Battery cells, battery devices, and power-consuming devices

Abstract

The present application relates to a battery cell, a battery device, and an electrical device. The battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a first electrode sheet and a second electrode sheet, which are stacked along the thickness direction. Each of the first electrode sheet and the second electrode sheet includes 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 outward from the coating portion along the width direction of the battery cell. One of the first and second electrode sheets is a positive electrode sheet, and the other is a negative electrode sheet. The positive electrode sheet includes an olivine-structured lithium-containing phosphate. The coating portion of the positive electrode sheet has a first dimension along the length direction, and a second dimension along the width direction. The ratio of the first dimension to the second dimension is 4 to 7. The electrolyte includes lithium bis(fluorosulfonyl)imide, and the mass content of lithium bis(fluorosulfonyl)imide in the electrolyte is 1% to 15%. The battery cell of the present application can improve the fast charging capability and cycle performance.

Description

[0001] This application claims priority to patent application PCT / CN2025 / 071045, filed on January 7, 2025, entitled “Battery Cell, Battery Device, and Electrical Device,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to a battery cell, a battery device and an electrical device. Background Art

[0003] Battery cells, with their high capacity and long lifespan, are widely used in electronic devices such as mobile phones, laptops, electric bicycles, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy planes, and power tools. As batteries have advanced significantly, so too have the demands for higher performance. However, the fast charging capability and cycle performance of battery cells need to be further improved. Summary of the Invention

[0004] The present application provides a battery cell, a battery device, and an electrical device. The fast charging capability and cycle performance of the battery cell of the present application can be further improved.

[0005] In a first aspect, an embodiment of the present application proposes a battery cell, which includes an electrode assembly and an electrolyte, the electrode assembly including a plurality of first electrode sheets and a plurality of second electrode sheets, the first electrode sheets and the second electrode sheets are stacked along the thickness direction of the battery cell, the first electrode sheet and the second electrode sheet each include a coating portion and a pole ear portion, the coating portion is provided with an active material layer, the pole ear portion is connected to the coating portion and extends out of the coating portion along the width direction of the battery cell, 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, the active material layer of the positive electrode sheet includes a lithium-containing phosphate with an olivine structure; the dimension of the coating portion of the positive electrode sheet along the length direction of the battery cell is a first dimension, the dimension of the coating portion of the positive electrode sheet along the width direction is a second dimension, and the ratio of the first dimension to the second dimension is 4 to 7; the electrolyte includes lithium bis(fluorosulfonyl)imide, and the mass content of lithium bis(fluorosulfonyl)imide in the electrolyte is 1% to 15%.

[0006] In an embodiment of the present application, the ratio of the length of the coating portion of the positive electrode sheet to the width of the coating portion of the positive electrode sheet is 4 to 7. The relatively long coating portion is conducive to carrying a relatively large amount of positive electrode active material, which is conducive to making the battery cell have a relatively high energy density. When the battery cell has the above-mentioned stacked structure, the electron transmission path may be long, resulting in high internal resistance and increased heat generation. In addition, the lithium-containing phosphate has poor conductivity, which further increases the internal resistance and heat generation. As the charge rate increases, the above heat generation phenomenon intensifies, which is not conducive to fast charging. In the embodiment of the present application, the electrode ear portion is provided on at least one side of the coating portion along the width direction, so that the electron transmission path in the coating portion is short, which can reduce the ohmic resistance. In addition, the lithium salt of the electrolyte also includes lithium bis(fluorosulfonyl)imide with a mass content of 1% to 15%, which makes the electrolyte have strong ion conductivity and can reduce the internal resistance of the electrochemical system. Through the design of the electrode ear portion and the electrolyte, the embodiment of the present application comprehensively reduces the internal resistance of the battery cell, which is conducive to reducing heat generation and improving the fast charging capability and cycle performance of the battery cell.

[0007] In some embodiments, the lithium salt further comprises lithium hexafluorophosphate, and the ratio of the mass content of lithium hexafluorophosphate to the mass content of lithium bis(fluorosulfonyl)imide, based on the mass of the electrolyte, is 0.5 to 4, and optionally 1.2 to 2. The lithium salt is beneficial in improving the electrolyte's ability to conduct lithium ions, enhancing the kinetic performance of the battery cells, and can reduce the hydrofluoric acid content in the electrolyte, thereby improving the performance of the solid electrolyte membrane on the negative electrode side, and enhancing the fast charging capability and cycling performance of the battery cells.

[0008] In some embodiments, the mass content of lithium bis(fluorosulfonyl)imide in the electrolyte is 3% to 12%. The above mass content of lithium salt is beneficial for improving the fast charging capability and cycle performance of the battery cell.

[0009] In some embodiments, the electrolyte has a conductivity of 10 mS / cm to 13 mS / cm at room temperature. The high migration rate of lithium ions in the electrolyte can further reduce the internal resistance of the battery cell, thereby reducing heat generation and improving the fast charging performance of the battery cell.

[0010] In some embodiments, the electrolyte further includes an organic solvent, including a chain carboxylate solvent. The chain carboxylate solvent improves the conductivity of the electrolyte at room temperature, facilitates the migration of lithium ions, and improves the fast charging capability of the battery cell.

[0011] In some embodiments, the chain carboxylate ester solvent comprises 5% to 30% by weight of the electrolyte. This amount of chain carboxylate ester solvent can improve the conductivity of the electrolyte, thereby improving the fast charging capability of the battery cells.

[0012] In some embodiments, the first pole piece satisfies the following conditions: n*W1 / W2 is 0.5 to 1.0; n represents the number of pole lugs located on the same side of the coating; W1 represents the average length of the pole lug; and W2 represents the length of the coating. The connection area between the pole lug and the coating is relatively large, and the pole lug has a relatively large flow area, which helps reduce DC resistance and heat generation, thereby improving fast charging capabilities.

[0013] In some embodiments, W2 is 300 mm to 650 mm; and / or n*W1 is 150 mm to 650 mm.

[0014] In some embodiments, the first pole piece includes a plurality of pole ears, which can enhance the current flow capacity and facilitate the improvement of the fast charging capability.

[0015] In some embodiments, there are at least two pole lugs on the same side of the coating portion of the first pole piece, and the distance between two adjacent pole lugs along the length direction is greater than 0 and less than or equal to 300 mm. The above arrangement can enhance the current capacity and improve the fast charging capability.

[0016] In some embodiments, the plurality of pole lugs of the first pole piece are located on both sides of the coating portion along the width direction. The above arrangement shortens the electron transmission path, which is conducive to improving the fast charging capability.

[0017] In some embodiments, all the tabs of the first pole piece are located on the same side of the coating portion along the width direction. The above arrangement can enhance the current capacity and is conducive to improving the fast charging capability.

[0018] In some embodiments, the width of the coating portion of the first electrode is greater than 0 and less than or equal to 300 mm. The above configuration shortens the electron transmission path, which is beneficial for improving the fast charging capability.

[0019] In some embodiments, the battery cell further includes a first electrode terminal connected to the tab portion of the first electrode sheet. The first electrode terminal is disposed on at least one side of the electrode assembly along its length. The first electrode terminal and the tab portion are disposed on opposite sides of the electrode assembly, thereby increasing the internal space of the battery cell in the width direction and improving the energy density of the battery cell.

[0020] In some embodiments, the battery cell further includes a second electrode terminal connected to the tab portion of the second electrode sheet. The second electrode terminal is disposed on at least one side of the electrode assembly along its length. The second electrode terminal and the tab portion are disposed on opposite sides of the electrode assembly to facilitate expansion of the internal space of the battery cell in its width direction, thereby increasing the energy density of the battery cell.

[0021] In some embodiments, all of the tabs of the first electrode piece are located on the same side of the coating portion, and all of the tabs of the second electrode piece are located on the same side of the coating portion. The tabs of the first electrode piece and the tabs of the second electrode piece are located on opposite sides of the coating portion along the width direction, respectively. There is one first electrode terminal and one second electrode terminal, respectively, located on opposite sides of the electrode assembly along the length direction. The first electrode terminal and the second electrode terminal are staggered along the width direction, with the first electrode terminal located closer to the tab of the first electrode piece and the second electrode terminal located closer to the tab of the second electrode piece. This arrangement shortens the electron transmission path, which is beneficial for improving fast charging capability.

[0022] In some embodiments, there are two first electrode terminals, which are respectively disposed on both sides of the electrode assembly along the length direction. Such a configuration shortens the electron transmission path, which is beneficial for improving the fast charging capability.

[0023] In some embodiments, there are two second electrode terminals, which are respectively disposed on both sides of the electrode assembly along the length direction. This arrangement shortens the electron transmission path, which is beneficial for improving the fast charging capability.

[0024] In some embodiments, the battery cell further includes a first adapter, which is positioned between the first electrode terminal and the tab portion of the first pole piece, and connects the first electrode terminal to the tab portion of the first pole piece. The first adapter further facilitates the connection between the first tab and the first electrode terminal. The first adapter can increase current flow capacity, reduce heat generation, and improve the fast charging capability of the battery cell.

[0025] In some embodiments, the first adapter includes a first adapter portion and a second adapter portion. The first adapter portion extends in the longitudinal direction and connects to the electrode tab portion. The second adapter portion is connected to the first adapter portion, protrudes from the first adapter portion in the width direction, and is connected to the first electrode terminal. The first and second adapter portions can improve the flow capacity between the electrode tab portion and the first electrode terminal, reduce heat generation, and improve the fast charging capability of the battery cell.

[0026] In some embodiments, the tab portion includes a first region connected to the first adapter, and the ratio of the length of the first region to the length of the tab portion is 0.5 to 1. When the first tab meets the above conditions, the contact area between the first tab and the first adapter is relatively large, resulting in a stronger current carrying capacity and a relatively lower ohmic resistance of the first tab, which is conducive to improving the fast charging capability of the battery cell.

[0027] In some embodiments, the tab portion is disposed on at least one side of the coating portion along the width direction of the battery cell, and the tab portion extends in the length direction with a gap between the tab portion and the coating portion. The battery cell further includes a heat conduction member disposed at least within the gap. The heat conduction member is capable of conducting heat generated by the tab portion, rapidly transferring the heat generated by the tab portion, and reducing the risk of heat-induced erosion of the separator in the electrode assembly.

[0028] In some embodiments, the battery cell further includes a housing that houses the electrode assembly and electrolyte, wherein the heat-conducting member extends to and contacts the housing. The heat-conducting member can quickly transfer heat generated by the electrode lug to the housing, reducing the risk of heat-induced erosion of the separator in the electrode assembly.

[0029] 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 conducive to rapid heat dissipation inside the battery cell and reduces the risk of thermal runaway.

[0030] In some embodiments, the battery cell further includes a housing comprising two first shell portions opposing each other along the thickness direction, and a second shell portion and a third shell portion opposing each other. The second shell portion and the third shell portion are connected by the first shell portion. The second shell portion includes a first wall and a second wall continuously disposed along the thickness direction, and the first and second walls are welded. The second shell portion has a relatively small area and relatively small expansion, and the weld is located on the second shell portion, which can reduce the risk of leakage in the battery cell.

[0031] In some embodiments, the shell has a thickness of 0.1 mm to 0.5 mm. When the shell thickness is within the above range, the shell is relatively thin, which is conducive to rapid heat dissipation from the shell, reducing the risk of heat accumulation in the system leading to aggravated side reactions, and improving the cycle performance of the battery cell.

[0032] In some embodiments, the olivine-structured lithium-containing phosphate includes lithium iron phosphate. Lithium iron phosphate has excellent cycle stability and can improve the cycle performance of battery cells.

[0033] In some embodiments, the positive electrode sheet includes a positive electrode film layer, and the single-side coating weight of the positive electrode film layer is 250 mg / 1540.25 mm 2 Up to 330mg / 1540.25mm 2 When the single-sided coating weight of the positive electrode film layer is within the above range, the heat generated per unit area of ​​the positive electrode sheet will not be too large, and both the energy density and fast charging capability of the battery cell can be improved.

[0034] In some embodiments, the compaction density of the positive electrode film layer of the battery cell at 0% state of charge is 2.30 g / cm 3to 2.70g / 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. Moreover, since the positive electrode active material in the positive electrode film layer is relatively densely packed, the contact resistance between particles is relatively small, which can further reduce the resistance of the electrode sheet, thereby reducing heat generation under fast charging and improving the fast charging capability and cycle performance of the battery cell.

[0035] In some embodiments, the coating portion of the negative electrode plate 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, the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material, wherein the negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer, wherein the first negative electrode film layer is disposed on the surface of the negative electrode current collecting portion; and 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 collecting portion, wherein 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 fast charging performance, and can improve the problem of lithium plating on the surface of the negative electrode plate, thereby improving the cycle performance of the battery cell.

[0036] 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 easy to agglomerate during the preparation process, which can improve the stability of the material.

[0037] In some embodiments, the carbon-based material of the second negative electrode film layer is granular and has a volume average particle size Dv50 of 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 this range, the solid-phase transport path of lithium ions can be shortened, thereby improving fast charging performance.

[0038] 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.

[0039] In some embodiments, the coating portion of the negative electrode plate 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, the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material, wherein the negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer, wherein the first negative electrode film layer is disposed on the surface of the negative electrode current collecting portion; and 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 collecting portion, wherein the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is smaller than 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 fast charging performance, and improve the problem of lithium plating on the surface of the negative electrode plate, thereby improving the cycle performance of the battery cell.

[0040] In some embodiments, the carbon-based material of the second 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 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 easy to agglomerate during the preparation process, which can improve the stability of the material.

[0041] In some embodiments, the carbon-based material of the first negative electrode film layer is granular and has a volume average particle size Dv50 of 7.8 μm to 14.3 μm. When the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is within this range, the solid-phase transport path of lithium ions can be shortened, thereby improving fast charging performance.

[0042] In some embodiments, 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.

[0043] In some embodiments, the single-sided coating weight of the negative electrode film layer is 120 mg / 1540.25 mm 2 Up to 180mg / 1540.25mm 2 When the single-sided coating weight of the negative electrode film layer is within the above range, the heat generated per unit area of ​​the negative electrode sheet will not be too large, and the energy density of the battery cell can be improved.

[0044] In some embodiments, the compaction density of the negative electrode film layer of the battery cell at 0% state of charge is 1.30 g / cm 3 Up to 1.65g / 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. Moreover, since the negative electrode active material in the negative electrode film layer is densely packed, the contact resistance between particles is small, which can further reduce the resistance of the electrode sheet, thereby reducing heat generation and improving the fast charging capability and cycle performance of the battery cell.

[0045] In a second aspect, an embodiment of the present application further provides a battery device, comprising a battery cell according to any embodiment of the first aspect of the present application.

[0046] In a third aspect, an embodiment of the present application further proposes an electrical device, which includes a battery device as in any embodiment of the second aspect or the third aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0048] Figure 1 is a schematic structural diagram of an electrical device provided in some embodiments of the present application;

[0049] Figure 2 is a schematic structural diagram of a battery pack provided in some embodiments of the present application;

[0050] Figure 3 is a schematic structural diagram of a battery module provided in some embodiments of the present application;

[0051] Figure 4 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0052] Figure 5 is a schematic structural diagram of an electrode assembly of a battery cell provided in some embodiments of the present application;

[0053] Figure 6 is a schematic structural diagram of a first pole piece of a battery cell provided in some embodiments of the present application;

[0054] Figure 7 is a schematic structural diagram of a first pole piece of a battery cell provided in other embodiments of the present application;

[0055] Figure 8 is a schematic structural diagram of a first pole piece of a battery cell provided in some further embodiments of the present application;

[0056] Figure 9 is a schematic structural diagram of a first pole piece of a battery cell provided in some embodiments of the present application;

[0057] Figure 10 is a schematic structural diagram of a first pole piece of a battery cell provided in some embodiments of the present application;

[0058] Figure 11 is a schematic structural diagram of a second pole piece of a battery cell provided in some embodiments of the present application;

[0059] Figure 12 is a schematic structural diagram of a second pole piece of a battery cell provided in other embodiments of the present application;

[0060] Figure 13 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0061] Figure 14 is a schematic structural diagram of a battery cell provided in some other embodiments of the present application;

[0062] Figure 15 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0063] Figure 16 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0064] Figure 17 Schematic diagram of the structure of the end cover, the first electrode terminal and the first conductive fixing member of the battery cell provided in some embodiments of the present application;

[0065] Figure 18 yes Figure 17 Schematic top view of

[0066] Figure 19 yes Figure 18 Sectional view along line AA;

[0067] Figure 20 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0068] Figure 21 It is a schematic structural diagram of a battery cell provided in some other embodiments of the present application.

[0069] The drawings are not necessarily drawn to scale.

[0070] The following are the descriptions of the reference numerals:

[0071] X, thickness direction; Y, width direction; Z, length direction;

[0072] 1. Power-consuming device; 2. Battery pack; 3. Controller; 4. Motor; 5. Box; 5a. First box portion; 5b. Second box portion; 5c. Accommodation space; 6. Battery module;

[0073] 7. Battery cells;

[0074] 10. Electrode assembly;

[0075] 11. First pole piece; 111. First pole tab; 1111. First end; 112. First coating portion;

[0076] 12. Second pole piece; 121. Second pole tab; 1211. Second end; 122. Second coating portion;

[0077] 13. Isolation parts;

[0078] 20. Housing assembly;

[0079] 21. Shell; 211. First shell portion; 212. Second shell portion; 2121. First wall; 2122. Second wall; 213. Third shell portion;

[0080] 22. End cap;

[0081] 31. First electrode terminal; 311. First electrode body; 312. First electrode protrusion;

[0082] 32. a second electrode terminal;

[0083] 41. a first conductive fixing member;

[0084] 51, first adapter; 511, first adapter portion; 512, second adapter portion;

[0085] 61, first conductive member; 611, first conductive portion; 612, second conductive portion;

[0086] 81. A first heat conducting member. DETAILED DESCRIPTION

[0087] Below, the embodiments of the battery cells, battery devices, and electrical devices of the present application are described in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially the same structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0088] " Range " disclosed in this application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be inclusive or exclusive of end values, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that the range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3,4 and 5 are listed, then the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In this application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, a numerical range of "0 to 5" indicates that all real numbers between "0 and 5" are listed herein, and "0 to 5" is merely an abbreviation for the combination of these values. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0089] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0090] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0091] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, a method includes steps (a) and (b), which indicates that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a method may further include step (c), which indicates that step (c) may be added to the method in any order, for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0092] The term "plurality" used in this application refers to two or more (including two).

[0093] Battery cells will have internal resistance during the charging process, especially electrode assemblies with longer sizes. Although the advantage of longer size gives it an advantage in energy density, the long electron transmission path makes the internal resistance of the battery cells higher, causing the internal temperature of the battery cells to rise excessively during charging, which is not conducive to fast charging. In addition, due to the excessive temperature rise, the side reactions in the battery cell system are aggravated, and the high-temperature cycle performance may deteriorate.

[0094] In view of the above problems, the embodiments of this application design elongated battery cells. Combined with the comprehensive design of the aspect ratio of the positive electrode film layer, the tab method, and the electrolyte composition, the internal resistance of the battery cell is improved by reducing the ohmic resistance and chemical system resistance within the battery cell. By setting the position of the tab, the electron transmission path is shortened and the ohmic resistance is reduced. Combined with the design of the electrolyte composition, the ion conductivity of the electrolyte is enhanced, reducing the internal resistance of the electrochemical system. This comprehensive reduction in the internal resistance of the battery cell is beneficial to reducing heat generation and improving the fast charging capability and high-temperature cycling performance of the battery cell.

[0095] The battery cell of the present application is applicable to various battery devices and electrical devices using the battery cell.

[0096] For example, the power-consuming device may be a mobile phone, portable device, laptop computer, electric vehicle, electric toy, electric tool, vehicle, ship, spacecraft, etc. Alternatively, for example, the power-consuming device may be a spacecraft, including an airplane, rocket, space shuttle, and spacecraft.

[0097] Figure 1 This is a schematic diagram of the structure of an electric device 1 provided in some embodiments of the present application. The electric device 1 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the electric device 1, a battery pack or battery module can be used.

[0098] A battery device is disposed within the electrical device 1, and the battery device can be disposed at the bottom, head, or tail of the electrical device 1. The battery device can be used to power the electrical device 1. For example, the battery device can serve as an operating power source for the electrical device 1, and can also serve as a driving power source for 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 FIG. 1 is a battery pack 2 .

[0099] The electric 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, to meet the power requirements of the electric device 1 during startup, navigation, and driving.

[0100] A battery device may include one or more battery cell assemblies to provide voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or in series via a busbar.

[0101] In some embodiments, a battery cell assembly is generally formed by arranging a plurality of battery cells.

[0102] As an example, the battery cell assembly may be a battery module, which is formed by arranging and fixing multiple battery cells to form an independent module. As an example, the battery module may be formed by bundling multiple battery cells with a cable tie.

[0103] like Figure 2 As shown, in some embodiments, the battery device may be a battery pack 2 , which includes a box 5 and one or more battery cell assemblies, wherein the battery cell assemblies are accommodated in the box 5 .

[0104] As an example, the battery cell assembly may also be housed in the box body 5 by directly fixing a plurality of battery cells to the box body 5 .

[0105] As an example, the housing 5 includes a first housing portion 5a and a second housing portion 5b, which define a storage space 5c. The first housing portion 5a and the second housing portion 5b engage to form a closed space within the housing 5 for accommodating the battery cell assembly. "Enclosed" here means covered or closed, and can be either sealed or unsealed. The first housing portion 5a can be a top cover or a bottom plate.

[0106] 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.

[0107] In some embodiments, the box 5 can be used as a part of the chassis structure of the vehicle. For example, part of the box 5 can become at least a part of the floor of the vehicle, or part of the box 5 can become at least a part of the crossbeam and longitudinal beam of the vehicle.

[0108] As an example, the battery cell assembly may be a battery module 6 , and the battery cell assembly may be accommodated in the box body 5 by fixing the battery module 6 in the box body 5 .

[0109] like Figure 3 As shown, the battery module 6 includes a plurality of battery cells 7 .

[0110] 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 of the battery device is room temperature, for example, 25° C.

[0111] In some embodiments, during the charging process of the battery device or any battery cell constituting the battery device from 10% SOC to 80% SOC, the temperature of the external environment of the battery device is room temperature, for example, 25° C.

[0112] For example, the charging step of the battery device or any battery cell constituting the battery device from 10% SOC to 80% SOC may be performed as follows:

[0113] Charge from 10% SOC to 25% SOC at 7.0C constant current;

[0114] Charge from 25% SOC to 30% SOC at 7.0C constant current;

[0115] Charge from 30% SOC to 35% SOC at 7.0C constant current;

[0116] Charge from 35% SOC to 40% SOC at 7.0C constant current;

[0117] Charge from 40% SOC to 45% SOC at 6.7C constant current;

[0118] Charge from 45% SOC to 50% SOC at 6.5C constant current;

[0119] Charge from 50% SOC to 55% SOC at 6.0C constant current;

[0120] Charge from 55% SOC to 60% SOC at 5.8C constant current;

[0121] Charge from 60% SOC to 65% SOC at 5.5C constant current;

[0122] Charge from 65% SOC to 70% SOC at 5.2C constant current;

[0123] Charge from 70% SOC to 75% SOC at 5.0C constant current;

[0124] Charge from 75% SOC to 80% SOC at 4.8C constant current.

[0125] In some embodiments, the charging time of the battery device or any battery cell constituting the battery device from 10% state of charge to 80% state of charge is 5 min to 20 min, optionally less than or equal to 12 min, and further optionally 5 min to 8 min. The ambient temperature of the battery device at 10% state of charge is room temperature, for example, 25° C. Exemplarily, the charging time 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 a range consisting of any two of the above values.

[0126] like Figures 4 to 6 As shown, the battery cell 7 includes an electrode assembly 10 and an electrolyte.

[0127] The electrode assembly 10 includes a plurality of first pole sheets 11 and a plurality of second pole sheets 12. The first pole sheets 11 and the second pole sheets 12 are stacked along the thickness direction X of the battery cell 7. The first pole sheets 11 and the second pole sheets 12 each include a coating portion and a pole ear portion. The coating portion is provided with an active material layer. The pole ear portion is connected to the coating portion and extends beyond the coating portion along the width direction Y of the battery cell 7 and is not coated with the active material layer. One of the first pole sheet 11 and the second pole sheet 12 is a positive electrode sheet, and the other is a negative electrode sheet. The active material layer of the positive electrode sheet includes a positive electrode active material, and the positive electrode active material includes a lithium-containing phosphate with an olivine structure.

[0128] The dimension of the coating portion of the positive electrode sheet along the length direction Z is a first dimension, the dimension of the coating portion of the positive electrode sheet along the width direction Y is a second dimension, and the ratio of the first dimension to the second dimension is 4 to 7;

[0129] The electrolyte includes lithium salt, which includes lithium bis(fluorosulfonyl)imide, and the mass content of lithium bis(fluorosulfonyl)imide in the electrolyte is 1% to 15%.

[0130] For a clearer description of the present application, the tab portion of the first pole piece 11 is defined as the first pole piece 111, and the coated portion of the first pole piece 11 is defined as the first coated portion 112. The tab portion of the second pole piece 12 is defined as the second pole piece 121, and the coated portion of the second pole piece 12 is defined as the second coated portion 122. The electrode terminal having the same electrical properties as and electrically connected to the first pole piece 111 is the first electrode terminal 31, and the electrode terminal having the same electrical properties as and electrically connected to the second pole piece 121 is the second electrode terminal 32.

[0131] Optionally, the battery cell 7 further includes an isolation member 13 , which is located between the first pole piece 11 and the second pole piece 12 .

[0132] The polarities of the first electrode piece 11 and the second electrode piece 12 are opposite. When the first electrode piece 11 is a positive electrode piece, the second electrode piece 12 is a negative electrode piece. The first electrode terminal 31 is a positive electrode terminal, and the second electrode terminal 32 is a negative electrode terminal.

[0133] Alternatively, when the first electrode piece 11 is a negative electrode piece, the second electrode piece 12 is a positive electrode piece, the first electrode terminal 31 is a negative electrode terminal, and the second electrode terminal 32 is a positive electrode terminal.

[0134] The electrode assembly 10 can be a laminated structure, with multiple first pole sheets 11 and multiple second pole sheets 12 stacked. Compared with the wound structure, it is easier to increase the amount of active material coating on the laminated 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 part in the positive electrode sheet along the length direction Z to the size of the coating part in the positive electrode sheet along the width direction Y is 4 to 7, and the length of the coating part is relatively long, which is conducive to carrying relatively more positive electrode active materials, and is conducive to making the battery cell 7 have a relatively high energy density.

[0135] When the battery cell 7 has the above-mentioned laminated structure, the electron transmission path may be long, resulting in high internal resistance and increased heat generation. As the charge rate increases, the above-mentioned heat generation phenomenon intensifies, which is not conducive to fast charging. The positive electrode active material includes a lithium-containing phosphate with an olivine structure having poor conductivity, which further increases the internal resistance of the positive electrode sheet and increases heat generation.

[0136] The pole ear portion of the embodiment of the present application is arranged on at least one side of the coating portion along the width direction Y, so that the transmission path of electrons in the coating portion is shorter, which can reduce the ohmic resistance; and the lithium salt of the electrolyte also includes lithium bis(fluorosulfonyl)imide with a mass content of 1% to 15%, so that the ion conductivity of the electrolyte is stronger, which can reduce the internal resistance of the electrochemical system; the embodiment of the present application comprehensively reduces the internal resistance of the battery cell through the design of the pole ear portion and the electrolyte, which is beneficial to reducing heat generation, improving the fast charging capability of the battery cell, and further improving the high-temperature cycle performance.

[0137] In the embodiment of the present application, the size of the coating portion in the positive electrode sheet along the length direction Z is the first size, which can be understood as the length of the coating portion in the positive electrode sheet. The size of the coating portion in the positive electrode sheet along the width direction Y is the second size, which can be understood as the width of the coating portion in the positive electrode sheet. When the first electrode sheet 11 is a positive electrode sheet, Figure 6 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.

[0138] If the ratio of the length of the coating portion to the width of the coating portion in the positive electrode plate is too small, for example, less than 4, the load of active material is relatively small, which is not conducive to improving the energy density of the battery cell; if the ratio of the length of the coating portion to the width of the coating portion in the positive electrode plate is too large, for example, greater than 7, the length of the coating portion in the positive electrode plate is too long, the transmission path of electrons in the length direction of the positive electrode plate is too long, the resistance increases, and is not conducive to improving the fast charging performance of the battery cell.

[0139] The ratio of the length of the coating portion to the width of the coating portion in the positive electrode sheet of the embodiment of the present application is 4 to 7, for example, 4, 4.5, 5, 5.5, 6, 6.5, 7 or a range consisting of any two of the above values, which can take into account the improvement of the energy density and fast charging performance of the battery cell.

[0140] If the length of the coating portion in the positive electrode plate is too short, for example, less than 300 mm, the load of active material is relatively small, which is not conducive to improving the energy density of the battery cell; if the length of the coating portion in the positive electrode plate is too long, for example, greater than 650 mm, the length of the positive electrode film layer is too long, the electron transmission path in the length direction of the positive electrode plate is too long, the resistance increases, and is not conducive to improving the fast charging performance of the battery cell.

[0141] In some embodiments, the length of the coating portion of the positive electrode sheet is 300 mm to 650 mm, for example, 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, 505 mm, 550 mm, 600 mm, 650 mm, or a range consisting of any two of the foregoing values. Alternatively, the length of the coating portion of the positive electrode sheet is 400 mm to 505 mm. When the length of the coating portion of the positive electrode sheet falls within the above range, both the energy density and fast charging performance of the battery cell can be improved.

[0142] [Electrolyte]

[0143] During the charge and discharge process of a battery cell, active ions such as lithium ions are embedded and released back and forth between the positive electrode and the negative electrode, and the electrolyte plays the role of conducting active ions between the positive electrode and the negative electrode.

[0144] The electrolyte salt includes a lithium salt, including lithium bis(fluorosulfonyl)imide, and may further include lithium hexafluorophosphate (LiPF6). These lithium salts improve the electrolyte's ability to conduct lithium ions, reduce the internal resistance of the electrochemical system, reduce heat generation, and enhance the rapid charging capability and high-temperature cycling performance of the battery cells.

[0145] 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 optionally 1.2 to 2.0. The lithium salt improves the electrolyte's ability to conduct lithium ions, reduces the internal resistance of the electrochemical system, reduces heat generation, and enhances the rapid charging capability and high-temperature cycling performance of the battery cells.

[0146] Illustratively, 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 a range consisting of any two of the above values.

[0147] In the embodiments of this application, the weight content of lithium bis(fluorosulfonyl)imide is 1% to 15% based on the mass of the electrolyte, and can optionally be 3% to 12%. The lithium salt helps improve the electrolyte's ability to conduct lithium ions, reduces the internal resistance of the electrochemical system, helps reduce heat generation, and improves the fast charging capability and high-temperature cycling performance of the battery cells.

[0148] Illustratively, 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 a range consisting of any two of the above values.

[0149] In some embodiments, the electrolyte has a conductivity of 10 mS / cm to 13 mS / cm at room temperature. For example, the electrolyte has a conductivity of 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 consisting of any two of these values ​​at room temperature.

[0150] 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 high, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation and improving the fast charging performance and high-temperature cycle performance of the battery cell.

[0151] In the embodiment of the present application, the conductivity of the electrolyte at room temperature, for example, 25° C., is ionic conductivity, which can be tested using equipment and methods known in the art, for example, by referring to the industry standard HG-T 4067-2015.

[0152] In some embodiments, the organic solvent includes a carbonate-based solvent.

[0153] Optionally, the mass content of the carbonate solvent in the electrolyte is 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 consisting of any two of the above values. The above mass content of carbonate solvent can further improve the conductivity of the electrolyte at room temperature, which is beneficial to the migration of lithium ions; and the mass content of carbonate solvent is not too high, which can reduce high-temperature gas production and improve high-temperature cycle performance.

[0154] 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 further optionally, the carbonate solvent includes dimethyl carbonate. The combination of the above carbonate solvent and the chain carboxylate solvent improves the conductivity of the electrolyte at room temperature, which is beneficial to the migration of lithium ions.

[0155] In some embodiments, the organic solvent includes a linear carboxylate solvent.

[0156] Optionally, the mass content of the chain carboxylate solvent in the electrolyte is 5% to 30%. Exemplarily, the mass content of the chain carboxylate solvent is 5%, 10%, 15%, 20%, 25%, 30%, or a range consisting of any two of the above values.

[0157] When the mass content of the chain carboxylate solvent is within the above range, the viscosity of the electrolyte system is relatively small, which is conducive to the migration of lithium ions; and the mass content of the chain carboxylate solvent is not too high, which can reduce high-temperature gas production and improve high-temperature cycle performance.

[0158] In some embodiments, the linear carboxylate solvent includes a compound represented by Formula I,

[0159] Formula I,

[0160] In Formula I,

[0161] R1 includes a hydrogen atom, a C1 to C5 alkyl group or a C1 to C5 halogenated alkyl group,

[0162] R2 includes C1 to C5 alkyl or C1 to C5 halogenated alkyl.

[0163] The above-mentioned chain carboxylic acid ester solvents have high electrical conductivity, which is beneficial to improving the fast charging capability of battery cells.

[0164] Alternatively, R1 includes a hydrogen atom, a C1 to C3 alkyl group, or a C1 to C3 haloalkyl group. Further alternatively, R1 includes a hydrogen atom, a halogen atom, a C1 to C2 alkyl group, or a C1 to C2 haloalkyl group.

[0165] Alternatively, R2 comprises a C1 to C3 alkyl group or a C1 to C3 haloalkyl group. Further alternatively, R2 comprises a C1 to C2 alkyl group or a C1 to C2 haloalkyl group.

[0166] In each of 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.

[0167] Illustratively, the chain carboxylate solvent includes one or more compounds represented by formula I-1 to formula I-8.

[0168]

[0169] In some embodiments, the electrolyte further contains additives, which may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high temperature performance, additives that improve battery low temperature power performance, etc.

[0170] In some embodiments, the additives include one or more of carbonate additives and sulfur-containing additives, and optionally at least two of these additives. These additives can improve the interfacial film properties on the positive electrode side and / or the negative electrode side, thereby enhancing the fast charging performance of the battery cell and improving the cycling performance.

[0171] In some embodiments, the weight content of the additive in the electrolyte is 0.5% to 6%. For example, the weight 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 consisting of any two of the above values.

[0172] The above-mentioned organic solvents, such as chain carboxylic acid ester solvents, may decompose and produce acid at high temperatures, corroding the solid electrolyte interface film SEI film on the negative electrode surface. The additives can form a dense and uniformly thick SEI film on the negative electrode side, which can effectively repair the SEI film and provide excellent protection for the negative electrode active materials, which is beneficial to improving the fast charging performance of the battery cell and improving the cycle performance.

[0173] Illustratively, the carbonate additive includes one or more of vinylene carbonate VC and fluoroethylene carbonate FEC. Optionally, the carbonate additive includes vinylene carbonate VC and fluoroethylene carbonate FEC.

[0174] Vinylene carbonate VC can form a dense and uniformly thick SEI film on the negative electrode side, can effectively repair the SEI film, and provide excellent protection for the negative electrode active materials, which is beneficial to improving the fast charging performance and high-temperature cycle performance of the battery cell.

[0175] Fluoroethylene carbonate FEC can form a relatively low-impedance SEI film on the negative electrode side, effectively repair the SEI film, and provide excellent protection for the negative electrode active material, which is beneficial to improving the fast charging performance and high-temperature cycle performance of the battery cell.

[0176] Illustratively, the sulfur-containing additive includes one or more of vinyl sulfate DTD, vinyl disulfate 2-DTD, butylene sulfite BS, 1,3-propane sultone PS, vinyl sulfite ES, and methylene disulfonate MMDS, and 1,3-propane sultone PS may be selected.

[0177] Sulfur-containing additives can effectively repair the SEI film, provide excellent protection for the negative electrode active materials, and help improve the fast charging performance and high-temperature cycle performance of battery cells.

[0178] Illustratively, the additive includes one or more of vinylene carbonate, fluoroethylene carbonate, and 1,3-propane sultone.

[0179] Optionally, the mass content of vinylene carbonate (VC) in the electrolyte is 0.5% to 3.0%, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.5%, 3.0%, or a range consisting of any two of the foregoing values. When the mass content of vinylene carbonate (VC) in the electrolyte is within the foregoing range, it can effectively repair the SEI film, provide excellent protection for the negative electrode active material, and improve the fast charging performance and high-temperature cycling performance of the battery cell.

[0180] Optionally, the mass content of fluoroethylene carbonate (FEC) in the electrolyte is 0.2% to 2.5%, for example, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.5%, 2.0%, 2.5%, or a range consisting of any two of the foregoing values. When the mass content of fluoroethylene carbonate (FEC) in the electrolyte is within the foregoing range, it can effectively repair the SEI film, provide excellent protection for the negative electrode active material, and improve the fast charging performance and high-temperature cycling performance of the battery cell.

[0181] Optionally, the mass content of 1,3-propane sultone (PS) in the electrolyte is 0.5% to 2.5%, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.5%, or a range consisting of any two of these values. When the mass content of 1,3-propane sultone (PS) in the electrolyte is within the above range, it can effectively repair the SEI film, provide excellent protection for the negative electrode active material, and improve the fast charging performance and high-temperature cycling performance of the battery cell.

[0182] In the embodiments of the present application, the types and contents of the inorganic components / lithium salts in the electrolyte are well known in the art and can be detected using equipment and methods well known in the art. For example, the inorganic components / lithium salts in the electrolyte can be qualitatively or quantitatively analyzed by ion chromatography analysis method with reference to standard JY / T020-1996 "General Rules for Ion Chromatography Analysis Methods". In the embodiments of the present application, a 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 battery's state of charge is approximately 0% SOC) can be reversely disassembled, and the free electrolyte obtained from the battery can be used as a sample for detection using ion chromatography analysis method.

[0183] In the embodiment of the present application, the types and contents of the organic components in the electrolyte are well known in the art and can be detected using 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 perform qualitative and quantitative analysis of the organic components in the electrolyte by gas chromatography.

[0184] In the embodiment of the present application, after quantitative and qualitative detection of each component in the electrolyte, the components are classified, and the chain carboxylate solvent and carbonate solvent (such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate) are used as components of the organic solvent. The mass content of each component is calculated based on the mass of the electrolyte as 100%.

[0185] Carbonate additives (such as vinylene carbonate and fluoroethylene carbonate) and sulfur-containing additives are used as additives for the electrolyte. The mass content of each component is calculated based on the mass of the electrolyte being 100%.

[0186] [First pole piece and second pole piece]

[0187] like Figure 7 As shown, in some embodiments, the first pole piece 11 satisfies n*W1 / W2 of 0.5 to 1.0,

[0188] n represents the number of all the tabs on the same side of the coating portion;

[0189] W1 represents the average size of the pole ear along the length direction Z;

[0190] W2 represents the dimension of the coating portion along the length direction Z

[0191] Illustratively, n*W1 / W2 is 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, or a range consisting of any two of the above values.

[0192] The first pole piece 11 satisfies n*W1 / W2 of 0.5 to 1.0, so that the connection area between the pole ear and the coating portion is relatively large, and the flow area of ​​the pole ear is relatively large, which is beneficial to reducing DC resistance and reducing heat generation, thereby improving fast charging capability and high-temperature cycle performance.

[0193] W1 represents the average size of the first electrode tab 111 along the length direction Z,

[0194] When the first electrode tab 111 has a special-shaped structure, for example, along the width direction Y, the size of the first electrode tab 111 along the length direction Z gradually increases. In this case, the size of the first electrode tab 111 along the length direction Z at multiple locations can be measured to calculate the average size of the first electrode tab 111 along the length direction Z. Of course, the size of each location of the first electrode tab 111 along the length direction Z can be the same value, in which case this value can be used as the average size of the first electrode tab 111.

[0195] There may be one or more first pole tabs 111 , for example, n is 1 to 4. In the case of multiple first pole tabs 111 , the average size of each first pole tab 111 may be measured separately, and the sum of the average size values ​​may be divided by the number of first pole tabs 111 to calculate the average size of the first pole tabs 111 .

[0196] The first pole tab 111 is connected to the first coating portion 112, and the first pole tab 111 includes a first end 1111 connected to the first coating portion 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 tab 111 itself is relatively large, the contact area between the first pole tab 111 and the first coating portion 112 is relatively large, and the first pole tab 111 has a strong current-carrying capacity, which can improve the power performance and cycle performance of the battery cell 7.

[0197] Optionally, the first electrode tab 111 and the current collecting portion of the first coating portion 112 are an integrated structure, so that the internal resistance of the first electrode sheet 11 is low, which can further improve the power performance and cycle performance of the battery cell 7 .

[0198] Optionally, W2 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 a range consisting of any two of the above values.

[0199] Optionally, n*W1 is 150 mm to 650 mm, for example, 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 consisting of any two of the above values.

[0200] In some embodiments, the first electrode sheet 11 includes at least one first electrode tab 111 , and the at least one first electrode tab 111 is disposed on at least one side of the coating portion along the width direction Y.

[0201] like Figures 7 to 9 As shown, for example, at least one first pole ear 111 is arranged on one side of the coating portion along the width direction Y. In this case, it can be understood that all first pole ears 111 are arranged on the same side of the coating portion along the width direction Y. This arrangement is beneficial to increase the occupied space of the electrode assembly 10, thereby improving the energy density of the battery cell 7. Figure 7 In FIG, n is 1, W1 represents the size of a single first electrode tab 111 along the length direction Z; W2 represents the size of the first coating portion 112 along the length direction Z. Figure 8 In FIG, n is 4, the sizes of the first electrode tabs 111 are the same, and W1 represents the size of a single first electrode tab 111 along the length direction Z. Figure 9 In FIG, n is 1, W1 represents the dimension of a single first electrode tab 111 along the length direction Z, and n*W1 / W2 is 1.

[0202] like Figure 10 As shown, or for example, in the case where the first electrode sheet 11 includes a plurality of first electrode tabs 111 , the plurality of first electrode tabs 111 are disposed on both sides of the first coating portion 112 along the width direction Y.

[0203] Regardless of whether the first electrode tab 111 is disposed on one side or both sides of the first coating portion 112, there is at least one first electrode tab 111 located on the same side of the first coating portion 112 along the width direction Y. Optionally, there are at least two, for example, two, three, four, five, six, etc.; four is also optional. This arrangement facilitates uniform distribution of electrons on the first electrode sheet 11, thereby improving fast charging capability.

[0204] When there are at least two first electrode tabs 111 located on the same side of the first coating portion 112, the spacing between two adjacent first electrode tabs 111 along the length direction Z is greater than 0 and less than or equal to 300 mm, for example, 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 a range consisting of any two of the above values. Figure 10 Z1 shown in FIG. 1 represents the distance between two adjacent first electrode tabs 111 along the length direction Z.

[0205] When the distance between two adjacent first electrode tabs 111 along the length direction Z meets the above range, the migration path of electrons in the first coating portion 112 is shorter and can be evenly distributed, which is beneficial to improving the fast charging capability of the battery cell.

[0206] When multiple first tabs 111 are arranged 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 greater than 0 and less than or equal to 300 mm, for example, 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 a range consisting of any two of the above values. Figure 10 Y1 shown in FIG. 1 represents a dimension of the first coating portion 112 along the width direction Y. FIG.

[0207] When multiple first tabs 111 are arranged on one side of the first coating portion 112 along the width direction Y, the size of the first coating portion 112 along the width direction Y can be greater than 0 and less than or equal to 300 mm, for example, 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 a range consisting of any two of the above values.

[0208] When the dimension of the first coating portion 112 along the width direction Y meets the above requirements, the migration path of electrons in the width direction Y of the first coating portion 112 is shorter, and the electrons are evenly distributed in the first coating portion 112, which is beneficial to improving the fast charging capability of the battery cell.

[0209] like Figure 11 As shown, in some embodiments, the second pole piece 12 satisfies: m*W3 / W4 is 0.5 to 1.0;

[0210] m represents the number of all the tabs on the same side of the coating portion;

[0211] W3 represents the average size of the pole ear along the length direction Z;

[0212] W4 represents the dimension of the coating portion along the longitudinal direction Z.

[0213] Illustratively, m*W3 / W4 is 0.5, 0.55, 0.6, 2 / 3, 0.7, 0.75, 0.8, 0.85, 0.9, 1, or a range consisting of any two of the above values.

[0214] When m*W3 / W4 satisfies the above range, the flow area of ​​the second electrode tab 121 is relatively large, which is beneficial to improving the fast charging performance of the battery cell 7.

[0215] W3 represents the average size of the second pole tab 121 along the length direction Z. There may be one or more second pole tabs 121. For example, m is 1 to 4. When there are multiple second pole tabs 121, the size of each second pole tab 121 can be measured by a micrometer to calculate the average size.

[0216] The second pole tab 121 is connected to the second coating portion 122, and the second pole tab 121 includes a second end 1211 connected to the second coating portion 122. When m*W3 / W4 satisfies the above range, it means that the cross-section of the second end 1211 along the thickness direction of the second pole tab 121 itself is relatively large, and the contact area between the second pole tab 121 and the second coating portion 122 is relatively large. The second pole tab 121 has a strong current-carrying capacity, which can improve the power performance and cycle performance of the battery cell 7.

[0217] Optionally, the current collecting portion of the second electrode tab 121 and the second coating portion 122 is an integrated structure, so that the internal resistance of the second electrode sheet 12 is low, which can further improve the fast charging capability and cycle performance of the battery cell 7.

[0218] When the second pole piece 12 meets the above conditions, the connection area between the pole ear and the coating portion is relatively large, and the flow area of ​​the pole ear is relatively large, which is beneficial to reducing DC resistance and reducing heat generation, thereby improving fast charging capability and high-temperature cycle performance.

[0219] Optionally, W4 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 a range consisting of any two of the above values.

[0220] Optionally, m*W3 is 150 mm to 650 mm, for example, 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 consisting of any two of the above values.

[0221] In some embodiments, the second pole piece 12 includes at least one second pole tab 121 , and the at least one second pole tab 121 is disposed on at least one side of the coating portion along the width direction Y.

[0222] like Figure 12 As shown, for example, at least one second pole ear 121 is arranged on one side of the second coating portion 122 along the width direction Y. In this case, it can be understood that all second pole ears 121 are arranged on the same side of the second coating portion 122 along the width direction Y. This arrangement is beneficial to increase the occupied space of the electrode assembly 10, thereby improving the energy density of the battery cell 7.

[0223] Or for example, when the second electrode sheet 12 includes a plurality of second electrode tabs 121 , the plurality of second electrode tabs 121 are disposed on both sides of the second coating portion 122 along the width direction Y.

[0224] Regardless of whether the second electrode tab 121 is disposed on one side or both sides of the second coating portion 122, there is at least one second electrode tab 121 located on the same side of the second coating portion 122 along the width direction Y. Optionally, there are at least two second electrode tabs 121, such as two, three, four, five, six, etc.; four second electrode tabs may be optionally provided. This arrangement facilitates uniform distribution of electrons in the second electrode sheet 12, thereby improving fast charging capability.

[0225] When there are at least two second electrode tabs 121 located on the same side of the second coating portion 122, the spacing between two adjacent second electrode tabs 121 along the length direction Z is greater than 0 and less than or equal to 300 mm, for example, 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 a range consisting of any two of the above values.

[0226] When the distance between two adjacent second electrode tabs 121 along the length direction Z meets the above range, the migration path of electrons in the second coating portion 122 is shorter and can be evenly distributed, which is beneficial to improving the fast charging capability of the battery cell.

[0227] When multiple second tabs 121 are arranged on at least one side of the second coating portion 122 along the width direction Y, the dimension of the second coating portion 122 along the width direction Y is greater than 0 and less than or equal to 300 mm, for example, 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 a range consisting of any two of the above values.

[0228] When the size of the second coating portion 122 along the width direction Y meets the above requirements, the migration path of electrons in the width direction Y of the second coating portion 122 is shorter, and the electrons are evenly distributed in the second coating portion 122, which is beneficial to improving the fast charging capability of the battery cell.

[0229] When all second electrode tabs 121 are arranged on the same side of the second coating portion 122 along the width direction Y, and all first electrode tabs 111 are arranged on the same side of the first coating portion 112 along the width direction Y, the first electrode tabs 111 and the second electrode tabs 121 are respectively arranged on both sides of the coating portion along the width direction Y. This arrangement is more conducive to the connection between the same-polarity electrode tabs and the electrode terminals, and components with opposite polarities will not interfere with each other during assembly.

[0230] [Casing components]

[0231] In some embodiments, the battery cell 7 further includes a housing assembly 20 having a receiving space for receiving the electrode assembly 10 and the electrolyte.

[0232] In some embodiments, the housing assembly 20 includes a housing, a first electrode terminal 31 and a second electrode terminal 32 , and the first electrode terminal 31 and the second electrode terminal 32 are disposed on the housing.

[0233] The outer shell can be made of steel, aluminum, plastic (e.g., polypropylene), a composite metal shell (e.g., a copper-aluminum composite shell), or an aluminum-plastic film. In some embodiments, the outer shell can be either sealed or non-sealed. For example, in a non-sealed outer shell, the outer shell protects the electrode assembly 10 and includes a sealed bag between the outer shell and the electrode assembly 10, which encapsulates the electrode assembly 10 and the electrolyte. Specifically, the sealed bag can be a bag-shaped insulating member or an aluminum-plastic film. In a sealed outer shell, the sealed bag encapsulates the electrode assembly 10 and other components, such as the electrolyte.

[0234] 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 polygonal battery, and a polygonal battery such as a hexagonal battery. There is no special limitation in this application.

[0235] shell

[0236] In some embodiments, the housing includes an end cap 22 and a shell 21. The shell 21 has an opening, and the end cap 22 covers the opening. The shell 21 may have one or more openings. One or more end caps 22 may also be provided.

[0237] The first electrode terminal 31 and the second electrode terminal 32 may be provided on the housing 21 , or the first electrode terminal 31 and the second electrode terminal 32 may be provided on the end cover 22 . Alternatively, the first electrode terminal 31 and the second electrode terminal 32 may be provided on the end cover 22 .

[0238] The first electrode terminal 31 and the second electrode terminal 32 can be disposed on the same end cap 22. For example, there is one end cap 22, and the first electrode terminal 31 and the second electrode terminal 32 are disposed on the end cap 22 at intervals. In another example, there are two end caps 22, and the two end caps 22 are disposed opposite each other, and each end cap 22 is provided with a first electrode terminal 31 and a second electrode terminal 32.

[0239] The first electrode terminal 31 and the second electrode terminal 32 are respectively provided on different end covers 22 . For example, there are two end covers 22 , which are arranged opposite to each other. The first electrode terminal 31 is provided on one of the end covers 22 , and the second electrode terminal 32 is provided on the other end cover 22 .

[0240] The shape of the housing 21 can be determined based on the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 has a cylindrical structure, a cylindrical housing 21 can be selected; if the electrode assembly 10 has a rectangular parallelepiped structure, a rectangular parallelepiped housing 21 can be selected. Optionally, both the electrode assembly 10 and the housing 21 have rectangular parallelepiped structures.

[0241] In some embodiments, the housing 21 includes two first shell portions 211, a second shell portion 212, and a third shell portion 213. The two first shell portions 211 are opposite to each other along the thickness direction X of the battery cell 7, the second shell portion 212 and the third shell portion 213 are opposite to each other, and the second shell portion 212 and the third shell portion 213 are connected by the first shell portion 211. The second shell portion 212 includes a first wall 2121 and a second wall 2122 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 by tailor welding, laser welding, etc., and tailor welding can be selected. Since the area of ​​the second shell portion 212 is relatively small and the degree of expansion is relatively small, the weld is located on the second shell portion 212, which can reduce the risk of leakage of the battery cell 7.

[0242] When the battery cell 7 is assembled into the battery device's housing, it is placed within the housing, which includes a first housing portion and a second housing portion, with the first housing portion covering the second housing portion. The second housing portion 212 is positioned opposite the first housing portion, with the second housing portion 212 positioned adjacent to the first housing portion, and the third housing portion 213 positioned adjacent to the second housing portion. When the battery device is assembled into an electrical device, the first housing portion can be vertically positioned above the second housing portion. The second housing portion 212 has a weld seam, which faces upward, reducing the risk of leakage from the battery cell 7.

[0243] In some embodiments, the dimension of the battery cell 7 along the thickness direction X is 10 mm to 30 mm, for example, 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 a range consisting of any two of the above values.

[0244] The dimension of the battery cell 7 along the thickness direction X can represent the thickness of the battery cell 7. In other words, the thickness of the battery cell 7 is 10 mm to 30 mm. When the thickness of the battery cell 7 is within the above range, the thickness of the battery cell 7 is relatively small, which facilitates rapid heat dissipation within the battery cell 7 and reduces the risk of thermal runaway.

[0245] In some embodiments, the thickness of the housing 21 is 0.1 mm to 0.5 mm, for example, 0.1 mm, 0.12 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, 0.21 mm, 0.22 mm, 0.23 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0.30 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, 0.40 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, 0.50 mm, 0.51 mm, 0.52 mm, 0.53 mm, 0.54 mm, 0.55 mm, 0.56 mm, 0.57 mm, 0.58 mm, 0.59 mm, 0.60 mm, 0.61 mm, 0.62 mm, 0.63 mm, 0.64 mm, 0.65 mm, 0.66 mm, 0.67 mm, 0.68 mm, 0.69 mm, 0.70 mm, 3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, 0.4mm, 0.41mm, 0.42mm, 0.43mm, 0.44mm, 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.5mm, or a range consisting of any two of the above values. Optionally, the thickness of the housing 21 is 0.3mm to 0.4mm.

[0246] When the thickness of the shell 21 is within the above range, the shell 21 is relatively thin, which is conducive to rapid heat dissipation of the shell 21.

[0247] Exemplarily, the thickness of the first shell portion 211 is 0.1 mm to 0.5 mm, for example, 0.1 mm, 0.12 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, 0.21 mm, 0.22 mm, 0.23 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0. 3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, 0.4mm, 0.41mm, 0.42mm, 0.43mm, 0.44mm, 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.5mm, or a range consisting of any two of the above values. Optionally, the thickness of the housing 21 is 0.3mm to 0.4mm.

[0248] Exemplarily, the thickness of the second shell portion 212 is 0.1 mm to 0.5 mm, for example, 0.1 mm, 0.12 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, 0.21 mm, 0.22 mm, 0.23 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0. 3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, 0.4mm, 0.41mm, 0.42mm, 0.43mm, 0.44mm, 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.5mm, or a range consisting of any two of the above values. Optionally, the thickness of the housing 21 is 0.3mm to 0.4mm.

[0249] Exemplarily, the thickness of the third shell portion 213 is 0.1 mm to 0.5 mm, for example, 0.1 mm, 0.12 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, 0.21 mm, 0.22 mm, 0.23 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0. 3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, 0.4mm, 0.41mm, 0.42mm, 0.43mm, 0.44mm, 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.5mm, or a range consisting of any two of the above values. Optionally, the thickness of the housing 21 is 0.3mm to 0.4mm.

[0250] First electrode terminal

[0251] In some embodiments, the battery cell 7 further includes a first electrode terminal 31 , and the first electrode terminal 31 is connected to the first electrode tab 111 .

[0252] In some embodiments, there is at least one first electrode terminal 31 , and may be at least two, such as two, three, or four.

[0253] like Figure 13 As shown, in some embodiments, at least one first electrode terminal 31 is disposed on at least one side of the electrode assembly 10 along the width direction Y. This arrangement can shorten the migration path of electrons and is conducive to improving the fast charging capability.

[0254] For example, all the first electrode terminals 31 are disposed on one side of the electrode assembly 10 along the width direction Y.

[0255] For another example, the plurality of first electrode terminals 31 are disposed on both sides of the electrode assembly 10 along the width direction Y.

[0256] like Figure 14 As shown, in some embodiments, at least one first electrode terminal 31 is disposed on at least one side of the electrode assembly 10 along the length direction Z.

[0257] For example, all the first electrode terminals 31 are disposed on one side of the electrode assembly 10 along the length direction Z.

[0258] For another example, a plurality of first electrode terminals 31 are disposed on both sides of the electrode assembly 10 along the length direction Z. This arrangement can shorten the migration path of electrons, which is beneficial to improving the fast charging capability.

[0259] Exemplarily, there are two first electrode terminals 31, one of which 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. Alternatively, exemplary, there are four first electrode terminals 31, two of which are disposed on one side of the electrode assembly 10, and the other two are disposed on the other side of the electrode assembly 10.

[0260] The first electrode tab 111 is electrically connected to the first electrode terminal 31, either directly or indirectly. When the first electrode tab 111 is indirectly connected to the first electrode terminal 31, the battery cell 7 may include a first adapter 51, which is located between the first electrode terminal 31 and the first electrode tab 111 and connects the first electrode terminal 31 and the first electrode tab 111. If there are multiple first electrode tabs 111 and multiple first electrode terminals 31, the multiple first electrode tabs 111 may be divided into multiple groups, with each group of first electrode tabs 111 being connected to one first electrode terminal 31.

[0261] For example, when the first electrode terminal 31 is disposed on at least one side of the electrode assembly 10 along the longitudinal direction Z, and the first electrode tab 111 is disposed on at least one side of the first coating portion 112 along the width direction Y, the first adapter 51 facilitates the connection between the first electrode tab 111 and the first electrode terminal 31, while also improving the current carrying capacity of the battery cell 7. Disposing the first electrode terminal 31 on one side of the electrode assembly 10 along the longitudinal direction Z also increases the available space for the first electrode sheet 11 along the width direction Y, thereby increasing the energy density of the battery cell 7.

[0262] When the first pole tab 111 and the first electrode terminal 31 are respectively arranged 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 is connected to the first pole 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.

[0263] In the case where the first electrode 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 .

[0264] In the above embodiments, the first adapter 51 may be a sheet-like structure, and may also be other structural forms.

[0265] 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.

[0266] In some embodiments, the first tab 111 includes a first region connected to the first adapter 51 , and a ratio of a dimension of the first region along the length direction Z to a dimension of the first tab 111 along the length direction Z is 0.5 to 1.

[0267] Illustratively, the ratio of the dimension of the first region along the length direction Z to the dimension of the first tab 111 along the length direction Z is 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, or a range consisting of any two of the above values.

[0268] The dimension of the first region along the length direction Z is the distance between the first tab 111 and the first adapter 51, and this dimension can represent the current carrying capacity of the first tab 111. For example, when the first tab 111 and the first adapter 51 are welded, the first region is the weld mark area on the first tab 111.

[0269] When the first pole tab 111 meets the above conditions, the contact area between the first pole tab 111 and the first adapter 51 is relatively large. When welding is used, the welding area is relatively large, so that the first pole tab 111 has a stronger current-carrying capacity and a relatively low ohmic resistance, which is beneficial to improving the fast charging capability of the battery cell 7.

[0270] In some embodiments, the battery cell 7 also includes a first conductive member 61, which is located between the first adapter 51 and the first pole lug 111. The setting of the first conductive member 61 can increase the current flow capacity between the first pole lug 111 and the first adapter 51, which is beneficial to improving the fast charging performance, reducing heat generation, and improving the high-temperature cycle performance of the battery cell 7.

[0271] For example, the tab portion of the first electrode piece 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 .

[0272] Optionally, there are at least two first pole ears 111 located on the same side of the first coating portion 112, and at least two first conductive members 61. The first conductive members 61 and the first pole ears 111 are connected one-to-one, and 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.

[0273] like Figure 15 As shown, optionally, there are at least two first electrode tabs 111 located on the same side of the first coating portion 112 , and the first conductive member 61 may be a continuous sheet structure connecting at least two first electrode tabs 111 .

[0274] like Figure 16As shown, when the first tab 111 and the first electrode terminal 31 are respectively arranged on different sides of the battery cell 7, the first conductive member 61 optionally includes a first conductive portion 611 and a second conductive portion 612. The first conductive portion 611 extends along the length direction Z and 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 is connected to the first conductive portion 611. This structural arrangement is conducive to increasing the grouping space in the length direction Z and improving the energy density of the battery device.

[0275] It should be noted that, when the battery cell 7 does not include the first adapter 51 , the first electrode tab 111 may be connected to the first electrode terminal 31 through the first conductive member 61 .

[0276] Exemplarily, the first conductive member 61 has electrical conductivity, and 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.

[0277] In the embodiment of the present application, the first electrode terminal 31 can be an integrated structure, which can be integrally formed or connected to form an integrated structure by welding or other means. The integrated structure is beneficial to reducing resistance, reducing heat generation, and improving the power performance and cycle performance of the battery cell.

[0278] like Figures 17 to 19 As shown, in some embodiments, the first electrode terminal 31 may include a first electrode body 311 and a first electrode protrusion 312. The first electrode body 311 is located on the side of the end cap 22 facing the electrode assembly 10. The first electrode protrusion 312 is connected to the first electrode body 311 and protrudes toward the side away from the electrode assembly 10, and penetrates the end cap 22. Optionally, the first electrode body 311 and the first electrode protrusion 312 are an integrated structure. In other embodiments, the first electrode terminal 31 may include only the first electrode protrusion 312, which penetrates the end cap 22 and is connected to the electrode lug.

[0279] Optionally, the minimum cross-sectional area of ​​the first electrode protrusion 312 parallel to the thickness direction X is a first area, the area enclosed by the projected outer contour of the end cap 22 parallel to the thickness direction X is a second area, and the ratio of the first area to the second area is 0.02 to 0.20, for example, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20 or a range consisting 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. The first area refers to the minimum cross-sectional area of ​​the first electrode protrusion 312 of a single first electrode terminal 31. The first area is the overcurrent bottleneck of the first electrode terminal 31. When the first area meets the above conditions, the first electrode terminal 31 has a strong overcurrent capacity, which is beneficial to reducing heat generation and improving the fast charging performance and cycle performance of the battery cell.

[0280] The first electrode protrusion 312 can have multiple cross-sectional areas of different sizes along the thickness direction X. For example, if the first electrode protrusion 312 includes a first portion, a second portion, and a third portion connected in sequence, and the second portion has the smallest cross-sectional area, then the cross-sectional area of ​​the second portion is the first area. Of course, the cross-sectional area of ​​the first electrode protrusion 312 along the thickness direction X can also be the same at all locations.

[0281] Optionally, the ratio of the dimension of the first electrode protrusion 312 along the thickness direction X to the dimension of the end cap 22 along the thickness direction X 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 a range consisting of any two of the foregoing values. In this embodiment of the present application, the thickness direction X refers to the thickness direction X of the battery cell 7. The dimension of the first electrode protrusion 312 refers to the dimension of the first electrode protrusion 312 of a single first electrode terminal 31 along the thickness direction X. The dimension of the first electrode protrusion 312 along the thickness direction X can be understood as the width of the first electrode protrusion 312; the dimension of the end cap 22 along the thickness direction X can be understood as the width of the end cap 22.

[0282] When the first electrode protrusion 312 meets the above conditions, the size of the first electrode protrusion 312 is relatively high, which is beneficial to improving the current capacity of the first electrode terminal 31, thereby improving the fast charging performance.

[0283] In some embodiments, the housing assembly 20 further includes a first conductive fixing member 41. The first conductive fixing member 41 surrounds the first electrode terminal 31 and securely connects the first electrode terminal 31 to the end cap 22. At least a portion of the first conductive fixing member 41 is located on a side of the end cap 22 facing away from the electrode assembly 10. The first conductive fixing member 41 can be used to connect to an external busbar assembly. Optionally, an insulating member can be provided between the first conductive fixing member 41 and the end cap 22 for insulation.

[0284] The first conductive fixing member 41 can further increase the flow area between the battery cell 7 and the external bus assembly, thereby improving the flow capacity, which is beneficial to improving the flow capacity of the battery device and improving the fast charging performance of the battery device.

[0285] Optionally, a portion of the first electrode protrusion 312 protrudes from a side of the end cover 22 facing away from the electrode assembly 10 , and the first conductive fixing member 41 is disposed around the outside of the first electrode protrusion 312 .

[0286] Optionally, the ratio of the dimension of the first conductive fixing member 41 along the thickness direction X to the dimension of the end cap 22 along the thickness direction X is 0.40 to 0.80, for example, 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 a range consisting of any two of the foregoing values. In this embodiment of the present application, the thickness direction X refers to the thickness direction X of the battery cell 7. The dimension of the first conductive fixing member 41 refers to the dimension of a single first conductive fixing member 41 along the thickness direction X. Figure 18 X1 shown in the figure represents the dimension of the first conductive fixing member 41 along the thickness direction X, which can be understood as the width of the first conductive fixing member 41 ; X2 represents the dimension of the end cover 22 along the thickness direction X, which can be understood as the width of the end cover 22 .

[0287] When the first conductive fixing member 41 meets the above conditions, the size of the first conductive fixing member 41 is relatively high, which is beneficial to increasing the flow area between the battery cell 7 and the external bus assembly, thereby improving the flow capacity, which is beneficial to improving the flow capacity of the battery device and improving the fast charging performance of the battery device.

[0288] Second electrode terminal

[0289] In some embodiments, the battery cell further includes a second electrode terminal 32 , and the second electrode terminal 32 is connected to the second electrode tab 121 .

[0290] In some embodiments, there is at least one second electrode terminal 32 , and optionally at least two, such as two, three, or four.

[0291] 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 migration path of electrons and is conducive to improving the fast charging capability.

[0292] For example, all the second electrode terminals 32 are arranged 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 arranged on both sides of the electrode assembly 10 along the width direction Y, and will not interfere with each other when they are electrically connected to the electrode ear parts.

[0293] Exemplarily, there are two first electrode terminals 31 and two second electrode terminals 32 . The two first electrode terminals 31 are arranged on one side of the electrode assembly 10 along the width direction Y, and the two second electrode terminals 32 are arranged on the other side of the electrode assembly 10 along the width direction Y. Figure 13 FIG. 1 is a schematic diagram showing that the first electrode terminal 31 and the second electrode terminal 32 are disposed on both sides of the electrode assembly 10 along the width direction Y. FIG.

[0294] For another example, multiple second electrode terminals 32 are disposed on both sides of the electrode assembly 10 along the width direction Y. This arrangement can further shorten the electron migration path, which is conducive to improving the fast charging capability. 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.

[0295] 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.

[0296] For example, at least two second electrode terminals 32 are respectively provided on both sides of the electrode assembly 10 along the length direction Z. This arrangement can shorten the electron migration path and improve the fast charging capability. In this case, the first electrode terminal 31 and the second electrode terminal 32 are provided 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 provided on the other side of the electrode assembly 10 along the length direction Z.

[0297] For another example, there are two second electrode terminals 32, one of which 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 which 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. Figure 16 The battery cell 7 is shown to include four electrode terminals.

[0298] For another example, all the second electrode terminals 32 are arranged 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 arranged on both sides of the electrode assembly 10 along the length direction Z, and will not interfere with each other when they are electrically connected to the electrode ear parts.

[0299] like Figure 20 As shown, illustratively, there is one first electrode terminal 31 and one second electrode terminal 32, each located on either side of the electrode assembly along the length direction Z. The first electrode terminal 31 and the second electrode terminal 32 are staggered along the width direction Y. Specifically, when all second electrode tabs 121 are located on the same side of the second coating portion 122 along the width direction Y, and all first electrode tabs 111 are located on the same side of the first coating portion 112 along the width direction Y, the first electrode tab 111 and the second electrode tab 121 are located on either side of the coating portion along the width direction Y, with the first electrode terminal 31 located near the first electrode tab 111 and the second electrode terminal 32 located near the second electrode tab 121. This arrangement shortens the electron transmission distance and is more conducive to improving the fast charging capability of the battery cell 7.

[0300] The second electrode tab 121 is electrically connected to the second electrode terminal 32 , which may be directly or indirectly connected. When the second electrode tab 121 is indirectly connected to the second electrode terminal 32 , the battery cell 7 may include a second adapter, which is located between the second electrode terminal 32 and the second electrode tab 121 and connects the second electrode terminal 32 and the second electrode tab 121 .

[0301] For example, when the second electrode terminal 32 is disposed on at least one side of the electrode assembly 10 along the length direction Z, and the second electrode tab 121 is disposed on at least one side of the second coating portion 122 along the width direction Y, the second adapter facilitates the connection between the second electrode tab 121 and the second electrode terminal 32, while also improving the current carrying capacity of the battery cell 7. When the second electrode terminal 32 is disposed on one side of the electrode assembly 10 along the length direction Z, the space available for the second electrode sheet 12 along the width direction Y can be increased, thereby improving the energy density of the battery cell 7.

[0302] When the second pole lug 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 connecting portion and a second connecting portion, the first connecting portion extending along the length direction Z, the first connecting portion connected to the second pole lug 121, the second connecting portion connected to the first connecting portion and protruding from the first connecting portion along the width direction Y, and connected to the second electrode terminal 32.

[0303] In the case where the second electrode tab 121 and the second electrode terminal 32 are disposed on the same side of the battery cell 7 , the second adapter may include only the first connecting portion.

[0304] In the above embodiments, the second adapter may be a sheet-like structure, and may also be other structural forms.

[0305] In the above embodiments, the second transition component 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.

[0306] In some embodiments, the second tab 121 includes a second region connected to the second adapter, and a ratio of a dimension of the second region along the length direction Z to a dimension of the second tab 121 along the length direction Z is 0.5 to 1.

[0307] Illustratively, the ratio of the size of the second region along the length direction Z to the size of the second tab 121 along the length direction Z is 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, or a range consisting of any two of the above values.

[0308] The dimension of the second region along the length direction Z is the distance between the second tab 121 and the second adapter, which can represent the current carrying capacity of the second tab 121. For example, when the second tab 121 and the second adapter are welded, the first region is the weld mark area on the second tab 121.

[0309] When the second electrode tab 121 meets the above conditions, the second electrode tab 121 has a strong current-carrying capacity, which is beneficial to improving the fast charging capability of the battery cell 7 .

[0310] 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 flow capacity between the second tab 121 and the second adapter, thereby improving fast charging performance and reducing heat generation. Furthermore, the second tab 121 and the second adapter, as well as the second conductive member and the second adapter, can be electrically connected via welding. The presence of the second conductive member can significantly reduce the risk of failure caused by direct electrical connection between multiple second tabs 121 and the second adapter.

[0311] For example, the pole tab portion of the second pole piece 12 is arranged 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 pole tab 121 and connects the second adapter and the second pole tab 121 .

[0312] Optionally, there are at least two second pole ears 121 located on the same side of the second coating portion 122, and the second conductive member can be a continuous sheet structure, connecting at least two second pole ears 121; or there are at least two second conductive members, the second conductive members and the second pole ears 121 are connected one-to-one, 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.

[0313] When the second electrode tab 121 and the second electrode terminal 32 are respectively arranged on different sides of the battery cell 7, the second conductive member can optionally include a third conductive portion and a fourth conductive portion. The third conductive portion extends along the length direction Z and connects the electrode tab of the second electrode sheet 12 to 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. The third conductive portion is connected to the second adapter. This structural arrangement is conducive to increasing the grouping space in the length direction Z and improving the energy density of the battery device.

[0314] Exemplarily, the second conductive member has electrical conductivity, and 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.

[0315] It should be noted that, when the battery cell 7 does not include the second adapter, the second electrode tab 121 can be connected to the second electrode terminal 32 through the second conductive member.

[0316] In the embodiment of the present application, the second electrode terminal 32 can be an integrated structure, which can be integrally formed or connected to form an integrated structure by welding or other means. The integrated structure is beneficial to reducing resistance, reducing heat generation, and improving the power performance and cycle performance of the battery cell.

[0317] For example, in some embodiments, the structure of the second electrode terminal 32 is similar to that of the first electrode terminal 31. For example, the second electrode terminal 32 may include a second electrode body and a second electrode protrusion. The second electrode body is located on the side of the end cap 22 facing the electrode assembly 10. The second electrode protrusion is connected to the second electrode body and protrudes toward the side away from the electrode assembly 10, and penetrates the end cap 22. Optionally, the second electrode body and the second electrode protrusion are an integrated structure. In other embodiments, the second electrode terminal 32 may include only the second electrode protrusion, which penetrates the end cap 22 and is connected to the electrode lug.

[0318] In some embodiments, the housing assembly 20 further includes a second conductive fixing member that surrounds the second electrode terminal 32 and securely connects the second electrode terminal 32 to the end cap 22. The structure and dimensions of the second conductive fixing member are similar to those described for the first conductive fixing member 41.

[0319] The second conductive fixing member can further increase the flow area between the battery cell 7 and the external bus assembly, thereby improving the flow capacity, which is beneficial to improving the flow capacity of the battery device and improving the fast charging performance of the battery device.

[0320] Heat conduction components

[0321] In some embodiments, the battery cell 7 further includes a heat conduction component, which is disposed between the pole ear portion and the coating portion. The heat conduction component can conduct the heat generated by the pole ear portion, quickly transfer the heat generated by the pole ear portion, and reduce the risk of heat-induced ablation of the isolation member in the electrode assembly.

[0322] Optionally, the pole ear portion is arranged on at least one side of the coating portion along the width direction of the battery cell, and the pole ear portion extends along the length direction and has a gap with the coating portion; the battery cell further includes a heat conduction component, which is at least arranged in the gap.

[0323] Optionally, the heat conducting member is further in contact with the housing 21 , so as to diffuse heat from the housing 21 .

[0324] like Figure 21 As shown, exemplarily, the heat conducting member includes a first heat conducting member 81 , which is disposed in a gap between the first electrode tab 111 and the first coating portion 112 . The first heat conducting member 81 can conduct heat generated by the first electrode tab 111 .

[0325] Optionally, the first heat conduction member 81 may be further arranged in the gap between the first electrode tab 111 and the first electrode terminal 31. When the battery cell 7 includes a first adapter 51, the first heat conduction member 81 may also be arranged in the gap between the first electrode tab 111 and the first adapter 51, or in the gap between the second adapter portion 512 and the coating portion of the first adapter 51.

[0326] Exemplarily, the heat conducting member includes a second heat conducting member disposed in a gap between the second electrode tab 121 and the second coating portion 122 , and the second heat conducting member can conduct heat generated by the second electrode tab 121 .

[0327] Optionally, the second heat conducting member may be further provided in the gap between the second electrode tab 121 and the second electrode terminal 32 . In the case where the battery cell 7 includes a second adapter, the second heat conducting member may be further provided in the gap between the second electrode tab 121 and the second adapter.

[0328] The main material of the heat conduction component includes one or more of polyimide PI and polyethylene terephthalate PET.

[0329] Positive electrode

[0330] In order to explain the present application more clearly, the coating portion of the positive electrode sheet corresponds to the positive electrode coating portion, the ear portion corresponds to the positive electrode 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 collecting portion and a positive electrode film layer arranged on at least one side of the positive electrode current collecting portion.

[0331] The positive electrode sheet includes a positive current collector and a positive electrode film layer comprising a positive electrode active material and disposed on at least one surface of the positive current collector. For example, the positive current collector may have two opposing surfaces in the thickness direction of the positive current collector, and the positive electrode film layer may be disposed on one or both of the two opposing surfaces of the positive current collector.

[0332] The upper limit voltage for charging and the cut-off voltage for discharging of the battery cell vary depending on the different positive electrode active materials. For example, when the phosphate material includes lithium iron phosphate, the upper limit voltage for charging may be 3.65V and the cut-off voltage for discharging may be 2.0V, or the upper limit voltage for charging may be 3.8V and the cut-off voltage for discharging may be 2.0V. For another example, when the phosphate material includes lithium manganese iron phosphate, the upper limit voltage for charging may be 4.3V and the cut-off voltage for discharging may be 2.0V. Next, taking the upper limit voltage for charging of 3.65V and the cut-off voltage for discharging of 2.0V as an example, the state of the battery cell is 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:

[0333] The battery cell is charged at a constant current charge rate of 0.33C to the upper limit of the charge voltage, and then charged at a constant voltage to 0.05C, corresponding to the state of 100% SOC of the battery cell. The battery cell is discharged at a constant current discharge rate of 0.33C to the cut-off voltage, corresponding to the state of 0% SOC of the battery cell.

[0334] In some embodiments, the compaction density of the positive electrode film layer of the battery cell at 0% state of charge SOC is 2.30 g / cm 3 to 2.70g / cm 3 ; Optional 2.40g / cm 3 Up to 2.55g / cm 3 For example, when the battery cell is at 0% state of charge (SOC), the compaction density of the positive electrode film is 2.30 g / cm 3 , 2.32g / cm 3 , 2.35g / cm 3 , 2.38g / cm 3 , 2.40g / cm 3 , 2.42g / cm 3 , 2.45g / cm3 , 2.48g / cm 3 , 2.50g / cm 3 , 2.52g / cm 3 , 2.55g / cm 3 , 2.56g / cm 3 , 2.57g / cm 3 , 2.58g / cm 3 , 2.60g / cm 3 , 2.62g / cm 3 , 2.65g / cm 3 , 2.68g / cm 3 , 2.70g / cm 3 Or a range consisting of any two of the above values.

[0335] 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 material of the positive electrode film layer is stacked relatively densely, the contact resistance between particles is small, which can further reduce the resistance of the electrode sheet, thereby reducing heat generation under fast charging, alleviating the problem of aggravated side reactions on the negative electrode side due to heat accumulation, and improving the cycle performance of the battery cell.

[0336] In some embodiments, the single-sided coating weight of the positive electrode film layer is 250 mg / 1540.25 mm 2 Up to 330mg / 1540.25mm 2 , optional 275mg / 1540.25mm 2 Up to 300mg / 1540.25mm 2 For example, the coating weight of the positive electrode film on one side is 250 mg / 1540.25 mm 2 、260mg / 1540.25mm 2 、270mg / 1540.25mm 2 、280mg / 1540.25mm 2 、290mg / 1540.25mm 2 、300mg / 1540.25mm 2 、310mg / 1540.25mm 2 、320mg / 1540.25mm 2 、330mg / 1540.25mm 2 Or a range consisting of any two of the above values.

[0337] When the single-sided coating weight of the positive electrode film layer is within the above range, the heat generated per unit area of ​​the positive electrode sheet will not be too large, thereby alleviating the problem of aggravated side reactions on the negative electrode side due to heat accumulation, improving the cycle performance of the battery cell, and increasing the energy density of the battery cell.

[0338] In the embodiments of the present application, the compacted density of the positive electrode film layer of a battery cell at 0% state of charge (SOC) has a meaning well known in the art. Specifically, the positive electrode sheet of a battery cell at 0% state of charge (SOC) is disassembled and the compacted density of the positive electrode film layer is measured. For example, a single-sided coated positive electrode sheet (if a double-sided coated sheet, the positive electrode film layer on one side can be wiped off first) is punched into small discs with an area of ​​S1. The discs are weighed and recorded as M1, and their thickness H1 is measured. The positive electrode film layer of the weighed positive electrode sheet is then wiped off, and the weight of the positive current collector is weighed and recorded as M0, and its thickness H0 is measured. The single-sided coating weight of the positive electrode film layer = (weight of the positive electrode sheet M1 - weight of the positive current collector M0) / S1. The thickness of the positive electrode film layer = thickness of the positive electrode sheet H1 - thickness of the positive current collector H0. The compacted density of the positive electrode film layer = single-sided coating weight of the positive electrode film layer / thickness of the positive electrode film layer.

[0339] In some embodiments, the positive electrode active material includes a lithium-containing phosphate with an olivine structure. In other embodiments, the positive electrode active material may also include a lithium-containing transition metal oxide, 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 modified compounds thereof.

[0340] In the embodiment of the present application, the lithium-containing phosphate with an olivine structure can be phosphate particles, or a material obtained by coating and modifying the phosphate particles. For example, the lithium-containing phosphate with an olivine structure includes phosphate particles and a coating layer. The coating layer is coated on the surface of the phosphate particles. For example, the coating layer includes elements such as carbon, which improves the conductivity of the phosphate particles, reduces the powder resistivity of the material, and is beneficial to the migration rate of lithium ions, thereby improving the fast charging capability of the battery and reducing the heat generation of the battery cell.

[0341] In some embodiments, the phosphate particles include a general formula of Li x1 A y1 Me a M b P 1-c X c Y zCompounds wherein 0.5≤x1≤1.3, 0≤y1≤1.3, and 0.9≤x1+y1≤1.3, 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5, 0≤c≤0.5, 3≤z≤5, A comprises one or more of Na, K, and Mg, Me comprises one or more of Mn, Fe, Co, and Ni, M comprises 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 comprises one or more of Cl, C, and N, and Y comprises one or more of O and F. The phosphate particles have excellent cycling stability, which is beneficial for improving the cycling performance of battery cells.

[0342] Exemplarily, the phosphate particles include one or more of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4. The battery cells are accompanied by the deintercalation and consumption of active ions such as Li during the charge and discharge process, and the molar content of Li in the battery cells is different when discharged to different states. In the enumeration of positive electrode active materials LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, etc., the molar content of Li is the initial state of the material, that is, the state before feeding. The positive electrode active material is used in the battery system, and the molar content of Li may change after charge and discharge cycles. In the enumeration of positive electrode active materials LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, etc. in the embodiment of the present application, the molar content of oxygen O is only a theoretical state value. Lattice oxygen release will cause the molar content of oxygen O to change. In practice, the molar content of oxygen O will fluctuate. The above situations are all within the scope of protection of this application.

[0343] In the embodiments of this application, the element content in the positive electrode active material has a meaning well known in the art and can be measured using equipment and methods well known in the art. For example, in accordance with EPA 6010D-2014, it can be measured by inductively coupled plasma atomic emission spectrometry (ICP-OES, instrument model: Thermo ICAP7400). After discharging the battery cell to 0% state of charge (SOC), the positive electrode sheet is disassembled, cleaned with dimethyl carbonate (DMC), dried, and calcined at high temperature to remove impurities. Then, 0.4g of the positive electrode active material is weighed and 10ml (50% concentration) of aqua regia is added. The sample is then placed on a plate at 180°C for 30 minutes. After digestion on the plate, the volume is adjusted to 100ml, and quantitative analysis is performed using a standard curve method.

[0344] In some embodiments, the positive electrode film layer further includes a positive electrode additive, which includes lithium element and can release lithium ions during the charging process of the battery cell to compensate for lithium loss, thereby improving the capacity characteristics and cycle performance of the battery cell.

[0345] In some embodiments, the positive electrode additive includes at least one of lithium ferrite particles or lithium nickelate particles.

[0346] In some embodiments, the average longest diameter of the positive electrode additive is 2 μm to 5 μm, such as 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, or any combination thereof. When positive electrode additives having such particle sizes are used, the stability of the positive electrode additive can be effectively improved while also achieving a good lithium replenishment effect.

[0347] In the embodiments of the present application, the positive electrode sheet is cut along its thickness to expose a longitudinal section of the positive electrode film layer. The longitudinal section of the positive electrode film layer is then subjected to scanning electron microscopy (SEM) to determine the longest diameter of the positive electrode additive particles. For example, the "longest diameter" of a particle refers to the longest straight line extending through the center of the particle and to the particle's periphery.

[0348] In a cross section of the positive electrode film along its own thickness direction, the longest diameters of a plurality of, for example, 10, lithium-containing iron oxides are counted, and the average value thereof is calculated as the average longest diameter.

[0349] In some embodiments, based on the total mass of the positive electrode film layer, the mass proportion of the positive electrode additive is 0.2% to 2.5%, for example, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.5% or a range consisting of any two thereof.

[0350] When a range of positive electrode additives are used, lithium loss can be effectively compensated.

[0351] In some embodiments, the positive electrode film layer may further optionally include a positive electrode conductive agent. The present application does not particularly limit the type of positive electrode conductive agent. For example, the positive electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass content of the positive electrode conductive agent is ≤5% based on the mass of the positive electrode film layer.

[0352] In some embodiments, the positive electrode film layer may further optionally include a positive electrode binder. The embodiments of the present application do not particularly limit the type of positive electrode binder. As an 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 fluorine-containing acrylic resin. In some embodiments, based on the mass of the positive electrode film layer, the mass content of the positive electrode binder is ≤5%.

[0353] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. Examples of metal foils include at least one of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. For example, the metal layer may include at least one of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0354] In some embodiments, the ratio of the thickness of the positive electrode film layer on a single side to the thickness of the positive electrode current collector is 3 to 10, for example, 3, 4, 5, 6, 7, 8, 9, 10, or a range consisting of any two of the foregoing values. Alternatively, the ratio of the thickness of the positive electrode film layer on a single side to the thickness of the positive electrode current collector is 4 to 8.

[0355] When the ratio of the thickness of the single-sided positive electrode film layer to the thickness of the positive electrode current collecting portion is within the above range, the fast charging capability and energy density of the battery cell can be improved.

[0356] In some embodiments, the thickness of the positive electrode current collector is 12 μm to 16 μm, optionally 13 μm to 15 μm. For example, the thickness of the positive electrode current collector is 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, or a range consisting of any two of the above values.

[0357] When the thickness of the positive electrode current collecting portion is within the above range, the positive electrode current collecting portion has a relatively excellent current flow capacity and can enable the battery cell to have a relatively high energy density.

[0358] In the embodiment of the present application, the thickness of the positive electrode film layer and the positive electrode current collecting portion has a meaning well known in the art and can be detected by using equipment and methods well known in the art. For example, the thickness of the positive electrode sheet is measured using a micrometer, the film layer on the surface of the positive electrode current collecting portion is removed, and the thickness of the positive electrode current collecting portion is measured using 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 electrode current collecting 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 electrode current collecting portion) / 2.

[0359] The positive electrode film is typically formed by coating a positive electrode slurry onto the positive electrode current collector, drying it, and cold pressing it. The positive electrode slurry is typically formed by dispersing the positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent and stirring them uniformly. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP).

[0360] The positive electrode sheet does not exclude other additional functional layers in addition to 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 electrode current collector and the positive electrode film layer and disposed on the surface of the positive electrode current collector. In 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.

[0361] Negative electrode

[0362] In order to explain the present application more clearly, the coating portion of the negative electrode sheet corresponds to the negative electrode coating portion, the ear portion corresponds to the negative electrode ear, the active material layer corresponds to the negative electrode film layer containing the negative electrode active material, the negative electrode coating portion includes a negative electrode current collecting portion and a negative electrode film layer arranged on at least one side of the negative electrode current collecting portion, and the negative electrode coating portion includes a negative electrode current collecting portion and a negative electrode film layer arranged on at least one side of the negative electrode current collecting portion.

[0363] The negative electrode sheet includes a negative current collector and a negative electrode film layer comprising a negative electrode active material disposed on at least one surface of the negative current collector. For example, the negative current collector may have two opposing surfaces in the thickness direction of the negative current collector, and the negative electrode film layer may be disposed on either or both of the two opposing surfaces of the negative current collector.

[0364] In some embodiments, the compaction density of the negative electrode film layer of the battery cell at 0% state of charge (SOC) is 1.30 g / cm 3 Up to 1.65g / cm 3 ; Optional 1.35g / cm 3 Up to 1.50g / cm 3 For example, the compaction density of the negative electrode film layer of the battery cell at 0% state of charge is 1.3 g / cm 3 , 1.32g / cm 3, 1.35g / cm 3 , 1.40g / cm 3 , 1.45g / cm 3 , 1.50g / cm 3 , 1.55g / cm 3 , 1.60g / cm 3 , 1.65g / cm 3 Or a range consisting of any two of the above values.

[0365] 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 material of the negative electrode film layer is stacked relatively densely, the contact resistance between particles is small, which can further reduce the resistance of the electrode sheet, thereby reducing heat generation, alleviating the problem of aggravated side reactions on the negative electrode side due to heat accumulation, and improving the cycle performance of the battery cell.

[0366] In the embodiment of the present application, the compaction density of the negative electrode film layer of the battery cell at 0% state of charge SOC has a meaning well known in the art and can be detected using equipment and methods well known in the art, and its detection method is the same as the compaction density test method of the positive electrode film layer mentioned above.

[0367] In some embodiments, the single-sided coating weight of the negative electrode film layer is 120 mg / 1540.25 mm 2 Up to 180mg / 1540.25mm 2 , optional 125mg / 1540.25mm 2 Up to 150mg / 1540.25mm 2 For example, the coating weight of the negative electrode film on one side is 120 mg / 1540.25 mm 2 、122mg / 1540.25mm 2 、125mg / 1540.25mm 2 、128mg / 1540.25mm 2 、130mg / 1540.25mm 2 、132mg / 1540.25mm 2 、135mg / 1540.25mm 2 、137mg / 1540.25mm 2 、140mg / 1540.25mm 2 、145mg / 1540.25mm 2 、150mg / 1540.25mm 2 、155mg / 1540.25mm 2 、160mg / 1540.25mm 2、165mg / 1540.25mm 2 、170mg / 1540.25mm 2 、175mg / 1540.25mm 2 、180mg / 1540.25mm 2 Or a range consisting of any two of the above values.

[0368] When the single-sided coating weight of the negative electrode film layer is within the above range, the heat generated per unit area of ​​the negative electrode sheet will not be too large, thereby alleviating the problem of aggravated side reactions on the negative electrode side due to heat accumulation, improving the cycle performance of the battery cell, and being able to simultaneously improve the energy density of the battery cell.

[0369] In the embodiment of the present application, the single-sided coating weight of the negative electrode film layer has a meaning well known in the art and can be detected using equipment and methods well known in the art, such as the single-sided coating weight test method of the film layer described above.

[0370] In some embodiments, the negative electrode active material includes a carbon-based material, which has high cycling stability and can improve the cycling performance of the battery cell. The positive electrode active material of this application is primarily an olivine-structured lithium-containing phosphate system, and the negative electrode active material is primarily a carbon-based material system. The combination of the two results in excellent cycling performance for the battery cell.

[0371] Optionally, the carbon-based material includes artificial graphite, which has excellent electrical conductivity, can reduce the heat generation of the negative electrode plate, reduce the heat generation of the battery cell, and improve the fast charging performance of the battery cell.

[0372] In some embodiments, the carbon-based material may also include natural graphite. Specifically, the carbon-based material may include artificial graphite, or the carbon-based material may include both artificial and natural graphite. Natural graphite has relatively good electrical conductivity, which further reduces heat generation and improves the power performance and cycle performance of the battery cell.

[0373] In some embodiments, the negative electrode active material may include at least one of a tin-based material and lithium titanate, in addition to the aforementioned carbon-based material and optionally a silicon-based material. The tin-based material may include at least one of elemental tin, tin oxide, and a tin alloy. Alternatively, the silicon-based material may include at least one of elemental silicon, silicon oxide, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy.

[0374] The qualitative and quantitative properties of each substance or element in this application can be detected using appropriate equipment and methods known to those skilled in the art. The relevant detection methods can refer to domestic and international detection standards, domestic and international enterprise standards, etc., and those skilled in the art can also adapt certain detection steps / instrument parameters, etc. from the perspective of detection accuracy to obtain more accurate detection results. A single detection method can be used for qualitative or quantitative determination, or several detection methods can be used in combination for qualitative or quantitative determination.

[0375] For example, the present application may combine JIS / K0131-1996 General Rules for X-ray Diffraction Analysis Methods to perform X-ray powder diffraction testing and qualitative analysis on the negative electrode sheet or negative electrode active material.

[0376] Artificial graphite and natural graphite can be distinguished by the SEM cross-section taken by a scanning electron microscope (SEM). The SEM cross-section of natural graphite shows gaps between the flake structures, while the SEM cross-section of artificial graphite is dense and has no obvious gaps. They can also be distinguished by the XRD spectrum obtained by the X-ray diffraction method. The XRD spectrum of natural graphite shows obvious 2H phase and 3R phase, while the XRD spectrum of artificial graphite only shows 2H phase.

[0377] In the embodiment of the present application, the negative electrode film layer includes at least one film layer, which can be a single film layer or at least two film layers. Optionally, the negative electrode film layer includes at least two film layers.

[0378] In the case where the negative electrode film layer adopts a single-layer film layer, the negative electrode active material in the negative electrode film layer includes a carbon-based material. In the case of a single-layer film layer, the volume average particle size Dv50 of the carbon-based material is 8μm to 13μm, and can be optionally 9.5μm to 11.5μm. Exemplarily, the volume average particle size Dv50 of the carbon-based material is 8μm, 8.5μm, 8.8μm, 9μm, 9.2μm, 9.5μm, 9.8μm, 10μm, 10.2μm, 10.5μm, 10.8μm, 11μm, 11.2μm, 11.5μm, 11.8μm, 12μm, 12.2μm, 12.5μm, 12.8μm, 13μm or a range consisting of any two of the above values.

[0379] In the case where the negative electrode film layer comprises at least two film layers, the negative electrode active material in the negative electrode film layer comprises a carbon-based material. The negative electrode film layer may comprise two film layers, three film layers, four film layers, or even more film layers.

[0380] 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 being disposed on a surface of a negative electrode current collector, the carbon-based material of the first negative electrode film layer including artificial graphite, the second negative electrode film layer being connected to a side of the first negative electrode film layer facing away from the negative electrode current collector, the carbon-based material of the second negative electrode film layer including artificial graphite, and 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, they may have different particle sizes or different degrees of graphitization.

[0381] The interface between the first negative electrode film layer and the second negative electrode film layer may be regular or irregular, and may optionally be irregular.

[0382] The negative electrode film comprises at least two layers, and layered coating can improve the rapid charging performance of the battery cell. In particular, when the first and second negative electrode film layers are different, the pores of the negative electrode film layers can be differentiated, reducing the tortuosity of lithium-ion transport and improving the rapid charging performance of the battery cell.

[0383] 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 dynamic performance of the negative electrode film layer.

[0384] There is a difference in the particle size 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 higher, and the bottleneck of fast charging mainly lies in the second negative electrode film layer. In the embodiment 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 improve the problem of lithium plating on the surface of the negative electrode sheet, thereby improving the cycle performance of the battery cell.

[0385] Optionally, the carbon-based material of the first negative electrode film layer is granular, and its volume average particle size Dv50 is 9.0 μm to 18.5 μm, and optionally 9.0 μm to 14.6 μm. Exemplarily, the volume average particle size of the carbon-based material of the second negative electrode film layer 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 consisting 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 9.0 μm to 18.5 μm, and optionally 9.0 μm to 14.6 μm.

[0386] 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 easy to agglomerate during the preparation process, which can improve the stability of the material.

[0387] Optionally, 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, and optionally 7.8 μm to 11.3 μm. Exemplarily, the volume average particle size Dv50 of the carbon-based material is 7.8μm, 8.0μm, 8.2μm, 8.5μm, 8.8μm, 9μm, 9.2μm, 9.5μm, 9.8μm, 10μm, 10.2μm, 10.5μm, 10.8μm, 11μm, 11.3μm, 11.2μm, 11.5μm, 11.8μm, 12μm, 12.2μm, 12.5μm, 12.8μm, 13μm, 13.2μm, 13.5μm, 13.8μm, 14μm, 14.1μm, 14.3μm or a range consisting 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 7.8 μm to 14.3 μm, and optionally 7.8 μm to 11.3 μm.

[0388] When the volume average particle size Dv50 of the carbon-based material of the second 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.

[0389] 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 easy to agglomerate during the preparation process, which can improve the stability of the material; on the other hand, the combination of the negative electrode active material in the second negative electrode film layer within the above volume average particle size range and the negative electrode active material in the first negative electrode film layer is beneficial to constructing a 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.

[0390] In the embodiment of the present application, the volume average particle size Dv50 of the negative electrode active material has a meaning well known in the art and can be detected using equipment and methods well known in the art. For example, the negative electrode active material is used as a sample and the Dv50 of the particles is tested using a Mastersizer 2000E laser particle size analyzer in accordance with the test standard GB / T 19077-2016.

[0391] Optionally, the carbon-based material of the first negative electrode film layer further includes natural graphite.

[0392] Illustratively, 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.

[0393] In 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 is greater than the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer, which is beneficial to improving the compaction density of the negative electrode film layer.

[0394] The difference in particle size between the first negative electrode film layer and the second negative electrode film layer can improve the fast charging performance of the battery cell.

[0395] Optionally, the carbon-based material of the second negative electrode film layer is granular, and its volume average particle size Dv50 is 9.0 μm to 18.5 μm, and optionally 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, the solid-phase transmission path of lithium ions can be shortened, thereby improving the fast charging performance. On the other hand, the material is less likely to agglomerate during the preparation process, thereby improving the stability of the material.

[0396] 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 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, thereby improving fast charging performance.

[0397] Illustratively, 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.

[0398] In some embodiments, the negative electrode film layer may further optionally include a negative electrode conductive agent. The present application does not particularly limit the type of negative electrode conductive agent. For example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the weight content of the negative electrode conductive agent is ≤5% based on the total weight of the negative electrode film layer.

[0399] In some embodiments, the negative electrode film layer may further include a negative electrode binder. In some embodiments, the negative electrode binder has a mass content of ≤5% based on the total weight of the negative electrode film layer.

[0400] In some embodiments, the negative electrode film layer may also optionally include other additives. Examples of these additives include thickeners, dispersants, and the like, such as sodium carboxymethylcellulose (CMC-Na) and PTC thermistor materials. In some embodiments, the weight content of these additives is ≤ 2% based on the total weight of the negative electrode film layer.

[0401] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. Examples of metal foils include at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. For example, the metal layer may include at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0402] In some embodiments, the ratio of the thickness of the negative electrode film layer on one side to the thickness of the negative electrode current collector is 8 to 14, such as 8, 9, 10, 11, 12, 13, 14, or a range consisting of any two of the foregoing values. Alternatively, the ratio of the thickness of the negative electrode film layer on one side to the thickness of the negative electrode current collector is 10 to 12.

[0403] When the ratio of the thickness of the single-side negative electrode film layer to the thickness of the negative electrode current collecting portion is within the above range, the fast charging capability and energy density of the battery cell can be improved.

[0404] In some embodiments, the thickness of the negative electrode current collector is 5 μm to 10 μm, optionally 6 μm to 8 μm. For example, 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 a range consisting of any two of the above values.

[0405] When the thickness of the negative electrode current collecting portion is within the above range, the negative electrode current collecting portion has a relatively excellent current flow capacity and can enable the battery cell to have a relatively high energy density.

[0406] In the embodiment of the present application, the thickness of the negative electrode current collector has a meaning well known in the art and can be detected using equipment and methods well known in the art. For example, a solvent is used to wash away the film layer on the surface of the negative electrode current collector, and the thickness of the negative electrode current collector is measured with a micrometer.

[0407] The negative electrode film layer is typically formed by coating the negative electrode slurry onto the negative electrode current collector, drying it, and cold pressing it. The negative electrode slurry is typically formed by dispersing the negative electrode active material, an optional conductive agent, an optional binder, and other optional additives in a solvent and stirring them uniformly. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0408] The negative electrode sheet does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode sheet of the embodiments of the present application further includes a negative 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 sheet of the embodiments of the present application further includes a protective layer covering the surface of the negative electrode film layer.

[0409] [Isolator]

[0410] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode sheet and the negative electrode sheet.

[0411] In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical and mechanical stability can be selected.

[0412] As an example, the primary material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. 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 separate component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes. The surface of the separator can also be coated with an inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating.

[0413] In some embodiments, the volumetric energy density of the battery cell is 380Wh / L to 450Wh / L. For example, the volumetric energy density of the battery cell is 380Wh / L, 395Wh / L, 400Wh / L, 410Wh / L, 420Wh / L, 430Wh / L, 450Wh / L, or a range consisting of any two of the foregoing values.

[0414] In the embodiments of the present application, the volume energy density of a battery cell has a meaning well known in the art and can be detected using equipment and methods well known in the art. For example, the battery charging upper limit voltage is 3.65V and the battery discharge cut-off voltage is 2.0V.

[0415] Place the battery cell at 25°C, charge at a constant current of 0.33C to 3.65V, then charge at a constant voltage to 0.05C, and discharge at a constant current of 0.33C to 2.0V. Record the discharge capacity A0 at this time, unit: Ah. Use calipers to measure the length, width, and height of the battery cell (generally calculated based on the battery casing size, excluding the electrode terminal height and the insulating film outside the casing), calculate the volume of the single battery V0, unit L, and the volume energy density of the battery cell VED = (A0 × discharge platform voltage) / V0, unit Wh / L.

[0416] Example

[0417] The following examples describe the disclosure of the present invention in more detail. These examples are intended for illustrative purposes only, as various modifications and variations within the scope of the disclosure of the present invention will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0418] Example 1

[0419] 1. Preparation of positive electrode sheet

[0420] The positive electrode sheet includes a positive electrode tab, a positive electrode current collecting part and a positive electrode film layer arranged on both sides of the positive electrode current collecting part. The positive electrode current collecting part is an aluminum foil with a thickness of 13μm.

[0421] The positive electrode film layer includes lithium iron phosphate, a lithium-containing phosphate with a mass ratio of 96:1:2:1, lithium ferrite, a positive electrode additive, polyvinylidene fluoride (PVDF), a binder, and acetylene black, a conductive agent. The positive electrode film layer is formed by evenly coating the positive electrode slurry (the solvent is N-methylpyrrolidone NMP) on both sides of the positive electrode current collecting part, and then drying and cold pressing.

[0422] The single-sided coating weight of the positive electrode film is 300mg / 1540.25mm 2 .

[0423] 2. Preparation of negative electrode sheet

[0424] The negative electrode sheet includes a negative electrode tab, a negative electrode current collecting portion and a negative electrode film layer arranged on both sides of the negative electrode current collecting portion. The negative electrode current collecting portion is a copper foil with a thickness of 6 μm.

[0425] The negative electrode film layer is formed by uniformly coating the negative electrode slurry (the solvent is deionized water) on the surface of the negative electrode current collector, drying it, and cold pressing it.

[0426] The single-sided coating weight of the negative electrode film is 130mg / 1540.25mm 2 .

[0427] 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, and the second negative electrode film layer is located on the surface of the first negative electrode film layer.

[0428] The first negative electrode film layer includes a carbon-based material with a mass ratio of 96.5:1:1.5:1, a conductive agent acetylene black, a negative electrode binder styrene-butadiene rubber, and a thickener sodium carboxymethyl cellulose. 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.

[0429] The second negative electrode film layer includes a carbon-based material, a conductive agent acetylene black, a negative electrode binder styrene-butadiene rubber, and a thickener sodium carboxymethyl cellulose in 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.

[0430] 3. Isolation parts

[0431] The separator includes a base film, which is a 7 μm polyethylene film layer with a porosity of 42%.

[0432] 4. Preparation of electrolyte

[0433] The electrolyte includes an organic solvent, lithium salt and additives.

[0434] After mixing the components of the organic solvent, lithium salt and additives are added to prepare an electrolyte.

[0435] The organic solvent includes 10% chain carboxylic acid ester solvent (ethyl acetate) and 75% carbonate solvent (diethyl carbonate, dimethyl carbonate, ethylene carbonate in 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.

[0436] Based on the mass of the electrolyte, the mass content of the additive is 1.5%, which includes vinylene carbonate VC.

[0437] The lithium salt includes 8.5% lithium hexafluorophosphate LiPF6 and 5% lithium bis(fluorosulfonyl)imide.

[0438] The conductivity of the electrolyte at room temperature is 12 mS / cm.

[0439] 5. Preparation of battery cells

[0440] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed between the positive electrode sheet and the negative electrode sheet to serve as an isolation, to obtain a laminated electrode assembly. The electrode assembly is placed in an outer packaging shell, dried, and then injected with electrolyte. After vacuum packaging, standing, forming, shaping, and other processes, a battery cell is obtained. The compaction density of the positive electrode film layer of the battery cell at 0% SOC is 2.5g / cm 3 The compaction density of the negative electrode film at 0% SOC is 1.45g / cm 3 .

[0441] Example 1 uses four electrode terminals, such as Figure 14 As shown, the two positive terminals are respectively located on both sides of the electrode assembly along the length direction, and the two negative terminals are respectively located on both sides of the electrode assembly along the length direction.

[0442] Comparative Example 1 and Comparative Example 2

[0443] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the ratio of the length to the width of the positive electrode film layer was adjusted.

[0444] Comparative Example 3

[0445] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the location and number of the positive electrode tabs were adjusted.

[0446] Example 2-1 and Example 2-2

[0447] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the location and number of the positive electrode tabs were adjusted.

[0448] Example 3-1 and Example 3-2

[0449] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the sizes of the weld stamp area (first area) of the positive electrode tab and the positive electrode adapter were adjusted.

[0450] Example 4

[0451] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the number of electrode terminals was adjusted, and one positive terminal and one negative terminal were used. Figure 20 shown.

[0452] Example 5-1 and Example 5-2

[0453] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the size of the positive electrode film layer was adjusted.

[0454] Performance Testing

[0455] 1. DC internal resistance DCR test of battery cells

[0456] You can refer to the methods in GB / T 31467 "Performance test specification for high-power lithium-ion power batteries for HEV".

[0457] For example, at 25°C, charge the battery cell to 3.65V at a constant current of 0.33C, let it stand for 1 min, then charge it to 3.65V at a constant current of 0.05C, let it stand for 30 min, and discharge it to 2.5V at a constant current of 0.33C. Record the discharge capacity A0 at this time in Ah, and then charge it at a constant current of 0.33C for 0.5A0Ah, and adjust the SOC to 50%.

[0458] After the battery cell is placed at 25℃ for 2 hours, it is discharged at a constant current of 4C for 10 seconds and ∆U is recorded. 放电 , ∆I 放电 , the discharge DCR data of the battery cell is calculated by the following formula, R 放电 =∆U 放电 / ∆I 放电 ,

[0459] Where ∆U 放电 Indicates the voltage change within 10s after the discharge starts, ∆I 放电 Indicates the current value within 10 seconds after the start of discharge.

[0460] 2. Battery cell cycle performance

[0461] At 45°C, charge the battery cell to 3.65V at a constant current of 0.5C, then charge it to 0.05C at a constant voltage, let it stand for 10 minutes, and then discharge it to 2.0V at a constant current of 1C. This is one charge and discharge cycle, and record the first-cycle discharge capacity. Let it stand for 10 minutes and repeat the above charge and discharge cycle until the battery cell discharge capacity decays to 80% of the first-cycle discharge capacity. Stop the test and record the number of cycles.

[0462] The test results are shown in Table 1.

[0463] Table 1

[0464]

[0465] The arrangement of the positive electrode tab and the negative electrode tab in the embodiment and the comparative example can adopt a similar design.

[0466] The number of positive electrode tabs refers to the total number of positive electrode tabs in the same positive electrode sheet.

[0467] The positive electrode tab is protruding on the short side, which means that the positive electrode tab is located on at least one side of the positive electrode current collecting part along the length direction.

[0468] The positive electrode tabs are protruding on one side along the short side, which means that all the positive electrode tabs are located on the same side of the positive electrode current collecting part along the length direction.

[0469] The positive electrode tab is protruding along the long side, which means that the positive electrode tab is located on at least one side of the positive electrode current collecting portion along the width direction.

[0470] The positive electrode tabs are on the same side along the width direction of the positive electrode current collector. Figure 8 As shown in .

[0471] The positive electrode tabs are located on both sides of the long side, which means that multiple positive electrode tabs are located on both sides of the positive electrode current collecting part along the width direction; Figure 10 As shown in .

[0472] n*W1 / W2 refers to the ratio of the length of all positive electrode tabs located on the same side of the positive electrode current collecting portion to the length of the positive electrode current collecting portion.

[0473] s represents the ratio of the size of the first region located at the positive electrode tab along the length direction Z to the size of the positive electrode tab along the length direction, which can be understood as the length ratio of the first region, for example, the length ratio of the weld mark of the positive electrode tab.

[0474] The length of the positive electrode film layer of Comparative Example 1 is relatively small, and the electron transmission path is short, which makes the DCR small, but cannot meet the volume energy density requirements of the battery cell;

[0475] Although the positive electrode film layer of Comparative Example 2 is longer and has a higher volume energy density, the aspect ratio of the positive electrode film layer is too large, and the electron transmission path in the length direction is too long, which makes the internal resistance of the battery cell higher and the heat generation increased, which is not conducive to fast charging and high-temperature cycle performance.

[0476] Compared with Comparative Example 1 and Comparative Example 2, the aspect ratio of the positive electrode film layer of Example 1, Example 5-1 and Example 5-2 of the present application is within an appropriate range, the length of the positive electrode film layer is within an appropriate range, the electron transmission path in the length direction is not too long, the internal resistance can be reduced, the fast charging capability of the battery cell can be improved, and the volume energy density of the battery cell can be improved.

[0477] In Comparative Example 3, the positive electrode tab is arranged on one side of the positive electrode current collecting part along the length direction. The electron transmission path in the length direction is long, the internal resistance of the battery cell is high, and the heat generation is increased, which is not conducive to fast charging and high-temperature cycle performance.

[0478] Compared with Comparative Example 3, the positive electrode tab of the embodiment of the present application is arranged on at least one side of the positive electrode collecting part along the width direction. Electrons are introduced into the positive electrode collecting part through the positive electrode tab and are conducted in the positive electrode collecting part. The transmission path of electrons in the positive electrode collecting part is relatively short, so that the internal resistance on the positive electrode sheet is small and the heat generation is small, which can alleviate the battery side reactions caused by heat accumulation and improve the high-temperature cycle performance and fast charging performance of the battery cell.

[0479] For example, in Example 1, the positive electrode tab can be arranged on one side of the positive electrode current collecting part along the width direction; for example, in Example 2-2, the positive electrode tab can be arranged on both sides of the positive electrode current collecting part along the width direction, both of which can effectively improve the high-temperature cycle performance and fast charging performance of the battery cell.

[0480] When the tab size ratio on the same side is the same (n*W1 / W2 is the same), when the positive tabs are set on both sides, the electron transmission distance can be further shortened and the DCR can be reduced.

[0481] Compared with Example 1, the positive electrode tab size ratio of Example 2-1 is higher, which makes the positive electrode tab have a stronger current capacity and further reduces heat generation, and can more effectively improve the high-temperature cycle performance and fast charging performance of the battery cell.

[0482] Compared with Example 1, Examples 3-1 and 3-2 adjusted the weld area of ​​the positive electrode tab and the positive electrode adapter. As the weld area increases, the current capacity of the positive electrode adapter is further enhanced and the heat generation is further reduced, which can more effectively improve the high-temperature cycle performance and fast charging performance of the battery cell.

[0483] Example 1 uses four electrode terminals, and Example 4 uses two electrode terminals. As the number of electrode terminals increases, the current capacity of the electrode terminals is enhanced and heat generation is reduced, which can more effectively improve the high-temperature cycle performance and fast charging performance of the battery cell.

[0484] Comparative Example 4 and Comparative Example 5

[0485] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the components of the electrolyte were adjusted, wherein:

[0486] In Comparative Examples 4 and 5, the electrolyte includes an organic solvent, which includes a chain carboxylate solvent and a carbonate solvent in a mass ratio of 1:9. The chain carboxylate solvent is ethyl acetate, and the carbonate solvent includes diethyl carbonate, dimethyl carbonate, and ethylene carbonate in a mass ratio of 1:1:1.

[0487] Example 6-1 to Example 6-7

[0488] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the components of the electrolyte were adjusted, wherein:

[0489] In Examples 6-1 to 6-7, the electrolyte includes an organic solvent, which includes a chain carboxylate solvent and a carbonate solvent in a mass ratio of 1:9. The chain carboxylate solvent is ethyl acetate, and the carbonate solvent includes diethyl carbonate, dimethyl carbonate, and ethylene carbonate in a mass ratio of 1:1:1.

[0490] The test results are shown in Table 2.

[0491] Table 2

[0492]

[0493] In Table 2, VC represents vinylene carbonate, and FEC represents fluoroethylene carbonate.

[0494] Adjustment of the electrolyte composition has little effect on the volume energy density of the battery cell.

[0495] In Comparative Example 4, the amount of lithium bis(fluorosulfonyl)imide added is too high. Although it is beneficial to improving the high-temperature cycle performance, it releases a large amount of energy rapidly during thermal runaway, which may deteriorate the reliability of use. Moreover, if the amount of lithium bis(fluorosulfonyl)imide added is too high, the SEI film on the negative electrode side may be excessively formed, increasing the impedance, which is not conducive to fast charging.

[0496] In Comparative Example 5, no lithium bis(fluorosulfonyl)imide additive was added, and a large amount of lithium hexafluorophosphate was added to the electrolyte. The excess hexafluorophosphate decomposed to generate a large amount of hydrofluoric acid HF, which damaged the SEI film. The SEI film was repeatedly repaired, and the side reaction on the negative electrode was aggravated, deteriorating the cycle and DCR.

[0497] In the embodiment of the present application, the mass content of lithium bis(fluorosulfonyl)imide in the electrolyte is 1% to 15%, so that the HF content in the electrolyte will not be too high, the SEI film formed on the negative electrode side is stable, and can play an excellent protective role on the negative electrode active material, alleviate the side reaction on the negative electrode side, and improve the high-temperature cycle performance; and the electrolyte has a strong ion conductivity, and the impedance of the SEI film is relatively low, which can reduce the internal resistance of the electrochemical system and is conducive to improving the fast charging capability; and because

[0498] Furthermore, when the mass ratio of lithium hexafluorophosphate to lithium bis(fluorosulfonyl)imide is within an appropriate range, the internal resistance of the battery cell can be further effectively improved, thereby improving the fast charging capability and cycle performance of the battery cell.

[0499] Both additives VC and FEC can form a dense and uniform film layer on the negative electrode side, which can effectively repair the SEI film and provide excellent protection for the negative electrode active materials, which is beneficial to improving the fast charging performance of the battery cell and improving the cycle performance.

[0500] Example 7

[0501] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the arrangement of the negative electrode film layer was adjusted. Specifically:

[0502] 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 conductive layer, and the second negative electrode film layer is located on the surface of the first negative electrode film layer.

[0503] The first negative electrode film layer includes a carbon-based material, a conductive agent acetylene black, a negative electrode binder styrene-butadiene rubber, and a thickener sodium carboxymethyl cellulose in a mass ratio of 96.5:1:1.5:1. The carbon-based material of the first negative electrode film layer includes artificial graphite, and the volume average particle size of the carbon-based material is 8.0 μm.

[0504] The second negative electrode film layer includes a carbon-based material with a mass ratio of 96.5:1:1.5:1, a conductive agent acetylene black, a negative electrode binder styrene-butadiene rubber, and a thickener sodium carboxymethyl cellulose. The carbon-based material of the second 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.

[0505] The test results are shown in Table 3.

[0506] Table 3

[0507]

[0508] The embodiments of the present application are applicable to single-layer negative electrode film layers and double-layer negative electrode film layers. The volume average particle size of the carbon-based material of the first negative electrode film layer is smaller than the volume average particle size of the carbon-based material of the second negative electrode film layer, which can also improve the fast charging performance and cycle performance of the battery cell.

[0509] Although 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 embodiments of the present application, and that changes, substitutions, and modifications may be made to the embodiments without departing from the spirit, principles, and scope of the embodiments of the present application.

Claims

1. A battery cell, characterized in that: The battery cell includes an electrode assembly and an electrolyte, The electrode assembly includes 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 sheet and the second pole sheet includes 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 along the width direction of the battery cell. 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 coated portion of the positive electrode sheet along the length direction of the battery cell is a first size, the size of the coated portion of the positive electrode sheet along the width direction is a second size, and the ratio of the first size to the second size is 4 to 7; The electrolyte comprises lithium bis(fluorosulfonyl)imide, wherein the mass content of the lithium bis(fluorosulfonyl)imide in the electrolyte is 1% to 15%; The first pole piece satisfies: n*W1 / W2 is 0.5 to 1.0; n represents the number of all the tabs located on the same side of the coating portion; W1 represents the average size of the pole ear portion along the length direction; W2 represents the dimension of the coating portion along the length direction.

2. The battery cell according to claim 1, wherein: The electrolyte further includes lithium hexafluorophosphate. Based on the mass of the electrolyte, the ratio of the mass content of the lithium hexafluorophosphate to the mass content of the lithium bis(fluorosulfonyl)imide is 0.5 to 4.

3. The battery cell according to claim 2, characterized in that: Based on the mass of the electrolyte, the ratio of the mass content of the lithium hexafluorophosphate to the mass content of the lithium bis(fluorosulfonyl)imide is 1.2 to 2.

4. The battery cell according to claim 1, wherein: The mass content of the lithium bis(fluorosulfonyl)imide in the electrolyte is 3% to 12%.

5. The battery cell according to claim 1, characterized in that The conductivity of the electrolyte at room temperature is 10 mS / cm to 13 mS / cm.

6. The battery cell according to claim 1, characterized in that The electrolyte also includes a chain carboxylate solvent.

7. The battery cell according to claim 6, characterized in that The mass content of the chain carboxylate solvent in the electrolyte is 5% to 30%.

8. The battery cell according to claim 7, characterized in that W2 is 300 mm to 650 mm; and / or n*W1 is 150 mm to 650 mm.

9. The battery cell according to claim 1, characterized in that The first pole piece includes a plurality of pole lugs.

10. The battery cell according to claim 9, characterized in that: There are at least two pole lugs located on the same side of the coating portion in the first pole piece, and a distance between two adjacent pole lugs along the length direction is greater than 0 and less than or equal to 300 mm.

11. The battery cell according to claim 9 or 10, characterized in that: The plurality of pole lug portions of the first pole piece are located on both sides of the coating portion along the width direction.

12. The battery cell according to claim 9 or 10, characterized in that: All the pole lug portions of the first pole piece are located on the same side of the coating portion along the width direction.

13. The battery cell according to claim 1, characterized in that The dimension of the coating portion of the first pole piece along the width direction is greater than 0 and less than or equal to 300 mm.

14. The battery cell according to claim 1, characterized in that The battery cell further includes a first electrode terminal, the first electrode terminal is connected to the pole ear portion of the first pole piece, and the first electrode terminal is arranged on at least one side of the electrode assembly along the length direction; and / or The battery cell further includes a second electrode terminal connected to the pole ear portion of the second pole piece, and the second electrode terminal is disposed on at least one side of the electrode assembly along the length direction.

15. The battery cell according to claim 14, characterized in that All the pole lugs of the first pole piece are located on the same side of the coating portion, all the pole lugs of the second pole piece are located on the same side of the coating portion, and the pole lugs of the first pole piece and the pole lugs of the second pole piece are respectively located on both sides of the coating portion along the width direction; There is one first electrode terminal and one second electrode terminal, and the first electrode terminal and the second electrode terminal are respectively located on both sides of the electrode assembly along the length direction. The first electrode terminal and the second electrode terminal are staggered along the width direction, and the first electrode terminal is arranged close to the pole ear portion of the first pole piece, and the second electrode terminal is arranged close to the pole ear portion of the second pole piece.

16. The battery cell according to claim 14, characterized in that There are two first electrode terminals, and the two first electrode terminals are respectively arranged on both sides of the electrode assembly along the length direction; and / or There are two second electrode terminals, and the two second electrode terminals are respectively arranged on both sides of the electrode assembly along the length direction.

17. The battery cell according to claim 14, characterized in that The battery cell further includes a first adapter, which is located between the first electrode terminal and the pole ear portion of the first pole piece and connects the first electrode terminal and the pole ear portion of the first pole piece.

18. The battery cell according to claim 17, characterized in that The first adapter includes a first adapter portion and a second adapter portion. The first adapter portion extends along the length direction and connects to the electrode ear portion. The second adapter portion is connected to the first adapter portion and protrudes from the first adapter portion along the width direction and is connected to the first electrode terminal.

19. The battery cell according to claim 17 or 18, characterized in that: The pole lug portion includes a first region connected to the first adapter, and a ratio of a dimension of the first region along the length direction to a dimension of the pole lug portion along the length direction is 0.5 to 1.

20. The battery cell according to claim 1, characterized in that The pole ear portion is provided on at least one side of the coating portion along the width direction of the battery cell, and the pole ear portion extends along the length direction and has a gap between the pole ear portion and the coating portion; The battery cell further includes a heat conduction member disposed at least in the gap.

21. The battery cell according to claim 20, characterized in that The battery cell further includes a case that accommodates the electrode assembly and the electrolyte, wherein the heat conduction member extends to the case and contacts the case.

22. The battery cell according to claim 1, characterized in that The thickness of the battery cell is 10 mm to 30 mm.

23. The battery cell according to claim 1, characterized in that The battery cell further includes a housing, the housing including: two first shell portions facing each other along the thickness direction; and The second shell portion and the third shell portion are opposite to each other, the second shell portion and the third shell portion are connected through the first shell portion, the second shell portion includes a first wall and a second wall continuously arranged along the thickness direction, and the first wall and the second wall are welded.

24. The battery cell according to claim 23, characterized in that The thickness of the shell is 0.1 mm to 0.5 mm.

25. The battery cell according to claim 1, characterized in that The olivine-structured lithium-containing phosphate includes lithium iron phosphate.

26. The battery cell according to claim 25, characterized in that The positive electrode sheet includes a positive electrode film layer, and the single-side coating weight of the positive electrode film layer is 250 mg / 1540.25 mm 2 Up to 330mg / 1540.25mm 2 and / or The battery cell is at 0% state of charge, and the compaction density of the positive electrode film layer is 2.30 g / cm 3 to 2.70g / cm 3 .

27. The battery cell according to claim 1, characterized in that The coating portion of the negative electrode sheet includes a negative electrode current collecting portion and a negative electrode film layer provided on at least one side of the negative electrode current collecting portion, wherein the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material, wherein the negative electrode film layer includes: A first negative electrode film layer is provided 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.

28. The battery cell according to claim 27, characterized in that The carbon-based material of the first negative electrode film layer is in a granular form, 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.

29. The battery cell according to claim 27 or 28, 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.

30. The battery cell according to claim 1, characterized in that The coating portion of the negative electrode sheet includes a negative electrode current collecting portion and a negative electrode film layer provided on at least one side of the negative electrode current collecting portion, wherein the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material, wherein the negative electrode film layer includes: A first negative electrode film layer is provided 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 smaller than the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer.

31. The battery cell according to claim 30, characterized in that The carbon-based material of the second negative electrode film layer is in a granular form, and its volume average particle size Dv50 is 9.5 μm to 18.5 μm; and / or The carbon-based material of the first negative electrode film layer is in a granular form, and its volume average particle size Dv50 is 7.8 μm to 14.3 μm.

32. The battery cell according to claim 30 or 31, characterized in that: 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.

33. The battery cell according to claim 27, characterized in that The single-sided coating weight of the negative electrode film layer is 120 mg / 1540.25 mm 2 Up to 180mg / 1540.25mm 2 and / or The battery cell is at 0% state of charge, and the compaction density of the negative electrode film layer is 1.30 g / cm 3 Up to 1.65g / cm 3 .

34. A battery device, characterized in that: The battery device includes the battery cell according to any one of claims 1 to 33.

35. An electrical device, characterized in that: The electrical device comprises the battery device as claimed in claim 34.

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