Battery cell, battery device and electrical equipment

Abstract

The present application discloses a battery cell, a battery device, and an electrical equipment. The battery cell includes a housing, the housing includes a first wall, and the housing has a receiving cavity; an electrode terminal disposed on the first wall, the minimum cross-sectional area of the electrode terminal being S; and an electrode assembly disposed in the receiving cavity, the electrode assembly including a positive electrode plate, the positive electrode plate including a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector, the positive electrode film layer including a lithium-containing phosphate. Wherein, the ratio of the volumetric energy density VED of the battery cell to S is: 2 Wh / L / mm<supgt;2< / supgt> to 10 Wh / L / mm<supgt;2< / supgt>. Thereby, heat generation of the electrode terminal can be reduced during the fast charging process, and a battery cell with excellent fast charging performance and cycle life can be obtained.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the priority of PCT patent application PCT / CN2025 / 071091 entitled "Battery Cell, Battery Device and Electrical Equipment" filed on January 7, 2025, the entire content of which is incorporated herein by reference. Technical Field

[0003] This application relates to the field of batteries, and more particularly, to battery cells, battery devices and electrical equipment. Background Art

[0004] Batteries are not only used in energy storage power systems such as hydro, thermal, wind and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles and electric cars, as well as in many fields such as military equipment and aerospace. When charging a battery at a high rate, the battery generates a large amount of heat, which will affect the long-term performance of the battery. Summary of the Invention

[0005] In a first aspect of the present application, there is provided a battery cell, the battery cell comprising a housing, the housing comprising a first wall, the housing having a receiving cavity; an electrode terminal disposed on the first wall, the minimum cross-sectional area of the electrode terminal being S; an electrode assembly disposed in the receiving cavity, the electrode assembly comprising a positive electrode tab, the positive electrode tab comprising a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector, the positive electrode film layer comprising a lithium-containing phosphate, wherein the ratio of the volumetric energy density VED of the battery cell to S is: 2 Wh / L / mm 2 to 10 Wh / L / mm 2 . Thus, by making the ratio of the volumetric energy density VED of the battery cell to S within the above range, when charging the battery cell at a high rate, the heat generation of the electrode terminal can be reduced, and a battery cell containing lithium phosphate with excellent fast charging performance and cycle life can be obtained.

[0006] According to some embodiments of the present application, the ratio of the volumetric energy density VED of the battery cell to S is 2 Wh / L / mm 2 to 3.5 Wh / L / mm 2 . Thus, the heat generation of the electrode terminal is further reduced, and a battery cell with excellent fast charging performance and cycle life can be obtained.

[0007] According to some embodiments of the present application, the volumetric energy density VED of the battery cell satisfies: 350 Wh / L ≤ VED ≤ 430 Wh / L. Thus, the capacity of the battery cell is increased.

[0008] According to some embodiments of the present application, the minimum cross-sectional area S of the electrode terminal satisfies: 40 mm 2 ≤S≤800mm 2 As a result, the current carrying capacity of the electrode terminal is improved, the resistance is reduced, and the heat generation of the electrode terminal is reduced.

[0009] According to some embodiments of the present application, the battery cell includes a cover plate assembly, the cover plate assembly forms the first wall, the cover plate assembly includes a cover plate and the electrode terminal, the cover plate is provided with a through hole, the electrode terminal includes a terminal body, a first limiting portion and a second limiting portion, the terminal body passes through the through hole and connects the first limiting portion and the second limiting portion, the first limiting portion is located on the side of the cover plate facing the accommodating cavity, and the second limiting portion is located on the side of the cover plate away from the accommodating cavity. Thus, the risk of the electrode terminal being separated from the through hole is reduced, the battery cell can normally input or output electrical energy, and the service life of the battery cell is increased.

[0010] According to some embodiments of the present application, the cross-sectional area of the second limiting portion is 300 mm 2 Up to 700mm 2 As a result, the current carrying capacity of the electrode terminal is improved and the heat generation of the electrode terminal is reduced.

[0011] According to some embodiments of the present application, the cross-sectional area of the first limiting portion is 200 mm 2 Up to 800mm 2 As a result, the current carrying capacity of the electrode terminal is improved and the heat generation of the electrode terminal is reduced.

[0012] According to some embodiments of the present application, the cross section of the terminal body is a rounded rectangle, thereby improving the current carrying capacity of the electrode terminal when the cover plate area is small.

[0013] According to some embodiments of the present application, the cross-sectional area of the terminal body is 40 mm 2 Up to 240mm 2 As a result, the current carrying capacity of the electrode terminal is improved and the heat generation of the electrode terminal is reduced.

[0014] According to some embodiments of the present application, the cap plate assembly is disposed at both ends of the housing, and each of the cap plate assemblies includes at least two electrode terminals, thereby reducing the resistance of the battery cell and improving the current carrying capacity of the battery cell.

[0015] According to some embodiments of the present application, the cap plate assembly is disposed at both ends of the housing, and each cap plate assembly includes at least two electrode terminals, and the two electrode terminals have opposite polarities, thereby shortening the current path and reducing the internal resistance of the battery cell.

[0016] According to some embodiments of the present application, the cover plate assemblies are arranged at both ends of the housing. Each cover plate assembly includes at least two electrode terminals, and the polarities of the two electrode terminals are opposite. In the length direction of the battery cell, the electrode terminals with the same polarity on the two cover plate assemblies are arranged in a staggered manner. Optionally, the electrode terminals with the same polarity are arranged diagonally in the length direction of the battery cell. Thus, during the battery assembly process, the wiring can be reduced and the assembly difficulty can be lowered.

[0017] According to some embodiments of the present application, the electrode assembly further includes a negative electrode plate. The positive electrode plate and the negative electrode plate are stacked, and a positive electrode tab is arranged on each positive electrode plate, and a negative electrode tab is arranged on each negative electrode plate. Thus, the current transmission efficiency is improved, the resistance of the battery cell is reduced, and the rate performance of the battery is improved.

[0018] According to some embodiments of the present application, the positive electrode tab extends along the length direction or the width direction of the positive electrode plate; and / or the negative electrode tab extends along the length direction or the width direction of the negative electrode plate. Thus, the current transmission efficiency is improved, the resistance of the battery cell is reduced, and the rate performance of the battery is improved.

[0019] According to some embodiments of the present application, along the length direction of the positive electrode plate, the coating length of the positive electrode film layer is 200 mm - 700 mm. Thus, the energy density of the battery cell is improved.

[0020] According to some embodiments of the present application, the compaction density of the positive electrode film layer corresponding to the battery cell at 100% SOC is 2.5 g / cm 3 - 2.8 g / cm 3 . Thus, the energy density of the battery cell is improved.

[0021] According to some embodiments of the present application, the single-sided coating weight of the positive electrode film layer is 200 mg / 1540.25 mm 2 - 340 mg / 1540.25 mm 2 , and optionally 240 mg / 1540.25 mm 2 - 300 mg / 1540.25 mm 2 . Thus, the energy density of the battery cell is improved.

[0022] According to some embodiments of the present application, the charging gram capacity of the lithium-containing phosphate at 0.1C rate is 150 mAh / g - 170 mAh / g. Thus, the energy density of the battery cell is improved.

[0023] According to some embodiments of the present application, the lithium-containing phosphate includes the compound shown in Formula I: Li x1A y1 Me a M b P 1-c X c Y z Formula I, wherein 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, and 0.9 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a ≤ 1.5, 0 ≤ b ≤ 0.5, and 0.9 ≤ a + b ≤ 1.5, 0 ≤ c ≤ 0.5, 3 ≤ z ≤ 5, A includes one or more of Na, K, and Mg, Me includes one or more of Mn, Fe, Co, and Ni, M includes one or more of B, Mg, Al, P, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce, X includes one or more of S, Si, Cl, B, C, and N, and Y includes one or two of O and F. Thereby, the safety performance and cycle life of the battery cell are improved.

[0024] According to some embodiments of the present application, the lithium-containing phosphate includes lithium iron phosphate material. Thereby, the safety performance and cycle life of the battery cell are improved.

[0025] According to some embodiments of the present application, the lithium-containing phosphate is granular, and the volume average particle size Dv50 of the lithium-containing phosphate is 1 µm - 2 µm. Thereby, the migration path of lithium ions in the solid phase is shortened, the polarization of the battery cell is reduced, and the heat generation of the battery cell is reduced.

[0026] According to some embodiments of the present application, the volume particle size Dv10 of the lithium-containing phosphate is 0.4 µm - 0.7 µm. Thereby, the migration path of lithium ions in the solid phase is shortened, the polarization of the battery cell is reduced, and the heat generation of the battery cell is reduced.

[0027] According to some embodiments of the present application, the lithium-containing phosphate includes secondary particles, and the average particle size of the primary particles in the secondary particles is 200 nm - 500 nm. Thereby, the migration path of lithium ions in the solid phase is shortened, the polarization of the battery cell is reduced, and the heat generation of the battery cell is reduced.

[0028] According to some embodiments of the present application, the positive electrode film layer further includes a lithium supplement agent, and based on the total mass of the positive electrode film layer, the mass ratio of the lithium supplement agent is 0.1% - 5%. Thereby, the lithium consumption during the formation of the solid electrolyte interface film (SEI film) on the negative electrode is compensated, and the initial efficiency of the battery is improved.

[0029] According to some embodiments of the present application, the lithium supplementing agent includes one or more of lithium nickel cobalt manganate, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganite, lithium tartrate, trilithium citrate, lithium nickelate, and lithium ferrate. Thereby, the lithium consumption during the formation of the SEI film on the negative electrode is compensated, and the initial efficiency of the battery is improved.

[0030] According to some embodiments of the present application, the positive electrode film layer further includes a conductive agent, and based on the total mass of the positive electrode film layer, the mass ratio of the conductive agent is 0.1% - 1%. Thereby, the electronic conductivity of the positive electrode film layer is improved.

[0031] According to some embodiments of the present application, the conductive agent includes carbon nanotubes. Thereby, the contact area between the conductive agent and the positive electrode active material is increased, and the electronic conductivity of the positive electrode film layer is improved.

[0032] According to some embodiments of the present application, the thickness of the positive electrode current collector is 10 µm - 16 µm. Thereby, the current-carrying capacity of the positive electrode current collector is improved, and the energy density of the battery cell is increased.

[0033] According to some embodiments of the present application, the electrode assembly further includes a negative electrode tab, the negative electrode tab includes a negative electrode current collector, and a negative electrode film layer is provided on at least one side of the negative electrode current collector. The compaction density of the negative electrode film layer corresponding to the battery cell at 100% SOC is 1.15 g / cm 3 -1.36 g / cm 3 , optionally 1.25 g / cm 3 -1.36 g / cm 3 . Thereby, the energy density of the battery cell is increased.

[0034] According to some embodiments of the present application, the electrode assembly further includes a negative electrode tab, the negative electrode tab includes a negative electrode current collector, and a negative electrode film layer is provided on at least one side of the negative electrode current collector. The single-sided coating weight of the negative electrode film layer is 90 mg / 1540.25 mm 2 -170 mg / 1540.25 mm 2 , optionally 110 mg / 1540.25 mm 2 -150 mg / 1540.25 mm 2 . Thereby, the energy density of the battery cell is increased.

[0035] According to some embodiments of the present application, the negative electrode film layer includes a negative electrode active material, and the charging gram capacity of the negative electrode active material at a 0.1C rate is 350 mAh / g - 480 mAh / g. Thereby, the energy density of the battery cell is increased.

[0036] According to some embodiments of the present application, the negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer. The first negative electrode is disposed on at least one side of the negative electrode current collector, and the second negative electrode film layer is disposed on a side of the first negative electrode film layer facing away from the negative electrode current collector. The first negative electrode film layer includes first graphite particles, and the second negative electrode film layer includes second graphite particles. The volume average particle size of the first graphite particles is greater than the volume average particle size of the second graphite particles. Thus, the volume average particle size of the second graphite particles is smaller, which can shorten the solid-phase transmission path of lithium ions and improve the fast charging performance of the battery cell.

[0037] According to some embodiments of the present application, the first graphite particles include natural graphite. Thus, the compaction density of the negative electrode sheet is increased.

[0038] According to some embodiments of the present application, the volume average particle size Dv50 of the first graphite particles is 7 µm - 18.5 µm; and / or the volume average particle size Dv50 of the second graphite particles is 7 µm - 14.3 µm. Thus, the volume average particle size of the second graphite particles is smaller, which can shorten the solid-phase transmission path of lithium ions and improve the fast charging performance of the battery cell.

[0039] According to some embodiments of the present application, the first negative electrode film layer and / or the second negative electrode film layer includes a silicon-based material. Based on the total mass of the negative electrode film layer, the mass percentage of silicon element is 0.3% - 10%. Thus, the capacity of the negative electrode active material is increased, and the energy density of the battery cell is improved.

[0040] According to some embodiments of the present application, the thickness of the negative electrode current collector is 4 µm - 8.5 µm. Thus, the current-carrying capacity of the negative electrode current collector is increased, and the energy density of the battery cell is improved.

[0041] According to some embodiments of the present application, the battery cell further includes an electrolyte, and the electrolyte includes a chain carboxylic acid ester. Based on the total mass of the electrolyte, the mass percentage of the chain carboxylic acid ester is 5% - 60%, and may be 8% - 30%. Thus, the viscosity of the electrolyte is reduced, the internal resistance of the battery cell is reduced, and the fast charging performance of the battery cell is improved.

[0042] According to some embodiments of the present application, the charging time of the battery cell configured to charge from 10% SOC to 80% SOC is 5 min - 10.5 min, and may be 7 min - 10 min. Thus, the fast charging performance of the battery cell is improved.

[0043] The second aspect of the present application provides a battery device, including the battery cell provided in the first aspect of the present application. The battery device is at least one of a battery module, a battery pack, and an energy storage device.

[0044] The third aspect of the present application provides an electrical device, including the battery cell provided by the first aspect of the present application or the battery device provided by the second aspect of the present application, and the battery cell or the battery device is used to provide electrical energy.

[0045] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present application. Moreover, in all the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0047] Figure 1 is a schematic structural diagram of a housing according to an embodiment of the present application.

[0048] Figure 2 is a schematic structural diagram of a cover plate assembly according to an embodiment of the present application.

[0049] Figure 3 is Figure 2 the exploded view of the cover plate assembly in

[0050] Figure 4 is Figure 2 the schematic structural diagram of another perspective of the cover plate assembly in

[0051] Figure 5 is Figure 4 the schematic cross-sectional view of the cover plate assembly along the AA' direction in

[0052] Figure 6 is a schematic structural diagram of another cover plate assembly of the present application.

[0053] Figure 7 is Figure 6 the exploded view of the cover plate assembly in

[0054] Figure 8 is Figure 6 the schematic structural diagram of another perspective of the cover plate assembly in

[0055] Figure 9 is Figure 8 the schematic cross-sectional view of the cover plate assembly along the BB' direction in

[0056] Figure 10 Schematic structural diagram of a battery cell according to an embodiment of the present application.

[0057] Figure 11 is Figure 10Schematic diagram of a cover plate assembly of a battery cell in

[0058] Figure 12 is Figure 11 Exploded view of the cover plate assembly in

[0059] Figure 13 is Figure 11 Schematic diagram of the cover plate assembly in another perspective in

[0060] Figure 14 is Figure 13 Cross-sectional schematic diagram of the cover plate assembly in along the CC’ direction

[0061] Figure 15 is Figure 10 Schematic diagram of another cover plate assembly of a battery cell in

[0062] Figure 16 is Figure 15 Exploded view of the cover plate assembly in

[0063] Figure 17 is Figure 15 Schematic diagram of the cover plate assembly in another perspective in

[0064] Figure 18 is Figure 17 Cross-sectional schematic diagram of the cover plate assembly in along the DD’ direction

[0065] Figure 19 Schematic diagram of the electrode assembly according to an embodiment of the present application.

[0066] Figure 20 Schematic diagram of the electrode assembly according to another embodiment of the present application.

[0067] Figure 21 Schematic diagram of the electrode assembly according to an embodiment of the present application.

[0068] Figure 22 Schematic diagram of the positive electrode tab according to an embodiment of the present application.

[0069] Figure 23 Schematic diagram of the positive electrode tab according to another embodiment of the present application.

[0070] Figure 24 Schematic diagram of the positive electrode tab according to another embodiment of the present application.

[0071] Figure 25 Schematic diagram of the positive electrode tab according to another embodiment of the present application.

[0072] Figure 26 Schematic diagram of the negative electrode tab according to an embodiment of the present application.

[0073] Figure 27 It is a schematic structural diagram of a negative electrode tab of another embodiment of the present application.

[0074] Figure 28 It is a schematic structural diagram of a negative electrode tab of another embodiment of the present application.

[0075] Figure 29 It is a schematic structural diagram of a negative electrode tab of another embodiment of the present application.

[0076] Figure 30 It is a schematic structural diagram of a positive electrode tab of an embodiment of the present application.

[0077] Figure 31 It is an SEM image of the positive electrode active material of an embodiment of the present application.

[0078] Figure 32 It is an SEM image of the positive electrode film layer of an embodiment of the present application.

[0079] Figure 33 It is a schematic structural diagram of a negative electrode tab of an embodiment of the present application.

[0080] Figure 34 It is a schematic diagram of an electrical device of the present application.

[0081] Explanation of reference numerals:

[0082] 1 Battery cell; 11 Housing; 12 Cover assembly; 1213 First cover; 1214 Second cover; 1210 Through hole; 1211 Liquid injection hole; 1212 Pressure relief mechanism; 1221 Electrode terminal; 1222 First limiting part; 1223 Second limiting part; 1224 Terminal body; 1225 Riveting block; 123 First insulating part; 1230 Through hole; 124 Sealing part; 125 Positioning part; 126 Second insulating part; 10 Electrode assembly; 2 Positive electrode tab; 21 Positive electrode current collector; 22 Positive electrode film layer; 221 Lithium-containing phosphate; 222 Lithium supplement agent; 23 Positive electrode tab ear; 231 First positive electrode tab ear; 232 Second positive electrode tab ear; 3 Negative electrode tab; 30 Negative electrode current collector; 31 Negative electrode film layer; 311 First negative electrode film layer; 312 Second negative electrode film layer; 32 Negative electrode tab ear; 321 First negative electrode tab ear; 322 Second negative electrode tab ear; 4 Separator film. Detailed description of specific embodiments

[0083] The embodiments of the technical solutions of the present application will be described in detail below. The following embodiments are only used to illustrate the technical solutions of the present application more clearly, so they are only examples and cannot be used to limit the protection scope of the present application.

[0084] Reference to "embodiments" in this document means that the specific features, structures, or characteristics described in connection with the embodiments may be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment each time, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0085] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0086] Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0087] Unless otherwise specified, all steps of the present application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out sequentially, or may also include steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or may also include steps (a), (c), and (b), or may also include steps (c), (a), and (b), etc.

[0088] Currently, from the perspective of the development of the market situation, the application of batteries is becoming more and more extensive. Batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in many fields such as military equipment and aerospace. With the continuous expansion of the application fields of batteries, the market demand for them is also continuously increasing. The battery monomers in the related technologies cannot meet the requirements of fast charging and long cycle life.

[0089] This application aims to develop a battery cell containing lithium phosphate with high energy density, excellent fast charging performance, and long cycle life. When charging the battery cell at the same charging rate, the higher the volumetric energy density of the battery cell, the more heat is generated, and the generated heat needs to be dissipated through the electrode terminal on the cover plate assembly. That is, the higher the volumetric energy density, the higher the requirement for the overcurrent capacity of the electrode terminal. For the battery cell proposed in this application, when the positive electrode active material is a lithium phosphate-containing material, within the capacity range of the lithium phosphate-containing material, by keeping the ratio of the volumetric energy density VED of the battery cell to the minimum cross-sectional area S of the electrode terminal within a certain range, it is possible to reduce the heat generation of the electrode terminal, reduce the internal resistance of the battery cell, and improve the cycle performance of the battery while the battery cell has a high energy density. If the ratio of VED to S is too small, the overcurrent capacity of the electrode terminal is poor, and more heat is generated at the electrode terminal during high-rate charging, which will reduce the cycle life of the battery cell; if the ratio of VED to S is too large, the volumetric energy density of the battery cell is small, which will reduce the capacity of the battery cell.

[0090] The battery cell proposed in this application can be used in electrical equipment that uses the battery cell as a power source or various energy storage systems that use the battery cell as an energy storage element. The electrical equipment can include, but is not limited to, mobile phones, tablets, laptop computers, electric toys, power tools, battery cars, electric vehicles, ships, spacecraft, and so on. Among them, the electric toys can include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric aircraft toys, etc., and the spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0091] In the first aspect of this application, a battery cell is provided. The battery cell includes a first wall, and the housing has a receiving cavity; an electrode terminal is disposed on the first wall, and the minimum cross-sectional area of the electrode terminal is S; an electrode assembly is disposed in the receiving cavity, the electrode assembly includes a positive electrode tab, the positive electrode tab includes a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector, and the positive electrode film layer includes lithium phosphate; wherein, the ratio of the volumetric energy density VED of the battery cell to the S is 2 Wh / L / mm 2 to 10 Wh / L / mm 2 .

[0092] In this application, the minimum cross-sectional area of the electrode terminal refers to the minimum cross-sectional area of the electrode terminal along the direction perpendicular to the current flow direction.

[0093] In this application, the test method for the volume energy density of a battery cell is as follows: Place the battery cell at room temperature, charge it at a constant current of 0.33C to 3.65V, then charge it at a constant voltage of 3.65V to 0.05C, and let it stand for 30 minutes; discharge it at a constant current of 0.33C to 2.0V, record the discharge capacity A0 at this time, unit: Ah, and calculate the discharge platform voltage, unit: V; the volume of the battery cell refers to the outer volume of the housing, measure the length, width, and thickness of the housing using a caliper (without calculating the dimensions of the electrode terminals extending outside the housing), and calculate the volume V0 of the single battery cell, unit: L; the volume energy density VED of the battery cell = (A0 × discharge platform voltage) / V0, unit: Wh / L.

[0094] In some embodiments, the volume energy density of the battery cell can be adjusted by the following optional methods:

[0095] From the perspective of the active material, positive and negative active materials with high specific capacity can be used. For example, for the positive active material, lithium-containing phosphate materials with higher gram capacity are used. For instance, physically mix positive active materials with higher gram capacity, such as ternary materials, to increase the energy density; for example, for the negative active material, graphite with higher gram capacity is used. For instance, physically mix negative active materials with higher gram capacity, such as silicon-based materials, etc.;

[0096] From the perspective of the electrolyte, reduce the injection volume of the electrolyte, or use an electrolyte that supports a higher energy density, etc.;

[0097] From the perspective of the electrode sheet design, the compaction density and coating weight of the positive electrode sheet or the negative electrode sheet can be adjusted, or the thickness of the positive current collector or the negative current collector can be adjusted, etc.;

[0098] In terms of the separator, the thickness of the separator can be adjusted, etc.;

[0099] In terms of the structural design, first, the proportion of non-active substances such as battery components can be reduced. For example, make the battery housing thinner while ensuring its safety and mechanical properties, so that more active substances can be accommodated in the same space, increasing the energy density. For instance, adjust the space occupancy ratio of the electrode assembly in the housing cavity.

[0100] It should be noted that the first wall can be a part of the housing, or the first wall is a separate structural member.

[0101] Reference Figures 1 - 5, the battery cell 1 includes a housing 11 and a cover assembly 12. The cover assembly 12 forms the first wall. The cover assembly 12 is disposed at at least one end of the housing 11. The housing 11 and the cover assembly 12 define a receiving cavity. The cover assembly 12 includes a cover plate and an electrode terminal 1221. Wherein, the minimum cross-sectional area of the electrode terminal 1221 is S; an electrode assembly, the electrode assembly is disposed in the receiving cavity. The electrode assembly includes a positive electrode plate. The positive electrode plate includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a lithium-containing phosphate. Wherein, the ratio of the volumetric energy density VED of the battery cell 1 to the S is: 2 Wh / L / mm 2 to 10 Wh / L / mm 2 . Thus, by making the ratio of the volumetric energy density VED of the battery cell 1 to S within the above range, the heat generation of the electrode terminal 1221 is reduced during the fast charging process, and a battery cell 1 with good fast charging performance and cycle life is obtained.

[0102] When the cover assembly forms the first wall, the minimum cross-sectional area of the electrode terminal refers to the minimum cross-sectional area of the electrode terminal along the direction perpendicular to the current flow direction, and the current flow direction is parallel to the thickness direction of the cover plate.

[0103] Specifically, the cover assembly 12 can be disposed at at least one end of the housing 11 along its length direction, or the cover assembly 12 is disposed at at least one end of the housing 11 along its width direction.

[0104] As an example, referring to Figure 1 , the cover assembly 12 can be disposed at both ends of the housing 11 along its length direction; or the cover assembly 12 can be disposed at both ends of the housing 11 along its width direction. Specifically, when both ends of the housing 11 along its length direction have openings, the cover assembly 12 can be disposed at both ends of the housing 11 along its length direction and is adapted to respectively cover the openings; when both ends of the housing 11 along its width direction have openings, the cover assembly 12 can be disposed at both ends of the housing 11 along its width direction and is adapted to respectively cover the openings to isolate the internal environment of the battery cell from the external environment. The shape of the cover assembly 12 can be adapted to the shape of the housing 11 to cooperate with the housing 11.

[0105] In some embodiments, the cover assembly 12 can be disposed at both ends of the housing 11 along its length direction, that is, the cover assembly 12 is disposed on the smaller side surface of the housing 11, thereby saving the space of the battery cell along the width direction, so as to accommodate wider electrode plates and improve the energy density of the battery cell.

[0106] In some embodiments, the housing 11 is formed by bending and then welding and splicing, and the weld marks are integrated on the smaller side surface of the housing 11 extending along the length direction, which helps to reduce the problem of cracking of the welding area caused by the expansion of the battery cell along the thickness direction and improve the reliability of the housing 11.

[0107] Reference Figures 2 - 5 , the cover assembly 12 includes a first cover 1213 and an electrode terminal 1221.

[0108] In some embodiments, reference Figure 3 to the disassembly schematic diagram of the cover assembly 12 in Figure 2 shown, the cover assembly 12 includes a first cover 1213, an electrode terminal 1221, a first insulating member 123, a sealing member 124, a second insulating member 126, a riveting block 1225, and a positioning member 125, and is assembled into

[0109] shown cover assembly 12. Figure 5 is Figure 4 the cross-sectional schematic diagram of the cover assembly in Figure 5 along the AA' direction, in combination with Figure 3 it can be seen that a through hole 1210 is provided on the first cover 1213, the electrode terminal 1221 penetrates through the first cover 1213, a first insulating member 123 is provided between the first cover 1213 and the electrode terminal 1221. This assembly method is used to isolate the electrical connection components in the housing 11 from the first cover 1213 on the one hand, and at the same time make the electrode terminal 1221 and the first cover 1213 in an insulating state to reduce the risk of short circuit. A through hole 1230 is provided on the first insulating member 123, the electrode terminal 1221 sequentially passes through the through hole 1230 and the through hole 1210, and a sealing member 124 for insulation and sealing is provided between the through hole 1210 and the electrode terminal 1221. An opening is provided on the sealing member 124 so that the electrode terminal 1221 can pass through. A second insulating member 126 and a riveting block 1225 are provided on the side of the first cover 1213 away from the electrode assembly. Openings are also provided on the second insulating member 126 and the riveting block 1225, and the electrode terminal 1221 sequentially passes through the openings of the second insulating member 126 and the riveting block 1225. Among them, the second insulating member 126 is used to insulate the electrode terminal 1221 and the first cover 1213, and the riveting block 1225 is used to fix the electrode terminal 1221 on the first cover 1213.

[0110] In some embodiments, reference Figure 3, the cover plate assembly 12 further includes positioning members 125. There are at least two positioning members 125 to prevent the electrode terminals 1221 from deflecting and improve the stress strength of the electrode terminals 1221.

[0111] In some embodiments, refer to Figure 4 , the cover plate assembly includes a liquid injection hole 1211 for injecting electrolyte into the accommodation cavity of the housing 11.

[0112] Refer to Figures 6 - 9 , the cover plate assembly 12 includes a second cover plate 1214 and electrode terminals 1221.

[0113] In some embodiments, refer to Figure 7 The disassembly schematic diagram of the cover plate assembly 12 in. The cover plate assembly 12 includes a second cover plate 1214, electrode terminals 1221, a first insulating member 123, a sealing member 124, a second insulating member 126, a riveting block 1225, and positioning members 125, and is assembled into Figure 6 the shown cover plate assembly 12.

[0114] In some embodiments, Figure 9 is Figure 8 The cross-sectional schematic diagram of the cover plate assembly in along the BB' direction. Combining Figure 7 and Figure 9 it can be seen that a through hole 1210 is provided on the second cover plate 1214, the electrode terminals 1221 penetrate through the second cover plate 1214, a first insulating member 123 is provided between the second cover plate 1214 and the electrode terminals 1221. This assembly method is used to isolate the electrical connection components in the housing 11 from the second cover plate 1214 on the one hand, and at the same time keep the electrode terminals 1221 and the second cover plate 1214 in an insulating state to reduce the risk of short circuit. A through hole 1230 is provided on the first insulating member 123, and the electrode terminals 1221 sequentially pass through the through hole 1230 and the through hole 1210. A sealing member 124 for insulation and sealing is provided between the through hole 1210 and the electrode terminals 1221. An opening is provided on the sealing member 124 so that the electrode terminals 1221 can pass through. A second insulating member 126 and a riveting block 1225 are provided on the side of the second cover plate 1214 away from the electrode assembly. The second insulating member 126 and the riveting block 1225 are also provided with openings. The electrode terminals 1221 sequentially pass through the openings of the second insulating member 126 and the riveting block 1225. Among them, the second insulating member 126 is used to insulate the electrode terminals 1221 and the second cover plate 1214, and the riveting block 1225 is used to fix the electrode terminals 1221 on the second cover plate 1214.

[0115] In some embodiments, refer to Figure 7, the cover assembly 12 further includes positioning members 125, and there are at least two positioning members 125 to prevent the electrode terminals 1221 from deflecting and improve the stress intensity of the electrode terminals 1221.

[0116] In this application, with reference to Figure 3 and Figure 7 , the electrode terminal 1221 includes a terminal body 1224, a first limiting portion 1222 and a second limiting portion 1223. The terminal body 1224 passes through the through hole 1210 and connects the first limiting portion 1222 and the second limiting portion 1223. Among them, since the first limiting portion 1222 and the second limiting portion 1223 play a limiting role, their cross-sectional areas are larger than the cross-sectional area of the terminal body 1224. The cross-sectional area of the terminal body 1224 is often smaller, which also becomes the overcurrent bottleneck during charge and discharge. This application precisely starts from matching electrode terminals with appropriate overcurrent capabilities for battery cells with different energy densities to obtain the technical solution of this application.

[0117] In some embodiments, the cross-sectional area of the first limiting portion 1222 is larger than the cross-sectional area of the second limiting portion 1223, which can improve the overcurrent capability of the electrode terminal 1221 and enhance the mechanical strength of the electrode terminal 1221.

[0118] As an example, the cover can be made of a material with a certain hardness and strength (such as aluminum alloy) to make the cover have higher strength. When the cover is squeezed, the deformation of the cover is reduced, and the safety performance of the battery cell is improved. In some embodiments, it can be selected as a steel shell.

[0119] As an example, the cover assembly 12 and the housing 11 can be independent components.

[0120] As an example, the cover assembly 12 and the housing 11 can also be integrated. Specifically, at least one cover assembly 12 and the housing 11 can form a common connection body before the electrode assembly and other components are put into the housing. After the electrode assembly and other components are put into the housing 11, the cover assembly 12 is then used to cover the opening of the housing along its length direction (or width direction).

[0121] In this application, the first insulating member 123 and the second insulating member 126 can be independently plastics, rubbers, etc.

[0122] As an example, with reference to Figure 6 and Figure 7, the cover plate assembly 12 further includes a pressure relief mechanism 1212. The pressure relief mechanism 1212 and the second cover plate 1214 are two separate components, and they are installed together after being separately formed. The pressure relief mechanism 1212 can be components such as an explosion-proof film, an explosion-proof valve, a safety valve, etc. The pressure relief mechanism 1212 can be installed on the second cover plate 1214 by means of bonding, welding, etc. When the internal pressure of the battery cell reaches the threshold value, the pressure relief mechanism 1212 opens at least part of the pressure relief holes, and the discharge cut-off inside the battery cell is discharged through the pressure relief holes to relieve the internal pressure of the battery cell.

[0123] As an example, the ratio of the volume energy density VED of the battery cell to the S can be 2 Wh / L / mm 2 , 3 Wh / L / mm 2 , 5 Wh / L / mm 2 , 7 Wh / L / mm 2 , 9 Wh / L / mm 2 , 10 Wh / L / mm 2 etc., or can be a range composed of any of the above values. Thus, the heat generation of the electrode terminal 1221 is further reduced, and a battery cell with excellent fast charging performance and cycle life is obtained. According to some specific embodiments of the present application, the ratio of the volume energy density VED of the battery cell to the S can be 2 Wh / L / mm 2 to 3.5 Wh / L / mm 2 .

[0124] According to some embodiments of the present application, the volume energy density VED of the battery cell satisfies: 350 Wh / L ≤ VED ≤ 430 Wh / L. For example, it can be 350 Wh / L, 380 Wh / L, 390 Wh / L, 400 Wh / L, 410 Wh / L, 420 Wh / L, 430 Wh / L, etc., or can be a range composed of any of the above values. Thus, the capacity of the battery cell 1 is improved.

[0125] According to some embodiments of the present application, the minimum cross-sectional area S of the electrode terminal satisfies: 40 mm 2 ≤ S ≤ 800 mm 2 , for example, it can be 40 mm 2 , 100 mm 2 , 200 mm 2 , 400 mm 2 , 600 mm 2 , 800 mm 2 etc., or can be a range composed of any of the above values.

[0126] According to some embodiments of the present application, when the cross-sectional area of the terminal body 1224 is smaller than the cross-sectional area of the first limiting portion 1222 and the second limiting portion 1223, the minimum cross-sectional area S of the electrode terminal is the cross-sectional area of the terminal body 1224. Thus, the current capacity of the electrode terminal 1221 is improved, the resistance is reduced, the heat generation of the electrode terminal 1221 is reduced, the fast charging performance of the battery cell 1 is improved, and the electrode terminal can be more stably fixed on the cover plate through the first limiting portion 1222 and the second limiting portion 1223.

[0127] According to some embodiments of the present application, reference Figure 3 and Figure 7 The electrode terminal 1221 includes a terminal body 1224, a first limiting portion 1222, and a second limiting portion 1223. The terminal body 1224 passes through the through hole 1210 and connects the first limiting portion 1222 and the second limiting portion 1223. The first limiting portion 1222 is located on the side of the cover plate facing the accommodating cavity, and the second limiting portion 1223 is located on the side of the cover plate away from the accommodating cavity. Thus, the first limiting portion 1222 can limit the electrode terminal 1221 from escaping from the through hole 1210 in the direction away from the electrode assembly, and the second limiting portion 1223 can limit the electrode terminal 1221 from escaping from the through hole 1210 in the direction toward the electrode assembly, so that the battery cell 1 can normally input or output electrical energy, thereby extending the service life of the battery cell 1.

[0128] According to some embodiments of the present application, the cross-sectional area of the second limiting portion 1223 is 300 mm 2 Up to 700mm 2 , for example, it can be 300mm 2 , 400mm 2 , 500mm 2 、600mm 2 、700mm 2 etc., or can be a range of any of the above values. Thus, the current capacity of the electrode terminal 1221 is improved and the heat generation of the electrode terminal 1221 is reduced.

[0129] In the present application, the cross-sectional area of the second limiting portion refers to the cross-sectional area of the second limiting portion along a direction perpendicular to the current flow direction, and the current flow direction is parallel to the thickness direction of the cover plate.

[0130] According to some embodiments of the present application, the cross-sectional area of the first limiting portion 1222 is 200 mm 2 Up to 800mm 2 , for example, it can be 200mm 2 , 400mm 2 , 500mm 2 、600mm 2, 700 mm 2 , 800 mm 2 etc., or can be a range composed of any of the above values. Thus, the overcurrent capacity of the electrode terminal 1221 is improved, and the heat generation of the electrode terminal 1221 is reduced.

[0131] In this application, the cross-sectional area of the first limiting portion refers to the cross-sectional area of the first limiting portion along the direction perpendicular to the current flow direction, and the current flow direction is parallel to the thickness direction of the cover plate.

[0132] According to some embodiments of the present application, referring to Figure 3 and Figure 7 , along the direction perpendicular to the current flow direction, the cross-section of the terminal body 1224 is a rounded rectangle. Thus, in the case of a small cover plate area, the overcurrent capacity of the electrode terminal is improved.

[0133] According to some embodiments of the present application, along the direction perpendicular to the current flow direction, the cross-sectional area of the terminal body 1224 is 40 mm 2 to 240 mm 2 , for example, can be 40 mm 2 , 70 mm 2 , 100 mm 2 , 120 mm 2 , 140 mm 2 , 160 mm 2 , 180 mm 2 , 200 mm 2 , 220 mm 2 , 240 mm 2 etc., or can be a range composed of any of the above values. Thus, the overcurrent capacity of the electrode terminal 1221 is improved, and the heat generation of the electrode terminal 1221 is reduced.

[0134] In this application, when testing the area of the cross-section of the terminal body 1224, it can be the area of the cross-section at any position between the first limiting portion 1222 and the second limiting portion 1223 along the direction perpendicular to the current flow direction.

[0135] Specifically, when the cross-section of the terminal body is a rounded rectangle, the length and width of the cross-section and the radii of the 1 / 4 circles of the four feet can be measured with a ruler, and the area of the cross-section is the sum of the area of the rectangle and the area of the circle, and is specifically calculated using a general mathematical calculation formula.

[0136] According to some embodiments of the present application, the cover plate assemblies 12 are disposed at both ends of the housing 11, and each cover plate assembly 12 includes at least two of the electrode terminals 1221. Specifically, the cover plate assemblies 12 may be disposed at both ends in the length direction or both ends in the width direction of the housing 11, and each cover plate assembly 12 includes two electrode terminals 1221 with the same or opposite polarities. Thereby, the resistance of the battery cell 1 is reduced, and the current-carrying capacity of the battery cell 1 is improved.

[0137] According to some embodiments of the present application, the cover plate assemblies are disposed at both ends of the housing, and each cover plate assembly includes at least two of the electrode terminals, and the two electrode terminals have opposite polarities. In the length direction of the battery cell, the electrode terminals with the same polarity on the two cover plate assemblies are arranged in a staggered manner.

[0138] According to some embodiments of the present application, the electrode terminals with the same polarity are arranged diagonally in the length direction of the battery cell.

[0139] Thereby, during charging, the temperature rise of the battery cell can be reduced, and further the impedance of the battery cell can be reduced.

[0140] As an example, referring to Figure 1 and Figure 10 , the cover plate assemblies 12 are disposed at both ends in the length direction of the housing 11, and each cover plate assembly 12 includes two electrode terminals 1221 with opposite polarities.

[0141] Referring to Figures 11 - 14 , the cover plate assembly 12 includes a first cover plate 1213 and two electrode terminals 1221 with opposite polarities.

[0142] In some embodiments, referring to Figure 12 the disassembly schematic diagram of the cover plate assembly 12 in Figure 11 , the cover plate assembly includes a first cover plate 1213, two electrode terminals 1221, a first insulating member 123, two sealing members 124, two second insulating members 126, two riveting blocks 1225, and four positioning members 125, and are assembled into the cover plate assembly 12 shown in

[0143] In some embodiments, Figure 14 is Figure 13 a cross-sectional schematic diagram along the CC' direction. Combining Figure 12 and Figure 14It can be seen that two through holes 1210 are provided on the first cover plate 1213, and both of the two electrode terminals 1221 penetrate through the first cover plate 1213. A first insulating member 123 is provided between the first cover plate 1213 and the two electrode terminals 1221. This assembly method is used on the one hand to isolate the electrical connection components in the housing 11 from the first cover plate 1213, and at the same time to insulate the electrode terminals 1221 from the first cover plate 1213 to reduce the risk of short circuit. Two through holes 1230 are provided on the first insulating member 123, and the two electrode terminals 1221 respectively pass through the through holes 1230 and the through holes 1210 in sequence. Sealing members 124 for insulation and sealing are provided between the through holes 1210 and the two electrode terminals 1221. The sealing members 124 are provided with openings through which the electrode terminals 1221 can pass. On the side of the first cover plate 1213 away from the electrode assembly, two second insulating members 126 and two riveting blocks 1225 are provided. The second insulating members 126 and the riveting blocks 1225 are also provided with openings, and the electrode terminals 1221 pass through the openings of the second insulating members 126 and the riveting blocks 1225 in sequence. Among them, the second insulating member 126 is used to insulate the electrode terminals 1221 from the first cover plate 1213, and the two riveting blocks 1225 respectively fix the two electrode terminals 1221 on the first cover plate 1213. A liquid injection hole 1211 is provided on the first cover plate 1213, which can be used to inject electrolyte into the housing interior.

[0144] Reference Figures 15 - 18 , the cover plate assembly 12 includes a second cover plate 1214 and two electrode terminals 1221.

[0145] In some embodiments, reference Figure 16 to the disassembly schematic diagram of the cover plate assembly 12 in Figure 15 shown, the cover plate assembly 12 includes a second cover plate 1214, two electrode terminals 1221, a first insulating member 123, two sealing members 124, two second insulating members 126, two riveting blocks 1225, and four positioning members 125, and are assembled into

[0146] In some embodiments, Figure 18 is Figure 17 a cross-sectional schematic diagram along the DD' direction. Combining Figure 16 and Figure 18It can be seen that two through holes 1210 are provided on the second cover plate. The two electrode terminals 1221 respectively penetrate through the second cover plate 1214. A first insulating member 123 is provided between the second cover plate 1214 and the electrode terminals 1221. This assembly method is used to isolate the electrical connection components in the housing 11 from the second cover plate 1214 on one hand, and at the same time keep the electrode terminals 1221 insulated from the second cover plate to reduce the risk of short circuit. Two through holes 1230 are provided on the first insulating member 123. The two electrode terminals 1221 respectively pass through the corresponding through holes 1230 and the through holes 1210. Sealing members 124 for insulation and sealing are provided between the through holes 1210 and the electrode terminals 1221. The sealing members 124 are provided with openings through which the electrode terminals 1221 can pass. On the side of the second cover plate 1214 away from the electrode assembly, two second insulating members 126 and two riveting blocks 1225 are provided. The second insulating members 126 are also provided with openings. The electrode terminals 1221 sequentially pass through the openings on the second insulating members 126 and the riveting blocks 1225. Among them, the second insulating members 126 are used to insulate the electrode terminals 1221 from the second cover plate 1214, and the two riveting blocks 1225 are used to fix the two electrode terminals 1221 on the second cover plate 1214. A pressure relief mechanism 1212 is provided on the second cover plate 1214. When the internal pressure of the housing exceeds the threshold, the pressure relief mechanism 1212 can release the internal pressure of the housing.

[0147] Reference Figure 19 , the electrode assembly 10 includes four tab ears. Two tab ears extend from one end of the electrode assembly 10 in the length direction, namely the first positive tab ear 231 and the first negative tab ear 321. Two tab ears extend from the other end of the electrode assembly 10 in the length direction, namely the second positive tab ear 232 and the second negative tab ear 322. The first positive tab ear 231 is electrically connected to the positive terminal on the first cover plate, the first negative tab ear 321 is electrically connected to the negative terminal on the first cover plate, the second positive tab ear 232 is electrically connected to the positive terminal on the second cover plate, and the second negative tab ear 322 is electrically connected to the negative terminal on the second cover plate. Thus, the electrode terminals with different polarities are arranged diagonally in the length direction of the battery cell. During charging, the temperature rise of the battery cell can be reduced, and further the impedance of the battery cell can be reduced.

[0148] Reference Figure 20, the electrode assembly 10 includes four tab ears. At one end in the length direction of the electrode assembly 10, two tab ears extend out, namely the first positive tab ear 231 and the first negative tab ear 321. At the other end in the length direction of the electrode assembly 10, two tab ears extend out, namely the second positive tab ear 232 and the second negative tab ear 322. The first positive tab ear 231 is electrically connected to the positive terminal on the first cover plate, the first negative tab ear 321 is electrically connected to the negative terminal on the first cover plate, the second positive tab ear 232 is electrically connected to the positive terminal on the second cover plate, and the second negative tab ear 322 is electrically connected to the negative terminal on the second cover plate. That is, the electrode terminals on each cover plate are electrode terminals of different polarities, and there are a total of four electrode terminals on the battery cell. Thus, while improving the over-current capacity of the battery cell, problems such as unreasonable wire routing and too long wire harness caused by electrical connection between battery cells when multiple battery cells are assembled into a battery pack can be reduced, and it is easier to assemble.

[0149] According to some embodiments of the present application, referring to Figure 21 , the electrode assembly 10 further includes a negative electrode plate 3. The positive electrode plate 2 and the negative electrode plate 3 are stacked, and a separator 4 is arranged between the positive electrode plate 2 and the negative electrode plate 3. A positive tab ear is arranged on each positive electrode plate, and a negative tab ear is arranged on each negative electrode plate. Thus, the current transmission efficiency is improved, the resistance of the battery cell 1 is reduced, and the rate performance of the battery is improved.

[0150] According to some embodiments of the present application, the positive tab ear extends out along the length direction or the width direction of the positive electrode plate.

[0151] Referring to Figure 22 , only one tab ear extends out along the length direction of the positive electrode plate 2. Referring to Figure 23 , positive tab ears extend out at both ends along the length direction of the positive electrode plate 2.

[0152] Referring to Figure 24 , the positive tab ear 23 extends out from one end along the width direction of the positive electrode plate 2. At this time, the dimension of the positive tab ear 23 along the length direction of the positive electrode plate 2 can occupy 70%-90% of the total length of the positive electrode plate 2, so as to improve the over-current capacity of the battery cell.

[0153] In some embodiments, the electrical connection between the positive tab ear 23 and the electrode terminals on the two cover plate assemblies arranged along the length direction of the battery cell can be realized by welding an L-shaped adapter piece on the positive tab ear 23.

[0154] Referring to Figure 25 , the first positive tab ear 231 and the second positive tab ear 232 are respectively arranged on both sides of the positive electrode plate 2 along its width direction.

[0155] According to some embodiments of the present application, the negative electrode tab can extend from the negative electrode sheet along its length direction or along its width direction. Thereby, the current transmission efficiency is improved, the resistance of the battery cell 1 is reduced, and the rate performance of the battery cell is improved.

[0156] Reference Figure 26 , the negative electrode tab 32 extends from the negative electrode sheet 3 along the length direction; Reference Figure 27 , the negative electrode tab extends along the length direction of the negative electrode sheet 3 to respectively form a first negative electrode tab 321 and a second negative electrode tab 322.

[0157] Reference Figure 28 , the negative electrode tab 32 extends from the negative electrode sheet 3 along the width direction. At this time, the dimension of the negative electrode tab 23 along the length direction of the negative electrode sheet 3 can occupy 70%-90% of the total length of the negative electrode sheet 3, thereby improving the overcurrent capacity of the battery cell.

[0158] Reference Figure 29 , the first negative electrode tab 321 and the second negative electrode tab 322 are respectively arranged on both sides of the negative electrode sheet along its width direction.

[0159] In some embodiments, an L-shaped adapter can be welded to the negative electrode tab 32 to achieve electrical connection with the electrode terminals on the two cover plate assemblies arranged along the length direction of the battery cell.

[0160] In some embodiments, the battery cell of the present application is a stacked battery, the positive electrode sheet and the negative electrode sheet are stacked, a positive electrode tab is arranged on each positive electrode sheet, and a negative electrode tab is arranged on each negative electrode sheet.

[0161] According to some embodiments of the present application, Reference Figure 30 , the positive electrode sheet 2 includes a positive electrode current collector 21, at least one side of the positive electrode current collector is provided with a positive electrode film layer 22. Along the length direction of the positive electrode sheet, the coating length L of the positive electrode film layer is 200 mm - 700 mm. For example, it can be 200 mm, 300 mm, 400 mm, 450 mm, 500 mm, 550 mm, 600 mm, 650 mm, 700 mm, etc., or it can be a range composed of any of the above values. Thereby, the energy density of the battery cell 1 is improved.

[0162] In the present application, the coating length of the positive electrode film layer can be measured by a ruler or a meter stick, etc.

[0163] According to some embodiments of the present application, the compaction density of the positive electrode film layer corresponding to the battery cell 1 at 100% SOC is 2.5 g / cm 3 - 2.8 g / cm 3 , for example, it can be 2.5 g / cm3 , 2.55 g / cm 3 , 2.6 g / cm 3 , 2.65 g / cm 3 , 2.7 g / cm 3 , 2.75 g / cm 3 , 2.8 g / cm 3 etc., or can be a range composed of any of the above values. Thus, when the compaction density of the positive electrode film layer is within the above range, the stacking of the positive electrode sheet is relatively dense, which is beneficial to improving the energy density of the battery cell 1, and the contact resistance between particles is small, which can further reduce the internal resistance of the battery cell 1, reduce the heat generation of the battery cell 1, and improve the high-temperature performance of the battery cell 1.

[0164] The present application provides a method for testing the compaction density of a positive electrode film layer: charge at a constant current of 1 / 3C to 3.8V, charge at a constant voltage of 3.8V to 0.05C, disassemble the battery cell 1 to obtain the positive electrode sheet. For example, take a single-sided coated positive electrode sheet (if it is a double-sided coated sheet, the positive electrode film layer on one side can be wiped off first), punch it into small round pieces with an area of S1, weigh it, record it as M1, and measure its thickness H1. Then wipe off the positive electrode film layer of the above-mentioned weighed positive electrode sheet, weigh the weight of the positive electrode current collector, record it as M0, and measure its thickness H0. The single-sided coating weight of the positive electrode film layer = (M1 - M0) / S1, the thickness of the positive electrode film layer = H1 - H0, and the compaction density of the positive electrode film layer = the single-sided coating weight of the positive electrode film layer / the thickness of the positive electrode film layer.

[0165] According to some embodiments of the present application, the single-sided coating weight of the positive electrode film layer is 200 mg / 1540.25 mm 2 -340 mg / 1540.25 mm 2 , for example, can be 200 mg / 1540.25 mm 2 , 230 mg / 1540.25 mm 2 , 260 mg / 1540.25 mm 2 , 290 mg / 1540.25 mm 2 , 320 mg / 1540.25 mm 2 , 340 mg / 1540.25 mm 2 etc., or can be a range composed of any of the above values. Thus, by making the size of the positive electrode film layer 300 mm - 600 mm and at the same time making the coating weight of the positive electrode film layer within the above range, the energy density of the battery cell 1 can be improved. According to some specific embodiments of the present application, the single-sided coating weight of the positive electrode film layer can be 240 mg / 1540.25 mm 2 -300 mg / 1540.25 mm 2 .

[0166] The present application provides a method for testing the coating weight of the positive electrode film layer: the positive electrode plate is disassembled from the battery cell 1. For example, a single-sided coated positive electrode plate is taken (if it is a double-sided coated plate, the positive electrode film layer on one side can be wiped off first), and cut into small round pieces with an area of S1, and its weight is weighed and recorded as M1. Then, the positive electrode film layer of the above-mentioned weighed positive electrode plate is wiped off, and the weight of the positive electrode current collector is weighed and recorded as M0. The single-sided coating weight of the positive electrode film layer = (M1 - M0) / S1.

[0167] According to some embodiments of the present application, the charging gram capacity of the lithium-containing phosphate at a rate of 0.1C is 150 mAh / g - 170 mAh / g. Thereby, the energy density of the battery cell 1 is increased.

[0168] According to some embodiments of the present application, the lithium-containing phosphate includes the compound shown in Formula I: Li x1 A y1 Me a M b P 1-c X c Y z Formula I, wherein, 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, and 0.9 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a ≤ 1.5, 0 ≤ b ≤ 0.5, and 0.9 ≤ a + b ≤ 1.5, 0 ≤ c ≤ 0.5, 3 ≤ z ≤ 5, A includes one or more of Na, K, Mg, Me includes one or more of Mn, Fe, Co, Ni, M includes one or more of B, Mg, Al, P, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, X includes one or more of S, Si, Cl, B, C, N, and Y includes one or two of O, F. Thereby, the safety performance and cycle life of the battery cell 1 are improved.

[0169] As an example, x1 can be 0.5, 0.7, 0.9, 1.1, 1.3, etc., or can be a range composed of any of the above values.

[0170] As an example, y1 can be 0, 0.3, 0.6, 0.9, 1.1, 1.3, etc., or can be a range composed of any of the above values.

[0171] As an example, a can be 0.9, 1.1, 1.3, 1.5, etc., or can be a range composed of any of the above values.

[0172] As an example, b can be 0, 0.2, 0.4, 0.5, etc., or can be a range composed of any of the above values.

[0173] As an example, c can be 0, 0.2, 0.4, 0.5, etc., or can be a range composed of any of the above numerical values.

[0174] As an example, z can be 3, 3.5, 4, 4.5, 5, etc., or can be a range composed of any of the above numerical values.

[0175] According to some embodiments of the present application, the lithium-containing phosphate includes lithium iron phosphate material. Thereby, the safety and cycle performance of the battery cell 1 are improved.

[0176] According to some embodiments of the present application, the lithium-containing phosphate is granular, and the volume average particle size Dv50 of the lithium-containing phosphate is 1 µm - 2 µm. For example, it can be 1 µm, 1.2 µm, 1.4 µm, 1.6 µm, 1.8 µm, 2 µm, etc., or can be a range composed of any of the above numerical values. Thereby, the volume average particle size of the lithium-containing phosphate with olivine structure is small, which can shorten the migration path of lithium ions in the solid phase, reduce the polarization of the battery cell 1, reduce heat generation, and improve the high-temperature performance of the battery cell 1.

[0177] In the present application, Dv50 refers to the particle size corresponding to the cumulative volume distribution percentage reaching 50%. For example, referring to the standard GB / T 19077-2016 / ISO 13320:2009, it is measured using a laser particle size analyzer (Malvern Master Size 2000). The specific test process is as follows: scrape the positive electrode film layer powder, calcine it at high temperature in an air atmosphere, grind it into powder, after sieving, take an appropriate amount of the sample to be tested (the sample concentration only needs to ensure a light transmittance of 8% - 12%), add deionized water, and at the same time perform ultrasonic dispersion to ensure that the sample is completely dispersed, and then measure the sample according to the standard of GB / T19077-2016 / ISO 13320:2009.

[0178] According to some embodiments of the present application, the volume particle size Dv10 of the lithium-containing phosphate is 0.4 µm - 0.7 µm. For example, it can be 0.4 µm, 0.5 µm, 0.6 µm, 0.7 µm, etc., or can be a range composed of any of the above numerical values. Thereby, the volume particle size Dv10 of the lithium-containing phosphate with olivine structure is small, which can shorten the migration path of lithium ions in the solid phase, reduce the polarization of the battery cell 1, reduce heat generation, and improve the high-temperature performance of the battery cell 1.

[0179] In this application, Dv10 refers to the particle size corresponding to a cumulative volume distribution percentage of 10%. For example, referring to the standard GB / T 19077-2016 / ISO 13320:2009, it is measured using a laser particle size analyzer (Malvern Master Size 2000). The specific test process is as follows: Scrape off the positive electrode film layer powder, calcine it at high temperature in an air atmosphere, grind it into powder, and after sieving, take an appropriate amount of the sample to be tested (the sample concentration only needs to ensure a light transmittance of 8%-12%), add deionized water, and disperse it ultrasonically at the same time to ensure that the sample is completely dispersed. Then, the sample is measured according to the standard GB / T19077-2016 / ISO 13320:2009.

[0180] According to some embodiments of the present application, referring to Figure 31 , the lithium-containing phosphate includes secondary particles, and the average particle size of the primary particles in the secondary particles is 200nm - 500nm. For example, it can be 200nm, 300nm, 400nm, 500nm, etc., or it can be a range composed of any of the above values. Thus, the migration path of lithium ions in the solid phase can be shortened, the polarization of the battery cell can be reduced, heat generation can be reduced, and the high-temperature performance of the battery cell 1 can be improved.

[0181] In this application, the test method for the average particle size of primary particles is to use plasma to cut the positive electrode sheet along its thickness direction to obtain the cross-section of the positive electrode sheet, and observe it through a scanning electron microscope (SEM) at an appropriate magnification. Randomly select at least 50 primary particles. The average particle size of a single primary particle = (the longest diameter of a single particle + the shortest diameter of a single particle) / 2, and the average value of the selected primary particles is the average particle size of the primary particles.

[0182] According to some embodiments of the present application, referring to Figure 32 , the positive electrode film layer may include lithium-containing phosphate 221 and a lithium supplement agent 222. Based on the total mass of the positive electrode film layer, the mass ratio of the lithium supplement agent 222 may be 0.1% - 5%. For example, it can be 0.1%, 1%, 2%, 3%, 4%, 5%, etc., or it can be a range composed of any of the above values. Thus, lithium ions can be supplemented to the positive electrode film layer, making up for the lithium ion loss caused by the formation of the SEI film, improving the capacity of the battery cell 1, and improving the energy density of the battery cell 1.

[0183] According to some embodiments of the present application, the lithium supplement agent may include one or more of lithium nickel cobalt manganate, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganate, lithium tartrate, lithium citrate, lithium nickelate, and lithium ferrate. Thus, it can make up for the lithium consumption when the negative electrode forms the SEI film, and improve the first efficiency and energy density of the battery.

[0184] According to some embodiments of the present application, the positive electrode film layer further includes a conductive agent. Based on the total mass of the positive electrode film layer, the mass ratio of the conductive agent can be 0.1% - 1%. For example, it can be 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1%, etc., or it can be a range composed of any of the above values. Thereby, the electronic conductivity of the positive electrode film layer is improved.

[0185] According to some embodiments of the present application, the conductive agent includes carbon nanotubes. Thereby, the contact area between the conductive agent and the positive electrode active material is increased, the electronic conductivity of the positive electrode film layer is improved, the impedance of the electrode sheet is reduced, heat generation is reduced, and thus the high-temperature performance of the battery cell 1 is improved.

[0186] According to some embodiments of the present application, the thickness of the positive electrode current collector is 10 µm - 16 µm. For example, it can be 10 µm, 12 µm, 14 µm, 16 µm, etc., or it can be a range composed of any of the above values. Thereby, on the basis of reducing the occupied space inside the housing 11, the current-carrying capacity of the positive electrode current collector is improved.

[0187] In the present application, the thickness of the positive electrode current collector can be detected by using equipment and methods well-known in the art. For example, a micrometer is used to measure the thickness of the aluminum foil.

[0188] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil can be used. The composite current collector can include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0189] In some embodiments, the positive electrode sheet can be prepared in the following manner: dispersing the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode sheet can be obtained.

[0190] According to some embodiments of the present application, the electrode assembly further includes a negative electrode sheet. The negative electrode sheet includes a negative electrode current collector, and a negative electrode film layer is provided on at least one side of the negative electrode current collector. The compaction density of the negative electrode film layer corresponding to the battery cell at 100% SOC can be 1.15 g / cm 3 - 1.36 g / cm 3, for example, it can be 1.15 g / cm 3 , 1.2 g / cm 3 , 1.25 g / cm 3 , 1.3 g / cm 3 , 1.36 g / cm 3 etc., or it can be a range composed of any of the above values. According to some specific embodiments of the present application, the compaction density of the negative electrode film layer corresponding to the battery cell at 100% SOC can be 1.25 g / cm 3 -1.36 g / cm 3 . Thus, the energy density of the battery cell is improved.

[0191] The present application provides a method for testing the compaction density of the negative electrode film layer: charge at a constant current of 1 / 3C to 3.8V, charge at a constant voltage of 3.8V to 0.05C, disassemble the battery cell 1 to obtain the negative electrode plate. For example, take the negative electrode plate with single-sided coating (if it is a double-sided coated plate, the negative electrode film layer on one side can be wiped off first), punch it into small round pieces with an area of S2, weigh it, record it as M3, and measure its thickness H3. Then wipe off the negative electrode film layer of the weighed negative electrode plate, weigh the weight of the negative electrode current collector, record it as M2, and measure its thickness H2. The single-sided coating weight of the negative electrode film layer = (M3 - M2) / S2, the thickness of the negative electrode film layer = H3 - H2, and the compaction density of the negative electrode film layer = the single-sided coating weight of the negative electrode film layer / the thickness of the negative electrode film layer.

[0192] According to some embodiments of the present application, the single-sided coating weight of the negative electrode film layer can be 90 mg / 1540.25 mm 2 -170 mg / 1540.25 mm 2 , for example, it can be 90 mg / 1540.25 mm 2 , 110 mg / 1540.25 mm 2 , 130 mg / 1540.25 mm 2 , 150 mg / 1540.25 mm 2 , 170 mg / 1540.25 mm 2 etc., or it can be a range composed of any of the above values. According to some specific embodiments of the present application, the single-sided coating weight of the negative electrode film layer can be 110 mg / 1540.25 mm 2 -150 mg / 1540.25 mm 2 . Thus, the energy density of the battery cell is improved.

[0193] The present application provides a method for testing the coating weight of a negative electrode film layer: disassemble the negative electrode plate from a battery cell. For example, take a negative electrode plate with single-sided coating (if it is a double-sided coated electrode plate, the negative electrode film layer on one side can be wiped off first), punch it into small round pieces with an area of S2, weigh it, and record it as M3. Then wipe off the negative electrode film layer of the weighed negative electrode plate above, weigh the weight of the negative electrode current collector, and record it as M2. The single-sided coating weight of the negative electrode film layer = (M3 - M2) / S2.

[0194] According to some embodiments of the present application, the negative electrode film layer includes a negative electrode active material, and the charging gram capacity of the negative electrode active material at a 0.1C rate is 350 mAh / g - 480 mAh / g. For example, it can be 350 mAh / g, 370 mAh / g, 390 mAh / g, 410 mAh / g, 430 mAh / g, 450 mAh / g, 480 mAh / g, etc., or it can be a range composed of any of the above values. Thereby, the energy density of the battery cell is improved.

[0195] According to some embodiments of the present application, with reference to Figure 33 , the negative electrode film layer 31 includes a first negative electrode film layer 311 and a second negative electrode film layer 312. The first negative electrode film layer 311 is disposed on at least one side of the negative electrode current collector 30, and the second negative electrode film layer 312 is disposed on a side of the first negative electrode film layer 311 facing away from the negative electrode current collector 30. The first negative electrode film layer 311 includes first graphite particles, and the second negative electrode film layer 312 includes second graphite particles. The volume average particle diameter of the first graphite particles is greater than the volume average particle diameter of the second graphite particles. During the fast charging process, the overpotential of the second negative electrode film layer 312 is usually relatively high. By making the volume average particle diameter of the second graphite particles smaller, the solid-phase transmission path of lithium ions can be shortened, the diffusion rate of lithium ions can be increased, the fast charging performance can be improved, and at the same time, the problem of lithium metal deposition on the negative electrode surface can be improved.

[0196] According to some embodiments of the present application, the first graphite particles include natural graphite. Thereby, the compaction density of the negative electrode plate is improved.

[0197] According to some embodiments of the present application, the volume average particle diameter Dv50 of the first graphite particles is 7 µm - 18.5 µm. For example, it can be 7 µm, 11 µm, 13 µm, 15 µm, 17 µm, 18.5 µm, etc., or it can be a range composed of any of the above values.

[0198] According to some embodiments of the present application, the volume average particle size Dv50 of the second graphite particles is 7 µm - 14.3 µm. For example, it can be 7 µm, 9 µm, 11 µm, 13 µm, 14.3 µm, etc., or it can be a range composed of any of the above values. Thus, the volume average particle size of the second graphite particles is relatively small, which can shorten the solid-phase transmission path of lithium ions and improve the fast charging performance of the battery cell 1.

[0199] According to some embodiments of the present application, the first negative electrode film layer and the second negative electrode film layer each independently include a silicon-based material. Based on the total mass of the negative electrode film layer, the mass proportion of silicon element can be 0.3% - 10%. For example, it can be 0.3%, 1%, 3%, 5%, 7%, 9%, 10%, etc., or it can be a range composed of any of the above values. Thus, the capacity of the negative electrode active material is improved, and the energy density of the battery cell 1 is increased.

[0200] In the present application, the content of silicon element can be tested by inductively coupled plasma optical emission spectrometry ICP - OES.

[0201] According to some embodiments of the present application, the thickness of the negative electrode current collector is 4 µm - 8.5 µm. For example, it can be 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 8.5 µm, etc., or it can be a range composed of any of the above values. Thus, on the basis of reducing the occupation of the internal space of the housing 11, the current-carrying capacity of the negative electrode current collector is improved.

[0202] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, copper foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0203] In some embodiments, the negative electrode plate can be prepared in the following manner: the components for preparing the negative electrode plate, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode plate can be obtained.

[0204] According to some embodiments of the present application, the battery cell further includes an electrolyte, and the electrolyte includes a chain carboxylic ester. Based on the total mass of the electrolyte, the mass percentage of the chain carboxylic ester can be 5% - 60%, for example, it can be 5%, 10%, 20%, 30%, 40%, 50%, 60%, etc., or it can be a range composed of any of the above values. When the content of the chain carboxylic ester is within the above range, on the one hand, the viscosity of the electrolyte can be reduced, the internal resistance of the battery cell can be reduced, the migration rate of lithium ions can be increased, and the fast charging performance of the battery cell can be improved; on the other hand, the risk of gas generation of the electrolyte under high temperature conditions can be reduced, and the high temperature cycle life of the battery cell can be improved, thereby obtaining a battery cell with both high energy density, excellent fast charging performance and high temperature cycle life. According to some specific embodiments of the present application, the mass percentage of the chain carboxylic ester can be 8% - 30%.

[0205] In the present application, the test method for the content of the chain carboxylic ester is quantitative analysis of organic components by gas chromatography.

[0206] According to some embodiments of the present application, the chain carboxylic ester may include a compound represented by Formula I:

[0207] Formula I

[0208] Wherein, R1 includes one or more of a hydrogen atom, a C1 - C5 alkyl group, and a C1 - C5 haloalkyl group, and R2 includes one or more of a C1 - C5 alkyl group and a C1 - C5 haloalkyl group.

[0209] Thus, when the mass percentage of the chain carboxylic ester represented by Formula I is 5% - 60%, on the one hand, using the chain carboxylic ester with the above - mentioned content can improve the wetting ability of the electrolyte in the electrode film layer. Especially in a longer battery cell, it can improve the wetting uniformity of the electrolyte in the length direction of the electrode, improve the electron transfer ability of the active material. In addition, it can also increase the migration rate of lithium ions in the electrolyte, thereby improving the fast charging performance of the battery cell; on the other hand, an excessive content of carboxylic ester solvents will also increase the gas generation inside the battery cell, which is not conducive to the cycle of the battery at high temperature. Therefore, an appropriate amount of carboxylic ester solvents can also reduce the risk of gas generation of the electrolyte under high temperature conditions and improve the high temperature cycle life of the battery.

[0210] According to some embodiments of the present application, R1 includes one or more of a hydrogen atom, a C1 - C3 alkyl group, and a C1 - C3 haloalkyl group. For example, R1 may include one or more of a hydrogen atom, a methyl group, an ethyl group, a propyl group, a fluoromethyl group, a fluoroethyl group, and a fluoropropyl group.

[0211] According to some embodiments of the present application, R2 includes one or more of C1-C3 alkyl, C1-C3 haloalkyl. For example, R2 can be one or more of methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl.

[0212] According to some embodiments of the present application, the chain carboxylic acid ester may include Formula I-1, Formula I-2, Formula I-3, Formula I-4, Formula I-5, Formula I-6, Formula I-7, one or more of Formula I-8.

[0213] According to some embodiments of the present application, the charging time of the battery cell configured to charge from 10% SOC to 80% SOC is 5 min - 10.5 min. For example, it can be 5 min, 7 min, 9 min, 10.5 min, etc., or can be a range composed of any of the above values. Thereby, the fast charging performance of the battery cell is improved. According to some specific embodiments of the present application, the charging time of the battery cell configured to charge from 10% SOC to 80% SOC is 7 min - 10 min.

[0214] In some embodiments, the battery further includes a separator. The present application does not particularly limit the type of separator, and any well-known porous structure separator with good chemical stability and mechanical stability can be selected.

[0215] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0216] The second aspect of the present application provides a battery device, including the battery cell provided by the first aspect of the present application, and the battery device is at least one of a battery module, a battery pack, and an energy storage device.

[0217] The third aspect of the present application provides an electrical device, including the battery cell provided by the first aspect of the present application or the battery device provided by the second aspect of the present application, and the battery cell or the battery device is used to provide electrical energy.

[0218] The electrical equipment may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but not limited thereto.

[0219] As the electrical equipment, the battery device can be selected according to its usage requirements.

[0220] Figure 34 This is an example of electrical equipment. The electrical equipment is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the electrical equipment for the battery, a battery pack or a battery module can be adopted.

[0221] Another example of the device can be a mobile phone, a tablet computer, a laptop computer, etc. This device usually requires being thin and light, and a battery cell can be adopted as the power source.

[0222] To make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail in combination with the embodiments and the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and shall never be used as any limitation to the present application and its application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.

[0223] Embodiment 1

[0224] 1. Positive electrode tab

[0225] The positive electrode tab includes a positive electrode current collector aluminum foil, and positive electrode film layers are provided on two surfaces of the aluminum foil. The coating length of the positive electrode film layer is 585 mm, and the coating weight of the single-sided positive electrode film layer is 290 mg / 1540.25 mm 2 , in the state of 100% SOC, the compaction density is 2.65 g / cm 3 , based on the total mass of the single-sided positive electrode film layer, the positive electrode film layer includes a lithium iron phosphate material with a mass percentage of 95%, a lithium supplement agent lithium ferrite with 1.7%, a conductive agent carbon black with 1.1%, and a binder polyvinylidene fluoride (PVDF) with 2.2%. The volume particle size Dv10 of the lithium iron phosphate material is 0.35 μm, the volume average particle size Dv50 is 1.2 μm, the average particle size of the primary particles is 325 nm, and a carbon coating layer is provided on the surface of the lithium iron phosphate. Based on the total mass of the lithium iron phosphate positive electrode active material, the mass percentage of the carbon coating layer is 1.18%.

[0226] 2. Negative electrode sheet

[0227] The negative electrode sheet includes a negative current collector copper foil, and negative electrode film layers are provided on two surfaces of the copper foil. The negative electrode film layers include a first negative electrode film layer and a second negative electrode film layer. The mass ratio of artificial graphite conductive agent carbon black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) in the first negative electrode film layer is 96%: 1.1%: 1.4%: 1.5%. The volume average particle diameter Dv50 of the artificial graphite active material in the first negative electrode film layer is 15 μm. The mass ratio of artificial graphite, carbon black, SBR, and CMC-Na in the second negative electrode film layer is 96%: 1.1%: 1.4%: 1.5%. The volume average particle diameter Dv50 of the artificial graphite active material in the second negative electrode film layer is 11 μm. The tap density of the negative electrode film layer is 1.56 g / cm 3 , and the coating weight of the negative electrode film layer is 138 mg / 1540.25 mm 2 .

[0228] 3. Electrolyte

[0229] The electrolyte includes a solvent, an electrolyte salt, and an additive. The solvent includes ethyl acetate (EA), ethylene carbonate (EC), and dimethyl carbonate (DMC). The electrolyte salt includes lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide (LiFSI). The additive includes vinylene carbonate (VC), fluoroethylene carbonate (FEC), ethylene sulfite (ES), and lithium difluoro(oxalato)borate (LiDFOB). Based on the total mass of the electrolyte, the mass fraction of EA is 39%, the mass fraction of EC is 27.3%, the mass fraction of DMC is 11.7%, the mass fraction of VC is 5%, the mass fraction of FEC is 1%, the mass fraction of ES is 0.5%, the mass fraction of LiDFOB is 0.5%, the mass fraction of lithium hexafluorophosphate is 10.5%, and the mass fraction of LiFSI is 4.5%.

[0230] 4. Separator

[0231] Polypropylene film with a thickness of 12 μm.

[0232] 5. Battery cell

[0233] The battery cell includes a housing, a cover plate assembly, an electrode assembly, and an electrolyte. The cover plate assemblies are located at both ends in the length direction of the housing. The structure of one cover plate assembly refers to Figure 2 , and the structure of the other cover plate assembly refers to Figure 6, that is, one cover plate assembly includes a positive terminal, and the other cover plate assembly includes a negative terminal. The electrode assembly and the electrolyte are arranged in the accommodation cavity formed by the housing and the cover plate assembly. The electrode assembly is a laminated electrode assembly, which is made by laminating the above-mentioned positive electrode plate, separator, and negative electrode plate. Along the length direction of the electrode assembly, a positive electrode tab extends from one end, and a negative electrode tab extends from one end. The positive electrode tab is electrically connected to the positive terminal, and the negative electrode tab is electrically connected to the negative terminal.

[0234] The length of the housing of the battery cell is 630 mm, the width is 99.6 mm, and the thickness is 15.7 mm. The cross-sectional area of the first limiting part is 400 mm 2 , and the cross-sectional area of the terminal body is 90 mm 2 , and the cross-sectional area of the second limiting part is 172.86 mm 2 .

[0235] Performance test

[0236] 1. DCR

[0237] At 25 °C, the battery cell is charged at a constant current of 0.33C to 3.8V, then charged at a constant voltage to 0.05C, left standing for 30 min, and discharged at a constant current of 0.33C to 2.0V. At this time, the discharge capacity is A0, unit Ah. After standing for 30 min, it is charged at a constant current of 0.33C to 3.8V, charged at a constant voltage to 0.05C, and discharged at a constant current of 0.33C for 0.5A0. The SOC of the battery cell is adjusted, left standing for 120 min, and the voltage in the last 1 s is recorded as V0, unit V. Discharge at a constant current of 4A0 (unit A) for 30 s, and the end voltage of the discharge is V1, unit V. 30s DCR = (V0 - V1) / 4A0 × 1000, unit mΩ.

[0238] 2. High-temperature cycle life

[0239] At an ambient temperature of 45 °C, the battery cell is charged to 3.8V by Step charge, charged at a constant voltage to 0.05C, left standing for 30 min, and discharged at a constant current of 0.5C to 2.5V, then left standing for 30 min. This is one charge-discharge cycle. Repeat the above charge-discharge cycle until the capacity of the battery cell is 80% of the initial capacity, and the number of charge-discharge cycles obtained is the high-temperature cycle life of the battery cell.

[0240] The Step charge charging steps are as follows:

[0241] Charge from 0% SOC to 10% SOC at a constant current of 1C;

[0242] Charge from 10% SOC to 30% SOC at a constant current of 7.0C;

[0243] Charge from 30% SOC to 35% SOC at a constant current of 6.2C;

[0244] Charge from 35% SOC to 40% SOC at a constant current of 5.7C;

[0245] Charge from 40% SOC to 45% SOC at a constant current of 5.2C;

[0246] Charge from 45% SOC to 50% SOC at a constant current of 4.8C;

[0247] Charge from 50% SOC to 55% SOC at a constant current of 4.6C;

[0248] Charge from 55% SOC to 60% SOC at a constant current of 4.4C;

[0249] Charge from 60% SOC to 65% SOC at a constant current of 4.2C;

[0250] Charge from 65% SOC to 70% SOC at a constant current of 3.9C;

[0251] Charge from 70% SOC to 75% SOC at a constant current of 3.5C;

[0252] Charge from 75% SOC to 80% SOC at a constant current of 3.0C;

[0253] Charge from 80% SOC to 100% SOC at a constant current of 0.33C.

[0254] 3. Volume energy density

[0255] The test steps for the volume energy density (VED) of the battery cell are as follows:

[0256] Place the battery cells of the examples and comparative examples at 25°C, charge them at a constant current of 0.33C to 3.65V, then charge them at a constant voltage of 3.65V to 0.05C, and let them stand for 30 min; discharge them at a constant current of 0.33C to 2.0V, record the discharge capacity A0 at this time, unit: Ah, calculate the discharge platform voltage, unit: V; use a caliper to measure the length, width, and thickness of the battery cell, and calculate the volume V0 of the single battery cell, unit: L; the volume energy density VED of the battery cell = (A0 × discharge platform voltage (3.2V)) ÷ V0 ÷ 1000, unit: Wh / L.

[0257] In this application, the length of the battery cell = the coating length of the positive electrode film layer + 45 mm.

[0258] Example 2

[0259] The preparation method and structure of the battery cell are the same as those of Example 1, except that the cross-sectional area of the terminal body (i.e., the cross-sectional area of the terminal body along the direction perpendicular to the current flow direction) S is 100 mm2 。

[0260] Example 3

[0261] The preparation method and structure of the battery cell are the same as those in Example 1, except that the cross-sectional area S of the terminal body is 130 mm 2 。

[0262] Example 4

[0263] The preparation method and structure of the battery cell are the same as those in Example 1, except that the cross-sectional area S of the terminal body is 140 mm 2 。

[0264] Example 5

[0265] The preparation method and structure of the battery cell are the same as those in Example 1, except that the cross-sectional area S of the terminal body is 169 mm 2 。

[0266] Example 6

[0267] The preparation method and structure of the battery cell are the same as those in Example 1, except that the cross-sectional area S of the terminal body is 40 mm 2 。

[0268] Comparative Example 1

[0269] The preparation method and structure of the battery cell are the same as those in Example 1, except that the cross-sectional area S of the terminal body is 38 mm 2 , the coating length of the positive electrode film layer is 710 mm, and the length of the housing is 755 mm.

[0270] The detailed differences and test results of the battery cells in Examples 1 - 6 and Comparative Example 1 are shown in Table 1.

[0271] Table 1

[0272]

[0273] Example 7

[0274] The preparation method and structure of the battery cell are the same as those in Example 3, except that the coating length of the positive electrode film layer is 185 mm, and the length of the housing is 230 mm.

[0275] Example 8

[0276] The preparation method and structure of the battery cell are the same as those in Example 3, except that the coating length of the positive electrode film layer is 285 mm, and the length of the housing is 330 mm.

[0277] Example 9

[0278] The preparation method and structure of the battery cell are the same as those in Example 3, except that the coating length of the positive electrode film layer is 300 mm and the length of the housing is 345 mm.

[0279] Example 10

[0280] The preparation method and structure of the battery cell are the same as those in Example 3, except that the coating length of the positive electrode film layer is 470 mm and the length of the housing is 515 mm.

[0281] Example 11

[0282] The preparation method and structure of the battery cell are the same as those in Example 3, except that the coating length of the positive electrode film layer is 600 mm and the length of the housing is 645 mm.

[0283] Example 12

[0284] The preparation method and structure of the battery cell are the same as those in Example 3, except that the coating length of the positive electrode film layer is 620 mm and the length of the housing is 665 mm.

[0285] Comparative Example 2

[0286] The preparation method and structure of the battery cell are the same as those in Example 3, except that the coating length of the positive electrode film layer is 15 mm, the length of the housing is 60 mm, and the cross-sectional area of the terminal body is 169 mm 2 .

[0287] The detailed differences and test results of the battery cells in Examples 7 - 12 and Comparative Example 2 are shown in Table 2.

[0288] Table 2

[0289]

[0290] From the comparison between Examples 1 - 12 and Comparative Examples 1 and 2, it can be seen that when the ratio of the volume energy density VED of the battery cell to the minimum cross-sectional area S of the electrode terminal is between 2 Wh / L / mm 2 and 10 Wh / L / mm 2 , the battery cell can simultaneously have a high energy density, a low DCR, and a long cycle life. That is, by controlling the ratio of the volume energy density VED of the battery cell to S, a lithium phosphate-based battery cell with both a high energy density, excellent fast charging performance, and a long cycle life can be obtained.

[0291] As can be seen from Examples 1 - 6, when the cross-sectional area of the terminal body is smaller than the cross-sectional areas of both the first limiting portion and the second limiting portion, the cross-sectional area of the terminal body can affect the over-current capacity of the electrode terminal. By adjusting the cross-sectional area of the terminal body and controlling the ratio of the volume energy density VED to S of the battery cell, the DCR of the battery cell can be reduced, the cycle life of the battery cell can be improved, and thus a battery cell with both high energy density, excellent fast charging performance, and long cycle life can be obtained.

[0292] As can be seen from Comparative Example 2, although it has a low DCR and excellent cycle performance, due to the too short coating length of the positive electrode film layer, the energy density is too low.

[0293] As can be seen by comparing Example 3, Examples 7 - 12 with Comparative Example 2, when the coating length of the positive electrode film layer is different, the volume energy density of the battery cell is different. By matching the electrode terminal with an appropriate minimum cross-sectional area S, the DCR of the battery cell can be reduced, the cycle life of the battery cell can be improved, and thus a battery cell with both high energy density, excellent fast charging performance, and long cycle life can be obtained.

[0294] Example 13

[0295] The preparation method and structure of the battery cell are the same as those of Example 3, except that the cross-sectional area of the first limiting portion is 300 mm 2 .

[0296] Example 14

[0297] The preparation method and structure of the battery cell are the same as those of Example 3, except that the cross-sectional area of the first limiting portion is 500 mm 2 .

[0298] The detailed differences and test results of the battery cells in Example 3, Example 13, and Example 14 are shown in Table 3.

[0299] Table 3

[0300]

[0301] As can be seen from Table 3, by adjusting the cross-sectional area of the first limiting portion, the over-current capacity of the battery cell can be further improved, the DCR of the battery cell can be reduced, and thus a battery cell with excellent fast charging performance can be obtained.

[0302] Example 15

[0303] The preparation method and structure of the battery cell are the same as those of Example 3, except that the average primary particle size of the positive electrode active material (lithium iron phosphate material) is 200 nm, Dv10 is 0.33 μm, and Dv50 is 1.1 μm.

[0304] Example 16

[0305] The preparation method and structure of the battery cell are the same as those in Example 3, except that the average primary particle size of the positive electrode active material (lithium iron phosphate material) is 380 nm, Dv10 is 0.38 μm, and Dv50 is 1.3 μm.

[0306] The detailed differences and test results of the battery cells in Example 3, Example 15, and Example 16 are shown in Table 4.

[0307] Table 4

[0308]

[0309] It can be seen from Example 3, Example 15, and Example 16 that by controlling the particle size of the lithium iron phosphate material, the migration path of lithium ions in the solid phase can be shortened, the resistance of the battery cell can be reduced, and the high-temperature cycle life of the battery cell can be improved.

[0310] Example 17

[0311] The preparation method and structure of the battery cell are the same as those in Example 3, except that the volume average particle size Dv50 of the first graphite particles is 18.5 μm, and the tap density of the negative electrode film layer is 1.57 g / cm 3 .

[0312] Example 18

[0313] The preparation method and structure of the battery cell are the same as those in Example 3, except that the volume average particle size Dv50 of the first graphite particles is 13 μm, and the tap density of the negative electrode film layer is 1.54 g / cm 3 .

[0314] Example 19

[0315] The preparation method and structure of the battery cell are the same as those in Example 3, except that the volume average particle size Dv50 of the second graphite particles is 10 μm.

[0316] Example 20

[0317] The preparation method and structure of the battery cell are the same as those in Example 3, except that the volume average particle size Dv50 of the second graphite particles is 12.3 μm.

[0318] The detailed differences and test results of the battery cells in Example 3, Example 17 - Example 20 are shown in Table 5.

[0319] Table 5

[0320]

[0321] As can be seen from Example 3 and Examples 17 - 20, by adjusting the particle size of the graphite particles in the first negative electrode film layer, the energy density of the battery cell can be improved by improving the compaction of the negative electrode film layer. By adjusting the particle size of the graphite particles in the second negative electrode film layer, the DCR of the battery cell can be reduced and the fast charging performance of the battery cell can be improved.

[0322] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered within the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, include: A housing, comprising a first wall, wherein the housing has a receiving cavity; An electrode terminal, disposed on the first wall, wherein the minimum cross-sectional area of the electrode terminal is S; An electrode assembly is disposed in the accommodating cavity, wherein the electrode assembly comprises a positive electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector, wherein the positive electrode film layer comprises a lithium-containing phosphate; Among them, the ratio of the volumetric energy density VED of the battery cell to S is 2 Wh / L / mm 2 to 10 Wh / L / mm 2 .

2. The battery cell according to claim 1, wherein The ratio of the volume energy density VED of the battery cell to S is 2 Wh / L / mm 2 to 3.5 Wh / L / mm 2 .

3. The battery cell according to claim 1, characterized in that, The volume energy density VED of the battery cell satisfies: 350Wh / L≤VED≤430Wh / L.

4. The battery cell according to claim 1, wherein, The minimum cross-sectional area S of the electrode terminal satisfies: 40mm 2 ≤ S ≤ 800mm 2 .

5. The battery cell according to claim 1, characterized in that, The battery cell includes a cover plate assembly, which forms the first wall. The cover plate assembly includes a cover plate and the electrode terminal. The cover plate is provided with a through hole. The electrode terminal includes a terminal body, a first limiting portion and a second limiting portion. The terminal body passes through the through hole and connects the first limiting portion and the second limiting portion. The first limiting portion is located on a side of the cover plate facing the accommodating cavity, and the second limiting portion is located on a side of the cover plate away from the accommodating cavity.

6. The battery cell according to claim 5, characterized in that, The cross-sectional area of the second limiting portion is 300 mm 2 to 700 mm 2 .

7. The battery cell according to claim 5 or 6, characterized in that, The cross-sectional area of the first limiting portion is 200 mm 2 to 800 mm 2 .

8. The battery cell according to claim 5, wherein The cross section of the terminal body is a rounded rectangle.

9. The battery cell according to claim 8, wherein, The cross-sectional area of the terminal body is 40 mm 2 to 240 mm 2 .

10. The battery cell according to claim 1, characterized in that, Along the length direction of the positive electrode plate, the coating length of the positive electrode film layer is 200mm-700mm.

11. The battery cell according to claim 1, characterized in that, The single-sided coating weight of the positive electrode film layer is 200 mg / 1540.25 mm 2 -340 mg / 1540.25 mm 2 .

12. The battery cell according to claim 1, wherein, The single-sided coating weight of the positive electrode film layer is 240 mg / 1540.25 mm 2 -300 mg / 1540.25 mm 2 .

13. The battery cell according to claim 1, wherein, The tap density of the positive electrode film layer corresponding to the battery cell at 100% SOC is 2.5 g / cm 3 -2.8 g / cm 3 .

14. The battery cell according to claim 5, characterized in that, The cap plate assemblies are disposed at both ends of the housing, and each of the cap plate assemblies includes at least two electrode terminals.

15. The battery cell according to claim 5, characterized in that, The cap plate assemblies are arranged at two ends of the shell, and each of the cap plate assemblies includes at least two electrode terminals, and the polarities of the two electrode terminals are opposite.

16. The battery cell according to claim 5, wherein, The cover plate assemblies are arranged at both ends of the shell, and each of the cover plate assemblies includes at least two electrode terminals, the two electrode terminals have opposite polarities, and the electrode terminals of the same polarity on the two cover plate assemblies are staggered along the length direction of the battery cell.

17. The battery cell according to claim 16, characterized in that, The electrode terminals of the same polarity are arranged diagonally along the length direction of the battery cell.

18. The battery cell according to claim 1, wherein, The electrode assembly also includes a negative electrode sheet. The positive electrode sheet and the negative electrode sheet are stacked, each layer of the positive electrode sheet is provided with a positive electrode tab, and each layer of the negative electrode sheet is provided with a negative electrode tab.

19. The battery cell according to claim 18, wherein, The positive electrode tab extends along the length direction of the positive electrode sheet or along the width direction thereof; and / or The negative electrode tab extends along the length direction of the negative electrode sheet or along the width direction thereof.

20. The battery cell according to claim 1, characterized in that, The charging gram capacity of the lithium-containing phosphate at a rate of 0.1C is 150 mAh / g-170 mAh / g.

21. The battery cell according to claim 1, wherein The lithium-containing phosphate includes a compound shown in Formula I: Li x1 A y1 Me a M b P 1-c X c Y z Formula I Among them, 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, and 0.9 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a ≤ 1.5, 0 ≤ b ≤ 0.5, and 0.9 ≤ a + b ≤ 1.5, 0 ≤ c ≤ 0.5, 3 ≤ z ≤ 5, A includes one or more of Na, K, and Mg, Me includes one or more of Mn, Fe, Co, and Ni, M includes one or more of B, Mg, Al, P, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce, X includes one or more of S, Si, Cl, B, C, and N, and Y includes one or two of O and F.

22. The battery cell according to claim 1, characterized in that, The lithium-containing phosphate includes lithium iron phosphate material.

23. The battery cell according to claim 1, characterized in that, The lithium-containing phosphate is granular, and the volume average particle size Dv50 of the lithium-containing phosphate is 1 µm - 2 µm.

24. The battery cell according to claim 1, wherein, The volume particle size Dv10 of the lithium-containing phosphate is 0.4 µm - 0.7 µm.

25. The battery cell according to claim 1, characterized in that, The lithium-containing phosphate includes secondary particles, and the average particle size of the primary particles in the secondary particles is 200 nm - 500 nm.

26. The battery cell according to claim 1, characterized in that, The positive electrode film layer further includes a lithium supplement agent, and based on the total mass of the positive electrode film layer, the mass ratio of the lithium supplement agent is 0.1% - 5%.

27. The battery cell according to claim 26, wherein The lithium supplement agent includes one or more of lithium nickel cobalt manganate, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganate, lithium tartrate, lithium citrate, lithium nickelate, and lithium ferrate.

28. The battery cell according to claim 1, characterized in that, The positive electrode film layer further includes a conductive agent, and based on the total mass of the positive electrode film layer, the mass ratio of the conductive agent is 0.1% - 1%.

29. The battery cell according to claim 28, wherein The conductive agent includes carbon nanotubes.

30. The battery cell according to claim 1, characterized in that, The thickness of the positive electrode current collector is 10 µm - 16 µm.

31. The battery cell according to claim 1, wherein The electrode assembly further includes a negative electrode tab, the negative electrode tab includes a negative electrode current collector, and at least one side of the negative electrode current collector is provided with a negative electrode film layer, and the single-sided coating weight of the negative electrode film layer is 90 mg / 1540.25 mm 2 -170 mg / 1540.25 mm 2 .

32. The battery cell according to claim 31, wherein, The single-sided coating weight of the negative electrode film layer is 110 mg / 1540.25 mm 2 -150 mg / 1540.25 mm 2 .

33. The battery cell according to claim 31, wherein, The compaction density of the negative electrode film layer corresponding to the battery cell at 100% SOC is 1.15 g / cm 3 - 1.36 g / cm 3 .

34. The battery cell according to claim 31, wherein, The compaction density of the negative electrode film layer corresponding to the battery cell at 100% SOC is 1.25 g / cm 3 -1.36 g / cm 3 .

35. The battery cell according to claim 31, wherein, The negative electrode film layer includes a negative electrode active material, and the charging specific capacity of the negative electrode active material at a 0.1C rate is 350 mAh / g - 480 mAh / g.

36. The battery cell according to claim 31, wherein, The negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer. The first negative electrode is disposed on at least one side of the negative electrode current collector, and the second negative electrode film layer is disposed on a side of the first negative electrode film layer away from the negative electrode current collector. The first negative electrode film layer includes first graphite particles, and the second negative electrode film layer includes second graphite particles. The volume average particle size of the first graphite particles is greater than the volume average particle size of the second graphite particles.

37. The battery cell according to claim 36, wherein The first graphite particles include natural graphite.

38. The battery cell according to claim 36, wherein, The volume average particle size Dv50 of the first graphite particles is 7 µm - 18.5 µm; and / or The volume average particle size Dv50 of the second graphite particles is 7 µm - 14.3 µm.

39. The battery cell according to claim 36, wherein, The first negative electrode film layer and / or the second negative electrode film layer includes a silicon-based material, and based on the total mass of the negative electrode film layer, the mass ratio of silicon element is 0.3% - 10%.

40. The battery cell according to claim 31, wherein, The thickness of the negative electrode current collector is 4 µm - 8.5 µm.

41. The battery cell according to claim 1, characterized in that, It further includes an electrolyte, and the electrolyte includes a chain carboxylic acid ester. Based on the total mass of the electrolyte, the mass ratio of the chain carboxylic acid ester is 5% - 60%.

42. The battery cell according to claim 41, wherein Based on the total mass of the electrolyte, the mass proportion of the chain carboxylic acid ester is 8% - 30%.

43. The battery cell according to claim 1, characterized in that, The charging time for the battery cell to be configured to charge from 10% SOC to 80% SOC is 5 min - 10.5 min.

44. The battery cell according to claim 1, wherein, The charging time for the battery cell to be configured to charge from 10% SOC to 80% SOC is 7 min - 10 min.

45. A battery device, characterized in that, Including the battery cell described in any one of claims 1 - 44, the battery device is at least one of a battery module, a battery pack, and an energy storage device.

46. An electrical device, characterized in that, Including the battery cell described in any one of claims 1 - 44 or the battery device described in claim 45, the battery cell or the battery device is used to provide electrical energy.

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