Method for manufacturing pole piece, battery cell, battery device, and electric device

Abstract

This application relates to the field of battery manufacturing technology, and more particularly to a method for preparing an electrode sheet, a battery cell, a battery device, and an electrical device. The preparation method includes obtaining at least one test temperature value of the coating area of ​​a battery cell under test conditions; dividing the coating area into multiple coating regions based on the test temperature value; obtaining the capacity distribution of the coating area of ​​the battery cell under test conditions; determining the capacity change of the coating area based on the capacity distribution; determining the coating region with the least capacity change as a reference coating region based on the capacity change of each coating region; adjusting the coating parameters of other coating regions based on the coating parameters of the reference coating region; and preparing an electrode sheet according to the adjusted coating parameters of the coating regions. The electrode sheet has different initial capacities in different coating regions, and the residual capacity in different regions is relatively balanced, reducing the capacity decay of the battery cell.

Description

Technical Field

[0001] This application relates to the field of battery manufacturing technology, and in particular to a method for preparing an electrode sheet, a battery cell, a battery device, and an electrical device. Background Technology

[0002] This section provides only background information relevant to this disclosure and is not necessarily prior art.

[0003] With the increasing maturity of new energy technologies, 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 ineffective heat dissipation. This causes the middle part of the electrode assembly to become the area with the fastest reaction rate and the highest capacity decay. This results in inconsistent capacity decay in different positions of the electrode coating area, which can easily lead to excessively rapid capacity decay of the electrode assembly. Summary of the Invention

[0005] In view of the above problems, this application provides a method for preparing an electrode sheet, a battery cell, a battery device, and an electrical device, which solves the problem of excessively rapid capacity decay of electrode components caused by inconsistent capacity decay in different locations of the coating area of ​​the electrode sheet in the prior art.

[0006] The first aspect of the embodiments of this application discloses a method for preparing an electrode sheet, wherein the electrode sheet has a coating area and is applied to a battery cell. The preparation method includes:

[0007] Obtain at least one test temperature value of the coating area of ​​the battery cell when it is under test, and divide the coating area into multiple coating regions according to the test temperature value.

[0008] Obtain the capacity distribution of the coated area of ​​the battery cell under test conditions, and determine the capacity change of the coated area based on the capacity distribution of the coated area;

[0009] Based on the amount of capacity change in each coating area, the coating area with the least capacity change is determined as the reference coating area, and the coating parameters of other coating areas are adjusted according to the coating parameters of the reference coating area.

[0010] Electrodes were prepared according to the adjusted coating parameters of the coating area.

[0011] The electrode preparation method of the embodiments of this application can determine the coating area with the least capacity change as the reference coating area based on the temperature test value and capacity change of the coating area of ​​the electrode, and adjust the coating parameters of other coating areas according to the coating parameters of the reference coating area, and prepare the electrode according to the adjusted coating parameters of the coating areas. This can make the electrode have different initial capacities in different coating areas. Since the reaction rates of different coating areas are different, the area with the fastest reaction rate has the largest initial capacity, and the area with the slowest reaction rate has the smallest initial capacity. This can make the residual capacity of the electrode after full discharge more balanced in different coating areas, and reduce the capacity decay of the battery cell.

[0012] In some embodiments of this application, the coating parameters include at least one of the following: coating slurry formulation, compaction density, and coating weight.

[0013] The embodiments of this application, by including at least one of the coating parameters such as the coating slurry formulation, compaction density, and coating weight, can prepare an adjusted electrode sheet by adjusting at least one of the coating slurry formulation, compaction density, and coating weight, so that the residual capacity of the electrode sheet after full loading is more balanced in different regions, thereby reducing the capacity decay of the battery cell.

[0014] In some embodiments of this application, determining the capacity change of the coating area based on the capacity distribution of the coating area specifically includes obtaining the difference between the initial capacity of the coating area and the residual capacity of the coating area, and then determining the capacity change of the coating area.

[0015] The embodiments of this application determine the amount of capacity change in the coating area by obtaining the difference between the initial capacity and the residual capacity of the coating area. Based on the amount of capacity change in the coating area in different regions, the coating parameters are adjusted.

[0016] In some embodiments of this application, dividing the coating area into multiple coating regions according to the test temperature value includes extending from the middle region of the coating area to both sides along the width direction of the electrode sheet, and dividing the coating regions according to the temperature range, wherein the middle region is the region with the highest average temperature.

[0017] The embodiments of this application extend the coating area from the middle region to both sides along the width direction of the electrode, and divide the coating area according to the temperature range. The middle region is the region with the highest average temperature. This allows the coating area to be divided into multiple coating areas along the width direction of the electrode according to the temperature distribution. Different coating parameters are used to control each coating area, thereby improving the uniformity of the residual capacity of the electrode in different regions.

[0018] In some embodiments of this application, the coating area is divided into two parts according to the temperature range, extending from the middle region of the coating area along the width direction of the electrode. This includes determining the region with the highest average temperature as the first coating area; extending from the region with the highest average temperature along the width direction of the electrode to both sides, the region with the temperature in the first range is the second coating area, and the average temperature of the first range is lower than the average temperature of the region with the highest average temperature.

[0019] The embodiments of this application divide the coating area into two regions based on the temperature range by extending from the middle region of the coating area along the width direction of the electrode sheet. This includes determining the region with the highest average temperature as the first coating area; extending from the region with the highest average temperature along the width direction of the electrode sheet to both sides, the region with the temperature within the first range is designated as the second coating area, and the average temperature of the first range is lower than the average temperature of the region with the highest average temperature. Therefore, the coating area can be divided into the first coating area and the second coating area along the width direction of the electrode sheet according to the different average temperatures. This allows the first coating area and the second coating area to be coated with different coating parameters, thereby achieving zoned coating of the coating area.

[0020] In some embodiments of this application, the coating area extends from the middle region to both sides along the width direction of the electrode. Dividing the coating area according to the temperature range also includes extending along the width direction of the electrode from the second coating area to the direction away from the region with the highest average temperature. The region with the temperature in the second range is the third coating area, and the average temperature of the second range is lower than the average temperature of the first range.

[0021] The embodiments of this application define a third coating region by extending along the width of the electrode from the second coating region toward the region with the highest average temperature. The region with the temperature in the second interval range is the third coating region, and the average temperature in the second interval range is lower than the average temperature in the first interval range. Therefore, the first coating region, the second coating region, and the third coating region can be coated with different coating parameters respectively, thereby achieving zoned coating of the coating area.

[0022] In some embodiments of this application, the coating region with the smallest capacity change is determined as the reference coating region based on the capacity change of each coating region. The coating parameters of other coating regions are adjusted according to the coating parameters of the reference coating region. This includes increasing the initial capacity of the first coating region based on the difference between the capacity change of the first coating region and the capacity change of the third coating region, and increasing the initial capacity of the second coating region based on the difference between the capacity change of the second coating region and the capacity change of the third coating region, so that the residual capacities of the first, second, and third coating regions are consistent. The third coating region is the coating region with the smallest capacity change and is the reference coating region.

[0023] The embodiments of this application increase the initial capacity of the first coating region based on the difference between the capacity change in the first coating region and the capacity change in the third coating region, and increase the initial capacity of the second coating region based on the difference between the capacity change in the second coating region and the capacity change in the third coating region, so that the residual capacity of the first coating region, the second coating region and the third coating region are consistent. This makes the residual capacity of the electrode coating area basically consistent in different regions, reducing the capacity decay of the battery cell.

[0024] In some embodiments of this application, the initial capacity of the first coating region is increased by increasing the proportion of at least one high specific capacity material in the coating slurry of the first coating region, increasing the coating weight of the first coating region, and increasing the compaction density of the first coating region, wherein the specific capacity of the high specific capacity material is greater than 500 mAh / g.

[0025] In the embodiments of this application, the initial capacity of the first coating region is increased by increasing the proportion of at least one high specific capacity material in the coating slurry of the first coating region, increasing the coating weight of the first coating region, and increasing the compaction density of the first coating region. This allows for convenient adjustment of the initial capacity of the first coating region and increases the initial capacity of the first coating region.

[0026] In some embodiments of this application, the initial capacity of the second coating region is increased by increasing the proportion of at least one high specific capacity material in the coating slurry of the second coating region, increasing the coating weight of the second coating region, and increasing the compaction density of the second coating region, wherein the specific capacity of the high specific capacity material is greater than 500 mAh / g.

[0027] In the embodiments of this application, the initial capacity of the second coating region is increased by increasing the proportion of at least one high specific capacity material in the coating slurry of the second coating region, increasing the coating weight of the second coating region, and increasing the compaction density of the second coating region. This allows for convenient adjustment of the initial capacity of the second coating region and increases the initial capacity of the second coating region.

[0028] In some embodiments of this application, based on the amount of capacity change in each coating region, the coating region with the smallest capacity change is determined as the reference coating region, and the coating parameters of other coating regions are adjusted according to the coating parameters of the reference coating region, including:

[0029] The electrode is determined to be a cathode electrode. Based on the difference between the capacity change in the first coating region and the capacity change in the third coating region, the initial capacity of the first coating region is reduced. Based on the difference between the capacity change in the second coating region and the capacity change in the third coating region, the initial capacity of the second coating region is reduced, so that the residual capacities of the first, second, and third coating regions are consistent. Among them, the third coating region is the coating region with the least capacity change.

[0030] The embodiments of this application reduce the initial capacity of the first coating region based on the difference between the capacity change in the first coating region and the capacity change in the third coating region, and reduce the initial capacity of the second coating region based on the difference between the capacity change in the second coating region and the capacity change in the third coating region, so that the residual capacity of the first coating region, the second coating region and the third coating region are consistent. This makes the residual capacity of the electrode coating area basically consistent in different regions, thereby reducing the capacity decay of the battery cell.

[0031] In some embodiments of this application, the initial capacity of the first coating region is reduced by increasing the proportion of at least one low specific capacity material in the coating slurry of the first coating region, reducing the coating weight of the first coating region, and reducing the compaction density of the first coating region, wherein the specific capacity of the low specific capacity material is less than or equal to 500 mAh / g.

[0032] In the embodiments of this application, reducing the initial capacity of the first coating region can be achieved by increasing the proportion of at least one low specific capacity material in the coating slurry of the first coating region, reducing the coating weight of the first coating region, and reducing the compaction density of the first coating region. This allows for convenient adjustment of the initial capacity of the first coating region and reduction of its initial capacity.

[0033] In some embodiments of this application, reducing the initial capacity of the second coating region is achieved by increasing the proportion of at least one low specific capacity material in the coating slurry of the second coating region, reducing the coating weight of the second coating region, and reducing the compaction density of the second coating region.

[0034] In the embodiments of this application, reducing the initial capacity of the second coating region can be achieved by increasing the proportion of at least one low specific capacity material in the coating slurry of the second coating region, reducing the coating weight of the second coating region, and reducing the compaction density of the second coating region. This allows for convenient adjustment of the initial capacity of the second coating region and reduction of its initial capacity.

[0035] In some embodiments of this application, the temperature distribution of the coated area is obtained by setting a temperature sensor on the surface of the coated area.

[0036] The embodiments of this application obtain the temperature distribution of the coating area by setting a temperature sensor on the surface of the coating area, which can realize accurate temperature measurement of the coating area and facilitate zoning according to the temperature range.

[0037] In some embodiments of this application, the capacity change of the coating area is determined based on the capacity distribution of the coating area by disassembling the electrode sheets into coin cells and performing discharge tests.

[0038] The embodiments of this application determine the residual capacity of the coated area by fabricating the disassembled electrode sheets into button cells. Based on the initial capacity and residual capacity of the electrode sheets, the capacity change in different areas of the coated area can be determined, making the test convenient and accurate.

[0039] In some embodiments of this application, preparing an electrode according to the coating parameters of the adjusted coating area includes coating the electrode with a coating device, wherein the coating device has multiple coating ports, and the multiple coating ports are arranged side by side along the width direction of the electrode.

[0040] The embodiments of this application employ a coating device to coat the electrode sheet. The coating device has multiple coating ports, which are arranged side by side along the width direction of the electrode sheet. This allows the electrode sheet to be coated sequentially through the multiple coating ports, thereby improving the coating efficiency of the electrode sheet.

[0041] A second aspect of the embodiments of this application provides a battery cell comprising an electrode prepared by the electrode preparation method mentioned in the embodiments above.

[0042] A third aspect of the embodiments of this application provides a battery device including a battery housing and battery cells as mentioned in the above embodiments, wherein the battery cells are disposed within the battery housing.

[0043] A fourth aspect of the embodiments of this application provides an electrical device that includes the battery device mentioned in the above embodiments, the battery device being used to store or provide electrical energy.

[0044] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0045] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0046] Figure 1 This application provides a schematic diagram of the structure of an electrical device according to some embodiments;

[0047] Figure 2 This is a schematic diagram of the structure of a battery device provided in some embodiments of this application;

[0048] Figure 3 This is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0049] Figure 4 This is a schematic diagram of the structure of an electrode assembly provided in some embodiments of this application;

[0050] Figure 5 This is a schematic diagram of the structure of the electrode provided in some embodiments of this application;

[0051] Figure 6 This is a schematic diagram of the coating apparatus provided in some embodiments of this application;

[0052] Figure 7 for Figure 6 A schematic cross-sectional view of the coating apparatus shown along section AA.

[0053] Figure 8 for Figure 5 The diagram shows the structure of the electrode plate from a second-angle perspective (the electrode tab is not shown).

[0054] Figure 9 A flowchart illustrating a method for preparing an electrode according to some embodiments of this application.

[0055] The attached figures are labeled as follows:

[0056] 100. Battery device; 200. Vehicle; 300. Controller; 400. Motor;

[0057] 10. Battery cell; 11. Electrode assembly; 111. Positive electrode; 1111. Positive electrode coating area; 112. Negative electrode; 1121. Negative electrode coating area; 113. Separator; 114. First coating area; 115. Second coating area; 116. Third coating area; 117. Tab; 12. Housing; 121. Housing body; 122. End cap;

[0058] 20. Battery housing; 21. First housing; 22. Second housing; 23. Storage space;

[0059] 500. Coating apparatus; 501. First coating system; 5011. First coating channel; 5012. First coating port; 5013. First slurry coating area; 502. Second coating system; 5021. Second coating channel; 5022. Second coating port; 5023. Second slurry coating area; 503. Third coating system; 5031. Third coating channel; 5032. Third coating port; 5033. Third slurry coating area; 504. Fourth coating system; 5041. Fourth coating channel; 5042. Fourth coating port; 5043. Fourth slurry coating area;

[0060] 600, Substrate;

[0061] XX, the width direction of the electrode;

[0062] YY, the length direction of the electrode. Detailed Implementation

[0063] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0064] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0065] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0066] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0067] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0068] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0069] In the description of the embodiments of this application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0070] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0071] Currently, judging from market trends, the application of battery devices is becoming increasingly widespread. Battery devices are not only used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, but also widely applied in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. With the continuous expansion of battery device applications, market demand is also constantly increasing.

[0072] The battery devices described in this application can be used, but are not limited to, in electrical equipment such as vehicles, ships, or aircraft. Such electrical equipment can be composed of battery cells and battery devices as described in this application.

[0073] In this application embodiment, the electrical devices using battery devices as power sources can be, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0074] It should be understood that the technical solutions described in the embodiments of this application are not limited to the battery devices and electrical equipment described above, but can also be applied to all batteries including housings and electrical equipment using batteries.

[0075] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly consists of a positive electrode, a negative electrode, and a separator. The battery cell primarily functions by the movement of metal ions between the positive and negative electrodes. The positive electrode 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. Current collectors without the positive active material layer protrude beyond those with the coating. These uncoated current collectors are stacked together to form the positive electrode tab. Taking a lithium-ion battery as an example, the positive current collector can be made of aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode 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. Current collectors without the negative active material layer protrude beyond those with the coating. These uncoated current collectors are stacked together to form the negative electrode tab. The negative current collector can be made of copper, and the negative active material can be carbon or silicon, etc. The separator can be made of PP (polypropylene) or PE (polyethylene), etc. Furthermore, the electrode assembly can be a wound structure or a stacked structure; the embodiments of this application are not limited to these.

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

[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 ineffective heat dissipation. This causes the middle part of the electrode assembly to become the area with the fastest reaction rate and the highest capacity decay. This results in inconsistent capacity decay in different positions of the electrode coating area, which can easily lead to excessively rapid capacity decay of the electrode assembly.

[0078] To address this problem, embodiments of this application propose a method for preparing an electrode sheet. The electrode sheet has a coating area and is applied to a battery cell. The preparation method includes obtaining at least one test temperature value of the coating area of ​​the battery cell under test conditions; dividing the coating area into multiple coating regions based on the test temperature value; obtaining the capacity distribution of the coating area of ​​the battery cell under test conditions and determining the capacity change of the coating area based on the capacity distribution; determining the coating region with the smallest capacity change as a reference coating region based on the capacity change of each coating region; adjusting the coating parameters of other coating regions based on the coating parameters of the reference coating region; and preparing the electrode sheet according to the adjusted coating parameters of the coating regions. The electrode preparation method of the embodiments of this application can determine the coating area with the least capacity change as the reference coating area based on the test temperature value and capacity change of the coating area of ​​the electrode, and based on the capacity change of each coating area. The coating parameters of other coating areas are adjusted according to the coating parameters of the reference coating area, and the electrode is prepared according to the adjusted coating parameters of the coating areas. This can make the electrode have different initial capacities in different coating areas, so that the residual capacity of the electrode after full discharge is relatively balanced in different areas, thereby reducing the capacity decay of the battery cell.

[0079] The electrode preparation method in the embodiments of this application can be used in the production process of battery cells to prepare electrode sheets with partitioned coating areas.

[0080] The structures in the embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0081] For ease of explanation, the following embodiments use a vehicle as an example of electrical equipment.

[0082] Combined with appendix Figure 1 As shown, vehicle 200 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 100 is installed inside vehicle 200, and the battery device 100 can be located at the bottom, front, or rear of vehicle 200. The battery device 100 can be used to power vehicle 200; for example, the battery device 100 can serve as the operating power source for vehicle 200. Vehicle 200 may also include a controller 300 and a motor 400. The controller 300 is used to control the battery device 100 to supply power to the motor 400, for example, to meet the power needs of vehicle 200 during starting, navigation, and driving.

[0083] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle 200, but also as the 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 appendix Figure 2 As shown in the figure, this application provides a battery device 100, which can be a secondary battery or a primary battery, and can also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited to these. Both the battery cell 10 and the battery device 100 can be cylindrical, flat, cuboid or other shapes.

[0085] The battery device 100 mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells 10, which are connected in series, parallel, or mixed connections via busbars.

[0086] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells 10; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells 10 together to form a single module. As an example, a battery module can be formed by bundling multiple battery cells 10 together with cable ties.

[0087] In some embodiments, the battery device 100 may be a battery pack, which includes a battery housing 20 and one or more individual battery cells housed within the battery housing 20.

[0088] As an example, the battery cell assembly can be a battery module, which can be housed in the battery housing 20 by fixing the battery module in the battery housing 20.

[0089] As an example, the battery cell assembly can also be housed in the battery housing 20 by directly fixing multiple battery cells 10 to the battery housing 20.

[0090] The battery housing 20 provides a receiving space 23 for the battery cell 10, and the battery housing 20 can adopt various structures. In some embodiments, the battery housing 20 may include a first housing 21 and a second housing 22, which cover each other, and the first housing 21 and the second housing 22 together define a receiving space 23 for accommodating the battery cell 10.

[0091] As an example, the battery housing 20 may be part of the chassis structure of the vehicle 200. For instance, the battery housing 20 may be at least part of the floor of the vehicle 200, or the frame of the battery housing 20 may be at least part of the crossbeams and longitudinal beams of the vehicle 200.

[0092] Combined with appendix Figure 4 and Figure 5 As shown, an embodiment of this application also provides a battery cell 10, which includes an electrode assembly 11 and a separator 113. The electrode assembly 11 includes a negative electrode 112 and a positive electrode 111. The positive electrode 111 includes a positive electrode coating area 1111, and the negative electrode 112 includes a negative electrode coating area 1121. Both the positive electrode 111 and the negative electrode 112 are provided with tabs 117.

[0093] In some embodiments, the battery cell 10 further includes a housing 12 and an adapter (not shown in the figure). The housing 12 includes a housing body 121 and an end cap 122. The housing body 121 has an open structure at the top. The electrode assembly 11 is installed inside the housing 12. The end cap 122 covers the housing body 121 and is connected to the tab 117 of the electrode assembly 11 through the adapter.

[0094] like Figure 9 As shown in the embodiments of this application, a method for preparing an electrode sheet is also proposed. The electrode sheet has a coating area and is applied to a battery cell 10. Here, the electrode sheet can be a positive electrode sheet 111 or a negative electrode sheet 112. The preparation method includes:

[0095] S91. Obtain at least one test temperature value of the coating area of ​​the battery cell 10 in the test state, and divide the coating area into multiple coating regions according to the test temperature value.

[0096] S92. Obtain the capacity distribution of the coated area of ​​the battery cell 10 in the test state, and determine the capacity change of the coated area based on the capacity distribution of the coated area.

[0097] S93. Based on the capacity change of each coating area, determine the coating area with the smallest capacity change as the reference coating area, and adjust the coating parameters of other coating areas according to the coating parameters of the reference coating area.

[0098] S94. Prepare electrode sheets according to the adjusted coating parameters of the coating area.

[0099] When the battery cell 10 is under test, it is usually charged at a low rate and discharged at a high power, which can easily lead to the electrode assembly 11 of the battery cell 10 decaying too quickly. Therefore, the embodiments of this application need to reduce the capacity decay of the battery cell 10.

[0100] In S91, obtaining at least one test temperature value of the coated area of ​​the battery cell 10 during the test state can be achieved by setting multiple temperature sensors in the coated area. In order not to affect the normal operation of the battery cell 10, the temperature sensors can also be set at different positions on the surface of the electrode assembly 11, and there can be multiple temperature sensors to detect the temperature at different positions of the electrode assembly 11. The test state mentioned here can be a fully discharged state, that is, the process of the battery cell 10 being fully charged and then fully discharged.

[0101] In S92, the capacity change can be a relative or absolute value. The absolute value can be obtained by measuring the difference between the capacity of the electrode in its fresh state and the residual capacity of the electrode. Alternatively, the capacity change can be determined by the ratio of the difference between the capacity of the electrode in its fresh state and the residual capacity of the electrode to the capacity of the electrode in its fresh state. Here, the capacity change is typically the decrease in capacity.

[0102] In S93, based on the amount of capacity change in each coating region, the coating region with the smallest capacity change is determined as the reference coating region. The coating parameters of other coating regions are adjusted based on the coating parameters of the reference coating region. In other words, there are multiple coating regions, and the amount of capacity change in the multiple coating regions is different. Therefore, the determination of the amount of capacity change in each coating region is a comparison with the coating region with the smallest capacity change. The coating parameters of the reference coating region can be used as the reference parameters for adjustment.

[0103] In S94, the electrode is prepared according to the coating parameters of the adjusted coating area. Specifically, this is achieved by increasing the initial capacity of the area with a large capacity change, which will be described in more detail later.

[0104] The electrode preparation method of the embodiments of this application can determine the coating area with the least capacity change as the reference coating area based on the temperature distribution and capacity change of the coating area of ​​the electrode, and based on the capacity change of each coating area. The coating parameters of other coating areas are adjusted according to the coating parameters of the reference coating area, and the electrode is prepared according to the adjusted coating parameters of the coating areas. This allows the electrode to have different initial capacities in different coating areas. Since the reaction rates of different coating areas are different, the initial capacity of the area with the fastest reaction rate is the largest, and the initial capacity of the area with the slowest reaction rate is the smallest. This can make the residual capacity of the fully discharged electrode relatively balanced in different coating areas, reducing the capacity decay of the battery cell 10.

[0105] Optionally, the coating parameters include at least one of the following: coating slurry formulation, compaction density, and coating weight.

[0106] It should be noted that the formulations of the coating slurry differ for cathode and anode electrodes. For example, for anode electrodes, raw materials such as high-capacity anode materials, graphite, binders, plasticizers, and conductive agents can be used. When an increase in initial capacity is required, the proportion of high-capacity materials can be increased. These high-capacity materials can be materials such as titanium dioxide, tin dioxide, and iron oxide, while reducing the graphite content. For cathode electrodes, ternary materials such as nickel-cobalt-manganese, high-capacity cathode materials, binders, conductive agents, and plasticizers can be used.

[0107] Compacted density refers to the density of the active material layer after it has been coated and compacted by equipment such as pressure rollers. The unit can be g / cm³. 3 In some embodiments, the compaction density of the active material layer can be in the range of 2.5 g / cm³. 3 Up to 5g / cm 3 Of course, the compaction density of battery cells 10 made of different materials may vary, and this embodiment will not list them one by one.

[0108] Coating weight refers to the coating weight at each detection location on the electrode. The coating weight can be obtained using any suitable method, such as a pre-set acquisition device like a thickness gauge, weight detector, or areal density meter. The coating weight data can refer to either weight or thickness.

[0109] The embodiments of this application, by including at least one of the coating parameters, such as the coating slurry formulation, compaction density, and coating weight, can prepare an adjusted electrode sheet by adjusting at least one of the coating slurry formulation, compaction density, and coating weight, so that the residual capacity of the fully loaded electrode sheet is more balanced in different regions, thereby reducing the capacity decay of the battery cell 10.

[0110] Optionally, determining the capacity change of the coating area based on the capacity distribution of the coating area specifically includes obtaining the difference between the initial capacity of the coating area and the residual capacity of the coating area, and determining the capacity change of the coating area.

[0111] The initial capacity of the coated area can be replaced by the theoretical capacity. For the positive electrode 111, the weight of the active material can be obtained by subtracting the weight of the substrate 600 from the weight of the positive electrode 111, and then multiplying by 140 mAh / g (lithium cobalt oxide) to obtain the theoretical capacity. For the negative electrode 112, it can be estimated as 1.05 to 1.1 times that of the positive electrode 111, or a similar method can be used, where the weight of the active material is multiplied by 300 mAh / g for calculation.

[0112] The embodiments of this application determine the amount of capacity change in the coating area by obtaining the difference between the initial capacity and the residual capacity of the coating area. Based on the amount of capacity change in the coating area in different regions, the coating parameters are adjusted.

[0113] More specifically, the residual capacity of the coated area can be obtained through discharge testing. Specifically, this can be achieved by disassembling the battery cell 10 to obtain the disassembled electrode sheets, and then fabricating these electrode sheets into coin cells. In other words, the capacity change in the coated area can be determined based on its capacity distribution by fabricating the disassembled electrode sheets into coin cells, detecting the residual capacity, and comparing it with the initial capacity to determine the amount of capacity change. The coin cells mentioned here are button-shaped batteries that can be used to evaluate the remaining capacity of the electrode sheets.

[0114] The embodiments of this application determine the residual capacity of the coated area by fabricating the disassembled electrode sheets into a button cell. Based on the difference between the initial capacity and the residual capacity, the capacity change in different areas of the coated area can be determined, making the test convenient and accurate.

[0115] The specific process of the discharge test includes the following steps:

[0116] The battery cell 10 is disassembled to obtain the disassembled electrode sheets;

[0117] 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.

[0118] Cut 5 to 10 round pieces from the electrode sheet, and select 5 round pieces with acceptable weight;

[0119] Place the qualified disc into the positive electrode side of the coin cell casing with the gasket placed in advance, with the coated side facing away from the positive electrode. Then, drop 1-2 drops of electrolyte onto the positive electrode 111, then place the separator 113 and drop 1-2 drops of electrolyte on it, then place the lithium sheet, gasket, and spring, and finally place the negative electrode side casing of the coin cell. After assembling, seal the casing with a sealing machine.

[0120] The active material content is calculated based on the weight of the weighed small discs, and the required charge / discharge current for coining is calculated based on the estimated active material capacity, and then a charge / discharge test is conducted.

[0121] Optionally, such as Figure 5 As shown, based on the temperature distribution of the coating area, the coating area is divided into multiple coating regions, including extending from the middle region of the coating area to both sides along the width direction of the electrode sheet, and the coating regions are divided according to the temperature range, wherein the middle region is the region with the highest average temperature.

[0122] exist Figure 5In the diagram, the XX direction represents the width of the electrode, and the YY direction represents its length. When the electrode is in a wound state, the XX direction is the height direction of the electrode assembly 11. The "middle region" refers to the middle position of the coating area along the XX direction. Considering that the length directions of the positive electrode 111 and the negative electrode 112 are consistent, the length direction of either the positive electrode 111 or the negative electrode 112 can be used to represent the length direction of the electrode. Similarly, the width directions of the positive electrode 111 and the negative electrode 112 are also consistent, and the width direction of either the positive electrode 111 or the negative electrode 112 can be used to represent the width direction of the electrode.

[0123] The embodiments of this application extend the coating area from the middle region to both sides along the width direction of the electrode, and divide the coating area according to the temperature range. The middle region is the region with the highest average temperature. This allows the coating area to be divided into multiple coating areas along the width direction of the electrode according to the temperature distribution. Different coating parameters are used to control each coating area, thereby improving the balance and consistency of the residual capacity of the electrode in different regions.

[0124] Optionally, continue to refer to Figure 5 and Figure 7 As shown, the coating area extends from the middle region to both sides along the width direction of the electrode sheet. The coating area is divided according to the temperature range, including determining the region with the highest average temperature as the first coating area 114; extending from the region with the highest average temperature to both sides along the width direction of the electrode sheet, the region with the temperature in the first range is the second coating area 115, and the average temperature of the first range is lower than the average temperature of the region with the highest average temperature.

[0125] It should be noted that there are two second coating regions 115, which are symmetrically arranged on both sides of the first coating region 114 along the XX direction. The temperature of the first coating region 114 is a range, and the temperature of the second coating region 115 is another range. For example, the temperature of the first coating region 114 is greater than or equal to 50 and less than 60 degrees Celsius, and the temperature of the second coating region 115 is greater than or equal to 41 and less than 48 degrees Celsius. The average temperature of the second coating region 115 is 44.5 degrees Celsius, and the average temperature of the region with the highest average temperature is 51.5 degrees Celsius.

[0126] The embodiments of this application divide the coating area into two regions based on the temperature range by extending from the middle region of the coating area to both sides along the width direction of the electrode. This includes determining the region with the highest average temperature as the first coating area 114; extending from the region with the highest average temperature to both sides along the width direction of the electrode, the region with the temperature within the first range is designated as the second coating area 115. Since the average temperature of the first range is lower than the average temperature of the region with the highest average temperature, the coating area can be divided into the first coating area 114 and the second coating area 115 along the width direction of the electrode according to the different average temperatures. This allows the first coating area 114 and the second coating area 115 to be coated with different coating parameters, thereby achieving zoned coating of the coating area.

[0127] Optionally, such as Figure 5 As shown, the coating area extends from the middle region to both sides along the width direction of the electrode. The coating area is divided according to the temperature range. It also extends along the width direction of the electrode from the second coating area 115 to the direction away from the region with the highest average temperature. The region with the temperature in the second range is the third coating area 116. The average temperature of the second range is lower than the average temperature of the first range. That is to say, the average temperature of the third coating area 116 is lower than the average temperature of the second coating area 115.

[0128] It is understood that there are two third coating regions 116, which are symmetrically arranged on both sides of the first coating region 114 along the XX direction. A second coating region 115 is arranged between the first coating region 114 and the third coating region 116. The second interval range corresponding to the third coating region 116 is greater than or equal to 34 degrees Celsius and less than 41 degrees Celsius. The average temperature of the second interval range is 36.5 degrees Celsius.

[0129] In this embodiment, by setting the area extending from the second coating region 115 away from the region with the highest average temperature along the width direction of the electrode, and the region with the temperature in the second interval range is the third coating region 116, and the average temperature of the second interval range is lower than the average temperature of the first interval range, the first coating region 114, the second coating region 115 and the third coating region 116 can be coated according to different coating parameters, thereby realizing the partitioned coating of the coating area.

[0130] Optionally, the coating area extends from the middle region of the coating area to both sides along the width direction of the electrode. The division of the coating area according to the temperature range also includes extending from the third coating area 116 in the direction away from the region with the highest average temperature along the width direction of the electrode. The region with the temperature in the third range is the fourth coating area, and the average temperature of the third range is lower than the average temperature of the second range.

[0131] There are two fourth coating regions, symmetrically located on both sides of the first coating region 114 along the XX direction, with a second coating region 115 and a third coating region 116 located between the first coating region 114 and the fourth coating region. In this case, the fourth coating region can be set as the reference coating region.

[0132] Understandably, depending on the temperature, the coating area can also be set to a fifth coating region, a sixth coating region, etc., and the temperature range used in each coating region can also be set as needed. For example, the temperature range corresponding to the first coating region 114 is greater than or equal to 53 degrees Celsius and less than 55 degrees Celsius, and the temperature range corresponding to the second coating region 115 is greater than or equal to 51 degrees Celsius and less than 53 degrees Celsius, etc. Other cases will not be listed here. In this case, the sixth coating region can be set as the reference coating region.

[0133] Optionally, based on the capacity change of each coating region, the coating region with the smallest capacity change is determined as the reference coating region. The coating parameters of other coating regions are adjusted according to the coating parameters of the reference coating region. This includes increasing the initial capacity of the first coating region 114 based on the difference between the capacity change of the first coating region 114 and the capacity change of the third coating region 116, and increasing the initial capacity of the second coating region 115 based on the difference between the capacity change of the second coating region 115 and the capacity change of the third coating region 116, so that the residual capacities of the first coating region 114, the second coating region 115, and the third coating region 116 are consistent. The third coating region 116 is the coating region with the smallest capacity change and is the reference coating region.

[0134] Among them, the coating area with the least capacity change is the area farthest from the first coating area 114, and the first coating area 114 is the area with the greatest capacity change. Therefore, it is necessary to adjust the coating parameters of each coating area according to the capacity change.

[0135] For example, after testing, the capacity change of the first coating region 114 is 5%, the capacity change of the second coating region 115 is 3%, and the capacity change of the third coating region 116 is 1%. When adjusting the coating parameters, the initial capacity of the first coating region 114 is increased by 4%, and the initial capacity of the second coating region 115 is increased by 2%. This makes the residual capacity of the first coating region 114, the second coating region 115, and the third coating region 116 after capacity decay basically the same, reducing the accelerated decay caused by the non-uniformity of the coating area, and effectively improving the cycle performance and service life of the battery cell 10.

[0136] The embodiments of this application increase the initial capacity of the first coating region 114 based on the difference between the capacity change of the first coating region 114 and the capacity change of the third coating region 116, and increase the initial capacity of the second coating region 115 based on the difference between the capacity change of the second coating region 115 and the capacity change of the third coating region 116, so that the residual capacity of the first coating region 114, the second coating region 115 and the third coating region 116 is consistent. This makes the residual capacity of the electrode coating area basically consistent in different regions, reducing the capacity decay of the battery cell 10.

[0137] Optionally, the capacity of the first coating region 114 can be increased by increasing the proportion of at least one high specific capacity material in the coating slurry of the first coating region 114, increasing the coating weight of the first coating region 114, and increasing the compaction density of the first coating region 114, wherein the specific capacity of the high specific capacity material is greater than 500 mAh / g.

[0138] It should be noted that the slurry formulation can contain two or more high-specific-capacity materials. In this case, it is only necessary to increase the proportion of one of the high-specific-capacity materials. Alternatively, the proportion of two or more high-specific-capacity materials can be increased simultaneously.

[0139] Specifically, increasing the initial capacity of the first coating region 114 can be achieved by increasing the proportion of at least one high specific capacity material in the formulation, increasing the coating weight of the first coating region 114, and increasing the compaction density of the first coating region 114, thereby increasing the initial capacity of the first coating region 114 through the combined effect of the two or three factors.

[0140] Alternatively, the initial capacity of the first coating region 114 can be increased by increasing the proportion of at least one high specific capacity material in the formulation, increasing the coating weight of the first coating region 114, or increasing the compaction density of the first coating region 114. The initial capacity of the first coating region 114 can be increased by changing only one parameter.

[0141] In the embodiments of this application, the initial capacity of the first coating region 114 is increased by increasing the proportion of high-capacity material in the formulation of the coating slurry of the first coating region 114, increasing the coating weight of the first coating region 114, and increasing the compaction density of the first coating region 114. This allows for convenient adjustment of the initial capacity of the first coating region 114 and increases the initial capacity of the first coating region 114.

[0142] In some embodiments of this application, the initial capacity of the second coating region 115 is increased by increasing the proportion of at least one high specific capacity material in the coating slurry of the second coating region 115, increasing the coating weight of the second coating region 115, and increasing the compaction density of the second coating region 115, wherein the specific capacity of the high specific capacity material is greater than 500 mAh / g.

[0143] Specifically, increasing the initial capacity of the second coating region 115 can be achieved by increasing the proportion of at least one high specific capacity material in the formulation, increasing the coating weight of the second coating region 115, and increasing the compaction density of the second coating region 115, thereby increasing the initial capacity of the second coating region 115 through the combined effect of the two or three factors.

[0144] Alternatively, the initial capacity of the second coating region 115 can be increased by increasing the proportion of at least one high specific capacity material in the formulation, increasing the coating weight of the second coating region 115, or increasing the compaction density of the second coating region 115. The initial capacity of the second coating region 115 can be increased by changing only one parameter.

[0145] In the embodiments of this application, the initial capacity of the second coating region 115 is increased by increasing the proportion of at least one high specific capacity material in the coating slurry of the second coating region 115, increasing the coating weight of the second coating region 115, and increasing the compaction density of the second coating region 115. This allows for convenient adjustment of the initial capacity of the second coating region 115 and increases the initial capacity of the second coating region 115.

[0146] For example, for the anode electrode, at least one high specific capacity material can be titanium dioxide, tin dioxide, or iron oxide, etc. Increasing the proportion of at least one high specific capacity material can improve the capacity. For the cathode electrode, nickel-cobalt-manganese ternary materials, low specific capacity cathode materials, high specific capacity cathode materials, binders, conductive agents, and plasticizers can be used. High specific capacity cathode materials can be lithium nickel-cobalt-manganese oxide and lithium nickel-cobalt-aluminum oxide, etc., while low specific capacity cathode materials include lithium iron phosphate and lithium manganese oxide, etc. Adjusting the proportions of these materials in the formulation can increase or decrease the capacity.

[0147] Optionally, based on the capacity change of each coating region, the coating region with the smallest capacity change is determined as the reference coating region. The coating parameters of other coating regions are adjusted according to the coating parameters of the reference coating region, including determining the electrode as a cathode electrode, reducing the capacity of the first coating region 114 based on the difference between the capacity change of the first coating region 114 and the capacity change of the third coating region 116, and reducing the initial capacity of the second coating region 115 based on the difference between the capacity change of the second coating region 115 and the capacity change of the third coating region 116, so that the residual capacities of the first coating region 114, the second coating region 115, and the third coating region 116 are consistent, wherein the third coating region 116 is the coating region with the smallest capacity change.

[0148] By reducing the initial capacity of the first coating region 114, it is more difficult for lithium ions to be embedded into the cathode electrode, so that the remaining charge of the cathode electrode after discharge in each region is basically the same.

[0149] The embodiments of this application reduce the initial capacity of the first coating region 114 based on the difference between the capacity change of the first coating region 114 and the capacity change of the third coating region 116, and reduce the initial capacity of the second coating region 115 based on the difference between the capacity change of the second coating region 115 and the capacity change of the third coating region 116, so that the residual capacity of the first coating region 114, the second coating region 115 and the third coating region 116 is consistent. This makes the residual capacity of the electrode coating area basically consistent in different regions, reducing the capacity decay of the battery cell 10.

[0150] In some embodiments of this application, the initial capacity of the first coating region 114 is reduced by increasing the proportion of at least one low specific capacity material in the coating slurry of the first coating region 114, reducing the coating weight of the first coating region 114, and reducing the compaction density of the first coating region 114, wherein the specific capacity of the low specific capacity material is less than or equal to 500 mAh / g.

[0151] It is important to emphasize that the slurry formulation can contain two or more low-specific-capacity materials. In this case, it is sufficient to increase the proportion of one of the low-specific-capacity materials. Alternatively, the proportion of two or more low-specific-capacity materials can be increased simultaneously.

[0152] It should be noted that the terms "low specific capacity material" and "high specific capacity material" are relative terms, and other data can also be used as distinguishing points, such as 450mAh / g or 300mAh / g.

[0153] In the embodiments of this application, the initial capacity of the first coating region 114 is reduced by increasing the proportion of at least one low specific capacity material in the coating slurry of the first coating region 114, reducing the coating weight of the first coating region 114, and reducing the compaction density of the first coating region 114. This allows for convenient adjustment of the initial capacity of the first coating region 114 and reduction of its initial capacity.

[0154] In some embodiments of this application, reducing the initial capacity of the second coating region 115 is achieved by increasing the proportion of at least one low specific capacity material in the coating slurry of the second coating region 115, reducing the coating weight of the second coating region 115, and reducing the compaction density of the second coating region 115.

[0155] In the embodiments of this application, reducing the initial capacity of the second coating region 115 can be achieved by increasing the proportion of at least one low specific capacity material in the coating slurry of the second coating region 115, reducing the coating weight of the second coating region 115, and reducing the compaction density of the second coating region 115. This allows for convenient adjustment of the initial capacity of the second coating region 115, thereby reducing the initial capacity of the second coating region 115, where the initial capacity is also the fresh capacity.

[0156] It should be noted that the reference coating area can be changed as needed. When there are only three coating areas, the reference coating area is the third coating area 116; when there are four coating areas, the reference coating area is the fourth coating area; and correspondingly, when there are five coating areas, the reference coating area is the fifth coating area. The coating parameters of the reference coating area include the formulation, coating weight, and compaction density, etc., and serve as the benchmark for the coating parameters of other coating areas. The coating parameters of the reference coating area can be determined using coating parameters from existing technologies.

[0157] Optionally, the temperature distribution of the coated area can be obtained by placing a temperature sensor on the surface of the coated area.

[0158] The embodiments of this application obtain the temperature distribution of the coating area by setting a temperature sensor on the surface of the coating area, which can realize accurate temperature measurement of the coating area and facilitate zoning according to the temperature range.

[0159] Optionally, such as Figure 6 and Figure 7 As shown, the preparation of the electrode according to the adjusted coating parameters of the coating area includes coating the electrode with a coating device 500, wherein the coating device 500 has multiple coating ports, and the multiple coating ports are arranged side by side along the width direction of the electrode.

[0160] The coating apparatus 500 here includes multiple coating systems, each capable of coating a coating area. Specifically, the coating apparatus 500 includes a first coating system 501, a second coating system 502, a third coating system 503, and a fourth coating system 504. The first coating system 501 includes a first coating channel 5011 and a first coating port 5012. The first coating port 5012 is used to spray a first slurry onto the substrate 600, forming a first slurry coating area 5013 on the substrate 600. The second coating system 502 includes a second coating channel 5021 and a second coating port 5022. The second coating port 5022 is used to spray a first slurry onto the substrate 600. The second slurry forms a second slurry coating area 5023 on the substrate 600. The third coating system 503 includes a third coating channel 5031 and a third coating port 5032. The third coating port 5032 is used to spray the third slurry onto the substrate 600 to form a third slurry coating area 5033 on the substrate 600. The fourth coating system 504 includes a fourth coating channel 5041 and a fourth coating port 5042. The fourth coating port 5042 is used to spray the fourth slurry onto the substrate 600 to form a fourth slurry coating area 5043 on the substrate 600.

[0161] It should be noted that the first coating system 501, the second coating system 502, the third coating system 503 and the fourth coating system 504 are formed into a target-shaped structure, and each coating system is used to spray different slurries.

[0162] The embodiments of this application employ a coating apparatus 500 to coat the electrode sheet. The coating apparatus 500 has multiple coating ports, which are arranged side by side along the width direction of the electrode sheet. This allows the electrode sheet to be coated sequentially through the multiple coating ports, thereby improving the coating efficiency of the electrode sheet.

[0163] After coating the electrode sheet, the battery cell 10 is produced through processes such as drying, cold pressing, winding, casing, liquid injection, and formation. The battery cell 10 is then tested to further improve the preparation method of the battery cell 10 and adjust the coating parameters of different coating areas.

[0164] The test results of the anode sheet of this application are further described in detail below with reference to Examples 1-5 and Comparative Example 1. However, it should be understood that the embodiments of this application are merely for explaining this application and are not intended to limit this application, and the embodiments of this application are not limited to the embodiments given in the specification. Unless otherwise specified, specific experimental or operating conditions in the embodiments were prepared under conventional conditions or according to the conditions recommended by the material supplier.

[0165] Example 1 can be operated according to the following steps: A substrate 600 with a thickness of 6μm is used, and five coating areas are provided on the coating area of ​​the substrate 600. The battery cell 10 is subjected to working condition simulation and two hundred charge-discharge cycles are performed to test the temperature distribution of the battery cell 10 and the retention ratio of the residual capacity of the battery cell 10 relative to the initial capacity, i.e., the 200cls capacity retention rate in Table 1. Among them, the initial capacity of the first coating area 114 is greater than the initial capacity of the second coating area 115, the initial capacity of the second coating area 115 is greater than the initial capacity of the third coating area 116, the initial capacity of the third coating area 116 is greater than the initial capacity of the fourth coating area, the initial capacity of the fourth coating area is greater than the initial capacity of the fifth coating area, and the 200cls capacity retention rate of the battery cell 10 is 87%.

[0166] Example 2 follows the same operating steps as Example 1, except that the initial capacity of each coating area is different from that in Example 1. Specifically, the first coating area 114 has the largest fresh capacity, and the 200cls capacity retention rate of the battery cell 10 is 92%.

[0167] Example 3 is the same as Example 1 in terms of operation steps, except that the initial capacity of each coating area is different from that in Example 1. The initial capacity of the first coating area 114 is the largest, and the 200cls capacity retention rate of the battery cell 10 is 88%.

[0168] Example 4 is the same as Example 1 in terms of operation steps, except that the initial capacity of each coating area is different from that in Example 1. The initial capacity of the first coating area 114 is the largest, and the 200cls capacity retention rate of the battery cell 10 is 85%.

[0169] Example 5 is the same as Example 1 in terms of operation steps, except that the initial capacity of each coating area is different from that in Example 1. The initial capacity of the first coating area 114 is the largest, and the 200cls capacity retention rate of the battery cell 10 is 83%.

[0170] Comparative Example 1 follows the same operating steps as Example 1 above, except that the initial capacity of the coating area is the same and the 200cls capacity retention rate of the battery cell 10 is 82%.

[0171] The evaluation structures of Examples 1-5 and Comparative Example 1 are shown in Table 1 below.

[0172] Table 1. Comparison of test results for anode plates

[0173]

[0174] The experimental results of the cathode electrode of this application are further described in detail below with reference to Examples 6-10 and Comparative Example 2. However, it should be understood that the embodiments of this application are merely for explaining this application and are not intended to limit this application, and the embodiments of this application are not limited to the embodiments given in the specification. Unless otherwise specified, specific experimental or operating conditions in the embodiments were prepared under conventional conditions or according to the conditions recommended by the material supplier.

[0175] Example 6 can be operated according to the following steps: A substrate 600 with a thickness of 6μm is used, and five coating areas are provided on the coating area of ​​the substrate 600. The battery cell 10 is subjected to working condition simulation and two hundred charge-discharge cycles are performed to test the temperature distribution of the battery cell 10 and the retention ratio of the residual capacity of the battery cell 10 relative to the initial capacity, i.e., the 200 cl capacity retention rate in Table 1. The initial capacity of the first coating area 114 is less than the initial capacity of the second coating area 115, the initial capacity of the second coating area 115 is less than the initial capacity of the third coating area 116, the initial capacity of the third coating area 116 is less than the initial capacity of the fourth coating area, and the initial capacity of the fourth coating area is less than the initial capacity of the fifth coating area. The 200 cl capacity retention rate of the battery cell 10 is 87%.

[0176] Example 7 follows the same operating steps as Example 1, except that the initial capacity of each coating region is different from that in Example 1. Specifically, the initial capacity of the first coating region 114 is the smallest, and the 200 cl capacity retention rate of the battery cell 10 is 92%.

[0177] Example 8 is the same as Example 1 in terms of operation steps, except that the initial capacity of each coating area is different from that in Example 1. The initial capacity of the first coating area 114 is the smallest, and the 200 cl capacity retention rate of the battery cell 10 is 88%.

[0178] Example 9 is the same as Example 1 in terms of operation steps, except that the initial capacity of each coating area is different from that in Example 1. The initial capacity of the first coating area 114 is the smallest, and the 200 cl capacity retention rate of the battery cell 10 is 85%.

[0179] Example 10 is the same as Example 1 in terms of operation steps, except that the initial capacity of each coating area is different from that in Example 1. The initial capacity of the first coating area 114 is the smallest, and the 200 cl capacity retention rate of the battery cell 10 is 83%.

[0180] Comparative Example 2 follows the same operating steps as Example 7 above, except that the initial capacity of the coating area is the same, and the 200 cl capacity retention rate of the battery cell 10 is 82%.

[0181] The test results of Examples 6-10 and Comparative Example 2 are shown in Table 2.

[0182] Table 2. Comparison of test results for cathode electrodes

[0183]

[0184] As can be seen from the results above, in this embodiment, the electrode can improve the capacity retention of the battery cell 10 by coating the electrode area in sections, thereby improving the service life of the battery cell 10.

[0185] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application.

[0186] A first aspect of this application provides a method for preparing an electrode sheet, wherein the electrode sheet has a coating area and is applied to a battery cell 10. The method includes: acquiring the temperature distribution of the coating area of ​​the battery cell 10 in a test state; acquiring at least one test temperature value of the coating area of ​​the battery cell 10 in the test state; dividing the coating area into multiple coating regions based on the test temperature values; determining the capacity change of the coating region based on the capacity distribution of the coating region; determining the coating region with the smallest capacity change as a reference coating region based on the capacity change of each coating region; adjusting the coating parameters of other coating regions based on the coating parameters of the reference coating region; and preparing the electrode sheet according to the adjusted coating parameters of the coating region. Further, the coating parameters include at least one of the following: coating slurry formulation, compaction density, and coating weight. Further, determining the capacity change of the coating region based on the capacity distribution of the coating region specifically includes acquiring the difference between the initial capacity and the residual capacity of the coating region to determine the capacity change of the coating region. Further, based on the temperature distribution of the coating area, the coating area is divided into multiple coating regions, including extending from the middle region of the coating area to both sides along the width direction of the electrode, and dividing the coating regions according to the temperature range, wherein the middle region is the region with the highest average temperature. Further, extending from the middle region of the coating area to both sides along the width direction of the electrode, and dividing the coating regions according to the temperature range, includes determining the region with the highest average temperature as the first coating region 114; extending from the region with the highest average temperature to both sides along the width direction of the electrode, the region with a temperature within the first range is the second coating region 115, and the average temperature of the first range is lower than the average temperature of the region with the highest average temperature. Further, extending from the middle region of the coating area to both sides along the width direction of the electrode, and dividing the coating regions according to the temperature range, also includes extending from the second coating region 115 in a direction away from the region with the highest average temperature, the region with a temperature within the second range is the third coating region 116, and the average temperature of the second range is lower than the average temperature of the first range. Furthermore, based on the capacity change of each coating region, the coating region with the smallest capacity change is determined as the reference coating region. The coating parameters of other coating regions are adjusted according to the coating parameters of the reference coating region. This includes increasing the initial capacity of the first coating region 114 based on the difference between the capacity change of the first coating region 114 and the capacity change of the third coating region 116, and increasing the initial capacity of the second coating region 115 based on the difference between the capacity change of the second coating region 115 and the capacity change of the third coating region 116, so that the residual capacities of the first coating region 114, the second coating region 115, and the third coating region 116 are consistent.Further, increasing the initial capacity of the first coating region 114 is achieved by increasing the proportion of at least one high specific capacity material in the coating slurry of the first coating region 114, increasing the coating weight of the first coating region 114, and increasing the compaction density of the first coating region 114, wherein the specific capacity of the high specific capacity material is greater than 500 mAh / g. Further, increasing the initial capacity of the second coating region 115 is achieved by increasing the proportion of at least one high specific capacity material in the coating slurry of the second coating region 115, increasing the coating weight of the second coating region 115, and increasing the compaction density of the second coating region 115, wherein the specific capacity of the high specific capacity material is greater than 500 mAh / g. Furthermore, based on the capacity change of each coating region, the coating region with the smallest capacity change is determined as the reference coating region. The coating parameters of other coating regions are adjusted according to the coating parameters of the reference coating region, including determining the electrode as the cathode electrode, reducing the capacity of the first coating region 114 based on the difference between the capacity change of the first coating region 114 and the capacity change of the third coating region 116, and reducing the capacity of the second coating region 115 based on the difference between the capacity change of the second coating region 115 and the capacity change of the third coating region 116, so that the residual capacities of the first coating region 114, the second coating region 115, and the third coating region 116 are consistent, wherein the third coating region 116 is the coating region with the smallest capacity change. Further, the initial capacity of the first coating region 114 is reduced by at least one of increasing the proportion of at least one low-specific-capacity material in the coating slurry of the first coating region 114, reducing the coating weight of the first coating region 114, and reducing the compaction density of the first coating region 114, wherein the specific capacity of the low-specific-capacity material is less than or equal to 500 mAh / g. Further, the initial capacity of the second coating region 115 is reduced by at least one of increasing the proportion of at least one low-specific-capacity material in the coating slurry of the second coating region 115, reducing the coating weight of the second coating region 115, and reducing the compaction density of the second coating region 115, wherein the specific capacity of the low-specific-capacity material is less than or equal to 500 mAh / g. Further, the temperature distribution of the coating region is obtained by setting a temperature sensor on the surface of the coating region. Further, the capacity change of the coating region is determined based on the capacity distribution of the coating region by conducting a discharge test on a coin cell made from disassembled electrode sheets. Furthermore, the preparation of the electrode according to the coating parameters of the adjusted coating area includes coating the electrode with a coating device 500, wherein the coating device 500 has multiple coating ports, and the multiple coating ports are arranged side by side along the width direction of the electrode.

[0187] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing an electrode, wherein the electrode has a coating area, and the electrode is applied to a battery cell, characterized in that, The preparation method includes: Obtain at least one test temperature value of the coating area of ​​the battery cell in the test state, and divide the coating area into multiple coating regions according to the test temperature value; Obtain the capacity distribution of the coated area of ​​the battery cell under the test state, and determine the capacity change of the coated area based on the capacity distribution of the coated area; Based on the capacity change of each coating region, the coating region with the smallest capacity change is determined as the reference coating region, and the coating parameters of the other coating regions are adjusted according to the coating parameters of the reference coating region. The electrode is prepared according to the adjusted coating parameters of the coating area.

2. The method for preparing the electrode as described in claim 1, characterized in that, The coating parameters include at least one of the following: coating slurry formulation, compaction density, and coating weight.

3. The method for preparing the electrode as described in claim 1, characterized in that, Determining the capacity change of the coating area based on the capacity distribution of the coating area specifically includes: The difference between the initial capacity of the coated area and the residual capacity of the coated area is obtained to determine the amount of capacity change of the coated area.

4. The method for preparing the electrode sheet as described in claim 1, characterized in that, The coating area is divided into multiple coating regions based on the test temperature value, including: The coating area extends from the middle region to both sides along the width direction of the electrode sheet, and the coating area is divided according to the temperature range, wherein the middle region is the region with the highest average temperature.

5. The method for preparing the electrode sheet as described in claim 4, characterized in that, Extending from the center of the coating area to both sides along the width direction of the electrode sheet, the coating area is divided according to the temperature range, including: The region with the highest average temperature is defined as the first coating region; The area extending from the center to both sides along the width direction of the electrode sheet, where the temperature falls within the first temperature range, is the second coating area, and the average temperature of the first temperature range is lower than the average temperature of the area with the highest average temperature.

6. The method for preparing the electrode sheet as described in claim 5, characterized in that, Extending from the center of the coating area to both sides along the width direction of the electrode sheet, the coating area is further divided according to the temperature range: Along the width direction of the electrode, extending from the second coating area away from the area with the highest average temperature, the area with a temperature in the second interval range is the third coating area, and the average temperature of the second interval range is lower than the average temperature of the first interval range.

7. The method for preparing the electrode sheet as described in claim 6, characterized in that, Based on the capacity change of each coating region, the coating region with the smallest capacity change is determined as the reference coating region. Adjusting the coating parameters of the other coating regions based on the coating parameters of the reference coating region includes: The electrode is determined to be an anode electrode. Based on the difference between the capacity change in the first coating region and the capacity change in the third coating region, the initial capacity of the first coating region is increased. Based on the difference between the capacity change in the second coating region and the capacity change in the third coating region, the initial capacity of the second coating region is increased. This ensures that the residual capacities of the first coating region, the second coating region, and the third coating region are consistent. The third coating region is the coating region with the smallest capacity change and is the reference coating region.

8. The method for preparing the electrode sheet as described in claim 7, characterized in that, The initial capacity of the first coating region is increased by increasing the proportion of at least one high specific capacity material in the coating slurry of the first coating region, increasing the coating weight of the first coating region, and increasing the compaction density of the first coating region, wherein the specific capacity of the high specific capacity material is greater than 500 mAh / g.

9. The method for preparing the electrode sheet as described in claim 7, characterized in that, The initial capacity of the second coating region is increased by increasing the proportion of at least one high specific capacity material in the coating slurry of the second coating region, increasing the coating weight of the second coating region, and increasing the compaction density of the second coating region, wherein the specific capacity of the high specific capacity material is greater than 500 mAh / g.

10. The method for preparing the electrode sheet as described in claim 6, characterized in that, Based on the capacity change of each coating region, the coating region with the smallest capacity change is determined as the reference coating region. Adjusting the coating parameters of the other coating regions based on the coating parameters of the reference coating region includes: The electrode is determined to be a cathode electrode. Based on the difference between the capacity change in the first coating region and the capacity change in the third coating region, the initial capacity of the first coating region is reduced. Similarly, based on the difference between the capacity change in the second coating region and the capacity change in the third coating region, the initial capacity of the second coating region is reduced. This ensures that the residual capacities of the first, second, and third coating regions are consistent. The third coating region is the coating region with the least capacity change and serves as the reference coating region.

11. The method for preparing the electrode sheet as described in claim 10, characterized in that, The initial capacity of the first coating region is reduced by increasing the proportion of at least one low specific capacity material in the coating slurry of the first coating region, reducing the coating weight of the first coating region, and reducing the compaction density of the first coating region, wherein the specific capacity of the low specific capacity material is less than or equal to 500 mAh / g.

12. The method for preparing the electrode sheet as described in claim 10, characterized in that, The reduction of the initial capacity of the second coating region is achieved by increasing the proportion of at least one low specific capacity material in the coating slurry of the second coating region, reducing the coating weight of the second coating region, and reducing the compaction density of the second coating region, wherein the specific capacity of the low specific capacity material is less than or equal to 500 mAh / g.

13. The method for preparing the electrode sheet according to any one of claims 1 to 12, characterized in that, The temperature distribution of the coated area is obtained by placing a temperature sensor on the surface of the coated area.

14. The method for preparing the electrode sheet according to any one of claims 1 to 12, characterized in that, The capacity change of the coating area is determined based on the capacity distribution of the coating area by conducting a discharge test on the disassembled electrode sheets after they are made into coin cells.

15. The method for preparing the electrode sheet according to any one of claims 4 to 12, characterized in that, The electrode is prepared according to the adjusted coating parameters of the coating area, including: The electrode is coated using a coating device, wherein the coating device has multiple coating ports, and the multiple coating ports are arranged side by side along the width direction of the electrode.

16. A battery cell comprising an electrode prepared by the method of any one of claims 1 to 15.

17. A battery device, characterized in that, include: Battery housing: and The battery cell as described in claim 16 is disposed within the battery casing.

18. An electrical appliance, characterized in that, Includes the battery device as described in claim 17, the battery device being used to store or provide electrical energy.

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