Battery cell, battery device, and electric device

Abstract

The application provides a battery monomer, a battery device and a power consumption equipment. The battery monomer comprises: a shell comprising a shell body, a positive electrode end cover assembly and a negative electrode end cover assembly, the shell body has two openings oppositely arranged along a first direction, the first direction is the extension direction of the longest side of the battery monomer, and the positive electrode end cover assembly and the negative electrode end cover assembly are respectively arranged on the openings; an electrode assembly comprising an electrode tab, the electrode tab comprising a positive electrode tab, the positive electrode tab comprising a positive electrode film layer; the positive electrode tab comprising a positive electrode main body part and a positive electrode tab, the positive electrode tab extending from the positive electrode main body part along the first direction; an insulating support arranged between the positive electrode end cover assembly and the positive electrode tab, the insulating support comprising a through hole, the positive electrode tab passing through the through hole and being connected with the positive electrode end cover assembly; the positive electrode main body part comprising a first transition zone, along the first direction, the first transition zone being located at one end of the positive electrode film layer close to the positive electrode tab, the first transition zone comprising an insulating material, and the size of the first transition zone being 0 mm to 2 mm.

Description

[0001] Cross-reference to related applications

[0002] This patent document claims priority and benefit to PCT patent application No. PCT / CN2025 / 137446, filed on November 25, 2025, entitled "Battery Cell, Battery Device and Electrical Equipment". The entire contents of the aforementioned patent application are incorporated herein by reference as a part of the disclosure of this patent document. Technical Field

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

[0004] In recent years, secondary batteries, primarily lithium-ion batteries, have been widely used in energy storage systems for hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and many other fields, resulting in significant development. With the advancement of battery applications, higher demands are being placed on the performance of individual battery cells, such as higher energy density and improved safety performance. Summary of the Invention

[0005] This application provides a battery cell, a battery device, and an electrical appliance, wherein the battery cell has good energy density, rate performance, and safety performance.

[0006] In a first aspect, a battery cell is provided, including a housing, a positive terminal cover assembly, and a negative terminal cover assembly. The housing has two openings disposed opposite each other along a first direction, the first direction being the extension direction of the longest side of the battery cell. The positive terminal cover assembly and the negative terminal cover assembly respectively cover the openings. An electrode assembly includes a plurality of stacked electrode plates. The electrode assembly includes a tab portion and a main body portion, the tab portion extending from the main body portion along the first direction. The electrode plates include a positive electrode plate, the positive electrode plate including a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. The membrane layer includes a positive electrode active material; the positive electrode sheet includes a positive electrode body and a positive electrode tab, the positive electrode tab extending from the positive electrode body along the first direction; an insulating support is provided between the positive electrode cap assembly and the positive electrode tab, the insulating support includes a through hole, the positive electrode tab passing through the through hole to connect with the positive electrode cap assembly; the positive electrode body includes the positive electrode membrane layer and a first transition region, along the first direction, the first transition region is located at one end of the positive electrode membrane layer near the positive electrode tab, the first transition region includes an insulating material, and along the first direction, the size of the first transition region is 0 mm to 2 mm.

[0007] In the battery cell of this application, the casing has openings on both sides in a first direction, and the electrode assembly is disposed within the casing. The electrode assembly has a stacked structure, thus the battery cell has a high energy density. In this high-energy-density battery cell, a first transition region is provided on the side of the positive electrode body near the positive electrode tab of the positive electrode sheet. This first transition region reduces burrs generated during the cutting of the positive electrode sheet and reduces the risk of the positive electrode tab being inserted backwards into the body during battery cell assembly, causing a short circuit between the positive and negative electrodes, thereby improving the safety performance of the battery cell. However, the provision of the first transition region reduces the load of the positive electrode active material on the positive electrode sheet to some extent. Therefore, this application provides an insulating support on the positive side to gather and fix the positive electrode tab, effectively preventing the positive electrode tab from being inserted backwards into the body. Thus, the dimension of the first transition region in the first direction can be 0 mm, thereby further increasing the energy density of the battery cell. In summary, the solution of this application can improve the energy density of the battery cell while improving its safety performance.

[0008] In one possible implementation, the insulating support has a perforated structure that allows electrolyte to pass through it. This arrangement facilitates electrolyte wetting of the electrode assembly, thereby improving the rate performance of the battery cells.

[0009] In one possible implementation, along the first direction, the ratio of the size of the first transition region to the size of the positive electrode body is 0.4% to 1.3%. This arrangement helps to balance energy density and safety performance in the battery cell.

[0010] In one possible implementation, the positive electrode tab includes a second transition region along the first direction, located at one end of the positive electrode tab near the positive electrode body, and the second transition region is provided with insulating material. This arrangement helps to further improve the safety performance of the battery cell.

[0011] In one possible implementation, the size of the second transition region along the first direction is 3 mm to 6 mm. This arrangement helps to balance energy density and safety performance in a single battery cell.

[0012] In one possible implementation, along the first direction, the ratio of the size of the second transition region to the size of the positive electrode tab is 1 / 8 to 1 / 3. This arrangement helps improve the safety performance of high-energy-density battery cells while reducing their assembly difficulty.

[0013] In one possible implementation, the electrode sheet includes a negative electrode sheet, which includes a negative current collector and a negative electrode film layer disposed on at least one side surface of the negative current collector. The negative electrode film layer includes a negative electrode active material; along the first direction, the edge of the negative electrode film layer extends beyond the edge of the positive electrode film layer. This arrangement helps to improve lithium plating during battery cell cycling and further enhances the safety performance of the battery cell.

[0014] In one possible implementation, when the size of the first transition region is 0 mm, the positive electrode body includes an empty foil region located at one end of the positive electrode film layer near the positive electrode tab along the first direction.

[0015] In one possible implementation, the insulating material includes at least one of alumina, boehmite, magnesium oxide, polyacrylate, and polyvinylidene fluoride. This arrangement helps improve the insulation of the first transition region, thereby enhancing the safety performance of the battery cell.

[0016] In one possible implementation, the insulating material includes an adhesive, which comprises at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene copolymer, PVDF-hexafluoropropylene copolymer, PVDF-trifluoroethylene copolymer, and PVDF-chlorotrifluoroethylene copolymer. This arrangement helps improve the insulation and structural stability of the first transition region, thereby enhancing the safety performance of the battery cell.

[0017] In one possible implementation, the positive electrode sheet has a dimension of 225 mm to 240 mm along the first direction; the positive electrode sheet has a dimension of 80 mm to 120 mm along the second direction; the second direction is the height direction of the battery cell, and the second direction is perpendicular to the first direction. This arrangement helps to enable the battery cell to achieve both energy density and rate performance.

[0018] In one possible implementation, the negative electrode sheet has a dimension of 227 mm to 245 mm along the first direction; and a dimension of 80 mm to 120 mm along the second direction. This arrangement helps to balance energy density and rate performance in the battery cell.

[0019] In one possible implementation, the insulating support includes two opposing bosses connected by two beams; the two bosses and the two beams enclose the through hole. This arrangement facilitates the positive electrode tab to pass through the insulating support and provides space for bending the positive electrode tab between the electrode assembly body and the positive end cap assembly, allowing at least a portion of the positive electrode tab to be accommodated in the receiving cavity of the insulating support. This reduces the risk of the positive electrode tab being inserted upside down into the electrode assembly body during assembly, while also saving space occupied by the positive electrode tab in the first direction, allowing the battery cell to balance energy density and safety performance.

[0020] In one possible implementation, the boss is larger than the beam in the thickness direction of the insulating support. This arrangement helps to achieve both high energy density and safety performance in the battery cell.

[0021] In one possible implementation, along the first direction, the boss has a size of 5.0 mm to 9.0 mm; the beam has a size of 3.0 mm to 9.0 mm. This arrangement helps to achieve both high energy density and safety performance in the battery cell.

[0022] In one possible implementation, the boss is provided with a channel structure for allowing electrolyte to pass through the insulating support. This arrangement is more conducive to electrolyte wetting of the electrode assembly, which is beneficial to the rate performance of the battery cells.

[0023] In one possible implementation, the ratio of the maximum dimension of the positive electrode tab along the second direction to the dimension of the positive electrode sheet along the second direction is 1 / 4 to 1 / 2. This arrangement helps to improve the overcurrent capacity of the positive electrode tab, enabling the battery cell to balance safety performance and energy density.

[0024] In one possible implementation, the positive terminal cover assembly includes a first cover body with at least one tab outlet hole for the positive terminal tab to pass through and be electrically connected to the first cover body. This arrangement enhances the reliability of the connection between the positive terminal tab and the overall end cover assembly, and allows the positive terminal cover assembly to accommodate at least part of the positive terminal tab, further saving space occupied by the positive terminal tab in the first direction and helping to improve the safety performance and energy density of the battery cell.

[0025] In one possible implementation, the battery cell includes a metal sheet, and the positive electrode tab is welded to the metal sheet. The metal sheet is used to pass through a lead-out hole of the tab and is welded to the first cover to electrically connect the positive electrode tab to the first cover. This arrangement helps reduce the welding difficulty between the positive electrode tab and the first cover, reduces the probability of deformation of the positive electrode tab when passing through the through hole, further reduces the risk of reverse insertion of the positive electrode tab, and helps improve the safety performance of the battery cell.

[0026] In one possible implementation, the thickness of the metal sheet is 0.15 mm to 0.4 mm. This arrangement allows the positive electrode of the battery cell to have sufficient current carrying capacity while reducing the impact of mechanical components on the energy density of the battery cell.

[0027] In one possible implementation, the first cover includes a first positive electrode outlet hole and a second positive electrode outlet hole arranged parallel to a third direction, the third direction being the width direction of the battery cell, and perpendicular to both the first and second directions; a plurality of positive electrode plates of the electrode assembly are stacked along the third direction; the electrode assembly includes a first electrode assembly and a second electrode assembly, the first electrode assembly including a first positive electrode tab, and the second electrode assembly including a second positive electrode tab; the first positive electrode tab extends through the first positive electrode outlet hole, and the second positive electrode tab extends through the second positive electrode outlet hole. This arrangement helps to reduce the tab space of the positive electrode plates, improve the space utilization rate inside the battery cell casing, and further improve the energy density of the battery cell.

[0028] In one possible implementation, the first cover has a first flat portion and a first recessed portion recessed into the battery cell along the first direction. The first recessed portion is configured to accommodate at least a portion of the positive electrode tab or the metal sheet passing through the tab outlet hole. This arrangement helps to further save the space occupied by the positive electrode tab in the first direction and improve the energy density of the battery cell.

[0029] In one possible implementation, the first recess has a first surface and a second surface along the first direction, the first surface being the surface facing away from the electrode assembly, and the second surface being the surface facing the electrode assembly; at least a portion of the positive electrode tab is welded to the first surface, or at least a portion of the metal sheet is welded to the first surface. This arrangement helps to further save the space occupied by the positive electrode tab in the first direction and improve the energy density of the battery cell.

[0030] In one possible implementation, the casing is positively charged. This arrangement helps mitigate the corrosion of the battery cell casing by the electrolyte, further improving the safety performance of the battery cell.

[0031] In one possible implementation, the first straight portion has a third surface and a fourth surface along the first direction, the third surface being located inside the battery cell and the fourth surface being located outside the battery cell; the distance between the main body portion and the third surface along the first direction is 8.0 mm to 13.0 mm. This arrangement helps to balance energy density and safety performance in the battery cell.

[0032] In one possible implementation, the positive terminal cap assembly includes a second cap body welded to the first cap body. The second cap body has a second flat portion and a first protrusion projecting outward from the battery cell along the first direction. The first protrusion is disposed opposite to the third surface and configured to accommodate at least a portion of the positive electrode tab or the metal sheet passing through the tab lead-out hole. This arrangement helps to improve the reliability of the battery cell while saving space in the first direction used to accommodate the positive electrode tab, allowing the battery cell to balance safety performance and energy density.

[0033] In one possible implementation, the first cover further has a second recess recessed into the battery cell along the first direction, the second recess accommodating the second straight portion, so that the first cover and the second cover can be welded together. This arrangement is more conducive to the welding of the positive terminal cover assembly, thereby improving the reliability and current carrying capacity of the positive terminal cover assembly.

[0034] In one possible implementation, the negative terminal cap assembly includes a negative terminal, which includes a negative terminal post; the negative electrode plate includes a negative electrode tab, which extends from the negative electrode plate along the first direction and is welded to the negative terminal post; alternatively, the negative electrode tab extends from the negative electrode plate along the first direction and is welded to the negative terminal post via a busbar component. This arrangement helps reduce the welding difficulty between the negative electrode tab and the negative terminal cap assembly, and improves the current carrying capacity of the negative electrode.

[0035] In one possible implementation, the negative terminal cover assembly includes a third cover body with an electrode lead-out hole through which the negative terminal post passes; the negative terminal cover assembly includes a first insulating member disposed between the negative terminal and the third cover body to insulate the negative terminal from the third cover body. This arrangement helps prevent short circuits between the positive and negative terminals, improving the safety performance of high-energy-density battery cells.

[0036] In one possible implementation, the first insulating member includes a third flat portion and a third recess disposed on one side facing the main body portion; the third recess is configured to accommodate at least a portion of the negative electrode tab. This arrangement helps to save space for the negative electrode tab, further improving the energy density of the battery cell.

[0037] In one possible implementation, the third straight portion has a dimension of 4.5 mm to 8.0 mm along the first direction. This arrangement allows the battery cell to balance safety performance and energy density.

[0038] In one possible implementation, the negative terminal includes a negative electrode post and a limiting portion. The negative electrode post passes through the electrode lead-out hole, and the limiting portion is connected to the negative electrode post. Along the first direction, the limiting portion is located on the side of the third cover facing the electrode assembly, and the limiting portion is configured to prevent the negative electrode post from disengaging from the electrode lead-out hole in a direction away from the electrode assembly. This arrangement helps to increase the current-carrying area between the negative electrode tab and the negative terminal, thereby improving the current-carrying capacity of the negative electrode.

[0039] In one possible implementation, the busbar is a sheet-like structure with a thickness of 0.6 mm to 1.2 mm. This configuration allows the negative electrode to have sufficient current carrying capacity while reducing the impact of mechanical components on the energy density of the battery cells.

[0040] In one possible implementation, a first insulating film is provided between the main body and the housing, the first insulating film serving to insulate the main body from the housing. This arrangement helps prevent short circuits between the positive and negative electrodes, improving the safety performance of the battery cell.

[0041] In one possible implementation, a second insulating film is disposed between the negative electrode tab and the first insulating film. The second insulating film covers the negative electrode tab and extends between the main body and the housing; the second insulating film serves to insulate the negative electrode tab and the housing. This arrangement helps to further prevent short circuits between the positive and negative electrodes, improving the safety performance of the battery cell.

[0042] In one possible implementation, the areal density of the positive electrode sheet on one side is 0.33 g / 1540.25 mm. 2 Up to 0.40g / 1540.25mm 2 This configuration is more conducive to balancing energy density and rate performance in individual battery cells.

[0043] In one possible implementation, when the battery cell is at 0% SOC, the compaction density of the positive electrode sheet is 2.4 g / cm³. 3 Up to 2.7 g / cm 3 This configuration is more conducive to balancing energy density and rate performance in individual battery cells.

[0044] In one possible implementation, the thickness of the positive electrode current collector is 12 μm to 15 μm. This setting is more conducive to the energy density of the battery cell.

[0045] In one possible implementation, the ratio of the thickness of the positive current collector to the total thickness of the positive electrode sheet is 4.5% to 7%.

[0046] In one possible implementation, the areal density of the negative electrode sheet is 0.130 g / 1540.25 mm. 2 Up to 0.175g / 1540.25mm 2 This configuration is more conducive to balancing energy density and rate performance in individual battery cells.

[0047] In one possible implementation, when the battery cell is at 0% SOC, the compaction density of the negative electrode sheet is 1.37 g / cm³. 3 Up to 1.55 g / cm 3 This configuration is more conducive to balancing energy density and rate performance in individual battery cells.

[0048] In one possible implementation, the thickness of the negative electrode current collector is 4 μm to 7 μm. This setting is more conducive to the energy density of the battery cell.

[0049] In one possible implementation, the ratio of the thickness of the negative current collector to the total thickness of the negative electrode sheet is 2% to 6%. This configuration can reduce the thickness ratio of the negative current collector in the negative electrode sheet, allowing more negative active material to be loaded on the negative electrode sheet, increasing the space ratio of the negative electrode film layer within the battery cell casing, thereby further improving the energy density of the battery cell.

[0050] In one possible implementation, a separator is disposed between the electrode plates. The separator includes a base film and a coating disposed on at least one side of the base film, the coating comprising inorganic particles. This arrangement helps improve the insulation of the separator, thereby enhancing the safety performance of the battery cell.

[0051] In one possible implementation, the thickness of the base film is 5 μm to 9 μm. This configuration allows the battery cell to achieve both high energy density and safety performance.

[0052] In one possible implementation, the coating thickness is between 1 μm and 5 μm. This configuration allows the battery cell to achieve both high energy density and safety performance.

[0053] In one possible implementation, the positive electrode active material includes one or more of lithium transition metal oxides and lithium transition metal phosphates.

[0054] In one possible implementation, the battery cell includes an electrolyte comprising a lithium salt, which includes one or more of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate.

[0055] In one possible implementation, the electrolyte comprises lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, wherein the mass fraction of lithium bis(fluorosulfonyl)imide is greater than or equal to the mass fraction of lithium hexafluorophosphate based on the total mass of the electrolyte. This arrangement facilitates a balance between rate performance and safety performance in the battery cell.

[0056] In one possible implementation, the lithium bis(fluorosulfonyl)imide has a mass fraction of 5 wt% to 12 wt% based on the total mass of the electrolyte; alternatively, it can be 8 wt% to 12 wt%. This configuration is more conducive to balancing rate performance and safety performance in the battery cell.

[0057] In one possible implementation, the lithium hexafluorophosphate has a mass fraction of 4.5 wt% to 8 wt% based on the total mass of the electrolyte. This arrangement helps reduce the corrosion of the aluminum foil by the lithium salt, further improving the safety performance of the battery cell.

[0058] In one possible implementation, the lithium salt has a mass fraction of 15 wt% to 20 wt% based on the total mass of the electrolyte. This configuration is beneficial for improving the liquid-phase transport of lithium ions, increasing the ionic conductivity of the electrolyte, and enhancing the rate performance of high-energy-density battery cells.

[0059] In one possible implementation, the electrolyte includes an additive, which comprises one or more of vinylene carbonate and fluoroethylene carbonate. This configuration is beneficial for improving the stability of the solid electrolyte interface (SEI) membrane, reducing the direct current resistance (DCR) of the battery cell, and improving the rate performance of the battery cell.

[0060] In one possible implementation, the mass fraction of vinylene carbonate is from 0.01 wt% to 5.00 wt%, optionally from 1 wt% to 2.5 wt%, based on the total mass of the electrolyte. This configuration is more conducive to enabling the battery cell to achieve both rate performance and cycle performance.

[0061] In one possible implementation, the mass fraction of the fluoroethylene carbonate is from 0.01 wt% to 4 wt%, optionally from 0.1 wt% to 0.5 wt%, based on the total mass of the electrolyte. This configuration is more conducive to balancing rate performance and safety performance in the battery cell.

[0062] In one possible implementation, the electrolyte has an ionic conductivity of 9.0 mS / cm to 13 mS / cm at room temperature. This setting is beneficial for improving the ionic conductivity of the electrolyte and enhancing the rate performance of high-energy-density battery cells.

[0063] In one possible implementation, the electrolyte comprises a cyclic carbonate solvent, including ethylene carbonate. This configuration facilitates the dissociation of lithium salts in the electrolyte, thereby improving the rate performance of high-energy-density battery cells.

[0064] In one possible implementation, the cyclic carbonate solvent has a mass fraction of 15 wt% to 30 wt% based on the total mass of the electrolyte. This arrangement facilitates the dissociation of lithium salts in the electrolyte, enhances the liquid-phase transport of lithium ions, and improves the rate performance of high-energy-density battery cells.

[0065] In one possible implementation, the electrolyte comprises a linear carbonate solvent, including dimethyl carbonate. This configuration helps reduce the viscosity of the electrolyte, improves the liquid-phase transport of lithium ions, and enhances the rate performance of high-energy-density battery cells.

[0066] In one possible implementation, the dimethyl carbonate has a mass fraction of 20 wt% to 35 wt% based on the total mass of the electrolyte. This configuration is more conducive to improving the liquid-phase transport of lithium ions and enhancing the rate performance of high-energy-density battery cells.

[0067] In one possible implementation, the dimension of the battery cell along the first direction is 230 mm to 350 mm, the dimension of the battery cell along the second direction is 100 mm to 130 mm, and the dimension of the battery cell along the third direction is 23 mm to 50 mm. This arrangement is beneficial for improving the energy density of the battery cell.

[0068] In one possible implementation, the main body portion has a dimension of 225 mm to 235 mm along the first direction. This arrangement helps to balance energy density and safety performance in the battery cell.

[0069] In one possible implementation, the battery cell includes a pressure relief mechanism disposed on a first wall of the housing, the first wall having a thickness of 1.2 mm to 1.5 mm. This arrangement helps to improve the safety performance of the battery cell.

[0070] In a second aspect, a battery device is provided, the battery device comprising a battery cell in any possible implementation of the first aspect.

[0071] Thirdly, an electrical device is provided, the electrical device comprising a battery cell in any possible implementation of the first aspect, or a battery device in the second aspect. Attached Figure Description

[0072] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0073] Figure 1 This is a schematic structural diagram of a single battery cell.

[0074] Figure 2 This is a schematic diagram of an electrode assembly.

[0075] Figure 3 This is a schematic diagram of the main body of an electrode assembly.

[0076] Figure 4 This is a schematic diagram of a positive electrode.

[0077] Figure 5 This is another schematic diagram of a positive electrode.

[0078] Figure 6 This is a schematic structural diagram of a portion of a battery cell.

[0079] Figure 7 This is a schematic diagram of an insulating support component.

[0080] Figure 8 This is a schematic diagram of the main body of another electrode assembly.

[0081] Figure 9 This is a schematic diagram of a negative electrode.

[0082] Figure 10 This is a schematic top view of the first cover.

[0083] Figure 11 This is another partial schematic diagram of a battery cell.

[0084] Figure 12 This is another partial schematic diagram of a single battery cell.

[0085] Figure 13 This is a schematic diagram of a second insulating film.

[0086] Figure 14 A schematic diagram of a battery device.

[0087] Figure 15 This is a schematic diagram of an electrical device. Detailed Implementation

[0088] The embodiments of this application are hereby disclosed 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 repetitive descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0089] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0090] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicating orientation or positional relationships are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0091] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) 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 it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0092] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0093] Unless otherwise specified, any undefined terms shall have their technically accepted meanings.

[0094] To further improve the energy density of a single battery cell, a feasible approach is to employ an electrode assembly with a stacked structure and place the positive and negative electrode tabs on both sides of the electrode assembly along the length of the casing. This design can improve the space utilization within the battery cell casing, thereby increasing the energy density of the battery cell. However, during the preparation of the positive electrode sheet in the aforementioned high-energy-density battery cell, for example, during the preparation of the positive electrode tab by cutting, or during the cutting of a large positive electrode sheet into multiple positive electrode sheets, burrs are usually generated at the cutting point, resulting in burrs on the edges of the cut positive electrode sheets. These burrs can easily puncture the separator, leading to a short circuit between the positive and negative electrodes. Simultaneously, during the assembly process of the aforementioned high-energy-density battery cell, with the positive and negative electrode tabs placed on both sides of the electrode assembly, it is necessary to pass the electrode assembly without welded positive electrode tabs through the casing and lead out the positive electrode tabs during assembly. Therefore, if the length of the positive electrode tabs is insufficient, it will not meet the assembly requirements. Thus, in a battery cell with the aforementioned structural configuration, the length of the positive electrode tabs cannot be too short. This increases the probability that the positive electrode tab will be inserted backwards into the electrode assembly during assembly, raising the risk of short circuit between the positive and negative electrodes of the battery cell and affecting the safety performance of the battery cell.

[0095] To address the aforementioned issues, this application improves the structure and materials of the battery cell, enabling the high-energy-density battery cell to balance high energy density and safety performance. Specifically:

[0096] The electrode assembly has a stacked structure, and the positive and negative electrode tabs are located on both sides of the electrode assembly along the length of the casing. Therefore, the battery cell has a high energy density.

[0097] The positive electrode sheet has a first transition region including an insulating material on the side near the positive electrode tab. The first transition region can reduce the burrs generated during the cutting process of the positive electrode sheet and block the burrs, reducing the probability of the burrs piercing the separator and causing a short circuit between the positive and negative electrodes. On the other hand, it can reduce the risk of the positive electrode tab being inserted into the main body and causing a short circuit between the positive and negative electrodes. Thus, it can effectively improve the safety performance of high energy density battery cells.

[0098] However, the presence of the first transition zone reduces the load of the positive electrode active material on the positive electrode sheet to some extent. Therefore, this application, by providing an insulating support on the positive electrode side to gather and fix the positive electrode tab, can effectively prevent the positive electrode tab from being inserted backwards into the main body. This allows the dimension of the first transition zone in the first direction to be 0 mm, thus enabling the battery cell to balance high energy density and safety performance. Furthermore, when the dimension of the first transition zone is not 0 mm, the safety performance of the high-energy-density battery cell can be further improved.

[0099] In summary, the solution proposed in this application can improve the energy density of a single battery cell while simultaneously enhancing its safety performance.

[0100] The embodiments of this application will be described next.

[0101] [Battery cell]

[0102] First, this application provides a single battery cell.

[0103] Figure 1 This is a schematic structural diagram of a battery cell according to this application. Figure 2 This is a schematic diagram of an electrode assembly according to this application. Figure 3 This is a schematic diagram of the main body of an electrode assembly according to this application. Figure 4 This is a schematic diagram of a positive electrode sheet according to this application. Figure 5 This is another schematic diagram of a positive electrode sheet according to this application. Figure 6 This is a partial schematic diagram of a battery cell according to this application. Figure 7 This is a schematic diagram of an insulating support member according to this application.

[0104] like Figure 1-4 As shown, the battery cell 10 includes a housing, which includes a casing 121, a positive terminal cover assembly 122a, and a negative terminal cover assembly 122b. The casing 121 has two openings that are arranged opposite to each other along a first direction X. The positive terminal cover assembly 122a and the negative terminal cover assembly 122b respectively cover the openings. The first direction X is the extension direction of the longest side of the battery cell 10.

[0105] like Figure 1 and Figure 2As shown, the electrode assembly 11 includes a plurality of stacked electrode plates. The electrode assembly 11 includes a main body and an electrode tab 112, which extends from the main body along a first direction X.

[0106] like Figure 3 and Figure 5 As shown, the electrode includes a positive electrode 13, which includes a positive current collector 131 and a positive electrode film 132 disposed on at least one side surface of the positive current collector 131. The positive electrode film 132 includes a positive active material. The positive electrode 13 includes a positive electrode body portion 134 and a positive electrode tab 133, which extends from the positive electrode body portion 134 along a first direction X.

[0107] like Figure 1 , Figure 6 and Figure 7 As shown, an insulating support 1223 is provided between the positive terminal cap assembly 122a and the positive terminal tab 133. The insulating support 1223 includes a through hole 301, through which the positive terminal tab 133 passes and is connected to the positive terminal cap assembly.

[0108] like Figure 5 As shown, the positive electrode body 134 includes a positive electrode film layer 132 and a first transition region 1341. Along the first direction X, the first transition region 1341 is located at one end of the positive electrode film layer 132 near the positive electrode tab 133, and the first transition region 1341 includes an insulating material. Along the first direction X, the size of the first transition region 1341 is 0 mm to 2 mm. The dimensions of the first transition region 1341 in the first direction X are as follows... Figure 5 As shown in L7.

[0109] Typically, an electrode assembly includes a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrodes. Electrode assemblies with a stacked structure are usually made by alternately stacking the positive and negative electrodes in sequence, separated by a separator arranged in a Z-shape, thus obtaining an electrode assembly with a stacked structure.

[0110] Figure 8 This is a schematic diagram of the main body of another electrode assembly.

[0111] In some embodiments, such as Figure 8As shown, the electrode assembly body 111 includes a positive electrode 13 and a negative electrode 14. The negative electrode 14 may include at least one bent section and multiple stacked sections. Each bent section is used to connect two stacked sections. The multiple positive electrode 13s and the multiple stacked sections of the negative electrode 14 are alternately stacked along the electrode thickness direction to form another form of electrode assembly 11 with a stacked structure. Alternatively, the electrode assembly body 111 of the electrode assembly 11 with a stacked structure includes multiple negative electrode 14s and positive electrode 13s. The positive electrode 13 includes at least one bent section and multiple stacked sections. Each bent section is used to connect two stacked sections. The multiple negative electrode 14s and the multiple stacked sections of the positive electrode 13 are alternately stacked along the electrode thickness direction.

[0112] This shows that electrode assemblies with a stacked structure have no bending areas and, when placed in the casing of a battery cell, have a higher space utilization rate than electrode assemblies with a wound structure, thus having a higher energy density.

[0113] In this application, the electrode assembly has a stacked structure, and the tabs extend from the main body along a first direction, which makes the internal space utilization of the battery cell casing high, thereby giving the battery cell a high energy density.

[0114] In the preparation process of the positive electrode sheet in the aforementioned high-energy-density battery cell, for example, during the preparation of the positive electrode tab by cutting, or during the cutting of a large positive electrode sheet into multiple positive electrode sheets, burrs are usually generated at the cutting point, resulting in burrs on the edges of the cut positive electrode sheets. These burrs can easily puncture the separator during the cycling and storage of the battery cell, leading to a short circuit between the positive and negative electrodes and affecting the safety performance of the battery cell.

[0115] In the assembly process of the aforementioned high-energy-density battery cells, the positive and negative electrode tabs are located on both sides of the electrode assembly. Therefore, during the assembly of the battery cell, it is necessary to pass the electrode assembly without the positive electrode tab welded to it through the casing and bring out the positive electrode tab. Consequently, if the length of the positive electrode tab is insufficient, the assembly requirements cannot be met. Therefore, in battery cells with the above structural configuration, the length of the positive electrode tab cannot be too short. This increases the probability of the positive electrode tab being inserted backwards into the electrode assembly during assembly, raising the risk of a short circuit between the positive and negative electrodes in the battery cell and affecting its safety performance.

[0116] Therefore, in this application, by providing a first transition region including insulating material on the side of the positive electrode sheet near the positive electrode tab in the aforementioned high-energy-density battery cell, it is possible to reduce burrs generated during the cutting process of the positive electrode sheet and to block the burrs, thereby reducing the probability of burrs piercing the separator and causing a short circuit between the positive and negative electrodes. Furthermore, it reduces the risk of the positive electrode tab being inserted backwards into the main body, leading to a short circuit between the positive and negative electrodes. Thus, the safety performance of the high-energy-density battery cell can be effectively improved. However, the provision of the first transition region reduces the load of the positive active material on the positive electrode sheet to some extent. Therefore, this application provides an insulating support on the positive side to gather and fix the positive electrode tab, effectively preventing the positive electrode tab from being inserted backwards into the main body. This allows the size of the first transition region in the first direction to be 0 mm, thus enabling the battery cell to balance high energy density and safety performance. Furthermore, when the size of the first transition region is not 0 mm, the safety performance of the high-energy-density battery cell is further improved.

[0117] In summary, the solution proposed in this application can improve the energy density of a single battery cell while simultaneously enhancing its safety performance.

[0118] For example, the size L7 of the first transition zone in the first direction is 0 mm to 2 mm, for example, 0 mm, 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, or a value within the range obtained by any combination of the above two values.

[0119] When the dimension of the first transition region in the first direction is 0 mm, it can be either an area where the original insulating material was provided that is an empty foil area, or at least a portion of the area where the original insulating material was provided that is provided with a positive electrode film layer.

[0120] In one embodiment, when the size of the first transition region is 0 mm, the positive electrode body includes an empty foil region located at one end of the positive electrode film layer near the positive electrode tab along a first direction.

[0121] If the size of the first transition region is not 0 mm in the first direction, and the size of the first transition region is too large, it will occupy the space originally set for the positive electrode film layer, resulting in a loss of positive electrode active material and negatively impacting the energy density of the battery cell. If the size of the first transition region is too small, it cannot effectively block burrs and prevent the positive electrode tab from causing a short circuit between the positive and negative electrodes, which is detrimental to the safety performance of the battery cell. Therefore, this application controls the size of the first transition region to be less than or equal to 2 mm, which is more conducive to achieving both energy density and safety performance in the battery cell.

[0122] The dimensions of the first transition region in the first direction, as well as other dimensions of the electrode, can be measured using methods known to those skilled in the art. In one example, these dimensions can be measured using a ruler after disassembling a battery cell discharged to 0% SOC, with the positive electrode in a flat position.

[0123] In this application, a battery cell that is discharged to a cutoff voltage of 2.0V at 0.05C is considered to be a battery cell in a 0% SOC state.

[0124] In a more specific example, the positive electrode film and the first transition region may have an overlapping area, in which insulating material is disposed on the surface of the positive electrode film. In another example, the positive electrode film and the first transition region are connected, meaning there is neither an overlapping area nor a gap between them. In yet another example, a gap may exist between the positive electrode film and the first transition region. In yet another example, there may be both an overlapping area and a gap between the positive electrode film and the first transition region; or there may be both a connecting area and an overlapping area, etc. For example, at one end of the second direction, there is an overlapping area between the positive electrode film and the first transition region, and at the other end of the second direction, there is a gap between them.

[0125] In some embodiments, such as Figure 5 As shown, along the first direction X, the ratio of the size of the first transition region 1341 to the size of the positive electrode body 134 is 0.4% to 1.3%. The size of the positive electrode body 134 along the first direction X is as follows... Figure 5 As shown in L1.

[0126] In the first direction, a larger ratio of the size of the first transition region to the size of the positive electrode body is more beneficial to the safety performance of the battery cell. However, it also leads to a reduction in the loading of positive electrode active material on the positive electrode sheet, affecting the energy density of the battery cell. Therefore, by controlling the ratio of the size of the first transition region to the size of the positive electrode body within the aforementioned range, this application is more conducive to enabling the battery cell to balance energy density and safety performance.

[0127] For example, along the first direction, the ratio of the size of the first transition region to the size of the positive electrode body is 0.4% to 1.3%, for example, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, or a value within the range obtained by any combination of the above two values.

[0128] In some embodiments, please refer to Figure 5The positive electrode tab 133 includes a second transition region 1342 along the first direction X. The second transition region 1342 is located at one end of the positive electrode tab 133 near the positive electrode body portion 134, and the second transition region 1342 is provided with insulating material.

[0129] Burrs may also exist on the edge of the positive electrode tab. These burrs can puncture the separator, causing the positive electrode tab to overlap with the negative electrode, leading to a short circuit and potentially thermal runaway. Therefore, by providing a second transition zone on the side of the positive electrode tab closest to the main body, it is more effective in preventing burrs at the base of the tab from puncturing the separator, further enhancing burr protection and giving the battery cell higher safety performance.

[0130] In some embodiments, such as Figure 5 As shown, along the first direction X, the dimensions of the second transition region 1342 are 3mm to 6mm. The dimensions of the second transition region 1342 along the first direction X are as follows... Figure 5 As shown in L6.

[0131] If the size of the second transition region along the first direction is too large, it will occupy the space available for welding the positive electrode tab, which is detrimental to the assembly and processing of the battery cell; if the size of the second transition region along the first direction is too small, it cannot effectively prevent burrs, which is detrimental to the safety performance of the battery cell. Therefore, this application controls the size of the second transition region to 3mm-6mm, which can improve the energy density and safety performance of the battery cell while reducing the assembly difficulty of the battery cell.

[0132] For example, the size L6 of the second transition zone in the first direction is 3mm-6mm, such as 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, or a value within the range obtained by any combination of the above two values.

[0133] In some embodiments, such as Figure 5 As shown, along the first direction X, the ratio of the size of the second transition region 1342 to the size of the positive electrode tab 133 is 1 / 8 to 1 / 3.

[0134] In the first direction, a larger ratio of the size of the first transition region to the size of the positive electrode body is more beneficial to the safety performance of the battery cell. However, it also leads to a smaller size of the positive electrode tab that can be used for welding, increasing the assembly difficulty of the battery cell and affecting its reliability. Therefore, this application controls the ratio of the size of the second transition region to the size of the positive electrode body in the first direction within the above-mentioned range, which is more conducive to improving the safety performance of high-energy-density battery cells while reducing their assembly difficulty.

[0135] For example, the ratio of the size of the second transition region to the size of the positive electrode tab is 1 / 8 to 1 / 3, such as 1 / 8, 1 / 6, 2 / 9, 1 / 4, 1 / 3, or a value within the range obtained by any combination of the above two values.

[0136] Figure 9 This is a schematic diagram of a negative electrode sheet according to this application.

[0137] In some embodiments, such as Figure 3 , Figure 5 and Figure 9 As shown, the electrode sheet includes a negative electrode sheet 14, which includes a negative current collector 143 and a negative electrode film layer 144 disposed on at least one side surface of the negative current collector 143. The negative electrode film layer 144 includes a negative electrode active material. Along the first direction X, the edge of the negative electrode film layer 144 extends beyond the edge of the positive electrode film layer 132.

[0138] This design allows the edge of the negative electrode film 144, near the positive electrode tab, to fall within the first transition region, effectively preventing short circuits caused by overlap between the positive and negative electrode sheets and helping to improve the safety performance of the battery cell. The area where the edge of the negative electrode film extends beyond the edge of the positive electrode film and the edge of the first transition region can be called the Overhang region. By creating a "redundant" Overhang region with a negative electrode sheet, lithium plating is reduced, further improving the safety performance of the battery cell.

[0139] In some embodiments, the insulating material includes at least one of alumina, boehmite, magnesium oxide, polyacrylate, and polyvinylidene fluoride.

[0140] The aforementioned insulating material is insulating and can block burrs; it helps to improve the insulation of the first transition zone and enable the first transition zone to block burrs, thereby helping to improve the safety performance of the battery cell.

[0141] In some embodiments, the insulating material includes an adhesive, said adhesive including at least one of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, and vinylidene fluoride-trifluorochloroethylene copolymer.

[0142] As an insulating material, the binder possesses insulation, adhesion, and a certain degree of toughness, which can reduce burr formation and insulate the first transition zone, thus helping to improve the safety performance of the battery cell. When the insulating material includes both inorganic particles and a binder, the binder can also adhere the insulating inorganic particles to the surface of the positive electrode current collector, enabling them to better perform their insulating function.

[0143] In some embodiments, such as Figure 5As shown, the positive electrode 13 has a dimension of 225mm to 240mm along the first direction X; the positive electrode 13 has a dimension of 80mm to 120mm along the second direction Y. The second direction Y is the height direction of the battery cell 10, and the second direction Y is perpendicular to the first direction X.

[0144] The positive electrode 13 includes a positive electrode tab 133 and a positive electrode body 134. The dimensions of the positive electrode 13 along the first direction X are as follows: Figure 5 As shown by L1, this refers to the dimension of the positive electrode body 134 in the first direction X. The dimension of the positive electrode sheet 13 along the second direction Y is as follows. Figure 6 As shown in L2, it refers to the dimension of the positive electrode body 134 in the second direction Y.

[0145] For example, the size of the positive electrode sheet along the first direction is 225mm to 240mm, such as 225mm, 226mm, 227mm, 228mm, 229mm, 230mm, 231mm, 232mm, 233mm, 234mm, 235mm, 236mm, 237mm, 238mm, 239mm, 240mm, or a value within the range obtained by any combination of the above two values.

[0146] For example, the size of the positive electrode sheet along the second direction is 80mm to 120mm, such as 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 115mm, 120mm, or a value within the range obtained by any combination of the above two values.

[0147] In some embodiments, such as Figure 9 As shown, the negative electrode 14 has a dimension of 227 mm to 245 mm along the first direction X; the negative electrode 14 has a dimension of 80 mm to 120 mm along the second direction Y.

[0148] The negative electrode 14 includes a negative electrode tab 141 and a negative electrode body 142. The dimensions of the negative electrode 14 along the first direction X are as follows: Figure 9 As shown in L3, this refers to the dimension of the negative electrode body 142 in the first direction X. The dimension of the negative electrode sheet 14 along the second direction Y is as follows. Figure 9 As shown in L4, it refers to the dimension of the negative electrode body 142 in the second direction Y.

[0149] For example, the dimension of the negative electrode sheet along the first direction is 227mm to 245mm, such as 227mm, 228mm, 229mm, 230mm, 231mm, 232mm, 233mm, 234mm, 235mm, 236mm, 237mm, 238mm, 239mm, 240mm, 241mm, 242mm, 243mm, 244mm, 245mm, or a value within the range obtained by any combination of the above two values.

[0150] For example, the dimension of the negative electrode sheet along the second direction is 80mm to 120mm, such as 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 115mm, 120mm, or a value within the range obtained by any combination of the above two values.

[0151] In some embodiments, such as Figure 7 As shown, the insulating support 1223 has a channel structure 302, which allows the electrolyte to pass through the insulating support 1223. This arrangement facilitates the wetting of the electrode assembly by the electrolyte, thereby improving the rate performance of the battery cell.

[0152] In some embodiments, such as Figure 7 As shown, the insulating support 1223 includes two oppositely arranged bosses 31, which are connected by two beams 32; the two bosses 31 and the two beams 32 enclose a through hole 301.

[0153] In some embodiments, such as Figure 6 As shown, the boss 31 is positioned facing the electrode assembly body 111. This provides better space for accommodating the positive electrode tab 133.

[0154] In some embodiments, the boss abuts against at least a portion of the body of the electrode assembly. This saves space occupied by the insulating support in the first direction, helping to increase the energy density of the battery cell.

[0155] In some embodiments, such as Figure 6-7 As shown, in the thickness direction of the insulating support 1223, the size of the boss 31 is larger than the size of the beam 32.

[0156] By making the size of the boss larger than the size of the beam, a space for folding the positive electrode tab can be formed, which reduces the risk of the positive electrode tab being inserted in reverse. At the same time, the insulating support can be made lighter, so that the battery cell can achieve both high energy density and safety performance.

[0157] Preferably, in the thickness direction of the insulating support, the two bosses are of equal size, and the two beams are of equal size.

[0158] In some embodiments, the size of the boss is 5.0 mm to 9.0 mm along the first direction.

[0159] For example, the size of the boss along the first direction is 5.0 mm to 9.0 mm, such as 5.0 mm, 6.0 mm, 7.0 mm, 8.0 mm, 9.0 mm, or a value within the range obtained by any combination of the above two values.

[0160] If the size of the boss is too small along the first direction, it cannot create sufficient space for bending the positive electrode tab, failing to reduce the risk of reverse insertion of the positive electrode tab. Furthermore, it can cause the electrode assembly to wobble within the casing along the first direction, easily pulling on the positive electrode tab and potentially causing it to break, which is detrimental to the safety performance of the battery cell. Conversely, if the size of the boss is too large, the insulating support occupies a significant amount of space along the first direction, which is detrimental to the volumetric energy density of the battery cell. Therefore, controlling the size of the boss along the first direction within the range of 5.0mm to 9.0mm is more conducive to achieving a balance between energy density and safety performance in the battery cell.

[0161] In some embodiments, such as Figure 7 As shown, the boss 31 is provided with a channel structure 302, which allows the electrolyte to pass through the insulating support 1223. This arrangement is more conducive to the wetting of the electrode assembly by the electrolyte, and is beneficial to the rate performance of the battery cell.

[0162] In some embodiments, such as Figure 5 As shown, the ratio of the maximum dimension of the positive electrode tab 133 along the second direction Y to the dimension of the positive electrode plate 13 along the second direction is 1 / 4 to 1 / 2. The maximum dimension of the positive electrode tab 133 along the second direction Y is as follows... Figure 5 As shown in L5, the dimensions of the positive electrode 13 along the second direction are as follows: Figure 5 As shown in L2. The dimension of the positive electrode tab 133 along the second direction Y may fluctuate or have errors due to manufacturing process. Generally speaking, the dimension is largest at the boundary between the positive electrode tab 133 and the positive electrode body 134. Therefore, the maximum dimension of the positive electrode tab 133 along the second direction Y can also be considered as the dimension of the "root" of the positive electrode tab.

[0163] For example, L5 / L2 is 1 / 4 to 1 / 2, such as 1 / 4, 1 / 3, 1 / 2, or its value is within the range obtained by any combination of the two values ​​mentioned above.

[0164] Within the L5 / L2 range, the positive electrode tab is larger in the second direction, meaning it is wider. This is beneficial for improving the current carrying capacity at the positive electrode tab and enhancing the safety performance of the battery cell. However, if the ratio is too large, the positive electrode tab occupies more space inside the casing, which is detrimental to the energy density of the battery cell. Therefore, by controlling the ratio of the tab width to the electrode width within an appropriate range, the battery cell can achieve a balance between energy density and safety performance.

[0165] In some embodiments, such as Figure 6 As shown, the positive terminal cover assembly 122a includes a first cover body 1221, which includes at least one tab lead-out hole 303 for the positive terminal tab 133 to pass through the tab lead-out hole 303 and be electrically connected to the first cover body 1221. In this way, the casing 121 of the battery cell 10 can be positively charged.

[0166] In some embodiments, the casing of the battery cell is positively charged.

[0167] The casing of a battery cell is typically made of aluminum. Aluminum is a reactive metal with a low standard electrode potential, making it prone to electrochemical corrosion in electrolyte environments. In a battery cell, the negative electrode typically has a lower potential. If the aluminum casing comes into contact with the negative electrode, the aluminum casing, being a good conductor, will have a potential close to the negative electrode potential. This causes the aluminum casing to undergo an intercalation reaction with lithium ions in the electrolyte at a low potential, forming an aluminum alloy, which further exacerbates the corrosion of the aluminum casing by the electrolyte.

[0168] Therefore, by electrically connecting the casing of the battery cell to the positive electrode, making it positively charged, the corrosion of the casing by the electrolyte can be effectively reduced, thereby further improving the safety performance of the battery cell.

[0169] Figure 11 This is another partial schematic diagram of a battery cell according to this application.

[0170] In some embodiments, such as Figure 6 and Figure 11 As shown, the battery cell 10 includes a metal sheet 50, and a positive electrode tab 133 is welded to the metal sheet 50. The metal sheet 50 is used to pass through the tab lead-out hole 303 and is welded to the first cover 1221 so that the positive electrode tab 133 is electrically connected to the first cover 1221.

[0171] In this application, by connecting the positive electrode tab to the metal sheet, the positive electrode tab can be pre-welded to the metal sheet. Compared to the scheme where the positive electrode tab is directly connected to the first cover, this reduces the welding difficulty, lowers the risk of cracking of the positive electrode tab during welding, and improves assembly efficiency. Furthermore, during assembly, the thin metal sheet is easier to pass through the lead-out hole, thereby reducing the probability of deformation of the positive electrode tab when passing through the through hole, further reducing the risk of reverse insertion of the positive electrode tab, and helping to improve the safety performance of the battery cell.

[0172] In some embodiments, the thickness of the metal sheet is 0.15 mm to 0.4 mm.

[0173] If the metal sheet is too thin, it hinders current flow at the positive electrode tab, affecting the safety performance of the battery cell; if the metal sheet is too thick, it occupies too much internal space in the battery cell, which is detrimental to the energy density. Therefore, controlling the thickness of the metal sheet within the aforementioned range is more conducive to achieving both energy density and safety performance in the battery cell.

[0174] For example, the thickness of the metal sheet is 0.15 mm to 0.4 mm, such as 0.15 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.24 mm, 0.26 mm, 0.28 mm, 0.3 mm, 0.32 mm, 0.34 mm, 0.36 mm, 0.38 mm, 0.4 mm, or a value within the range obtained by any combination of the above two values.

[0175] Figure 10 This is a schematic top view of a first cover body according to this application.

[0176] In some embodiments, such as Figure 6 and Figure 10 As shown, the first cover 1221 includes a first positive electrode through hole 3031 and a second positive electrode through hole 3032 arranged parallel to the third direction Z. The third direction Z is the width direction of the battery cell, and the third direction Z is perpendicular to the first direction X and the second direction Y.

[0177] Multiple positive electrode plates 13 of the electrode assembly 11 are stacked in a third direction Z.

[0178] Electrode assembly 11 includes a first electrode assembly 101 and a second electrode assembly 102. The first electrode assembly 101 includes a first positive electrode tab 1331, and the second electrode assembly 102 includes a second positive electrode tab 1332.

[0179] The first positive electrode tab 1331 extends out of the first positive electrode through hole 3031, and the second positive electrode tab 1332 extends out of the second positive electrode through hole 3032.

[0180] The electrode assembly includes a first electrode assembly and a second electrode assembly, which further improves the internal space utilization of the battery cell and increases its energy density. The first cover has a first tab lead-out hole and a second tab lead-out hole. Compared to directly welding the tab to the first cover, the first and second tab lead-out holes can fix the positive tab, preventing it from shaking, reducing the probability of it being pulled and broken, improving the connection stability between the positive tab and the positive end cover assembly, and helping to improve the safety performance of the battery cell.

[0181] In some embodiments, such as Figure 6 and Figure 10 As shown, the first cover 1221 has a first flat portion 60 and a first recess 70 recessed in the battery cell 10 along the first direction X. The first recess 70 is configured to accommodate at least a portion of the positive electrode tab 133 or metal sheet 50 passing through the tab outlet hole 303.

[0182] By providing a first recess on the first cover, space that can be accommodated for the positive electrode tab or metal sheet in the first direction can be saved, further improving the space utilization rate inside the battery cell, thereby increasing the energy density of the battery cell.

[0183] In some embodiments, such as Figure 6 As shown, the first recess 70 has a first surface 70a and a second surface 70b along the first direction X. The first surface 70a is the surface facing away from the electrode assembly 11, and the second surface 70b is the surface facing the electrode assembly 11. At least a portion of the positive electrode tab 133 is welded to the first surface 70a, or at least a portion of the metal sheet 50 is welded to the first surface 70a.

[0184] By passing the positive electrode tab through the tab lead-out hole and welding it to the first surface of the first recess away from the electrode assembly, the space for accommodating the tab in the first direction is saved, while also fixing the positive electrode tab and enhancing the connection stability between the positive electrode tab and the positive end cap assembly. This makes it easier for the battery cell to balance energy density and safety performance.

[0185] In some embodiments, such as Figure 11 As shown, the first straight portion 60 has a third surface 60a and a fourth surface 60b along the first direction X. The third surface 60a is located inside the battery cell 10, and the fourth surface 60b is located outside the battery cell 10. Along the first direction X, the distance between the main body portion and the third surface 60a is 8.0 mm to 13.0 mm. The distance between the main body portion and the third surface 60a is as follows... Figure 11 As shown in L7.

[0186] The distance between the main body and the third surface reflects the size of the tab space inside the battery cell. The larger the distance, the larger the tab space, and the lower the risk of the tab being inserted backwards into the main body. However, at the same time, the larger the space occupied inside the battery cell in the first direction, the less favorable it is for the energy density of the battery cell. Therefore, this application controls the value of L7 within the range of 8.0 mm to 13.0 mm, which is beneficial for the battery cell to balance energy density and safety performance.

[0187] For example, L7 is 8.0mm to 13.0mm, such as 8.0mm, 8.5mm, 9.0mm, 9.5mm, 10.0mm, 10.5mm, 11.0mm, 11.5mm, 12.0mm, 12.5mm, 13.0mm, or a value within the range obtained by any combination of the above two values.

[0188] In some embodiments, such as Figure 8 , Figure 11 As shown, the positive terminal cover assembly 122a includes a second cover 1222, and a first cover 1221 is welded to the second cover 1222. The second cover 1222 has a second flat portion 61 and a first protrusion 80 protruding outward from the battery cell in a first direction X. The first protrusion 80 is disposed opposite to the first surface 70a and is configured to accommodate at least a portion of the positive electrode tab 133 or metal sheet 50 passing through the tab lead-out hole 303.

[0189] The second cover facilitates the welding of the positive terminal cover assembly. By providing the first protrusion, the positive electrode tab or metal sheet welded to the first cover can be accommodated, and the first protrusion at the battery module level can function as a positive terminal, allowing multiple battery cells to converge through the electrical connection between the first protrusions.

[0190] In some embodiments, such as Figure 6 and Figure 10 As shown, the first cover 1221 also has a second recess 71 recessed into the battery cell 10 along the first direction X. The second recess 71 is used to accommodate the second straight portion 61 so that the first cover 1221 and the second cover 1222 are welded together.

[0191] The above configuration can increase the welding area between the first cover and the second cover, improve the welding precision and reliability, thereby improving the structural stability of the positive terminal cover assembly. The larger welding area is also more conducive to current flow, thus helping to improve the safety performance of the battery cell.

[0192] Figure 12 This is another partial schematic diagram of a single battery cell in this application.

[0193] In some embodiments, such as Figure 9 , Figure 12 As shown, the negative terminal cap assembly 122b includes a negative terminal 1224, and the negative terminal 1224 includes a negative terminal post 1224a;

[0194] The negative electrode plate 14 includes a negative electrode tab 141, which extends from the negative electrode plate 14 along the first direction X and is welded to the negative electrode post 1224a.

[0195] Alternatively, the negative electrode tab 141 extends from the negative electrode plate 14 along the first direction X and is welded to the negative electrode post 1224a through the busbar component 1225.

[0196] When the negative electrode post is directly welded to the negative electrode tab, it is more conducive to saving the internal space of the battery cell occupied by mechanical parts in the first direction, which helps to further improve the energy density of the battery cell.

[0197] In some embodiments, such as Figure 12 As shown, the negative terminal cap assembly 122b includes a third cap 1226, the third cap 1226 includes an electrode lead-out hole 401, and the negative terminal post 1224a passes through the electrode lead-out hole 401; the negative terminal cap assembly 122b includes a first insulating member 1227, which is disposed between the negative terminal 1224 and the third cap 1226 to insulate the negative terminal 1224 and the third cap 1226.

[0198] When the casing is positively charged, it is connected to the third cover of the negative terminal cover assembly, so the third cover is also positively charged. The negative terminal, connected to the negative electrode tab, is negatively charged. Therefore, by placing a first insulating element between the third cover and the negative terminal, short circuits between the positive and negative terminals can be effectively prevented, improving the safety performance of the battery cell.

[0199] In some embodiments, such as Figure 12 As shown, the first insulating member 1227 includes a third straight portion 62 and a third recess 72 disposed on one side facing the main body portion; the third recess 72 is configured to accommodate at least a portion of the negative electrode tab 141.

[0200] By providing a third recess on the first insulating member, it is beneficial to save space on the tabs on the negative electrode side, thereby further improving the energy density of the battery cell.

[0201] In some embodiments, the dimension of the third straight portion along the first direction is 4.5 mm to 8.0 mm.

[0202] A larger dimension of the third straight section along the first direction allows for more space to accommodate the negative electrode tab, which is beneficial for insulation between the negative electrode and the casing, but detrimental to the energy density of the battery cell. If the dimension of the third straight section along the first direction is too small, the main body may wobble within the casing along the first direction, pulling on the negative electrode tab and causing it to break, which is detrimental to the safety performance of the battery cell. Therefore, controlling the dimension of the third straight section within the range of 4.5mm to 8.0mm is more conducive to achieving a balance between energy density and safety performance in the battery cell.

[0203] For example, the dimension of the third straight portion along the first direction is 4.5mm to 8.0mm, such as 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, or a value within the range obtained by any combination of the above two values.

[0204] In some embodiments, such as Figure 12 As shown, the negative terminal 1224 includes the negative terminal post 1224a and the limiting part 1224b; the negative terminal post 1224a passes through the electrode lead-out hole 401, and the limiting part 1224b is connected to the negative terminal post 1224a; along the first direction X, the limiting part 1224b is located on the side of the third cover 1226 facing the electrode assembly 11, and the limiting part 1224b is configured to restrict the negative terminal post 1224a from disengaging from the electrode lead-out hole 401 in the direction away from the electrode assembly 11.

[0205] By setting a limiting part, the structural stability of the negative terminal cover assembly can be improved. In the first direction, the projected area of ​​the limiting part will be larger than the projected area of ​​the negative terminal post. This can increase the welding area between the negative terminal tab and the negative terminal, or increase the welding area between the current collector and the negative terminal, thereby improving the overcurrent capacity at the negative terminal cover assembly and helping to improve the safety performance of the battery cell.

[0206] In some embodiments, the busbar component has a sheet-like structure and a thickness of 0.6 mm to 1.2 mm.

[0207] By controlling the thickness of the busbar component within the range of 0.6mm to 1.2mm, the negative terminal cover assembly can have sufficient overcurrent capacity while reducing the impact of the busbar component on the energy density of the battery cell, thus enabling the battery cell to balance energy density and safety performance.

[0208] For example, the thickness of the busbar component is 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, or a value within the range obtained by any combination of the above two values.

[0209] In some embodiments, a first insulating film is provided between the main body and the housing, the first insulating film being used to insulate the main body and the housing.

[0210] In some embodiments, the first insulating film comprises one or more of polypropylene and polyethylene terephthalate. Selecting a first insulating film made of the aforementioned material is beneficial for improving the insulation between the electrode assembly and the housing.

[0211] When the casing is positively charged, the negative electrode in the electrode assembly will also cause a short circuit between the positive and negative electrodes once it comes into contact with the casing. Therefore, by setting a first insulating film between the main body and the casing, the short circuit between the positive and negative electrodes can be effectively prevented, thus improving the safety performance of the battery cell.

[0212] Figure 13 This is a schematic diagram of a second insulating film according to this application.

[0213] In some embodiments, such as Figure 12-13 As shown, a second insulating film 16 is disposed between the negative electrode tab 141 and the first insulating film (not shown in the figure). The second insulating film 16 covers the negative electrode tab 141 and extends to the space between the main body and the housing 121. The second insulating film is used to insulate the negative electrode tab 141 and the housing 121.

[0214] The material of the second insulating film can be, for example, PI, PET, or PP. Although not shown in the figure, it can be assumed that the surface of the main body is provided with the first insulating film. Figure 13 As shown, the second insulating film 16 has a slit corresponding to the negative electrode tab 141 so that the negative electrode tab 141 can pass through.

[0215] When the casing is positively charged, adding a second insulating film at the negative electrode tab can further reduce the probability of the negative electrode tab coming into contact with the casing, further prevent short circuits between the positive and negative electrodes, and improve the safety performance of the battery cell.

[0216] In some embodiments, the areal density of the positive electrode sheet on one side is 0.33 g / 1540.25 mm. 2 Up to 0.40g / 1540.25mm 2 .

[0217] If the areal density of the positive electrode sheet is too high, the more positive electrode active material is loaded on the positive electrode current collector per unit area, resulting in a higher energy density of the battery cell. However, this also increases the solid-phase lithium-ion transport distance, affecting lithium-ion kinetics and consequently the rate performance of the battery cell. Therefore, this application controls the areal density of the positive electrode sheet to be within 0.33 g / 1540.25 mm². 2 Up to 0.40g / 1540.25mm 2 Within this range, it is more conducive to improving the rate performance of high energy density battery cells.

[0218] For example, the areal density of the positive electrode sheet on one side is 0.33 g / 1540.25 mm.2 Up to 0.40g / 1540.25mm 2 For example, 0.33g / 1540.25mm 2 0.34g / 1540.25mm 2 0.35g / 1540.25mm 2 0.36g / 1540.25mm 2 0.37g / 1540.25mm 2 0.38g / 1540.25mm 2 0.39g / 1540.25mm 2 0.40g / 1540.25mm 2 , or its value is within the range obtained by combining any two of the above values.

[0219] In the embodiments of this application, the areal density of the positive electrode sheet can be detected using equipment and methods known in the art. For example, a single battery cell under test at 0% SOC is disassembled to obtain the positive electrode sheet. If it is a single-sided coated positive electrode sheet, 30 unit areas are randomly selected on the positive electrode sheet. The mass of the material other than the positive current collector on each unit area of ​​the positive electrode sheet is weighed, and the sum is divided by 30 to obtain the areal density of the positive electrode sheet under test. If it is a double-sided coated positive electrode sheet, the above test method is repeated after removing one side to measure the areal density of the positive electrode sheet under test. The negative electrode sheet is measured in the same way.

[0220] In some embodiments, when the cell is at 0% SOC, the compaction density of the positive electrode is 2.4 g / cm³. 3 Up to 2.7 g / cm 3 .

[0221] In this application, "compacted density" refers to the actual density of the film layer after the electrode has been rolled, which can be expressed as the mass of the material other than the current collector in a unit volume of the electrode.

[0222] A higher compaction density of the positive electrode sheet is more beneficial to the energy density of the battery cell. However, a lower porosity of the positive electrode sheet makes it more difficult for the electrolyte to wet the positive electrode active material, increases lithium-ion transport resistance, leads to a higher DCR (distribution rate cutoff) of the battery cell, and generates more heat during fast charging, which is detrimental to the rate performance and cycle performance of the battery cell. Therefore, this application controls the compaction density of the positive electrode sheet to 2.4 g / cm³. 3 Up to 2.7 g / cm 3 Within this range, it is more conducive to making battery cells take into account energy density, rate performance and cycle performance.

[0223] For example, the compaction density of the positive electrode sheet is 2.4 g / cm³. 3 Up to 2.7 g / cm 3 For example, 2.4 g / cm³ 3 2.45g / cm 3 2.5g / cm 3 2.55g / cm 3 2.6g / cm 3 2.65g / cm 3 2.7g / cm 3 , or its value is within the range obtained by combining any two of the above values.

[0224] In the embodiments of this application, the compaction density of the positive electrode sheet can be detected using equipment and methods known in the art. For example, a single battery cell under test at 0% SOC is disassembled to obtain the positive electrode sheet. Thirty unit areas are randomly selected from the positive electrode sheet under test. The mass m1 of the material (excluding the positive current collector) on each unit area of ​​the positive electrode sheet is weighed. The thickness H1 of the positive electrode sheet and the thickness H0 of the current collector are measured. The compaction density of each unit area of ​​the positive electrode sheet is calculated as m1 / (H1-H0). The compaction densities of the 30 unit areas of the positive electrode sheet are summed and then divided by 30 to obtain the compaction density of the positive electrode sheet under test. The measurement deviation of the compaction density is within ±0.05 g / cm³. 3 Within the range. The same applies to the negative electrode.

[0225] In some embodiments, the thickness of the positive current collector is 12 μm to 15 μm.

[0226] The greater the thickness of the positive electrode current collector, the more space it occupies within the battery cell, which is detrimental to the energy density of the battery cell. Conversely, if the thickness of the positive electrode current collector is too small, the mechanical strength of the positive electrode sheet is insufficient, making it prone to breakage during battery cycling, which is detrimental to the safety performance of the battery cell. Therefore, this application controls the thickness of the positive electrode current collector within the range of 12μm to 15μm, which is more conducive to achieving a balance between energy density and safety performance in the battery cell.

[0227] For example, the thickness of the positive current collector is 12 μm to 15 μm, such as 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, or a value within the range obtained by any combination of the above two values.

[0228] In some embodiments, the ratio of the thickness of the positive current collector to the total thickness of the positive electrode sheet is 4.5% to 7%.

[0229] In this application, the ratio of the thickness of the positive current collector to the total thickness of the positive electrode sheet is controlled within the range of 4.5% to 7%, which enables the positive electrode sheet to load more positive active material and further improve the energy density of the battery cell.

[0230] For example, the ratio of the thickness of the positive current collector to the total thickness of the positive electrode sheet is 4.5% to 7.0%, such as 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5.0%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, 6.0%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9%, 7.0%, or a value within the range obtained by any combination of the above two values.

[0231] In some examples, the ratio of the thickness of the positive current collector to the total thickness of the positive electrode sheet can be calculated by disassembling a battery cell at 0% SOC, obtaining the positive electrode sheet, and measuring the average thickness of the positive current collector and the positive electrode film. In this application, a battery cell that discharges to a cutoff voltage of 2.0V at 0.05C is considered a battery cell at 0% SOC.

[0232] In some embodiments, the positive electrode active material includes lithium transition metal phosphate.

[0233] In this article, "lithium transition metal phosphates" refers to a class of salts that include lithium, transition metal elements, and phosphate ions. Examples include lithium iron phosphate and lithium manganese iron phosphate. Lithium transition metal oxide materials include lithium-containing nickel-cobalt-manganese oxides (NCM) and lithium-containing nickel-cobalt-aluminum oxides (NCA). Lithium transition metal phosphates typically have stable crystal structures, and phosphate ions can form a framework structure through covalent bonds, exhibiting good stability in redox reactions.

[0234] The positive electrode active material in the positive electrode film and the negative electrode active material in the negative electrode film can be detected using methods known in the art. In one example, the battery cell under test is disassembled to obtain the positive and negative electrode sheets. The binder is washed away with NMP, and then the types of positive and negative electrode active materials can be obtained using X-ray diffraction (XRD) and scanning electron microscopy (SEM). For example, the characteristic peaks of the positive electrode active material can be obtained by XRD. After excluding the characteristic peaks of the conductive agent, the type of positive electrode active material can be determined by comparing the remaining characteristic peaks. Exemplarily, XRD testing can be performed under the following conditions: the powder is placed on the sample stage, compacted with a glass slide, and placed in an XRD testing instrument: tube voltage 40 kV, tube current 20 mA, Cu target, scan rate 2,000 (d•min). -1 The scanning range is 10°-80°.

[0235] In some embodiments, the areal density of the negative electrode sheet on one side is 0.130 g / 1540.25 mm. 2 Up to 0.175g / 1540.25mm 2 .

[0236] If the areal density of the negative electrode sheet is too high, the more negative electrode active material is loaded on the negative electrode current collector per unit area, resulting in a higher energy density of the battery cell. However, this also leads to a longer lithium-ion solid-phase transport distance, affecting the rate performance of the battery cell. Therefore, this application controls the areal density of the negative electrode sheet to be within 0.130 g / 1540.25 mm². 2 Up to 0.175g / 1540.25mm 2 Within this range, it is more conducive to enabling individual battery cells to balance energy density and rate performance.

[0237] For example, the areal density of the negative electrode sheet is 0.130 g / 1540.25 mm. 2 Up to 0.175g / 1540.25mm 2 For example, 0.130g / 1540.25mm 2 0.135g / 1540.25mm 2 0.140g / 1540.25mm 2 0.145g / 1540.25mm 2 0.150g / 1540.25mm 2 0.155g / 1540.25mm 2 0.160g / 1540.25mm 2 0.165g / 1540.25mm2 0.175g / 1540.25mm 2 , or its value is within the range obtained by combining any two of the above values.

[0238] In some embodiments, when the battery cell is at 0% SOC, the compaction density of the negative electrode sheet is 1.37 g / cm³. 3 Up to 1.55 g / cm 3 .

[0239] A higher compaction density of the negative electrode sheet is more beneficial to the energy density of the battery cell. However, a lower porosity of the negative electrode sheet makes it more difficult for the electrolyte to wet the sheet, which is detrimental to the rate performance of the battery cell. Therefore, this application controls the compaction density of the negative electrode sheet to 1.37 g / cm³. 3 -1.55g / cm 3 Within this range, it is more conducive to enabling individual battery cells to balance energy density and rate performance.

[0240] For example, the compaction density of the negative electrode sheet is 1.37 g / cm³. 3 Up to 1.55 g / cm 3 For example, 1.37 g / cm³ 3 1.38g / cm 3 1.40 g / cm 3 1.42g / cm 3 1.44 g / cm 3 1.46 g / cm 3 1.48g / cm 3 1.50g / cm 3 1.52 / cm 3 1.54g / cm 3 1.55g / cm 3 , or its value is within the range obtained by combining any two of the above values.

[0241] In some embodiments, the thickness of the negative electrode current collector is 4 μm to 7 μm.

[0242] The greater the thickness of the negative electrode current collector, the more space it occupies within the battery cell, which is detrimental to the energy density of the battery cell. Conversely, if the thickness of the negative electrode current collector is too small, the mechanical strength of the negative electrode sheet is insufficient, making it prone to breakage during battery cycling, which is detrimental to the cycle performance of the battery cell. Therefore, this application controls the thickness of the negative electrode current collector within the range of 4μm to 7μm, which is more conducive to achieving a balance between energy density and cycle performance in the battery cell.

[0243] For example, the thickness of the negative electrode current collector is 4 μm to 7 μm, such as 4 μm, 4.2 μm, 4.4 μm, 4.6 μm, 4.8 μm, 5 μm, 5.2 μm, 5.4 μm, 5.6 μm, 5.8 μm, 6 μm, 6.2 μm, 6.4 μm, 6.6 μm, 6.8 μm, 7 μm, or a value within the range obtained by any combination of the above two values.

[0244] In some embodiments, the ratio of the thickness of the negative current collector to the total thickness of the negative electrode sheet is 2% to 6%.

[0245] A higher ratio of the thickness of the negative electrode current collector to the total thickness of the negative electrode sheet allows for a greater amount of negative electrode active material loaded on the negative electrode sheet, which is beneficial for improving the energy density of the battery cell. However, it also increases the difficulty of electrolyte wetting of the negative electrode sheet, affecting lithium-ion kinetics and thus the rate performance of the battery cell. Therefore, this application controls the ratio of the thickness of the negative electrode current collector to the total thickness of the negative electrode sheet to be between 2% and 6%, which is more conducive to achieving both energy density and rate performance in the battery cell.

[0246] For example, the ratio of the thickness of the negative current collector to the total thickness of the negative electrode sheet is 2% to 6%, for example, 2%, 3%, 4%, 5%, 6%, or a value within the range obtained by any combination of the above two values.

[0247] In some embodiments, the negative electrode active material includes graphite material, which includes one or more of artificial graphite and natural graphite.

[0248] Artificial graphite and natural graphite can be distinguished by SEM cross-sectional images taken by scanning electron microscope (SEM). Natural graphite has gaps between the sheet-like structures in its SEM cross-section, while artificial graphite has a dense structure with no obvious gaps. Alternatively, they can be distinguished by XRD patterns obtained by X-ray diffraction. Natural graphite has obvious 2H and 3R phases in its XRD pattern, while artificial graphite only has the 2H phase in its XRD pattern.

[0249] In some embodiments, an isolation membrane is disposed between the electrode plates. The isolation membrane includes a base film and a coating disposed on at least one side of the base film. The coating includes inorganic particles.

[0250] In some embodiments, the base film includes one or more of polypropylene (PP) film and polyethylene (PE) film.

[0251] Optionally, the base film can be a single-layer film or a multi-layer composite film. When the base film is a multi-layer composite film, the materials of each layer can be the same or different.

[0252] In some embodiments, the inorganic particles include one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide.

[0253] By providing a coating containing inorganic particles on at least one side of the separator, the insulation of the separator can be improved, the probability of short circuit between the positive and negative electrodes can be reduced, thereby reducing the risk of thermal runaway of the battery cell and helping to improve the safety performance of the battery cell.

[0254] In some embodiments, the coating further includes an adhesive, which includes one or more of fluorinated adhesives or polyacrylic adhesives. Specifically, the fluorinated adhesive includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, and tetrafluoroethylene-hexafluoropropylene copolymer. The polyacrylic adhesive includes one or more of polyacrylic acid and fluorinated acrylate resins.

[0255] In some embodiments, the thickness of the base film is 5 μm to 9 μm.

[0256] A thicker base film generally improves the safety performance of the battery cell, but it can negatively impact the lithium-ion transport efficiency between the positive and negative electrodes, thus affecting lithium-ion kinetics and hindering the rate performance of the battery cell. Furthermore, it increases the mass and volume percentage of inactive materials within the battery cell, negatively impacting its energy density. Therefore, controlling the base film thickness within a suitable range is more effective in improving the rate performance of the battery cell while simultaneously maintaining its energy density and safety.

[0257] For example, the thickness of the base film is 5 μm to 9 μm, such as 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, or a value within the range obtained by any combination of the above two values.

[0258] In some embodiments, the coating thickness is 1 μm to 5 μm.

[0259] A thicker coating increases the mechanical strength of the separator, making it less susceptible to lithium dendrite puncture and thus improving the safety performance of individual battery cells. However, a thicker coating can negatively impact the energy density of individual battery cells and the lithium-ion transport efficiency between the positive and negative electrodes, thus affecting the rate performance of the battery cells. Therefore, controlling the coating thickness within a suitable range is more effective in improving the rate performance of individual battery cells while maintaining their energy density and safety performance.

[0260] For example, the thickness of the coating is from 1 μm to 5 μm, such as 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, or a value within the range obtained by any combination of the above two values.

[0261] The thickness settings of the aforementioned base film, separator, and coating are beneficial for ensuring that the battery cell balances energy density and safety performance.

[0262] In the embodiments of this application, the thickness of the membrane layer has a meaning known in the art. It can be detected using a meaning and equipment known in the art. For example, a newly prepared separator can be taken as a sample, or a battery cell that has been completely discharged (discharged to the discharge cutoff voltage so that the charge state of the battery cell is about 0% SOC) can be disassembled in reverse, the separator can be obtained from the battery cell, and the separator can be dried and used as a sample. The separator can be cut with an ion beam cutter to form a cross section. Subsequently, the thickness of the separator and its various layers can be measured using a scanning electron microscope.

[0263] In some embodiments, the battery cell includes an electrolyte, which includes a lithium salt, and the lithium salt includes one or more of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate.

[0264] In some embodiments, the electrolyte comprises lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, wherein the mass fraction of lithium bis(fluorosulfonyl)imide is greater than or equal to the mass fraction of lithium hexafluorophosphate based on the total mass of the electrolyte.

[0265] Lithium hexafluorophosphate (LiPF6) possesses higher ionic conductivity and good thermal stability, making it widely used in electrolytes for battery cells. However, the water of crystallization in the positive electrode active material readily reacts with LiPF6 to form hydrofluoric acid, which in turn corrodes the positive electrode current collector and the battery cell casing. Therefore, this application addresses this issue by simultaneously including both LiPF6 and lithium bis(fluorosulfonyl)imide in the electrolyte and controlling the proportion of lithium bis(fluorosulfonyl)imide in the lithium salt. This improves the corrosion of the current collector and casing by the lithium salt, further enhancing the safety performance of high-energy-density battery cells.

[0266] In the embodiments of this application, the types and contents of inorganic components / electrolyte lithium salts in the electrolyte are known in the art and can be detected using equipment and methods known in the art. For example, the inorganic components / electrolyte lithium salts in the electrolyte can be qualitatively or quantitatively analyzed by referring to standards JY / T 0575-2020 "General Rules for Ion Chromatography Analysis" and GB / T 6040-2019 "General Rules for Infrared Spectroscopy Analysis". In the embodiments of this application, freshly prepared electrolyte can be used as a sample, the free electrolyte of a fresh battery can be used as a sample, or a fully discharged battery cell (discharged to the discharge cutoff voltage so that the charge state of the battery cell is about 0% SOC) can be disassembled in reverse, and the free electrolyte obtained from the battery cell can be used as a sample for detection.

[0267] In the embodiments of this application, the types and contents of organic components in the electrolyte are known in the art and can be detected using equipment and methods known in the art. For example, the organic components of the electrolyte can be qualitatively and quantitatively analyzed by gas chromatography using GB / T 9722-2023 "General Rules for Gas Chromatography of Chemical Reagents".

[0268] After detecting the mass fraction of each component in the electrolyte, the ratio of the mass fraction of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate can be calculated.

[0269] In some embodiments, the mass fraction of lithium bis(fluorosulfonyl)imide is 5 wt% to 12 wt%; optionally, it is 8 wt% to 12 wt%.

[0270] For example, the mass fraction of lithium bis(fluorosulfonyl)imide in the electrolyte is 8 wt% to 12 wt%, such as 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, 10.5 wt%, 11 wt%, 11.5 wt%, 12 wt%, or a value within the range obtained by any combination of the above two values.

[0271] A low mass fraction of lithium difluorosulfonylimide in the electrolyte is insufficient to improve the electrolyte's ionic conductivity and thus the rate performance of the battery cells. Conversely, an excessively high mass fraction of lithium difluorosulfonylimide in the electrolyte can easily react with the positive electrode current collector and casing, leading to corrosion of these components and compromising the safety performance of the battery cells. Therefore, controlling the mass fraction of lithium difluorosulfonylimide in the electrolyte within a suitable range is beneficial for both improving the rate performance and ensuring the safety of the battery cells.

[0272] In some embodiments, the mass fraction of lithium hexafluorophosphate is 4.5 wt% to 8 wt% based on the total mass of the electrolyte.

[0273] If the mass fraction of lithium hexafluorophosphate in the electrolyte is too low, the mass fraction of lithium difluorosulfonylimide will be too high, which is detrimental to the safety performance of the battery cell. Conversely, if the mass fraction of lithium hexafluorophosphate in the electrolyte is too high, it can easily corrode the positive electrode current collector and casing during battery cell cycling and storage, also negatively impacting the battery cell's safety performance. Therefore, this application aims to control the mass fraction of lithium hexafluorophosphate in the electrolyte within a suitable range, which is more conducive to improving the rate performance of the battery cell while maintaining its safety performance.

[0274] For example, the mass fraction of lithium hexafluorophosphate is 4.5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, or a value within the range obtained by any combination of the above two values, based on the total mass of the electrolyte.

[0275] In some embodiments, the mass fraction of lithium salt is 15 wt% to 20 wt% based on the total mass of the electrolyte.

[0276] If the mass fraction of lithium salt in the electrolyte is too low, it will hinder the improvement of the electrolyte's ionic conductivity and fail to improve the lithium-ion kinetics within the battery cell. Conversely, if the mass fraction of lithium salt in the electrolyte is too high, it will increase the electrolyte's viscosity, which will negatively impact lithium-ion transport in the liquid phase and thus affect lithium-ion kinetics. Therefore, this application improves the ionic conductivity of the electrolyte by controlling the mass fraction of lithium salt in the electrolyte within the range of 15wt% to 20wt%, thereby enhancing lithium-ion transport in the liquid phase and improving lithium-ion kinetics, ultimately helping to improve the rate performance of high-energy-density battery cells.

[0277] For example, the mass fraction of lithium salt is 15 wt% to 20 wt% based on the total mass of the electrolyte, such as 15 wt%, 15.5 wt%, 16 wt%, 16.5 wt%, 17 wt%, 17.5 wt%, 18 wt%, 18.5 wt%, 19 wt%, 19.5 wt%, 20 wt%, or a value within the range obtained by any combination of the above two values.

[0278] In some embodiments, the ionic conductivity of the electrolyte at room temperature is 9.0 mS / cm to 13 mS / cm.

[0279] A higher ionic conductivity in the electrolyte facilitates the rapid migration of lithium ions, thus improving the rate performance of individual battery cells. The upper limit of the electrolyte's ionic conductivity is limited by its components, including their proportions, solvents, lithium salts, and additives. "Room temperature" refers to a temperature range of 20-30℃.

[0280] For example, the ionic conductivity of the electrolyte at room temperature is 9.0 mS / cm to 13 mS / cm, such as 9.0 mS / cm, 9.5 mS / cm, 10.0 mS / cm, 10.5 mS / cm, 11.0 mS / cm, 11.5 mS / cm, 12.0 mS / cm, 12.5 mS / cm, 13.0 mS / cm, or a value within the range obtained by any combination of the above two values.

[0281] The ionic conductivity of an electrolyte at room temperature can be detected using methods known to those skilled in the art. In one example, after disassembling a battery cell at 0% SOC to obtain the electrolyte to be tested, the ionic conductivity of the electrolyte to be tested is measured using a conductivity meter in accordance with HG / T 4067-2015.

[0282] In some embodiments, the electrolyte comprises a cyclic carbonate solvent, which includes one or more of ethylene carbonate, propylene carbonate, and fluoroethylene carbonate. Optionally, the cyclic carbonate solvent includes ethylene carbonate.

[0283] Cyclic carbonate solvents have a high dielectric constant, which is beneficial for the dissociation of lithium salts in the electrolyte, thereby improving the ionic conductivity of the electrolyte, enhancing the liquid phase transport of lithium ions, improving the lithium ion kinetics inside the battery cell, and improving the rate performance of high energy density battery cells.

[0284] In some embodiments, the mass fraction of the cyclic carbonate solvent is 15wt%-30wt% based on the total mass of the electrolyte.

[0285] A higher mass fraction of cyclic carbonates in the electrolyte is more conducive to the dissociation of lithium salts and helps improve the ionic conductivity of the electrolyte. However, it also increases the viscosity of the electrolyte. When the mass fraction of cyclic carbonates in the electrolyte is too high, it is actually detrimental to the liquid-phase migration of lithium ions. Therefore, this application controls the mass fraction of cyclic carbonates in the electrolyte within the range of 15wt%-30wt%, which is more conducive to improving the liquid-phase transport of lithium ions and improving the rate performance of high-energy-density battery cells.

[0286] For example, the mass fraction of the cyclic carbonate solvent in the electrolyte is 15wt%-30wt%, such as 15wt%, 16wt%, 18wt%, 20wt%, 22wt%, 24wt%, 26wt%, 28wt%, 30wt%, or a value within the range obtained by any combination of the above two values.

[0287] In some embodiments, the electrolyte includes linear carbonate solvents, such as dimethyl carbonate and ethyl methyl carbonate.

[0288] Linear carbonate solvents have lower viscosity than cyclic carbonate solvents and can also promote the dissociation of lithium ions. Therefore, introducing linear carbonate solvents into the electrolyte can also help improve the ionic conductivity of the electrolyte, enhance the liquid phase transport of lithium ions, and improve the rate performance of high energy density battery cells.

[0289] In some embodiments, the mass fraction of dimethyl carbonate is 20wt%-35wt% based on the total mass of the electrolyte.

[0290] For example, the mass fraction of dimethyl carbonate in the electrolyte is 20wt%-35wt%, such as 20wt%, 22wt%, 24wt%, 26wt%, 28wt%, 30wt%, 32wt%, 34wt%, 35wt%, 40wt%, or a value within the range obtained by any combination of the above two values.

[0291] Linear carbonate solvents are beneficial for reducing electrolyte viscosity and improving ionic conductivity, but compared to cyclic carbonate solvents, they are more prone to side reactions and gas generation, affecting the cycle life of battery cells. Therefore, the mass fraction of dimethyl carbonate in the electrolyte needs to be controlled within an appropriate range. A mass fraction of 20wt%-35wt% is more conducive to improving the ionic conductivity of the electrolyte while reducing the probability of decomposition and gas generation, allowing high-energy-density battery cells to achieve both rate performance and cycle life.

[0292] In some embodiments, the electrolyte includes: an additive, which includes carbonate additives, specifically one or more of vinylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, trifluoromethyl ethylene carbonate, ethyleneene carbonate, and allyl ethylene carbonate. Optionally, the carbonate additive includes one or more of vinylene carbonate and fluoroethylene carbonate.

[0293] The aforementioned carbonate additives can participate in the formation of a stable solid electrolyte interface (SEI) film on the negative electrode side, increasing the organic components in the SEI film and giving it good toughness, thereby improving its reliability. Among them, vinylene carbonate helps inhibit solvent molecule intercalation, improving SEI film stability and enhancing the safety performance of high-energy-density battery cells. Fluorinated ethylene carbonate can generate a fluorine-rich SEI film, which helps reduce SEI film impedance, thereby reducing the rate response ratio (DCR) of the battery cell and improving the rate performance of high-energy-density battery cells.

[0294] In some embodiments, the mass fraction of vinylene carbonate is 0.01 wt% to 5 wt% based on the total mass of the electrolyte; optionally, it is 1 wt% to 2.5 wt%.

[0295] For example, the mass fraction of vinylene carbonate in the electrolyte is 0.01wt%-5wt%, such as 0.01wt%, 0.05wt%, 0.1wt%, 0.15wt%, 0.2wt%, 0.5wt%, 1wt%, 1.2wt%, 1.4wt%, 1.6wt%, 1.8wt%, 2wt%, 2.2wt%, 2.4wt%, 2.5wt%, 2.6wt%, 2.8wt%, 3wt%, 3.2wt%, 3.4wt%, 3.6wt%, 3.8wt%, 4wt%, 4.2wt%, 4.4wt%, 4.6wt%, 4.8wt%, 5wt%, or a value within the range obtained by any combination of the above two values.

[0296] If the mass fraction of vinylene carbonate is too small, it cannot improve the stability of the SEI layer; if the mass fraction of vinylene carbonate is too large, the electrolyte viscosity increases, which is not conducive to lithium-ion liquid-phase transport and is more likely to react with the negative electrode and generate gas, which is detrimental to the safety performance of the battery cell. Therefore, this application controls the mass fraction of vinylene carbonate in the electrolyte within the range of 0.01wt%-5wt%, which is more conducive to improving the reliability of the SEI film, reducing side reactions in the battery cell, and improving the safety performance of the battery cell.

[0297] In some embodiments, the mass fraction of fluoroethylene carbonate is 0.01 wt% to 4 wt%, optionally 0.1 wt% to 0.5 wt%, based on the total mass of the electrolyte.

[0298] For example, the mass fraction of fluoroethylene carbonate in the electrolyte is 0.01wt%-4wt%, such as 0.01wt%, 0.05wt%, 0.1wt%, 0.15wt%, 0.2wt%, 0.5wt%, 1wt%, 1.2wt%, 1.4wt%, 1.6wt%, 1.8wt%, 2wt%, 2.2wt%, 2.4wt%, 2.5wt%, 2.6wt%, 2.8wt%, 3wt%, 3.2wt%, 3.4wt%, 3.6wt%, 3.8wt%, 4wt%, or a value within the range obtained by any combination of the above two values.

[0299] If the mass fraction of fluoroethylene carbonate is too small, it cannot effectively reduce the rate-return ratio (DCR) of individual battery cells; if the mass fraction is too large, fluoroethylene carbonate easily decomposes to generate substances such as HF, which can react with the negative electrode, corroding the SEI film and the positive electrode current collector, thus negatively impacting the stability of the SEI film and the positive electrode. Therefore, this application controls the mass fraction of vinylene carbonate in the electrolyte within the range of 0.01wt%-4wt%, which is more conducive to reducing the DCR of individual battery cells and improving the rate performance and safety performance of high-energy-density battery cells.

[0300] Adding certain substances, such as additives, to the electrolyte can have a significant impact. Because these additives participate in the film formation on the surface of active materials, their content in the electrolyte of a single battery cell varies depending on the formation process, the battery's lifespan, and its storage condition. Therefore, the additive content in freshly prepared electrolyte may differ from that in electrolyte obtained from reverse-engineered batteries. However, those skilled in the art can determine the approximate range of the relevant substances' content in the fresh electrolyte based on the battery cell's performance characteristics (e.g., cycle count) and residual content. Similarly, those skilled in the art can determine the approximate range of the additive content in non-freshly prepared (i.e., reverse-engineered) electrolytes based on the additive content in freshly prepared electrolytes, considering the battery cell's performance requirements and storage environment.

[0301] Therefore, the additive content mentioned in the technical solution of this application can be the content of additives actively added to fresh electrolyte, or the content of residual additives detected by reverse detection based on the actual battery state.

[0302] For example, the mass fraction of carbonate additives in the electrolyte is 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, or 8.5wt%, or its value is within the range obtained by any combination of the above two values.

[0303] For example, the mass fraction of carbonate additives in the electrolyte is 2wt%-8wt%, which can be understood as the mass fraction of carbonate additives in freshly prepared electrolyte. When the mass content of carbonate additives is within the above range, it can more effectively improve the cycle life of battery cells.

[0304] For example, the mass fraction of carbonate additives in the electrolyte is 0.5wt%-6wt%. This can be understood as obtaining the mass fraction of carbonate additives in the electrolyte of the battery cell after formation. When the mass content of carbonate additives is within the above range, it can more effectively improve the cycle life of the battery cell.

[0305] As the cycle and storage time of battery cells increases, carbonate additives are continuously consumed, and their mass fraction in the electrolyte shows a decreasing trend. In some embodiments, the mass fraction of carbonate additives changes at different life stages of the battery cell as follows:

[0306] In fresh electrolyte, if the mass fraction of carbonate additives is 2 wt%; within 3 months of storage in the battery cell storage compartment, the mass fraction of carbonate additives is approximately 0.85 wt%; within 3-6 months of storage in the battery cell storage compartment, the mass fraction of carbonate additives is approximately 0.63 wt%; and within 3-6 months of storage in the battery cell storage compartment, the mass fraction of carbonate additives is approximately 0.5 wt%.

[0307] In fresh electrolyte, the mass fraction of carbonate additives is 8 wt%; within 3 months of storage in the battery cell storage compartment, the mass fraction of carbonate additives is approximately 5.8 wt%; within 3-6 months of storage in the battery cell storage compartment, the mass fraction of carbonate additives is approximately 5.4 wt%; and within 3-6 months of storage in the battery cell storage compartment, the mass fraction of carbonate additives is approximately 5.1 wt%.

[0308] In some embodiments, the dimensions of the battery cell along the first direction are 230 mm to 350 mm.

[0309] In this application, the dimension of a battery cell along the first direction refers to the dimension of the battery cell's casing along the first direction, which can be understood as the length of the battery cell. When the dimension of the battery cell along the first direction meets the above-mentioned range, the size of the battery cell will not be too short, and the energy density of the battery cell will be high; the size of the battery cell will not be too long, resulting in a relatively short electron transport path, which is beneficial to improving the rate performance of the battery cell, thereby enabling the battery cell to achieve both high energy density and rate performance.

[0310] For example, the size of the battery cell along the first direction is 230mm to 350mm, such as 230mm, 240mm, 250mm, 260mm, 270mm, 280mm, 290mm, 300mm, 310mm, 320mm, 330mm, 340mm, 350mm, or a value within the range obtained by any combination of the above two values.

[0311] In some embodiments, the dimensions of the battery cell along the second direction are 100 mm to 130 mm.

[0312] In this application, the dimension of a battery cell along the second direction refers to the dimension of the battery cell's casing along the second direction, which can be understood as the width or height of the battery cell. When the dimension of the battery cell along the second direction meets the above-mentioned range, the size of the battery cell will not be too short, and the energy density of the battery cell will be high; the size of the battery cell will not be too tall, resulting in a relatively short electron transport path, which is beneficial to improving the rate performance of the battery cell, thereby enabling the battery cell to achieve both high energy density and rate performance.

[0313] For example, the size of the battery cell along the second direction is 100mm to 130mm, such as 100mm, 105mm, 110mm, 115mm, 120mm, 125mm, 130mm, or a value within the range obtained by any combination of the above two values.

[0314] In some embodiments, the dimensions of a single battery cell along a third direction are 23 mm to 50 mm.

[0315] In this application, the dimension of a battery cell along a third direction refers to the dimension of the battery cell casing along a third direction, which can be understood as the thickness of the battery cell. When the dimension of the battery cell along the third direction meets the above-mentioned range, the size of the battery cell will not be too thin, allowing for a greater number of electrode components to be installed inside the battery cell, and improving its mechanical strength in the third direction, which is beneficial to the energy density and safety performance of the battery cell; the size of the battery cell will not be too thick, making it more difficult for the electrolyte to wet the motor components in the thickness direction, which is detrimental to the rate performance of the battery cell, thus enabling the battery cell to achieve a balance of high energy density, good safety performance, and rate performance.

[0316] For example, the dimensions of a single battery cell along a third direction are 23mm to 50mm, such as 23mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, or values ​​within the range obtained by any combination of the above two values.

[0317] In some embodiments, the dimensions of the main body portion are 225 mm to 235 mm along the first direction.

[0318] If the size of the main body in the first direction is too large, it is easily deformed by compression, which can lead to lithium plating and, in severe cases, cause a short circuit between the positive and negative electrodes. If the size of the main body in the first direction is too small, it is detrimental to the energy density of the battery cell. Therefore, this application, by controlling the size of the main body in the first direction within the above-mentioned range, is more conducive to enabling the battery cell to achieve both energy density and safety performance.

[0319] For example, the size of the main body portion along the first direction is 225mm to 235mm, such as 225mm, 226mm, 227mm, 228mm, 229mm, 230mm, 231mm, 232mm, 233mm, 234mm, 235mm, or a value within the range obtained by any combination of the above two values.

[0320] In some embodiments, such as Figure 1 As shown, the battery cell 10 includes a pressure relief mechanism 40, which is disposed on the first wall 121a of the housing 121. The thickness of the first wall 121a is 1.2 mm to 1.5 mm.

[0321] In some embodiments, the thickness of the other walls of the housing 121 is 0.5 mm to 0.7 mm.

[0322] This application achieves "thermal-electric separation" by placing the pressure relief mechanism on the housing of the battery cell rather than on the end cap assembly. This prevents the battery cell from affecting the input or output of current during thermal runaway and prevents the material discharged by the pressure relief mechanism from directly splashing onto the electrode terminals, thus avoiding short circuits at the battery module level.

[0323] By making the thickness of the first wall where the pressure relief mechanism is located greater, the mechanical strength of the wall where the pressure relief mechanism is located can be improved. This prevents the first wall from damaging the walls around the pressure relief mechanism when the pressure relief mechanism releases waste, thus avoiding more serious safety problems. As a result, the safety performance of the battery cell can be improved.

[0324] In this application, a pressure relief mechanism refers to a component or part that is activated when the internal pressure or temperature of a battery cell reaches a predetermined threshold, in order to release the internal pressure or temperature. The design of this threshold varies depending on design requirements. This threshold may depend on the materials of one or more of the positive electrode, negative electrode, electrolyte, and separator in the battery cell.

[0325] The term "actuation" as used in this application refers to the activation or actuation of the pressure relief mechanism to a certain state, thereby releasing the internal pressure and temperature of the battery cell. The actions of the pressure relief mechanism may include, but are not limited to, at least a portion of the mechanism rupturing, breaking, tearing, or opening. When the pressure relief mechanism is activated, the high-temperature, high-pressure substances inside the battery cell are discharged as waste from the activated portion. This method allows for pressure and temperature relief of the battery cell under controllable pressure or temperature, thereby preventing potentially more serious accidents.

[0326] The emissions from battery cells mentioned in this application include, but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of the separator, high-temperature and high-pressure gases generated by the reaction, flames, etc.

[0327] For example, the thickness of the first wall is 1.2 mm to 1.5 mm, such as 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, or a value within the range obtained by any combination of the above two values.

[0328] In some embodiments, the lithium transition metal phosphate particles include a positive electrode coating layer, which includes carbon elements.

[0329] Next, using a single lithium-ion battery cell as a specific example, a detailed description of the positive electrode, negative electrode, separator, and electrolyte within the cell will be provided. It should be understood that the lithium-ion battery is merely an example, and the solution provided in this application can also be applied to other types of secondary batteries, such as sodium-ion batteries, magnesium-ion batteries, and lithium-sulfur batteries.

[0330] [Negative electrode plate]

[0331] A negative electrode typically includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector. The negative electrode film layer includes a negative electrode active material, such as graphite.

[0332] In some embodiments, the mass fraction of the negative electrode active material in the negative electrode active material layer is 96.5 wt% to 98.5 wt%, for example 96.5 wt%, 97 wt%, 97.5 wt%, 98 wt%, 98.5 wt%, or any range of two of the above values.

[0333] When the mass fraction of the negative electrode active material in the negative electrode active material layer meets the above range, the capacity of the negative electrode active material layer can be increased, thereby improving the energy density of the battery cell.

[0334] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0335] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymeric material substrate and a metal layer formed on at least one surface of the polymeric material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymeric material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0336] In some embodiments, in addition to the negative electrode active materials mentioned in the foregoing embodiments, negative electrode active materials known in the art for use in batteries may also be used. As an example, the negative electrode active material may include at least one of the following materials: tin-based materials, lithium titanate, etc. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0337] In the embodiments of this application, the graphite particles can be prepared using methods known in the art. Taking artificial graphite as an example, the preparation method includes: providing artificial graphite and an organic carbon source, mixing the two, and then carbonizing them to form a negative electrode coating layer on at least a portion of the surface of the artificial graphite particles.

[0338] In one embodiment, the negative electrode film layer further includes an adhesive. The adhesive may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0339] In some embodiments, the negative electrode film layer further includes a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0340] In some embodiments, the negative electrode film layer also includes other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0341] In some embodiments, the negative electrode sheet can be prepared by forming a negative electrode slurry using the components described above. For example, the negative electrode active material, conductive agent, binder, and any other components are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a negative electrode slurry. The negative electrode slurry is then coated onto a negative electrode current collector, and after drying, cold pressing, and other processes, the negative electrode sheet is obtained.

[0342] [Positive electrode plate]

[0343] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. The positive electrode film layer includes a positive electrode active material, which includes lithium transition metal phosphate.

[0344] In some embodiments, the mass fraction of lithium phosphate, based on the total mass of the positive electrode film, is 96.8 wt% to 97.8 wt%, for example 96.8 wt%, 97 wt%, 97.5 wt%, 97.8 wt%, or a range consisting of any two of the above values.

[0345] In this application embodiment, the mass fraction of the positive electrode active material has a meaning known in the art and can be detected using equipment and methods known in the art. For example, after discharging the battery cell to 0% state of charge (SOC), the positive electrode sheet is disassembled (if it is a double-sided coated electrode sheet, the positive electrode active material layer on one side can be wiped off first), and the mass fraction of the positive electrode active material in the positive electrode active material layer is calculated according to the following steps:

[0346] Step 1: Weigh the container and filter membrane together to get the total weight m0;

[0347] Step 2: Mix n positive electrode sheets with a total mass of m2 in a container with 25wt% concentrated hydrochloric acid. The mass ratio of the positive electrode sheets to the concentrated hydrochloric acid is 1:8. Then, place the container on a heating plate and perform a single heating digestion at 180℃ for 20 minutes to obtain a single digestion solution with a volume of approximately 2.5mL. Filter the single digestion solution using a filter membrane under vacuum and rinse the filter residue with 200mL of water to obtain the rinsed filter residue. Weigh the single positive electrode current collector with the positive active material layer removed as m1.

[0348] Step 3: Mix the filter residue after rinsing in Step 2 with concentrated hydrochloric acid with a concentration of 36wt% in a container. The mass ratio of filter residue to concentrated hydrochloric acid is 1:5. Then place the container on a heating plate and perform secondary heating and digestion at 230℃ for 10 minutes to obtain a secondary digestion solution with a volume of about 5mL.

[0349] Step 4: Filter the secondary digestion solution using the filter membrane from Step 2, and rinse the filter residue with 200 mL of water;

[0350] Step 5: Repeat steps 3 and 4 until the filtrate is a colorless and transparent solution, and obtain the product residue. Bake the product residue at 90°C for 10 hours, and then dry it in a desiccator for 1 hour.

[0351] Step Six: Weigh the container, product filter residue, and filter membrane to obtain the total weight m3. Based on the obtained m0, m1, m2, and m3, calculate the content Wt of the positive electrode active material in the positive electrode sheet according to the formula:

[0352] .

[0353] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0354] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0355] In some embodiments, the thickness of the positive electrode current collector is 10 μm-13 μm. For example, the thickness of the positive electrode current collector is 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, or any combination of two of these values. When the thickness of the positive electrode current collector is within the above range, the thickness of the current collector is relatively thin, which helps to increase the space occupied by the positive electrode active material layer, thereby increasing the volumetric energy density of the battery cell.

[0356] In the embodiments of this application, the thickness of the positive current collector has a meaning known in the art and can be detected using equipment and methods known in the art, such as performing a tomographic scan on the positive electrode sheet to directly measure the thickness of the positive current collector.

[0357] In some embodiments, the positive electrode active material may further include positive electrode active materials known in the art for use in batteries. As an example, the positive electrode active material may include lithium transition metal oxides and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNiO2). 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also known as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM523), LiNi 0.5 Co 0.25Mn 0.25 O2 (also known as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0358] It should be understood that, for the aforementioned positive electrode active materials, lithium-ion secondary batteries experience Li intercalation / deintercalation and consumption during charging and discharging. Therefore, the molar content of Li in the positive electrode active material varies depending on the discharge state of the lithium-ion secondary battery. In the examples of positive electrode active materials in this application, the molar content of Li refers to the initial state of the material, i.e., the state before feeding. After charge-discharge cycles, the molar content of Li changes when the positive electrode active material is applied to the battery system. Similarly, in the examples of positive electrode active materials in this application, the molar content of O is only an ideal value. Lattice oxygen release causes changes in the molar content of O, and the actual molar content of O will fluctuate.

[0359] In some embodiments, the positive electrode film layer further includes a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0360] In one embodiment, the positive electrode film layer further includes a conductive agent. As an example, the conductive agent may also include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, graphene, and carbon nanofibers.

[0361] In some embodiments, the positive electrode sheet can be prepared by forming a positive electrode slurry from the components described above. For example, the positive electrode active material, conductive agent, binder, and any other components are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry. The positive electrode slurry is then coated onto a positive electrode current collector, and after drying, cold pressing, and other processes, the positive electrode sheet is obtained.

[0362] Electrolyte

[0363] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not specify any particular type of electrolyte; it can be selected according to requirements. The electrolyte includes electrolyte salts and solvents.

[0364] In one embodiment, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0365] In one embodiment, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0366] In one embodiment, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0367] [Isolation membrane]

[0368] This application does not impose any particular restrictions on the type of separator membrane. For example, any well-known porous separator membrane with good chemical and mechanical stability can be selected.

[0369] In some embodiments, the coating includes heat-resistant particles. The heat-resistant particles may include at least one of inorganic particles and organic particles.

[0370] In some embodiments, inorganic particles may include one or more of the following: inorganic particles having a dielectric constant of 5 or greater, inorganic particles having ion conductivity but not storing ions, or inorganic particles capable of undergoing electrochemical reactions.

[0371] In some embodiments, inorganic particles having a dielectric constant of 5 or higher may include boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon oxides, tin dioxide, titanium oxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, hafnium dioxide, cerium oxide, zirconium titanate, barium titanate, magnesium fluoride, aluminum hydroxide, barium oxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, calcium fluoride, barium fluoride, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, bentonite, hydropyrite, Pb(Zr,Ti)O3 (abbreviated as PZT), Pb1-mLamZr1-nTinO3 (abbreviated as PLZT, 0 < m < 1, 0 < n < 1), Pb(Mg3Nb) 2 / 3The inorganic particles can be selected from one or more of PbTiO3 (PMN-PT) and their respective modified inorganic particles. Optionally, the modification of each inorganic particle can be chemical modification and / or physical modification.

[0372] In some embodiments, inorganic particles that are ion-conductive but do not store ions may include Li3PO4, lithium titanium phosphate (Li3PO4), etc. x3 Ti y3 (PO4)3, Lithium aluminum titanium phosphate (Li) x4 Al y4 Ti z4 (PO4)3、(LiAlTiP) x5 O y5 Type glass, lithium lanthanum titanate (Li) x6 La y6 TiO3, lithium germanium thiophosphate (Li) x7 Ge y7 P z7 S e Lithium nitride (Li) x8 N y8 SiS2 type glass Li x9 Si y9 S z9 and P2S5 type glass Li x10 P y10 S z10 One or more of the following are given: 0 < x3 < 2, 0 < y3 < 3, 0 < x4 < 2, 0 < y4 < 1, 0 < z4 < 3, 0 < x5 < 4, 0 < y5 < 13, 0 < x6 < 2, 0 < y6 < 3, 0 < x7 < 4, 0 < y7 < 1, 0 < z7 < 1, 0 < e < 5, 0 < x8 < 4, 0 < y8 < 2, 0 < x9 < 3, 0 < y9 < 2, 0 < z9 < 4, 0 < x10 < 3, 0 < y10 < 3, 0 < z10 < 7. This can improve the ion conductivity of the separator.

[0373] In some embodiments, the inorganic particles capable of undergoing electrochemical reactions may include one or more of lithium transition metal oxides, lithium transition metal phosphates, carbon-based materials, silicon-based materials, tin-based materials, and lithium titanium compounds.

[0374] In some embodiments, the organic particles may include at least one of a thermoplastic resin polymer, a thermosetting resin polymer, or a crosslinked polymer.

[0375] In some embodiments, the thermoplastic resin polymer may include one or more of the following: polycarbonate organic particles, polymethyl methacrylate organic particles, polyoxymethylene organic particles, polyamide organic particles, styrene-acrylonitrile copolymer, polyphenylene sulfide organic particles, polyether ether ketone organic particles, polyimide organic particles, polysulfone organic particles, polyether sulfone organic particles, polyphenylene sulfone organic particles, polybenzimidazole organic particles, polyamide-imide organic particles, and polyethyleneimine organic particles.

[0376] In some embodiments, the thermosetting resin polymer may include one or more of the following: phenolic resin organic particles, polymer particles containing triazine ring structural units, epoxy resin organic particles, unsaturated polyester resin organic particles, urea-formaldehyde resin organic particles, and furan resin organic particles.

[0377] In some embodiments, the crosslinking polymer may include one or more of crosslinked styrene organic particles and silicon-containing organic crosslinked resin particles.

[0378] In some embodiments, the coating includes adhesive particles. The adhesive particles may include homopolymers or copolymers of acrylate monomer units, homopolymers or copolymers of acrylic monomer units, homopolymers or copolymers of styrene monomer units, polyurethane compounds, rubber compounds, homopolymers or copolymers of fluorinated alkenyl monomer units, homopolymers or copolymers of olefinic monomer units, homopolymers or copolymers of unsaturated nitrile monomer units, homopolymers or copolymers of epoxide monomer units, and one or more of the modified compounds of the above homopolymers or copolymers.

[0379] In some embodiments, the adhesive particles may include copolymers of acrylate monomer units and styrene monomer units, copolymers of acrylate monomer units and styrene monomer units, copolymers of acrylate monomer units, acrylate monomer units, and styrene monomer units, copolymers of styrene monomer units and unsaturated nitrile monomer units, copolymers of styrene monomer units, olefin monomer units, and unsaturated nitrile monomer units, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylonitrile, polyethylene oxide, copolymers of different fluorinated alkenyl monomer units, copolymers of fluorinated alkenyl monomer units and vinyl monomer units, copolymers of fluorinated alkenyl monomer units and acrylate monomer units, copolymers of fluorinated alkenyl monomer units and acrylate monomer units, and one or more of the modified compounds of the above homopolymers or copolymers.

[0380] In some embodiments, the adhesive particles may include one or more of the following: butyl acrylate-styrene copolymer, butyl methacrylate-isooctyl methacrylate copolymer, isooctyl methacrylate-styrene copolymer, methacrylate-methacrylate-styrene copolymer, methyl acrylate-isooctyl methacrylate-styrene copolymer, butyl acrylate-isooctyl methacrylate-styrene copolymer, butyl acrylate-isooctyl methacrylate-styrene copolymer, butyl methacrylate-isooctyl methacrylate-styrene copolymer, butyl methacrylate-isooctyl methacrylate-styrene copolymer, styrene-acrylonitrile copolymer, styrene-butadiene-acrylonitrile copolymer, methyl acrylate-styrene-acrylonitrile copolymer, isooctyl methacrylate-styrene-acrylonitrile copolymer, styrene-vinyl acetate copolymer, styrene-vinyl acetate-pyrrolidone copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene-acrylic acid copolymer, vinylidene fluoride-hexafluoropropylene-acrylate copolymer, and a modified compound of the above copolymers.

[0381] In some embodiments, the coating may further include a dispersant, such as one or more of alkylphenol polyoxyethylene ethers, polyacrylic acid dispersants, and cellulose dispersants, including but not limited to. For example, the dispersant may include one or more of sodium carboxymethyl cellulose, sodium polyacrylate, and ammonium polyacrylate.

[0382] [Battery Device]

[0383] This application provides a battery device including the battery cells described in the above embodiments. The battery device can be a single physical module comprising one or more battery cells to provide higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, parallel, or mixed via a busbar.

[0384] In some embodiments, the battery device may be a battery pack, and the battery includes a housing and individual battery cells, with the individual battery cells or battery modules housed in the housing.

[0385] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0386] In some embodiments, the battery device may be located within an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0387] Figure 14 This is a schematic diagram of a battery device according to this application. Figure 14As shown, the battery device 20 may include multiple battery cells 10 to meet different power usage needs.

[0388] The battery device 20 may further include a housing with a hollow interior, housing multiple battery cells 10. For example, multiple battery cells 10 may be connected in parallel, series, or a combination thereof and then placed inside the housing. The housing may include a first housing portion 201 and a second housing portion 202, which are closed to each other to form the housing. The shapes of the first housing portion 201 and the second housing portion 202 may be determined based on the shape of the components housed inside, for example, based on the shape of the combination of multiple battery cells 10 housed inside. At least one of the first housing portion 201 and the second housing portion 202 may have an opening. For example, as... Figure 14 As shown, only one of the first housing portion 201 and the second housing portion 202 can be a hollow cuboid with an opening, while the other is plate-shaped to cover the opening. Taking the second housing portion 202 as a hollow cuboid with one opening, and the first housing portion 201 as a plate-shaped example, then the first housing portion 201 covers the opening of the second housing portion 202 to form a housing with a closed chamber, which can be used to accommodate multiple battery cells 10.

[0389] For example, unlike Figure 14 As shown, the first housing portion 201 and the second housing portion 202 can both be hollow cuboids with one open side each. The openings of the first housing portion 201 and the second housing portion 202 are opposite to each other, and the first housing portion 201 and the second housing portion 202 are interlocked to form a housing with a closed chamber, which can be used to accommodate multiple battery cells 10. The multiple battery cells 10 are connected in parallel, series, or mixed and placed in the housing formed by the interlocking of the first housing portion 201 and the second housing portion 202.

[0390] In some embodiments, the battery device 20 may further include other components. For example, the battery device 20 may further include a busbar component, which can be used to realize electrical connections between multiple battery cells 10, such as in parallel, series, or mixed connections. Specifically, the busbar component can realize electrical connections between battery cells 10 by connecting to the electrode terminals of the battery cells 10; or, the busbar component can also realize electrical connections between battery cells 10 by connecting to other components of the battery cells 10. The busbar component can be fixed to corresponding components of the battery cells 10 by welding, for example, by welding to electrode terminals, sealing structures, or housings, etc., and the embodiments of this application are not limited thereto.

[0391] The battery cells 10 can be directly assembled into the battery device 20, or they can be first assembled into battery modules, and then multiple battery modules can be assembled into the battery device 20.

[0392] [Electrical Equipment]

[0393] This application also provides an electrical device that includes the battery cell 10 in the foregoing embodiments.

[0394] Electrical equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical equipment.

[0395] like Figure 15 As shown, this application provides an electrical device, which is a vehicle.

[0396] Vehicle 30 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A motor, a controller, and battery cells 10 can be installed inside vehicle 30. The controller is used to control the battery cells 10 to supply power to the motor. For example, battery cells 10 can be located at the bottom, front, or rear of vehicle 30. Battery cells 10 can be used to power vehicle 30; for example, battery cells 10 can serve as the operating power source for vehicle 30's electrical system, such as meeting the power requirements for starting, navigation, and operation of vehicle 30. In another embodiment of this application, battery cells 10 can not only serve as the operating power source for vehicle 30 but also as the driving power source for vehicle 30, replacing or partially replacing gasoline or natural gas to provide driving power to vehicle 30.

[0397] [Examples and Comparative Examples]

[0398] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0399] Example 1

[0400] (1) Preparation of negative electrode sheet

[0401] The negative electrode sheet includes a negative current collector, a negative electrode undercoating layer on the negative current collector, and a negative electrode film layer. The negative electrode film layer is disposed on both sides of the negative current collector, and the negative electrode undercoating layer is located between the negative current collector and the negative electrode film layer. The negative current collector is a copper foil with a thickness of 5μm.

[0402] The negative electrode conductive undercoat on the negative electrode current collector is a film layer formed by uniformly mixing the second conductive agent superconducting carbon, the second binder styrene-butadiene rubber SBR, the thickener sodium carboxymethyl cellulose CMC-Na, and the solvent water, and then coating it on the surface of the negative electrode current collector and drying it. The thickness is 1 μm. The mass fraction of the second conductive agent in the negative electrode undercoat is 35 wt%, the mass fraction of the second binder in the negative electrode undercoat is 60 wt%, and the mass fraction of the thickener in the negative electrode undercoat is 5 wt%.

[0403] The negative electrode film layer comprises graphite particles in a mass ratio of 96:1:2:1, conductive agent acetylene black, binder styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose. The Dv50 of the graphite particles is 11.3 μm. The graphite particles include graphite bulk particles and a negative electrode coating layer covering the surface of the graphite bulk particles. The graphite bulk particles include secondary particles, and the negative electrode coating layer includes carbon elements. The mass content of carbon elements in the graphite particles is 2.5 wt%. The graphite bulk particles are artificial graphite.

[0404] The single-sided coating weight of the negative electrode film is 0.158g / 1540.25mm. 2 .

[0405] (2) Preparation of positive electrode sheet

[0406] The positive electrode includes a positive current collector, a positive electrode film layer, and a positive electrode undercoat layer. The positive electrode film layer is disposed on both sides of the positive current collector, and the positive electrode undercoat layer is located between the positive current collector and the positive electrode film layer. The positive current collector is a 13μm aluminum foil.

[0407] The positive electrode undercoating layer on the positive electrode current collector is a film layer formed by uniformly mixing the first conductive agent superconducting carbon, the first binder polyvinylidene fluoride PVDF, and the solvent N-methylpyrrolidone NMP, and then coating it on the surface of the positive electrode current collector and drying it. The thickness is 1μm. The mass fraction of the first conductive agent in the positive electrode undercoating layer is 43wt%, the mass fraction of the first binder is 55wt%, and the mass fraction of calcium hydroxide is 2wt%.

[0408] The positive electrode film layer comprises a film layer formed by uniformly coating a positive electrode slurry (solvent being N-methylpyrrolidone NMP) onto the surface of a positive electrode undercoating layer, followed by drying and cold pressing. The positive electrode film layer comprises positive electrode active material, binder polyvinylidene fluoride PVDF, and conductive agent acetylene black in a weight ratio of 97:2:1.

[0409] The positive electrode active material includes lithium iron phosphate particles and a positive electrode coating layer. The positive electrode coating layer is coated on the surface of the lithium iron phosphate particles. The positive electrode coating layer includes lithium titanium iron phosphate (Li2FeTi(PO4)3) and carbon. The mass fraction of carbon in the positive electrode active material is 1.12 wt%.

[0410] The single-sided coating weight of the positive electrode film is 0.365g / 1540.25mm. 2 .

[0411] The positive electrode includes a positive electrode body and a positive electrode tab. The positive electrode body includes a positive electrode film and a first transition region. The first transition region includes insulating material PVDF, and its dimension L7 is 2 mm along a first direction. The positive electrode tab includes a second transition region, which also includes insulating material PVDF. Its dimension L6 is 5 mm along the first direction.

[0412] (3) Separating membrane

[0413] The separator includes a base film, a first coating, and a second coating. The base film consists of 7μm polyethylene. The first coating is a film layer formed by applying alumina particles and a binder polyvinylidene fluoride to both sides of the base film, with a thickness of 2μm. The average particle size of the alumina particles is 100nm-1000nm. The second coating is a film layer formed by applying polyvinylidene fluoride to the first coating, with a thickness of 1μm.

[0414] (4) Preparation of electrolyte

[0415] The electrolyte consists of organic solvents, lithium electrolyte salts, and additives.

[0416] The components of each organic solvent are mixed, and then an electrolyte lithium salt and additives are added to prepare an electrolyte.

[0417] The organic solvents include 28 wt% dimethyl carbonate (DMC), 33 wt% EMC, and 20 wt% ethylene carbonate (EC). The mass percentage of each component in the solvent is calculated based on the total mass of the electrolyte.

[0418] Based on the total mass of the electrolyte, the electrolyte also includes 2 wt% vinylene carbonate (VC) and 1 wt% fluoroethylene carbonate (FEC).

[0419] The electrolyte lithium salt comprises lithium bis(fluorosulfonyl)imide (LiFSI) at a mass content of 10 wt% and lithium hexafluorophosphate (LiPF6) at a mass fraction of 6 wt%.

[0420] (5) Preparation of battery cells

[0421] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes to obtain an electrode assembly. The electrode assembly is then placed in a housing, with the positive and negative terminals set on the housing. After baking, electrolyte is injected (multiple injections can be performed if necessary). After vacuum sealing, settling, formation, and shaping, a battery cell is obtained.

[0422] The compaction density of the positive electrode sheet of a single battery cell at 0% SOC is 2.5 / cm². 3 The compaction density of the negative electrode sheet is 1.46 g / cm³. 3 .

[0423] The thickness of the first wall of the battery cell casing is 1.2 mm, and the thickness of the other walls of the casing is 0.5 mm.

[0424] In Examples 1-1 to 1-2 and Comparative Examples 1-1 to 1-2, the dimensions of the first transition zone along the first direction and the arrangement of the battery cells with respect to the insulating support are different, as detailed in Table 1.

[0425] In Examples 2-1 to 2-4 and Comparative Example 2-1, the dimensions of the first transition zone along the first direction, the ratio of the dimensions of the first transition zone along the first direction to the dimensions of the main body along the first direction, and the dimensions of the second transition zone along the first direction are different, as detailed in Table 2.

[0426] In Examples 3-1 to 3-4, the lithium salt in the electrolyte is set in different ways, as detailed in Table 3.

[0427] 1. VED test of individual battery cells

[0428] At 25℃, the battery cell is charged at a constant current of 0.33C to 3.65V, then at a constant voltage of 0.05C, and then discharged at 0.33C to 2.5V. This cycle is repeated 3 times. The discharge energy of the last cycle is recorded as W. The length, width, and height of the battery cell casing are measured, and the volume V of the battery cell is calculated. The volumetric energy density of the battery cell is VED = W / V.

[0429] 2. Safety performance (short circuit probability) test of individual battery cells

[0430] At 25℃, individual battery cells were charged at a constant current of 0.33C to 3.65V, then charged at a constant voltage to 0.05C (100% SOC). Ten battery cells charged to 100% SOC were then stored at 60℃ for one year. During storage, the capacity retention rate of each battery cell was tested monthly, and the average monthly capacity retention rate was monitored. The number of battery cells with abnormal capacity retention during storage was observed and recorded. Short circuit probability = number of battery cells with abnormal capacity retention during storage / 10.

[0431] The capacity retention rate of a single battery cell is calculated as follows: the first discharge capacity of the battery cell in the current month / the first discharge capacity of the battery cell in the previous month. The discharge conditions are 0.33C to 2.5V.

[0432] The average monthly capacity retention rate of a single battery cell is the sum of the capacity retention rates of the 10 tested battery cells for that month, divided by 10.

[0433] The criteria for determining abnormal capacity retention rate are: the capacity retention rate of the battery cell is 5% or more lower than the average capacity retention rate of the month.

[0434] 3. Internal resistance test of individual battery cells

[0435] At 25℃, the battery cell is charged at a constant current of 0.5C to 3.65V, and then charged at a constant voltage until the current is 0.05C. The battery cell is then discharged at a constant current of 0.5C for 30 minutes to adjust the battery cell to 50% SOC. The voltage of the battery cell at this time is recorded as U1. The battery cell is then discharged at a constant current of 4C for 30 seconds, and the voltage at the end of the discharge is recorded as U2, using a sampling time of 0.1 seconds. The initial DCR of the battery cell is represented by the discharge DCR at 50% SOC. The initial DCR of the battery cell is calculated as (U1-U2) / 4C.

[0436] Table 1: Product parameters and performance data of Examples 1-1 to 1-2 and Comparative Examples 1-1 to 1-2

[0437]

[0438] In Table 1, "L7" indicates the dimension of the first transition zone along the first direction. "Whether it is provided" indicates whether an insulating support is provided between the positive terminal cap assembly and the positive terminal tab. "VED" indicates the volumetric energy density measured in the energy density test of the battery cell. "Short circuit probability" indicates the short circuit probability measured in the safety performance test of the battery cell.

[0439] The comparative analysis of the data in Table 1 shows that by adding an insulating support to the positive electrode, the positive electrode tab can be effectively prevented from being inserted backwards into the main body, thus improving the safety performance of the battery cell. Simultaneously, by setting a first transition zone, the safety performance of the battery cell can be further improved. Therefore, through the design of the first transition zone and the insulating support, the battery cell can achieve both high energy density and safety performance.

[0440] Table 2: Product parameters and performance data of Examples 2-1 to 2-4 and Comparative Example 2-1

[0441]

[0442] In Table 2, "L7" represents the dimension of the first transition region along the first direction. "L6" represents the dimension of the second transition region along the first direction. "L7 / L1" represents the ratio of the dimension of the first transition region along the first direction to the dimension of the positive electrode body along the first direction.

[0443] Analysis of the data in Table 2 shows that controlling the size of the first transition region within the range of 0mm-2mm is more conducive to achieving a balance between energy density and safety performance in the battery cell. Furthermore, controlling the ratio of the size of the first transition region to the size of the positive electrode body in the first direction within the range of 0.4%-1.3% is also more conducive to achieving a balance between energy density and safety performance in the battery cell.

[0444] In Table 2, the dimensions of the second transition zone along the first direction are all within the range of 3mm-6mm. While helping to improve the safety performance of the battery cell, it also provides sufficient space for welding the positive electrode tab, which is beneficial for the assembly of the battery cell.

[0445] Table 3: Product parameters and performance data of Examples 3-1 to 3-4

[0446]

[0447] In Table 3, "LiFSI" represents the mass fraction of lithium bis(fluorosulfonyl)imide in the electrolyte. "LiPF6" represents the mass fraction of lithium hexafluorophosphate in the electrolyte. The VED of the battery cells in Table 3 is 445 Wh / L.

[0448] According to the data in Table 3, using a two-component lithium salt and controlling the mass fraction of LiFSI in the electrolyte to be greater than the mass fraction of LiPF6 is more conducive to ensuring both safety and rate performance of the battery cell.

[0449] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, The battery cell includes: The housing includes a casing, a positive terminal cover assembly, and a negative terminal cover assembly. The casing has two openings that are arranged opposite each other along a first direction, which is the extension direction of the longest side of the battery cell. The positive terminal cover assembly and the negative terminal cover assembly are respectively covered by the openings. An electrode assembly includes a plurality of stacked electrode plates, the electrode assembly including an electrode tab and a main body, the electrode tab extending from the main body along a first direction; The electrode sheet includes a positive electrode sheet, which includes a positive current collector and a positive electrode film layer disposed on at least one side surface of the positive current collector. The positive electrode film layer includes a positive active material. The positive electrode sheet includes a positive electrode body portion and a positive electrode tab, which extends from the positive electrode body portion along the first direction. An insulating support is provided between the positive terminal cap assembly and the positive terminal tab. The insulating support includes a through hole through which the positive terminal tab passes to connect with the positive terminal cap assembly. The insulating support is provided with a channel structure for allowing electrolyte to pass through the insulating support. The positive electrode body includes the positive electrode film layer and a first transition region. Along the first direction, the first transition region is located at one end of the positive electrode film layer near the positive electrode tab. The first transition region includes an insulating material. Along the first direction, the size of the first transition region is 0 mm to 2 mm.

2. The battery cell according to claim 1, characterized in that, Along the first direction, the ratio of the size of the first transition region to the size of the positive electrode body is 0.4% to 1.3%.

3. The battery cell according to claim 1, characterized in that, The positive electrode tab includes a second transition region. Along the first direction, the second transition region is located at one end of the positive electrode tab near the positive electrode body. The second transition region is provided with insulating material.

4. The battery cell according to claim 3, characterized in that, Along the first direction, the size of the second transition region is 3mm to 6mm.

5. The battery cell according to claim 3 or 4, characterized in that, Along the first direction, the ratio of the size of the second transition region to the size of the positive electrode tab is 1 / 8 to 1 / 3.

6. The battery cell according to claim 1, characterized in that, The electrode sheet includes a negative electrode sheet, the negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one side surface of the negative current collector, the negative electrode film layer includes a negative electrode active material; Along the first direction, the edge of the negative electrode film extends beyond the edge of the positive electrode film.

7. The battery cell according to claim 1, characterized in that, When the size of the first transition region is 0 mm, the positive electrode body includes an empty foil region, which is located at the end of the positive electrode film layer near the positive electrode tab along the first direction.

8. The battery cell according to claim 1, characterized in that, The insulating material includes at least one of alumina, boehmite, magnesium oxide, polyacrylate, and polyvinylidene fluoride.

9. The battery cell according to claim 1, characterized in that, The insulating material includes an adhesive, which includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, and vinylidene fluoride-trifluorochloroethylene copolymer.

10. The battery cell according to claim 1, characterized in that, The positive electrode sheet has a dimension of 225 mm to 240 mm along the first direction; The positive electrode sheet has a dimension of 80 mm to 120 mm along the second direction; The second direction is the height direction of the battery cell, and the second direction is perpendicular to the first direction.

11. The battery cell according to claim 1, characterized in that, The electrode plates include a negative electrode plate. The negative electrode sheet has a dimension of 227 mm to 245 mm along the first direction; The negative electrode sheet has a dimension of 80mm to 120mm along the second direction, which is the height direction of the battery cell and is perpendicular to the first direction.

12. The battery cell according to claim 1, characterized in that, The insulating support includes two oppositely arranged bosses, which are connected by two beams. The two bosses and the two beams together form the through hole.

13. The battery cell according to claim 12, characterized in that, In the thickness direction of the insulating support, the size of the boss is larger than the size of the beam.

14. The battery cell according to claim 12 or 13, characterized in that, Along the first direction, the size of the boss is 5.0 mm to 9.0 mm; the size of the beam is 3.0 mm to 9.0 mm.

15. The battery cell according to claim 12, characterized in that, The boss is provided with the channel structure.

16. The battery cell according to claim 1, characterized in that, The ratio of the maximum dimension of the positive electrode tab along the second direction to the dimension of the positive electrode sheet along the second direction is 1 / 4 to 1 / 2, where the second direction is the height direction of the battery cell and is perpendicular to the first direction.

17. The battery cell according to claim 1, characterized in that, The positive terminal cap assembly includes a first cap body, the first cap body including at least one tab lead-out hole for the positive terminal tab to pass through the tab lead-out hole and be electrically connected to the first cap body.

18. The battery cell according to claim 17, characterized in that, The battery cell includes a metal sheet, and the positive electrode tab is welded to the metal sheet. The metal sheet is used to pass through the lead-out hole of the electrode tab and is welded to the first cover body so that the positive electrode tab is electrically connected to the first cover body.

19. The battery cell according to claim 18, characterized in that, The thickness of the metal sheet is 0.15 mm to 0.4 mm.

20. The battery cell according to any one of claims 17-19, characterized in that, The first cover includes a first positive electrode outlet hole and a second positive electrode outlet hole arranged parallel to a third direction. The third direction is the width direction of the battery cell, which is perpendicular to the first direction and perpendicular to the second direction. The second direction is the height direction of the battery cell, which is perpendicular to the first direction. The plurality of positive electrode plates of the electrode assembly are stacked along the third direction; The electrode assembly includes a first electrode assembly and a second electrode assembly, wherein the first electrode assembly includes a first positive electrode tab and the second electrode assembly includes a second positive electrode tab; The first positive electrode tab extends out of the first positive electrode through-hole, and the second positive electrode tab extends out of the second positive electrode through-hole.

21. The battery cell according to claim 18, characterized in that, The first cover has a first flat portion and a first recess recessed into the battery cell along the first direction, the first recess being configured to accommodate at least a portion of the positive electrode tab or the metal sheet passing through the tab lead-out hole.

22. The battery cell according to claim 21, characterized in that, The first recess has a first surface and a second surface along the first direction, the first surface being the surface facing away from the electrode assembly, and the second surface being the surface facing the electrode assembly. At least a portion of the positive electrode tab is welded to the first surface, or at least a portion of the metal sheet is welded to the first surface.

23. The battery cell according to claim 1, characterized in that, The casing is positively charged.

24. The battery cell according to claim 21, characterized in that, The first straight portion has a third surface and a fourth surface along the first direction, the third surface being located inside the battery cell and the fourth surface being located outside the battery cell; Along the first direction, the distance between the main body and the third surface is 8.0 mm to 13.0 mm.

25. The battery cell according to claim 24, characterized in that, The positive end cap assembly includes a second cap body, wherein the first cap body is welded to the second cap body; The second cover has a second flat portion and a first protrusion protruding outward from the battery cell along the first direction. The first protrusion is disposed opposite to the third surface and is configured to accommodate at least a portion of the positive electrode tab or the metal sheet passing through the tab lead-out hole.

26. The battery cell according to claim 25, characterized in that, The first cover also has a second recess recessed into the battery cell along the first direction, the second recess being used to accommodate the second straight portion so that the first cover is welded to the second cover.

27. The battery cell according to claim 1, characterized in that, The negative terminal cap assembly includes a negative terminal, and the negative terminal includes a negative terminal post; The electrode plate includes a negative electrode plate, the negative electrode plate includes a negative electrode tab, the negative electrode tab extends from the negative electrode plate along the first direction and is welded to the negative electrode post; or... The negative electrode tab extends from the negative electrode sheet along the first direction and is welded to the negative electrode post through a busbar component.

28. The battery cell according to claim 27, characterized in that, The negative terminal cap assembly includes a third cap, the third cap includes an electrode lead-out hole, and the negative terminal post passes through the electrode lead-out hole; The negative terminal cover assembly includes a first insulating member disposed between the negative terminal and the third cover body for insulating the negative terminal and the third cover body.

29. The battery cell according to claim 28, characterized in that, The first insulating member includes a third straight portion and a third recess disposed on one side facing the main body portion; the third recess is configured to accommodate at least a portion of the negative electrode tab.

30. The battery cell according to claim 29, characterized in that, The dimension of the third straight portion along the first direction is 4.5 mm to 8.0 mm.

31. The battery cell according to claim 28, characterized in that, The negative terminal includes the negative electrode post and a limiting part, the negative electrode post passing through the electrode lead-out hole, and the limiting part being connected to the negative electrode post; Along the first direction, the limiting portion is located on the side of the third cover facing the electrode assembly, and the limiting portion is configured to restrict the negative electrode post from disengaging from the electrode lead-out hole in a direction away from the electrode assembly.

32. The battery cell according to claim 27, characterized in that, The busbar component has a sheet-like structure and a thickness of 0.6 mm to 1.2 mm.

33. The battery cell according to claim 1, characterized in that, A first insulating film is provided between the main body and the housing, and the first insulating film is used to insulate the main body and the housing.

34. The battery cell according to claim 33, characterized in that, The electrode plate includes a negative electrode plate, the negative electrode plate includes a negative electrode tab, a second insulating film is disposed between the negative electrode tab and the first insulating film, the second insulating film covers the negative electrode tab and extends to the space between the main body and the shell; The second insulating film is used to insulate the negative electrode tab and the housing.

35. The battery cell according to claim 1, characterized in that, The areal density of the positive electrode sheet is 0.33 g / 1540.25 mm. 2 Up to 0.40g / 1540.25mm 2 .

36. The battery cell according to claim 1, characterized in that, When the battery cell has a state of 0% SOC, the compaction density of the positive electrode sheet is 2.4 g / cm³. 3 Up to 2.7 g / cm 3 .

37. The battery cell according to claim 1, characterized in that, The thickness of the positive current collector is 12 μm to 15 μm.

38. The battery cell according to claim 1, characterized in that, The ratio of the thickness of the positive current collector to the total thickness of the positive electrode sheet is 4.5% to 7%.

39. The battery cell according to claim 1, characterized in that, The electrode sheet includes a negative electrode sheet, and the areal density of the negative electrode sheet on one side is 0.130 g / 1540.25 mm. 2 Up to 0.175g / 1540.25mm 2 .

40. The battery cell according to claim 1, characterized in that, The electrode sheet includes a negative electrode sheet. When the battery cell has a state of 0% SOC, the compaction density of the negative electrode sheet is 1.37 g / cm³. 3 Up to 1.55 g / cm 3 .

41. The battery cell according to claim 1, characterized in that, The electrode sheet includes a negative electrode sheet, which includes a negative current collector and a negative electrode film layer disposed on at least one side surface of the negative current collector. The negative electrode film layer includes a negative electrode active material. The thickness of the negative current collector is 4 μm to 7 μm.

42. The battery cell according to claim 1, characterized in that, The electrode sheet includes a negative electrode sheet, which includes a negative current collector and a negative electrode film layer disposed on at least one side surface of the negative current collector. The negative electrode film layer includes a negative electrode active material. The ratio of the thickness of the negative current collector to the total thickness of the negative electrode sheet is 2% to 6%.

43. The battery cell according to claim 1, characterized in that, The electrode sheet includes a negative electrode sheet, and a separator is disposed between the positive electrode sheet and the negative electrode sheet. The separator includes a base film and a coating disposed on at least one side of the base film. The coating includes inorganic particles.

44. The battery cell according to claim 43, characterized in that, The thickness of the base film is 5 μm to 9 μm.

45. The battery cell according to claim 43 or 44, characterized in that, The coating thickness is 1 μm to 5 μm.

46. ​​The battery cell according to claim 1, characterized in that, The positive electrode active material includes one or more of lithium transition metal oxides and lithium transition metal phosphates.

47. The battery cell according to claim 1, characterized in that, The battery cell includes an electrolyte, which includes a lithium salt, and the lithium salt includes one or more of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate.

48. The battery cell according to claim 47, characterized in that, The electrolyte comprises lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, and the mass fraction of lithium bis(fluorosulfonyl)imide is greater than or equal to the mass fraction of lithium hexafluorophosphate based on the total mass of the electrolyte.

49. The battery cell according to claim 47, characterized in that, The mass fraction of the lithium difluorosulfonamide is 5 wt% to 12 wt% based on the total mass of the electrolyte.

50. The battery cell according to claim 47, characterized in that, The mass fraction of the lithium bis(fluorosulfonyl)imide is 8 wt% to 12 wt% based on the total mass of the electrolyte.

51. The battery cell according to claim 47, characterized in that, The lithium hexafluorophosphate has a mass fraction of 4.5 wt% to 8 wt% based on the total mass of the electrolyte.

52. The battery cell according to claim 47, characterized in that, The lithium salt has a mass fraction of 15 wt% to 20 wt% based on the total mass of the electrolyte.

53. The battery cell according to claim 47, characterized in that, The electrolyte includes additives, which include one or more of vinylene carbonate and fluoroethylene carbonate.

54. The battery cell according to claim 53, characterized in that, The mass fraction of the vinylene carbonate is from 0.01 wt% to 5.00 wt% based on the total mass of the electrolyte.

55. The battery cell according to claim 53, characterized in that, The mass fraction of vinylene carbonate is 1 wt% to 2.5 wt% based on the total mass of the electrolyte.

56. The battery cell according to claim 53, characterized in that, The mass fraction of the fluoroethylene carbonate is 0.01 wt% to 4 wt% based on the total mass of the electrolyte.

57. The battery cell according to claim 53, characterized in that, The mass fraction of the fluoroethylene carbonate is 0.1 wt% to 0.5 wt% based on the total mass of the electrolyte.

58. The battery cell according to claim 47, characterized in that, The electrolyte has an ionic conductivity of 9.0 mS / cm to 13 mS / cm at room temperature.

59. The battery cell according to claim 47, characterized in that, The electrolyte includes cyclic carbonate solvents, including ethylene carbonate.

60. The battery cell according to claim 59, characterized in that, The mass fraction of the cyclic carbonate solvent is 15 wt% to 30 wt% based on the total mass of the electrolyte.

61. The battery cell according to claim 47, characterized in that, The electrolyte includes linear carbonate solvents, including dimethyl carbonate.

62. The battery cell according to claim 61, characterized in that, The mass fraction of dimethyl carbonate is 20 wt% to 35 wt% based on the total mass of the electrolyte.

63. The battery cell according to claim 1, characterized in that, The dimensions of the battery cell along the first direction are 230 mm to 350 mm; The dimension of the battery cell along the second direction is 100mm to 130mm, the second direction is the height direction of the battery cell, and the second direction is perpendicular to the first direction; The dimensions of the battery cell along a third direction are 23mm to 50mm, the third direction being the width direction of the battery cell, and the third direction is perpendicular to the first direction and perpendicular to the second direction.

64. The battery cell according to claim 1, characterized in that, The battery cell includes a pressure relief mechanism disposed on the first wall of the housing, the first wall having a thickness of 1.2 mm to 1.5 mm.

65. A battery device, characterized in that, The battery device comprises the battery cell according to any one of claims 1-64.

66. An electrical appliance, characterized in that, The electrical equipment includes a battery cell as described in any one of claims 1-64, and / or a battery device as described in claim 65.

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