, and the 200cls capacity retention rate of the battery cell 10 is 93%.

[0150] Example 5 has the same operating steps as the above-mentioned Example 1, except that the hot pressing pressure of each hot pressing area 115 is different from that in Example 1, the hot pressing pressure of the first hot pressing area 1151 is 20MPa, the hot pressing pressure of the second hot pressing area 1152 is 15MPa, the hot pressing pressure of the third hot pressing area 1153 is 12MPa, the hot pressing pressure of the fourth hot pressing area 1154 is 10MPa, and the hot pressing pressure of the fifth hot pressing area 1155 is 6MPa. The hot pressing temperature of each hot pressing area 115 is 160°C, so that the porosity of the diaphragm 113 in the first hot pressing area 1151 is the smallest, and the porosity of the diaphragm 113 gradually increases from the second hot pressing area 1152 to the fifth hot pressing area 1155, and the 200cls capacity retention rate of the battery cell 10 is 83%.

[0151] Comparative Example 1 has the same operating steps as the above-mentioned Example 1, except that the hot pressing pressure of each hot pressing area 115 is the same, which is 5 MPa, and the hot pressing temperature is 80° C. The 200 cls capacity retention rate of the battery cell 10 is 82%.

[0152] The evaluation structures of Examples 1 to 5 and Comparative Example 1 are shown in Table 1.

[0153] Table 1 compares the results of the embodiment of the electrode assembly 11 with those of the comparative example.

[0154]

[0155] Among them, 1, 2, 3, 4 and 5 in the table represent five hot pressing areas respectively, among which 1 represents the first hot pressing area 1151, 2 represents the second hot pressing area 1152, 3 represents the third hot pressing area 1153, 4 represents the fourth hot pressing area 1154, and 5 represents the fifth hot pressing area 1155.

[0156] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below.

[0157] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below.

[0158] The first aspect of the embodiment of the present application provides a method for preparing an electrode assembly 11, the method comprising providing an electrode assembly 11, the electrode assembly 11 comprising a diaphragm 113; dividing the electrode assembly 11 into a plurality of hot pressing regions 115 along a first direction; hot pressing the plurality of hot pressing regions 115 using different hot pressing parameters respectively, so that the porosity of the diaphragm 113 decreases from the middle position to both sides along the first direction; wherein the first direction is the height direction of the electrode assembly 11. Further, the plurality of hot pressing regions 115 comprise a first hot pressing region 1151 and a second hot pressing region 1152, wherein the first hot pressing region 1151 is arranged at the middle position, and the second hot pressing regions 1152 are arranged on opposite sides of the first hot pressing region 1151 along the first direction; wherein at least one hot pressing parameter of the first hot pressing region 1151 is greater than the corresponding hot pressing parameter of the second hot pressing region 1152, so that the porosity of the diaphragm 113 of the first hot pressing region 1151 is less than the porosity of the diaphragm 113 of the second hot pressing region 1152. Further, the plurality of hot pressing regions 115 include a third hot pressing region 1153, the third hot pressing region 1153 is provided on the side of the second hot pressing region 1152 away from the first hot pressing region 1151, and at least one hot pressing parameter of the second hot pressing region 1152 is greater than the corresponding hot pressing parameter of the third hot pressing region 1153. Further, before hot pressing the plurality of hot pressing regions 115 respectively with different hot pressing parameters, the preparation method further includes obtaining the operating parameter distribution of the electrode assembly 11; dividing the plurality of hot pressing regions 115 according to the operating parameter distribution, and determining the hot pressing parameters of each hot pressing region 115. Further, the operating parameter distribution includes the temperature distribution of the electrode assembly 11 and the capacity reduction of the electrode assembly 11; dividing the plurality of hot pressing regions 115 according to the operating parameter distribution, and determining the hot pressing parameters of each hot pressing region 115 specifically includes: dividing the plurality of hot pressing regions 115 according to the temperature distribution of the electrode assembly 11, and determining the hot pressing parameters of each hot pressing region 115 according to the capacity reduction of the electrode assembly 11 in each hot pressing region 115. Further, determining the hot pressing parameters of each hot pressing area 115 according to the capacity reduction of the electrode assembly 11 in each hot pressing area 115 specifically includes determining the hot pressing area 115 with the smallest capacity reduction of the electrode assembly 11 as the reference hot pressing area; adjusting the hot pressing parameters of other hot pressing areas 115 according to the hot pressing parameters of the reference hot pressing area. Further, adjusting the hot pressing parameters of other hot pressing areas 115 according to the hot pressing parameters of the reference hot pressing area specifically includes adjusting at least one hot pressing parameter of other hot pressing areas 115 according to the difference between the capacity reduction of the electrode assembly 11 in other hot pressing areas 115 and the capacity reduction of the electrode assembly 11 in the reference hot pressing area. Further, the hot pressing parameters include hot pressing temperature and hot pressing time. Further, before hot pressing multiple hot pressing areas 115 respectively using different hot pressing parameters, the preparation method also includes preparing the electrode assembly 11 and fixing the electrode assembly 11 on the hot pressing device 500.

[0159] The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for preparing an electrode assembly, characterized in that: The preparation method comprises: providing an electrode assembly, the electrode assembly comprising a separator; Dividing the electrode assembly into a plurality of hot pressing areas along a first direction; Performing hot pressing on the multiple hot pressing regions using different hot pressing parameters respectively, so that the porosity of the diaphragm decreases from the middle position to both sides along the first direction; Wherein, the first direction is the height direction of the electrode assembly.

2. The method for preparing an electrode assembly according to claim 1, wherein: The multiple hot pressing areas include a first hot pressing area and a second hot pressing area, wherein the first hot pressing area is arranged at the middle position, and the second hot pressing areas are respectively arranged on opposite sides of the first hot pressing area along the first direction; At least one hot pressing parameter of the first hot pressing region is greater than a corresponding hot pressing parameter of the second hot pressing region, so that the porosity of the diaphragm in the first hot pressing region is smaller than the porosity of the diaphragm in the second hot pressing region.

3. The method for preparing an electrode assembly according to claim 2, wherein: The multiple hot pressing areas include a third hot pressing area, the third hot pressing area is provided on the side of the second hot pressing area away from the first hot pressing area, and at least one hot pressing parameter of the second hot pressing area is greater than the corresponding hot pressing parameter of the third hot pressing area.

4. The method for preparing an electrode assembly according to claim 1, wherein: Before hot pressing the multiple hot pressing regions respectively using different hot pressing parameters, the preparation method further includes: Obtaining an operating parameter distribution of the electrode assembly; The plurality of hot pressing regions are divided according to the distribution of the operating parameters, and the hot pressing parameters of each of the hot pressing regions are determined.

5. The method for preparing an electrode assembly according to claim 4, characterized in that: The operating parameter distribution includes a temperature distribution of the electrode assembly and a capacity reduction of the electrode assembly; Dividing the plurality of hot pressing regions according to the distribution of the operating parameters and determining the hot pressing parameters of each of the hot pressing regions specifically includes: dividing the plurality of hot pressing regions according to the temperature distribution of the electrode assembly; A hot pressing parameter of each hot pressing zone is determined according to a capacity reduction amount of the electrode assembly in each hot pressing zone.

6. The method for preparing an electrode assembly according to claim 5, characterized in that: Determining the hot pressing parameters of each hot pressing area according to the capacity reduction of the electrode assembly in each hot pressing area specifically includes: Determine a hot pressing region where the capacity reduction of the electrode assembly is the smallest as a reference hot pressing region; According to the hot pressing parameters of the reference hot pressing area, the hot pressing parameters of the other hot pressing areas are adjusted.

7. The method for preparing an electrode assembly according to claim 6, wherein: According to the hot pressing parameters of the reference hot pressing area, adjusting the hot pressing parameters of other hot pressing areas specifically includes: At least one of the hot pressing parameters of the other hot pressing regions is adjusted according to the difference between the capacity reduction of the electrode assembly in the other hot pressing regions and the capacity reduction of the electrode assembly in the reference hot pressing region.

8. The method for preparing an electrode assembly according to any one of claims 1 to 7, characterized in that: The hot pressing parameters include hot pressing temperature and hot pressing time.

9. The method for preparing an electrode assembly according to any one of claims 1 to 7, characterized in that: Before hot pressing the multiple hot pressing regions respectively using different hot pressing parameters, the preparation method further includes: The electrode assembly is prepared and fixed on a hot pressing device.

10. A hot pressing device, characterized in that: The hot pressing device is used to implement the method for preparing an electrode assembly according to any one of claims 1 to 9.

11. The hot pressing device according to claim 10, characterized in that: The hot pressing device comprises: A first pressing plate and a second pressing plate are arranged relatively spaced apart, and an installation space for placing the electrode assembly is formed between the first pressing plate and the second pressing plate; a driving member, the driving member being drivingly connected to at least one of the first pressing plate and the second pressing plate so that the first pressing plate and the second pressing plate move closer to or farther from each other; and A heating element, wherein the heating element is thermally connected to the first pressing plate and the second pressing plate respectively.

12. The hot pressing device according to claim 11, characterized in that: The first pressing plate includes a plurality of independent first sub-pressing plates, each of which is respectively arranged corresponding to one of the hot pressing areas; and / or the second pressing plate includes a plurality of independent second sub-pressing plates, each of which is respectively arranged corresponding to one of the first sub-pressing plates. 13 . A battery cell, comprising an electrode assembly manufactured by the method for manufacturing an electrode assembly according to claim 1 .

14. A battery device, characterized in that: include: Battery box: and The battery cell according to claim 13, wherein the battery cell is disposed in the battery box.

15. An electrical equipment, characterized in that: The battery device as claimed in claim 14 is used to store or provide electrical energy.

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