Battery cell, battery device and electric device

Abstract

A battery cell, a battery device and an electric device. The battery cell comprises a casing, an electrode assembly and electrode terminals, wherein the electrode assembly is accommodated in the casing, and the electrode terminals are arranged on the housing. The electrode assembly comprises a first electrode sheet and a second electrode sheet. The first electrode sheet and the second electrode sheet each comprise an electrode sheet body and at least one tab portion, wherein at least part of the electrode sheet body is provided with an active material layer, at least part of the tab portion is provided with no active material layer, the electrode sheet body and the tab portion are arranged in a first direction, and the size of the tab portion in a second direction is less than or equal to the size of the electrode sheet body in the second direction; and the tab portion is electrically connected to an electrode terminal. The first electrode sheet satisfies the condition: the maximum value of a2+b2 ranges from 6000 to 110000, wherein a represents the distance between any point A of the electrode sheet body and the tab portion closest to the point A among all the tab portions in the first direction, with the unit of a being mm; and b represents the distance between the point A and the tab portion closest to the point A among all the tab portions in the second direction, with the unit of b being mm.

Description

Battery cells, battery packs and electrical devices

[0001] Cross-references to related applications

[0002] This application claims priority to international patent application PCT / CN2025 / 071119, filed on January 7, 2025, entitled “Battery Cell, Battery Device and Electrical Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, and more specifically, to a battery cell, a battery device, and an electrical device. Background Technology

[0004] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0005] In the development of battery technology, improving the performance of individual battery cells is a key research direction. Summary of the Invention

[0006] This application provides a battery cell, a battery device, and an electrical device that can improve the performance of the battery cell.

[0007] In a first aspect, embodiments of this application provide a battery cell, including a casing, an electrode assembly, and electrode terminals. At least a portion of the electrode assembly is housed within the casing, and the electrode terminals are disposed within the casing. The electrode assembly includes a first electrode and a second electrode, one of which is a positive electrode and the other a negative electrode. Both the first and second electrode include an electrode body and at least one tab. At least a portion of the electrode body has an active material layer, and at least a portion of the tab does not have an active material layer. The electrode body and the tab are arranged along a first direction, and the dimension of the tab along a second direction is less than or equal to the dimension of the electrode body along the second direction. The first direction, the second direction, and the thickness direction of the electrode body are perpendicular to each other. The tab is electrically connected to the electrode terminals. The first electrode satisfies: a 2 +b 2 The maximum value is 6000 to 110000; where a represents the distance along the first direction between any point A of the electrode body and the electrode tab closest to point A among all electrode tabs in the first electrode, and the unit of a is mm; b represents the distance along the second direction between point A of the first electrode and the electrode tab closest to point A among all electrode tabs, and the unit of b is mm.

[0008] In this embodiment of the application, a 2 +b 2Setting the maximum value to greater than or equal to 6000 allows the electrode body to have a larger area, which is beneficial for increasing the capacity and energy density of the battery cell. Setting a... 2 +b 2 Setting the maximum value to less than or equal to 110000 can reduce the maximum electron transport path in the electrode, making the electron transport path relatively short, thereby reducing the internal resistance of the battery cell, reducing the heat generated by the battery cell during charging, and helping to improve the cycle performance and fast charging performance of the battery cell.

[0009] In some embodiments, the dimension of the electrode body along the first direction is greater than the dimension of the electrode body along the second direction.

[0010] In some embodiments, the first electrode has multiple tabs, which are respectively disposed on both sides of the electrode body along the first direction. Compared with the size of the electrode body along the second direction, the size of the electrode body along the first direction is larger; by disposing multiple tabs on both sides of the electrode body along the first direction, the maximum value of 'a' can be reduced, thereby shortening the electron transport path in the first electrode and improving fast charging performance.

[0011] In some embodiments, the electrode body has a dimension of 320 mm to 650 mm along the first direction. In this application embodiment, setting L4 to be greater than or equal to 320 mm increases the capacity of a single battery cell, which is beneficial for reducing the number of battery cells in the battery device and improving the energy density of the battery device. In this application embodiment, setting L4 to be less than or equal to 650 mm makes the electron transport path of the electrode relatively short in the first direction, thereby reducing the internal resistance of the battery cell, reducing heat generation during charging, and improving the cycle performance and fast charging performance of the battery cell.

[0012] In some embodiments, the first electrode satisfies: a 2 +b 2 The maximum value is between 25,600 and 110,000; optionally, a 2 +b 2 The maximum value is between 25,600 and 90,000. The embodiments of this application can further balance the energy density and fast-charging performance of individual battery cells.

[0013] In some embodiments, the dimension of the electrode body along the first direction is smaller than the dimension of the electrode body along the second direction.

[0014] In some embodiments, the first electrode has multiple tabs, all of which are located on the same side of the electrode body along a first direction. By providing multiple tabs, the current-carrying area can be increased, the electron transport path of the electrode body can be shortened, thereby reducing the internal resistance of the battery cell. By locating all the tabs of the first electrode on the same side of the electrode body along the first direction, the total space occupied by the tabs in the first direction can be reduced, providing more space for the electrode body, improving space utilization, and increasing the energy density of the battery cell.

[0015] In some embodiments, the electrode body has a dimension of 50mm-200mm along the first direction; optionally, the electrode body has a dimension of 80mm-150mm along the first direction. In this application embodiment, L4 is set to be greater than or equal to 50mm to increase the capacity and energy density of the battery cell. Setting L4 to be less than or equal to 200mm can reduce the maximum value of 'a', thereby reducing the internal resistance of the battery cell, reducing heat generation during charging, and improving the cycle performance and fast charging performance of the battery cell.

[0016] In some embodiments, the first electrode satisfies: a 2 +b 2 The maximum value is 6400 to 45000; optionally, a 2 +b 2 The maximum value is 6400 to 25000. The embodiments of this application can further balance the energy density and fast charging performance of individual battery cells.

[0017] In some embodiments, the first electrode has multiple tabs disposed on the same side of the electrode body, and the distance D1 between two adjacent tabs along the second direction is greater than 0 and less than or equal to 300 mm. In this embodiment, D1 is set to be greater than 0 to reduce the influence between adjacent tabs when bending them, thus reducing the difficulty of bending the tabs. Setting D1 to less than or equal to 300 mm helps to reduce the maximum value of b, thereby making the electron transport path relatively short, reducing the internal resistance of the battery cell, reducing heat generation during charging, and improving the cycle performance and fast charging performance of the battery cell.

[0018] In some embodiments, the sum of the dimensions of all tabs located on the same side of the electrode body along the second direction is W1, and the dimension of the electrode body along the second direction is W2. The first electrode satisfies that W1 / W2 is 0.5 to 1.0. Setting W1 / W2 to 0.5 to 1.0 in this embodiment allows for a relatively large connection area between the tab and the electrode body, and also a relatively large current-carrying area for the tab. This is beneficial for reducing DC resistance, reducing heat generation, and improving the fast-charging performance of the battery cell.

[0019] In some embodiments, the electrode body includes a current collector, and at least a portion of the active material layer is disposed on the surface of the current collector. The current collector includes a first current collector region and a second current collector region arranged along a second direction, and an electrode tab extends from the end of the second current collector region along a first direction. The dimension of the first current collector region along the second direction is L1, and the dimension of the second current collector region along the second direction is L2. 2≤L1 / L2≤30.

[0020] Compared to the first current collector, the second current collector is closer to the tab; the longest transmission path of the first current collector is longer than that of the second current collector. In this embodiment, L1 / L2 is set to be greater than or equal to 2 to increase the area of ​​the first current collector or decrease the area of ​​the second current collector. Increasing the area of ​​the first current collector can improve the capacity of the electrode body, while decreasing the area of ​​the second current collector can reduce the size of the tab along the second direction, reducing the space occupied by the tab and the difficulty of bending it. In this embodiment, L1 / L2 is set to be less than or equal to 30 to limit the magnitude of the increase in the area of ​​the first current collector or the magnitude of the decrease in the area of ​​the second current collector. Limiting the magnitude of the increase in the area of ​​the first current collector can reduce the maximum value of b, shortening the longest transmission path of the first current collector; limiting the magnitude of the decrease in the area of ​​the second current collector can ensure that the current-carrying area of ​​the tab meets the requirements of fast charging.

[0021] In some embodiments, 6 ≤ L1 / L2 ≤ 20.

[0022] In some embodiments, the electrode body includes a current collector, and at least a portion of the active material layer is disposed on the surface of the current collector. The current collector includes a first current collector region and a second current collector region arranged along a second direction, and an electrode tab extends from the end of the second current collector region along a first direction. The dimension of the first current collector region along the second direction is L1, and the dimension of the first current collector region along the first direction is L3. 0.1≤L3 / L1≤5.

[0023] In this embodiment, L3 / L1 is set to 0.1-5, which can reduce a while given a fixed area of ​​the first current collection zone. 2 +b 2 The maximum value of this property results in a relatively short electron transport path, thereby reducing the internal resistance of the battery cell.

[0024] In some embodiments, 0.5 ≤ L3 / L1 ≤ 2.

[0025] In some embodiments, the current collector includes a plurality of first current collector regions and a plurality of second current collector regions, which are alternately arranged along a second direction. Each second current collector region is connected to at least one electrode tab. By providing a plurality of first current collector regions and a plurality of second current collector regions, the electron transport path can be relatively short, effectively reducing the internal resistance of the battery cell. Furthermore, each electrode tab carries a smaller current, resulting in a more uniform current distribution, which is beneficial for the rapid charging of the battery cell.

[0026] In some embodiments, the electrode body of the first electrode includes a coating region and a transition region arranged along a first direction. An active material layer is disposed in the coating region, while neither the transition region nor the tab is provided with an active material layer. The transition region connects the coating region and the tab. The first electrode also includes an insulating member, at least a portion of which is disposed in the transition region. By providing the insulating member, the risk of burrs on the electrode body of the second electrode becoming conductive with the first electrode can be reduced.

[0027] In some embodiments, the second electrode satisfies: e 2 +f 2 The maximum value is 6000 to 110000; where e represents the distance along the first direction between any point B on the electrode body and the tab closest to point B among all the tabs in the second electrode, and the unit of e is mm; f represents the distance along the second direction between point B and the tab closest to point B among all the tabs in the second electrode, and the unit of f is mm. When the second electrode in the embodiments of this application satisfies the above conditions, the electron transport path is relatively short, which can effectively reduce the internal resistance of the battery cell and make the current distribution more uniform, thereby facilitating the rapid charging of the battery cell.

[0028] In some embodiments, the active material layer of the positive electrode sheet comprises a lithium phosphate with an olivine structure. Using a lithium phosphate with an olivine structure is beneficial for improving the reliability of the battery cell, extending its lifespan, and improving its high-temperature performance. This application embodiment will use a... 2 +b 2 Setting the maximum value to 6000 to 110000 can make the electron transport path in the electrode relatively short, reduce the impact of lithium phosphate with olivine structure on internal resistance, and improve the fast charging performance of the battery cell.

[0029] In some embodiments, the active material layer of the negative electrode comprises a carbon-based material. Carbon-based materials have high cycle stability, which can improve the cycle performance of the battery cell.

[0030] In some embodiments, the negative electrode sheet includes a current collector and an active material layer. The current collector is a negative electrode current collector, and the active material layer is a negative electrode active material layer. The negative electrode active material layer includes a first negative electrode film layer and a second negative electrode film layer. The first negative electrode film layer is disposed on the surface of the negative electrode current collector, and the second negative electrode film layer is disposed on the side of the first negative electrode film layer opposite to the negative electrode current collector. The volume average particle size Dv50 of the carbon-based material in the first negative electrode film layer is greater than or equal to the volume average particle size Dv50 of the carbon-based material in the second negative electrode film layer. Layering the active material layers helps to improve the fast charging performance of the battery cell.

[0031] In some embodiments, the electrode assembly includes multiple tab groups of the same polarity, each tab group including at least two stacked tab portions. The battery cell includes an adapter connected to the electrode terminals, the adapter being connected to the multiple tab groups. The same adapter can connect multiple tab groups of the same polarity to the electrode terminals, facilitating current convergence and simplifying the battery cell structure.

[0032] In some embodiments, a plurality of tabs are disposed on the same side of the electrode assembly along a first direction, and the adapter includes a first adapter portion and a second adapter portion connected to each other, the first adapter portion being connected to the plurality of tabs and the second adapter portion being connected to the electrode terminals.

[0033] In some embodiments, a plurality of tabs are respectively disposed on both sides of the electrode assembly along a first direction. The adapter includes two first adapter portions and a second adapter portion. The second adapter portion is connected to the electrode terminal. The two first adapter portions are respectively connected to the two ends of the second adapter portion along the first direction. Each first adapter portion is connected to at least one tab group.

[0034] In some embodiments, the battery cell is a prismatic battery cell. Along the length of the battery cell, the electrode body has a size of 320mm to 650mm, with a first direction parallel to either the length or width of the battery cell. In this embodiment, setting the electrode body size to be greater than or equal to 320mm increases the capacity of a single battery cell, which is beneficial for reducing the number of battery cells in the battery device and improving the energy density of the battery device. In this embodiment, setting the electrode body size to be less than or equal to 650mm shortens the electron transport path along the length of the battery cell, thereby reducing the internal resistance of the battery cell, reducing heat generation during charging, and improving the cycle performance and fast-charging performance of the battery cell.

[0035] In some embodiments, the battery cell is a cylindrical battery cell, with the first direction parallel to the axial direction of the battery cell. Cylindrical battery cells have advantages such as mature manufacturing process, good consistency, good heat dissipation performance, and high assembly efficiency.

[0036] In some embodiments, the housing includes a first end wall, a second end wall, and a side wall. The first end wall and the second end wall are disposed along a first direction, and the side wall connects the first end wall and the second end wall. Electrode terminals are insulated from the first end wall. One of the tabs of the first electrode and the tabs of the second electrode is electrically connected to the first end wall, and the other is electrically connected to the electrode terminal. The first end wall and the electrode terminal can serve as two electrodes of a single battery cell and are located on the same side of the battery cell. When multiple battery cells are assembled into a group, it facilitates the connection of the busbar to the first end wall or the connection of the busbar to the electrode terminal, simplifying the structure of the battery device.

[0037] In some embodiments, the sidewall has an inwardly protruding portion, and the battery cell further includes an adapter located on one side of the electrode assembly along a first direction and connected to the protrusion. One of the tabs of the first electrode and the second electrode is disposed at the end of the electrode assembly facing the adapter and connected to the adapter. Connecting the adapter to the protrusion shortens the conductive path between the first endwall and the tab, reduces resistance, reduces heat generation, and improves the cycle performance of the battery cell.

[0038] Secondly, embodiments of this application provide a battery device including a plurality of battery cells provided in any of the embodiments of the first aspect.

[0039] Thirdly, embodiments of this application provide an electrical device, including the battery device provided in any of the embodiments of the second aspect, the battery device being used to provide electrical energy. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0041] Figure 1 is a schematic diagram of the vehicle structure provided in some embodiments of this application;

[0042] Figure 2 is a schematic diagram of a battery device provided in some embodiments of this application;

[0043] Figure 3 is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0044] Figure 4 is a cross-sectional schematic diagram of a battery cell provided in some embodiments of this application;

[0045] Figure 5 is a schematic diagram of the electrode assembly of a battery cell provided in some embodiments of this application;

[0046] Figure 6 is a cross-sectional view of Figure 5 along the K1-K1 direction;

[0047] Figure 7 is a schematic diagram of the electrode sheets of a battery cell provided in some embodiments of this application;

[0048] Figure 8 is a cross-sectional view of Figure 7 along the K2-K2 direction;

[0049] Figure 9 is another schematic diagram of the electrode shown in Figure 7, in which the active material layer is omitted;

[0050] Figure 10 is a schematic diagram of the first electrode of a battery cell provided in some other embodiments of this application;

[0051] Figure 11 is a schematic diagram of the first electrode provided in some other embodiments of this application;

[0052] Figure 12 is a schematic diagram of the first electrode provided in some other embodiments of this application;

[0053] Figure 13 is a schematic diagram of the first electrode provided in some other embodiments of this application;

[0054] Figure 14 is a schematic diagram of the first electrode provided in some other embodiments of this application;

[0055] Figure 15 is a schematic diagram of the second electrode provided in some embodiments of this application;

[0056] Figure 16 is a cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application;

[0057] Figure 17 is a cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application;

[0058] Figure 18 is a cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application;

[0059] Figure 19 is a schematic diagram of the first electrode provided in some other embodiments of this application;

[0060] Figure 20 is a cross-sectional view of Figure 19 along the K3-K3 direction;

[0061] Figure 21 is a cross-sectional schematic diagram of the negative electrode sheet of a battery cell provided in some embodiments of this application;

[0062] Figure 22 is an exploded schematic diagram of a battery cell provided in some other embodiments of this application;

[0063] Figure 23 is a schematic diagram of the electrode of a battery cell in an unfolded state according to some embodiments of this application;

[0064] Figure 24 is a partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application.

[0065] The reference numerals in the attached drawings are explained as follows: 1. Vehicle; 2. Battery unit; 3. Controller; 4. Motor; 5. Housing; 5a. First housing; 5b. Second housing; 6. Battery module; 7. Battery cell; 10. Electrode assembly; 11. First electrode; 12. Second electrode; 13. Positive electrode; 14. Negative electrode; 15. Electrode body; 151. Active material layer; 1511. First negative electrode film layer; 1512. Second negative electrode film layer; 151a. Positive active material layer; 151b. Negative active material layer; 152. Current collector; 1521. First current collector area; 1522. Second current collector area; 152a. First current collector; 152b. Second current collector; 152c. Positive current collector; 152d. Negative current collector; 153. Coating area; 154. Transition area; 5a. First electrode body; 15b. Second electrode body; 15c. Positive electrode body; 15d. Negative electrode body; 16. Electrode tab; 161. First end; 162. Second end; 16a. First electrode tab; 16b. Second electrode tab; 16c. Positive electrode tab; 16d. Negative electrode tab; 17. Isolator; 18. Electrode tab assembly; 18. For; 18a. First electrode tab assembly; 18b. Second electrode tab assembly; 19. Insulating component; 20. Outer shell; 20a. Second end wall; 21. Shell; 211. First end wall; 212. Side wall; 2121. Protrusion; 2122. Recess; 2123. Press-fit part; 212a. First shell wall; 212b. Second shell wall; 212c. Third shell wall; 212d. First sub-wall; 212e. Second sub-wall; 22. End cap; 30. Electrode terminal; 30a. First electrode terminal; 30b. Second electrode terminal; 40. Adapter; 40a. First adapter; 40b. Second adapter; 41. First adapter part; 42. Second adapter part; 50. Conductive element; 50a. First conductive element; 50b. Second conductive element; 51. First conductive part; 52. Second conductive part; Z1. Thickness direction of battery cell; Z2. Length direction of battery cell; Z3. Width direction of battery cell; X, first direction; Y, second direction; T, thickness direction of the electrode body. Detailed Implementation

[0066] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the battery cell, battery device, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0067] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, it is also expected that ranges of 60 to 110 and 80 to 120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise stated, the numerical range "a to b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 and 5" have been listed in this article; "0 to 5" is just a shortened representation of these numerical combinations. In addition, when a parameter is stated as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0068] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined with each other to form new technical solutions.

[0069] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0070] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0071] In this application, "multiple" means two or more (including two).

[0072] In this embodiment of the application, the battery cell can be a secondary battery cell, which refers to a battery cell that can be used again after being discharged by recharging to activate the active materials.

[0073] A battery cell includes an electrode assembly, which in turn includes electrode plates. During charging, electrons travel within the electrode plates. If the electron travel path is too long, the electronic conductivity is low and the internal resistance is high, which is detrimental to the rapid charging of the battery cell. This is especially true at high energy densities, where the internal resistance further increases, hindering rapid charging at high energy densities.

[0074] In view of this, the present application provides a technical solution that, by designing the electron transmission distance, can to a certain extent balance the energy density and overcurrent capacity of a battery cell, thereby improving the cycle performance of the battery cell.

[0075] The battery cells described in this application are applicable to battery devices and electrical devices that use battery devices. Electrical devices can be equipment that uses battery devices as a power source or various energy storage systems that use battery devices as energy storage elements. Electrical devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0076] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0077] Figure 1 is a schematic diagram of the structure of a vehicle provided in some embodiments of this application.

[0078] As shown in Figure 1, a battery device 2 is installed inside the vehicle 1. The battery device 2 can be located at the bottom, front, or rear of the vehicle 1. The battery device 2 can be used to power the vehicle 1; for example, the battery device 2 can serve as the operating power source for the vehicle 1.

[0079] The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0080] In some embodiments of this application, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0081] Figure 2 is a schematic diagram of a battery device provided in some embodiments of this application.

[0082] In some embodiments, the battery device 2 may include one or more battery cell assemblies for providing voltage and capacity.

[0083] A battery cell assembly may include multiple battery cells 7, which are connected in series, parallel, or mixed connection via a busbar. Mixed connection means that multiple battery cells 7 are connected in both series and parallel.

[0084] The battery cell 7 can be a secondary battery cell, which refers to a battery cell that can be recharged after being discharged to activate the active materials and continue to be used.

[0085] As an example, the battery cell 7 can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-metal hydride battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc.

[0086] As an example, the battery cell 7 can be a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include square battery cells, blade-shaped battery cells, and multi-prismatic battery cells, such as hexagonal prismatic battery cells.

[0087] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells 7; as an example, a battery cell assembly can be a battery module 6, which is formed by arranging and fixing multiple battery cells to form an independent module. As an example, a battery module 6 can be formed by bundling multiple battery cells together with cable ties.

[0088] In some embodiments, the battery device 2 may be a battery pack, which includes a housing 5 and one or more battery cell assemblies housed within the housing 5. As an example, the battery cell assembly may be a battery module 6, which can be housed within the housing by securing the battery module 6 to the housing. Alternatively, the battery cell assembly may be housed within the housing by directly securing multiple battery cells to the housing.

[0089] In some embodiments, the housing 5 is used to house individual battery cells, and the housing 5 can have various structures.

[0090] In some embodiments, the housing 5 may include a first housing 5a and a second housing 5b. The first housing 5a and the second housing 5b are fastened together to form a closed space inside the housing 5 to house the battery cell assembly. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first housing may be a top cover or a bottom plate.

[0091] In some embodiments, the housing 5 may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are respectively connected to the frame, forming an enclosed space inside the housing to accommodate individual battery cells. As an example, the frame may include multiple side beams.

[0092] In some embodiments, the housing 5 may be part of the vehicle's chassis structure. For example, a portion of the housing 5 may be at least a portion of the vehicle's floor, or a portion of the housing 5 may be at least a portion of the vehicle's crossbeams and longitudinal beams.

[0093] In some embodiments, the battery device 2 may be an energy storage device.

[0094] Energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, energy storage devices can store electrical energy during off-peak hours and provide power to relevant users or electrical equipment during peak hours.

[0095] In some embodiments, the energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0096] In some embodiments, during the charging process of the battery device from 0% state of charge (SOC) to 100% SOC, the ambient temperature of the external environment in which the battery device is located is room temperature, for example, 25°C.

[0097] In some embodiments, during the charging process of the battery device or any of the battery cells 7 constituting the battery device from 10% SOC to 80% SOC, the ambient temperature of the external environment in which the battery device is located is room temperature, for example, 25°C.

[0098] For example, the charging process of the battery device or any of the battery cells 7 constituting the battery device from 10% SOC to 80% SOC can be performed as follows:

[0099] Charge from 10% SOC to 25% SOC at a constant current of 7.0C;

[0100] Charge from 25% SOC to 30% SOC at a constant current of 7.0C;

[0101] Charge from 30% SOC to 35% SOC at a constant current of 7.0C;

[0102] Charge from 35% SOC to 40% SOC at a constant current of 7.0C;

[0103] Charge from 40% SOC to 45% SOC at a constant current of 6.7C;

[0104] Charge from 45% SOC to 50% SOC at a constant current of 6.5C;

[0105] Charge from 50% SOC to 55% SOC at a constant current of 6.0C;

[0106] Charge from 55% SOC to 60% SOC at a constant current of 5.8C;

[0107] Charge from 60% SOC to 65% SOC at a constant current of 5.5C;

[0108] Charge from 65% SOC to 70% SOC at a constant current of 5.2C;

[0109] Charge from 70% SOC to 75% SOC at a constant current of 5.0C;

[0110] Charge from 75% SOC to 80% SOC at a constant current of 4.8C.

[0111] In some embodiments, the charging time for the battery device or any of the battery cells 7 constituting the battery device from 10% state of charge to 80% state of charge is 5 min to 20 min, optionally less than or equal to 12 min, and further optionally 5 min to 8 min. The ambient temperature of the battery device at 10% state of charge is room temperature, for example, 25°C. Exemplarily, the charging time for the battery device from 10% state of charge to 80% state of charge is 20 min, 19 min, 18 min, 17 min, 16 min, 15 min, 14.5 min, 14 min, 13.5 min, 13 min, 12.5 min, 12 min, 11.5 min, 11 min, 10.5 min, 10 min, 9.5 min, 9 min, 8.5 min, 8 min, 7.5 min, 7 min, 6.5 min, 6 min, 5 min, or any range of two of the above values.

[0112] Figure 3 is a structural schematic diagram of a battery cell provided in some embodiments of this application; Figure 4 is a cross-sectional schematic diagram of a battery cell provided in some embodiments of this application; Figure 5 is a schematic diagram of the electrode assembly of a battery cell provided in some embodiments of this application; Figure 6 is a cross-sectional schematic diagram of Figure 5 along the K1-K1 direction; Figure 7 is a schematic diagram of the electrode sheet of a battery cell provided in some embodiments of this application; Figure 8 is a cross-sectional schematic diagram of Figure 7 along the K2-K2 direction; Figure 9 is another schematic diagram of the electrode sheet shown in Figure 7, wherein the active material layer is omitted.

[0113] Referring to Figures 3 to 9, an embodiment of this application provides a battery cell 7, which includes a housing 20 and an electrode assembly 10, with at least a portion of the electrode assembly 10 housed within the housing 20.

[0114] In some embodiments,

[0115] The outer shell 20 may be a hollow structure, with an internal cavity for accommodating the electrode assembly 10 and the electrolyte.

[0116] The outer casing 20 can be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc. In some embodiments, the outer casing 20 can be a sealed structure or a non-sealed structure. As an example, when the outer casing 20 is a non-sealed structure, it serves to protect the electrode assembly 10, and a sealing bag is included between the outer casing 20 and the electrode assembly 10. The sealing bag is used to encapsulate the electrode assembly 10 and the electrolyte. Specifically, the sealing bag can be a bag-shaped insulating component or an aluminum-plastic film. When the outer casing 20 is a sealed structure, it is used to encapsulate the electrode assembly 10 and electrolyte components.

[0117] In some embodiments, the casing 20 of the battery cell 7 is a cylindrical casing, a square casing, a prismatic casing, or a casing of other shapes.

[0118] In some embodiments, the housing 20 includes a housing 21 and an end cap 22, the housing 21 having an opening, and the end cap 22 being connected to the housing 21 and covering the opening.

[0119] The housing 21 is a component used to fit the end cap 22 to form the internal cavity of the battery cell 7. The formed internal cavity can be used to accommodate the electrode assembly 10, the electrolyte, and other components.

[0120] The housing 21 and the end cap 22 can be separate components. For example, an opening can be provided on the housing 21, and the end cap 22 can be used to close the opening to form an internal cavity for the battery cell 7.

[0121] The housing 21 can be of various shapes and sizes, such as cuboid or cylindrical. Specifically, the shape of the housing 21 can be determined according to the specific shape and size of the electrode assembly 10. The housing 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0122] The shape of the end cap 22 can be adapted to the shape of the housing 21 to fit the housing 21. The material of the end cap 22 can be the same as or different from the material of the housing 21. Optionally, the end cap 22 can be made of a material with a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.), so that the end cap 22 is not easily deformed when subjected to compression and impact, so that the battery cell 7 can have higher structural strength and improve reliability.

[0123] The end cap 22 is connected to the housing 21 by welding, bonding, snap-fitting or other means.

[0124] The housing 21 may be open at one end or open at both ends. In some examples, the housing 21 may be a structure with an opening on one side, and one end cap 22 is provided to cover the housing 21. In other examples, the housing 21 may also be a structure with openings on both sides, and two end caps 22 are provided, with the two end caps 22 respectively covering the two openings of the housing 21.

[0125] The shape of the housing 21 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is a cylindrical structure, then a cylindrical housing can be selected; if the electrode assembly 10 is a cuboid structure, then a cuboid housing can be selected. Optionally, both the electrode assembly 10 and the housing 21 are cuboid structures.

[0126] In some embodiments, housing 21 includes sidewall 212 surrounding electrode assembly 10.

[0127] In some embodiments, the sidewall 212 includes two first shell walls 212a, a second shell wall 212b, and a third shell wall 212c. The two first shell walls 212a are opposite to each other along the thickness direction Z1 of the battery cell 7, the second shell walls 212b and the third shell wall 212c are opposite to each other, and the second shell walls 212b and the third shell wall 212c are connected through the first shell walls 212a.

[0128] For example, housing 21 is a square housing.

[0129] In some embodiments, the second shell wall 212b includes a first sub-wall 212d and a second sub-wall 212e continuously disposed along the thickness direction Z1, and the first sub-wall 212d and the second sub-wall 212e are welded together. The first sub-wall 212d and the second sub-wall 212e can be welded using methods such as panel welding or laser welding, with panel welding being a preferred option. Since the area of ​​the second shell wall 212b is relatively small and its expansion is relatively small, the weld seam is located on the second shell wall 212b, which can reduce the risk of leakage from the battery cell 7.

[0130] For example, the housing 21 can be assembled by welding, which can reduce the molding difficulty of the housing 21 and help to increase the size of the housing 21.

[0131] In some embodiments, in the battery device, the second shell wall 212b and the third shell wall 212c can be arranged vertically, and the second shell wall 212b can be disposed on the upper side of the electrode assembly 10. Because the second shell wall 212b has a weld seam with the weld seam facing upwards, the risk of leakage from the battery cell 7 is reduced.

[0132] In some embodiments, the size of the battery cell 7 along the thickness direction Z1 is 10mm to 30mm, for example 10mm, 12mm, 14mm, 15mm, 16mm, 18mm, 20mm, 22mm, 24mm, 25mm, 26mm, 28mm, 30mm or any range of two of the above values.

[0133] The dimension of the battery cell 7 along the thickness direction Z1 can characterize the thickness of the battery cell 7. In other words, the thickness of the battery cell 7 is between 10 mm and 30 mm. When the thickness of the battery cell 7 is within the above range, the thickness of the battery cell 7 is relatively small, which is conducive to rapid heat dissipation inside the battery cell 7 and reduces the risk of thermal runaway.

[0134] In some embodiments, the wall thickness of the housing 21 is 0.1 mm to 0.5 mm, for example, 0.1 mm, 0.12 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, 0.21 mm, 0.22 mm, 0.23 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0. The thickness of the housing 21 may be 3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, 0.4mm, 0.41mm, 0.42mm, 0.43mm, 0.44mm, 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.5mm, or any combination of two of the above values. Optionally, the wall thickness of the housing 21 may be from 0.3mm to 0.4mm.

[0135] When the wall thickness of the housing 21 is within the above range, the housing 21 is relatively thin, which is conducive to the rapid heat dissipation of the housing 21.

[0136] In some embodiments, the thickness of the first shell wall 212a is 0.1 mm to 0.5 mm.

[0137] In some embodiments, the thickness of the second shell wall 212b is 0.1 mm to 0.5 mm.

[0138] In some embodiments, the thickness of the third shell wall 212c is 0.1 mm to 0.5 mm.

[0139] Electrode assembly 10 is a component in the battery cell 7 where electrochemical reactions occur. The housing 21 may contain one or more electrode assemblies 10.

[0140] In some embodiments, the electrode assembly 10 includes a first electrode 11 and a second electrode 12, one of which is a positive electrode 13 and the other is a negative electrode 14.

[0141] The electrode assembly 10 can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0142] In some examples, the electrode assembly 10 is a wound structure. The first electrode 11 and the second electrode 12 are wound along the winding direction of the electrode assembly 10.

[0143] In other examples, electrode assembly 10 is a stacked structure.

[0144] As an example, multiple first electrode plates 11 and multiple second electrode plates 12 can be set, and multiple first electrode plates 11 and multiple second electrode plates 12 can be stacked alternately.

[0145] As an example, multiple first electrode plates 11 can be provided, and second electrode plates 12 can be folded to form multiple stacked folded segments, with a first electrode plate 11 sandwiched between adjacent folded segments.

[0146] As an example, both the first electrode 11 and the second electrode 12 are folded to form multiple stacked folded segments.

[0147] In some embodiments, both the first electrode 11 and the second electrode 12 include an electrode body 15 and at least one tab 16. At least a portion of the electrode body 15 is provided with an active material layer 151, and at least a portion of the tab 16 is not provided with an active material layer 151.

[0148] At least a portion of the electrode body 15 is provided with an active material layer 151, which can be understood as all areas of the electrode body 15 being provided with an active material layer 151; or, a portion of the electrode body 15 is provided with an active material layer 151, while another portion may not be provided with an active material layer 151.

[0149] At least a portion of the tab 16 is not provided with an active material layer 151, which can be understood as the entire area of ​​the tab 16 not being provided with an active material layer 151; or a portion of the tab 16 is not provided with an active material layer 151, while another portion of the tab 16 is provided with an active material layer 151, for example, a portion of the tab 16 near the electrode body 15 is provided with an active material layer 151.

[0150] To more clearly illustrate this application, the tab 16 of the first electrode 11 is defined as the first tab 16a, and the electrode body 15 of the first electrode 11 is defined as the first electrode body 15a. The tab 16 of the second electrode 12 is defined as the second tab 16b, and the electrode body 15 of the second electrode 12 is defined as the second electrode body 15b.

[0151] There can be one or more first electrode ears 16a. In some examples, there can be multiple first electrode ears 16a. Multiple first electrode ears 16a can be disposed on the same side of the first electrode body 15a, or they can be disposed on opposite sides of the first electrode body 15a.

[0152] There can be one or more second pole ears 16b. In some examples, there can be multiple second pole ears 16b, which can be located on the same side of the second pole body 15b or on opposite sides of the second pole body 15b.

[0153] In some embodiments, the active material layer 151 of the positive electrode 13 may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials of batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM)622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Modified compounds refer to substances obtained by modification methods such as doping or coating based on the above-mentioned substances.

[0154] The active material layer 151 of the negative electrode sheet 14 may employ a negative electrode active material known in the art for use in battery cells 7. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials in battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0155] In some embodiments, the electrode body 15 includes a current collector 152, at least a portion of the active material layer 151 is disposed on the current collector 152, and an electrode tab 16 is connected to the current collector 152. The current collector 152 has two surfaces opposite each other in its own thickness direction, and the active material layer 151 is disposed on either or both of the two opposite surfaces of the current collector 152.

[0156] For example, the current collection section 152 of the first electrode body 15a is defined as the first current collection section 152a, and the current collection section 152 of the second electrode body 15b is defined as the second current collection section 152b.

[0157] In some embodiments, the current collector 152 and the tab 16 are integrally formed.

[0158] In some embodiments, the current collector 152 of the positive electrode 13 can be defined as the positive current collector 152c. The positive current collector 152c can be made of metal foil, conductive polymer material, carbon material, or composite current collector. For example, as a metal foil, pure metal, alloy, or surface-treated metal can be used, including but not limited to stainless steel, copper, aluminum, nickel, nickel alloy, titanium, or silver. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0159] In some embodiments, the current collector 152 of the negative electrode 14 can be defined as the negative current collector 152d. The negative current collector 152d can be made of metal foil, conductive polymer material, carbon material, or composite current collector. For example, as a metal foil, pure metal, alloy, or surface-treated metal can be used, including but not limited to stainless steel, copper, aluminum, nickel, nickel alloy, titanium, or silver. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0160] In some embodiments, the material of the current collector 152 of the positive electrode 13 and the material of the tab 16 of the positive electrode 13 can both be aluminum. The material of the current collector 152 of the negative electrode 14 and the material of the tab 16 of the negative electrode 14 can both be copper.

[0161] In some embodiments, the electrode assembly 10 includes a separator 17 that separates the first electrode 11 and the second electrode 12.

[0162] At least a portion of the separator 17 is located between the first electrode 11 and the second electrode 12. During the charging and discharging process of the battery cell 7, active ions (e.g., lithium ions) are inserted and extracted back and forth between the first electrode 11 and the second electrode 12. The separator 17, located between the first electrode 11 and the second electrode 12, serves to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0163] In some embodiments, the separator 17 includes a separator membrane. The separator membrane in this application can be any known porous membrane with good chemical and mechanical stability.

[0164] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different.

[0165] Inorganic particle coating, organic particle coating, or organic / inorganic composite coating can also be applied to the surface of the separator.

[0166] The separator 17 can be a separate component located between the first electrode 11 and the second electrode 12, or it can be attached to the surface of the first electrode 11 or the surface of the second electrode 12.

[0167] In some embodiments, the separator 17 is a solid electrolyte. The solid electrolyte is disposed between the first electrode 11 and the second electrode 12, and serves to both transport ions and isolate the positive and negative electrodes.

[0168] In some embodiments, the battery cell 7 further includes an electrode terminal 30 disposed on the housing 20, the electrode terminal 30 being electrically connected to the tab portion 16.

[0169] The tab 16 can be directly connected to the electrode terminal 30, or it can be indirectly connected to the electrode terminal 30 through other conductive structures.

[0170] The electrode terminal 30 can be used to realize the electrical connection between the electrode assembly 10 and the external circuit, so as to realize the charging or discharging of the battery cell 7.

[0171] In some embodiments, there are multiple electrode terminals 30, a portion of which is electrically connected to a first electrode tab 16a, and another portion of which is electrically connected to a second electrode tab 16b. The electrode terminal 30 that is electrically connected to and has the same electrical charge as the first electrode tab 16a is the first electrode terminal 30a, and the electrode terminal 30 that is electrically connected to and has the same electrical charge as the second electrode tab 16b is the second electrode terminal 30b.

[0172] In some examples, the first electrode 11 is the positive electrode 13, the second electrode 12 is the negative electrode 14, the first electrode terminal 30a is the positive terminal, and the second electrode terminal 30b is the negative terminal; in other examples, the first electrode 11 is the negative electrode 14, the second electrode 12 is the positive electrode 13, the first electrode terminal 30a is the negative terminal, and the second electrode terminal 30b is the positive terminal.

[0173] The first electrode terminal 30a can be one or more. The second electrode terminal 30b can also be one or more. For example, the first electrode terminal 30a can be two, three, or four, and the second electrode terminal 30b can be two, three, or four, etc.

[0174] The first electrode terminal 30a and the second electrode terminal 30b can be disposed on the housing 21 or on the end cover 22. Optionally, the first electrode terminal 30a and the second electrode terminal 30b are disposed on the end cover 22.

[0175] In some examples, the housing 20 is provided with an end cap 22. Optionally, the first electrode terminal 30a and the second electrode terminal 30b may be disposed on the same end cap 22.

[0176] In other examples, there are two end caps 22, which are arranged opposite to each other. Optionally, each end cap 22 is provided with a first electrode terminal 30a and a second electrode terminal 30b. Alternatively, one end cap 22 is provided with the first electrode terminal 30a, and the other end cap 22 is provided with the second electrode terminal 30b.

[0177] In some embodiments, the volumetric energy density of the battery cell 7 is between 350 Wh / L and 450 Wh / L. Exemplarily, the volumetric energy density of the battery cell 7 is 350 Wh / L, 375 Wh / L, 380 Wh / L, 390 Wh / L, 400 Wh / L, 410 Wh / L, 420 Wh / L, 430 Wh / L, 450 Wh / L, or a range of any two of the above values. The volumetric energy density of the battery cell 7 is relatively high.

[0178] In this embodiment, the volumetric energy density of the battery cell 7 has a meaning known in the art and can be detected using equipment and methods known in the art. For example, the description will be based on an upper limit charging voltage of 3.65V and a battery discharge cutoff voltage of 2.0V.

[0179] Place the battery cell at 25°C and charge it to 3.65V with a constant current of 0.33C, then charge it to 0.05C with a constant voltage, and discharge it to 2.0V with a constant current of 0.33C. Record the discharge capacity A0 at this point, in Ah. Use calipers to measure the length, width, and height of the battery cell (generally calculated based on the battery casing dimensions, excluding the height of the electrode terminals and the insulating film outside the casing). Calculate the volume of the battery cell V0, in L. The volumetric energy density of the battery cell VED = (A0 × discharge plateau voltage) / V0, in Wh / L.

[0180] Referring to Figures 3 to 9, this application embodiment provides a battery cell 7, which includes a housing 20, an electrode assembly 10, and electrode terminals 30. At least a portion of the electrode assembly 10 is housed within the housing 20, and the electrode terminals 30 are disposed on the housing 20. The electrode assembly 10 includes a first electrode 11 and a second electrode 12, one of which is a positive electrode 13, and the other is a negative electrode 14. Both the first electrode 11 and the second electrode 12 include an electrode body 15 and at least one tab 16. At least a portion of the electrode body 15 is provided with an active material layer 151, and at least a portion of the tab 16 is not provided with an active material layer 151. The electrode body 15 and the tab 16 are arranged along a first direction X, and the dimension of the tab 16 along a second direction Y is less than or equal to the dimension of the electrode body 15 along the second direction Y. The first direction X, the second direction Y, and the thickness direction T of the electrode body 15 are perpendicular to each other. The tab 16 is electrically connected to the electrode terminals 30.

[0181] The first electrode 11 satisfies: a 2 +b 2 The maximum value is 6000 to 110000; where a represents the distance along the first direction X between any point A of the electrode body 15 in the first electrode 11 and the electrode tab 16 closest to point A among all electrode tabs 16, and the unit of a is mm; b represents the distance along the second direction Y between point A of the first electrode 11 and the electrode tab 16 closest to point A among all electrode tabs 16, and the unit of b is mm.

[0182] Each electrode (first electrode 11 or second electrode 12) may have one or more tabs 16. In some examples, there may be multiple tabs 16. Multiple tabs 16 may be located on the same side of the electrode body 15 along the first direction X, or they may be located on opposite sides of the electrode body 15 along the first direction X.

[0183] In some examples, the electrode assembly 10 may be a stacked structure, the electrode body 15 may be a rectangular structure, and one of the first direction X and the second direction Y may be parallel to the length direction of the electrode body 15, while the other may be parallel to the width direction of the electrode body 15.

[0184] In other examples, the electrode assembly 10 may be a wound structure, the second direction Y may be the winding direction of the electrode assembly 10, and the first direction X may be parallel to the winding axis of the electrode assembly 10. Optionally, the dimension of the electrode body 15 along the first direction X may be the length of the electrode body 15 in the unfolded state, and the dimension of the electrode body 15 along the second direction Y may be the width of the electrode body 15 in the unfolded state; or, the dimension of the electrode body 15 along the first direction X may be the width of the electrode body 15 in the unfolded state, and the dimension of the electrode body 15 along the second direction Y may be the width of the electrode body 15 in the unfolded state.

[0185] The dimension of the electrode body 15 along the first direction X can be greater than, equal to or less than the dimension of the electrode body 15 along the second direction Y.

[0186] For example, a 2 +b 2 The maximum value is 6000, 10000, 15000, 20000, 25000, 30000, 35000, 40000, 45000, 50000, 55000, 60000, 65000, 70000, 75000, 80000, 85000, 90000, 95000, 100000, 105000, 110000, or a range of any two of the above values.

[0187] Within the same first electrode 11, there are multiple points A, a 2 +b 2 a has multiple values; 2 +b 2 The maximum value can basically characterize the longest electron transport distance in this electrode, by analyzing a 2 +b 2 The design maximizes the value of electrons and shortens the electron transport path.

[0188] Any point within the electrode body 15 can be defined as point A, and point A can be arbitrarily chosen within the electrode body 15. Any point can be a point with an area, for example, a point with an area of ​​0.01 μm. 2 The area of ​​the dot is much smaller than the area of ​​the tab 16, and the size of the dot has virtually no interference with the measurement of the spacing. The thickness of the electrode body 15 is small, and its thickness has a negligible impact on the measurement of the spacing.

[0189] In this embodiment of the application, a 2 +b 2 Setting the maximum value to greater than or equal to 6000 allows the electrode body 15 to have a larger area, which is beneficial for increasing the capacity and energy density of the battery cell 7. Setting a 2 +b 2 Setting the maximum value to less than or equal to 110000 can reduce the maximum electron transport path in the electrode, making the electron transport path relatively short, thereby reducing the internal resistance of the battery cell 7, reducing the heat generated by the battery cell 7 during charging, and improving the cycle performance and fast charging performance of the battery cell 7.

[0190] In some embodiments, the size of the tab 16 along the second direction Y is smaller than the size of the electrode body 15 along the second direction Y.

[0191] In some embodiments, the electrode assembly 10 may be a stacked electrode assembly. Exemplarily, the electrode assembly 10 includes a plurality of first electrodes 11 and a plurality of second electrodes 12, which are alternately stacked. The stacking direction of the first electrodes 11 and the second electrodes 12 may be perpendicular to a first direction X and a second direction Y.

[0192] Compared to wound electrode assemblies, stacked electrode assemblies make better use of the internal space of the housing 20; using stacked electrode assemblies can improve the energy density of the battery cell 7. Stacked electrode assemblies have good heat dissipation performance, and their internal structure supports a more uniform heat distribution, which helps improve heat generation and extend the cycle life of the battery cell 7. Battery cells 7 using stacked electrode assemblies have better rate performance, which helps achieve high-current discharge.

[0193] The first electrode 11, the second electrode 12, and the separator 17 are stacked together to form an electrode assembly 10.

[0194] In some embodiments, the electrode assembly 10 may be a wound electrode assembly. Exemplarily, the electrode assembly 10 includes a first electrode 11 and a second electrode 12, the first electrode 11 and the second electrode 12 being wound along a winding direction.

[0195] In some embodiments, the active material layer 151 of the positive electrode 13 includes a lithium phosphate with an olivine structure. Using a lithium phosphate with an olivine structure is beneficial for improving the reliability of the battery cell 7, extending the service life of the battery cell 7, and improving the high-temperature performance of the battery cell 7. This application embodiment will use a... 2 +b 2 Setting the maximum value to 6000 to 110000 can make the electron transport path in the electrode relatively short, reduce the influence of lithium phosphate with olivine structure on internal resistance, and improve the fast charging performance of battery cell 7.

[0196] In some embodiments, the battery cell 7 is a square battery cell.

[0197] In some embodiments, the electrode body 15 has a size of 320mm to 650mm along the length direction Z2 of the battery cell 7, and the first direction X is parallel to the length direction Z2 or the width direction Z3 of the battery cell 7. The embodiments of this application can, to a certain extent, balance the energy density and fast charging performance of the battery cell 7.

[0198] As an example, in the length direction Z2 of the battery cell 7, the size of the electrode body 15 is 320mm, 350mm, 400mm, 450mm, 500mm, 550mm, 600mm, 650mm or any combination of the above two values.

[0199] In this embodiment, the electrode body 15 is set to a size greater than or equal to 320 mm, which increases the capacity of a single battery cell 7, thus reducing the number of battery cells 7 in the battery device and improving the energy density of the battery device. In this embodiment, the electrode body 15 is set to a size less than or equal to 650 mm, which makes the electron transport path along the length direction Z2 of the battery cell 7 relatively short, thereby reducing the internal resistance of the battery cell 7, reducing heat generation during charging, and improving the cycle performance and fast charging performance of the battery cell 7.

[0200] In some embodiments, the first electrode 11 includes one or more first electrode tabs 16a; optionally, there are multiple first electrode tabs 16a, and the multiple first electrode tabs 16a are disposed on at least one side of the first electrode body 15a along the first direction X.

[0201] The first electrode tab 16a includes a first end 161 and a second end 162 that are opposite to each other along the first direction X. The first end 161 is disposed close to the first electrode body 15a, and the second end 162 is disposed away from the first electrode body 15a. The distance between point A and the first electrode tab 16a along the first direction X refers to the distance between point A and the first end 161 along the first direction X. In Figure 7, 'a' represents the distance between point A (point A1 or point A2) and the first electrode tab 16a along the first direction X.

[0202] The first electrode ear 16a may be configured as one or more. When there are multiple first electrode ears 16a, the first electrode ear 16a that is closest to point A along the second direction Y refers to the first electrode ear 16a that has the smallest distance from point A along the second direction Y.

[0203] In the first electrode 11, the first electrode tab 16a closest to point A is defined as the closest electrode tab. The closest electrode tab includes a first edge and a second edge that are opposite to each other along the second direction Y. In the second direction Y, the first edge is disposed close to point A, and the second edge is disposed away from point A. The distance between point A and the first electrode tab 16a closest to point A along the second direction Y refers to the distance between point A and the first edge along the second direction Y.

[0204] In the projection plane perpendicular to the first direction X, the orthographic projection of the part closest to the tab overlaps with the orthographic projection of the first electrode body 15a; in the projection plane perpendicular to the first direction X, the orthographic projection of the part closest to the tab lies within the orthographic projection of the first electrode body 15a. Point A is any point in the first electrode body 15a. Ignoring the thickness of the first electrode body 15a, when the projection of point A along the first direction X lies within the projection of the part closest to the tab along the first direction X, the distance between point A and the part closest to the tab along the second direction Y can be considered to be 0. When the projection of point A along the first direction X lies outside the projection of the part closest to the tab along the first direction X, the distance between point A and the part closest to the tab along the second direction Y can be considered to be greater than 0. This distance is the distance between point A and the first edge along the second direction Y.

[0205] In some embodiments, for electrons located at the same position, there may be multiple transmission paths between them and the tab 16. The distance that the electron travels along the shortest path is taken as the electron transmission distance at that point.

[0206] For electrons at different positions within the same electrode (i.e., electrons at different points A), the electron transport distance at each position is calculated, and the longest electron transport distance is selected as the maximum electron transport distance. This maximum value is represented by a. 2 +b 2 The maximum value is represented by a. 2 +b 2 The design maximizes the electron transport path, reduces internal resistance, and improves the fast charging performance of the battery cell 7.

[0207] In some embodiments, the dimension L4 of the electrode body 15 along the first direction X is smaller than the dimension W2 of the electrode body 15 along the second direction Y.

[0208] For example, the size of the first electrode body 15a along the first direction X is smaller than the size of the first electrode body 15a along the second direction Y.

[0209] For example, the dimension of the second electrode body 15b along the first direction X is smaller than the dimension of the second electrode body 15b along the second direction Y.

[0210] In some examples, the electrode assembly 10 has a stacked structure, with the first direction X, the width direction of the electrode body 15, and the width direction Z3 of the battery cell 7 all parallel, and the second direction Y, the length direction of the electrode body 15, and the length direction Z2 of the battery cell 7 all parallel.

[0211] In some examples, the electrode assembly 10 has a wound structure, with a first direction X parallel to the winding axis of the electrode assembly 10 and a second direction Y parallel to the winding direction of the electrode assembly 10.

[0212] In some embodiments, the first electrode 11 has multiple tabs 16, and all the tabs 16 of the first electrode 11 are disposed on the same side of the electrode body 15 along the first direction X.

[0213] By setting multiple tabs 16, the current-carrying area can be increased, the electron transport path of the electrode body 15 can be shortened, thereby reducing the internal resistance of the battery cell 7. By setting all the tabs 16 of the first electrode 11 on the same side of the electrode body 15 along the first direction X, the total space occupied by the tabs 16 in the first direction X can be reduced, providing more space for the electrode body 15, improving space utilization, and increasing the energy density of the battery cell 7.

[0214] In some embodiments, the second electrode 12 has multiple tabs 16, and all the tabs 16 of the second electrode 12 are disposed on the same side of the electrode body 15 along the first direction X.

[0215] For example, all the first electrode tabs 16a and all the second electrode tabs 16b can be disposed on the same side of the electrode assembly 10 along the first direction X, or they can be disposed on both sides of the electrode assembly 10 along the first direction X.

[0216] In some embodiments, the dimension L4 of the electrode body 15 along the first direction X is 50mm-200mm. As an example, L4 is 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm, 120mm, 130mm, 140mm, 150mm or any range of two of the above values.

[0217] In this embodiment, L4 is set to be greater than or equal to 50mm to increase the capacity and energy density of the battery cell 7. Setting L4 to be less than or equal to 200mm can reduce the maximum value of a, thereby reducing the internal resistance of the battery cell 7, reducing the heat generated by the battery cell 7 during charging, and improving the cycle performance and fast charging performance of the battery cell 7.

[0218] In some embodiments, the electrode body 15 has a dimension of 80mm-150mm along the first direction X.

[0219] In some embodiments, the dimension W2 of the electrode body 15 along the second direction Y is 320mm to 650mm, such as 320mm, 350mm, 400mm, 450mm, 500mm, 550mm, 600mm, 650mm or any range of two of the above values.

[0220] In some embodiments, the first electrode 11 satisfies: a 2 +b 2The maximum value is between 6400 and 45000. Optionally, a 2 +b 2 The maximum value is 6400 to 25000. The embodiments of this application can further balance the energy density and fast charging performance of the battery cell 7.

[0221] Optionally, all the tabs 16 of the first electrode 11 are located on the same side of the electrode body 15 along the first direction X.

[0222] In some embodiments, as shown in Figure 7, for an electron located at the same point A2, there may be multiple transmission paths such as C1 and C2 (only two paths, C1 and C2, are shown in the figure, and it is not excluded that the electron may also be transmitted in other ways); when the distance of C1 is greater than the distance of C2, the transmission distance of the electron located at point A2 is defined as the distance of C2; when C1 and C2 are equal, the transmission distance of the electron located at point A2 can be defined as either the distance of C1 or the distance of C2.

[0223] Specifically, for point A2, since the first electrode tab 16a is located on the same side of the first electrode body 15a, a is equal to the dimension L4 of the first electrode body 15a along the first direction X; L4 can be equal to the distance between point A2 and the electrode tab 16 closest to point A2 along the first direction X.

[0224] b1 represents the distance between point A2 and an adjacent first electrode tab 16a along the second direction Y, and b2 represents the distance between point A2 and another adjacent first electrode tab 16a along the second direction Y. If b1 is greater than b2, then b2 represents the distance between point A2 and the electrode tab 16 closest to point A2 among all electrode tabs 16 along the second direction Y. In this case, the transmission distance of the electron located at point A2 is defined as the C2 distance.

[0225] If b1 equals b2, then either b1 or b2 can represent the distance between point A2 and the pole 16 closest to point A2 along the second direction Y. In this case, the electron transmission distance at point A2 can be defined as the distance C1 or the distance C2.

[0226] For the same first electrode 11, there are multiple points A, such as A1 and A2.

[0227] The electron located at point A1, i.e., the electron located on the edge of the first electrode body 15a, has a dimension L4 equal to that of the first electrode body 15a along the first direction X. b3 represents the distance between point A1 and the adjacent first electrode tab along the second direction Y. C3 represents the electron transport distance at point A1.

[0228] Taking the electron transport distance of the electron located at point A2 as C2 as an example, if C2 is greater than or equal to C3, then C2 is the longest electron transport distance in the first pole piece 11, a2 +b 2 The maximum value is the square of C2; if C2 is less than C3, then C3 is the longest electron transport distance in the first electrode 11, a 2 +b 2 The maximum value is the square of C3.

[0229] In some embodiments, the sum of the dimensions of all the tabs 16 located on the same side of the electrode body 15 along the second direction Y is W1, and the dimension of the electrode body 15 along the second direction Y is W2. The first electrode 11 satisfies that W1 / W2 is 0.5 to 1.0.

[0230] As an example, the average dimension of the tab 16 along the second direction Y is W11, where W1 can be the sum of W11 of all tabs 16. Exemplarily, the dimension of the tab 16 along the second direction Y can be measured at multiple locations, thereby calculating the average dimension of the tab 16 along the second direction Y.

[0231] The tab 16 can be a rectangular structure or an irregular structure. For example, if the tab 16 is rectangular, the dimension of the tab 16 at any position along the second direction Y can be W11; if the tab 16 is an irregular structure, the electrode body 15 points in the direction of the tab 16, and the dimension of the tab 16 along the second direction Y gradually increases.

[0232] There can be one or more electrode tabs 16 located on the same side of the electrode body 15.

[0233] In some examples, there are multiple tabs 16 located on the same side of the electrode body 15, and the size W11 of the multiple tabs 16 can be the same or different.

[0234] After measuring the average size W11 of each tab 16 separately, sum all the average sizes W11 to obtain W1.

[0235] For example, if the size W11 of the multiple tabs 16 is n, and the number of tabs 16 located on the same side of the electrode body 15 is n, then W1 = n × W11.

[0236] For example, W1 / W2 is 0.5, 0.55, 0.6, 2 / 3, 0.7, 0.75, 0.8, 0.85, 0.9, 1.0 or a range of any two of the above values.

[0237] In this embodiment, W1 / W2 is set to 0.5 to 1.0, which makes the connection area between the tab 16 and the electrode body 15 relatively large, and also makes the current-passing area of ​​the tab 16 relatively large, which is beneficial to reduce DC resistance, reduce heat generation, and improve the fast charging performance of the battery cell 7.

[0238] In some embodiments, the first tab 16a and the first electrode body 15a are connected, and the first tab 16a includes a first end 161 connected to the first electrode body 15a. Setting W1 / W2 to 0.5 to 1.0 means that the cross-section of the first end 161 along the thickness direction of the first tab 16a is relatively large, the contact surface between the first tab 16a and the first electrode body 15a is relatively large, and the current carrying capacity of the first tab 16a is strong, which can improve the power performance and cycle performance of the battery cell 7.

[0239] Optionally, the current collector 152 of the first electrode tab 16a and the first electrode body 15a is an integral structure, which makes the internal resistance of the first electrode 11 lower and can further improve the power performance and cycle performance of the battery cell 7.

[0240] In some embodiments, W1 / W2 is set to 0.5 to 0.9. Alternatively, W1 / W2 is set to 0.6 to 0.8.

[0241] In some embodiments, the first electrode 11 has multiple tabs 16 disposed on the same side of the electrode body 15, which is beneficial for the uniform distribution of electrons in the first electrode 11 and for improving fast charging performance.

[0242] In some embodiments, the distance D1 between two adjacent tabs 16 along the second direction Y is greater than 0 and less than or equal to 300 mm.

[0243] Optionally, D1 can be 100mm, 120mm, 140mm, 150mm, 160mm, 180mm, 200mm, 220mm, 240mm, 250mm, 260mm, 280mm, 300mm, or a range of any two of the above values.

[0244] In this embodiment, D1 is set to be greater than 0 to reduce the influence between adjacent tabs 16 during bending, thus reducing the difficulty of bending the tabs 16. Setting D1 to less than or equal to 300mm helps to reduce the maximum value of b, thereby making the electron transport path relatively short, which reduces the internal resistance of the battery cell 7, reduces the heat generated by the battery cell 7 during charging, and helps to improve the cycle performance and fast charging performance of the battery cell 7.

[0245] In some embodiments, the electrode body 15 includes a current collector 152, and at least a portion of the active material layer 151 is disposed on the surface of the current collector 152. The current collector 152 includes a first current collector region 1521 and a second current collector region 1522 arranged along a second direction Y, and an electrode tab 16 extends from the end of the second current collector region 1522 along a first direction X. The dimension of the first current collector region 1521 along the second direction Y is L1, and the dimension of the second current collector region 1522 along the second direction Y is L2. 2≤L1 / L2≤30.

[0246] For example, in FIG9, the junction of the first current collection area 1521 and the second current collection area 1522, as well as the junction of the second current collection area 1522 and the tab 16, are shown by dashed lines.

[0247] In some examples, a tab 16 is led out from one end of the second current collector 1522; in other examples, tabs 16 are led out from both ends of the second current collector 1522.

[0248] As an example, L1 / L2 can be 2, 3, 5, 6, 8, 10, 12, 15, 18, 20, 22, 25, 28 or 30.

[0249] As an example, in a projection plane perpendicular to the first direction X, the orthographic projection of the tab 16 is located within the orthographic projection of the second collector region 1522, and the orthographic projection of the tab 16 does not overlap with the entire first collector region 1521.

[0250] Compared to the first collector 1521, the second collector 1522 is closer to the tab 16; the longest transmission path of the first collector 1521 is longer than the longest transmission path of the second collector 1522. In this embodiment, L1 / L2 is set to be greater than or equal to 2 to increase the area of ​​the first current collector 1521 or decrease the area of ​​the second current collector 1522. Increasing the area of ​​the first current collector 1521 can increase the capacity of the electrode body 15, while decreasing the area of ​​the second current collector 1522 can reduce the size of the tab 16 along the second direction Y, thereby reducing the space occupied by the tab 16 and the difficulty of bending the tab 16. In this embodiment, L1 / L2 is set to be less than or equal to 30 to limit the extent to which the area of ​​the first current collector 1521 increases or the area of ​​the second current collector 1522 decreases. Limiting the extent to which the area of ​​the first current collector 1521 increases can reduce the maximum value of b, shortening the longest transmission path of the first current collector 1521. Limiting the extent to which the area of ​​the second current collector 1522 decreases can ensure that the overcurrent area of ​​the tab 16 meets the requirements of fast charging.

[0251] In some embodiments, 6 ≤ L1 / L2 ≤ 20.

[0252] In some embodiments, the electrode body 15 includes a current collector 152, and at least a portion of the active material layer 151 is disposed on the surface of the current collector 152. The current collector 152 includes a first current collector region 1521 and a second current collector region 1522 arranged along a second direction Y, and an electrode tab 16 extends from the end of the second current collector region 1522 along a first direction X. The dimension of the first current collector region 1521 along the second direction Y is L1, and the dimension of the first current collector region 1521 along the first direction X is L3. 0.1≤L3 / L1≤5.

[0253] As an example, L3 / L1 can be 0.1, 0.2, 0.3, 0.5, 0.7, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8 or 5.

[0254] In this embodiment, L3 / L1 is set to 0.1-5, which reduces a while given a fixed area of ​​the first current collection region 1521. 2 +b 2 The maximum value of , thus making the electron transport path relatively short, thereby reducing the internal resistance of the battery cell 7.

[0255] In some embodiments, 0.5 ≤ L3 / L1 ≤ 2 can further reduce a. 2 +b 2 The maximum value of this makes the electron transport path relatively short, thereby reducing the internal resistance of the battery cell 7.

[0256] In some embodiments, the current collection section 152 includes a plurality of first current collection areas 1521 and a plurality of second current collection areas 1522, which are alternately arranged along a second direction Y. Each second current collection area 1522 is connected to at least one tab 16.

[0257] By setting multiple first current collectors 1521 and multiple second current collectors 1522, the electron transmission path can be relatively short, which can effectively reduce the internal resistance of the battery cell 7, and each tab 16 carries a smaller current and the current distribution is more uniform, which is conducive to the rapid charging of the battery cell 7.

[0258] The L1 values ​​of multiple first collectors 1521 can be equal or unequal. The L2 values ​​of multiple second collectors 1522 can be equal or unequal.

[0259] As shown in Figures 7 and 9, in some embodiments, for point A1, given a fixed area of ​​the first collector region 1521, the distance C3 is shortest when a and b3 are equal. That is, for the first collector region 1521 where point A1 is located, the distance C3 is shortest when L3 / L1 equals 1.

[0260] In some embodiments, for point A2, given a fixed area of ​​the first collector region 1521, the distance C1 is the shortest when a = b1 = b2. That is, for the first collector region 1521 where point A2 is located, the distance C3 is the shortest when L3 / L1 equals 0.5.

[0261] In some embodiments, the electrode assembly 10 includes a tab group 18, which includes at least two stacked tab portions 16.

[0262] For example, the electrode assembly 10 includes a plurality of tab groups 18, the plurality of tab groups 18 including a first tab group 18a and a second tab group 18b, the first tab group 18a including a first tab portion 16a stacked on both sides, and the second tab group 18b including at least two second tab portions 16b stacked on both sides.

[0263] The first electrode group 18a can be one or more. The second electrode group 18b can be one or more.

[0264] In some embodiments, the electrode assembly 10 includes a plurality of tab groups 18 with the same polarity, each tab group 18 including at least two stacked tab portions 16. Exemplarily, there are multiple first tab groups 18a, and / or multiple second tab groups 18b.

[0265] In some embodiments, the electrode assembly 10 has a stacked structure. There are multiple first electrode plates 11 and second electrode plates 12. The first electrode plate 11 may include one or more first electrode tabs 16a.

[0266] In some examples, the first electrode 11 includes a first electrode tab 16a, and the number of first electrode tabs 16a is the same as the number of first electrode 11s. All the first electrode tabs 16a are divided into multiple first electrode tab groups 18a.

[0267] In other examples, the first electrode 11 includes a plurality of first electrode tabs 16a. For example, each first electrode 11 includes m first electrode tabs 16a, and there are m first electrode tab groups 18a, with the m first electrode tabs 16a of the first electrode 11 belonging to different first electrode tab groups 18a.

[0268] In other embodiments, the electrode assembly 10 has a wound structure. The first electrode 11 includes a plurality of first electrode tabs 16a, and the first electrode tabs 16a of the first electrode 11 are divided into a plurality of first electrode tab groups 18a.

[0269] In some embodiments, a plurality of first tab groups 18a may be disposed on the same side of the electrode assembly 10 along the first direction X, or may be disposed on both sides of the electrode assembly 10 along the first direction X. A plurality of second tab groups 18b may be disposed on the same side of the electrode assembly 10 along the first direction X, or may be disposed on both sides of the electrode assembly 10 along the first direction X.

[0270] In some examples, multiple first tab groups 18a and multiple second tab groups 18b are disposed on the same side of the electrode assembly 10; in other examples, multiple first tab groups 18a are disposed on one side of the electrode assembly 10 along the first direction X, and multiple second tab groups 18b are disposed on the other side of the electrode assembly 10 along the first direction X. In still other examples, the electrode assembly 10 has at least one first tab group 18a and at least one second tab group 18b on each side along the first direction X.

[0271] In some embodiments, the battery cell 7 includes an adapter 40 that connects the electrode terminal 30 and the tab assembly 18.

[0272] For example, the adapter 40 can be a sheet-like structure, or of course, other structural forms.

[0273] In some embodiments, the adapter 40 may include a conductive polymer or a conductive metal material, and the conductive metal material may include copper, aluminum, or an alloy containing the aforementioned metal elements.

[0274] In some embodiments, the battery cell 7 includes a plurality of adapters 40, the plurality of adapters 40 including a first adapter 40a and a second adapter 40b. The first adapter 40a is connected to a first tab group 18a and a first electrode terminal 30a to electrically connect the first tab group 18a and the first electrode terminal 30a. The second adapter 40b is connected to a second tab group 18b and a second electrode terminal 30b to electrically connect the second tab group 18b and the second electrode terminal 30b.

[0275] There may be one or more first adapters 40a. There may be one or more first electrode terminals 30a.

[0276] In some examples, there is one first adapter 40a, which is connected to all the first tab groups 18a. Alternatively, there are one or more first electrode terminals 30a, for example, multiple first electrode terminals 30a, and the first adapter 40a can be connected to multiple first electrode terminals 30a simultaneously.

[0277] In other examples, there are multiple first adapters 40a, each of which is connected to at least one first electrode group 18a; optionally, the number of first adapters 40a is the same as the number of first electrode groups 18a, and multiple first adapters 40a and multiple first electrode groups 18a are configured in a one-to-one correspondence. There are one or more first electrode terminals 30a; for example, there is one first electrode terminal 30a, and multiple first adapters 40a are connected to the same first electrode terminal 30a; for example, the number of first adapters 40a is the same as the number of first electrode terminals 30a, and multiple first adapters 40a and multiple first electrode terminals 30a are configured in a one-to-one correspondence.

[0278] There may be one or more first adapters 40a. There may be one or more first electrode terminals 30a.

[0279] In some examples, there is one second adapter 40b, which is connected to all the second electrode groups 18b. Alternatively, there are one or more second electrode terminals 30b, for example, multiple second electrode terminals 30b, and the second adapter 40b can be connected to multiple second electrode terminals 30b simultaneously.

[0280] In other examples, there are multiple second adapters 40b, each of which is connected to at least one second tab group 18b; optionally, the number of second adapters 40b is the same as the number of second tab groups 18b, and multiple second adapters 40b and multiple second tab groups 18b are arranged in a one-to-one correspondence. There are one or more second electrode terminals 30b; for example, there is one second electrode terminal 30b, and multiple second adapters 40b are connected to the same second electrode terminal 30b; for example, the number of second adapters 40b is the same as the number of second electrode terminals 30b, and multiple second adapters 40b and multiple second electrode terminals 30b are arranged in a one-to-one correspondence.

[0281] In some embodiments, the electrode assembly 10 includes a plurality of tab groups 18 of the same polarity, each tab group 18 including at least two stacked tab portions 16. The battery cell 7 includes an adapter 40 connected to the electrode terminal 30, the adapter 40 being connected to the plurality of tab groups 18. The same adapter 40 can connect multiple tab groups 18 of the same polarity to the electrode terminal 30, which facilitates current collection and output and simplifies the structure of the battery cell 7.

[0282] In some embodiments, the adapter 40 includes a first adapter portion 41 and a second adapter portion 42 connected to each other. The second adapter portion 42 is connected to the electrode terminal 30, and the first adapter portion 41 is connected to the tab assembly 18.

[0283] There can be one or more second adapters 42. One second adapter 42 can be connected to one electrode terminal 30 or to multiple electrode terminals 30 simultaneously. For example, each second adapter 42 is connected to a corresponding electrode terminal 30.

[0284] There can be one or more first adapters 41. One first adapter 41 can be connected to one electrode group 18 or to multiple electrode groups 18 at the same time.

[0285] In some embodiments, a plurality of tab assemblies 18 are disposed on the same side of the electrode assembly 10 along a first direction X. The adapter 40 includes a second adapter portion 42 and a first adapter portion 41 connected to each other, the second adapter portion 42 being connected to the electrode terminal 30, and the first adapter portion 41 being connected to the plurality of tab assemblies 18.

[0286] Placing the tabs 18 of the same polarity on the same side of the electrode assembly 10 helps reduce the difficulty of connecting the first adapter 41 to multiple tabs 18 and simplifies the structure of the battery cell 7.

[0287] In some embodiments, the second adapter 42 is bent relative to the first adapter 41.

[0288] In some embodiments, the adapter 40 includes two second adapter portions 42, which are respectively connected to the two ends of the first adapter portion 41. The battery cell 7 includes a plurality of electrode terminals 30, and the two second adapter portions 42 are respectively connected to two electrode terminals 30.

[0289] For example, multiple tab groups 18 of the same polarity are arranged along the second direction Y, and two second adapters 42 are respectively connected to the two ends of the first adapter 41 along the second direction Y.

[0290] For example, two second adapter portions 42 are respectively disposed on both sides of the electrode assembly 10 along the second direction Y.

[0291] In some embodiments, the battery cell 7 further includes a conductive element 50, which is connected to the tab assembly 18 and the adapter 40.

[0292] In some examples, at least a portion of the conductive element 50 is disposed between the tab assembly 18 and the adapter 40. In other examples, at least a portion of the tab assembly 18 is disposed between the conductive element 50 and the adapter 40.

[0293] The conductive element 50 can increase the current carrying capacity between the tab assembly 18 and the adapter 40, which is beneficial to improving fast charging performance and reducing heat generation.

[0294] In some embodiments, the conductive element 50, the tab assembly 18, and the adapter 40 are welded together to form a welded portion.

[0295] In some embodiments, there are multiple conductive elements 50, and each conductive element 50 is connected to a corresponding tab group 18. In other embodiments, one conductive element 50 is connected to multiple tab groups 18 of the same polarity.

[0296] In some embodiments, the conductive member 50 includes a first conductive portion 51 and a second conductive portion 52. The first conductive portion 51 extends along a second direction Y and is connected to the tab assembly 18 and the first adapter portion 41. The second conductive portion 52 is connected to the first conductive portion 51 and protrudes from the first conductive portion 51 along a first direction X. The second conductive portion 52 is connected to the second adapter portion 42.

[0297] In some embodiments, the conductive element 50 has conductivity and may include a conductive polymer or a conductive metal material, which may include copper, aluminum, or an alloy containing the aforementioned metal elements.

[0298] In some embodiments, the thickness of the conductive element 50 is from 0.5 mm to 2.0 mm, for example, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, or any combination of two of the above values. When the thickness of the conductive element 50 is within the above range, the current carrying capacity can be effectively improved, and the fast charging capability can be enhanced.

[0299] In some embodiments, the battery cell 7 includes a plurality of conductive elements 50, the plurality of conductive elements 50 including a first conductive element 50a and a second conductive element 50b, the first conductive element 50a being connected to a first tab group 18a and a first adapter 40a, and the second conductive element 50b being connected to a second tab group 18b and a second adapter 40b.

[0300] In some embodiments, there are multiple first conductive elements 50a, and the first conductive elements 50a and the first tab group 18a are connected in a one-to-one correspondence. The multiple first conductive elements 50a are connected to the first adapter 40a. This connection method is beneficial to improving the weight energy density of the battery cell 7.

[0301] In some embodiments, there are multiple first tab groups 18a located on the same side of the electrode assembly 10, and the first conductive element 50a can be a continuous sheet structure that connects multiple first tab groups 18a.

[0302] In some embodiments, all first tab groups 18a are disposed on one side of the electrode assembly 10 along the first direction X, and all second tab groups 18b are disposed on the other side of the electrode assembly 10 along the first direction X.

[0303] In some embodiments, the first adapter 40a includes two second adapter portions 42 and one first adapter portion 41, and the second adapter 40b includes two second adapter portions 42 and one first adapter portion 41. The first adapter 40a and the second adapter 40b are arranged along a first direction X. The first adapter portion 41 of the first adapter 40a is connected to all the first electrode tabs, and the two second adapter portions 42 of the first adapter 40a are respectively connected to two first electrode terminals 30a. The first adapter portion 41 of the second adapter 40b is connected to all the second electrode tabs, and the two second adapter portions 42 of the second adapter 40b are respectively connected to two second electrode terminals 30b.

[0304] In some embodiments, the second direction Y is parallel to the length direction Z2 of the battery cell 7. At least one first electrode terminal 30a is disposed on at least one side of the electrode assembly 10 along the length direction Z2 of the battery cell 7.

[0305] For example, all first electrode terminals 30a are disposed on one side of the electrode assembly 10 along the length direction Z2 of the battery cell 7.

[0306] For example, multiple first electrode terminals 30a are respectively disposed on both sides of the electrode assembly 10 along the length direction Z2 of the battery cell 7. This arrangement can shorten the electron migration path and is beneficial to improving fast charging performance.

[0307] For example, there are two first electrode terminals 30a, one of which is disposed on one side of the electrode assembly 10 and the other is disposed on the other side of the electrode assembly 10. Alternatively, for example, there are four first electrode terminals 30a, two of which are disposed on one side of the electrode assembly 10 and the other two are disposed on both sides of the electrode assembly 10.

[0308] For example, when the first electrode terminal 30a is disposed on at least one side of the electrode assembly 10 along the length direction Z2 of the battery cell 7, and the first electrode tab 16a is disposed on at least one side of the first electrode body 15a along the width direction Z3 of the battery cell 7, the first adapter 40a is more conducive to the connection between the first electrode tab 16a and the first electrode terminal 30a.

[0309] In some embodiments, the first adapter portion 41 extends along the length direction Z2 of the battery cell 7, the first adapter portion 41 is connected to the first electrode tab portion 16a, the second adapter portion 42 is connected to the first adapter portion 41 and protrudes from the first adapter portion 41 along the width direction Z3 of the battery cell 7, and is connected to the first electrode terminal 30a.

[0310] In some embodiments, where the first electrode tab 16a and the first electrode terminal 30a are located on the same side of the first electrode body, the first adapter 40a may consist only of the first adapter portion 41.

[0311] In some embodiments, the first electrode group 18a and the first electrode terminal 30a are respectively disposed on different sides of the first electrode body.

[0312] In some embodiments, the electrode terminal 30 may be a one-piece molded structure. Alternatively, multiple components may be fixedly connected by welding, riveting, or other means to form the electrode terminal 30.

[0313] Figure 10 is a schematic diagram of the first electrode of a battery cell provided in some other embodiments of this application.

[0314] Referring to FIG10, in some embodiments, the dimension L4 of the electrode body 15 along the first direction X is smaller than the dimension W2 of the electrode body 15 along the second direction Y.

[0315] In some embodiments, a plurality of first electrode ears 16a are respectively disposed on both sides of the first electrode body 15a along the first direction X.

[0316] In some embodiments, a 2 +b 2 The maximum value is 6400 to 45000, and the selectable value is 6400 to 25000.

[0317] In some embodiments, the first electrode body 15a is provided with at least two first electrode ears 16a on each side along the first direction X.

[0318] In some embodiments, referring to FIG10, for an electron located at the same point A2, there may be multiple transmission paths such as C1, C2, C3 and C4. When the C2 distance is the smallest, the transmission distance of the electron located at point A2 is defined as the C2 distance.

[0319] Specifically, since the first electrode tab 16a is disposed on both sides of the first electrode body 15a, a is equal to half of the dimension L4 of the first electrode body 15a along the first direction X, that is, 1 / 2 × L1 is equal to the distance between point A2 and the electrode tab 16 closest to point A2 among all electrode tabs 16 along the first direction X.

[0320] b1 represents the distance between point A2 and an adjacent first electrode ear 16a along the second direction Y, and b2 represents the distance between point A2 and another adjacent first electrode ear 16a along the second direction Y. For example, distance C1 is equal to distance C4, and distance C2 is equal to distance C3.

[0321] If b1 is greater than b2, then b2 represents the distance between point A2 and the pole 16 closest to point A2 along the second direction Y. In this case, the transmission distance of the electron located at point A2 is defined as the C2 distance.

[0322] If b1 equals b2, then either b1 or b2 can represent the distance between point A2 and the pole 16 closest to point A2 along the second direction Y. In this case, the electron transmission distance at point A can be defined as the C1 distance or the C2 distance.

[0323] For the same first electrode 11, there are multiple positions, such as A1 and A2.

[0324] The electron located at point A1, i.e., the electron located on the edge of the first pole piece 15a, has a value of 1 / 2 × L1. b3 represents the distance between point A1 and the adjacent first pole piece 16a along the second direction Y. C5 represents the electron transport distance at point A1.

[0325] Taking the electron transport distance of an electron located at point A2 as C2 as an example, if C2 is greater than or equal to C5, then C2 is the longest electron transport distance in the first pole piece 11, a 2 +b 2 The maximum value is the square of C2; if C2 is less than C5, then C5 is the longest electron transport distance in the first electrode 11, a 2 +b 2 The maximum value is the square of C5.

[0326] Whether all the first tabs 16a are located on the same side of the first electrode body 15a along the first direction X, or all the first tabs 16a are located on opposite sides of the first electrode body 15a along the first direction X, it is beneficial for the uniform distribution of electrons in the first electrode 11 and for improving fast charging performance.

[0327] In some embodiments, the first electrode ear portion 16a located on the same side of the first electrode body 15a may be multiple, such as two, three, four, five, six, etc.; four may be selected.

[0328] Figure 11 is a schematic diagram of the first electrode provided in some other embodiments of this application.

[0329] Referring to Figure 11, in some embodiments, W1 = W2. The embodiments of this application can maximize the flow area of ​​the tab 16, which is beneficial for increasing the flow area and reducing a. 2 +b 2 The maximum value of the battery cell 7 is reduced, the internal resistance of the battery cell 7 is reduced, the heat generated by the battery cell 7 during the charging process is reduced, which is beneficial to improving the cycle performance and fast charging performance of the battery cell 7.

[0330] In some embodiments, there is one first electrode tab 16a. Exemplarily, the dimension of the first electrode tab 16a along the second direction Y may be equal to the dimension of the first electrode body 15a along the second direction Y. The first electrode 11 may have a full electrode tab structure.

[0331] For any point A on the first electrode body 15a, the value of b is 0.

[0332] Figure 12 is a schematic diagram of the first electrode provided in some other embodiments of this application.

[0333] Referring to FIG12, in some embodiments, there are multiple first electrode tabs 16a, and the multiple first electrode tabs 16a are located on the same side of the first electrode body 15a along the first direction X.

[0334] Optionally, the first pole ear 16a has a dimension of 50mm-200mm along the second direction Y, and can be selected as 50mm, 75mm, 100mm, 125mm, 150mm, 175mm or 200mm.

[0335] In some embodiments, the first electrode 11 is provided with two first electrode ears 16a.

[0336] Figure 13 is a schematic diagram of the first electrode provided in some other embodiments of this application.

[0337] Referring to FIG13, in some embodiments, the dimension L4 of the electrode body 15 along the first direction X is greater than the dimension W2 of the electrode body 15 along the second direction Y.

[0338] For example, the size of the first electrode body 15a along the first direction X is larger than the size of the first electrode body 15a along the second direction Y.

[0339] For example, the dimension of the second electrode body 15b along the first direction X is greater than the dimension of the second electrode body 15b along the second direction Y.

[0340] In some examples, the electrode assembly 10 has a stacked structure, with the second direction Y, the width direction of the electrode body 15, and the width direction Z3 of the battery cell 7 all parallel, and the first direction X, the length direction of the electrode body 15, and the length direction Z2 of the battery cell 7 all parallel.

[0341] In some examples, the electrode assembly 10 has a wound structure, with a first direction X parallel to the winding axis of the electrode assembly 10 and a second direction Y parallel to the winding direction of the electrode assembly 10.

[0342] In some embodiments, the first electrode 11 includes one or more first electrode tabs 16a. Exemplarily, there are multiple first electrode tabs 16a, which may be disposed on one side of the first electrode body 15a along the first direction X, or may be disposed on both sides of the first electrode body 15a along the first direction X.

[0343] In some embodiments, the dimension L4 of the electrode body 15 along the first direction X is 320 mm to 650 mm.

[0344] In this embodiment, setting L4 to greater than or equal to 320 mm increases the capacity of a single battery cell 7, which helps reduce the number of battery cells 7 in the battery device and improves the energy density of the battery device. In this embodiment, setting L4 to less than or equal to 650 mm shortens the electron transport path of the electrode in the first direction X, thereby reducing the internal resistance of the battery cell 7, reducing heat generation during charging, and improving the cycle performance and fast charging performance of the battery cell 7.

[0345] Setting L4 to less than or equal to 650mm will make a less than or equal to 650.

[0346] In some embodiments, the first electrode 11 satisfies: a 2 +b 2 The maximum value is between 25,600 and 110,000. Optionally, a 2 +b 2 The maximum value is between 25,600 and 90,000. The embodiments of this application can further balance the energy density and fast-charging performance of the battery cell 7.

[0347] In some embodiments, a plurality of first electrode tabs 16a of the first electrode 11 are disposed on the same side of the first electrode body 15a along the first direction X.

[0348] Referring to Figure 14, for an electron located at the same point A2, there may be multiple transmission paths such as C1 and C2 (only two paths, C1 and C2, are shown in the figure, and it is not excluded that the electron may also be transmitted in other ways). When the distance of C1 is greater than the distance of C2, the transmission distance of the electron located at point A2 is defined as the distance of C2; when C1 and C2 are equal, the transmission distance of the electron located at point A2 can be defined as either the distance of C1 or the distance of C2.

[0349] Specifically, for point A2, since the first electrode tab 16a is located on the same side of the first electrode body 15a, a is equal to the dimension L4 of the first electrode body 15a along the first direction X; L4 can be equal to the distance between point A2 and the electrode tab 16 closest to point A2 along the first direction X.

[0350] b1 represents the distance between point A2 and an adjacent first electrode tab 16a along the second direction Y, and b2 represents the distance between point A2 and another adjacent first electrode tab 16a along the second direction Y. If b1 is greater than b2, then b2 represents the distance between point A2 and the electrode tab 16 closest to point A2 among all electrode tabs 16 along the second direction Y. In this case, the transmission distance of the electron located at point A2 is defined as the C2 distance.

[0351] If b1 equals b2, then either b1 or b2 can represent the distance between point A2 and the pole 16 closest to point A2 along the second direction Y. In this case, the electron transmission distance at point A2 can be defined as the distance C1 or the distance C2.

[0352] For the same first electrode 11, there are multiple points A, such as A1 and A2.

[0353] The electron located at point A1, i.e., the electron located on the edge of the first electrode body 15a, has a dimension L4 equal to that of the first electrode body 15a along the first direction X. b3 represents the distance between point A1 and the adjacent first electrode tab along the second direction Y. C3 represents the electron transport distance at point A1.

[0354] Taking the electron transport distance of the electron located at point A2 as C2 as an example, if C2 is greater than or equal to C3, then C2 is the longest electron transport distance in the first pole piece 11, a 2 +b 2 The maximum value is the square of C2; if C2 is less than C3, then C3 is the longest electron transport distance in the first electrode 11, a 2 +b 2 The maximum value is the square of C3.

[0355] In some embodiments, the distance D1 between two adjacent tabs 16 along the second direction Y is greater than 0 and less than or equal to 300 mm.

[0356] Optionally, D1 can be 100mm, 120mm, 140mm, 150mm, 160mm, 180mm, 200mm, 220mm, 240mm, 250mm, 260mm, 280mm, 300mm, or a range of any two of the above values.

[0357] Figure 14 is a schematic diagram of the first electrode provided in some other embodiments of this application.

[0358] Referring to FIG14, in some embodiments, the first electrode 11 has multiple electrode tabs 16, and the multiple electrode tabs 16 are respectively disposed on both sides of the electrode body 15 along the first direction X.

[0359] Compared to the size of the electrode body 15 along the second direction Y, the size of the electrode body 15 along the first direction X is larger; by distributing multiple tabs 16 on both sides of the electrode body 15 along the first direction X, the maximum value of a can be reduced, thereby shortening the transmission path of electrons in the first electrode 11, which is beneficial to improving fast charging performance.

[0360] In some embodiments, a 2 +b 2 The maximum value is 25600 to 110000, and the selectable value is 25600 to 90000.

[0361] Referring to Figure 14, for an electron located at the same point A, there may be multiple transmission paths such as C1 and C2. When the C2 distance is the smallest, the transmission distance of the electron located at point A is defined as the C2 distance.

[0362] Specifically, since the first electrode tab 16a is disposed on both sides of the first electrode body 15a, a is equal to half of the dimension L4 of the first electrode body 15a along the first direction X, that is, 1 / 2 × L1 is equal to the distance between point A and the electrode tab 16 closest to point A among all electrode tabs 16 along the first direction X.

[0363] There is one first electrode tab 16a located on the same side. b represents the distance between point A and the electrode tab 16 closest to point A among all electrode tabs 16 along the second direction Y. In this case, distances C1 and C2 are the same and can both be used as the longest electron transmission distance in the first electrode 11. 2 +b 2 The maximum value is the square of C1.

[0364] Whether all the first tabs 16a are located on the same side of the first electrode body 15a along the first direction X, or all the first tabs 16a are located on opposite sides of the first electrode body 15a along the first direction X, it is beneficial for the uniform distribution of electrons in the first electrode 11 and for improving fast charging performance.

[0365] In some embodiments, the first electrode ear portion 16a located on the same side of the first electrode body 15a may be multiple, such as two, three, four, five, six, etc.; four may be selected.

[0366] In some embodiments, FIG15 is a schematic diagram of a second electrode provided in some embodiments of this application.

[0367] Referring to Figure 15, in some embodiments, the second electrode 12 satisfies: e 2 +f 2The maximum value is between 6000 and 110000. e represents the distance along the first direction X between any point B of the electrode body 15 in the second electrode 12 and the electrode tab 16 closest to point B among all electrode tabs 16; the unit of e is mm. f represents the distance along the second direction Y between point B of the second electrode 12 and the electrode tab 16 closest to point B among all electrode tabs 16; the unit of f is mm.

[0368] When the second electrode 12 of this embodiment satisfies the above conditions, the electron transmission path is relatively short, which can effectively reduce the internal resistance of the battery cell 7 and make the current distribution more uniform, thereby facilitating the rapid charging of the battery cell 7.

[0369] In this embodiment, the number and arrangement of the second electrode ears 16b are the same as those of the first electrode ears 16a, and will not be described again here. The structure of the second electrode 12 is the same as that of the first electrode 11, and will not be described again here.

[0370] Figure 16 is a cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application.

[0371] Referring to FIG16, in some embodiments, the first direction X is parallel to the width direction Z3 of the battery cell 7.

[0372] In some embodiments, at least one first electrode terminal 30a is disposed on at least one side of the electrode assembly 10 along the width direction Z3 of the battery cell 7, which can shorten the electron migration path and improve fast charging performance.

[0373] In some examples, all first electrode terminals 30a are disposed on one side of the electrode assembly 10 along the width direction Z3 of the battery cell 7. Alternatively, multiple first electrode terminals 30a are disposed on both sides of the electrode assembly 10 along the width direction Z3 of the battery cell 7.

[0374] In some embodiments, at least one second electrode terminal 30b is disposed on at least one side of the electrode assembly 10 along the width direction Z3 of the battery cell 7. This arrangement can shorten the electron migration path and improve fast charging performance.

[0375] For example, all second electrode terminals 30b are disposed on one side of the electrode assembly 10 along the width direction Z3 of the battery cell 7. The first electrode terminal 30a and the second electrode terminal 30b can be disposed on both sides of the electrode assembly 10 along the width direction Z3 of the battery cell 7, respectively, and electrically connected to the first tab 16a and the second tab 16b. This embodiment of the application can reduce the risk of short circuit between the first electrode terminal 30a and the second electrode terminal 30b.

[0376] For example, there are two first electrode terminals 30a and two second electrode terminals 30b. The two first electrode terminals 30a are disposed on one side of the electrode assembly 10 along the width direction Z3 of the battery cell 7, and the two second electrode terminals 30b are disposed on the other side of the electrode assembly 10 along the width direction Z3 of the battery cell 7.

[0377] For example, multiple second electrode terminals 30b are respectively disposed on both sides of the electrode assembly 10 along the width direction Z3 of the battery cell 7. This arrangement can further shorten the electron migration path and improve fast charging performance. In this case, the electrode assembly 10 has a first electrode terminal 30a and a second electrode terminal 30b on one side along the width direction Z3 of the battery cell 7, and the electrode assembly 10 has a first electrode terminal 30a and a second electrode terminal 30b on the other side along the width direction Z3 of the battery cell 7.

[0378] In some embodiments, at least one second electrode terminal 30b is disposed on at least one side of the electrode assembly 10 along the length direction Z2 of the battery cell 7.

[0379] For example, multiple second electrode terminals 30b are respectively disposed on both sides of the electrode assembly 10 along the length direction Z2 of the battery cell 7. This arrangement can shorten the electron migration path and improve fast charging performance. In this case, the electrode assembly 10 has a first electrode terminal 30a and a second electrode terminal 30b on one side along the length direction Z2 of the battery cell 7, and the electrode assembly 10 has a first electrode terminal 30a and a second electrode terminal 30b on the other side along the length direction Z2 of the battery cell 7.

[0380] For example, there are two second electrode terminals 30b, one of which is disposed on one side of the electrode assembly 10 along the length direction Z2 of the battery cell 7, and the other is disposed on the other side of the electrode assembly 10 along the length direction Z2 of the battery cell 7. There are two first electrode terminals 30a, one of which is disposed on one side of the electrode assembly 10, and the other is disposed on the other side of the electrode assembly 10.

[0381] For example, all the second electrode terminals 30b are disposed on one side of the electrode assembly 10 along the length direction Z2 of the battery cell 7. In this case, the first electrode terminal 30a and the second electrode terminal 30b can be disposed on both sides of the electrode assembly 10 along the length direction Z2 of the battery cell 7, and electrically connected to the first tab 16a and the second tab 16b, respectively.

[0382] Figure 17 is a cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application.

[0383] Referring to FIG17, in some embodiments, a plurality of tabs 18 are respectively disposed on both sides of the electrode assembly 10 along the first direction X. The adapter 40 includes a second adapter portion 42 and two first adapter portions 41. The second adapter portion 42 is connected to the electrode terminal 30, and the two first adapter portions 41 are respectively connected to the two ends of the second adapter portion 42 along the first direction X. Each first adapter portion 41 is connected to at least one tab 18.

[0384] In some examples, multiple first tab groups 18a are respectively disposed on both sides of the electrode assembly 10 along the first direction X, and multiple second tab groups 18b are respectively disposed on both sides of the electrode assembly 10 along the first direction X. On the same side of the electrode assembly 10 along the first direction X, first tab portions 16a and second tab portions 16b are disposed along the second direction Y.

[0385] The second adapter portion 42 of the first adapter 40a and the second adapter portion 42 of the second adapter 40b are respectively disposed on both sides of the electrode assembly 10 along the second direction Y.

[0386] In some embodiments, there is one first electrode terminal 30a and one second electrode terminal 30b.

[0387] Figure 18 is a cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application.

[0388] Referring to Figure 18, in some embodiments, there is one first electrode terminal 30a and one second electrode terminal 30b. The first electrode terminal 30a and the second electrode terminal 30b are located on both sides of the electrode assembly 10 along the length direction Z2 of the battery cell 7, and the first electrode terminal 30a and the second electrode terminal 30b are staggered along the width direction Z3 of the battery cell 7. Specifically, when all the second tabs 16b are located on the same side of the second electrode body 15b along the width direction Z3 of the battery cell 7, and all the first tabs 16a are located on the same side of the first electrode body 15a along the width direction Z3 of the battery cell 7, the first tabs 16a and the second tabs 16b are located on both sides of the electrode body 15 along the width direction Z3 of the battery cell 7, with the first electrode terminal 30a located close to the first tab 16a and the second electrode terminal 30b located close to the second tab 16b. This arrangement results in a shorter electron transmission distance, which is more conducive to improving the fast charging capability of the battery cell 7.

[0389] Figure 19 is a schematic diagram of the first electrode provided in some other embodiments of this application; Figure 20 is a cross-sectional view of Figure 19 along the K3-K3 direction.

[0390] Referring to Figures 19 and 20, in some embodiments, the electrode body 15 of the first electrode 11 includes a coating area 153 and a transition area 154 arranged along a first direction X. An active material layer 151 is disposed in the coating area 153, while neither the transition area 154 nor the tab 16 has an active material layer 151. The transition area 154 connects the coating area 153 and the tab 16. The first electrode 11 also includes an insulating member 19, at least a portion of which is disposed in the transition area 154.

[0391] Exemplarily, the coating area 153 includes the active material layer 151 and the portion of the current collector 152 covered by the active material layer 151, and the transition area 154 includes the portion of the current collector 152 not covered by the active material layer 151. Exemplarily, the transition area 154 may be covered by the insulating member 19.

[0392] By providing the insulating element 19, the risk of burrs on the electrode body 15 of the second electrode 12 becoming conductive with the first electrode 11 can be reduced.

[0393] In some embodiments, the insulating element 19 may include at least one of an insulating coating, an insulating tape, or an insulating colloid.

[0394] In some embodiments, the first electrode 11 may be a positive electrode 13.

[0395] To more clearly illustrate this application, the electrode body 15 of the positive electrode 13 is defined as the positive electrode body 15c, the tab 16 of the positive electrode 13 is defined as the positive electrode tab 16c, the active material layer 151 of the positive electrode 13 is defined as the positive active material layer 151a containing positive active material, and the current collector 152 of the positive electrode 13 is defined as the positive current collector 152c.

[0396] The positive electrode 13 includes a positive current collector 152c and a positive active material layer 151a disposed on at least one surface of the positive current collector 152c and comprising a positive active material. For example, the positive current collector 152c has two surfaces opposite to each other in its thickness direction, and the positive active material layer 151a is disposed on either or both of the two opposite surfaces of the positive current collector 152c.

[0397] The upper limit voltage for charging and the lower limit voltage for discharging of battery cell 7 vary depending on the positive electrode active material. For example, when the phosphate material includes lithium iron phosphate, the upper limit voltage for charging can be 3.65V and the lower limit voltage for discharging can be 2.0V, or the upper limit voltage for charging can be 3.8V and the lower limit voltage for discharging can be 2.0V. Another example is when the phosphate material includes lithium manganese iron phosphate, the upper limit voltage for charging can be 4.3V and the lower limit voltage for discharging can be 2.0V.

[0398] The following uses a charging upper limit voltage of 3.65V and a discharging cutoff voltage of 2.0V as an example to illustrate the state of a single battery cell: In this embodiment, the 100% state of charge (SOC) and 0% state of charge (SOC) of a single battery cell are defined as follows.

[0399] The battery cell is charged at a constant current charging rate of 0.33C to the upper limit of the charging voltage, and then charged at a constant voltage to 0.05C, which corresponds to the 100% SOC state of the battery cell. The battery cell is then discharged at a constant current discharging rate of 0.33C to the cutoff voltage, which corresponds to the 0% SOC state of the battery cell.

[0400] In some embodiments, the compaction density of the positive electrode active material layer of the battery cell at 0% state of charge (SOC) is 2.30 g / cm³. 3 Up to 2.70 g / cm 3 ; 2.40 g / cm³ is optional 3 Up to 2.55 g / cm 3 For example, at 0% state of charge (SOC), the compaction density of the positive electrode active material layer in a single battery cell is 2.30 g / cm³. 3 2.32 g / cm 3 2.35g / cm 3 2.38g / cm 3 2.40 g / cm 3 2.42 g / cm 3 2.45g / cm 3 2.48 g / cm 3 2.50g / cm 3 2.52g / cm 3 2.55g / cm 3 2.56 g / cm 3 2.57g / cm 3 2.58g / cm 3 2.60g / cm 3 2.62 g / cm 3 2.65g / cm 3 2.68g / cm 3 2.70 g / cm 3 Or a range consisting of any two of the above values.

[0401] When the compaction density of the positive electrode active material layer is within the above range, it is beneficial to improve the energy density of the battery cell. Furthermore, since the positive electrode active material layer is densely packed, the contact resistance between particles is small, which can further reduce the resistance of the electrode sheet, thereby reducing heat generation under fast charging, alleviating the problem of aggravated negative electrode side reactions caused by heat accumulation, and improving the cycle performance of the battery cell.

[0402] In some embodiments, the single-sided coating weight of the positive electrode active material layer is 250 mg / 1540.25 mm. 2 Up to 330mg / 1540.25mm 2 The option is 275mg / 1540.25mm. 2 Up to 300mg / 1540.25mm 2 For example, the single-sided coating weight of the positive electrode active material layer is 250 mg / 1540.25 mm. 2 260mg / 1540.25mm 2 270mg / 1540.25mm 2 280mg / 1540.25mm 2 290mg / 1540.25mm 2 300mg / 1540.25mm 2 310mg / 1540.25mm 2 320mg / 1540.25mm 2 330mg / 1540.25mm 2 Or a range consisting of any two of the above values.

[0403] When the single-sided coating weight of the positive electrode active material layer is within the above range, the heat generation per unit area of ​​the positive electrode sheet will not be too large, which alleviates the problem of aggravated side reactions on the negative electrode due to heat accumulation, improves the cycle performance of the battery cell, and can increase the energy density of the battery cell.

[0404] In this embodiment, the compaction density of the positive electrode active material layer of a battery cell at 0% state of charge (SOC) is a term known in the art. This means that the positive electrode sheet is disassembled from the battery cell at 0% SOC, and the compaction density of the positive electrode active material layer is measured. For example, a single-sided coated positive electrode sheet (if double-sided coated, the positive electrode active material layer on one side can be wiped off first) is cut into small circular pieces with an area of ​​S1, weighed, and recorded as M1, and its thickness H1 is measured. Then, the positive electrode active material layer of the weighed positive electrode sheet is wiped off, the weight of the positive current collector is weighed and recorded as M0, and its thickness H0 is measured. The single-sided coating weight of the positive electrode active material layer = (weight of the positive electrode sheet M1 - weight of the positive electrode current collector M0) / S1, the thickness of the positive electrode active material layer = the thickness of the positive electrode sheet H1 - the thickness of the positive electrode current collector H0, and the compaction density of the positive electrode active material layer = the single-sided coating weight of the positive electrode active material layer / the thickness of the positive electrode active material layer.

[0405] In some embodiments, the positive electrode active material comprises a lithium phosphate with an olivine structure. In other embodiments, the positive electrode active material may also comprise lithium-containing transition metal oxides, examples of which include, but are not limited to, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds.

[0406] In this embodiment, the lithium phosphate with olivine structure can be phosphate particles or a material obtained by coating and modifying them. For example, the lithium phosphate with olivine structure includes phosphate particles and a coating layer. The coating layer is coated on the surface of the phosphate particles. For example, the coating layer includes elements such as carbon, which improves the conductivity of the phosphate particles, reduces the powder resistivity of the material, and is beneficial to the migration rate of lithium ions, thereby improving the fast charging capability of the battery and reducing the heat generation of the battery cell.

[0407] In some embodiments, phosphate particles include those with the general formula Li x1 A y1 Me a M b P 1-c X c Y z The compound contains the following components: 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, and 0.9 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a ≤ 1.5, 0 ≤ b ≤ 0.5, and 0.9 ≤ a + b ≤ 1.5, 0 ≤ c ≤ 0.5, 3 ≤ z ≤ 5; A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of Cl, C, and N; and Y includes one or more of O and F. Phosphate particles exhibit excellent cycle stability, which is beneficial for improving the cycle performance of battery cells.

[0408] For example, the phosphate particles include one or more of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4. During the charging and discharging process, active ions such as Li are de-intercalated and consumed in a single battery cell, resulting in different molar contents of Li in different discharged states. In the examples of positive electrode active materials such as LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4, the molar contents of Li represent the initial state of the material, i.e., the state before feeding. When the positive electrode active material is applied to the battery system, the molar contents of Li may change after charge-discharge cycles. In the examples of positive electrode active materials such as LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4 in this application, the molar contents of oxygen (O) are only theoretical values. Lattice oxygen release can cause changes in the molar contents of oxygen (O). In reality, the molar contents of oxygen (O) may fluctuate, and all of the above situations are within the scope of protection of this application.

[0409] In the embodiments of this application, the elemental content in the positive electrode active material is defined in a way known in the art and can be detected using equipment and methods known in the art. For example, referring to EPA 6010D-2014, it can be tested by inductively coupled plasma atomic emission spectrometry (ICP-OES, instrument model: Thermo ICAP7400). After discharging the battery cell to 0% state of charge (SOC), the positive electrode sheet is disassembled, cleaned with dimethyl carbonate (DMC), dried, and then calcined at high temperature to remove impurities. 0.4 g of the positive electrode active material is weighed and 10 ml (50% concentration) of aqua regia is added. It is then placed on a plate at 180°C for 30 min. After digestion on the plate, the volume is adjusted to 100 mL, and quantitative testing is performed using a standard curve method.

[0410] In some embodiments, the positive electrode active material layer further includes a positive electrode additive, which may also include lithium elements. During the charging process of the battery cell, lithium ions can be released to compensate for lithium loss, which is beneficial to improving the capacity characteristics and cycle performance of the battery cell.

[0411] In some embodiments, the average longest diameter of the cathode additive is 2 μm to 5 μm, for example, 2 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, or any combination thereof. When cathode additives with the above particle size are used, lithium loss can be effectively compensated while effectively improving the stability of the cathode additive.

[0412] In this embodiment, the positive electrode sheet is cut along its thickness to expose the longitudinal section of the positive electrode active material layer. Scanning electron microscopy (SEM) is used to test the longitudinal section of the positive electrode active material layer to determine the longest diameter of the positive electrode additive particles and the longest diameter of the lithium phosphate-containing particles. For example, the "longest diameter" of a particle refers to the longest straight line passing through the center point of the particle and extending to its outer periphery.

[0413] In a cross-section along the thickness of the positive electrode active material layer, the longest diameters of multiple, for example, 10 lithium-containing iron oxides are counted, and their average value is the average longest diameter.

[0414] In some embodiments, the mass percentage of the cathode additive, based on the total mass of the cathode active material layer, is 0.2% to 2%, for example, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, or any combination thereof. Using cathode additives within this mass range effectively compensates for lithium loss.

[0415] In some embodiments, the positive electrode active material layer may optionally include a positive electrode conductive agent. This application embodiment does not particularly limit the type of positive electrode conductive agent; as an example, the positive electrode conductive agent includes at least one selected from superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass content of the positive electrode conductive agent is ≤5% based on the mass of the positive electrode active material layer.

[0416] In some embodiments, the positive electrode active material layer may optionally include a positive electrode binder. This application does not impose particular limitations on the type of positive electrode binder. As an example, the positive electrode binder may include at least one selected from polyvinylidene fluoride, polytetrafluoroethylene, a terpolymer of vinylidene fluoride-tetrafluoroethylene-propylene, a terpolymer of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, a tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and fluorinated acrylate resins. In some embodiments, the mass content of the positive electrode binder is ≤5% based on the mass of the positive electrode active material layer.

[0417] In some embodiments, the positive current collector may be a metal foil or a composite current collector. Examples of metal foils include at least one foil selected from aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The composite current collector may include a polymer base material and a metal material layer formed on at least one surface of the polymer base material. As an example, the metal material layer may include at least one selected from aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymer base material may include at least one selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0418] In some embodiments, the ratio of the thickness of the single-sided positive electrode active material layer to the thickness of the positive electrode current collector is 3 to 10, for example, 3, 4, 5, 6, 7, 8, 9, 10, or any two of the above values. Optionally, the ratio of the thickness of the single-sided positive electrode active material layer to the thickness of the positive electrode current collector is 4 to 8.

[0419] When the ratio of the thickness of the positive electrode active material layer on one side to the thickness of the positive electrode current collector is within the above range, the fast charging capability and energy density of the battery cell can be improved.

[0420] In some embodiments, the thickness of the positive current collector is 12 μm to 16 μm, optionally 13 μm to 15 μm. Exemplarily, the thickness of the positive current collector is 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, or a range consisting of any two of the above values.

[0421] When the thickness of the positive electrode current collector is within the above range, the current carrying capacity of the positive electrode current collector is excellent, and it can enable the battery cell to have a high energy density.

[0422] In the embodiments of this application, the thickness of the positive electrode active material layer and the positive electrode current collector are known in the art and can be detected using equipment and methods known in the art. For example, the thickness of the positive electrode sheet can be measured with a micrometer, the film layer on the surface of the positive electrode current collector can be removed, and the thickness of the positive electrode current collector can be measured with a micrometer. When the positive electrode active material layer is coated on one side, the thickness of the positive electrode active material layer is the thickness of the positive electrode sheet minus the thickness of the positive electrode current collector. When the positive electrode active material layer is coated on both sides, the thickness of the positive electrode active material layer is (the thickness of the positive electrode sheet minus the thickness of the positive electrode current collector) / 2.

[0423] The positive electrode active material layer is typically formed by coating a positive electrode slurry onto the positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing the positive electrode active material, optional conductive agent, optional binder, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to it.

[0424] The positive electrode sheet does not exclude additional functional layers besides the positive electrode active material layer. For example, in some embodiments, the positive electrode sheet of this application embodiment further includes a positive electrode conductive layer sandwiched between the positive electrode current collector and the positive electrode active material layer and disposed on the surface of the positive electrode current collector. In other embodiments, the positive electrode sheet of this application embodiment further includes a protective layer covering the surface of the positive electrode active material layer.

[0425] Figure 21 is a cross-sectional schematic diagram of the negative electrode sheet of a battery cell provided in some embodiments of this application.

[0426] In some embodiments, for the purpose of more clearly illustrating this application, the electrode body 15 of the negative electrode 14 is defined as the negative electrode body 15d, the tab 16 of the negative electrode 14 is defined as the negative electrode tab 16d, the active material layer 151 of the negative electrode 14 is defined as the negative active material layer 151b containing negative active material, and the current collector 152 of the negative electrode 14 is defined as the negative current collector 152d.

[0427] In some embodiments, the negative electrode sheet 14 includes a negative electrode current collector 152d and a negative electrode active material layer 151b disposed on at least one surface of the negative electrode current collector 152d and comprising a negative electrode active material. For example, the negative electrode current collector 152d has two surfaces opposite to each other in its thickness direction, and the negative electrode active material layer 151b is disposed on either or both of the two opposite surfaces of the negative electrode current collector 152d.

[0428] In some embodiments, the compaction density of the negative electrode active material layer of the battery cell at 0% state of charge (SOC) is 1.30 g / cm³. 3 Up to 1.65 g / cm 3 ; 1.35g / cm³ is optional 3 Up to 1.50 g / cm 3 For example, the compaction density of the negative electrode active material layer of the battery cell at 0% charge is 1.3 g / cm³. 3 1.32g / cm 3 1.35g / cm 3 1.40g / cm 3 1.45g / cm 3 1.50g / cm 3 1.55g / cm 3 1.60g / cm3 1.65g / cm 3 Or a range consisting of any two of the above values.

[0429] When the compaction density of the negative electrode active material layer is within the above range, it is beneficial to improve the energy density of the battery cell. Furthermore, since the negative electrode active material layer is densely packed, the contact resistance between particles is small, which can further reduce the resistance of the electrode, thereby reducing heat generation, alleviating the problem of aggravated negative electrode side reactions caused by heat accumulation, and improving the cycle performance of the battery cell.

[0430] In this embodiment, the compaction density of the negative electrode active material layer of the battery cell at 0% state of charge (SOC) is a term known in the art and can be detected using equipment and methods known in the art, such as the compaction density test method of the positive electrode active material layer described above.

[0431] In some embodiments, the single-sided coating weight of the negative electrode active material layer is 120 mg / 1540.25 mm. 2 Up to 180mg / 1540.25mm 2 The option is 125mg / 1540.25mm. 2 Up to 150mg / 1540.25mm 2 For example, the single-sided coating weight of the negative electrode active material layer is 120 mg / 1540.25 mm. 2 122mg / 1540.25mm 2 125mg / 1540.25mm 2 128mg / 1540.25mm 2 130mg / 1540.25mm 2 132mg / 1540.25mm 2 135mg / 1540.25mm 2 137mg / 1540.25mm 2 140mg / 1540.25mm 2 145mg / 1540.25mm 2 150mg / 1540.25mm 2 155mg / 1540.25mm 2 160mg / 1540.25mm 2 165mg / 1540.25mm 2 170mg / 1540.25mm 2 175mg / 1540.25mm 2 180mg / 1540.25mm 2Or a range consisting of any two of the above values.

[0432] When the single-sided coating weight of the negative electrode active material layer is within the above range, the heat generation per unit area of ​​the negative electrode sheet will not be too large, which alleviates the problem of aggravated negative electrode side reactions caused by heat accumulation, improves the cycle performance of the battery cell, and can also improve the energy density of the battery cell.

[0433] In the embodiments of this application, the single-sided coating weight of the negative electrode active material layer has a meaning known in the art and can be detected using equipment and methods known in the art, such as the single-sided coating weight test method of the film layer described above.

[0434] In some embodiments, the active material layer of the negative electrode sheet includes a carbon-based material, which has high cycle stability and can improve the cycle performance of the battery cell.

[0435] Optionally, the carbon-based material includes artificial graphite, which has excellent electrical conductivity, can reduce the heat generation of the negative electrode sheet, reduce the heat generation of the battery cell, and improve the fast charging performance of the battery cell.

[0436] In some embodiments, the positive electrode active material is mainly a lithium phosphate system with an olivine structure, and the negative electrode active material is mainly a carbon-based material system. When used together, the cycle performance of the battery cell is relatively excellent.

[0437] In some embodiments, the carbon-based material may further include natural graphite. Specifically, the carbon-based material may include artificial graphite, or it may include both artificial and natural graphite. Natural graphite has relatively good electrical conductivity, which helps to further reduce heat generation and improve the power performance and cycle performance of the battery cell.

[0438] In some embodiments, the negative electrode active material layer may include, in addition to the carbon-based materials described above, at least one of silicon-based materials, tin-based materials, and lithium titanate. Tin-based materials may include at least one of elemental tin, tin oxide, and tin alloy materials. Optionally, silicon-based materials may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy materials.

[0439] The qualitative and quantitative analysis of each substance or element in this application can be performed using suitable equipment and methods known to those skilled in the art. Relevant testing methods can be referenced from domestic and international testing standards and enterprise standards. Furthermore, those skilled in the art can adaptively modify certain testing steps / instrument parameters from the perspective of testing accuracy to obtain more accurate results. One testing method can be used for qualitative or quantitative analysis, or several testing methods can be used in combination for qualitative or quantitative determination.

[0440] For example, this application can combine JIS / K0131-1996 General Rules for X-ray Diffraction Analysis to perform X-ray powder diffraction tests and qualitative analysis on negative electrode sheets or negative electrode active materials.

[0441] Artificial graphite and natural graphite can be distinguished by SEM cross-sectional images taken by scanning electron microscope (SEM). Natural graphite has gaps between the sheet-like structures in its SEM cross-section, while artificial graphite has a dense structure with no obvious gaps. Alternatively, they can be distinguished by XRD patterns obtained by X-ray diffraction. Natural graphite has obvious 2H and 3R phases in its XRD pattern, while artificial graphite only has the 2H phase in its XRD pattern.

[0442] In the embodiments of this application, the negative electrode active material layer includes at least one film layer, which can be a single film layer or at least two film layers. Optionally, the negative electrode active material layer includes at least two film layers.

[0443] When a single-layer film is used for the negative electrode active material layer, the negative electrode active material in the negative electrode active material layer includes a carbon-based material. When a single-layer film is used, the volume average particle size Dv50 of the carbon-based material is 8 μm to 13 μm, optionally 9.5 μm to 11.5 μm. Exemplarily, the volume average particle size Dv50 of the carbon-based material is 8 μm, 8.5 μm, 8.8 μm, 9 μm, 9.2 μm, 9.5 μm, 9.8 μm, 10 μm, 10.2 μm, 10.5 μm, 10.8 μm, 11 μm, 11.2 μm, 11.5 μm, 11.8 μm, 12 μm, 12.2 μm, 12.5 μm, 12.8 μm, 13 μm, or a range consisting of any two of the above values.

[0444] When the negative electrode active material layer employs at least two film layers, the negative electrode active material in the negative electrode active material layer includes a carbon-based material. The negative electrode active material layer may include two, three, four, or even more film layers.

[0445] In some embodiments, the negative electrode active material layer 151b includes a first negative electrode film layer 1511 and a second negative electrode film layer 1512. The first negative electrode film layer 1511 is disposed on the surface of the negative electrode current collector 152d, and the second negative electrode film layer 1512 is disposed on the side of the first negative electrode film layer 1511 opposite to the negative electrode current collector 152d.

[0446] In some embodiments, both the first negative electrode film layer 1511 and the second negative electrode film layer 1512 comprise carbon-based materials.

[0447] In some embodiments, the carbon-based material of the first negative electrode film layer 1511 includes artificial graphite.

[0448] In some embodiments, the carbon-based material of the second negative electrode film layer 1512 includes artificial graphite. The artificial graphite in the first negative electrode film layer 1511 and the artificial graphite in the second negative electrode film layer 1512 may be the same or different. When the artificial graphite in the first negative electrode film layer 1511 and the artificial graphite in the second negative electrode film layer 1512 are different, it may be due to different particle sizes or different degrees of graphitization.

[0449] The interface between the first negative electrode film layer 1511 and the second negative electrode film layer 1512 can be regular or irregular, and optionally irregular.

[0450] The negative electrode active material layer 151b comprises at least two film layers, and the layered coating is beneficial to improving the fast charging performance of the battery cell 7. In particular, when there is a difference between the first negative electrode film layer 1511 and the second negative electrode film layer 1512, it is possible to construct a porosity difference in the negative electrode active material layer 151b, reduce the tortuosity of lithium-ion transport, and improve the fast charging performance of the battery cell 7.

[0451] In some embodiments, the volume average particle size Dv50 of the carbon-based material in the first negative electrode film layer 1511 is greater than or equal to the volume average particle size Dv50 of the carbon-based material in the second negative electrode film layer 1512. Further optionally, having a larger volume average particle size Dv50 in the carbon-based material of the first negative electrode film layer 1511 than in the second negative electrode film layer 1512 is beneficial for improving the kinetic performance of the negative electrode active material layer 151b.

[0452] The difference in particle size between the first negative electrode film layer 1511 and the second negative electrode film layer 1512 can improve the fast charging performance of the battery cell 7. Specifically, during fast charging, the overpotential of the second negative electrode film layer 1512 is usually high, and the bottleneck of fast charging is mainly the second negative electrode film layer 1512. However, in the embodiment of this application, the particle size of the second negative electrode film layer 1512 is relatively small, which can shorten the solid phase transport path of lithium ions, improve the fast charging performance, and improve the lithium deposition problem on the surface of the negative electrode sheet 14.

[0453] Optionally, the carbon-based material of the first negative electrode film layer 1511 is particulate, and its volume average particle size Dv50 is 9.0 μm to 18.5 μm, optionally 9.0 μm to 14.6 μm. Exemplarily, the volume average particle size of the carbon-based material of the second negative electrode film layer 1512 is 9.0 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 14.6 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, or any range of two of the above values. When the first negative electrode film layer 1511 includes a carbon-based material, the volume average particle size Dv50 of the carbon-based material in the first negative electrode film layer 1511 is 9.0 μm to 18.5 μm, and can be selected as 9.0 μm to 14.6 μm.

[0454] When the volume average particle size Dv50 of the carbon-based material in the first negative electrode film layer 1511 is within the above range, it can shorten the solid-phase transport path of lithium ions and improve fast charging performance. On the other hand, the material is less prone to agglomeration during the preparation process, which can improve the stability of the material.

[0455] Optionally, the carbon-based material of the second negative electrode film 1512 is particulate, with a volume average particle size Dv50 of 7.8 μm to 14.3 μm, optionally 7.8 μm to 11.3 μm. For example, the volume average particle size Dv50 of the carbon-based material is 7.8 μm, 8.0 μm, 8.2 μm, 8.5 μm, 8.8 μm, 9 μm, 9.2 μm, 9.5 μm, 9.8 μm, 10 μm, 10.2 μm, 10.5 μm, 10.8 μm, 11 μm, 11.3 μm, 11.2 μm, 11.5 μm, 11.8 μm, 12 μm, 12.2 μm, 12.5 μm, 12.8 μm, 13 μm, 13.2 μm, 13.5 μm, 13.8 μm, 14 μm, 14.1 μm, 14.3 μm, or a range of any two of the above values. When the second negative electrode film layer 1512 includes a carbon-based material, the volume average particle size Dv50 of the carbon-based material in the second negative electrode film layer 1512 is 7.8 μm to 14.3 μm, and can be selected as 7.8 μm to 11.3 μm.

[0456] When the volume average particle size Dv50 of the carbon-based material in the second negative electrode film 1512 is within the above range, it can shorten the solid-phase transport path of lithium ions and improve fast charging performance.

[0457] When the volume average particle size Dv50 of the carbon-based material in the second negative electrode film layer 1512 is within the above-mentioned range, it can shorten the solid-phase transport path of lithium ions and improve fast charging performance. On the other hand, the material is less prone to agglomeration during the preparation process, which can improve the stability of the material. Furthermore, the combination of the negative electrode active material in the second negative electrode film layer 1512 and the negative electrode active material in the first negative electrode film layer 1511 within the above-mentioned volume average particle size range is beneficial to constructing a gradient porosity difference between the second negative electrode film layer 1512 and the first negative electrode film layer 1511, reducing the tortuosity of lithium ion transport, and improving the fast charging performance of the battery cell 7.

[0458] In the embodiments of this application, the volume average particle size Dv50 of the negative electrode active material has a well-known meaning in the art and can be detected using well-known equipment and methods in the art. For example, the negative electrode active material can be used as a sample, and the Dv50 of the particles can be tested using a Mastersizer 2000E laser particle size analyzer according to the test standard GB / T 19077-2016.

[0459] Optionally, the carbon-based material of the first negative electrode film layer 1511 may also include natural graphite.

[0460] For example, the carbon-based material of the first negative electrode film layer 1511 includes at least one of artificial graphite and natural graphite, and the carbon-based material of the second negative electrode film layer 1512 includes artificial graphite.

[0461] In other embodiments, the volume average particle size Dv50 of the carbon-based material in the second negative electrode film layer 1512 is greater than the volume average particle size Dv50 of the carbon-based material in the first negative electrode film layer 1511. Further optionally, having a larger volume average particle size Dv50 in the carbon-based material of the second negative electrode film layer 1512 than the volume average particle size Dv50 in the first negative electrode film layer 1511 is beneficial for increasing the compaction density of the negative electrode active material layer 151b.

[0462] The particle size of the first negative electrode film layer 1511 and the second negative electrode film layer 1512 is different, which can improve the fast charging performance of the battery cell 7.

[0463] For example, the carbon-based material of the second negative electrode film layer 1512 includes at least one of artificial graphite and natural graphite, and the carbon-based material of the first negative electrode film layer 1511 includes artificial graphite.

[0464] In some embodiments, the negative electrode active material layer 151b may optionally include a negative electrode conductive agent. This application embodiment does not particularly limit the type of negative electrode conductive agent. As an example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass content of the negative electrode conductive agent is ≤5% based on the total weight of the negative electrode active material layer 151b.

[0465] In some embodiments, the negative electrode active material layer 151b may optionally include a negative electrode binder. In some embodiments, the mass content of the negative electrode binder is ≤5% based on the total weight of the negative electrode active material layer 151b.

[0466] In some embodiments, the negative electrode active material layer 151b may optionally include other additives. As examples, other additives may include thickeners, dispersants, etc., such as sodium carboxymethyl cellulose (CMC-Na), PTC thermistor materials, etc. In some embodiments, the mass content of other additives is ≤2% based on the total weight of the negative electrode active material layer 151b.

[0467] In some embodiments, the negative current collector 152d may be a metal foil or a composite current collector. Examples of metal foils include at least one foil made of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The composite current collector may include a polymer base layer and a metal material layer formed on at least one surface of the polymer base layer. As an example, the metal material layer may include at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymer base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0468] In some embodiments, the ratio of the thickness of the single-sided negative electrode active material layer to the thickness of the negative electrode current collector is 8 to 14, for example, 8, 9, 10, 11, 12, 13, 14 or any two of the above values. Optionally, the ratio of the thickness of the single-sided negative electrode active material layer to the thickness of the negative electrode current collector is 10 to 12.

[0469] When the ratio of the thickness of the single-sided negative electrode active material layer to the thickness of the negative electrode current collector is within the above range, the fast charging capability and energy density of the battery cell can be improved.

[0470] In some embodiments, the thickness of the negative current collector is 5 μm to 10 μm, optionally 6 μm to 8 μm. Exemplarily, the thickness of the negative current collector is 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, or a range consisting of any two of the above values.

[0471] When the thickness of the negative electrode current collector is within the above range, the current carrying capacity of the negative electrode current collector is excellent, and it can enable the battery cell to have a high energy density.

[0472] In the embodiments of this application, the thickness of the negative electrode current collector has a meaning known in the art and can be detected using equipment and methods known in the art. For example, the film layer on the surface of the negative electrode current collector can be washed away with a solvent, and the thickness of the negative electrode current collector can be measured with a micrometer.

[0473] The negative electrode active material layer is typically formed by coating a negative electrode slurry onto the negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is usually formed by dispersing the negative electrode active material, optional conductive agent, optional binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0474] The negative electrode sheet does not exclude additional functional layers besides the negative electrode active material layer. For example, in some embodiments, the negative electrode sheet of this application embodiment further includes a negative electrode conductive layer sandwiched between the negative electrode current collector and the negative electrode active material layer and disposed on the surface of the negative electrode current collector. In other embodiments, the negative electrode sheet of this application embodiment further includes a protective layer covering the surface of the negative electrode active material layer.

[0475] In some embodiments, during the charging and discharging process of a single battery cell, active ions, such as lithium ions, are inserted and extracted back and forth between the positive and negative electrode plates, and the electrolyte plays a role in conducting active ions between the positive and negative electrode plates.

[0476] The electrolyte salt includes lithium salts, including lithium bis(fluorosulfonyl)imide, and may further include lithium hexafluorophosphate (LiPF6). These lithium salts are beneficial for improving the lithium-ion conductivity of the electrolyte and enhancing the fast-charging capability of individual battery cells.

[0477] Optionally, based on the mass of the electrolyte, the mass ratio of lithium hexafluorophosphate to lithium difluorosulfonylimide is 0.5 to 4, optionally 1.2 to 2.0. Lithium salts are beneficial for improving the lithium-ion conductivity of the electrolyte and enhancing the fast-charging capability of individual battery cells.

[0478] For example, the mass content of lithium hexafluorophosphate and the mass content of lithium difluorosulfonylimide are 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, 1.7, 1.9, 2.1, 2.3, 2.5, 2.7, 2.9, 3.1, 3.3, 3.5, 3.7, 3.9, 4.0 or any combination of the above values.

[0479] In the embodiments of this application, the mass content of lithium bis(fluorosulfonyl)imide is 1% to 15%, and optionally 3% to 12%, based on the mass of the electrolyte.

[0480] For example, based on the mass of the electrolyte, the mass content of lithium difluorosulfonylimide is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any combination of two of the above values.

[0481] In some embodiments, the mass content of lithium salt is 13% to 20% based on the mass of the electrolyte, for example, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or a range of any two of the above values.

[0482] In some embodiments, the electrolyte has a conductivity of 10 mS / cm to 13 mS / cm at room temperature. Exemplarily, the electrolyte conductivity at room temperature is 10 mS / cm, 10.5 mS / cm, 11 mS / cm, 11.5 mS / cm, 12 mS / cm, 12.5 mS / cm, 13 mS / cm, or any range of two of the above values.

[0483] When the conductivity of the electrolyte at room temperature, such as 25°C, is within the above range, the migration rate of lithium ions in the electrolyte is relatively high, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation and improving the fast charging performance of the battery cell.

[0484] In the embodiments of this application, the conductivity of the electrolyte at room temperature, such as 25°C, is the ionic conductivity, which can be detected using equipment and methods known in the art, such as by referring to industry standard HG-T 4067-2015.

[0485] In some embodiments, the organic solvent includes carbonate solvents.

[0486] Optionally, the carbonate solvent in the electrolyte comprises 10% to 80% by mass. For example, the carbonate solvent in the organic solvent comprises 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80%, or any combination of two of the above values ​​by mass. The carbonate solvent at the above mass contents can further improve the conductivity of the electrolyte at room temperature, which is beneficial for lithium-ion migration and enhances the fast-charging performance of the battery cells.

[0487] Optionally, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. More preferably, the carbonate solvent includes one or more of dimethyl carbonate and ethylene carbonate. Even more preferably, the carbonate solvent includes dimethyl carbonate. The combined use of the above-mentioned carbonate solvents and chain carboxylic acid ester solvents improves the conductivity of the electrolyte at room temperature, which is beneficial for lithium-ion migration and enhances the fast-charging performance of the battery cells.

[0488] In some embodiments, the organic solvent includes chain carboxylic acid ester solvents.

[0489] Optionally, the chain carboxylic acid ester solvent has a mass content of 5% to 30% in the electrolyte. For example, the mass content of the chain carboxylic acid ester solvent is 5%, 10%, 15%, 20%, 25%, 30%, or any combination of two of the above values.

[0490] When the mass content of chain carboxylic acid ester solvents is within the above range, the viscosity of the electrolyte system is relatively low, which is conducive to the migration of lithium ions and improves the fast charging performance of the battery cells.

[0491] In some embodiments, the chain carboxylic acid ester solvent includes compounds represented by Formula I.

[0492] In formula I,

[0493] R1 includes a hydrogen atom, a C1 to C5 alkyl group, or a C1 to C5 haloalkyl group.

[0494] R2 includes C1 to C5 alkyl or C1 to C5 haloalkyl.

[0495] The aforementioned chain-like carboxylic acid ester solvents have high conductivity, which is beneficial for improving the fast charging capability of battery cells.

[0496] Optionally, R1 includes a hydrogen atom, a C1 to C3 alkyl group, or a C1 to C3 haloalkyl group. Further optionally, R1 includes a hydrogen atom, a halogen atom, a C1 to C2 alkyl group, or a C1 to C2 haloalkyl group.

[0497] Optionally, R2 comprises a C1 to C3 alkyl group or a C1 to C3 haloalkyl group. More optionally, R2 comprises a C1 to C2 alkyl group or a C1 to C2 haloalkyl group.

[0498] In the above embodiments, the halogenated alkyl group includes one or more of fluoroalkyl, chloroalkyl, bromoalkyl and iodoalkyl groups, and optionally, the halogenated alkyl group includes fluoroalkyl.

[0499] For example, the chain carboxylic acid ester solvent includes one or more compounds of formula I-1 to formula I-8.

[0500] In some embodiments, the electrolyte may further include additives, which may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, additives that improve battery low-temperature power performance, etc.

[0501] In some embodiments, the additive comprises one or more of carbonate additives and sulfur-containing additives, optionally at least two. These additives can improve the interfacial film performance on the positive and / or negative electrode sides, which is beneficial for improving the fast-charging performance of individual battery cells and enhancing cycle performance.

[0502] In some embodiments, the additive content in the electrolyte is 0.5% to 6% by mass. Exemplarily, the additive content in the electrolyte is 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6%, or a range of any two of the above values.

[0503] The aforementioned organic solvents, such as chain carboxylic acid esters, may decompose and produce acid at high temperatures, which can corrode the solid electrolyte interphase (SEI) film on the surface of the negative electrode. However, the additives can form a dense and uniformly thick SEI film on the negative electrode side, which can effectively repair the SEI film, provide excellent protection for the negative electrode active material, and help improve the fast charging performance of the battery cell and improve cycle performance.

[0504] For example, the carbonate additives include one or more of vinylene carbonate (VC) and fluoroethylene carbonate (FEC), and optionally, the carbonate additives include vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0505] Vinylene carbonate (VC) can form a dense and uniformly thick SEI film on the negative electrode side, effectively repairing the SEI film and providing excellent protection for the negative electrode active material, which is beneficial to improving the fast charging performance and cycle performance of the battery cell.

[0506] Fluorinated ethylene carbonate (FEC) can form a SEI film with relatively low impedance on the negative electrode side, effectively repairing the SEI film and providing excellent protection for the negative electrode active material, which is beneficial to improving the fast charging performance and cycle performance of the battery cell.

[0507] For example, the sulfur-containing additive includes one or more of vinyl sulfate DTD, vinyl disulfate 2-DTD, butenyl sulfite BS, 1,3-propanesulfonate lactone PS, vinyl sulfite ES, and methylene disulfonate MMDS, optionally 1,3-propanesulfonate lactone PS.

[0508] Sulfur-containing additives can effectively repair the SEI film, provide excellent protection for the negative electrode active material, and help improve the fast charging performance and cycle performance of battery cells.

[0509] For example, the additives include one or more of vinylene carbonate, fluoroethylene carbonate, and 1,3-propanesulfonyl lactone.

[0510] Optionally, the mass content of vinylene carbonate (VC) in the electrolyte is from 0.5% to 3.0%, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.5%, 3.0%, or any combination of two of the above values. When the mass content of vinylene carbonate (VC) in the electrolyte is within the above range, it can effectively repair the SEI film, provide excellent protection for the negative electrode active material, and help improve the fast charging performance and cycle performance of the battery cell.

[0511] Optionally, the mass content of fluoroethylene carbonate (FEC) in the electrolyte is from 0.2% to 2.5%, for example, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.5%, 2.0%, 2.5%, or any combination of two of the above values. When the mass content of fluoroethylene carbonate (FEC) in the electrolyte is within the above range, it can effectively repair the SEI film, provide excellent protection for the negative electrode active material, and help improve the fast charging performance and cycle performance of the battery cell.

[0512] Optionally, the mass content of 1,3-propanesulfonyl lactone (PS) in the electrolyte is from 0.5% to 2.5%, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.5%, or any combination of two of the above values. When the mass content of 1,3-propanesulfonyl lactone (PS) in the electrolyte is within the above range, it can effectively repair the SEI film, provide excellent protection for the negative electrode active material, and help improve the fast charging performance and cycle performance of the battery cell.

[0513] In the embodiments of this application, the types and contents of inorganic components / lithium salts in the electrolyte are known in the art and can be detected using equipment and methods known in the art. For example, the inorganic components / lithium salts in the electrolyte can be qualitatively or quantitatively analyzed by ion chromatography analysis method according to standard JY / T020-1996 "General Rules for Ion Chromatography Analysis". In the embodiments of this application, freshly prepared electrolyte can be used as a sample, the free electrolyte of a fresh battery can be used as a sample, or a battery that has been completely discharged (discharged to the lower limit cutoff voltage so that the battery's state of charge is about 0% SOC) can be disassembled in reverse, and the free electrolyte obtained from the battery can be used as a sample for detection by ion chromatography analysis method.

[0514] In the embodiments of this application, the types and contents of organic components in the electrolyte are known in the art and can be detected using equipment and methods known in the art. For example, the organic components in the electrolyte can be qualitatively and quantitatively analyzed by gas chromatography using GB / T9722-2006 "General Rules for Gas Chromatography of Chemical Reagents".

[0515] In this embodiment, after quantitative and qualitative detection of each component in the electrolyte, the components are classified. Chain-like carboxylic acid ester solvents and carbonate solvents (e.g., ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate) are considered as components of the organic solvent. The mass content of each component is calculated based on the electrolyte mass as 100%.

[0516] Carbonate additives (such as vinylene carbonate and fluoroethylene carbonate) and sulfur-containing additives are used as additives in the electrolyte. The mass content of each component is calculated based on the mass of the electrolyte as 100%.

[0517] Figure 22 is an exploded view of a battery cell provided in some other embodiments of this application; Figure 23 is a schematic diagram of the electrode of a battery cell provided in some embodiments of this application in an unfolded state.

[0518] Referring to Figures 22 and 23, in some embodiments, the battery cell 7 is a cylindrical battery cell, with the first direction X parallel to the axial direction of the battery cell 7. Cylindrical battery cells have advantages such as mature manufacturing processes, good consistency, good heat dissipation performance, and high assembly efficiency.

[0519] The electrode assembly 10 has a wound structure. The second direction Y can be the winding direction of the electrode assembly 10.

[0520] In some embodiments, the housing 20 includes a first end wall 211, a second end wall 20a, and a side wall 212. The first end wall 211 and the second end wall 20a are disposed along a first direction X, and the side wall 212 connects the first end wall 211 and the second end wall 20a.

[0521] In some embodiments, the housing 20 includes a first end wall 211, a second end wall 20a, and a side wall 212, wherein the first end wall 211 and the second end wall 20a are respectively disposed at both ends of the side wall 212 along the first direction X.

[0522] For example, the housing 21 includes a sidewall 212. At least one of the first end wall 211 and the second end wall 20a is formed independently of the sidewall 212.

[0523] In some examples, the first end wall 211 and the side wall 212 are integrally formed. Optionally, the housing 21 includes the first end wall 211 and the side wall 212. In other examples, the first end wall 211 and the side wall 212 are formed independently and are fixedly connected by welding, snap-fitting, bonding or other means. Optionally, the housing 21 includes the side wall 212 and the first end wall 211 is an end cap 22.

[0524] In some examples, the second end wall 20a is integrally formed with the side wall 212. Optionally, the housing 21 includes the second end wall 20a and the side wall 212. In other examples, the second end wall 20a and the side wall 212 are formed independently and are fixedly connected by welding, snap-fitting, bonding or other means. Optionally, the housing 21 includes the side wall 212 and the second end wall 20a is an end cap 22.

[0525] In some embodiments, the housing 21 includes an integrally formed first end wall 211 and side wall 212, and the second end wall 20a is an end cap 22.

[0526] In some embodiments, the battery cell 7 includes an electrode terminal 30 with an insulated first end wall 211. One of the tabs 16 of the first electrode 11 and the tabs 16 of the second electrode 12 is electrically connected to the first end wall 211, and the other is electrically connected to the electrode terminal 30.

[0527] One of the electrode terminal 30 and the first end wall 211 is used as the first electrode terminal 30a, and the other is used as the second electrode terminal 30b.

[0528] The first end wall 211 and the electrode terminal 30 can serve as two electrodes of the battery cell 7 and are located on the same side of the battery cell 7. When multiple battery cells 7 are assembled into a group, it is convenient to connect the busbar to the first end wall 211 or the busbar to the electrode terminal 30, thus simplifying the structure of the battery device.

[0529] In some embodiments, the first electrode ear 16a is electrically connected to the first electrode terminal 30a via the first adapter 40a, and the second electrode ear 16b is electrically connected to the first end wall 211 via the second adapter 40b.

[0530] For example, electrode terminal 30 is a first electrode terminal 30a, and first end wall 211 is a second electrode terminal 30b.

[0531] In some embodiments, at least one of the sidewall 212 and the second endwall 20a is connected to the second adapter 40b so that the sidewall 212 electrically connects the first endwall 211 and the second adapter 40b.

[0532] In some examples, the second adapter 40b is connected to the sidewall 212, and the second electrode ear 16b is electrically connected to the first end wall 211 via the second adapter 40b and the sidewall 212. The second adapter 40b may be electrically connected to or insulated from the second end wall 20a. In other examples, the second adapter 40b is electrically connected to the second end wall 20a, and the second electrode ear 16b is electrically connected to the first end wall 211 via the second adapter 40b, the second end wall 20a, and the sidewall 212. Optionally, the second adapter 40b is soldered to the second end wall 20a.

[0533] In some embodiments, the first electrode 11 includes a plurality of first electrode tabs 16a. The ends of the plurality of first electrode tabs 16a away from the first electrode body 15a are bent by a flattening or smoothing process and formed into a multilayer structure stacked in the first direction X.

[0534] In some embodiments, the electrode body 15 of the first electrode 11 includes a coating area 153 and a transition area 154 arranged along the first direction X. An active material layer 151 is disposed in the coating area 153. The transition area 154 and the tab 16 are not provided with an active material layer 151. The transition area 154 connects the coating area 153 and the tab 16.

[0535] The first electrode 11 also includes an insulating element 19, at least a portion of which is disposed in the transition region 154.

[0536] In some embodiments, along the first direction X, the first electrode tab 16a is spaced apart from the insulating member 19.

[0537] Figure 24 is a partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application;

[0538] Referring to FIG24, in some embodiments, the sidewall 212 is provided with an inwardly protruding protrusion 2121, and the battery cell 7 further includes an adapter 40, which is located on one side of the electrode assembly 10 along the first direction X and connected to the protrusion 2121. One of the tabs 16 of the first electrode 11 and the tabs 16 of the second electrode 12 is disposed at the end of the electrode assembly 10 facing the adapter 40 and connected to the adapter 40.

[0539] For example, the protrusion 2121 can be a solid structure or a hollow structure.

[0540] Connecting the adapter 40 to the protrusion 2121 can shorten the conductive path between the first end wall 211 and the tab 16, reduce resistance, reduce heat generation, and improve the cycle performance of the battery cell 7.

[0541] In some embodiments, the second electrode ear 16b is connected to the second adapter 40b, and the second adapter 40b is connected to the protrusion 2121. As an example, the second adapter 40b may be soldered to the protrusion 2121; alternatively, the second adapter 40b may also be crimped to the protrusion 2121.

[0542] In some embodiments, at least a portion of the protrusion 2121 is located between the second end wall 20a and the second tab 16b in the first direction X. The protrusion 2121 overlaps with the second tab 16b in the first direction X, which can restrict the movement of the second tab 16b in the first direction X when the battery cell 7 is subjected to external impact, thereby reducing the risk of connection failure between the second tab 16b and the second adapter 40b.

[0543] In some embodiments, a portion of the second adapter 40b is located on the side of the protrusion 2121 facing the second end wall 20a and is connected to the protrusion 2121. The second adapter 40b is connected to the protrusion 2121 from the outside of the protrusion 2121, which can reduce assembly difficulty.

[0544] In some embodiments, the second adapter 40b is welded to the protrusion 2121.

[0545] In some embodiments, the outer side of the sidewall 212 is provided with a recess 2122, which corresponds to the position of the protrusion 2121. As an example, after the electrode assembly 10 is installed into the housing 21, the sidewall 212 is pressed from the outside to form an inwardly protruding protrusion 2121.

[0546] In some embodiments, the sidewall 212 further includes a crimping portion 2123, which extends from the end of the protrusion 2121 away from the first endwall 211 and surrounds the end cap 22.

[0547] A portion of the crimping portion 2123 is bent to form a flange structure, and in the first direction X, a portion of the end cap 22 is located between the flange structure and the protrusion 2121. The protrusion 2121 and the flange structure can limit the end cap 22 to fix the end cap 22 in the first direction X.

[0548] According to some embodiments of this application, this application also provides a battery device including multiple battery cells of any of the above embodiments.

[0549] According to some embodiments of this application, this application also provides an electrical device, including a battery cell from any of the above embodiments, wherein the battery cell is used to provide electrical energy to the electrical device. The electrical device can be any of the aforementioned devices or systems that utilize battery cells.

[0550] Referring to Figures 3 to 9, an embodiment of this application provides a square-shell battery cell, which includes a shell 20, an electrode assembly 10, a first electrode terminal 30a, and a second electrode terminal 30b.

[0551] The electrode assembly 10 is housed within the housing 20. The electrode assembly 10 includes a plurality of first electrode plates 11 and a plurality of second electrode plates 12, which are alternately stacked. One of the first electrode plates 11 and the second electrode plates 12 is a positive electrode plate 13, and the other is a negative electrode plate 14.

[0552] The first electrode 11 and the second electrode 12 both include an electrode body 15 and a plurality of tabs 16. At least a portion of the electrode body 15 is provided with an active material layer 151, while at least a portion of the tabs 16 is not provided with an active material layer 151. The electrode body 15 and the tabs 16 are arranged along a first direction X, and the dimension of the tabs 16 along a second direction Y is less than or equal to the dimension of the electrode body 15 along the second direction Y. The first direction X, the second direction Y, and the thickness direction T of the electrode body 15 are perpendicular to each other. One of the first direction X and the second direction Y is parallel to the length direction Z2 of the battery cell 7, and the other is parallel to the width direction Z3 of the battery cell 7.

[0553] The active material layer 151 of the positive electrode 13 comprises a lithium phosphate with an olivine structure. The active material layer 151 of the negative electrode 14 comprises a carbon-based material.

[0554] Along the length direction Z2 of the battery cell 7, the size of the electrode body 15 is 320mm to 650mm.

[0555] The plurality of tabs 16 of the first electrode 11 are electrically connected to the first electrode terminal 30a, and the plurality of tabs 16 of the second electrode 12 are electrically connected to the second electrode terminal 30b.

[0556] The first electrode 11 satisfies: a 2 +b 2 The maximum value is 6000 to 110000; where a represents the distance along the first direction X between any point A of the electrode body 15 in the first electrode 11 and the electrode tab 16 closest to point A among all electrode tabs 16, and the unit of a is mm; b represents the distance along the second direction Y between point A of the first electrode 11 and the electrode tab 16 closest to point A among all electrode tabs 16, and the unit of b is mm.

[0557] The second electrode 12 satisfies: e 2 +f 2 The maximum value is between 6000 and 110000. e represents the distance along the first direction X between any point B of the electrode body 15 in the second electrode 12 and the electrode tab 16 closest to point B among all electrode tabs 16; the unit of e is mm. f represents the distance along the second direction Y between point B of the second electrode 12 and the electrode tab 16 closest to point B among all electrode tabs 16; the unit of f is mm.

[0558] Example

[0559] The following embodiments describe the contents disclosed in this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosures in this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0560] Example 1

[0561] 1. Preparation of positive electrode sheet

[0562] The positive electrode includes a positive electrode tab, a positive electrode current collector, and a positive electrode active material layer disposed on both sides of the positive electrode current collector. The positive electrode current collector is an aluminum foil with a thickness of 13μm.

[0563] The positive electrode active material layer includes lithium phosphate, lithium iron ferrite additive, polyvinylidene fluoride (PVDF) binder, and acetylene black conductive agent in a mass ratio of 96:1:2:1. The positive electrode active material layer is a film layer formed by uniformly coating the positive electrode slurry (solvent is N-methylpyrrolidone NMP) on both sides of the positive electrode current collector, and then drying and cold pressing it.

[0564] Lithium-containing phosphates include lithium iron phosphate.

[0565] The single-sided coating weight of the positive electrode active material layer is 300 mg / 1540.25 mm. 2 .

[0566] 2. Preparation of negative electrode sheet

[0567] The negative electrode sheet includes a negative electrode tab, a negative electrode current collector, and a negative electrode active material layer disposed on both sides of the negative electrode current collector. The negative electrode current collector is a copper foil with a thickness of 6μm.

[0568] The negative electrode active material layer is a film layer formed by uniformly coating the negative electrode slurry (solvent is deionized water) onto the surface of the negative electrode current collector, and then drying and cold pressing it.

[0569] The single-sided coating weight of the negative electrode active material layer is 130 mg / 1540.25 mm. 2 .

[0570] The negative electrode active material layer includes a first negative electrode film layer and a second negative electrode film layer. The first negative electrode film layer is located on the surface of the negative electrode current collector, and the second negative electrode film layer is located on the surface of the first negative electrode film layer.

[0571] The first negative electrode film layer includes carbon-based material, conductive agent acetylene black, negative electrode binder styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose in a mass ratio of 96.5:1:1.5:1. The carbon-based material of the first negative electrode film layer includes artificial graphite and natural graphite in a mass ratio of 1:1, and the volume average particle size of the carbon-based material is 9.0 μm.

[0572] The second negative electrode film layer includes carbon-based materials, conductive agent acetylene black, negative electrode binder styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose in a mass ratio of 96.5:1:1.5:1. The carbon-based materials of the second negative electrode film layer include artificial graphite, and the volume average particle size of the carbon-based materials is 8.0 μm.

[0573] 3. Isolation components

[0574] The separator includes a base film, which is a 7μm polyethylene film layer with a porosity of 42%.

[0575] 4. Preparation of electrolyte

[0576] The electrolyte consists of organic solvents, lithium salts, and additives.

[0577] The organic solvents include 10% chain carboxylic acid ester solvents (ethyl acetate) and 75% carbonate solvents (diethyl carbonate, dimethyl carbonate, and ethylene carbonate in a mass ratio of 1:1:1). The mass content of each component in the organic solvents is calculated based on the mass of the electrolyte.

[0578] Based on the mass of the electrolyte, the additive content is 1.5% by mass, which includes vinylene carbonate (VC).

[0579] The lithium salt comprises 8.5% lithium hexafluorophosphate (LiPF6) and 5% lithium difluorosulfonylimide.

[0580] The electrolyte has a conductivity of 12 mS / cm at room temperature.

[0581] 5. Preparation of battery cells

[0582] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation, resulting in a stacked electrode assembly. This assembly is then placed in an outer packaging shell, dried, and injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a battery cell is obtained. The compaction density of the positive electrode active material layer at 0% SOC is 2.5 g / cm³. 3 The compaction density of the negative electrode active material layer at 0% SOC is 1.45 g / cm³. 3 .

[0583] Comparative Examples 1-3, Examples 2 to 9

[0584] Battery cells were prepared using a method similar to that of Example 1. The difference from Example 1 is that the parameters of the positive electrode tab and the positive electrode active material layer in the positive electrode sheet were adjusted, as shown in Table 1.

[0585] Performance testing

[0586] 1. DC internal resistance (DCR) test of individual battery cells

[0587] You can refer to the methods in GB / T 31467 "Performance Test Specification for High-Power Lithium-ion Power Batteries for HEVs".

[0588] For example, at 25°C, charge a single battery cell to 3.65V with a constant current of 0.33C, let it stand for 1 minute, then charge it to 3.65V with a constant current of 0.05C, let it stand for 30 minutes, and then discharge it to 2.5V with a constant current of 0.33C. Record the discharge capacity A0 at this point in Ah. Then charge it to 0.5A0 Ah with a constant current of 0.33C and adjust the SOC to 50%.

[0589] After placing the battery cell at 25°C for 2 hours, it was discharged at a constant current of 4C for 10 seconds, and ΔU was recorded. 放电 ΔI 放电 The discharge DCR data of lithium-ion batteries can be calculated using the following formula, R. 放电 =ΔU 放电 / ΔI 放电 ,

[0590] Wherein, ΔU 放电 ΔI represents the voltage change within 10 seconds of the start of discharge. 放电 This indicates the current value within 10 seconds of the start of discharge.

[0591] The test results are shown in Table 1.

[0592] Table 1

[0593] In Table 1, the positive electrode tab is disposed on at least one side of the positive current collector along the first direction, and the negative electrode tab adopts a similar arrangement as the positive electrode tab.

[0594] The length of the positive electrode active material layer is equal to the length of the positive electrode body, and the width of the positive electrode active material layer is equal to the width of the positive electrode body.

[0595] In Table 1, a represents the maximum distance between the electron and the closest point to the electrode along the first direction; b represents the maximum distance between the electron and the closest point to the electrode along the second direction; and c represents the distance between the electron and the closest point to the electrode. 2 =a 2 +b 2 c 2 The maximum value is a 2 +b 2 The maximum value, that is, a 2 +b 2 The maximum value can characterize the square of the longest electron transport distance in the positive electrode.

[0596] In all embodiments and comparative examples, the electrode assembly is a stacked electrode assembly, and the tabs of the positive electrode and the negative electrode are configured in the same way.

[0597] "Positive electrode tab exiting on the short side" means that the positive electrode tab is located on at least one side of the positive current collector along the length direction of the positive current collector (the first direction, the length direction of the electrode body, the length direction of the positive current collector, and the length direction of the battery cell are all parallel); "Positive electrode tab exiting on one side of the short side" means that all positive electrode tabs are located on the same side of the positive current collector along the length direction; "Positive electrode tab exiting on both sides of the short side" means that multiple positive electrode tabs are located on both sides of the positive current collector along the length direction, and when there are two positive electrode tabs, one positive electrode tab is located on each side of the positive current collector.

[0598] "Positive electrode tab extending along the long side" means that the positive electrode tab is located on at least one side of the positive current collector along the width direction of the positive current collector (the first direction, the width direction of the electrode body, the width direction of the positive current collector, and the width direction of the battery cell are all parallel); "Positive electrode tab extending along the long side to one side" means that all positive electrode tabs are located on the same side of the positive current collector along the width direction.

[0599] A full electrode tab refers to a single positive electrode tab where the ratio of the dimension W11 of the positive electrode tab along the second direction to the dimension W2 of the electrode body along the second direction is 1.

[0600] In Comparative Example 1, the positive electrode active material layer is longer and has a higher energy density; however, the positive electrode tab is located on one side of the positive electrode current collector along the length direction, and 'a' is equal to the length of the positive electrode current collector, that is, 'a' is equal to the length of the positive electrode active material layer. Since the positive electrode tab is a full tab, its width is the same as the width of the positive electrode active material layer, therefore, 'b' is 0. This arrangement makes the electron transport path longer in the length direction, resulting in higher internal resistance of the battery cell, which is not conducive to fast charging at high energy density.

[0601] In Comparative Example 2, the length of the positive electrode active material layer is too long, although the energy density is high. However, the positive electrode tab is located on one side of the positive electrode current collector along the length direction, and 'a' is equal to the length of the positive electrode current collector, that is, 'a' is equal to the length of the positive electrode active material layer. Since the positive electrode tab is a full tab, its width is the same as the width of the positive electrode active material layer, therefore, 'b' is 0. This setting makes the electron transport path in the length direction longer, resulting in higher internal resistance of the battery cell, which is not conducive to fast charging at high energy density.

[0602] In Comparative Example 3, the positive electrode tab is located on one side of the positive electrode current collector along the width direction. 'a' is equal to the width of the positive electrode current collector, which is equal to the width of the positive electrode active material layer. Since the positive electrode tab is a full tab, its length is the same as the length of the positive electrode active material layer. Therefore, 'b' is 0. Although this arrangement makes the electron transport path shorter, the width of the positive electrode active material layer is small, and the length of the tab is large, which is not conducive to improving the energy density of the battery cell.

[0603] In Examples 6 to 9, the positive electrode tabs are located on both sides of the positive electrode current collector along the length direction, and a is equal to half of the positive electrode current collector. Since the positive electrode tabs are full tabs, their width is the same as the width of the positive electrode active material layer, therefore, b is 0. This arrangement ensures that the electron transport path in the length direction is not too long. The shorter electron transport path can reduce the internal resistance of the battery cell and is beneficial for fast charging under high energy density.

[0604] In Examples 1 to 5, the positive electrode tab is located on one side of the positive electrode current collector along the width direction. Because the width of the positive electrode active material layer is relatively short, the electron transport path in the width direction is shorter, effectively reducing the internal resistance of the battery cell and facilitating fast charging at high energy density. With a 2 +b 2 The decrease in the maximum value of a further shortens the electron transport path, which can more effectively reduce the internal resistance of the battery cell; however, as a 2 +b 2 A decrease in the maximum value may lead to a corresponding decrease in the energy density of individual battery cells, making it impossible to meet the demand for high energy density; therefore, in embodiment a of this application... 2 +b 2The maximum value is 6,000 to 110,000, which can effectively balance improving the energy density of individual battery cells and fast charging performance, and is conducive to achieving fast charging at high energy density.

[0605] As shown in Figure 12, in Example 1, there are two positive electrode tabs, which are located on the same side of the positive current collector along the width direction, and a is 100mm; the length dimension of each positive electrode tab is 125mm, W11 is 125mm, n is 2, W2 is 500mm, that is, n×W11 / W2 is 0.5; the distance D1 between two adjacent positive electrode tabs is 200mm, then b is half of the distance, which is 100mm.

[0606] As shown in Figure 7, in Example 2, there are four positive electrode tabs, which are located on the same side of the positive current collector along the width direction, where a is 100mm. The length dimension of each positive electrode tab is 100mm, W11 is 100mm, n is 4, and W2 is 500mm, i.e., n×W11 / W2 is 0.8. The distance D1 between two adjacent positive electrode tabs is 25mm, so b (b1 or b2 in Figure 7) is half of the distance D1 (corresponding to point A2), or it is the positive current collector minus the size occupied by the positive electrode tabs, and then minus the remaining size occupied by the distance (b3 corresponding to point A1 in Figure 7), both of which are 12.5mm.

[0607] As shown in Figure 11, in Example 3, there is one positive electrode tab, W11 is 500mm, n is 1, W2 is 500mm, that is, n×W11 / W2 is 1, a is 100mm, and b is 0.

[0608] As shown in Figure 12, in Example 4, there are two positive electrode tabs, which are located on the same side of the positive current collector along the width direction, and a is 100mm; the length dimension of each positive electrode tab is 162.5mm, W11 is 162.5mm, n is 2, W2 is 650mm, that is, n×W11 / W2 is 0.5; the distance D1 between two adjacent positive electrode tabs is 200mm, then b is half of the distance, which is 100mm.

[0609] As shown in Figure 12, in Example 5, there are two positive electrode tabs, which are located on the same side of the positive current collector along the width direction, and a is 80mm; the dimension of each positive electrode tab along the length direction is 80mm, W11 is 80mm, n is 2, W2 is 320mm, that is, n×W11 / W2 is 0.5; the distance D1 between two adjacent positive electrode tabs is 90mm, then b is half of the distance, which is 45mm.

[0610] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0611] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A battery cell, comprising a housing, an electrode assembly, and electrode terminals, wherein at least a portion of the electrode assembly is housed within the housing, and the electrode terminals are disposed on the housing; The electrode assembly includes a first electrode and a second electrode, wherein one of the first electrode and the second electrode is a positive electrode and the other is a negative electrode. Both the first electrode and the second electrode include an electrode body and at least one electrode tab. At least a portion of the electrode body is provided with an active material layer, and at least a portion of the electrode tab is not provided with the active material layer. The electrode body and the electrode tab are arranged along a first direction, and the dimension of the electrode tab along a second direction is less than or equal to the dimension of the electrode body along the second direction. The first direction, the second direction, and the thickness direction of the electrode body are perpendicular to each other. The tab portion is electrically connected to the electrode terminal; The first electrode satisfies: a 2 +b 2 The maximum value is between 6,000 and 110,000; among which, a represents the distance along the first direction between any point A of the electrode body and the electrode tab closest to point A in the at least one electrode tab, with the unit of a being mm; b represents the distance along the second direction between point A and the electrode tab closest to point A in the at least one electrode tab, with the unit of b being mm.

2. The battery cell according to claim 1, wherein, The dimension of the electrode body along the first direction is greater than the dimension of the electrode body along the second direction.

3. The battery cell according to claim 2, wherein, The first electrode has multiple tabs, which are respectively disposed on both sides of the electrode body along the first direction.

4. The battery cell according to claim 2 or 3, wherein, The electrode body has a dimension of 320 mm to 650 mm along the first direction.

5. The battery cell according to any one of claims 2-4, wherein, The first electrode satisfies: a 2 +b 2 The maximum value is between 25,600 and 110,000; optionally, a 2 +b 2 The maximum value is between 25,600 and 90,000.

6. The battery cell according to claim 1, wherein, The dimension of the electrode body along the first direction is smaller than the dimension of the electrode body along the second direction.

7. The battery cell according to claim 6, wherein, The first electrode has multiple tabs, and all of the tabs of the first electrode are located on the same side of the electrode body along the first direction.

8. The battery cell according to claim 6 or 7, wherein, The electrode body has a dimension of 50mm-200mm along the first direction, and optionally, the electrode body has a dimension of 80mm-150mm along the first direction.

9. The battery cell according to claims 6-8, wherein, The first electrode satisfies: a 2 +b 2 The maximum value is 6400 to 45000; optionally, a 2 +b 2 The maximum value is between 6400 and 25000.

10. The battery cell according to any one of claims 1-9, wherein, The first electrode has multiple tabs located on the same side of the electrode body, and the distance between two adjacent tabs along the second direction is greater than 0 and less than or equal to 300 mm.

11. The battery cell according to any one of claims 1-10, wherein, The sum of the dimensions of all the tabs located on the same side of the electrode body along the second direction is W1, and the dimension of the electrode body along the second direction is W2; The first electrode satisfies the following condition: W1 / W2 is between 0.5 and 1.

0.

12. The battery cell according to any one of claims 1-11, wherein, The electrode body includes a current collection section, and at least a portion of the active material layer is disposed on the surface of the current collection section; The current collection section includes a first current collection area and a second current collection area arranged along the second direction, and the electrode portion extends from the end of the second current collection area along the first direction; The dimension of the first current collection area along the second direction is L1, and the dimension of the second current collection area along the second direction is L2; 2≤L1 / L2≤30, optionally, 6≤L1 / L2≤20.

13. The battery cell according to any one of claims 1-12, wherein, The electrode body includes a current collection section, and at least a portion of the active material layer is disposed on the surface of the current collection section; The current collection section includes a first current collection area and a second current collection area arranged along the second direction, and the electrode portion extends from the end of the second current collection area along the first direction; The dimension of the first current collection area along the second direction is L1, and the dimension of the first current collection area along the first direction is L3; 0.1≤L3 / L1≤5, optionally, 0.5≤L3 / L1≤2.

14. The battery cell according to claim 12 or 13, wherein, The current collection section includes a plurality of first current collection areas and a plurality of second current collection areas, which are alternately arranged along the second direction; Each of the second current collection zones is connected to at least one of the said tabs.

15. The battery cell according to any one of claims 1-14, wherein, The electrode body of the first electrode includes a coating area and a transition area arranged along the first direction. The active material layer is disposed in the coating area, and neither the transition area nor the tab portion is provided with the active material layer. The transition area connects the coating area and the tab portion. The first electrode also includes an insulating element, at least a portion of which is disposed in the transition region.

16. The battery cell according to any one of claims 1-15, wherein, The second electrode satisfies: e 2 +f 2 The maximum value is 6000 to 110000; where e represents the distance along the first direction between any point B of the electrode body and the electrode ear closest to point B in the at least one electrode ear, and the unit of e is mm; f represents the distance along the second direction between point B and the electrode ear closest to point B in the at least one electrode ear, and the unit of f is mm.

17. The battery cell according to any one of claims 1-16, wherein, The active material layer of the positive electrode sheet comprises a lithium phosphate with an olivine structure; and / or, The active material layer of the negative electrode sheet comprises a carbon-based material.

18. The battery cell according to any one of claims 1-17, wherein, The negative electrode sheet includes a current collector and an active material layer. The current collector of the negative electrode sheet is a negative current collector, and the active material layer of the negative electrode sheet is a negative active material layer. The negative electrode active material layer includes a first negative electrode film layer and a second negative electrode film layer. The first negative electrode film layer is disposed on the surface of the negative electrode current collector, and the second negative electrode film layer is disposed on the side of the first negative electrode film layer opposite to the negative electrode current collector. The volume average particle size Dv50 of the carbon-based material in the first negative electrode film is greater than or equal to the volume average particle size Dv50 of the carbon-based material in the second negative electrode film.

19. The battery cell according to any one of claims 1-18, wherein, The electrode assembly includes multiple electrode tabs of the same polarity, and each electrode tab group includes at least two electrode tabs stacked together. The battery cell includes an adapter connected to the electrode terminals, and the adapter is connected to a plurality of the tabs.

20. The battery cell according to any one of claims 1-19, wherein, The battery cell is a square battery cell; In the length direction of the battery cell, the size of the electrode body is 320mm to 650mm, and the first direction is parallel to the length direction of the battery cell or parallel to the width direction of the battery cell.

21. The battery cell according to any one of claims 1-18, wherein, The battery cell is a cylindrical battery cell, and the first direction is parallel to the axial direction of the battery cell.

22. The battery cell according to claim 21, wherein, The outer casing includes a first end wall, a second end wall, and a side wall. The first end wall and the second end wall are disposed along the first direction, and the side wall connects the first end wall and the second end wall. The electrode terminal is insulated and disposed on the first end wall; One of the tab portion of the first electrode and the tab portion of the second electrode is electrically connected to the first end wall, and the other is electrically connected to the electrode terminal.

23. The battery cell according to claim 22, wherein, The sidewall is provided with an inwardly protruding protrusion, and the battery cell also includes an adapter, which is located on one side of the electrode assembly along the first direction and connected to the protrusion. One of the tabs of the first electrode and the tabs of the second electrode is disposed at one end of the electrode assembly facing the adapter and connected to the adapter.

24. A battery device comprising a plurality of battery cells according to any one of claims 1-23.

25. An electrical device comprising a battery device according to claim 24, the battery device being used to provide electrical energy.

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