Battery cell, battery device and electric device

Abstract

The invention relates to a battery monomer, a battery device and a power utilization device, the battery monomer comprises an electrode assembly and a shell assembly, the electrode assembly comprises a plurality of first pole pieces and second pole pieces, the first pole pieces and the second pole pieces comprise coating parts and tab parts, and the tab parts are connected to the coating parts and extend out of the coating parts; the shell assembly comprises a shell, at least one first electrode terminal and a second electrode terminal, the electrode assembly is accommodated in the shell, the first electrode terminal is connected with the tab part of the first pole piece, the second electrode terminal is connected with the tab part of the second pole piece, one of the first pole piece and the second pole piece is a positive pole piece, and the other one is a negative pole piece; the positive pole piece comprises lithium-containing phosphate with an olivine structure; the ratio of the size of the coating part of the positive pole piece along the length direction of the battery monomer to the size of the coating part of the positive pole piece along the width direction of the battery monomer is 4-7; and the battery monomer meets the condition that (x1 * S1 + x2 * S2) / E is 0.4-1.4.

Description

[0001] This application claims the priority of the international patent application PCT / CN2025 / 071057 titled "Battery Cell, Battery Device and Electric Appliance" filed on January 7, 2025, and the entire content of this application is incorporated herein by reference. Technical Field

[0002] This application relates to a battery cell, a battery device and an electric appliance. Background Art

[0003] Battery cells have characteristics such as high capacity and long life, and are thus widely used in electronic devices, such as mobile phones, laptop computers, battery-powered vehicles, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc. Due to the great progress of batteries, higher requirements are put forward for the performance of batteries. However, the fast charging ability and energy density of battery cells need to be further improved. Summary of the Invention

[0004] This application provides a battery cell, a battery device and an electric appliance, and the fast charging ability and energy density of the battery cell of this application can be further improved.

[0005] In a first aspect, an embodiment of this application provides a battery cell. The battery cell includes an electrode assembly and a housing assembly. The electrode assembly includes a plurality of first electrode plates and a plurality of second electrode plates. The first electrode plates and the second electrode plates are stacked along the thickness direction of the battery cell. Both the first electrode plates and the second electrode plates include a coating portion and a tab portion. The coating portion is provided with an active material layer, and the tab portion is connected to the coating portion and extends out of the coating portion; the housing assembly includes a housing and a terminal assembly provided on the housing. The housing houses the electrode assembly. The terminal assembly includes at least one first electrode terminal and at least one second electrode terminal. The first electrode terminal is connected to the tab portion of the first electrode plate, and the second electrode terminal is connected to the tab portion of the second electrode plate. Wherein, one of the first electrode plates and the second electrode plates is a positive electrode plate, and the other is a negative electrode plate. The active material layer of the positive electrode plate includes lithium-containing phosphate with an olivine structure; the size of the coating portion of the positive electrode plate along the length direction of the battery cell is a first size, and the size of the coating portion of the positive electrode plate along the width direction of the battery cell is a second size. The ratio of the first size to the second size is 4 to 7. The battery cell satisfies: (x 1 ×S 1 +x 2 ×S 2 ) / E is 0.4 to 1.4. x 1 represents the number of the first electrode terminals; x 2Represents the number of second electrode terminals; S 1 Represents the minimum cross-sectional area of a single first electrode terminal perpendicular to its own thickness direction, and its unit is mm 2 ; S 2 Represents the minimum cross-sectional area of a single second electrode terminal perpendicular to its own thickness direction, and its unit is mm 2 ; E represents the single-cell energy of the battery cell, and its unit is Wh.

[0006] Thus, in the embodiments of the present application, the ratio of the dimension of the coating portion of the positive electrode tab in the length direction to the dimension of the coating portion of the positive electrode tab in the width direction is 4 to 7. The length of the coating portion is relatively long, which is beneficial to carrying a relatively large amount of positive active material and is beneficial to making the battery cell have a relatively high energy density; when the length of the coating portion is relatively long, the electron transmission path in the length direction is relatively long, and the internal resistance is relatively high, which is not conducive to fast charging. Moreover, the positive active material includes lithium-containing phosphate with relatively poor conductivity, which further increases the internal resistance of the positive electrode tab; in order for the battery cell to quickly store a relatively large amount of single-cell energy, when (x 1 ×S 1 +x 2 ×S 2 ) / E is greater than or equal to 0.4, the overcurrent capacity of the first electrode terminal and the second electrode terminal is relatively strong, electrons can be quickly conducted, the internal resistance of the battery cell is effectively reduced, and the heat generation of the battery cell is reduced, thereby improving the fast charging ability of the battery cell and enabling the battery cell to reach the required capacity under fast charging.

[0007] In some embodiments, S 1 is 15 to 60; when the overcurrent area of the first electronic terminal is within the above range, its overcurrent capacity is relatively strong, and the fast charging ability of the battery cell can be improved.

[0008] In some embodiments, S 2 is 15 to 60. When the overcurrent area of the second electronic terminal is within the above range, its overcurrent capacity is relatively strong, and the fast charging ability of the battery cell can be improved.

[0009] In some embodiments, x 1 is 1 to 4; as the number of first electrode terminals increases, the overcurrent capacity of all first electrode terminals increases, and the fast charging ability of the battery cell can be improved.

[0010] In some embodiments, x 2 is 1 to 4. As the number of second electrode terminals increases, the overcurrent capacity of all second electrode terminals increases, and the fast charging ability of the battery cell can be improved.

[0011] In some embodiments, the battery cell further satisfies: M 1 / E is from 0.2 to 0.6; M 1 represents the area of the first connection region, and its unit is mm 2 ; the first connection region is the region where at least one first electrode terminal is connected to the tab of the first electrode plate.

[0012] Thus, when the battery cell in the embodiments of the present application satisfies the above conditions, the current conduction ability between the first electrode terminal and the tab of the first electrode plate is relatively strong, which is beneficial to reducing the internal resistance of the battery cell, reducing the heat generation of the battery cell, thereby improving the fast charging ability of the battery cell, and enabling the battery cell to reach the required capacity under fast charging.

[0013] In some embodiments, the battery cell further satisfies: M 2 / E is from 0.2 to 0.6; M 2 represents the area of the second connection region, and its unit is mm 2 ; the second connection region is the region where at least one second electrode terminal is connected to the tab of the second electrode plate.

[0014] Thus, when the battery cell in the embodiments of the present application satisfies the above conditions, the current conduction ability between the first electrode terminal and the tab of the first electrode plate is relatively strong, which is beneficial to reducing the internal resistance of the battery cell, reducing the heat generation of the battery cell, thereby improving the fast charging ability of the battery cell, and enabling the battery cell to reach the required capacity under fast charging.

[0015] In some embodiments, M 1 is from 60 to 120; the current conduction ability between the first electrode terminal and the first tab is relatively strong, which is beneficial to reducing the internal resistance of the battery cell, reducing the heat generation of the battery cell, thereby improving the fast charging ability of the battery cell.

[0016] In some embodiments, M 2 is from 60 to 120. The current conduction ability between the second electrode terminal and the second tab is relatively strong, which is beneficial to reducing the internal resistance of the battery cell, reducing the heat generation of the battery cell, thereby improving the fast charging ability of the battery cell.

[0017] In some embodiments, E is from 170 to 480. When the battery cell satisfies the above conditions, the energy density of the battery cell is relatively high.

[0018] In some embodiments, the first electrode terminal is disposed on at least one side of the electrode assembly in the length direction, which is beneficial to reducing the occupied space of the first electrode terminal and improving the energy density of the battery cell.

[0019] In some embodiments, the second electrode terminal is disposed on at least one side of the electrode assembly in the length direction, which is beneficial to reducing the occupied space of the second electrode terminal and improving the energy density of the battery cell.

[0020] In some embodiments, there are at least two first electrode terminals, and the at least two first electrode terminals are respectively disposed on both sides of the electrode assembly in the length direction; the transmission path of electrons in the length direction is shortened, which is beneficial to reducing the impedance and improving the fast charging ability of the battery cell.

[0021] In some embodiments, there are at least two second electrode terminals, and the at least two second electrode terminals are respectively disposed on both sides of the electrode assembly in the length direction. The transmission path of electrons in the length direction is shortened, which is beneficial to reducing the impedance and improving the fast charging ability of the battery cell.

[0022] In some embodiments, the housing includes a housing body and an end cap. The electrode assembly is accommodated in the housing body. The housing body includes an opening, and the end cap covers the opening. The first electrode terminal is disposed on the end cap.

[0023] In some embodiments, the first electrode terminal includes a first main body portion and a first protruding portion. The first main body portion is disposed on the housing and penetrates through the end cap of the housing; the first protruding portion is disposed on the first main body portion and protrudes from the first main body portion to be connected to the side of the end cap facing the electrode assembly. This setting method is beneficial to increasing the current-carrying capacity of the first electrode terminal.

[0024] In some embodiments, in the direction from the first main body portion to the first protruding portion, the size of the first protruding portion is 1.5 mm to 3.0 mm.

[0025] Thus, when the first protruding portion meets the above conditions, the connection area between the first protruding portion and the housing is relatively larger, the connection strength is higher, and the structure makes the structure of the battery cell more stable.

[0026] In some embodiments, the first main body portion and the first protruding portion are of an integral structure. This setting method is beneficial to increasing the current-carrying capacity of the first electrode terminal.

[0027] In some embodiments, the first main body portion is disposed on the end cap and penetrates through the end cap, and the ratio of the size of the first main body portion in the thickness direction of the battery cell to the size of the end cap in the thickness direction of the battery cell is 0.20 to 0.40.

[0028] Thus, when the first main body portion in the embodiments of the present application meets the above conditions, the size ratio of the first main body portion is relatively high, which is beneficial to improving the current-carrying capacity of the first electrode terminal and thus improving the fast charging performance.

[0029] In some embodiments, the housing assembly further includes a first conductive fixing member, at least a part of the first conductive fixing member is located on the side of the end cap facing away from the electrode assembly, the first conductive fixing member is disposed around the outside of the first main body portion, and is fixedly connected to the first main body portion and the end cap. The first conductive fixing member can increase the current-carrying capacity with an external busbar assembly and improve the fast charging performance.

[0030] In some embodiments, the ratio of the dimension of the first conductive fixing member in the thickness direction of the battery cell to the dimension of the end cap in the thickness direction of the battery cell is 0.40 to 0.80. The first conductive fixing member can increase the current-carrying capacity with an external busbar assembly and improve the fast charging performance.

[0031] In some embodiments, the tab portion of the first electrode tab is disposed on at least one side of the coating portion along the first direction, and the first electrode tab satisfies: n*W1 / W2 is 0.5 to 1.0; n represents the number of all tab portions on the same side of the coating portion; W1 represents the average dimension of the tab portion in the second direction, one of the first direction and the second direction is parallel to the length direction of the battery cell, and the other is parallel to the width direction of the battery cell; W2 represents the dimension of the coating portion in the second direction. The tab portion has a strong current-carrying capacity, which is beneficial to improving the current-carrying capacity of the battery device and improving the fast charging performance of the battery device.

[0032] In some embodiments, the first direction is parallel to the length direction of the battery cell.

[0033] In some embodiments, the first electrode tab includes a plurality of tab portions. The tab portion has a strong current-carrying capacity, which is beneficial to improving the current-carrying capacity of the battery device and improving the fast charging performance of the battery device.

[0034] In some embodiments, the number of tab portions of the first electrode tab on the same side of the coating portion is at least two. The above arrangement makes the electron transmission path shorter, which is beneficial to improving the fast charging ability.

[0035] In some embodiments, the plurality of tab portions of the first electrode tab are located on both sides of the coating portion along the first direction. The above arrangement makes the electron transmission path shorter, which is beneficial to improving the fast charging ability.

[0036] In some embodiments, all the tab portions of the first electrode tab are located on the same side of the coating portion along the first direction. The tab portion has a strong current-carrying capacity, which is beneficial to improving the current-carrying capacity of the battery device and improving the fast charging performance of the battery device.

[0037] In some embodiments, the ratio of the length of the battery cell to the thickness of the battery cell is 40 to 70.

[0038] In some embodiments, the ratio of the width of the battery cell to the thickness of the battery cell is 3 to 15.

[0039] In some embodiments, the thickness of the battery cell is 10 mm to 30 mm. When the thickness of the battery cell is within the above range, the thickness of the battery cell is relatively small, which is beneficial to the rapid heat dissipation inside the battery cell and reduces the risk of thermal runaway.

[0040] In some embodiments, the lithium-containing phosphate with olivine structure includes lithium iron phosphate. Lithium iron phosphate has relatively excellent cycle stability and can improve the cycle performance of the battery cell under fast charging.

[0041] In some embodiments, the active material layer of the positive electrode sheet is a positive electrode film layer, and the single-sided coating weight of the positive electrode film layer is 250 mg / 1540.25 mm 2 to 330 mg / 1540.25 mm 2 ; when the single-sided coating weight of the positive electrode film layer is within the above range, the heat generation per unit area of the positive electrode sheet will not be too large, and it can take into account the improvement of the energy density and charging rate performance of the battery cell.

[0042] In some embodiments, when the battery cell is in the 0% state of charge, the compaction density of the positive electrode film layer is 2.30 g / cm 3 to 2.70 g / cm 3 ; when the compaction density of the positive electrode film layer is within the above range, it is beneficial to improve the energy density of the battery cell; and because the positive electrode active materials in the positive electrode film layer are stacked relatively closely, the contact resistance between particles is small, which can further reduce the resistance of the electrode sheet, thereby reducing the heat generation during fast charging.

[0043] In some embodiments, the active material layer of the negative electrode sheet is a negative electrode film layer, and the single-sided coating weight of the negative electrode film layer is 120 mg / 1540.25 mm 2 to 180 mg / 1540.25 mm 2 ; when the single-sided coating weight of the negative electrode film layer is within the above range, the heat generation per unit area of the negative electrode sheet will not be too large, and it can take into account the improvement of the energy density of the battery cell.

[0044] In some embodiments, when the battery cell is in the 0% state of charge, the compaction density of the negative electrode film layer is 1.30 g / cm 3 to 1.65 g / cm 3 . When the compaction density of the negative electrode film layer is within the above range, it is beneficial to improve the energy density of the battery cell; and because the negative electrode active materials in the negative electrode film layer are stacked relatively closely, the contact resistance between particles is small, which can further reduce the resistance of the electrode sheet, thereby reducing the heat generation.

[0045] In some embodiments, the coating portion of the negative electrode plate includes a negative electrode current collector portion and a negative electrode film layer provided on at least one side of the negative electrode current collector portion. The negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material. Among them, the negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer. The first negative electrode film layer is provided on the surface of the negative electrode current collector portion; the second negative electrode film layer is connected to the side of the first negative electrode film layer facing away from the negative electrode current collector portion. Among them, the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is greater than or equal to the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer. In the embodiments of the present application, the particle size of the second negative electrode film layer is relatively small, which can shorten the solid-phase transmission path of lithium ions, improve the fast charging performance, and can improve the problem of lithium deposition on the surface layer of the negative electrode plate.

[0046] In some embodiments, the carbon-based material of the first negative electrode film layer is granular, and its volume average particle size Dv50 is 9.5 μm to 18.5 μm; when the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is within the above range, on the one hand, it can shorten the solid-phase transmission path of lithium ions and improve the fast charging performance. On the other hand, the material is not prone to agglomeration during the preparation process, which can improve the stability of the material.

[0047] In some embodiments, the carbon-based material of the second negative electrode film layer is granular, and its volume average particle size Dv50 is 7.8 μm to 14.3 μm. When the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer is within the above range, it can shorten the solid-phase transmission path of lithium ions and improve the fast charging performance.

[0048] In some embodiments, the carbon-based material of the first negative electrode film layer includes at least one of artificial graphite and natural graphite, and the carbon-based material of the second negative electrode film layer includes artificial graphite.

[0049] In some embodiments, the battery cell further includes an electrolyte, and the conductivity of the electrolyte at room temperature is 10 mS / cm to 13 mS / cm. The migration rate of lithium ions in this 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.

[0050] In some embodiments, the electrolyte includes an organic solvent, and the organic solvent includes a chain carboxylic ester solvent. The chain carboxylic ester solvent improves the conductivity of the electrolyte at room temperature and is beneficial to the migration of lithium ions.

[0051] In some embodiments, based on the mass of the electrolyte, the mass content of the chain carboxylic ester solvent is 5% to 30%, which makes the conductivity of the electrolyte relatively high and is beneficial to the migration of lithium ions.

[0052] In some embodiments, the electrolyte includes a lithium salt, and the lithium salt includes lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide. Based on the mass of the electrolyte, the ratio of the mass content of lithium hexafluorophosphate to the mass content of lithium bis(fluorosulfonyl)imide is 0.5 to 4. When the lithium salt meets the above conditions, the system is relatively stable and not easily decomposed. The lithium salt is beneficial to improving the conductivity of the electrolyte and enhancing the kinetic performance of the battery cell.

[0053] In some embodiments, the mass content of lithium bis(fluorosulfonyl)imide in the electrolyte is 1% to 15%. When the lithium salt meets the above conditions, the system is relatively stable and not easily decomposed. The lithium salt is beneficial to improving the conductivity of the electrolyte and enhancing the kinetic performance of the battery cell.

[0054] In a second aspect, embodiments of the present application further provide a battery device, including the battery cell of any one of the embodiments in the first aspect of the present application.

[0055] In a third aspect, embodiments of the present application further provide an electrical device, and the electrical device includes the battery device of any one of the embodiments in the second or third aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments of the present application. Obviously, the following described drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to the drawings without creative efforts.

[0057] Figure 1 is a schematic structural diagram of an electrical device provided by some embodiments of the present application; Figure 2 is a schematic structural diagram of a battery pack provided by some embodiments of the present application; Figure 3 is a schematic structural diagram of a battery module provided by some embodiments of the present application; Figure 4 is a schematic structural diagram of a battery cell provided by some embodiments of the present application; Figure 5 is a schematic structural diagram of an electrode assembly of a battery cell provided by some embodiments of the present application; Figure 6 is a schematic structural diagram of an end cap, a terminal assembly, and a first conductive fixing member of a battery cell provided by some embodiments of the present application; Figure 7 is Figure 6 a top view schematic diagram of; Figure 8 is Figure 7 a cross-sectional view taken along line A-A; Figure 9 It is a schematic structural diagram of a battery cell provided by some other embodiments of the present application; Figure 10 It is a schematic structural diagram of a battery cell provided by some other embodiments of the present application; Figure 11 It is a schematic structural diagram of a battery cell provided by some other embodiments of the present application; Figure 12 It is a schematic structural diagram of a battery cell provided by some other embodiments of the present application; Figure 13 It is a schematic structural diagram of a battery cell provided by some other embodiments of the present application; Figure 14 It is a schematic diagram of the first electrode tab of a battery cell provided by some embodiments of the present application; Figure 15 It is a schematic diagram of the first electrode tab of a battery cell provided by some other embodiments of the present application; Figure 16 It is a schematic diagram of the first electrode tab of a battery cell provided by some other embodiments of the present application; Figure 17 It is a schematic diagram of the first electrode tab of a battery cell provided by some other embodiments of the present application; Figure 18 It is a schematic diagram of the first electrode tab of a battery cell provided by some other embodiments of the present application.

[0058] The drawings are not necessarily drawn to actual scale.

[0059] The descriptions of the reference numerals are as follows: X, thickness direction; Y, width direction; Z, length direction; 1, electrical device; 2, battery pack; 3, controller; 4, motor; 5, box body; 5a, first box body part; 5b, second box body part; 5c, accommodation space; 6, battery module; 7, battery cell; 10, electrode assembly; 11, first electrode tab; 111, first tab ear; 1111, first end; 112, first coating part; 12, second electrode tab; 121, second tab ear; 122, second coating part; 13, separator; 20, housing assembly; 21, housing; 211, first housing part; 212, second housing part; 2121, first wall; 2122, second wall; 213, third housing part; 22, end cap; 31, first electrode terminal; 311, first protrusion; 312, first main body part; 32. Second electrode terminal; 41. First conductive fixing member; 51. First adapter; 511. First adapter portion; 512. Second adapter portion; 61. First conductive member; 611. First conductive portion; 612. Second conductive portion; 81. First heat conduction member. Detailed implementation manners

[0060] Hereinafter, embodiments of the battery cell, battery device, and electrical device of the present application that are specifically disclosed will be described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually identical structures are omitted. This is to prevent the following descriptions from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the accompanying drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0061] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, 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, ranges of 60 to 110 and 80 to 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" have been fully listed herein, and "0 to 5" is only an abbreviated representation of these numerical combinations. In addition, when it is stated that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0062] If there is no special instruction, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0063] If there is no special instruction, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0064] Unless otherwise specified, all steps of the present application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b) and (c), or can also include steps (a), (c) and (b), or can also include steps (c), (a) and (b), etc.

[0065] The term "a plurality of" as used in the present application refers to two or more (including two).

[0066] The battery cell includes an electrode assembly and electrode terminals. In the case of relatively high energy density, the over-current capacity during the charging process is poor, which increases the internal resistance of the battery cell and the heat generation, and is not conducive to the rapid charging of the battery cell.

[0067] In view of the above problems, the embodiments of the present application adopt a positive electrode plate with a specific size, so that the positive electrode plate can carry more active materials, improving the energy density of the battery cell; on the basis of high energy density, it is beneficial for the battery cell to store relatively more monomer energy; however, the above positive electrode plate is a long and narrow electrode plate, and the electron transmission path in the length direction is long, which is likely to increase the internal resistance; in order for the battery cell to quickly store more monomer energy, the embodiments of the present application also improve the over-current capacity of all electrode terminals, and the total over-current capacity of all electrode terminals is relatively excellent, which can reduce the internal resistance of the battery cell, enabling electrons to migrate quickly, and is beneficial for rapid charging and storage capacity.

[0068] The battery cell of the present application is applicable to various battery devices and electrical devices that use battery cells.

[0069] Exemplarily, the electrical device can be a mobile phone, a portable device, a laptop computer, an electric vehicle, an electric toy, an electric tool, a vehicle, a ship, a spacecraft, etc. Or, exemplarily, the electrical device is a spacecraft, and the spacecraft includes an airplane, a rocket, a space shuttle, a spaceship, etc.

[0070] Figure 1 It is a schematic structural diagram of an electrical device provided by some embodiments of the present application. The electrical device 1 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirements of the electrical device 1 for high power and high energy density, a battery pack or a battery module can be adopted.

[0071] Inside the electrical device 1, a battery device is provided, and the battery device can be arranged at the bottom, head, or tail of the electrical device 1. The battery device can be used to supply power to the electrical device 1. For example, the battery device can serve as the operating power source of the electrical device 1 and also as the driving power source of the electrical device 1, replacing or partially replacing fuel or natural gas to provide driving power for the electrical device 1. Figure 1 The battery device shown in

[0072] The electrical device 1 may further include a controller 3 and a motor 4. The controller 3 is used to control the battery device to supply power to the motor 4. For example, it is used for the working power requirements during the startup, navigation, and driving of the electrical device 1.

[0073] The battery apparatus may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include a plurality of battery cells, and the plurality of battery cells are connected in series, parallel, or in a hybrid connection through a busbar component.

[0074] In some embodiments, the battery cell assembly is generally formed by arranging a plurality of battery cells.

[0075] As an example, the battery cell assembly can be a battery module, and the battery module is formed by arranging and fixing a plurality of battery cells into an independent module. As an example, the battery module can be formed by bundling a plurality of battery cells with cable ties.

[0076] As shown in Figure 2 In some embodiments, the battery device can be a battery pack 2, and the battery pack 2 includes a box body 5 and one or more battery cell assemblies, and the battery cell assemblies are accommodated in the box body 5.

[0077] As an example, the battery cell assembly can also be accommodated in the box body 5 by directly fixing a plurality of battery cells to the box body 5.

[0078] As an example, the box body 5 includes a first box body part 5a and a second box body part 5b. The box body 5 has an accommodation space 5c. The first box body part 5a and the second box body part 5b are snapped together so that a closed space is formed inside the box body 5 to accommodate the battery cell assembly. Here, "closed" means covered or closed, which can be sealed or non-sealed. The first box body part 5a can be a top cover or a bottom plate.

[0079] As an example, the box body 5 may include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame so that a closed space is formed inside the box body 5 to accommodate the battery cell assembly.

[0080] In some embodiments, the box body 5 can be part of the chassis structure of a vehicle. For example, a part of the box body 5 can form at least a part of the floor of the vehicle, or a part of the box body 5 can form at least a part of the cross beams and longitudinal beams of the vehicle.

[0081] As an example, the battery cell assembly can be a battery module 6, and the battery cell assembly can be accommodated in the box body 5 by fixing the battery module 6 in the box body 5.

[0082] As Figure 3 shown, the battery module 6 includes a plurality of battery cells 7.

[0083] In some embodiments, during the process of the battery device from 0% state of charge to 100% state of charge, the temperature of the external environment where the battery device is located is room temperature, such as 25°C.

[0084] In some embodiments, during the charging process of the battery device from 0% state of charge SOC to 100% state of charge SOC, the temperature of the external environment where the battery device is located is room temperature, such as 25°C.

[0085] In some embodiments, during the charging process of the battery device or any battery cell 7 constituting the battery device from 10% SOC to 80% state of charge SOC, the temperature of the external environment where the battery device is located is room temperature, such as 25°C.

[0086] Exemplarily, the charging steps of the battery device or any battery cell 7 constituting the battery device from 10% SOC to 80% SOC can be carried out in the following manner: Charge from 10% SOC to 25% SOC at a constant current of 7.0C; Charge from 25% SOC to 30% SOC at a constant current of 7.0C; Charge from 30% SOC to 35% SOC at a constant current of 7.0C; Charge from 35% SOC to 40% SOC at a constant current of 7.0C; Charge from 40% SOC to 45% SOC at a constant current of 6.7C; Charge from 45% SOC to 50% SOC at a constant current of 6.5C; Charge from 50% SOC to 55% SOC at a constant current of 6.0C; Charge from 55% SOC to 60% SOC at a constant current of 5.8C; Charge from 60% SOC to 65% SOC at a constant current of 5.5C; Charge from 65% SOC to 70% SOC at a constant current of 5.2C; Charge from 70% SOC to 75% SOC at a constant current of 5.0C; Charge from 75% SOC to 80% SOC at a constant current of 4.8 C.

[0087] In some embodiments, the charging time of the battery device or any battery cell 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 temperature of the external environment of the battery device at 10% state of charge is room temperature, such as 25 °C. Exemplarily, the charging time of 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 the range composed of any two of the above values.

[0088] As Figures 4 to 8 shown, the battery cell 7 includes an electrode assembly 10 and a housing assembly 20. The electrode assembly 10 includes a plurality of first electrode plates 11 and a plurality of second electrode plates 12. The first electrode plates 11 and the second electrode plates 12 are stacked along the thickness direction X of the battery cell 7. Both the first electrode plates 11 and the second electrode plates 12 include a coated portion and an electrode tab portion. The coated portion is provided with an active material layer. The electrode tab portion is connected to the coated portion and extends out of the coated portion, and no active material layer is coated thereon; one of the first electrode plates 11 and the second electrode plates 12 is a positive electrode plate, and the other is a negative electrode plate. The active material layer of the positive electrode plate includes a positive electrode active material, and the positive electrode active material includes a lithium phosphate with an olivine structure; The size of the coated portion of the positive electrode plate along the length direction Z is a first size, and the size of the coated portion of the positive electrode plate along the width direction Y is a second size. The ratio of the first size to the second size is 4 to 7; The housing assembly 20 includes a housing and a terminal assembly. The housing houses the electrode assembly 10. The terminal assembly includes at least one first electrode terminal 31, and the first electrode terminal 31 is connected to the electrode tab portion of the first electrode plate 11. The terminal assembly further includes at least one second electrode terminal 32, and the second electrode terminal 32 is connected to the electrode tab portion of the second electrode plate 12; Among them, the battery cell satisfies: (x 1 ×S 1 +x 2 ×S 2 ) / E is 0.4 to 1.4, x 1 represents the number of the first electrode terminals 31; x2 represents the number of the second electrode terminals 32; S 1 represents the minimum cross-sectional area of a single first electrode terminal 31 perpendicular to its own thickness direction, with the unit of mm 2 ; S 2 represents the minimum cross-sectional area of a single second electrode terminal 32 perpendicular to its own thickness direction, with the unit of mm 2 ; E represents the single-cell energy of the battery cell, with the unit of Wh.

[0089] Optionally, the electrode assembly 10 further includes a separator 13, and the separator 13 is located between the first electrode sheet 11 and the second electrode sheet 12.

[0090] The electrode assembly 10 has a stacked structure, and a plurality of first electrode sheets 11 and a plurality of second electrode sheets 12 are stacked. Compared with the wound structure, the stacked structure has no bending area, and it is easier to increase the coating amount of the active material on the stacked structure, so that the battery cell 7 has a relatively high energy density; and in the embodiment of the present application, the ratio of the size of the coating portion of the positive electrode sheet along the length direction Z to the size of the coating portion of the positive electrode sheet along the width direction Y is 4 to 7, and the length of the coating portion is relatively long, which is beneficial to carrying a relatively large amount of positive electrode active material, is beneficial to making the battery cell 7 have a relatively high energy density, and is beneficial to the battery cell 7 storing more single-cell energy; When the length of the coating portion is relatively long, the electron transmission path in the length direction is long, and the internal resistance is relatively high, which is not conducive to rapid charging. Moreover, the positive electrode active material includes lithium-containing phosphate with relatively poor conductivity, which further increases the internal resistance of the positive electrode sheet; In order for the battery cell to quickly store a relatively high single-cell energy, the embodiment of the present application also improves the total over-current capacity of all the electrode terminals, x 1 ×S 1 +x 2 ×S 2 can characterize the total over-current capacity of all the electrode terminals in the battery cell 7. When (x 1 ×S 1 +x 2 ×S 2 ) / E is greater than or equal to 0.4, the over-current areas of the first electrode terminal 31 and the second electrode terminal 32 are relatively high, the over-current capacity is relatively strong, electrons can be quickly conducted, and the internal resistance of the battery cell 7 can be effectively reduced, and the heat generation of the battery cell 7 can be reduced, thereby improving the rapid charging ability of the battery cell 7 and enabling the battery cell to quickly reach the required capacity.

[0091] Exemplarily, the formula (x 1 ×S1 +x 2 ×S 2 ) / E only performs numerical calculations without substituting units, (x 1 ×S 1 +x 2 ×S 2 ) / E can be 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 or a range composed of any two of the above numerical values.

[0092] In the embodiments of the present application, the dimension of the battery cell 7 in its own length direction is the length of the battery cell 7, the dimension of the battery cell 7 in its own width direction is the width of the battery cell 7, and the dimension of the battery cell 7 in its own thickness direction is the thickness of the battery cell 7. Figure 4 The X direction shown in is the thickness direction of the battery cell 7, the Y direction is the width direction of the battery cell 7, and the Z direction is the length direction of the battery cell 7.

[0093] In some embodiments, the ratio of the length of the battery cell 7 to the thickness of the battery cell 7 is 40 to 70, such as 40, 45, 50, 55, 60, 65, 70 or a range composed of any two of the above numerical values. When the ratio of the length of the battery cell 7 to the thickness of the battery cell 7 is within the above range, the energy density and fast charging performance of the battery cell can be balanced.

[0094] In some embodiments, the ratio of the width of the battery cell 7 to the thickness of the battery cell 7 is 3 to 15, such as 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15 or a range composed of any two of the above numerical values. Optionally, the ratio of the width of the battery cell 7 to the thickness of the battery cell 7 is 4 to 12. When the ratio of the width of the battery cell 7 to the thickness of the battery cell 7 is within the above range, the energy density and fast charging performance of the battery cell can be balanced.

[0095] In some embodiments, the thickness of the battery cell 7 is 10 mm to 30 mm, such as 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm, 22 mm, 24 mm, 26 mm, 28 mm, 30 mm or a range composed of any two of the above numerical values. The relatively thin thickness of the battery cell 7 is beneficial to rapid heat dissipation, resulting in less heat accumulation in the system, which is beneficial to the fast charging of the battery cell 7.

[0096] In the embodiments of the present application, the single-cell energy of the battery cell 7 can characterize the electrical energy stored in the battery cell 7. E = U×Q, where U represents the rated voltage of the battery cell 7, with the unit of V; Q represents the rated capacity of the battery cell 7, with the unit of Ah.

[0097] The single-cell energy of the battery cell 7 can be adjusted by the size of the battery cell, the size of the positive and negative electrode plates, the material of the positive and negative active materials, the single-sided coating weight of the positive and negative electrode films, the compaction density, etc.

[0098] For example, as the length of the battery cell 7 increases, the loading capacity of the active material that can be accommodated increases, the rated capacity of the battery cell 7 increases, and the single-cell energy of the battery cell 7 can be improved; For example, as the thickness of the battery cell 7 increases, the loading capacity of the active material that can be accommodated increases, the rated capacity of the battery cell 7 increases, and the single-cell energy of the battery cell 7 can be improved; For example, as the length of the positive electrode film layer of the positive electrode plate increases, the loading capacity of the positive active material that can be accommodated increases, the rated capacity of the battery cell 7 increases, and the single-cell energy of the battery cell 7 can be improved; For example, as the single-sided coating weight of the positive electrode plate increases, the rated capacity of the battery cell 7 increases, and the single-cell energy of the battery cell 7 can be improved; For example, as the compaction density of the positive electrode plate increases, the rated capacity of the battery cell 7 increases, and the single-cell energy of the battery cell 7 can be improved; For example, if the positive active material is adjusted and the rated voltage is adjusted from 3.65V to 3.8V, the single-cell energy of the battery cell 7 increases.

[0099] Similarly, the change trend of the single-cell energy caused by the change of the relevant parameters of the negative electrode plate is the same as that caused by the positive electrode plate, which will not be elaborated here.

[0100] In some embodiments, the single-cell energy E Wh of the battery cell 7 is from 170Wh to 480Wh, such as 150Wh, 200Wh, 250Wh, 300Wh, 350Wh, 400Wh, 450Wh, 480Wh or the range composed of any two of the above values.

[0101] For example, when the battery cell 7 uses lithium-containing phosphate as the positive active material, its rated voltage is 3.22V; when the rated capacity is 100Ah, the single-cell energy of the battery cell 7 is 3.22V × 100Ah = 322Wh.

[0102] To more clearly illustrate the present application, the tab portion of the first electrode sheet 11 is defined as the first tab 111, and the coated portion of the first electrode sheet 11 is defined as the first coated portion 112. The tab portion of the second electrode sheet 12 is defined as the second tab 121, and the coated portion of the second electrode sheet 12 is defined as the second coated portion 122. The electrode terminal that is electrically connected and has the same electrical property as the first tab 111 is the first electrode terminal 31, and the electrode terminal that is electrically connected and has the same electrical property as the second tab 121 is the second electrode terminal 32.

[0103] The polarities of the first electrode sheet 11 and the second electrode sheet 12 are opposite. When the first electrode sheet 11 is the positive electrode sheet, the second electrode sheet 12 is the negative electrode sheet, the first electrode terminal 31 is the positive terminal, and the second electrode terminal 32 is the negative terminal; or when the first electrode sheet 11 is the negative electrode sheet, the second electrode sheet 12 is the positive electrode sheet, the first electrode terminal 31 is the negative terminal, and the second electrode terminal 32 is the positive terminal.

[0104] In an embodiment of the present application, optionally, the housing assembly 20 further includes a first conductive fixing member 41. The first conductive fixing member 41 is disposed around the first electrode terminal 31. The outer contour of the first electrode terminal 31 can be circular, oval, racetrack-shaped, rectangular, etc., and the first conductive fixing member 41 is disposed around the outer contour of the first electrode terminal 31.

[0105] [Housing Assembly] In some embodiments, the battery cell 7 further includes a housing assembly 20. The housing assembly 20 has a receiving space for receiving the electrode assembly 10 and the electrolyte. The housing assembly 20 includes a housing and a terminal assembly. The terminal assembly is disposed on the housing.

[0106] The housing can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), or an aluminum plastic film, etc. In some embodiments, the housing can be a sealed structure or a non-sealed structure. As an example, when the housing is a non-sealed structure, the housing serves to protect the electrode assembly 10, and a sealing bag is further included between the housing 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 member or an aluminum plastic film. When the housing is a sealed structure, it is used to encapsulate components such as the electrode assembly 10 and the electrolyte.

[0107] As an example, the battery cell 7 can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell, or a battery cell of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, a multi-prismatic battery, and the multi-prismatic battery is, for example, a hexagonal-prismatic battery, etc. There is no particular limitation in the present application.

[0108] In some embodiments, the outer shell includes an end cap 22 and a housing 21. The housing 21 is provided with an opening, and the end cap 22 covers the opening. The housing 21 may be provided with one or more openings. The end cap 22 may also be provided in one or more numbers.

[0109] The terminal assembly may be disposed in the housing 21, or the terminal assembly is disposed on the end cap 22. Optionally, the terminal assembly is disposed on the end cap 22. When the terminal assembly is disposed on the end cap 22, the thickness direction of the terminal assembly itself is perpendicular to the thickness direction X of the battery cell 7. Figure 8 The Z direction shown in the figure is parallel to the thickness direction of the first electrode terminal 31.

[0110] The first electrode terminal 31 and the second electrode terminal 32 may be disposed in the housing 21, or the first electrode terminal 31 and the second electrode terminal 32 are disposed on the end cap 22. Optionally, the first electrode terminal 31 and the second electrode terminal 32 are disposed on the end cap 22.

[0111] On the same end cap 22, the first electrode terminal 31 and the second electrode terminal 32 may be provided simultaneously. For example, there is one end cap 22, and the first electrode terminal 31 and the second electrode terminal 32 are spaced apart on the end cap 22. Another example is that there are two end caps 22, the two end caps 22 are disposed opposite to each other, and the first electrode terminal 31 and the second electrode terminal 32 are provided on each end cap 22.

[0112] The first electrode terminal 31 and the second electrode terminal 32 are respectively provided on different end caps 22. For example, there are two end caps 22, the two end caps 22 are disposed opposite to each other, the first electrode terminal 31 is provided on one of the end caps 22, and the second electrode terminal 32 is provided on the other end cap 22.

[0113] 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, the housing 21 of a cylindrical structure can be selected; if the electrode assembly 10 is a cuboid structure, the housing 21 of a cuboid structure can be selected. Optionally, both the electrode assembly 10 and the housing 21 are of cuboid structure.

[0114] In some embodiments, the battery cell 7 satisfies: x 1 ×S 1 / E is 0.2 to 0.7, S 1 represents the minimum cross-sectional area of a single first electrode terminal 31 perpendicular to its own thickness direction, and its unit is mm 2 .

[0115] x 1 ×S 1 represents the minimum cross-sectional area of all the first electrode terminals 31 perpendicular to their own thickness directions, and its unit is mm 2 .​

[0116] Exemplarily, x 1 ×S 1 / E. This formula only performs numerical calculations without substituting units. x 1 ×S 1 / E is 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7 or a range composed of any two of the above values.

[0117] x 1 ×S 1 / E is greater than or equal to 0.2. The overcurrent capacity of the first electrode terminal is relatively strong, and it can also effectively reduce the internal resistance of the battery cell 7, reduce the heat generation of the battery cell 7, improve the fast charging ability of the battery cell 7, and enable the battery cell 7 to quickly reach the required capacity.

[0118] In some embodiments, S 1 mm 2 is 15 mm 2 to 60 mm 2 ; for example, 15 mm², 30 mm², 35 mm², 40 mm², 45 mm², 50 mm², 55 mm², 60 mm² or a range composed of any two of the above values. When the overcurrent area of the first electrode terminal 31 is within the above range, its overcurrent capacity is relatively strong, and it can improve the fast charging ability of the battery cell.

[0119] In some embodiments, x 1 is 1 to 4, for example, 1, 2, 3, or 4. As the number of the first electrode terminals 31 increases, the overcurrent capacity of all the first electrode terminals 31 is enhanced, and it can improve the fast charging ability of the battery cell.

[0120] The part of the first electrode terminal 31 connected to the first conductive fixing member 41 is a solid structure with a preset height. Along the thickness direction of the first electrode terminal 31, the cross-sectional size of the first electrode terminal 31 perpendicular to its own thickness direction can be the same or different; when the cross-sectional size of the first electrode terminal 31 perpendicular to its own thickness direction is different, the one with the smallest area is defined as the minimum cross-sectional area. Figure 8 J shown in 1 is the cross-section where the minimum cross-sectional area is located, and its area is S 1 .

[0121] The outer contour of the minimum cross-sectional area is the minimum contour of the connection between the first electrode terminal 31 and the first conductive fixing member 41, and it is the bottleneck for current transmission between the first electrode terminal 31 and the first conductive fixing member 41; and in the embodiments of the present application, x 1 ×S 1 / E ranges from 0.2 to 0.7, such that the overcurrent capacity of the first electrode terminal 31 is relatively strong, which can effectively reduce the internal resistance of the battery cell 7, reduce the heat generation of the battery cell 7, and moreover, the thickness of the battery cell 7 is relatively thin, which is conducive to the rapid heat dissipation of the battery cell 7, thereby enhancing the rapid charging capacity of the battery cell 7.

[0122] In some embodiments, the first electrode terminal 31 is at least one, and may be at least two. For example, x 1 represents any positive integer from 1 to 4. x 1 ×S 1 can characterize the overcurrent capacity of all the first electrode terminals 31 in the battery cell 7.

[0123] In some embodiments, the first electrode terminal 31 may include a first main body portion 312 and a first protruding portion 311. The first main body portion 312 is disposed on the end cap 22 and penetrates through the end cap 22. The first protruding portion 311 is disposed on the first main body portion 312 and protrudes from the first main body portion 312 to be connected to the side of the end cap 22 facing the electrode assembly 10. It can be understood that the first protruding portion 311 is disposed around the outside of the first main body portion 312 and is connected to the side of the end cap 22 facing the electrode assembly 10. Optionally, the first conductive fixing member 41 is disposed around the outside of the first main body portion 312.

[0124] In some other embodiments, the first electrode terminal 31 may only include the first main body portion 312. The first main body portion 312 penetrates through the end cap 22 and is connected to the tab. Optionally, the first conductive fixing member 41 is disposed around the outside of the first main body portion 312.

[0125] In the embodiments of the present application, the first electrode terminal 31 may be an integral structure, which may be integrally formed or may be formed into an integral structure by means such as welding. The integral structure is conducive to reducing the resistance and reducing the heat generation.

[0126] Optionally, in the direction from the first main body portion 312 to the first protruding portion 311, the size of the first protruding portion 311 is 1.5 mm to 3.0 mm. When the first electrode terminal 31 is disposed on the end cap 22 of the housing, the direction from the first main body portion 312 to the first protruding portion 311 may be parallel to the width direction Y of the battery cell 7. In this case, the size of the first protruding portion 311 along the width direction Y is 1.5 mm to 3.0 mm. Figure 8 The T shown in 1 represents the size of the first protruding portion 311 along the width direction Y.

[0127] When the first protruding portion 311 satisfies the above conditions, the connection area between the first protruding portion 311 and the housing is relatively larger, the connection strength is higher, and the structure makes the structure of the battery cell 7 more stable.

[0128] Optionally, the ratio of the dimension of the first main body portion 312 in the thickness direction X of the battery cell 7 to the dimension of the end cap 22 in the thickness direction X of the battery cell 7 is 0.20 to 0.40, such as 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16, 0.18, 0.20, 0.22, 0.24, 0.26, 0.28, 0.30, 0.32, 0.34, 0.36, 0.38, 0.40 or the range composed of any two of the above values; the dimension of the first main body portion 312 refers to the dimension of the first main body portion 312 of a single first electrode terminal 31. Figure 7 X shown in 3 represents the dimension of the first main body portion 312 of a single first electrode terminal 31 in the thickness direction X, which can be understood as the width of the first main body portion 312; X 2 represents the dimension of the end cap 22 in the thickness direction X, which can be understood as the width of the end cap 22.

[0129] When the first main body portion 312 satisfies the above conditions, the dimension ratio of the first main body portion 312 is relatively high, which is beneficial to improving the over-current capacity of the first electrode terminal 31, thereby improving the fast charging performance.

[0130] The housing assembly 20 further includes a first conductive fixing member 41. At least a part of the first conductive fixing member 41 is located on the side of the end cap 22 facing away from the electrode assembly, and is used for connecting with an external busbar assembly. The first conductive fixing member 41 is disposed around the first electrode terminal 31 and fixedly connects the first electrode terminal 31 and the end cap 22.

[0131] The first conductive fixing member 41 can further increase the over-current area between the battery cell 7 and the external busbar assembly, thereby improving the over-current capacity, which is beneficial to improving the over-current capacity of the battery device and improving the fast charging performance of the battery device.

[0132] Optionally, a part of the first main body portion 312 protrudes from the side of the end cap 22 facing away from the electrode assembly 10, and the first conductive fixing member 41 is disposed around the first main body portion 312.

[0133] Optionally, the ratio of the dimension of the first conductive fixing member 41 in the thickness direction X of the battery cell 7 to the dimension of the end cap 22 in the thickness direction X of the battery cell 7 is 0.40 to 0.80, such as 0.40, 0.42, 0.44, 0.46, 0.48, 0.50, 0.52, 0.54, 0.56, 0.58, 0.60, 0.62, 0.64, 0.66, 0.68, 0.70, 0.72, 0.74, 0.76, 0.78, 0.80 or the range composed of any two of the above values. The dimension of the first conductive fixing member 41 refers to the dimension of a single first conductive fixing member 41. Figure 7X shown in 1 represents the dimension of the first conductive fixing member 41 in the thickness direction X, which can be understood as the width of the first conductive fixing member 41.

[0134] When the first conductive fixing member 41 meets the above conditions, the size ratio of the first conductive fixing member 41 is relatively high, which is beneficial to increasing the current-carrying area between the battery cell 7 and the external busbar assembly, thereby improving the current-carrying capacity and being beneficial to improving the current-carrying capacity of the battery device and the fast charging performance of the battery device.

[0135] As Figure 9 shown, in some embodiments, the terminal assembly further includes at least one second electrode terminal 32, and the second electrode terminal 32 is connected to the tab portion of the second electrode plate. The battery cell 7 satisfies: x 2 ×S 2 / E is 0.2 to 0.7. S 2 represents the minimum cross-sectional area of a single second electrode terminal 32 perpendicular to its own thickness direction, and its unit is mm 2 .

[0136] x 2 ×S 2 represents the minimum cross-sectional area of all second electrode terminals 32 perpendicular to their own thickness directions, and its unit is mm 2 .

[0137] In the embodiments of the present application, x 2 ×S 2 / E is 0.2 to 0.7, so that the current-carrying capacity of the second electrode terminal 32 is relatively strong, which can effectively reduce the internal resistance of the battery cell 7, reduce the heat generation of the battery cell 7, and improve the fast charging ability of the battery cell 7.

[0138] In some embodiments, S 2 mm 2 is 15 mm 2 to 60 mm 2 ; for example, 15 mm², 30 mm², 35 mm², 40 mm², 45 mm², 50 mm², 55 mm², 60 mm² or the range composed of any two of the above values. When the current-carrying area of the second electrode terminal 32 is within the above range, its current-carrying capacity is strong, which can improve the fast charging ability of the battery cell.

[0139] In some embodiments, x 2 is 1 to 4, such as 1, 2, 3 or 4. As the number of second electrode terminals 32 increases, the current-carrying capacity of all second electrode terminals 32 increases, which can improve the fast charging ability of the battery cell.

[0140] The portion of the second electrode terminal 32 connected to the second conductive fixing member is a solid structure with a preset height. Along the thickness direction of the second electrode terminal 32, the cross-sectional size of the second electrode terminal 32 perpendicular to its own thickness direction can be the same or different; when the cross-sectional size of the second electrode terminal 32 perpendicular to its own thickness direction is different, the one with the smallest area is defined as the minimum cross-sectional area.

[0141] The outer contour of the minimum cross-sectional area is the minimum contour of the connection between the second electrode terminal 32 and the second conductive fixing member, and it is the bottleneck for current transmission between the second electrode terminal 32 and the second conductive fixing member; and in the embodiment of the present application, x 2 ×S 2 / E is 0.2 to 0.7, so that the current-carrying capacity of the second electrode terminal 32 is relatively strong, which can effectively reduce the internal resistance of the battery cell 7, reduce the heat generation of the battery cell 7, and thus improve the fast charging ability of the battery cell 7.

[0142] Exemplarily, x 2 ×S 2 / E, this formula only performs numerical calculations without substituting units, x 2 ×S 2 / E is 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7 or a range composed of any two of the above numerical values.

[0143] In some embodiments, the second electrode terminal 32 is at least one, and can be optionally at least two. For example, x 2 is expressed as any positive integer from 1 to 4. x 2 ×S 2 can characterize the current-carrying capacity of all the second electrode terminals 32 in the battery cell 7.

[0144] In some embodiments, the structural form of the second electrode terminal 32 is the same as that of the first electrode terminal 31. For example, the second electrode terminal 32 may include a second main body portion and a second protruding portion. The second main body portion penetrates the housing, and the second conductive fixing member is disposed around the second main body portion; the second protruding portion is disposed on the second main body portion and protrudes from the second main body portion to be connected to the side of the housing facing the electrode assembly 10. In other embodiments, the second electrode terminal 32 may only include the second main body portion, and the second main body portion penetrates the end cover 22 and is connected to the tab.

[0145] Optionally, in the direction from the second main body portion towards the second protruding portion, the size of the second protruding portion is 1.5 mm to 3.0 mm. When the second electrode terminal 32 is disposed on the end cap 22, the direction from the second main body portion towards the second protruding portion may be parallel to the width direction Y of the battery cell 7. In this case, the size of the second protruding portion along the width direction Y is 1.5 mm to 3.0 mm.

[0146] When the second protruding portion satisfies the above conditions, the connection area between the second protruding portion and the housing is relatively larger, the connection strength is higher, and the structure makes the structure of the battery cell 7 more stable.

[0147] Optionally, the ratio of the size of the second main body portion along the thickness direction X of the battery cell 7 to the size of the end cap 22 along the thickness direction X of the battery cell 7 is 0.20 to 0.40, such as 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16, 0.18, 0.20, 0.22, 0.24, 0.26, 0.28, 0.30, 0.32, 0.34, 0.36, 0.38, 0.40 or the range composed of any two of the above values; in the embodiment of the present application, the size of the second main body portion refers to the size of the second main body portion of a single second electrode terminal 32.

[0148] When the second main body portion satisfies the above conditions, the size ratio of the second main body portion is relatively high, which is beneficial to improving the current-carrying capacity of the second electrode terminal 32, thereby improving the fast charging performance.

[0149] The housing assembly 20 further includes a second conductive fixing member, which is disposed around the second electrode terminal 32 and fixedly connects the second electrode terminal 32 and the end cap 22.

[0150] The second conductive fixing member can further increase the current-carrying area between the battery cell 7 and the external bus bar assembly, thereby improving the current-carrying capacity, which is beneficial to improving the current-carrying capacity of the battery device and improving the fast charging performance of the battery device.

[0151] Optionally, a part of the second main body portion protrudes from the side of the end cap 22 facing away from the electrode assembly 10, and the second conductive fixing member is disposed around the second main body portion.

[0152] Optionally, the ratio of the dimension of the second conductive fixing member in the thickness direction X to the dimension of the end cap 22 in the thickness direction X is 0.40 to 0.80, such as 0.40, 0.42, 0.44, 0.46, 0.48, 0.50, 0.52, 0.54, 0.56, 0.58, 0.60, 0.62, 0.64, 0.66, 0.68, 0.70, 0.72, 0.74, 0.76, 0.78, 0.80 or the range composed of any two of the above values; in the embodiment of the present application, the thickness direction X refers to the thickness direction X of the battery cell 7.

[0153] When the second conductive fixing member meets the above conditions, the size ratio of the second conductive fixing member is relatively high, which is beneficial to increasing the current-carrying area between the battery cell 7 and the external busbar assembly, thereby improving the current-carrying capacity, which is beneficial to improving the current-carrying capacity of the battery device and improving the fast-charging performance of the battery device.

[0154] As Figure 10 shown, in some embodiments, at least one first electrode terminal 31 is disposed on at least one side of the electrode assembly 10 in the width direction Y. This arrangement can shorten the electron migration path and is beneficial to improving the fast-charging performance.

[0155] For example, all the first electrode terminals 31 are disposed on one side of the electrode assembly 10 in the width direction Y.

[0156] Again, for example, multiple first electrode terminals 31 are disposed on both sides of the electrode assembly 10 in the width direction Y.

[0157] As Figure 11 shown, in some embodiments, at least one first electrode terminal 31 is disposed on at least one side of the electrode assembly 10 in the length direction Z.

[0158] For example, all the first electrode terminals 31 are disposed on one side of the electrode assembly 10 in the length direction Z.

[0159] Again, for example, multiple first electrode terminals 31 are respectively disposed on both sides of the electrode assembly 10 in the length direction Z. This arrangement can shorten the electron migration path and is beneficial to improving the fast-charging performance.

[0160] Exemplarily, there are two first electrode terminals 31, one of the first electrode terminals 31 is disposed on one side of the electrode assembly 10, and the other first electrode terminal 31 is disposed on the other side of the electrode assembly 10. Or, exemplarily, there are four first electrode terminals 31, two of the first electrode terminals 31 are disposed on one side of the electrode assembly 10, and the other two first electrode terminals 31 are disposed on both sides of the electrode assembly 10.

[0161] The first tab 111 is electrically connected to the first electrode terminal 31, which can be directly connected or indirectly connected. When the first tab 111 and the first electrode terminal 31 are indirectly connected, the battery cell 7 may include a first adapter 51, which is located between the first electrode terminal 31 and the first tab 111 and connects the first electrode terminal 31 and the first tab 111.

[0162] For example, when the first electrode terminal 31 is disposed on at least one side of the electrode assembly 10 along the length direction Z, and the first tab 111 is disposed on at least one side of the first coating portion 112 along the width direction Y, the connection between the first tab 111 and the first electrode terminal 31 is more facilitated by the first adapter 51.

[0163] In the case where the first tab 111 and the first electrode terminal 31 are respectively disposed on different sides of the battery cell 7, the first adapter 51 may include a first adapter portion 511 and a second adapter portion 512. The first adapter portion 511 extends along the length direction Z, the first adapter portion 511 connects the first tab 111, the second adapter portion 512 is connected to the first adapter portion 511 and protrudes from the first adapter portion 511 along the width direction Y, and is connected to the first electrode terminal 31.

[0164] In the case where the first tab 111 and the first electrode terminal 31 are disposed on the same side of the battery cell 7, the first adapter 51 may only include the first adapter portion 511.

[0165] In the above embodiments, the first adapter 51 may be in a sheet structure, and of course, it may also be in other structural forms.

[0166] In the above embodiments, the first adapter 51 may include a conductive polymer or a conductive metal material. The conductive metal material may include copper, aluminum, or an alloy containing the above metal elements, etc.

[0167] In some embodiments, the battery cell 7 further includes a first conductive member 61, which is located between the first adapter 51 and the first tab 111. The arrangement of the first conductive member 61 can increase the current-carrying capacity between the first tab 111 and the first adapter 51, facilitate the improvement of the fast charging performance, and reduce the heat generation.

[0168] For example, the tab portion of the first electrode sheet 11 is disposed on one side of the coating portion along the width direction Y; the first conductive member 61 is located between the first adapter 51 and the first tab 111 and connects the first adapter 51 and the first tab 111.

[0169] Optionally, there are at least two first tabs 111 and at least two first conductive members 61. The first conductive members 61 and the first tabs 111 are connected in a one-to-one correspondence. The at least two first conductive members 61 are connected to the first adapter 51. This connection method is beneficial to improving the weight energy density of the battery cell 7.

[0170] Optionally, there are at least two first tabs 111 on the same side of the first coating portion 112. The first conductive member 61 can be a continuous sheet structure that connects at least two first tabs 111.

[0171] As Figure 12 shown, when the first tab 111 and the first electrode terminal 31 are respectively disposed on different sides of the battery cell 7, optionally, the first conductive member 61 includes a first conductive portion 611 and a second conductive portion 612. The first conductive portion 611 extends along the length direction Z. The first conductive portion 611 connects the first tab 111 and the first adapter 51. The second conductive portion 612 is connected to the first conductive portion 611 and protrudes from the first conductive portion 611 along the width direction Y. The second conductive portion 612 connects the first adapter 51. This structural arrangement is beneficial to increasing the grouping space in the length direction Z and is beneficial to improving the energy density of the battery device.

[0172] It should be noted that when the battery cell 7 does not include the first adapter 51, the first tab 111 can be connected to the first electrode terminal 31 through the first conductive member 61.

[0173] Exemplarily, the first conductive member 61 has conductivity and can include a conductive polymer or a conductive metal material. The conductive metal material can include copper, aluminum, or an alloy containing the above metal elements, etc.

[0174] In some embodiments, at least one second electrode terminal 32 is disposed on at least one side of the electrode assembly 10 along the width direction Y. This arrangement can shorten the electron migration path and is beneficial to improving the fast charging performance.

[0175] For example, all the second electrode terminals 32 are disposed on one side of the electrode assembly 10 along the width direction Y. In this case, the first electrode terminal 31 and the second electrode terminal 32 can be respectively disposed on both sides of the electrode assembly 10 along the width direction Y and will not interfere with each other when electrically connected to the tab portions respectively.

[0176] Exemplarily, there are two first electrode terminals 31 and two second electrode terminals 32. The two first electrode terminals 31 are disposed on one side of the electrode assembly 10 along the width direction Y, and the two second electrode terminals 32 are disposed on the other side of the electrode assembly 10 along the width direction Y.

[0177] For another example, a plurality of second electrode terminals 32 are respectively disposed on both sides of the electrode assembly 10 along the width direction Y. This setting method can further shorten the migration path of electrons and is beneficial to improving the fast charging performance. In this case, the first electrode terminal 31 and the second electrode terminal 32 are disposed on one side of the electrode assembly 10 along the width direction Y, and the first electrode terminal 31 and the second electrode terminal 32 are disposed on the other side of the electrode assembly 10 along the width direction Y.

[0178] In some embodiments, at least one second electrode terminal 32 is disposed on at least one side of the electrode assembly 10 along the length direction Z.

[0179] For example, at least two second electrode terminals 32 are respectively disposed on both sides of the electrode assembly 10 along the length direction Z. This setting method can shorten the migration path of electrons and is beneficial to improving the fast charging performance. In this case, the first electrode terminal 31 and the second electrode terminal 32 are disposed on one side of the electrode assembly 10 along the length direction Z, and the first electrode terminal 31 and the second electrode terminal 32 are disposed on the other side of the electrode assembly 10 along the length direction Z.

[0180] Exemplarily, there are two second electrode terminals 32. One of the second electrode terminals 32 is disposed on one side of the electrode assembly 10 along the length direction Z, and the other second electrode terminal 32 is disposed on the other side of the electrode assembly 10 along the length direction Z. There are two first electrode terminals 31. One of the first electrode terminals 31 is disposed on one side of the electrode assembly 10, and the other first electrode terminal 31 is disposed on both sides of the electrode assembly 10. Figure 12 A schematic diagram showing four electrode terminals is shown.

[0181] For another example, all the second electrode terminals 32 are disposed on one side of the electrode assembly 10 along the length direction Z. In this case, the first electrode terminal 31 and the second electrode terminal 32 can be respectively disposed on both sides of the electrode assembly 10 along the length direction Z, and there will be no mutual interference when electrically connecting to the tab portions respectively.

[0182] Exemplarily, the first electrode terminal 31 and the second electrode terminal 32 are each one, the first electrode terminal 31 and the second electrode terminal 32 are respectively located on both sides of the electrode assembly along the length direction Z, and the first electrode terminal 31 and the second electrode terminal 32 are arranged offset along the width direction Y. Specifically, in the case where all the second tab ears 121 are arranged on the same side of the second coating portion 122 along the width direction Y, and all the first tab ears 111 are arranged on the same side of the first coating portion 112 along the width direction Y, the first tab ear 111 and the second tab ear 121 are respectively arranged on both sides of the coating portion along the width direction Y, the first electrode terminal 31 is arranged close to the first tab ear 111, and the second electrode terminal 32 is arranged close to the second tab ear 121. This setting method makes the electron transmission distance shorter and is more conducive to improving the fast charging ability of the battery cell 7. Figure 11 The schematic diagram showing that there are two electrode terminals is shown.

[0183] The second tab ear 121 and the second electrode terminal 32 are electrically connected, and can be directly connected or indirectly connected; when the second tab ear 121 and the second electrode terminal 32 are indirectly connected, the battery cell 7 may include a second adapter, and the second adapter is located between the second electrode terminal 32 and the second tab ear 121 and connects the second electrode terminal 32 and the second tab ear 121.

[0184] For example, when the second electrode terminal 32 is arranged on at least one side of the electrode assembly 10 along the length direction Z, and the second tab ear 121 is arranged on at least one side of the second coating portion 122 along the width direction Y, it is more conducive to the connection between the second tab ear 121 and the second electrode terminal 32 through the second adapter.

[0185] In the case where the second tab ear 121 and the second electrode terminal 32 are respectively arranged on different sides of the battery cell 7, the second adapter may include a first connection portion and a second connection portion, the first connection portion extends along the length direction Z, the first connection portion connects the second tab ear 121, the second connection portion is connected to the first connection portion and protrudes from the first connection portion along the width direction Y and is connected to the second electrode terminal 32.

[0186] In the case where the second tab ear 121 and the second electrode terminal 32 are arranged on the same side of the battery cell 7, the second adapter may only include the first connection portion.

[0187] In the above embodiments, the second adapter may be a sheet-like structure, and of course, it may also be other structural forms.

[0188] In the above embodiments, the second adapter may include a conductive polymer or a conductive metal material, and the conductive metal material may include copper, aluminum, or an alloy containing the above metal elements, etc.

[0189] In some embodiments, the battery cell 7 further includes a second conductive member located between the second adapter and the second tab 121. The provision of the second conductive member can increase the current-carrying capacity between the second tab 121 and the second adapter, which is beneficial to improving the fast-charging performance and reducing heat generation.

[0190] For example, the tab portion of the second electrode plate 12 is provided on one side of the coating portion along the width direction Y; the second conductive member is located between the second adapter and the second tab 121 and connects the second adapter and the second tab 121.

[0191] Optionally, there are at least two second tabs 121 on the same side of the second coating portion 122. The second conductive member can be a continuous sheet structure connecting at least two second tabs 121; or there are at least two second conductive members, and the second conductive members are connected to the second tabs 121 in a one-to-one correspondence, and at least two second conductive members are connected to the second adapter. This connection method is beneficial to improving the weight energy density of the battery cell 7.

[0192] When the second tab 121 and the second electrode terminal 32 are respectively provided on different sides of the battery cell 7, optionally, the second conductive member includes a third conductive portion and a fourth conductive portion. The third conductive portion extends along the length direction Z and connects the tab portion of the second electrode plate 12 and the second adapter. The fourth conductive portion is connected to the third conductive portion and protrudes from the third conductive portion along the width direction Y, and the third conductive portion connects the second adapter. This structural arrangement is beneficial to increasing the grouping space in the length direction Z and improving the energy density of the battery device.

[0193] Exemplarily, the second conductive member has conductivity and can include a conductive polymer or a conductive metal material. The conductive metal material can include copper, aluminum, or an alloy containing the above metal elements, etc.

[0194] It should be noted that when the battery cell 7 does not include the second adapter, the second tab 121 can be connected to the second electrode terminal 32 through the second conductive member.

[0195] In some embodiments, the housing 21 includes two first housing parts 211, a second housing part 212, and a third housing part 213. The two first housing parts 211 are opposite to each other along the thickness direction X of the battery cell 7. The second housing part 212 and the third housing part 213 are opposite to each other, and the second housing part 212 and the third housing part 213 are connected by the first housing parts 211. The second housing part 212 includes a first wall 2121 and a second wall 2122 that are continuously arranged along the thickness direction X, and the first wall 2121 and the second wall 2122 are welded. The first wall 2121 and the second wall 2122 can be welded specifically by methods such as butt welding and laser welding, and butt welding is optional. Since the area of the second housing part 212 is relatively small and the degree of expansion is relatively small, and the weld seam is located on the second housing part 212, the risk of liquid leakage of the battery cell 7 can be reduced.

[0196] When assembling the battery cell 7 into the box body of the battery device, the battery cell 7 is arranged inside the box body. The box body includes a first box body part and a second box body part, and the first box body part covers the second box body part; wherein, the second housing part 212 is arranged opposite to the first box body part, and the second housing part 212 is arranged close to the first box body part, and the third housing part 213 is arranged close to the second box body part. When assembling the battery device into the electrical device, the first box body part can be located above the second box body part in the vertical direction. Since the second housing part 212 has a weld seam and the weld seam is arranged upward, the risk of liquid leakage of the battery cell 7 is reduced.

[0197] In some embodiments, the dimension of the battery cell 7 along the thickness direction X is 10 mm to 30 mm, such as 10 mm, 12 mm, 14 mm, 15 mm, 16 mm, 18 mm, 20 mm, 22 mm, 24 mm, 25 mm, 26 mm, 28 mm, 30 mm or the range composed of any two of the above values.

[0198] 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 beneficial to the rapid heat dissipation inside the battery cell 7 and reduces the risk of thermal runaway.

[0199] In some embodiments, the thickness of the housing 21 is from 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, 0.3 mm, 0.31 mm, 0.32 mm, 0.33 mm, 0.34 mm, 0.35 mm, 0.36 mm, 0.37 mm, 0.38 mm, 0.39 mm, 0.4 mm, 0.41 mm, 0.42 mm, 0.43 mm, 0.44 mm, 0.45 mm, 0.46 mm, 0.47 mm, 0.48 mm, 0.49 mm, 0.5 mm or a range formed by any two of the above values. Optionally, the thickness of the housing 21 is from 0.3 mm to 0.4 mm.

[0200] When the thickness of the housing 21 is within the above range, the housing 21 is relatively thin, which is beneficial to the rapid heat dissipation of the housing 21.

[0201] Exemplarily, the thickness of the first housing portion 211 is from 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, 0.3 mm, 0.31 mm, 0.32 mm, 0.33 mm, 0.34 mm, 0.35 mm, 0.36 mm, 0.37 mm, 0.38 mm, 0.39 mm, 0.4 mm, 0.41 mm, 0.42 mm, 0.43 mm, 0.44 mm, 0.45 mm, 0.46 mm, 0.47 mm, 0.48 mm, 0.49 mm, 0.5 mm or a range formed by any two of the above values. Optionally, the thickness of the housing 21 is from 0.3 mm to 0.4 mm.

[0202] Exemplarily, the thickness of the second housing portion 212 is from 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, 0.3 mm, 0.31 mm, 0.32 mm, 0.33 mm, 0.34 mm, 0.35 mm, 0.36 mm, 0.37 mm, 0.38 mm, 0.39 mm, 0.4 mm, 0.41 mm, 0.42 mm, 0.43 mm, 0.44 mm, 0.45 mm, 0.46 mm, 0.47 mm, 0.48 mm, 0.49 mm, 0.5 mm or a range composed of any two of the above values. Optionally, the thickness of the housing 21 is from 0.3 mm to 0.4 mm.

[0203] Exemplarily, the thickness of the third housing portion 213 is from 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, 0.3 mm, 0.31 mm, 0.32 mm, 0.33 mm, 0.34 mm, 0.35 mm, 0.36 mm, 0.37 mm, 0.38 mm, 0.39 mm, 0.4 mm, 0.41 mm, 0.42 mm, 0.43 mm, 0.44 mm, 0.45 mm, 0.46 mm, 0.47 mm, 0.48 mm, 0.49 mm, 0.5 mm or a range composed of any two of the above values. Optionally, the thickness of the housing 21 is from 0.3 mm to 0.4 mm.

[0204] Heat conduction member In some embodiments, the battery cell 7 further includes a heat conduction member. There is a gap between the tab portion and the coating portion, and the heat conduction member is disposed in the gap between the tab portion and the coating portion. The heat conduction member can conduct the heat generated by the tab portion, quickly transfer the heat generated by the tab portion, and reduce the risk of ablation of the separator in the electrode assembly.

[0205] Optionally, the heat conduction member further contacts the housing 21, so that the heat diffuses from the housing 21.

[0206] Such as Figure 13As shown, exemplarily, the heat conduction member includes a first heat conduction member 81 disposed in the gap between the first tab 111 and the first coating portion 112, and the first heat conduction member 81 can conduct the heat generated by the first tab 111.

[0207] Optionally, the first heat conduction member 81 can further be disposed in the gap between the first tab 111 and the first electrode terminal 31. When the battery cell 7 includes a first adapter 51, the first heat conduction member 81 can also be disposed in the gap between the first tab 111 and the first adapter 51, or in the gap between the second adapter portion 512 of the first adapter 51 and the coating portion.

[0208] Exemplarily, the heat conduction member includes a second heat conduction member disposed in the gap between the second tab 121 and the second coating portion 122, and the second heat conduction member can conduct the heat generated by the second tab 121.

[0209] Optionally, the second heat conduction member can further be disposed in the gap between the second tab 121 and the second electrode terminal 32. When the battery cell 7 includes a second adapter, the second heat conduction member can also be disposed in the gap between the second tab 121 and the second adapter.

[0210] The main material of the heat conduction member includes one or more of polyimide PI and polyethylene terephthalate PET.

[0211] [First electrode plate and second electrode plate] In some embodiments, the battery cell 7 also satisfies: M 1 / E is 0.2 to 0.6, M 1 represents the area of the first connection region, and its unit is mm 2 ; the first connection region is the region where at least one first electrode terminal 31 is connected to the tab portion of the first electrode plate, that is, the sum of the regions where all first electrode terminals 31 are connected to the first tab 111. When welding is used, M 1 can represent the weld mark area of the first electrode terminal 31, and this weld mark area is the welding area between the first electrode terminal 31 and the first tab 111.

[0212] When the battery cell 7 satisfies the above conditions, the current conduction ability between the first electrode terminal 31 and the first tab 111 is strong, which is beneficial to reducing the internal resistance of the battery cell 7, reducing the heat generation of the battery cell 7, and thus improving the fast charging ability of the battery cell 7.

[0213] In some embodiments, M 1 mm 2 is 60 mm2 to 120 mm 2 , such as 60 mm², 70 mm², 80 mm², 90 mm², 100 mm², 110 mm², 120 mm², or a range composed of any two of the above values. The current conduction ability between the first electrode terminal 31 and the first tab 111 is strong, which is beneficial to reducing the internal resistance of the battery cell 7, reducing the heat generation of the battery cell 7, thereby improving the fast charging ability of the battery cell 7 and enabling the battery cell 7 to quickly reach the required capacity.

[0214] In some embodiments, the battery cell 7 further satisfies: M 2 / E is 0.2 to 0.6, M 2 represents the area of the second connection region, and its unit is mm 2 ; the second connection region is the region where at least one second electrode terminal 32 is connected to the tab portion of the second electrode plate, that is, the sum of the regions where all the second electrode terminals 32 are connected to the second tab 121.

[0215] When the battery cell 7 satisfies the above conditions, the current conduction ability between the second electrode terminal 32 and the second tab 121 is strong, which is beneficial to reducing the internal resistance of the battery cell 7, reducing the heat generation of the battery cell 7, thereby improving the fast charging ability of the battery cell 7 and enabling the battery cell 7 to quickly reach the required capacity.

[0216] In some embodiments, M 2 mm 2 is 60 mm 2 to 120 mm 2 , such as 60 mm², 70 mm², 80 mm², 90 mm², 100 mm², 110 mm², 120 mm², or a range composed of any two of the above values. The current conduction ability between the second electrode terminal 32 and the second tab 121 is strong, which is beneficial to reducing the internal resistance of the battery cell 7, reducing the heat generation of the battery cell 7, thereby improving the fast charging ability of the battery cell 7.

[0217] In some embodiments, the first tab 111 is disposed on at least one side of the first coating portion 112 along the first direction.

[0218] As shown in Figure 14 and Figure 15 , in some embodiments, the first electrode plate 11 satisfies: n*W1 / W2 is 0.5 to 1.0; n represents the number of all tab portions located on the same side of the coating portion; W1 represents the average dimension of the tab portion along the second direction, and the first direction is perpendicular to the second direction; W2 represents the dimension of the coating portion along the second direction.

[0219] Exemplarily, n*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 composed of any two of the above values.

[0220] In the embodiment of the present application, the first pole piece 11 further satisfies that n*W1 / W2 is from 0.5 to 1.0, so that the connection area between the pole ear part and the coating part is relatively large, and the current-carrying area of the pole ear part is relatively large, which is beneficial to reducing the DC resistance and reducing heat generation; the first electrode terminal 31 is at least two. In other words, at least two first electrode terminals 31 are connected to the pole ear part of the first pole piece 11, which can further increase the current-carrying area of the first electrode terminal 31 and the pole ear part, further reduce the DC resistance, and reduce heat generation, thereby being beneficial to achieving fast charging.

[0221] W1 represents the average dimension of the first pole ear 111 along the second direction. When the first pole ear 111 is of a special-shaped structure, for example, along the first direction, the dimension of the first pole ear 111 along the second direction gradually increases. In this case, the dimensions of the first pole ear 111 at multiple positions along the second direction can be measured, and thus the average dimension of the first pole ear 111 along the second direction can be calculated. Of course, the dimensions of the first pole ear 111 at each position along the second direction can be the same value. In this case, this value can be used as the average dimension of the first pole ear 111.

[0222] The first pole ear 111 can be one or more. For example, n is from 1 to 4. When there are multiple first pole ears 111, after measuring the average dimensions of each first pole ear 111 respectively, the average dimension of the first pole ear 111 can be calculated by adding the average dimensions and dividing by the number of the first pole ears 111.

[0223] The first pole ear 111 is connected to the first coating part 112. The first pole ear 111 includes a first end 1111 connected to the first coating part 112. When n*W1 / W2 satisfies the above range, it means that the cross-section of the first end 1111 along the thickness direction of the first pole ear 111 itself is relatively large, the contact surface between the first pole ear 111 and the first coating part 112 is relatively large, the current-carrying capacity of the first pole ear 111 is strong, and the power performance and cycle performance of the battery cell 7 can be improved.

[0224] Optionally, the current collector part of the first pole ear 111 and the first coating part 112 is an integral structure, so that the internal resistance of the first pole piece 11 is relatively low, and the power performance and cycle performance of the battery cell 7 can be further improved.

[0225] Optionally, W2 is from 300 mm to 650 mm, such as 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, 550 mm, 600 mm, 650 mm, or a range composed of any two of the above values.

[0226] Optionally, n*W1 is from 150 mm to 650 mm, such as 150 mm, 200 mm, 250 mm, 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, 550 mm, 600 mm, 650 mm, or a range composed of any two of the above values.

[0227] In the embodiments of the present application, the first direction, the second direction, and the thickness direction X of the battery cell 7 are perpendicular to each other in pairs. The first direction may be parallel to the length direction of the battery cell 7 or parallel to the width direction of the battery cell 7.

[0228] When the first direction is parallel to the length direction Z of the battery cell 7, the dimension of the component in this direction can be regarded as the length of the component. For example, the dimension of the coating portion along the first direction is the length of the coating portion. In this case, the second direction is parallel to the width direction Y of the battery cell 7.

[0229] When the first direction is parallel to the width direction Y of the battery cell 7, the dimension of the component in this direction can be regarded as the width of the component. For example, the dimension of the coating portion along the first direction is the width of the coating portion. In this case, the second direction is parallel to the length of the battery cell 7.

[0230] Figure 14 and Figure 15 shows that the first direction is parallel to the width direction Y and the second direction is parallel to the length direction Z. Figure 14 In, n is 1, W1 can also represent the dimension of a single first tab 111, and W2 represents the dimension of the first coating portion 112 along the second direction. Figure 15 In, n is 4, and the dimensions of each first tab 111 are the same. W1 can represent the dimension of a single first tab 111. Of course, the dimensions of each first tab 111 can also vary slightly.

[0231] When the first electrode sheet 11 is a positive electrode sheet, the dimension of the coating portion of the positive electrode sheet along the length direction Z of the battery cell 7 is the first dimension, and the dimension of the coating portion of the positive electrode sheet along the width direction Y of the battery cell 7 Figure 14 in which W2 represents the dimension of the coating portion of the positive electrode sheet along the length direction Z, and Y1 represents the dimension of the coating portion of the positive electrode sheet along the width direction Y.

[0232] When the ratio of the length to the width of the coated portion of the positive electrode tab is too small, for example, less than 4, the loading of the active material is relatively small, which is not conducive to improving the energy density of the battery cell; when the ratio of the length to the width of the coated portion of the positive electrode tab is too large, for example, greater than 7, the length of the coated portion of the positive electrode tab is too long, and the transmission path of electrons in the length direction of the positive electrode tab is too long, resulting in an increase in resistance, which is not conducive to improving the fast charging performance of the battery cell.

[0233] When the ratio of the length to the width of the coated portion of the positive electrode tab is 4 to 7, for example, 4, 4.5, 5, 5.5, 6, 6.5, 7 or the range composed of any two of the above values, it is possible to balance the improvement of the energy density and fast charging performance of the battery cell.

[0234] In some embodiments, the length of the coated portion of the positive electrode tab is 300 mm to 650 mm, for example, 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, 550 mm, 600 mm, 650 mm or the range composed of any two of the above values. Optionally, the length of the coated portion of the positive electrode tab is 400 mm to 500 mm. When the length of the coated portion of the positive electrode tab meets the above range, it is possible to balance the improvement of the energy density and fast charging performance of the battery cell.

[0235] Next, the related solutions in which the first direction is parallel to the width direction Y of the first tab 11 will be described.

[0236] As Figure 15 shown, in some embodiments, the first tab 11 includes one or more first tab ears 111, and one or more first tab ears 111 are disposed on at least one side of the coated portion along the width direction Y.

[0237] For example, one or more first tab ears 111 are disposed on one side of the first coated portion 112 along the width direction Y. In this case, it can be understood that all the first tab ears 111 are disposed on the same side of the first coated portion 112 along the width direction Y. This kind of arrangement is beneficial to increasing the occupied space of the electrode assembly 10, thereby improving the energy density of the battery cell 7. When all the first tab ears 111 are disposed on the same side of the first coated portion 112 along the width direction Y, the size of the first coated portion 112 along the width direction Y is 80 mm to 150 mm.

[0238] Figure 15 In Figure 15 , Y1 represents the size of the first coated portion 112 along the width direction Y, and can also be understood as the width of the first coated portion 112.

[0239] As Figure 16As shown, for example, in the case where the first pole piece 11 includes a plurality of first pole tabs 111, the plurality of first pole tabs 111 are disposed on both sides of the first coating portion 112 along the width direction Y.

[0240] When the plurality of first pole tabs 111 are disposed on both sides of the first coating portion 112 along the width direction Y, the dimension of the first coating portion 112 along the width direction Y is 80 mm to 150 mm.

[0241] Figure 16 In the figure, Y1 represents the dimension of the first coating portion 112 along the width direction Y, and can also be understood as the width of the first coating portion 112.

[0242] Whether all the first pole tabs 111 are disposed on the same side of the first coating portion 112 along the width direction Y, or all the first pole tabs 111 are respectively disposed on both sides of the first coating portion 112 along the width direction Y, at least two first pole tabs 111 on the same side of the first coating portion 112 can be selected, such as two, three, four, five, six, etc.; four can be selected. This setting is beneficial to the uniform distribution of electrons in the first pole piece 11 and is beneficial to improving the fast charging performance.

[0243] Optionally, the distance between adjacent two pole tab portions along the length direction Z is greater than 0 and less than or equal to 300 mm, such as 100 mm, 120 mm, 140 mm, 150 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 250 mm, 260 mm, 280 mm, 300 mm or the range composed of any two of the above values. Figure 16 In the figure, Z1 represents the distance between adjacent two pole tab portions along the length direction Z.

[0244] Next, the related solutions where the first direction is parallel to the length direction of the first pole piece 11 will be described.

[0245] As Figure 17 shown, in some embodiments, the first pole piece 11 includes one or more first pole tabs 111; the one or more first pole tabs 111 are disposed on at least one side of the first coating portion 112 along the length direction Z.

[0246] For example, the one or more first pole tabs 111 are disposed on one side of the first coating portion 112 along the length direction Z. In this case, it can be understood that all the first pole tabs 111 are disposed on the same side of the first coating portion 112 along the length direction Z.

[0247] When all the first pole tabs 111 are disposed on the same side of the first coating portion 112 along the length direction Z, the dimension of the first coating portion 112 along the length direction Z is 80 mm to 150 mm.

[0248] Figure 17Among them, Z2 represents the dimension of the first coating portion 112 in the length direction Z, and can also be understood as the length of the first coating portion 112.

[0249] As Figure 18 shown, for example, in the case where the first pole piece 11 includes a plurality of first pole tabs 111, the plurality of first pole tabs 111 are respectively arranged on both sides of the first coating portion 112 in the length direction Z.

[0250] Optionally, the plurality of first pole tabs 111 are respectively arranged on both sides of the first coating portion 112 in the length direction Z. This arrangement can shorten the transmission path of electrons in the first pole piece 11, which is beneficial to improving the fast charging performance.

[0251] In the case where the plurality of first pole tabs 111 are respectively arranged on both sides of the first coating portion 112 in the length direction Z, the dimension of the first coating portion 112 in the length direction Z is 300 mm to 650 mm.

[0252] Figure 18 Among them, Z3 represents the dimension of the first coating portion 112 in the length direction Z, and can also be understood as the length of the first coating portion 112.

[0253] Whether all the first pole tabs 111 are arranged on the same side of the first coating portion 112 in the width direction Y, or all the first pole tabs 111 are respectively arranged on both sides of the first coating portion 112 in the width direction Y, at least two first pole tabs 111 on the same side of the first coating portion 112 can be selected, such as two, three, four, five, six, etc. This arrangement is beneficial to the uniform distribution of electrons in the first pole piece 11, which is beneficial to improving the fast charging performance.

[0254] Optionally, the distance between adjacent two pole tab portions in the width direction Y is greater than 0 and less than or equal to 300 mm, such as 100 mm, 120 mm, 140 mm, 150 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 250 mm, 260 mm, 280 mm, 300 mm or the range composed of any two of the above values. This setting method can further shorten the electron transmission path, effectively reduce the internal resistance of the battery cell, and each pole tab bears less current, and the current distribution is more uniform. Figure 10 Among them, Y2 represents the distance between adjacent two pole tab portions in the width direction Y. Figure 17 Among them, Y2 represents the distance between adjacent two pole tab portions in the width direction Y.

[0255] In the embodiments of the present application, the number and arrangement manner of the second pole tabs 121 are the same as those of the first pole tabs 111, which will not be elaborated here. The structure of the second pole piece 12 is the same as that of the first pole piece 11, which will not be elaborated here. [Electrolyte] During the charging and discharging process of a battery cell, active ions such as lithium ions are inserted and extracted back and forth between the positive electrode plate and the negative electrode plate, and the electrolyte plays a role in conducting active ions between the positive electrode plate and the negative electrode plate.

[0256] The electrolyte salt includes a lithium salt, the lithium salt includes lithium bis(fluorosulfonyl)imide, and may further include lithium hexafluorophosphate LiPF 6 . The above lithium salt is beneficial to increasing the total number of lithium ion migrations in the electrolyte, improving the ability to lithium ions, and enhancing the kinetic performance of the battery cell.

[0257] Optionally, based on the mass of the electrolyte, the ratio of the mass content of lithium hexafluorophosphate to the mass content of lithium bis(fluorosulfonyl)imide is 0.5 to 4, and may be 1.2 to 2.0. The lithium salt is beneficial to increasing the total number of lithium ion migrations in the electrolyte, improving the ability to lithium ions, and enhancing the kinetic performance of the battery cell.

[0258] Exemplarily, the mass content of lithium hexafluorophosphate and the mass content of lithium bis(fluorosulfonyl)imide 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 the range composed of any two of the above values.

[0259] In the embodiments of the present application, based on the mass of the electrolyte, the mass content of lithium bis(fluorosulfonyl)imide is 1% to 15%, and may be 3% to 12%. When the lithium salt meets the above conditions, it is beneficial to increasing the total number of lithium ion migrations in the electrolyte, improving the ability to lithium ions, and enhancing the kinetic performance of the battery cell.

[0260] Exemplarily, based on the mass of the electrolyte, the mass content of lithium bis(fluorosulfonyl)imide is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or the range composed of any two of the above values.

[0261] In some embodiments, based on the mass of the electrolyte, the mass content of the lithium salt is 13% to 20%, such as 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20% or the range composed of any two of the above values. When the mass content of the lithium salt is within the above range, the lithium salt is beneficial to increasing the conductivity of the electrolyte and enhancing the kinetic performance of the battery cell.

[0262] In some embodiments, the conductivity of the electrolyte at room temperature is from 10 mS / cm to 13 mS / cm. Exemplarily, the conductivity of the electrolyte 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 a range composed of any two of the above values.

[0263] 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.

[0264] In the embodiments of the present application, the conductivity of the electrolyte at room temperature, such as 25 °C, is the ionic conductivity, and it can be detected by using the equipment and methods well-known in the art. For example, it can be tested with reference to the industry standard HG-T 4067-2015.

[0265] In some embodiments, the organic solvent includes carbonate solvents.

[0266] Optionally, the mass content of the carbonate solvent in the electrolyte is from 10% to 80%. Exemplarily, the mass content of the carbonate solvent in the organic solvent is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80%, or a range composed of any two of the above values. The carbonate solvent with the above mass content can further increase the conductivity of the electrolyte at room temperature, which is beneficial to the migration of lithium ions; moreover, the mass content of the carbonate solvent is not too high, which can reduce the gas generation at high temperature and improve the high-temperature cycle performance.

[0267] Optionally, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Further optionally, the carbonate solvent includes one or more of dimethyl carbonate and ethylene carbonate. Even more optionally, the carbonate solvent includes dimethyl carbonate. The above carbonate solvent and the chain carboxylic acid ester solvent are used in combination, which increases the conductivity of the electrolyte at room temperature and is beneficial to the migration of lithium ions.

[0268] In some embodiments, the organic solvent includes chain carboxylic acid ester solvents.

[0269] Optionally, the mass content of the chain carboxylic acid ester solvent in the electrolyte is from 5% to 30%. Exemplarily, the mass content of the chain carboxylic acid ester solvent is 5%, 10%, 15%, 20%, 25%, 30%, or a range composed of any two of the above values.

[0270] When the mass content of the chain carboxylic acid ester solvent is within the above range, the viscosity of the electrolyte system is relatively small, which is beneficial to the migration of lithium ions; moreover, the mass content of the chain carboxylic acid ester solvent is not too high, which can reduce the gas generation at high temperature and improve the high-temperature cycle performance.

[0271] In some embodiments, the chain carboxylic acid ester solvent includes a compound represented by Formula I, Formula I, In Formula I, R 1 includes a hydrogen atom, a C1-C5 alkyl group or a C1-C5 haloalkyl group, R 2 includes a C1-C5 alkyl group or a C1-C5 haloalkyl group.

[0272] The above chain carboxylic acid ester solvent has a relatively high conductivity, which is beneficial to improving the fast charging ability of the battery monomer.

[0273] Optionally, R 1 includes a hydrogen atom, a C1-C3 alkyl group or a C1-C3 haloalkyl group. Further optionally, R 1 includes a hydrogen atom, a halogen atom, a C1-C2 alkyl group or a C1-C2 haloalkyl group.

[0274] Optionally, R 2 includes a C1-C3 alkyl group or a C1-C3 haloalkyl group. Further optionally, R 2 includes a C1-C2 alkyl group or a C1-C2 haloalkyl group.

[0275] In the above embodiments, the haloalkyl group includes one or more of a fluoroalkyl group, a chloroalkyl group, a bromoalkyl group and an iodoalkyl group. Optionally, the haloalkyl group includes a fluoroalkyl group.

[0276] Exemplarily, the chain carboxylic acid ester solvent includes one or more of the compounds represented by Formula I-1 to Formula I-8,

[0277] In some embodiments, the electrolyte further contains an additive. The additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that can improve certain battery performance, such as an additive for improving the overcharge performance of the battery, an additive for improving the high-temperature performance of the battery, an additive for improving the low-temperature power performance of the battery, etc.

[0278] In some embodiments, the additive includes one or more of a carbonate additive and a sulfur-containing additive, and can be selected as at least two. The above additives can improve the interfacial film performance on the positive electrode side and / or the negative electrode side, which is beneficial to improving the fast charging performance of the battery monomer and improving the cycle performance.

[0279] In some embodiments, the mass content of the additive in the electrolyte is from 0.5% to 6%. Exemplarily, the mass content of the additive 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 composed of any two of the above values.

[0280] The above-mentioned organic solvents, such as chain carboxylic acid ester solvents, may decompose to produce acid at high temperatures, corroding the interfacial film on the surface of the negative electrode. The additive can form a dense and uniform-thickness film layer on the negative electrode side, effectively repair the interfacial film, provide excellent protection for the negative electrode active material, be beneficial to improving the fast charging performance of the battery cell, and improving the cycle performance.

[0281] Exemplarily, the carbonate additives include one or more of vinylene carbonate VC and fluoroethylene carbonate FEC. Optionally, the carbonate additives include vinylene carbonate VC and fluoroethylene carbonate FEC.

[0282] Exemplarily, the sulfur-containing additives include one or more of ethylene sulfate DTD, bis(ethylene sulfate) 2-DTD, butene sulfite BS, 1,3-propane sultone PS, ethylene sulfite ES, and methylene methanedisulfonate MMDS, and may be optionally 1,3-propane sultone PS.

[0283] Exemplarily, the additive includes one or more of vinylene carbonate, fluoroethylene carbonate, and 1,3-propane sultone.

[0284] Optionally, the mass content of vinylene carbonate VC in the electrolyte is from 0.5% to 3.0%, such as 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 a range composed of any two of the above values.

[0285] Optionally, the mass content of fluoroethylene carbonate FEC in the electrolyte is from 0.2% to 2.5%, such as 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 a range composed of any two of the above values.

[0286] Optionally, the mass content of 1,3 - propane sultone PS in the electrolyte is 0.5% to 2.5%, such as 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 the range composed of any two of the above values.

[0287] In the embodiments of the present application, the types and contents of the inorganic components / lithium salts in the electrolyte have the meanings well - known in the art, and can be detected by the equipment and methods well - known in the art. For example, reference can be made to the standard JY / T020 - 1996 "General Rules for Ion Chromatography Analysis Methods" to qualitatively or quantitatively analyze the inorganic components / lithium salts in the electrolyte by ion chromatography analysis method. In the embodiments of the present application, freshly prepared electrolyte can be taken as a sample, the free electrolyte of a fresh battery can be taken as a sample, or a battery that has been fully discharged (discharged to the lower cut - off voltage so that the charged state of the battery is about 0% SOC) can be disassembled in reverse, and the free electrolyte obtained from the battery can be taken as a sample for detection by ion chromatography analysis method.

[0288] In the embodiments of the present application, the types and contents of the organic components in the electrolyte have the meanings well - known in the art, and can be detected by the equipment and methods well - known in the art. For example, reference can be made to GB / T9722 - 2006 "General Rules for Gas Chromatography of Chemical Reagents" to qualitatively and quantitatively analyze the organic components in the electrolyte by gas chromatography.

[0289] In the embodiments of the present application, after quantitatively and qualitatively detecting each component in the electrolyte, each component is classified. Chain - like carboxylic acid ester solvents and carbonate solvents (such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate) are used as the constituent components of the organic solvent. Based on the mass of the electrolyte being 100%, the mass content of each component is calculated. Carbonate additives (such as vinylene carbonate, fluoroethylene carbonate) and sulfur - containing additives are used as additives in the electrolyte. Based on the mass of the electrolyte being 100%, the mass content of each component is calculated.

[0290] In the embodiments of the present application, after quantitatively and qualitatively detecting each component in the electrolyte, each component is classified. Chain - like carboxylic acid ester solvents and carbonate solvents (such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate) are used as the constituent components of the organic solvent. Based on the mass of the electrolyte being 100%, the mass content of each component is calculated. Carbonate additives (such as vinylene carbonate, fluoroethylene carbonate) and sulfur - containing additives are used as additives in the electrolyte. Based on the mass of the electrolyte being 100%, the mass content of each component is calculated.

[0291] Positive electrode plate To more clearly illustrate the present application, the coating portion of the positive electrode tab corresponds to the positive electrode coating portion, the tab ear corresponds to the positive electrode tab ear, the active material layer corresponds to the positive electrode film layer containing the positive electrode active material, and the positive electrode coating portion includes a positive electrode current collector portion and a positive electrode film layer provided on at least one side of the positive electrode current collector portion.

[0292] The positive electrode tab includes a positive electrode current collector portion and a positive electrode film layer provided on at least one surface of the positive electrode current collector portion and including the positive electrode active material. For example, the positive electrode current collector portion has two surfaces opposite to each other in its own thickness direction, and the positive electrode film layer is provided on any one or both of the two opposite surfaces of the positive electrode current collector portion.

[0293] The upper charge limit voltage and the discharge cut-off voltage of the battery cell vary depending on the positive electrode active material. For example, when the phosphate material includes lithium iron phosphate, the upper charge limit voltage can be 3.65 V and the discharge cut-off voltage can be 2.0 V, or the upper charge limit voltage can be 3.8 V and the discharge cut-off voltage can be 2.0 V; for another example, when the phosphate material includes lithium manganese iron phosphate, the upper charge limit voltage can be 4.3 V and the discharge cut-off voltage can be 2.0 V. Next, taking the upper charge limit voltage of 3.65 V and the discharge cut-off voltage of 2.0 V as an example, the state of the battery cell will be described: In the embodiment of the present application, the 100% state of charge (SOC) and the 0% state of charge (SOC) of the battery cell are defined as follows. The battery cell is charged at a constant current charge rate of 0.33 C to the upper charge limit voltage and then charged at a constant voltage to 0.05 C, corresponding to the state of 100% SOC of the battery cell. The battery cell is discharged at a constant current discharge rate of 0.33 C to the cut-off voltage, corresponding to the state of 0% SOC of the battery cell.

[0294] In some embodiments, when the battery cell is in the 0% state of charge (SOC), the compaction density of the positive electrode film layer is 2.30 g / cm 3 to 2.70 g / cm 3 ; it can be optionally 2.40 g / cm 3 to 2.55 g / cm 3 . Exemplarily, when the battery cell is in the 0% state of charge (SOC), the compaction density of the positive electrode film layer is 2.30 g / cm 3 , 2.32 g / cm 3 , 2.35 g / cm 3 , 2.38 g / cm 3 , 2.40 g / cm 3 , 2.42 g / cm 3 , 2.45 g / cm 3 , 2.48 g / cm3 , 2.50 g / cm 3 , 2.52 g / cm 3 , 2.55 g / cm 3 , 2.56 g / cm 3 , 2.57 g / cm 3 , 2.58 g / cm 3 , 2.60 g / cm 3 , 2.62 g / cm 3 , 2.65 g / cm 3 , 2.68 g / cm 3 , 2.70 g / cm 3 or a range composed of any two of the above values.

[0295] When the compaction density of the positive electrode film layer is within the above range, it is beneficial to improve the single-cell energy of the battery cell and increase the energy density; and because the positive electrode active material in the positive electrode film layer is stacked relatively tightly and the contact resistance between particles is small, the resistance of the electrode sheet can be further reduced, thereby reducing the heat generation during fast charging and improving the fast charging ability of the battery cell.

[0296] In some embodiments, the single-sided coating weight of the positive electrode film layer is 250 mg / 1540.25 mm 2 to 330 mg / 1540.25 mm 2 , and can be optionally 275 mg / 1540.25 mm 2 to 300 mg / 1540.25 mm 2 . Exemplarily, the single-sided coating weight of the positive electrode film layer is 250 mg / 1540.25 mm 2 , 260 mg / 1540.25 mm 2 , 270 mg / 1540.25 mm 2 , 280 mg / 1540.25 mm 2 , 290 mg / 1540.25 mm 2 , 300 mg / 1540.25 mm 2 , 310 mg / 1540.25 mm 2 , 320 mg / 1540.25 mm 2 , 330 mg / 1540.25 mm 2 or a range composed of any two of the above values.

[0297] When the single-sided coating weight of the positive electrode film layer is within the above range, it is beneficial to improve the single-cell energy of the battery cell and increase the energy density; the heat generation per unit area of the positive electrode sheet will not be too large, and the fast charging ability of the battery cell can be improved.

[0298] In the embodiments of the present application, the tap density of the positive electrode film layer of the battery cell at 0% state of charge (SOC) has the meaning well-known in the art, that is, the positive electrode plate is disassembled from the battery cell at 0% SOC, and the tap density of the positive electrode film layer is measured. For example, for a single-sided coated positive electrode plate (if it is a double-sided coated plate, the positive electrode film layer on one side can be wiped off first), it is punched into small round pieces with an area of S1, weighed, recorded as M1, and its thickness H1 is measured. Then, the positive electrode film layer of the above-mentioned weighed positive electrode plate is wiped off, and the weight of the positive electrode current collector is weighed and recorded as M0, and its thickness H0 is measured. The single-sided coating weight of the positive electrode film layer = (the weight M1 of the positive electrode plate - the weight M0 of the positive electrode current collector) / S1, the thickness of the positive electrode film layer = the thickness H1 of the positive electrode plate - the thickness H0 of the positive electrode current collector, and the tap density of the positive electrode film layer = the single-sided coating weight of the positive electrode film layer / the thickness of the positive electrode film layer.

[0299] In some embodiments, the positive electrode active material includes lithium-containing phosphate with an olivine structure. In other embodiments, the positive electrode active material may also include lithium-containing transition metal oxides, etc. Examples of lithium-containing transition metal oxides may 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.

[0300] In the embodiments of the present application, the lithium-containing phosphate with an olivine structure can be phosphate particles or a material obtained by coating and modifying them. For example, the lithium-containing phosphate with an olivine structure includes phosphate particles and a coating layer, and 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, is beneficial to the migration rate of lithium ions, improves the fast charging ability of the battery, and reduces the heat generation of the battery cell.

[0301] In some embodiments, the phosphate particles include a compound with the general formula Li x1 A y1 Me a M b P 1-c X c Y z where 0.5 ≤ x 1 ≤ 1.3, 0 ≤ y 1 ≤ 1.3, and 0.9 ≤ x 1 + y 1≤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. The phosphate particles have excellent cycle stability, which is beneficial to improving the cycle performance of the battery cell.

[0302] Exemplarily, the phosphate particles include LiFePO 4 , LiMnPO 4 , LiNiPO 4 , LiCoPO 4 or one or more thereof. During the charge and discharge process of the battery cell, the insertion and extraction and consumption of active ions such as Li will occur, and the molar content of Li is different when the battery cell is discharged to different states. Regarding the positive electrode active materials LiFePO 4 , LiMnPO 4 , LiNiPO 4 , LiCoPO 4 etc., the molar content of Li is the initial state of the material, that is, the state before feeding. When the positive electrode active material is applied to the battery system and undergoes charge and discharge cycles, the molar content of Li may change. In the embodiments of the present application, regarding the positive electrode active materials LiFePO 4 , LiMnPO 4 , LiNiPO 4 , LiCoPO 4 etc., the molar content of oxygen O is only the theoretical state value. The release of oxygen from the lattice will cause the molar content of oxygen O to change. Actually, the molar content of oxygen O will show fluctuations, and the above situations are all within the protection scope of the present application.

[0303] In the embodiments of the present application, the content of elements in the positive electrode active material has the meaning well-known in the art and can be detected by devices and methods well-known in the art. For example, referring to EPA 6010D-2014, it is tested by inductively coupled plasma atomic emission spectrometry, and determined by inductively coupled plasma optical emission spectrometry (ICP-OES, instrument model: Thermo ICAP7400). After discharging the battery cell to 0% state of charge (SOC) and disassembling the positive electrode plate, it is cleaned with dimethyl carbonate (DMC) and dried, and then after high-temperature calcination to remove impurities, 0.4 g of the positive electrode active material is weighed, and 10 ml (50% concentration) of aqua regia is added thereto. Then it is placed on a flat plate at 180 °C for 30 min. After digestion on the flat plate, it is fixed to a volume of 100 mL, and quantitative testing is carried out by the standard curve method.

[0304] In some embodiments, the positive electrode film layer further includes a positive electrode additive. The positive electrode additive may include lithium element and can release lithium ions during the charging process of the battery cell to make up for lithium loss, which is beneficial to improving the capacity characteristics and cycling performance of the battery cell.

[0305] In some embodiments, the positive electrode additive includes at least one of lithium ferrite particles or lithium nickelate particles.

[0306] In some embodiments, the average longest diameter of the positive electrode additive is 2 μm to 5 μm, such as 2 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm or the range composed of any two of them.

[0307] In the embodiments of the present application, the positive electrode plate is cut along the thickness direction of the plate to expose the longitudinal section of the positive electrode film layer; by performing scanning electron microscopy (SEM) testing on the longitudinal section of the positive electrode film layer, the longest diameter and the shortest diameter of the positive electrode additive particles and the longest diameter of the lithium-containing phosphate are determined. For example, the "longest diameter" of the particle refers to the longest straight line passing through the center point of the particle and extending to the outer periphery of the particle; In the cross-section of the positive electrode film layer along its own thickness direction, the longest diameters of multiple, for example, 10 iron oxides containing lithium are counted, and the average value thereof is calculated as the average longest diameter.

[0308] In some embodiments, based on the total mass of the positive electrode film layer, the mass content of the positive electrode additive is 0.2% to 2%, such as 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0% or the range composed of any two of them. When using the positive electrode additive within the mass range, lithium can be effectively supplemented.

[0309] In some embodiments, the positive electrode film layer may further optionally include a positive electrode conductive agent. There is no particular limitation on the type of the positive electrode conductive agent in the embodiments of the present application. By way of example, the positive electrode conductive agent includes 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, based on the mass of the positive electrode film layer, the mass content of the positive electrode conductive agent is ≤5%.

[0310] In some embodiments, the positive electrode film layer may further optionally include a positive electrode binder. There is no particular limitation on the type of the positive electrode binder in the embodiments of the present application. By way of example, the positive electrode binder may include at least one of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and fluorinated acrylate resins. In some embodiments, based on the mass of the positive electrode film layer, the mass content of the positive electrode binder is ≤5%.

[0311] In some embodiments, the positive electrode current collector portion may employ a metal foil or a composite current collector. By way of example of the metal foil, at least one foil of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. By way of example, the metal material of the metal material layer may include at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. By way of example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0312] In some embodiments, the ratio of the thickness of the single-sided positive electrode film layer to the thickness of the positive electrode current collector portion is 3 to 10, such as 3, 4, 5, 6, 7, 8, 9, 10 or a range composed of any two of the above values. Optionally, the ratio of the thickness of the single-sided positive electrode film layer to the thickness of the positive electrode current collector portion is 4 to 8.

[0313] When the ratio of the thickness of the single-sided positive electrode film layer to the thickness of the positive electrode current collector portion is within the above range, the fast charging ability and energy density of the battery cell can be improved.

[0314] In some embodiments, the thickness of the positive electrode current collector portion is 12 μm to 16 μm, and may be optionally 13 μm to 15 μm. Exemplarily, the thickness of the positive electrode current collector portion 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 composed of any two of the above values.

[0315] When the thickness of the positive current collector portion is within the above range, the overcurrent capacity of the positive current collector portion is relatively excellent, and the battery cell can have a high energy density.

[0316] In the embodiments of the present application, the thicknesses of the positive electrode film layer and the positive current collector portion have meanings well-known in the art, and can be detected by equipment and methods well-known in the art. For example, the thickness of the positive electrode sheet is measured with a micrometer, the film layer on the surface of the positive current collector portion is removed, and the thickness of the positive current collector portion is measured with a micrometer. When the positive electrode film layer is coated on one side, the thickness of the positive electrode film layer is the thickness of the positive electrode sheet minus the thickness of the positive current collector portion. When the positive electrode film layer is coated on both sides, the thickness of the positive electrode film layer is (the thickness of the positive electrode sheet minus the thickness of the positive current collector portion) / 2.

[0317] The positive electrode film layer is usually formed by coating a positive electrode slurry on the positive current collector portion and then drying and cold pressing. The positive electrode slurry is usually formed by dispersing a positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent and stirring evenly. The solvent can be N-methylpyrrolidone (NMP), but is not limited thereto.

[0318] The positive electrode sheet does not exclude other additional functional layers besides the positive electrode film layer. For example, in some embodiments, the positive electrode sheet of the embodiments of the present application further includes a positive electrode conductive layer sandwiched between the positive current collector portion and the positive electrode film layer and disposed on the surface of the positive current collector portion. In some other embodiments, the positive electrode sheet of the embodiments of the present application further includes a protective layer covering the surface of the positive electrode film layer.

[0319] Negative electrode plate To illustrate the present application more clearly, the coated portion of the negative electrode sheet corresponds to the negative electrode coated portion, the tab portion corresponds to the negative electrode tab, the active material layer corresponds to the negative electrode film layer containing the negative electrode active material, and the negative electrode coated portion includes a negative current collector portion and a negative electrode film layer disposed on at least one side of the negative current collector portion. The negative electrode coated portion includes a negative current collector portion and a negative electrode film layer disposed on at least one side of the negative current collector portion.

[0320] The negative electrode sheet includes a negative current collector portion and a negative electrode film layer disposed on at least one surface of the negative current collector portion and including a negative electrode active material. For example, the negative current collector portion has two surfaces opposite to each other in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative current collector portion.

[0321] In some embodiments, when the battery cell is at 0% state of charge (SOC), the compaction density of the negative electrode film layer is 1.30 g / cm 3 to 1.65 g / cm 3 ; optionally 1.35 g / cm 3 to 1.50 g / cm 3. Exemplarily, the compaction density of the negative electrode film layer at 0% state of charge of the battery cell is 1.3 g / cm 3 、1.32 g / cm 3 、1.35 g / cm 3 、1.40 g / cm 3 、1.45 g / cm 3 、1.50 g / cm 3 、1.55 g / cm 3 、1.60 g / cm 3 、1.65 g / cm 3 or a range composed of any two of the above values.

[0322] When the compaction density of the negative electrode film layer is within the above range, it is beneficial to improve the energy of the battery cell and the energy density; and because the negative electrode active material of the negative electrode film layer is stacked relatively tightly and the contact resistance between particles is small, the resistance of the electrode sheet can be further reduced, thereby reducing heat generation and improving the fast charging performance of the battery cell.

[0323] In the embodiments of the present application, the compaction density of the negative electrode film layer at 0% state of charge (SOC) of the battery cell has the meaning well-known in the art, and can be detected by equipment and methods well-known in the art. The detection method is the same as the compaction density test method of the positive electrode film layer described above.

[0324] In some embodiments, the single-sided coating weight of the negative electrode film layer is 120 mg / 1540.25 mm 2 to 180 mg / 1540.25 mm 2 , and can be optionally 125 mg / 1540.25 mm 2 to 150 mg / 1540.25 mm 2 . Exemplarily, the single-sided coating weight of the negative electrode film layer is 120 mg / 1540.25 mm 2 、122 mg / 1540.25 mm 2 、125 mg / 1540.25 mm 2 、128 mg / 1540.25 mm 2 、130 mg / 1540.25 mm 2 、132 mg / 1540.25 mm 2 、135 mg / 1540.25 mm 2 、137 mg / 1540.25 mm 2 、140 mg / 1540.25 mm 2 、145 mg / 1540.25 mm 2 、150 mg / 1540.25 mm 2 、155 mg / 1540.25 mm2 、160 mg / 1540.25 mm 2 、165 mg / 1540.25 mm 2 、170 mg / 1540.25 mm 2 、175 mg / 1540.25 mm 2 、180 mg / 1540.25 mm 2 or a range composed of any two of the above values.

[0325] When the single-sided coating weight of the negative electrode film layer is within the above range, it is beneficial to improve the single-cell energy of the battery cell and the energy density; moreover, the heat generation per unit area of the negative electrode plate will not be too large, and the fast charging ability of the battery cell can be improved.

[0326] In the embodiments of the present application, the single-sided coating weight of the negative electrode film layer has the meaning well-known in the art, and can be detected by using the equipment and methods well-known in the art. The detection method is as described in the single-sided coating weight test method of the film layer above.

[0327] In some embodiments, the negative electrode active material includes a carbon-based material. The carbon-based material has relatively high cycle stability and can improve the cycle performance of the battery cell. The positive electrode active material of the present application is mainly a lithium-containing phosphate system with an olivine structure, and the negative electrode active material is mainly a carbon-based material system. When the two are used in combination, the cycle performance of the battery cell is relatively excellent.

[0328] Optionally, the carbon-based material includes artificial graphite, and the graphitization degree of the artificial graphite is from 90% to 95%, and can be optionally from 92% to 95%. Exemplarily, the graphitization degree of the artificial graphite is 90%, 90.5%, 91%, 91.5%, 92.0%, 92.5%, 93%, 93.5%, 94%, 94.5%, 95% or a range composed of any two of the above values.

[0329] When the graphitization degree of the artificial graphite is within the above range, the artificial graphite has relatively excellent electrical conductivity, can reduce the heat generation of the negative electrode plate and the heat generation of the battery cell, and can improve the fast charging performance of the battery cell.

[0330] In some embodiments, the carbon-based material may further include natural graphite. Specifically, the carbon-based material may include artificial graphite, or the carbon-based material may include artificial graphite and natural graphite.

[0331] In some embodiments, in addition to the above-mentioned carbon-based material and optional silicon-based material, the negative electrode active material may further include at least one of a tin-based material and lithium titanate. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy material. Optionally, the silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material.

[0332] In this application, the qualitative and quantitative analysis of each substance or element can be detected by suitable equipment and methods known to those skilled in the art. Relevant detection methods can refer to domestic and foreign detection standards, domestic and foreign enterprise standards, etc. And those skilled in the art can also adaptively change certain detection steps / instrument parameters from the perspective of detection accuracy to obtain more accurate detection results. One detection method can be used for qualitative or quantitative analysis, or several detection methods can be used in combination for qualitative or quantitative determination.

[0333] For example, this application can combine the general rules of X-ray diffraction analysis method in JIS / K0131-1996 to conduct X-ray powder diffraction testing and qualitative analysis on the negative electrode sheet or negative electrode active material.

[0334] Artificial graphite and natural graphite can be distinguished by the SEM cross-sectional view taken by scanning electron microscope (SEM). There are voids between flaky structures in the SEM cross-sectional view of natural graphite, while the SEM cross-sectional view of artificial graphite is dense and has no obvious gaps. Or they can be distinguished by the XRD spectrum obtained by X-ray diffraction method. There are obvious 2H phase and 3R phase in the XRD spectrum of natural graphite, while only 2H phase exists in the XRD spectrum of artificial graphite.

[0335] In the embodiments of this application, the negative electrode film layer includes at least one layer of film layer, which can be a single-layer film layer or at least two layers of film layers. Optionally, the negative electrode film layer includes at least two layers of film layers.

[0336] When the negative electrode film layer adopts a single-layer film layer, the negative electrode active material in the negative electrode film layer includes carbon-based materials. When adopting a single-layer film layer, the volume average particle size Dv50 of the carbon-based material is 8 μm to 13 μm, and can be 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 the range composed of any two of the above values.

[0337] When the negative electrode film layer adopts at least two layers of film layers, the negative electrode active material in the negative electrode film layer includes carbon-based materials. The negative electrode film layer can include two layers of film layers, three layers of film layers, four layers of film layers, or even more layers of film layers.

[0338] In some embodiments, the negative electrode film 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 portion. The carbon-based material of the first negative electrode film layer includes artificial graphite. The second negative electrode film layer is connected to the side of the first negative electrode film layer facing away from the negative electrode current collector portion. The carbon-based material of the second negative electrode film layer includes artificial graphite. The artificial graphite of the first negative electrode film layer and the artificial graphite of the second negative electrode film layer may be the same or different. When the artificial graphite of the first negative electrode film layer and the artificial graphite of the second negative electrode film layer are different, it may be the particle size that is different or the graphitization degree that is different.

[0339] The interface between the first negative electrode film layer and the second negative electrode film layer may be regular or irregular, and optionally it is irregular.

[0340] The negative electrode film layer includes at least two film layers, and layer-by-layer coating is beneficial to improving the fast charging performance of the battery cell. Especially when there are differences between the first negative electrode film layer and the second negative electrode film layer, it is possible to construct pore differences in the negative electrode film layer, reduce the tortuosity of lithium ion transport, and improve the fast charging performance of the battery cell.

[0341] In some embodiments, the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is greater than or equal to the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer. Further optionally, the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is greater than the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer, which is beneficial to improving the kinetic performance of the negative electrode film layer.

[0342] There are differences in the particle sizes of the first negative electrode film layer and the second negative electrode film layer, which can improve the fast charging performance of the battery cell. Specifically, during the fast charging process, the overpotential of the second negative electrode film layer is usually relatively high, and the bottleneck of fast charging mainly lies in the second negative electrode film layer. In the embodiments of the present application, the particle size of the second negative electrode film layer is relatively small, which can shorten the solid-phase transport path of lithium ions, improve the fast charging performance, and can also improve the problem of lithium deposition on the surface layer of the negative electrode plate.

[0343] Optionally, the carbon-based material of the first negative electrode film layer is granular, and its volume average particle size Dv50 is from 9.0 μm to 18.5 μm, and can be optionally from 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 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 a range composed of any two of the above values. When the first negative electrode film layer includes a carbon-based material, the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is from 9.0 μm to 18.5 μm, and can be optionally from 9.0 μm to 14.6 μm.

[0344] When the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is within the above range, on the one hand, it can shorten the solid-phase transmission path of lithium ions and improve the fast charging performance. On the other hand, the material is not prone to agglomeration during the preparation process, which can improve the stability of the material.

[0345] Optionally, the carbon-based material of the second negative electrode film layer is granular, and its volume average particle size Dv50 is from 7.8 μm to 14.3 μm, and can be optionally from 7.8 μm to 11.3 μm. Exemplarily, 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 composed of any two of the above values. When the second negative electrode film layer includes a carbon-based material, the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer is from 7.8 μm to 14.3 μm, and can be optionally from 7.8 μm to 11.3 μm.

[0346] When the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer is within the above range, it can shorten the solid-phase transmission path of lithium ions and improve the fast charging performance.

[0347] When the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer is within the above range, on the one hand, it can shorten the solid-phase transmission path of lithium ions and improve the fast charging performance. On the other hand, the material is not prone to agglomeration during the preparation process, which can improve the stability of the material. On the other hand, the negative electrode active material in the second negative electrode film layer and the negative electrode active material in the first negative electrode film layer cooperate within the above volume average particle size range, which is beneficial to constructing the gradient pore difference between the second negative electrode film layer and the first negative electrode film layer, reducing the tortuosity of lithium ion transmission, and improving the fast charging performance of the battery cell.

[0348] In the embodiments of the present application, the volume average particle size Dv50 of the negative electrode active material has the meaning well known in the art, and can be detected by using the equipment and methods well known in the art. For example, taking the negative electrode active material as a sample, according to the test standard GB / T 19077-2016, the Dv50 and Dv10 of the particles are tested by a Mastersizer 2000E laser particle size analyzer.

[0349] Optionally, the carbon-based material of the first negative electrode film layer further includes natural graphite.

[0350] Exemplarily, the carbon-based material of the first negative electrode film layer includes at least one of artificial graphite and natural graphite, and the carbon-based material of the second negative electrode film layer includes artificial graphite.

[0351] In some other embodiments, the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer is greater than the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer. Further optionally, the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer being greater than the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is beneficial to improving the compaction density of the negative electrode film layer.

[0352] The difference in the particle sizes of the first negative electrode film layer and the second negative electrode film layer can improve the fast charging performance of the battery cell.

[0353] Optionally, the carbon-based material of the second negative electrode film layer is granular, and its volume average particle size Dv50 is from 9.0 μm to 18.5 μm, and can be optionally from 9.0 μm to 14.6 μm. When the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer is within the above range, on the one hand, it can shorten the solid-phase transmission path of lithium ions and improve the fast charging performance. On the other hand, the material is not prone to agglomeration during the preparation process, which can improve the stability of the material.

[0354] Optionally, the carbon-based material of the first negative electrode film layer is granular, and its volume average particle size Dv50 is 7.8 μm to 14.3 μm, and may be optionally 7.8 μm to 11.3 μm. When the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is within the above range, the solid-phase transmission path of lithium ions can be shortened, and the fast charging performance can be improved.

[0355] Exemplarily, the carbon-based material of the second negative electrode film layer includes at least one of artificial graphite and natural graphite, and the carbon-based material of the first negative electrode film layer includes artificial graphite.

[0356] In some embodiments, the negative electrode film layer may further optionally include a negative electrode conductive agent. There is no particular limitation on the type of the negative electrode conductive agent in the embodiments of the present application. 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, based on the total weight of the negative electrode film layer, the mass content of the negative electrode conductive agent is ≤5%.

[0357] In some embodiments, the negative electrode film layer may further optionally include a negative electrode binder. In some embodiments, based on the total weight of the negative electrode film layer, the mass content of the negative electrode binder is ≤5%.

[0358] In some embodiments, the negative electrode film layer may further optionally include other additives. As an example, the other additives may include a thickener, a dispersant, etc., for example, sodium carboxymethyl cellulose (CMC-Na), PTC thermistor materials, etc. In some embodiments, based on the total weight of the negative electrode film layer, the mass content of the other additives is ≤2%.

[0359] In some embodiments, the negative electrode current collector portion may be a metal foil or a composite current collector portion. As an example of the metal foil, at least one foil of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy may be used. The composite current collector portion may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material in the metal material layer may include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0360] In some embodiments, the ratio of the thickness of the single-sided negative electrode film layer to the thickness of the negative electrode current collector portion is 8 to 14, such as 8, 9, 10, 11, 12, 13, 14 or the range composed of any two of the above values. Optionally, the ratio of the thickness of the single-sided negative electrode film layer to the thickness of the negative electrode current collector portion is 10 to 12.

[0361] When the ratio of the thickness of the single-sided negative electrode film layer to the thickness of the negative electrode current collector is within the above range, the rapid charging ability and energy density of the battery cell can be improved.

[0362] In some embodiments, the thickness of the negative electrode current collector is 5 μm to 10 μm, and can be optionally 6 μm to 8 μm. Exemplarily, the thickness of the negative electrode 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 the range composed of any two of the above values.

[0363] 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 relatively excellent, and the battery cell can have a high energy density.

[0364] In the embodiments of the present application, the thickness of the negative electrode current collector has the meaning well-known in the art, and can be detected by using the equipment and methods well-known in the art. For example, the film layer on the surface of the negative electrode current collector is washed away with a solvent, and the thickness of the negative electrode current collector is measured with a micrometer.

[0365] The negative electrode film layer is usually formed by coating a negative electrode slurry on the negative electrode current collector and then drying and cold pressing. The negative electrode slurry is usually formed by dispersing negative electrode active materials, optional conductive agents, optional binders, and other optional additives in a solvent and stirring evenly. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.

[0366] The negative electrode plate does not exclude other additional functional layers except the negative electrode film layer. For example, in some embodiments, the negative electrode plate of the embodiments of the present application further includes a negative electrode conductive layer sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. In other embodiments, the negative electrode plate of the embodiments of the present application further includes a protective layer covering the surface of the negative electrode film layer.

[0367] [Separator] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode plate and the negative electrode plate.

[0368] In some embodiments, the separator is a separator film. The present application does not particularly limit the type of the separator film, and any well-known porous structure separator film with good chemical stability and mechanical stability can be selected.

[0369] 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, without particular limitation. The separator can be a single component located between the positive and negative electrodes, or can be attached to the surfaces of the positive and negative electrodes. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be coated on the surface of the separator.

[0370] In some embodiments, the volumetric energy density of the battery cell is from 385 Wh / L to 450 Wh / L. Exemplarily, the volumetric energy density of the battery cell is 385 Wh / L, 390 Wh / L, 400 Wh / L, 410 Wh / L, 420 Wh / L, 430 Wh / L, 450 Wh / L or a range composed of any two of the above values. The volumetric energy density of the battery cell is relatively high.

[0371] In the embodiments of the present application, the volumetric energy density of the battery cell has the meaning well-known in the art, and can be detected by using the equipment and methods well-known in the art. For example, taking the upper limit voltage of battery charging as 3.65 V and the cut-off voltage of battery discharging as 2.0 V as an example for illustration, The battery cell is placed at 25 °C, charged at a constant current of 0.33 C to 3.65 V, then charged at a constant voltage to 0.05 C, and discharged at a constant current of 0.33 C to 2.0 V. Record the discharge capacity A0 at this time, unit: Ah. Use a caliper to measure the length, width, and height of the battery cell (generally calculated based on the outer shell size of the battery, excluding the height of the electrode terminals and excluding the insulating film outside the outer shell), calculate the volume V0 of the single battery cell, unit: L. The volumetric energy density VED of the battery cell = (A0 × discharge platform voltage) / V0, unit: Wh / L.

[0372] In some embodiments, the volumetric energy density of the battery cell can be adjusted by the following optional methods: From the perspective of the active material, positive and negative electrode active materials with high specific capacity can be used. For example, for the positive electrode active material, a lithium-containing phosphate material with a higher gram capacity is used. For example, physically mix positive electrode active materials with a higher gram capacity, such as ternary materials, to improve the energy density; for example, for the negative electrode active material, graphite with a higher gram capacity is used. For example, physically mix negative electrode active materials with a higher gram capacity, such as silicon-based materials, etc.; From the perspective of the electrolyte, reduce the injection amount of the electrolyte, or use an electrolyte that supports a higher energy density, etc.; From the perspective of the electrode design, the compaction density and coating weight of the positive electrode or negative electrode can be adjusted, or the thickness of the positive current collector or negative current collector can be adjusted, etc.; In terms of the separator membrane, the thickness of the separator membrane can be adjusted, etc.; In terms of structural design, first, the proportion of non-active substances such as battery components can be reduced. For example, making the battery casing thinner while ensuring its safety and mechanical properties, so that more active substances can be accommodated in the same space, improving the energy density. For example, adjusting the space proportion of the electrode assembly in the housing cavity of the casing.

[0373] Embodiment The following embodiments more specifically describe the content disclosed in the embodiments of the present application. These embodiments are only for illustrative purposes, because various modifications and changes within the scope of the content disclosed in the embodiments of the present application are obvious to those skilled in the art. 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 according to conventional methods and can be used directly without further treatment, and all instruments used in the embodiments are commercially available.

[0374] Example 1 1. Preparation of the positive electrode sheet The positive electrode sheet includes a positive current collector part and positive electrode film layers arranged on both sides of the positive current collector part. The positive current collector part is an aluminum foil with a thickness of 13.5 μm.

[0375] The positive electrode film layer includes a lithium-containing phosphate, a binder polyvinylidene fluoride (PVDF), and a conductive agent acetylene black with a mass ratio of 96:2:2. The positive electrode film layer is a film layer formed by uniformly coating the positive electrode slurry (the solvent is N-methylpyrrolidone NMP) on both sides of the positive current collector part and then drying and cold pressing.

[0376] The lithium-containing phosphate includes lithium iron phosphate.

[0377] The single-sided coating weight of the positive electrode film layer is 300 mg / 1540.25 mm 2 .

[0378] The length of the positive electrode film layer is 500 mm, and the ratio of the length to the width of the positive electrode film layer is 5.25.

[0379] 2. Preparation of the negative electrode sheet The negative electrode sheet includes a negative current collector part and negative electrode film layers arranged on both sides of the negative current collector part. The negative current collector part is a copper foil with a thickness of 6 μm.

[0380] The negative electrode film layer is a film layer formed by uniformly coating the negative electrode slurry (the solvent is deionized water) on the surface of the negative current collector part and then drying and cold pressing.

[0381] The single-sided coating weight of the negative electrode film layer is 130 mg / 1540.25 mm2 .

[0382] The negative electrode film 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 part, and the second negative electrode film layer is located on the surface of the first negative electrode film layer.

[0383] The first negative electrode film layer includes a carbon-based material, conductive agent acetylene black, negative electrode binder styrene-butadiene rubber, and thickening agent sodium carboxymethyl cellulose with 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 with a mass ratio of 1:1, and the volume average particle size of the carbon-based material is 9.0 μm.

[0384] The second negative electrode film layer includes a carbon-based material, conductive agent acetylene black, negative electrode binder styrene-butadiene rubber, and thickening agent sodium carboxymethyl cellulose with a mass ratio of 96.5:1:1.5:1. The carbon-based material of the second negative electrode film layer includes artificial graphite, and the volume average particle size of the carbon-based material is 8.0 μm.

[0385] 3. Separator The separator includes a base film, which is a 7-μm polyethylene film layer with a porosity of 42%.

[0386] 4. Preparation of electrolyte The electrolyte includes an organic solvent, a lithium salt, and an additive.

[0387] The organic solvent includes 10% chain carboxylic acid ester solvent (ethyl acetate) and 75% carbonate solvent (diethyl carbonate, dimethyl carbonate, ethylene carbonate with a mass ratio of 1:1:1). The mass content of each component in the organic solvent is calculated based on the mass of the electrolyte.

[0388] Based on the mass of the electrolyte, the mass content of the additive is 1.5%, which includes vinylene carbonate VC.

[0389] The lithium salt includes 8.5% lithium hexafluorophosphate LiPF 6 and 5% lithium bis(fluorosulfonyl)imide.

[0390] The conductivity of the electrolyte at room temperature is 12 mS / cm.

[0391] 5. Preparation of battery cell Stack the above positive electrode plate, separator, and negative electrode plate in sequence, with the separator between the positive electrode plate and the negative electrode plate to play an isolation role, obtaining a stacked electrode assembly. Place the electrode assembly in the outer shell assembly, inject the electrolyte after drying, and obtain the battery cell through processes such as vacuum packaging, standing, formation, and shaping. The compaction density of the positive electrode film layer of the battery cell at 0% SOC is 2.5 g / cm 3 , and the compaction density of the negative electrode film layer at 0% SOC is 1.45 g / cm 3, The outer shell assembly further includes a housing, an end cap, a positive terminal, and a negative terminal. The housing accommodates an electrode assembly and an electrolyte. The housing includes an opening, and the end cap covers the opening. The positive terminal and the negative terminal are disposed on the end cap; The length of the battery cell is 525 mm, the thickness of the battery cell is 10 mm, the width is 100 mm, and the ratio of the length to the thickness is 52.5.

[0392] Comparative Examples 1 to 3 The battery cells were prepared by a method similar to that of Example 1. Different from Example 1, the minimum cross-sectional areas of the positive terminal and the negative terminal were adjusted, and the parameters are shown in Table 1.

[0393] Among them, in Comparative Examples 1 and 2, the dimensions of the battery cells were also adjusted. The ratio of the length to the width of the positive electrode plate in Comparative Example 1 was 2; the length of the battery cell was 225 mm, the thickness of the battery cell was 10 mm, the width was 100 mm, and the ratio of the length to the thickness was 22.5.

[0394] The ratio of the length to the width of the positive electrode plate in Comparative Example 2 was 8; the length of the battery cell was 825 mm, the thickness of the battery cell was 10 mm, the width was 100 mm, and the ratio of the length to the thickness was 82.5.

[0395] Examples 2-1 to 2-3 The battery cells were prepared by a method similar to that of Example 1. Different from Example 1, the minimum cross-sectional areas of the positive terminal and the negative terminal were adjusted, and the parameters are shown in Table 1.

[0396] Example 3 The battery cells were prepared by a method similar to that of Example 1. Different from Example 1, the number of the positive terminal and the negative terminal was adjusted, and the parameters are shown in Table 1.

[0397] Examples 4-1 and 4-2 The battery cells were prepared by a method similar to that of Example 1. Different from Example 1, the welding mark area of the positive terminal and the positive electrode tab was adjusted, and the parameters are shown in Table 1.

[0398] Table 1

[0399] In Table 1, x 1 represents the number of positive terminals; x 2 represents the number of negative terminals; S 1 represents the minimum cross-sectional area of a single positive terminal perpendicular to its own thickness direction, and its unit is mm2 ; S 2 represents the minimum cross-sectional area of a single negative terminal perpendicular to its own thickness direction, with the unit of mm 2 ; M 1 represents the welding mark area of all positive terminals with the positive electrode tab, with the unit of mm 2 ; M 2 represents the welding mark area of all negative terminals with the negative electrode tab, with the unit of mm 2 ; In Example 1, the dimension T of the first protruding portion of the positive terminal 1 is 2 mm, and the dimension T of the second protruding portion of the negative terminal is 2 mm. As Figure 9 shown, the two positive terminals are respectively arranged on both sides of the electrode assembly along the length direction of the battery cell, and the two negative terminals are respectively arranged on both sides of the electrode assembly along the length direction of the battery cell.

[0400] Except for Example 3, other examples and comparative examples adopt the same arrangement of electrode terminals as in Example 1.

[0401] In Example 3, as Figure 11 shown, there is one positive terminal, which is arranged on one side of the electrode assembly along the length direction of the battery cell, and there is one negative terminal, which is respectively arranged on the other side of the electrode assembly along the length direction of the battery cell.

[0402] Performance test 1. DC internal resistance DCR test of the battery cell The method in GB / T 31467 "Performance Test Specification for High-Power Lithium-Ion Power Batteries for HEV" can be referred to.

[0403] For example, at 25 °C, the battery cell is charged to 3.65 V with a constant current of 0.33 C, left standing for 1 min, then charged to 3.65 V with a constant current of 0.05 C, left standing for 30 min, and discharged to 2.5 V with a constant current of 0.33 C, and the discharge capacity A 0 is recorded, with the unit of Ah, and then charged with a constant current of 0.33 C for 0.5 A 0 Ah to adjust the SOC to 50%.

[0404] After the battery cell is placed at 25 °C and left standing for 2 h, it is discharged with a constant current of 4 C for 10 s, and ∆U 放电 , ∆I 放电 are recorded, and the discharge DCR data of the lithium-ion battery is calculated through the following formula, R 放电 = ∆U 放电 / ∆I放电 , Among them, ∆U 放电 represents the voltage change within 10 s after the start of discharge, and ∆I 放电 represents the current value within 10 s after the start of discharge.

[0405] The test results are shown in Table 2.

[0406] Table 2

[0407] In Table 2, E represents the single-cell energy of the battery cell, and its unit is Wh. The single-cell energy E of each example and comparative example is 225 Wh.

[0408] In Comparative Example 1 and Comparative Example 3, the over-current area of the electrode terminal is relatively small, resulting in insufficient over-current capacity, which causes a relatively large internal resistance of the battery cell and is not conducive to fast charging at high energy density.

[0409] In Comparative Example 2, although the over-current capacity of the electrode terminal is strong, the ratio of the length to the width of the positive electrode plate in Comparative Example 2 is too large, and the length of the battery cell is relatively large, resulting in a relatively long migration path of electrons in the length direction of the positive electrode plate and a relatively large internal resistance, which is not conducive to fast charging at high energy density.

[0410] In the embodiments of the present application, by adjusting the over-current area of the electrode terminal, such that (x 1 ×S 1 +x 2 ×S 2 ) / E is greater than or equal to 0.4, thereby improving the over-current capacity of the electrode terminal, reducing the internal resistance of the battery cell, and being conducive to improving the fast charging ability of the battery cell with high energy density.

[0411] In Example 1, Example 2-1 to Example 2-3, the larger the over-current area of the electrode terminal, the stronger the over-current capacity, and the more conducive it is to reducing the internal resistance of the battery cell. However, the over-current area of the electrode terminal is limited by the assembly space, such that (x 1 ×S 1 +x 2 ×S 2 ) / E is less than or equal to 1.4.

[0412] Example 3 uses one negative terminal, Examples 2-3 use two negative terminals. The current-carrying area of the negative terminal in Example 3 is basically the same as that of each negative terminal in Examples 2-3. In other words, the current-carrying area of the negative terminal in Example 3 is smaller than the total current-carrying area of the two negative terminals in Examples 2-3. The current-carrying capacity of the negative terminal in Example 3 is less than the total current-carrying capacity of the negative terminals in Examples 2-3, and the internal resistance of Example 3 is relatively high. However, since Example 3 uses one positive terminal, and the current-carrying area of one positive terminal is basically the same as the total current-carrying area of the two positive terminals in Examples 2-3, the current-carrying capacity of the positive terminal in Example 3 is basically the same as that in Examples 2-3. The current-carrying capacity of the positive terminal is strong, making the overall current-carrying capacity of the battery cell relatively strong, which is beneficial for fast charging.

[0413] In Example 1, Examples 4-1 and Examples 4-2, by adjusting the welding mark area between the electrode terminal and the tab part, the current-carrying capacity between the electrode terminal and the tab part is adjusted. As the welding mark area increases, the current-carrying capacity becomes stronger, the internal resistance becomes smaller, and it is more beneficial for the battery cell with high energy density to improve the fast charging ability.

[0414] Examples 5-1 and 5-2 The battery cell is prepared by a method similar to that of Example 1. Different from Example 1, the size of the battery cell is adjusted.

[0415] The test results are shown in Table 3.

[0416] Table 3

[0417] In each example and comparative example, the width of the battery cell is 100 mm, the thickness is 10 mm, and the ratio of the width to the thickness is 10.

[0418] In Comparative Example 1, not only is the current-carrying capacity of the electrode terminal insufficient, but also due to the short size of the battery cell, the energy density of the battery cell is small.

[0419] Compared with Comparative Example 2, the aspect ratio of the positive electrode film layer in the embodiment of the present application is 4 to 7. The size of the battery cell is within an appropriate range, which can make the battery cell have a relatively high energy density; and combined with the appropriate number and proper position setting of the electrode terminals, for example, two positive terminals are respectively arranged on both sides of the electrode assembly along the length direction, which can effectively shorten the electron transmission path, improve the current-carrying capacity, reduce the internal resistance, and enhance the fast charging ability of the battery cell.

[0420] Examples 6-1 to 6-2 The battery cell is prepared by a method similar to that of Example 1. Different from Example 1, the single-sided coating weight of the positive and negative electrode film layers is adjusted.

[0421] Examples 6-3 to 6-4 The battery cells were prepared using a method similar to that of Example 1. The difference from Example 1 was that the compaction density of the positive and negative electrode film layers was adjusted.

[0422] The test results are shown in Table 4.

[0423] Table 4

[0424] The single-sided coating weight of the positive and negative electrode film layers was adjusted. When the single-sided coating weight was relatively high, it was beneficial to improve the single-cell energy of the battery cell and increase the energy density. However, since the migration path of lithium ions in the positive and negative electrode film layers increased, the DCR deteriorated slightly.

[0425] The single-sided coating weights of the positive and negative electrode film layers in Examples 6-1 and 6-2 were within an appropriate range. For example, the single-sided coating weight of the positive electrode film layer was 250 mg / 1540.25 mm 2 to 330 mg / 1540.25 mm 2 , and the single-sided coating weight of the negative electrode film layer was 120 mg / 1540.25 mm 2 to 180 mg / 1540.25 mm 2 , enabling the battery cell to balance a relatively high single-cell energy and a relatively low DCR, which was beneficial for balancing the improvement of the fast charging performance and energy density of the battery cell.

[0426] The compaction density of the positive and negative electrode film layers was adjusted. When the compaction density was relatively high, it was beneficial to improve the single-cell energy of the battery cell and increase the energy density. However, since the migration resistance of lithium ions in the positive and negative electrode film layers might increase, the DCR deteriorated slightly.

[0427] The single-sided coating weights of the positive and negative electrode film layers in Examples 6-3 and 6-4 were within an appropriate range. For example, the compaction density of the positive electrode film layer was 2.30 g / cm 3 to 2.70 g / cm 3 , and the compaction density of the negative electrode film layer was 1.30 g / cm 3 to 1.65 g / cm 3 , enabling the battery cell to balance a relatively high single-cell energy and a relatively low DCR, which was beneficial for balancing the improvement of the fast charging performance and energy density of the battery cell.

[0428] Although the illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limitations on the implementation manners of the present application, and the embodiments can be changed, substituted, and modified without departing from the spirit, principle, and scope of the implementation manners of the present application.

Claims

1. A battery cell, characterized in that: include: An electrode assembly, comprising a plurality of first pole sheets and a plurality of second pole sheets, wherein the first pole sheets and the second pole sheets are stacked along the thickness direction of the battery cell, and each of the first pole sheets and the second pole sheets comprises a coating portion and a pole ear portion, wherein the coating portion is provided with an active material layer, and the pole ear portion is connected to the coating portion and extends out of the coating portion; as well as A shell assembly, comprising a shell and a terminal assembly arranged on the shell, wherein the shell accommodates the electrode assembly, the terminal assembly comprises at least one first electrode terminal and at least one second electrode terminal, the first electrode terminal is connected to the pole ear portion of the first pole piece, and the second electrode terminal is connected to the pole ear portion of the second pole piece, Wherein, one of the first electrode sheet and the second electrode sheet is a positive electrode sheet, and the other is a negative electrode sheet, and the active material layer of the positive electrode sheet includes a lithium-containing phosphate with an olivine structure; The size of the coating portion of the positive electrode sheet along the length direction of the battery cell is a first size, the size of the coating portion of the positive electrode sheet along the width direction of the battery cell is a second size, and the ratio of the first size to the second size is 4 to 7; The battery cell satisfies: (x1×S1+x2×S2) / E is 0.4 to 1.4, x1 represents the number of the first electrode terminals; x2 represents the number of the second electrode terminals; S1 represents the minimum cross-sectional area of ​​a single first electrode terminal perpendicular to its own thickness direction, and its unit is mm 2 ; S2 represents the minimum cross-sectional area of ​​a single second electrode terminal perpendicular to its own thickness direction, and its unit is mm 2 ; E represents the single cell energy of the battery cell, and its unit is Wh.

2. The battery cell according to claim 1, characterized in that: S1 is from 15 to 60; and / or S2 is from 15 to 60.

3. The battery cell according to claim 1 or 2, characterized in that: x1 is 1 to 4; and / or x2 is 1 to 4.

4. The battery cell according to any one of claims 1 to 2, characterized in that: The battery cell also satisfies: M1 / E is 0.2 to 0.6; M1 represents the area of ​​the first connection area, and its unit is mm 2 ; The first connection area is a region of the at least one first electrode terminal connected to the pole ear portion of the first pole piece; and / or The battery cell also satisfies: M2 / E is 0.2 to 0.6, M2 represents the area of ​​the second connection area, and its unit is mm 2 ; The second connection area is the area of ​​the at least one second electrode terminal that is connected to the pole ear portion of the second pole piece.

5. The battery cell according to claim 4, characterized in that: M1 is from 60 to 120; and / or M2 is from 60 to 120.

6. The battery cell according to any one of claims 1 to 2, characterized in that: E is 170 to 480.

7. The battery cell according to any one of claims 1 to 2, characterized in that: The first electrode terminal is disposed on at least one side of the electrode assembly along the length direction; and / or The second electrode terminal is disposed on at least one side of the electrode assembly along the length direction.

8. The battery cell according to any one of claims 1 to 2, characterized in that: There are at least two first electrode terminals, and the at least two first electrode terminals are respectively arranged on both sides of the electrode assembly along the length direction; and / or There are at least two second electrode terminals, and the at least two second electrode terminals are respectively arranged on both sides of the electrode assembly along the length direction.

9. The battery cell according to any one of claims 1 to 2, characterized in that: The housing comprises a shell and an end cover, the shell contains the electrode assembly, the shell comprises an opening, the end cover covers the opening, and the first electrode terminal is arranged on the end cover; The first electrode terminal comprises: A first main body, disposed on the housing and passing through the end cover; as well as The first protrusion is arranged on the first main body and protrudes from the first main body to be connected with a side of the end cover facing the electrode assembly.

10. The battery cell according to claim 9, characterized in that: In a direction from the first main body to the first protrusion, a size of the first protrusion is 1.5 mm to 30 mm.

11. The battery cell according to claim 9, characterized in that: The first main body and the first protruding portion are an integrated structure.

12. The battery cell according to claim 9, characterized in that: The first main body is disposed on the end cover and penetrates the end cover, and a ratio of a dimension of the first main body along a thickness direction of the battery cell to a dimension of the end cover along a thickness direction of the battery cell is 0.20 to 0.

40.

13. The battery cell according to claim 9, characterized in that: The shell assembly also includes a first conductive fixing member, at least part of which is located on a side of the end cover away from the electrode assembly, and the first conductive fixing member is disposed around the outside of the first main body and fixedly connects the first main body and the end cover.

14. The battery cell according to claim 13, characterized in that: A ratio of a dimension of the first conductive fixing member along a thickness direction of the battery cell to a dimension of the end cover along a thickness direction of the battery cell is 0.40 to 0.

80.

15. The battery cell according to any one of claims 1 to 2, characterized in that: The pole ear portion of the first pole piece is arranged on at least one side of the coating portion along the first direction, and the first pole piece satisfies: n*W1 / W2 is 0.5 to 1.0; n represents the number of all the pole lugs located on the same side of the coating portion; W1 represents the average size of the pole ear portion along the second direction, one of the first direction and the second direction is parallel to the length direction of the battery cell, and the other is parallel to the width direction of the battery cell; W2 represents a dimension of the coating portion along the second direction.

16. The battery cell according to claim 15, characterized in that: The first direction is parallel to a length direction of the battery cell.

17. The battery cell according to any one of claims 1 to 2, characterized in that: There are at least two pole lug portions in the first pole piece located on the same side of the coating portion.

18. The battery cell according to claim 16, characterized in that: The first pole piece has a plurality of pole ear portions, and the plurality of pole ear portions of the first pole piece are located on both sides of the coating portion along the first direction; or All the pole lug portions of the first pole piece are located on the same side of the coating portion along the first direction.

19. The battery cell according to any one of claims 1 to 2, characterized in that: The ratio of the length of the battery cell to the thickness of the battery cell is 40 to 70; and / or A ratio of a width of the battery cell to a thickness of the battery cell is 3 to 15.

20. The battery cell according to any one of claims 1 to 2, characterized in that: The thickness of the battery cell is 10 mm to 30 mm.

21. The battery cell according to any one of claims 1 to 2, characterized in that: The olivine-structured lithium-containing phosphate includes lithium iron phosphate.

22. The battery cell according to any one of claims 1 to 2, characterized in that: The single-sided coating weight of the active material layer of the positive electrode sheet is 250 mg / 1540.25 mm 2 Up to 330mg / 1540.25mm 2 ; and / or The compaction density of the active material layer of the positive electrode sheet of the battery cell at 0% charge state is 2.30 g / cm 3 Up to 2.70g / cm 3 .

23. The battery cell according to any one of claims 1 to 2, characterized in that: The single-sided coating weight of the active material layer of the negative electrode plate is 120 mg / 1540.25 mm 2 Up to 180mg / 1540.25mm 2 ; and / or The compaction density of the active material layer of the negative electrode sheet of the battery cell at 0% charge state is 1.30 g / cm 3 Up to 1.65g / cm 3 .

24. The battery cell according to any one of claims 1 to 2, characterized in that: The coating portion of the negative electrode sheet includes a negative electrode current collecting portion and a negative electrode film layer disposed on at least one side of the negative electrode current collecting portion, wherein the negative electrode film layer includes a negative electrode active material, wherein the negative electrode active material includes a carbon-based material, wherein the negative electrode film layer includes: A first negative electrode film layer is disposed on the surface of the negative electrode current collecting portion; and A second negative electrode film layer is connected to a side of the first negative electrode film layer away from the negative electrode current collecting portion, The volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is greater than or equal to the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer.

25. The battery cell according to claim 24, characterized in that: The carbon-based material of the first negative electrode film layer is granular, and its volume average particle size Dv50 is 9.5 μm to 18.5 μm; and / or The carbon-based material of the second negative electrode film layer is granular, and its volume average particle size Dv50 is 7.8 μm to 14.3 μm.

26. The battery cell according to claim 24, characterized in that: The carbon-based material of the first negative electrode film layer includes at least one of artificial graphite and natural graphite, and the carbon-based material of the second negative electrode film layer includes artificial graphite.

27. The battery cell according to any one of claims 1 to 2, characterized in that: The invention also includes an electrolyte having an electrical conductivity of 10 mS / cm to 13 mS / cm at room temperature.

28. The battery cell according to claim 27, characterized in that: The electrolyte includes an organic solvent, and the organic solvent includes a chain carboxylate solvent. The mass content of the chain carboxylate solvent is 5% to 30% based on the mass of the electrolyte.

29. The battery cell according to claim 27, characterized in that: The electrolyte includes a lithium salt, wherein the lithium salt includes lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide. Based on the mass of the electrolyte, a ratio of the mass content of the lithium hexafluorophosphate to the mass content of the lithium bis(fluorosulfonyl)imide is 0.5 to 4.

30. A battery device, characterized in that: The invention comprises the battery cell according to any one of claims 1 to 29.

31. An electrical device, characterized in that: Comprising a battery device as claimed in claim 30.

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