Battery cells, battery devices, and electrical equipment

Abstract

The present application proposes a battery cell, a battery device, and an electrical device. The battery cell includes a positive electrode plate, the positive electrode plate includes a positive electrode film layer, the positive electrode film layer includes a lithium-containing phosphate and a lithium-supplementing additive, the lithium-supplementing additive includes at least one of an Fe oxide or a Ni oxide; a negative electrode plate; and an electrolyte, the electrolyte including a chain carboxylate, the electrolyte having a conductivity of 10mS / cm-18mS / cm at room temperature. Thus, by increasing the conductivity of the electrolyte, the fast-charging performance of the battery cell is improved. At the same time, by adding at least one of an Fe oxide or a Ni oxide to the positive electrode film layer, the stability of the negative electrode electrolyte interface film (SEI film) is improved, the gas production of the battery cell is reduced, and while improving the fast-charging performance of the battery cell, the high-temperature cycle life of the battery cell is also improved.

Description

[0001] This application claims priority to PCT international application PCT / CN2025 / 071092, entitled “Battery Cell, Battery Device, and Electrical Equipment,” filed on January 7, 2025, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of batteries, and in particular, to battery cells, battery devices, and electrical equipment. Background Art

[0003] Batteries are used not only in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. Charging batteries at high rates can generate significant heat, which can affect their long-term performance. Summary of the Invention

[0004] The first aspect of the present application provides a battery cell, comprising a positive electrode plate, the positive electrode plate comprising 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 comprising a lithium-containing phosphate and a lithium-supplementing additive, the lithium-supplementing additive comprising at least one of an Fe oxide or a Ni oxide; a negative electrode plate comprising a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector, the negative electrode film layer comprising graphite; and an electrolyte comprising a chain carboxylate, the electrolyte having a conductivity of 10 mS / cm to 18 mS / cm at room temperature. Thus, by improving the conductivity of the electrolyte, the fast-charging performance of the battery cell is improved. Simultaneously, by adding at least one of an Fe oxide or a Ni oxide to the positive electrode film layer, the stability of the negative electrolyte interface film (SEI film) is improved, gas generation of the battery cell is reduced, and the high-temperature cycle life of the battery cell is increased while improving the fast-charging performance of the battery cell.

[0005] According to some embodiments of the present application, the Fe oxide or the Ni oxide includes lithium and serves as a first lithium-replenishing additive to replenish lithium ions in the battery cell. Thus, while replenishing lithium, the first lithium-replenishing additive can also release oxygen to participate in the formation of the SEI film, improving the negative electrode interface impedance and increasing the cycle life and energy density of the battery cell.

[0006] According to some embodiments of the present application, the first lithium supplement additive includes at least one of lithium nickelate and lithium ferrite, thereby improving the cycle life of the battery cell.

[0007] According to some embodiments of the present application, the first lithium supplement additive includes Li e M1f O g , where 1≤e≤6, 1≤f≤6, 2≤g≤12, and M1 includes one or more of Ni, Co, Mn, and Fe. This provides additional lithium during the initial charge and participates in the formation of the SEI film, thereby improving the high-temperature cycle life of the battery cell.

[0008] According to some embodiments of the present application, the first lithium supplement additive includes Li2NiO2 and / or Li5FeO4, thereby improving the lithium supplement effect, improving the stability of the negative electrode SEI film, and increasing the high-temperature cycle life of the battery cell.

[0009] According to some embodiments of the present application, the first lithium supplement additive includes Li n NiO m and / or Li p FeO q , where 0≤n≤2, 0<m≤2, 0<p≤5, and 0<q≤4. That is, after the first lithium replenishing additive decomposes, it will transform into a partially delithiated state. The released lithium ions can be used to replenish lithium, and the released oxygen-containing species can participate in the formation of the SEI film, thereby improving the high-temperature cycle life of the battery cell.

[0010] According to some embodiments of the present application, the first lithium supplement additive includes NiO m and / or Li p FeO q , where 0 < m ≤ 2, 0 < p ≤ 1, and 0 < q ≤ 2. That is, after the first lithium replenishing additive decomposes, it will transform into a completely delithiated state. The released lithium ions can be used to replenish lithium, and the released oxygen-containing species can participate in the formation of the SEI film, thereby improving the high-temperature cycle life of the battery cell.

[0011] According to some embodiments of the present application, at least a portion of the surface of the first lithium-supplementing additive is provided with a coating layer, wherein the coating layer includes one or more of the elements C, Al, Zr, P, and S. This improves the air stability of the first lithium-supplementing additive and simultaneously improves the ion conductivity of the first lithium-supplementing additive.

[0012] According to some embodiments of the present application, the coating layer includes carbon material, aluminum oxide, zirconium oxide,

[0013] One or more of lithium phosphide and lithium sulfide. Thus, the air stability of the first lithium supplement additive is improved, and at the same time, the ion conductivity of the first lithium supplement additive is improved.

[0014] According to some embodiments of the present application, the first lithium supplement additive further includes a doping element, and the doping element includes one or more of Al, Zr, and B. Thus, the decomposition voltage of the first lithium supplement additive is reduced, and the lithium supplement effect is improved.

[0015] According to some embodiments of the present application, based on the total mass of the first lithium supplementing additive, the contents of Al, Zr, and B in the first lithium supplementing additive are independently 50 ppm to 1000 ppm, thereby reducing the decomposition voltage of the first lithium supplementing additive and improving the lithium supplementation effect.

[0016] According to some embodiments of the present application, the lithium-supplementing additive further includes a second lithium-supplementing additive, and the second lithium-supplementing additive includes one or more of lithium nickel cobalt manganese oxide, lithium phosphate, dilithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium metamanganate, lithium tartrate, and trilithium citrate. This improves the cycle life of the battery cells.

[0017] According to some embodiments of the present application, the total mass of the first lithium replenishing additive and the second lithium replenishing additive accounts for 0.1%-5% of the total mass of the positive electrode film layer, thereby improving the lithium replenishing effect.

[0018] According to some embodiments of the present application, the lithium-containing phosphate includes a compound shown in Formula I:

[0019]

[0020] Wherein, 0.5≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤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, M2 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. Thus, the safety performance and cycle life of the battery cell are improved.

[0021] According to some embodiments of the present application, the lithium-containing phosphate includes lithium iron phosphate material, thereby improving the safety performance and cycle life of the battery cell.

[0022] According to some embodiments of the present application, the lithium-containing phosphate is in granular form, and the volume average particle size Dv50 of the lithium-containing phosphate is 1µm-2µm. This shortens the migration path of lithium ions in the solid phase, reduces polarization of the battery cell, and reduces heat generation of the battery cell.

[0023] According to some embodiments of the present application, the volume particle size Dv10 of the lithium-containing phosphate is 0.4µm-0.7µm, thereby shortening the migration path of lithium ions in the solid phase, reducing the polarization of the battery cell, and reducing the heat generation of the battery cell.

[0024] According to some embodiments of the present application, the lithium-containing phosphate includes secondary particles, wherein the average particle size of the primary particles in the secondary particles is 200 nm to 500 nm. This shortens the migration path of lithium ions in the solid phase, reduces polarization of the battery cell, and reduces heat generation of the battery cell.

[0025] According to some embodiments of the present application, the mass proportion of the chain carboxylic acid ester is 5%-60%, and optionally 8%-30%, based on the total mass of the electrolyte. This reduces the viscosity of the electrolyte, lowers the internal resistance of the battery cell, and improves the fast charging performance of the battery cell.

[0026] According to some embodiments of the present application, the viscosity of the electrolyte at room temperature is 1.5 mPa·s-5.5 mPa·s.

[0027] According to some embodiments of the present application, the density of the electrolyte at room temperature is 1.05 g / mL-1.35 g / mL.

[0028] Therefore, by making the viscosity and density of the electrolyte within the above ranges, the migration rate of lithium ions in the electrolyte is increased, the internal resistance of the battery cell is reduced, and the fast charging performance of the battery cell is improved.

[0029] According to some embodiments of the present application, the chain carboxylate includes a compound represented by Formula II:

[0030] Formula II,

[0031] R1 comprises one or more of a hydrogen atom, a C1-C5 alkyl group, or a C1-C5 haloalkyl group, and R2 comprises one or more of a C1-C5 alkyl group or a C1-C5 haloalkyl group. As a result, these chain carboxylates have a relatively low molecular weight, which can improve the conductivity of the electrolyte and enhance the fast-charging performance of the battery cells.

[0032] According to some embodiments of the present application, R1 includes one or more of a hydrogen atom, a C1-C3 alkyl group, or a C1-C3 haloalkyl group; and / or R2 includes one or more of a C1-C3 alkyl group or a C1-C3 haloalkyl group. As a result, the aforementioned chain carboxylate esters have a relatively low molecular weight, which can improve the conductivity of the electrolyte and enhance the fast-charging performance of the battery cell.

[0033] According to some embodiments of the present application, the chain carboxylate comprises Formula II-1, Formula II-2, Formula II-3, Formula II-4, Formula II-5, Formula II-6, Formula II-7, One or more of formula II-8.

[0034] Therefore, the aforementioned chain carboxylic acid esters have a relatively small molecular weight, which can increase the conductivity of the electrolyte and improve the fast-charging performance of the battery cell.

[0035] 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 -340mg / 1540.25mm 2 , optional 240mg / 1540.25mm 2 -300mg / 1540.25mm 2 This increases the energy density of the battery cell.

[0036] According to some embodiments of the present application, the lithium-containing phosphate has a charge capacity of 150 mAh / g to 170 mAh / g at a charge rate of 0.1 C, thereby increasing the energy density of the battery cell.

[0037] According to some embodiments of the present application, the compaction density of the positive electrode film corresponding to the battery cell at 100% SOC is 2.5 g / cm 3 -2.8g / cm 3 This increases the energy density of the battery cell.

[0038] According to some embodiments of the present application, the electrode assembly further comprises a negative electrode sheet, wherein 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. This improves current transmission efficiency, reduces the resistance of the battery cells, and enhances the rate performance of the battery.

[0039] According to some embodiments of the present application, the battery cell further includes: a housing and a cover plate assembly, wherein the housing and the cover plate assembly define a storage cavity; the cover plate assembly is disposed at at least one end of the housing; the cover plate assembly includes a cover plate and an 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 extends 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 storage cavity, and the second limiting portion is located on the side of the cover plate facing away from the storage cavity. This improves the structural stability of the electrode terminal, reduces the risk of the electrode terminal falling off the through hole, and improves the cycle life of the battery cell.

[0040] According to some embodiments of the present application, the cover plate assemblies are disposed at both ends of the housing, and each of the cover 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.

[0041] 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 electrode terminals having opposite polarities. The electrode terminals of the same polarity on the two cover plate assemblies are staggered along the length of the battery cell. This reduces wiring during battery assembly and reduces assembly difficulty.

[0042] According to some embodiments of the present application, the electrode terminals of the same polarity are arranged diagonally along the length direction of the battery cell, thereby reducing wiring during battery assembly and lowering assembly difficulty.

[0043] According to some embodiments of the present application, the positive electrode tab extends along the length or width of the positive electrode sheet; and / or the negative electrode tab extends along the length or width of the negative electrode sheet. This improves current transmission efficiency, reduces battery cell resistance, and enhances battery rate performance.

[0044] According to some embodiments of the present application, the square cross-section of the terminal body is a rounded rectangle along a direction perpendicular to the thickness of the cover plate, thereby improving the current carrying capacity of the electrode terminal when the cover plate area is small.

[0045] According to some embodiments of the present application, the battery cell is configured to charge from 10% SOC to 80% SOC in a time range of 5 min to 10.5 min, or optionally 7 min to 10 min, thereby improving the fast charging performance of the battery cell.

[0046] A second aspect of the present application provides a battery device, comprising the battery cell provided in the first aspect of the present application, wherein the battery device is at least one of a battery module, a battery pack, and an energy storage device.

[0047] A third aspect of the present application provides an electrical device, comprising the battery cell provided in the first aspect of the present application or the battery device provided in the second aspect of the present application, wherein the battery cell or the battery device is used to provide electrical energy.

[0048] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0050] Figure 1 It is a cross-sectional schematic diagram of a positive electrode sheet in one embodiment of the present application. Figure 2 It is a schematic structural diagram of a shell according to one embodiment of the present application.

[0051] Figure 3 It is a structural schematic diagram of a cover assembly according to one embodiment of the present application.

[0052] Figure 4 yes Figure 3 Exploded view of the cover assembly in Figure 1.

[0053] Figure 5 yes Figure 4 A structural schematic diagram of the cover assembly from another perspective.

[0054] Figure 6 yes Figure 5 Schematic diagram of the cross section of the cover assembly along the AA' direction.

[0055] Figure 7 It is a structural schematic diagram of another cover assembly according to one embodiment of the present application.

[0056] Figure 8 yes Figure 7 Exploded view of the cover assembly in Figure 1.

[0057] Figure 9 yes Figure 7 A structural schematic diagram of the cover assembly from another perspective.

[0058] Figure 10 yes Figure 9Schematic diagram of the cross section of the cover assembly along the BB' direction.

[0059] Figure 11 It is a schematic structural diagram of a battery cell according to one embodiment of the present application.

[0060] Figure 12 It is a structural schematic diagram of a cover assembly according to another embodiment of the present application.

[0061] Figure 13 yes Figure 12 Exploded view of the cover assembly in Figure 1.

[0062] Figure 14 yes Figure 12 A structural schematic diagram of the cover assembly from another perspective.

[0063] Figure 15 yes Figure 14 Schematic cross-sectional view of the cover assembly along the CC' direction.

[0064] Figure 16 It is a structural schematic diagram of another cover assembly according to another embodiment of the present application.

[0065] Figure 17 yes Figure 16 Exploded view of the cover assembly in Figure 1.

[0066] Figure 18 yes Figure 16 A structural schematic diagram of the cover assembly from another perspective.

[0067] Figure 19 yes Figure 18 Schematic diagram of the cross section of the cover assembly along the DD' direction.

[0068] Figure 20 It is a schematic structural diagram of an electrode assembly according to one embodiment of the present application.

[0069] Figure 21 It is a schematic structural diagram of an electrode assembly according to another embodiment of the present application.

[0070] Figure 22 It is a schematic structural diagram of an electrode assembly according to one embodiment of the present application.

[0071] Figure 23 It is a schematic structural diagram of the positive electrode sheet according to one embodiment of the present application.

[0072] Figure 24 This is a schematic structural diagram of a positive electrode sheet according to another embodiment of the present application.

[0073] Figure 25 This is a schematic structural diagram of a positive electrode sheet according to another embodiment of the present application.

[0074] Figure 26 This is a schematic structural diagram of a positive electrode sheet according to another embodiment of the present application.

[0075] Figure 27 It is a schematic structural diagram of the negative electrode sheet according to one embodiment of the present application.

[0076] Figure 28 This is a schematic structural diagram of a negative electrode sheet according to another embodiment of the present application.

[0077] Figure 29 This is a schematic structural diagram of a negative electrode sheet according to another embodiment of the present application.

[0078] Figure 30 This is a schematic structural diagram of a negative electrode sheet according to another embodiment of the present application.

[0079] Figure 31 It is a schematic structural diagram of the negative electrode sheet according to one embodiment of the present application.

[0080] Figure 32 It is a schematic diagram of an electrical device of the present application.

[0081] Description 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 portion; 1223. Second limiting portion; 1224. Terminal body; 1225. Riveted block; 123. First insulating member; 1230. Through hole; 124. Sealing member; 125. Positioning member; 126. Second insulating member; 10. Electrode assembly; 2. Positive electrode sheet; 221. Lithium-containing phosphate; 222. Lithium supplement additive; 23. Positive electrode tab; 231. First positive electrode tab; 232. Second positive electrode tab; 3. Negative electrode sheet; 30. Negative current collector; 31. Negative electrode film layer; 311. First negative electrode film layer; 312. Second negative electrode film layer; 32. Negative electrode tab; 321. First negative electrode tab; 322. Second negative electrode tab; 4. Separator. DETAILED DESCRIPTION

[0083] The following embodiments of the technical solution of the present application are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only used as examples and are not intended to limit the scope of protection of the present application.

[0084] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may 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 a new technical solution.

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

[0087] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0088] Currently, market developments indicate that batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace applications. However, the battery cells used in related technologies cannot simultaneously meet the requirements of fast charging and long cycle times.

[0089] The present application aims to propose a battery cell with both excellent fast charging performance and high-temperature cycle life. The battery cell proposed in the present application comprises a positive electrode active material comprising a lithium-containing phosphate and a negative electrode active material comprising graphite. In order to further enhance the fast charging capability of the battery cell, a chain carboxylate is introduced into the electrolyte to enhance the wettability of the electrolyte in the positive electrode film layer comprising the lithium-containing phosphate and the negative electrode film layer comprising graphite, thereby contributing to enhancing the lithium ion transmission efficiency in the electrode film layer and enhancing the conductivity of the lithium ions in the electrolyte, thereby further enhancing the fast charging capability of the battery cell. However, as the conductivity of the electrolyte increases, the migration speed of the lithium ions in the electrolyte becomes faster, and the reaction rate at the phase interface increases accordingly. The violent reaction leads to uneven phase interface reaction, which makes the SEI film formed at the negative electrode unstable and continuously ruptures and reorganizes during the cycle, especially under high temperature conditions, further increasing the gas production of the battery cell and reducing the high-temperature cycle life of the battery cell. The present application discovered that by adding at least one of an Fe-containing oxide or a Ni-containing oxide to the positive electrode film layer, the oxygen-containing substances released by the decomposition during the battery cell cycle can participate in the film-forming reaction on the surface of the negative electrode active material, thereby improving the stability of the SEI film, improving the continuity of charge transfer, and reducing the increase in impedance caused by the instability of the SEI film, thereby improving the fast charging performance of the battery cell while improving the high-temperature cycle life of the battery cell.

[0090] The first aspect of the present application provides a battery cell, wherein the battery cell comprises a positive electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, Figure 1 The positive electrode film layer includes a lithium-containing phosphate 221 and a lithium supplement additive 222, and the lithium supplement additive 222 includes at least one of an Fe oxide or a Ni oxide; the negative electrode plate includes a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, and the negative electrode film layer includes graphite; the electrolyte includes a chain carboxylate, and the conductivity of the electrolyte at room temperature is 10mS / cm-18mS / cm.

[0091] Therefore, the battery cell proposed in this application improves the fast charging capability of the battery cell by introducing a chain carboxylate into the electrolyte. On this basis, at least one of an Fe-containing oxide or a Ni-containing oxide is added to the positive electrode film layer to improve the stability of the SEI film, reduce the continuous rupture and recombination of the SEI due to the excessively high conductivity of the electrolyte, and improve the high-temperature cycle life of the battery cell.

[0092] In the present application, the positive electrode sheet can be cut along its thickness direction by plasma to obtain a cross-section of the positive electrode sheet, and observed by a scanning electron microscope (SEM) at an appropriate magnification. The average particle size is 500μm-800nm ​​for lithium-containing phosphate, and the average particle size is 10μm-15μm for Fe-containing oxide or Ni-containing oxide.

[0093] As an example, the conductivity of the electrolyte at room temperature is 10 mS / cm, 12 mS / cm, 14 mS / cm, 16 mS / cm, 18 mS / cm, etc., or can be any range of the above values. This improves the ionic conductivity of the electrolyte and the rate performance of the battery cell.

[0094] In this application, after disassembling the battery cells to obtain the electrolyte, a conductivity meter is used. The conductivity of the electrolyte at room temperature can be tested with reference to HG-T 4067-2015.

[0095] According to some embodiments of the present application, the Fe oxide or the Ni oxide includes lithium and serves as a first lithium-replenishing additive to supplement the lithium ions in the battery cell. Specifically, the inclusion of lithium in the Fe oxide or the inclusion of lithium in the Ni oxide allows the first lithium-replenishing additive to act during the formation process or the cycling of the battery cell and release active lithium ions to compensate for the lithium ions consumed in forming the SEI film, thereby improving the cycle life and energy density of the battery cell.

[0096] According to some embodiments of the present application, the first lithium supplement additive includes at least one of lithium nickelate and lithium ferrite.

[0097] In some embodiments of the present application, the first lithium supplement additive may include Li e M1 f O g , wherein 1≤e≤6, 1≤f≤6, 2≤g≤12, and M1 may include one or more of Ni, Co, Mn, and Fe.

[0098] Exemplarily, the value of e can be 1, 2, 3, 4, 5 or 6, etc., or can be a range consisting of any of the above values. Optionally, the value of e can be 1<e≤6, such as 2≤e≤5.

[0099] The value of f can be 1, 2, 3, 4, 5 or 6, etc., or can be a range consisting of any of the above values.

[0100] The value of g can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, etc., or can be a range consisting of any of the above values. Optionally, the value of g can be 2≤g≤8.

[0101] Among them, Li e M1 f O g The charge capacity is 1 to 5 times that of the multi-element positive electrode active material, which can provide additional lithium during the first charge process. In addition, it is beneficial to pre-store additional lithium in the negative electrode to extend the battery life. e M1 f O g , which can achieve a good lithium replenishment effect. It is understandable that during the battery formation and use process, as the lithium replenishment process proceeds, the lithium in the first lithium replenishment additive will be partially or completely released, causing the first lithium replenishment additive to transform from an initial state to a partially or completely delithiated state. At this time, the situation of e≤1 and / or g≤2 will occur.

[0102] In some embodiments of the present application, the first lithium supplement additive may include but is not limited to Li2NiO2 and / or Li5FeO4. In the manufacturing process of the positive electrode sheet, Li2NiO2 and / or Li5FeO4 may be directly incorporated into the positive electrode active material layer.

[0103] Li2NiO2 can form LiNiO2 with lithium deintercalation ability after lithium removal. LiNiO2 can become Li 1-x NiO2, 0≤x≤1, can be restored to LiNiO2 in the lithium-intercalated state.

[0104] Li5FeO4 has a strong lithium replenishment capacity, and the LiFeO2 formed after delithiation does not cause obvious side reactions. Therefore, using Li2NiO2 and / or Li5FeO4 as a lithium replenisher can achieve a good capacity compensation effect.

[0105] Exemplarily, the lithium replenisher may be Li2NiO2, which can provide considerable lithium replenishment capacity simply by changing the valence of Ni atoms at a relatively low potential, without requiring oxygen atoms to change valence, thereby reducing the risk of the electrolyte being oxidized by oxygen free radicals.

[0106] In some embodiments of the present application, the first lithium supplement additive may include an initial state, a partially delithiated state, and a completely delithiated state. When the first lithium supplement additive changes from the initial state to the partially delithiated state and the completely delithiated state, the lithium supplement additive may include Li n NiO m and / or Li p FeO q , where 0≤n≤2, 0<m≤2, 0<p≤5, 0<q≤4.

[0107] For example, the value of n can be 0, 0.5, 1, 1.5 or 2, or can be a range consisting of any of the above values.

[0108] The value of m can be 0.5, 1, 1.5 or 2, etc., or can be a range consisting of any of the above values.

[0109] The value of p can be 0.5, 1, 2, 3, 4 or 5, etc., or can be a range consisting of any of the above values.

[0110] The value of q can be 1, 2, 3 or 4, etc., or can be a range consisting of any of the above values.

[0111] For example, taking the first lithium supplement additive of Li2NiO2 in its initial state as an example, when the lithium in Li2NiO2 is partially released, the first lithium supplement additive Li n NiO m The composition may include one or more components of 0<n<1, n=1, 1<n<2; when the lithium in Li2NiO2 is completely removed, the first lithium supplement additive Li n NiO m The composition may include NiO m .

[0112] Taking the first lithium supplement additive of Li5FeO4 in its initial state as an example, when the lithium in Li5FeO4 is partially released, the first lithium supplement additive Li p FeO q The composition may include one or more components of 1<p<2, 2≤p<3, 3≤p<4, 4≤p<5; when the lithium in Li5FeO4 is completely removed, the first lithium supplement additive Li p FeO q The composition may include LiFeO2. Under factors such as polarization, LiFeO2 may continue to remove lithium, and Li with p < 1 may appear. p FeO q component.

[0113] In some embodiments of the present application, when the first lithium supplement additive changes from an initial state to a completely delithiated state, the first lithium supplement additive may include NiO m and / or Li p FeO q , where 0<m≤2, 0<p≤1, 0<q≤2.

[0114] For example, the value of m can be 0.5, 1, 1.5 or 2, or can be a range consisting of any of the above values.

[0115] The value of p can be 0.2, 0.5, 0.8 or 1, etc., or can be a range consisting of any of the above values.

[0116] The value of q can be 0.2, 0.5, 1, 1.5 or 2, etc., or can be a range consisting of any of the above values.

[0117] For example, taking the lithium supplement agent whose initial state is Li2NiO2 and Li5FeO4 as an example, when the first lithium supplement additive is completely delithiated, the first lithium supplement additive after decomposition may include but is not limited to NiO and / or LiFeO2, and the oxygen-containing substances released by the decomposition during the battery cell cycle can participate in the film-forming reaction on the surface of the negative electrode active material, thereby improving the stability of the SEI film, improving the continuity of charge transfer, and reducing the increase in impedance caused by the instability of the SEI film, thereby improving the fast charging performance of the battery cell while improving the high-temperature cycle life of the battery cell.

[0118] In some embodiments of the present application, at least part of the surface of the first lithium supplement additive may be provided with a coating layer, and the coating layer may include one or more of the elements C, Al, Zr, P, and S. The types of elements in the coating layer of the lithium supplement additive may be qualitatively analyzed in combination with characterization methods such as EDS energy spectrum analysis. The air stability of lithium supplement agents is generally poor. Taking Li2NiO2 as an example, it has a strong alkalinity and is easy to react with water and CO2. The formation of a coating layer on the surface of the lithium supplement additive can, on the one hand, improve its air stability and reduce the generation of lithium-containing impurities on the surface; on the other hand, it can also improve the ion conductivity of the lithium supplement additive, improve the transmission efficiency of lithium ions, and improve the kinetic performance, thereby further facilitating delithiation and improving lithium supplement capacity.

[0119] In some embodiments of the present application, the coating layer may include one or more of carbon materials, aluminum oxides, zirconium oxides, lithium phosphides, and lithium sulfides. The type of coating layer material can be determined by combining one or more analytical methods such as EDS energy spectrum analysis and X-ray diffraction. Among them, the conductivity of lithium supplement additives is relatively poor. Carbon materials, aluminum oxides, and zirconium oxides as coating layer materials are beneficial to improving the air stability of lithium supplement additives and reducing the formation of lithium-containing impurities on the surface. In addition, the use of carbon materials as coating layer materials is beneficial to improving the conductivity of the positive electrode plate; the use of fast ion conductors such as lithium phosphides or lithium sulfides (for example, lithium phosphate or lithium sulfate) as coating layer materials is beneficial to improving the lithium ion transfer rate and improving the kinetic performance, thereby further facilitating lithium de-lithiation and improving the lithium supplement capacity. This is beneficial to further improve the electrochemical performance of the battery.

[0120] In some embodiments of the present application, the first lithium supplement additive may further include a doping element, which may include one or more of Al, Zr, and B. Doping the first lithium supplement additive with one or more of Al, Zr, and B not only helps reduce the decomposition voltage of the lithium supplement additive and enhance its decomposition capacity, enabling it to provide greater capacity compensation, but also helps stabilize the crystal structure of the lithium supplement additive after decomposition, reduces transition metal dissolution and possible side reactions with the electrolyte, thereby further improving the battery's energy efficiency and cycle life.

[0121] In some embodiments of the present application, based on the total mass of the first lithium supplement additive, the content of Al element, Zr element, and B element in the first lithium supplement additive can be independently 50ppm-1000ppm, such as 50ppm, 200ppm, 500ppm, 800ppm or 1000ppm, etc.

[0122] According to some embodiments of the present application, the lithium supplement additive also includes a second lithium supplement additive, and the second lithium supplement additive includes one or more of lithium nickel cobalt manganese oxide, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium metamanganate, lithium tartrate, and trilithium citrate.

[0123] In the present application, by simultaneously adding the first lithium replenishing additive and the second lithium replenishing additive to the positive electrode film layer, both lithium replenishing additives can replenish lithium ions, make up for the irreversible lithium ion loss in the system, and increase the capacity of the battery. In addition, the first lithium replenishing additive can also release oxygen elements, participate in the formation of the SEI film, improve the stability of the SEI film, and increase the cycle life of the battery cell.

[0124] According to some embodiments of the present application, the total mass of the first and second lithium-supplementing additives can be 0.1%-5% based on the total mass of the positive electrode film layer, for example, 0.1%, 1%, 2%, 3%, 4%, 5%, or any range thereof. This improves the lithium replenishment effect, increases the capacity of the battery cell, and increases the cycle life and energy density of the battery cell.

[0125] In the present application, one or more conventional instruments and methods such as a scanning electron microscope, an EDS spectrometer, an X-ray diffractometer, and an inductively coupled plasma emission spectrometer can be combined to qualitatively analyze the positive electrode film layer to determine whether there is a lithium supplement additive in the positive electrode film layer and its type. For example, in the positive electrode active material layer, in addition to the different elemental compositions, the lithium supplement additive and the positive electrode active material particles usually also have differences in size and particle morphology. Moreover, the lithium supplement additive does not completely disappear after delithiation, but rather leaves residual elements and particle skeletons. The lithium supplement additive usually shrinks in volume after delithiation, so that a certain gap is formed between the residual particle skeleton and the surrounding area (reference Figure 1 As shown, Figure 1 This is a scanning electron micrograph of a cross-section of a positive electrode sheet in a battery cell according to another embodiment of the present application. It shows the microscopic morphology of a lithium-supplementing additive (e.g., lithium ferrite) with a coating layer after delithiation. During the later stages of delithiation, gaps form between the particle skeleton and the coating layer on the surface of the lithium-supplementing additive. Based on these differences, scanning electron microscopy testing can be used to quickly screen for possible locations of the lithium-supplementing additive in a cross-section of the positive electrode sheet along its thickness. Furthermore, EDS analysis can be used to distinguish between lithium-supplementing additive particles and positive electrode active material particles by elemental composition, and then to compare the size differences between the positive electrode active material particles and the lithium-supplementing additive particles. For another example, the surface roughness of positive electrode active material particles and lithium-supplementing additive particles is typically different. This difference can also be used to quickly screen for possible locations of the lithium-supplementing additive during scanning electron microscopy testing. For another example, lithium-supplementing additives are typically not completely delithiated after formation. By comparing the changes in diffraction peaks (e.g., peak position, peak intensity, etc.) in the XRD patterns of the positive electrode active material layer before and after charge and discharge, it can be determined in advance whether the positive electrode sheet contains a lithium-supplementing additive and what type of lithium-supplementing additive has been added. In addition, due to the difference in lithium content between the lithium-supplementing additive and the positive electrode active material itself, as well as the different lithium deintercalation efficiency during charging and discharging, the lithium content of the battery cell in the fully charged or fully discharged state is also different. For example, in the charged state, the lithium deintercalation efficiency of the lithium-supplementing additive in the positive electrode is usually lower than that of the positive electrode active material, which can be characterized and distinguished by FIB (focused ion beam) combined with SIMS (secondary ion mass spectrometry) testing; and in a charging and discharging process, the difference in lithium deintercalation efficiency between the lithium-supplementing additive and the positive electrode active material leads to obvious differences in the volume expansion between the material particles, which can be observed and characterized by in situ confocal microscopy.

[0126] According to some embodiments of the present application, the lithium-containing phosphate includes a compound shown in Formula I:

[0127] Li x A y Me a M2 b P 1-c Xc Y z Formula I,

[0128] Wherein, 0.5≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3, 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5, 0≤c≤0.5, and 3≤z≤5, A includes one or more of Na, K, and Mg, Me includes one or more of Mn, Fe, Co, and Ni, M2 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 both of O and F. Thus, the safety performance and cycle life of the battery cell are improved.

[0129] As an example, x may be 0.5, 0.7, 0.9, 1.1, 1.3, etc., or may be a range consisting of any of the above values.

[0130] As an example, y may be 0, 0.3, 0.6, 0.9, 1.1, 1.3, etc., or may be a range consisting of any of the above values.

[0131] As an example, a may be 0.9, 1.1, 1.3, 1.5, etc., or may be a range consisting of any of the above values.

[0132] As an example, b can be 0, 0.2, 0.4, 0.5, etc., or can be a range consisting of any of the above values.

[0133] As an example, c can be 0, 0.2, 0.4, 0.5, etc., or can be a range consisting of any of the above values.

[0134] As an example, z can be 3, 3.5, 4, 4.5, 5, etc., or can be a range consisting of any of the above values.

[0135] According to some embodiments of the present application, the lithium-containing phosphate includes lithium iron phosphate material, thereby improving the safety and cycle performance of the battery cell.

[0136] According to some embodiments of the present application, the lithium-containing phosphate is in a granular form, and the volume average particle size Dv50 of the lithium-containing phosphate is 1µm-2µm, for example, 1µm, 1.2µm, 1.4µm, 1.6µm, 1.8µm, 2µm, etc., or a range consisting of any of the above values. As a result, the volume average particle size of the lithium-containing phosphate with an olivine structure is small, which can shorten the migration path of lithium ions in the solid phase, reduce polarization of the battery cell, reduce heat generation, and improve the high-temperature cycling performance of the battery cell.

[0137] In this application, Dv50 refers to the particle size at which the cumulative volume distribution percentage reaches 50%, as measured, for example, using a laser particle size analyzer (Malvern Master Size 2000) in accordance with the standard GB / T 19077-2016 / ISO 13320:2009. The specific testing process is as follows: The cathode film powder is scraped off, calcined at high temperature in an air atmosphere, ground into a powder, and sieved. An appropriate amount of the sample to be tested (ensuring a light-blocking concentration of 8%-12%) is taken, deionized water is added, and ultrasonic dispersion is performed to ensure complete dispersion of the sample. The sample is then measured in accordance with the GB / T 19077-2016 / ISO 13320:2009 standard.

[0138] According to some embodiments of the present application, the volume particle size Dv10 of the lithium-containing phosphate is 0.4µm-0.7µm, for example, 0.4µm, 0.5µm, 0.6µm, 0.7µm, etc., or a range consisting of any of the above values. As a result, the volume particle size Dv10 of the olivine-structured lithium-containing phosphate is small, which can shorten the migration path of lithium ions in the solid phase, reduce polarization of the battery cell, reduce heat generation, and improve the high-temperature cycling performance of the battery cell.

[0139] In this application, Dv10 refers to the particle size corresponding to the cumulative volume distribution percentage reaching 10%, as measured, for example, using a laser particle size analyzer (Malvern Master Size 2000) in accordance with the standard GB / T 19077-2016 / ISO 13320:2009. The specific testing process is as follows: scrape the positive electrode film powder, calcine it at high temperature in an air atmosphere, grind it into a powder, and after screening, take an appropriate amount of the sample to be tested (the sample concentration should ensure an 8%-12% light shielding), add deionized water, and ultrasonically disperse the sample to ensure complete dispersion. The sample is then measured according to the GB / T19077-2016 / ISO 13320:2009 standard.

[0140] 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 200nm-500nm, for example, 200nm, 300nm, 400nm, 500nm, etc., or a range consisting of any of the above values. This can shorten the migration path of lithium ions in the solid phase, reduce polarization of the battery cell, reduce heat generation, and improve the high-temperature performance of the battery cell.

[0141] 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 a cross-section of the positive electrode sheet, observe it under an appropriate magnification using a scanning electron microscope (SEM), and 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.

[0142] According to some embodiments of the present application, the battery cell further includes an electrolyte, and the electrolyte includes a chain carboxylate. Based on the total mass of the electrolyte, the mass proportion of the chain carboxylate can be 5%-60%, for example, 5%, 10%, 20%, 30%, 40%, 50%, 60%, etc., or can be a range composed of any of the above values. By making the content of the chain carboxylate 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 production of the electrolyte under high temperature conditions can be reduced, and the high temperature cycle life of the battery cell can be increased, thereby obtaining a battery cell with high energy density, excellent fast charging performance and high temperature cycle life. According to some specific embodiments of the present application, the mass proportion of the chain carboxylate can be 8%-30%.

[0143] In the present application, the content of the chain carboxylic acid ester is tested by quantitative analysis of organic components by gas chromatography.

[0144] According to some embodiments of the present application, the chain carboxylate may include a compound represented by Formula II:

[0145] Formula II,

[0146] 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.

[0147] Therefore, when the mass proportion of the chain carboxylic acid ester shown in Formula I is 5%-60%, on the one hand, the use of the chain carboxylic acid ester with the above-mentioned content can improve the wetting ability of the electrolyte in the electrode film layer, especially in longer battery cells, improve the wetting uniformity of the electrolyte in the length direction of the electrode, improve the electron transmission ability of the active material, and in addition, can also increase the lithium ion migration rate in the electrolyte, thereby improving the fast charging performance of the battery cell; on the other hand, too high a content of carboxylic acid ester solvents also increases the gas production inside the battery cell, which is not conducive to the cycle of the battery at high temperature. Therefore, an appropriate amount of carboxylic acid ester solvents can also reduce the risk of gas production of the electrolyte under high temperature conditions and improve the high temperature cycle life of the battery.

[0148] According to some embodiments of the present application, R1 includes one or more of a hydrogen atom, a C1-C3 alkyl group, or 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, or a fluoropropyl group. This improves the conductivity of the electrolyte.

[0149] According to some embodiments of the present application, R2 includes one or more of a C1-C3 alkyl group and a C1-C3 haloalkyl group. For example, R2 can be one or more of a methyl group, an ethyl group, a propyl group, a fluoromethyl group, a fluoroethyl group, and a fluoropropyl group. This improves the conductivity of the electrolyte.

[0150] According to some embodiments of the present application, the chain carboxylic acid ester may include Formula II-1, Formula II-2, Formula II-3, Formula II-4, Formula II-5, Formula II-6, Formula II-7, One or more of formula II-8. Therefore, the molecular weight of the above-mentioned chain carboxylic acid ester is relatively small, which can improve the conductivity of the electrolyte.

[0151] According to some embodiments of the present application, the viscosity of the electrolyte at room temperature may be 1.5 mPa·s to 5.5 mPa·s, for example, 1.5 mPa·s, 2.5 mPa·s, 3.5 mPa·s, 4.5 mPa·s, 5.5 mPa·s, etc., or may be within a range consisting of any of the foregoing values. This increases the migration rate of lithium ions in the electrolyte, reduces the internal resistance of the battery cell, and improves the fast charging performance of the battery cell.

[0152] In the present application, after disassembling the battery cells to obtain the electrolyte, the viscosity of the electrolyte is tested by a kinematic viscometer. The viscosity of the electrolyte at room temperature can be tested with reference to GB / T 10247-2008.

[0153] According to some embodiments of the present application, the density of the electrolyte at room temperature can be 1.05 g / mL-1.35 g / mL, for example, 1.05 g / mL, 1.15 g / mL, 1.25 g / mL, 1.35 g / mL, etc., or can be a range consisting of any of the above values. This increases the migration rate of lithium ions in the electrolyte, reduces the internal resistance of the battery cell, and improves the fast charging performance of the battery cell.

[0154] In this application, after disassembling the battery cell to obtain the electrolyte, the density of the electrolyte is tested using a liquid density meter. The density of the electrolyte at room temperature can be tested with reference to GB / T 2013-2010.

[0155] According to some embodiments of the present application, the single-sided coating weight of the positive electrode film layer can be 200 mg / 1540.25 mm 2 -340mg / 1540.25mm 2 , for example, it can be 200mg / 1540.25mm 2 、230mg / 1540.25mm 2 、260mg / 1540.25mm 2 、290mg / 1540.25mm 2 、320mg / 1540.25mm 2 、340mg / 1540.25mm 2 etc., or can be a range consisting of any of the above values. Thus, by making the coating weight of the positive electrode film layer within the above range, the energy density of the battery cell can be increased. 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 -300mg / 1540.25mm 2 .

[0156] This application provides a method for testing the coating weight of the positive electrode film layer: A battery cell is disassembled to remove the positive electrode sheet. For example, a single-sided coated positive electrode sheet (for double-sided coated sheets, the positive electrode film layer on one side can be wiped off first) is punched into small discs with an area of ​​S1. These discs are weighed and recorded as M1. The positive electrode film layer of the weighed positive electrode sheet is then 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.

[0157] According to some embodiments of the present application, the lithium-containing phosphate has a charge capacity of 150 mAh / g to 170 mAh / g at a charge rate of 0.1 C, thereby increasing the energy density of the battery cell.

[0158] 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 can be 2.5 g / cm 3 -2.8g / cm 3 , for example, it can be 2.5 g / cm 3 , 2.55g / cm 3 , 2.6g / cm 3 , 2.65g / cm 3 , 2.7g / cm 3 , 2.75g / cm 3 , 2.8g / cm 3 etc., or can be within a range consisting of any of the above values. Therefore, when the compaction density of the positive electrode film layer is within the above range, the positive electrode sheets are densely stacked, which is beneficial to improving the energy density of the battery cell. In addition, the contact resistance between particles is small, which can further reduce the internal resistance of the battery cell, reduce the heat generation of the battery cell, and improve the high-temperature performance of the battery cell.

[0159] The present application provides a method for testing the compaction density of the positive electrode film layer: charge to 3.8V at a constant current of 1 / 3C, charge to 0.05C at a constant voltage of 3.8V, disassemble the battery cell 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 a small disc 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 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.

[0160] According to some embodiments of the present application, reference Figure 2-Figure 6 The battery cell includes a shell 11 and a cover assembly 12. The cover assembly 12 is arranged at at least one end of the shell 11. The shell 11 and the cover assembly 12 define a receiving cavity.

[0161] Specifically, the cover plate assembly 12 may be disposed at at least one end of the housing 11 along its length direction, or the cover plate assembly 12 may be disposed at at least one end of the housing 11 along its width direction.

[0162] As an example, refer to Figure 2The cover plate assembly 12 can be provided at both ends of the housing 11 along its length direction; or the cover plate assembly 12 can be provided at both ends of the housing 11 along its width direction. Specifically, when the housing 11 has openings at both ends along its length direction, the cover plate assembly 12 can be provided at both ends of the housing 11 along its length direction and be adapted to cover the openings respectively; when the housing 11 has openings at both ends along its width direction, the cover plate assembly 12 can be provided at both ends of the housing 11 along its width direction and be adapted to cover the openings respectively, so as to isolate the internal environment of the battery cell from the external environment. The shape of the cover plate assembly 12 can be adapted to the shape of the housing 11 to match the housing 11.

[0163] In some embodiments, the cover plate assembly 12 can be arranged at both ends of the shell 11 along its length direction, that is, the cover plate assembly 12 is arranged on the smaller side of the shell 11, thereby saving space of the battery cell along the width direction, thereby accommodating wider pole pieces and improving the energy density of the battery cell.

[0164] According to some embodiments of the present application, the cover plate assembly includes a cover plate and an electrode terminal, a through hole is provided on the cover plate, and 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.

[0165] In some embodiments, the shell 11 is formed by bending and then welding, and the weld marks are integrated on the smaller side surfaces of the shell 11 extending along the length direction, which helps to reduce the problem of cracking in the welding area caused by expansion of the battery cell along the thickness direction and improve the reliability of the shell 11.

[0166] refer to Figure 3-Figure 6 The cap plate assembly 12 includes a first cap plate 1213 and an electrode terminal 1221 .

[0167] In some embodiments, reference Figure 4 The disassembly diagram of the cover plate assembly 12, the cover plate assembly 12 includes a first cover plate 1213, an electrode terminal 1221, a first insulating member 123, a sealing member 124, a second insulating member 126, a rivet block 1225, a positioning member 125, and is assembled into Figure 3 The cover plate assembly 12 is shown.

[0168] In some embodiments, Figure 6 yes Figure 5 A schematic cross-sectional view of the cover assembly 12 along the AA' direction, combined with Figure 4 and Figure 6 It can be seen that a through hole 1210 is provided on the first cover plate 1213, and the electrode terminal 1221 passes through the first cover plate 1213. A first insulating member 123 is provided between the first cover plate 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 plate 1213, and at the same time, the electrode terminal 1221 is insulated from the first cover plate 1213 to reduce the risk of short circuit. A through hole 1230 is provided on the first insulating member 123, and the electrode terminal 1221 is sequentially passed through the through hole 1230 and the through hole 1210. The through hole 1210 and the electrode terminal 1221 are connected. 1 is provided with a sealing member 124 for insulation and sealing, and 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 rivet block 1225 are provided on the side of the first cover plate 1213 away from the electrode assembly. The second insulating member 126 and the rivet block 1225 are also provided with openings. The electrode terminal 1221 passes through the openings of the second insulating member 126 and the rivet block 1225 in sequence, wherein the second insulating member 126 is used to insulate the electrode terminal 1221 from the first cover plate 1213, and the rivet block 1225 is used to fix the electrode terminal 1221 on the first cover plate 1213.

[0169] In some embodiments, reference Figure 4 The cover plate assembly 12 further includes a positioning member 125 , and the positioning member 125 includes at least two members to prevent the electrode terminal 1221 from deflecting and improve the force strength of the electrode terminal 1221 .

[0170] In some embodiments, reference Figure 5 The cover assembly includes a liquid injection hole 1211 for injecting electrolyte into the accommodating cavity of the shell 11.

[0171] refer to Figure 7-10 The cap plate assembly 12 includes a second cap plate 1214 and an electrode terminal 1221 .

[0172] In some embodiments, reference Figure 8 The disassembly diagram of the cover assembly 12, the cover assembly 12 includes a second cover 1214, an electrode terminal 1221, a first insulating member 123, a sealing member 124, a second insulating member 126, a rivet block 1225, a positioning member 125, and is assembled into Figure 7 The cover plate assembly 12 is shown.

[0173] In some embodiments, Figure 10 yes Figure 9 The cross-sectional diagram of the cover assembly along the BB' direction, combined with Figure 8 and Figure 10 It can be seen that a through hole 1210 is provided on the second cover plate 1214, and the electrode terminal 1221 passes through the second cover plate 1214. A first insulating member 123 is provided between the second cover plate 1214 and the electrode terminal 1221. This assembly method is used to isolate the electrical connection components in the housing 11 from the second cover plate 1214, and at the same time, the electrode terminal 1221 is insulated from the second cover plate 1214 to reduce the risk of short circuit. A through hole 1230 is provided on the first insulating member 123, and the electrode terminal 1221 is sequentially passed through the through hole 1230 and the through hole 1210. The through hole 1210 and the electrode terminal 1221 are connected. 1 is provided with a sealing member 124 for insulation and sealing, and 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 rivet 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 rivet block 1225 are also provided with openings. The electrode terminal 1221 passes through the openings of the second insulating member 126 and the rivet block 1225 in sequence, wherein the second insulating member 126 is used to insulate the electrode terminal 1221 from the second cover plate 1214, and the rivet block 1225 is used to fix the electrode terminal 1221 on the second cover plate 1214.

[0174] In some embodiments, reference Figure 8 The cover plate assembly 12 further includes a positioning member 125 , and the positioning member 125 includes at least two members to prevent the electrode terminal 1221 from deflecting and improve the force strength of the electrode terminal 1221 .

[0175] In this application, reference Figure 4 and Figure 8 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. In the direction perpendicular to the thickness direction of the cover plate, since the first limiting portion 1222 and the second limiting portion 1223 play a limiting role, their cross-sectional area is larger than that of the terminal body 1224, and the cross-sectional area of ​​the terminal body 1224 is often smaller.

[0176] As an example, the cover plate can be made of a material with a certain hardness and strength (such as aluminum alloy), which makes the cover plate have higher strength, reduces deformation of the cover plate when squeezed, and improves the safety performance of the battery cell. In some embodiments, a steel shell can be selected.

[0177] As an example, the cover plate and the housing 11 may be independent components.

[0178] As an example, the cover plate and the shell 11 can also be integrated. Specifically, at least one cover plate assembly 12 and the shell 11 can form a common connecting body before the electrode assembly and other components are placed in the shell. After the electrode assembly and other components are placed in the shell 11, the cover plate assembly 12 covers the opening of the shell along its length direction (or width direction).

[0179] In the present application, the first insulating member 123 and the second insulating member 126 can be independently made of plastic, rubber, etc.

[0180] As an example, refer to Figure 7 and Figure 8 The cover plate assembly 12 also includes a pressure relief mechanism 1212. The pressure relief mechanism 1212 and the second cover plate 1214 are two separate components that are separately molded and then assembled together. The pressure relief mechanism 1212 can be a component such as an explosion-proof disk, explosion-proof valve, or safety valve. The pressure relief mechanism 1212 can be attached to the cover plate by bonding, welding, or other methods. When the internal pressure of the battery cell reaches a threshold, the pressure relief mechanism 1212 opens at least a portion of the pressure relief holes, allowing the exhaust gas inside the battery cell to be discharged through the pressure relief holes to relieve the pressure inside the battery cell.

[0181] According to some embodiments of the present application, reference Figure 4 and Figure 8 The cross section of the terminal body 1224 along the direction perpendicular to the thickness of the cover plate is a rounded rectangular shape. Thus, when the cover plate area is small, the current capacity of the electrode terminal is improved.

[0182] According to some embodiments of the present application, the cap plate assembly 12 is disposed at both ends of the housing 11, and each cap plate assembly 12 includes at least two electrode terminals 1221. Specifically, the cap plate assembly 12 can be disposed at both ends of the length direction or the width direction of the housing 11, and each cap plate assembly 12 includes two electrode terminals 1221 with the same polarity or opposite polarity. This reduces the resistance of the battery cell and improves the current carrying capacity of the battery cell.

[0183] According to some embodiments of the present application, the cover plate assembly is arranged at both ends of the shell, each of the cover plate assemblies includes at least two electrode terminals, the polarities of the two electrode terminals are opposite, and the electrode terminals of the same polarity on the two cover plate assemblies are staggered along the length direction of the battery cell.

[0184] According to some embodiments of the present application, the electrode terminals of the same polarity are arranged diagonally along the length direction of the battery cell.

[0185] As a result, the temperature rise of the battery cells can be reduced during charging, thereby reducing the impedance of the battery cells.

[0186] As an example, refer to Figure 11 The cover plate assemblies 12 in the battery cell 1 are arranged at both ends of the shell 11 in the length direction, and each of the cover plate assemblies 12 includes two electrode terminals 1221 with opposite polarities.

[0187] refer to Figure 12-15 The cap plate assembly 12 includes a first cap plate 1213 and two electrode terminals 1221 with opposite polarities.

[0188] In some embodiments, reference Figure 13 The disassembly diagram of the cover assembly 12 includes a first cover 1213, two electrode terminals 1221, a first insulating member 123, two sealing members 124, two second insulating members 126, two rivet blocks 1225, four positioning members 125, and is assembled into Figure 12 The cover plate assembly 12 is shown.

[0189] In some embodiments, Figure 15 yes Figure 14 Schematic diagram of the cross section along CC' direction, combined with Figure 13 and Figure 15 It can be seen that two through holes 1210 are provided on the first cover plate 1213, and the two electrode terminals 1221 are respectively passed 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 to isolate the electrical connection components in the housing 11 from the first cover plate 1213, and at the same time, the electrode terminals 1221 are insulated 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 are respectively passed through the through holes 1230 and the through holes 1210 in sequence. The through holes 1210 and the two electrode terminals are connected. A sealing member 124 for insulation and sealing is provided between the electrodes 1221. The sealing member 124 is provided with an opening to allow the electrode terminal 1221 to pass through. Two second insulating members 126 and two rivet blocks 1225 are provided on the side of the first cover plate 1213 away from the electrode assembly. The second insulating members 126 and the rivet blocks 1225 are also provided with openings. The electrode terminals 1221 pass through the openings of the second insulating members 126 and the rivet blocks 1225 in sequence. The second insulating members 126 are used to insulate the electrode terminals 1221 from the first cover plate 1213. The two rivet blocks 1225 respectively fix the two electrode terminals 1221 to the first cover plate 1213. The first cover plate 1213 is provided with an injection hole 1211 for injecting electrolyte into the interior of the housing.

[0190] refer to Figure 16-19 The cap plate assembly 12 includes a second cap plate 1214 and two electrode terminals 1221 .

[0191] In some embodiments, reference Figure 17 The disassembly diagram of the cover assembly 12 includes a second cover 1214, two electrode terminals 1221, a first insulating member 123, two sealing members 124, two second insulating members 126, two rivet blocks 1225, four positioning members 125, and is assembled into Figure 16 The cover plate assembly 12 is shown.

[0192] In some embodiments, Figure 19 yes Figure 18 Schematic diagram of the cross section along the DD' direction, combined with Figure 17 and Figure 19 It can be seen that two through holes 1210 are provided on the second cover plate, and the two electrode terminals 1221 respectively penetrate the second cover plate 1214. A first insulating member 123 is provided between the second cover plate 1214 and the electrode terminal 1221. This assembly method is used to isolate the electrical connection components in the housing 11 and the second cover plate 1214, while making the electrode terminal 1221 and the second cover plate in an insulated state 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 are respectively penetrated through the corresponding through holes 1230 and the through holes 1210. The through holes 1210 are connected to the electrode ends. A sealing member 124 for insulation and sealing is provided between each of the sub-assemblies 1221. The sealing member 124 is provided with an opening to allow the electrode terminal 1221 to pass through. Two second insulating members 126 and two rivet blocks 1225 are provided on the side of the second cover plate 1214 away from the electrode assembly. The second insulating member 126 is also provided with an opening. The electrode terminals 1221 pass through the openings of the second insulating member 126 and the rivet blocks 1225 in sequence. The second insulating member 126 is used to insulate the electrode terminals 1221 from the second cover plate 1214, and the two rivet blocks 1225 are used to secure the two electrode terminals 1221 to the second cover plate 1214. A pressure relief mechanism 1212 is provided on the second cover plate 1214. When the pressure inside the housing exceeds a threshold, the pressure relief mechanism 1212 can release the pressure inside the housing.

[0193] refer to Figure 20The electrode assembly 10 includes four tabs. Two tabs extend from one end of the length of the electrode assembly 10: a first positive tab 231 and a first negative tab 321. Two tabs extend from the other end of the length of the electrode assembly 10: a second positive tab 232 and a second negative tab 322. The first positive tab 231 is electrically connected to the positive terminal on the first cover plate, the first negative tab 321 is electrically connected to the negative terminal on the first cover plate, the second positive tab 232 is electrically connected to the positive terminal on the second cover plate, and the second negative tab 322 is electrically connected to the negative terminal on the second cover plate. Thus, the electrode terminals of different polarities are arranged diagonally along the length of the battery cell, which can reduce the temperature rise of the battery cell during charging, thereby reducing the impedance of the battery cell.

[0194] refer to Figure 21 The electrode assembly 10 includes four tabs. Two tabs extend from one end of the electrode assembly 10 in the longitudinal direction: a first positive tab 231 and a first negative tab 321. Two tabs extend from the other end of the electrode assembly 10 in the longitudinal direction: a second positive tab 232 and a second negative tab 322. The first positive tab 231 is electrically connected to the positive terminal on the first cover plate, the first negative tab 321 is electrically connected to the negative terminal on the first cover plate, the second positive tab 232 is electrically connected to the positive terminal on the second cover plate, and the second negative tab 322 is electrically connected to the negative terminal on the second cover plate. In other words, the electrode terminals on each cover plate have different polarities, resulting in a total of four electrode terminals on each battery cell. This improves the current handling capacity of the battery cell while reducing problems such as unreasonable wiring and excessively long wiring harnesses caused by electrical connections between battery cells when multiple battery cells are assembled into a battery pack, making assembly easier.

[0195] According to some embodiments of the present application, reference Figure 22 The electrode assembly 10 further includes a negative electrode sheet 3. The positive electrode sheet 2 and the negative electrode sheet 3 are stacked, with a separator 4 disposed between the positive electrode sheet 2 and the negative electrode sheet 3. 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. This improves current transmission efficiency, reduces battery cell resistance, and enhances battery rate performance.

[0196] According to some embodiments of the present application, the positive electrode tab extends along the length direction of the positive electrode sheet or extends along the width direction thereof.

[0197] refer to Figure 23 , along the length direction of the positive electrode plate 2, only one tab extends out, refer to Figure 24 A positive electrode tab extends from each end along the length direction of the positive electrode sheet 2.

[0198] refer to Figure 25The positive electrode tab 23 extends along one end of the width direction of the positive electrode sheet 2. At this time, the size of the positive electrode tab 23 along the length direction of the positive electrode sheet 2 can occupy 70%-90% of the total length of the positive electrode sheet 2, thereby improving the current capacity of the battery cell.

[0199] In some embodiments, an L-shaped adapter plate may be welded to the positive electrode tab 23 to achieve electrical connection with the electrode terminals on the two cover plate assemblies arranged along the length direction of the battery cell.

[0200] refer to Figure 26 The positive electrode sheet 2 is provided with a first positive electrode tab 231 and a second positive electrode tab 232 on both sides along the width direction thereof.

[0201] According to some embodiments of the present application, the negative electrode tab may extend from the negative electrode sheet along its length or width, thereby improving current transmission efficiency, reducing the resistance of the battery cell, and improving the rate performance of the battery.

[0202] refer to Figure 27 , the negative electrode tab 32 extends along the length direction of the negative electrode plate 3; Figure 28 The negative electrode tabs extend along the length direction of the negative electrode sheet 3 to form a first negative electrode tab 321 and a second negative electrode tab 322 .

[0203] refer to Figure 29 The negative electrode tab 32 extends along the width direction of the negative electrode plate 3. At this time, the size of the negative electrode tab 23 along the length direction of the negative electrode plate 3 can occupy 70%-90% of the total length of the negative electrode plate 3, thereby improving the current capacity of the battery cell.

[0204] refer to Figure 30 A first negative electrode tab 321 and a second negative electrode tab 322 are respectively provided on both sides of the negative electrode sheet along its width direction.

[0205] In some embodiments, an L-shaped adapter plate may 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.

[0206] In some embodiments, the battery cell of the present application is a laminated battery, in which the positive electrode sheets and the negative electrode sheets are stacked, each layer of the positive electrode sheets is provided with a positive electrode tab, and each layer of the negative electrode sheets is provided with a negative electrode tab.

[0207] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0208] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0209] 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, at least one side of the negative electrode current collector is provided with a negative electrode film layer, and the compaction density of the negative electrode film layer corresponding to the battery cell at 100% SOC can be 1.15 g / cm 3 -1.36g / cm 3 , for example, can be 1.15 g / cm 3 , 1.2g / cm 3 , 1.25g / cm 3 , 1.3g / cm 3 , 1.36g / cm 3 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 -1.36g / cm 3 This increases the energy density of the battery cell.

[0210] The present application provides a method for testing the compaction density of the negative electrode film layer: charge to 3.8V at a constant current of 1 / 3C, charge to 0.05C at a constant voltage of 3.8V, disassemble the battery cell to obtain the negative electrode sheet, for example, take a single-sided coated negative electrode sheet (if it is a double-sided coated sheet, the negative electrode film layer on one side can be wiped off first), punch it into small discs 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 sheet, 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.

[0211] According to some embodiments of the present application, the single-side coating weight of the negative electrode film layer can be 90 mg / 1540.25 mm 2 -170mg / 1540.25mm 2 , for example, it can be 90mg / 1540.25mm 2 、110mg / 1540.25mm 2 、130mg / 1540.25mm 2 、150mg / 1540.25mm 2 、170mg / 1540.25mm 2 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 -150mg / 1540.25mm 2 This increases the energy density of the battery cell.

[0212] This application provides a method for measuring the coating weight of the negative electrode film layer: A battery cell is disassembled to remove the negative electrode sheet. For example, a single-sided coated negative electrode sheet (for double-sided coated sheets, the negative electrode film layer on one side can be wiped off first) is punched into small discs with an area of ​​S2. These discs are weighed and recorded as M3. The negative electrode film layer of the weighed negative electrode sheet is then wiped off, and the weight of the negative electrode current collector is weighed and recorded as M2. The single-sided coating weight of the negative electrode film layer = (M3 - M2) / S2.

[0213] According to some embodiments of the present application, the negative electrode film layer includes a negative electrode active material, and the charge capacity of the negative electrode active material at a 0.1C rate is 350mAh / g-480mAh / g, for example, 350mAh / g, 370mAh / g, 390mAh / g, 410mAh / g, 430mAh / g, 450mAh / g, 480mAh / g, etc., or can be within a range consisting of any of the above values. Thus, the energy density of the battery cell is improved.

[0214] According to some embodiments of the present application, reference Figure 31 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 arranged on at least one side of the negative electrode current collector 30, and the second negative electrode film layer 312 is arranged on the side of the first negative electrode film layer 311 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 size of the first graphite particles is larger than the volume average particle size of the second graphite particles. During fast charging, the overpotential of the second negative electrode film layer 312 is generally higher. By reducing the volume average particle size of the second graphite particles, the solid-phase transmission path of lithium ions can be shortened, the diffusion rate of lithium ions can be increased, and the fast charging performance can be improved. At the same time, the problem of lithium plating on the negative electrode surface can be improved.

[0215] According to some embodiments of the present application, the first graphite particles include natural graphite, thereby increasing the compaction density of the negative electrode sheet.

[0216] According to some embodiments of the present application, the volume average particle size Dv50 of the first graphite particles can be 7µm-18.5µm, for example, 7µm, 11µm, 13µm, 15µm, 17µm, 18.5µm, etc., or can be a range consisting of any of the above values.

[0217] According to some embodiments of the present application, the volume average particle size Dv50 of the second graphite particles may be 7µm to 14.3µm, for example, 7µm, 9µm, 11µm, 13µm, 14.3µm, or any range thereof. Thus, the smaller volume average particle size of the second graphite particles can shorten the solid-phase transport path of lithium ions and improve the fast-charging performance of the battery cell.

[0218] According to some embodiments of the present application, the first negative electrode film layer and the second negative electrode film layer each independently comprise a silicon-based material. Based on the total mass of the negative electrode film layer, the mass percentage of silicon can be 0.3%-10%, for example, 0.3%, 1%, 3%, 5%, 7%, 9%, 10%, or any range thereof. This increases the capacity of the negative electrode active material and the energy density of the battery cell.

[0219] In the present application, the content of silicon element can be tested by inductively coupled plasma optical emission spectroscopy (ICP-OES).

[0220] According to some embodiments of the present application, the thickness of the negative electrode current collector is 4µm-8.5µm, for example, 4µm, 5µm, 6µm, 7µm, 8µm, 8.5µm, etc., or any range thereof. Thus, while reducing the space occupied by the internal space of the housing 11, the flow capacity of the negative electrode current collector is improved.

[0221] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0222] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, 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 drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0223] According to some embodiments of the present application, the battery cell is configured to charge from 10% SOC to 80% SOC in a time range of 5 min to 10.5 min, for example, 5 min, 7 min, 9 min, 10.5 min, etc., or in a range of any of the above values. Thus, the fast charging performance of the battery cell is improved. According to some specific embodiments of the present application, the battery cell is configured to charge from 10% SOC to 80% SOC in a time range of 7 min to 10 min.

[0224] In some embodiments, the battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0225] 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.

[0226] A second aspect of the present application provides a battery device, comprising the battery cell provided in the first aspect of the present application, wherein the battery device is at least one of a battery module, a battery pack, and an energy storage device.

[0227] A third aspect of the present application provides an electrical device, comprising the battery cell provided in the first aspect of the present application or the battery device provided in the second aspect of the present application, wherein the battery cell or the battery device is used to provide electrical energy.

[0228] 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 and satellites, energy storage systems, etc., but are not limited thereto.

[0229] As the electrical equipment, a battery device can be selected according to its usage requirements.

[0230] Figure 32 This is an example of an electric device. This electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the electric device, a battery pack or battery module can be used.

[0231] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be lightweight and thin, and may use a battery cell as a power source.

[0232] In order 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 with reference to the embodiments and 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 is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0233] Example 1

[0234] 1. Positive electrode

[0235] The positive electrode sheet includes a positive electrode current collector aluminum foil with a positive electrode film layer on both surfaces. At 100% SOC, the compaction density is 2.6g / cm 3 The coating weight of the single-sided positive electrode film is 280mg / 1540.25mm 2 Based on the total mass of the single-sided positive electrode film layer, the positive electrode film layer includes 94% by mass of lithium iron phosphate material, 2% of the first lithium supplement additive lithium ferrite, 1% of the second lithium supplement additive lithium titanate, 1% of the conductive agent carbon black, and 2% of the binder polyvinylidene fluoride (PVDF). The average particle size of the primary particles of the lithium iron phosphate material is 230 nm, the volume average particle size Dv50 of the secondary particles is 1.3 μm, and the volume particle size Dv10 is 0.45 μm. The surface of the lithium iron phosphate has a carbon coating layer. Based on the total mass of the lithium iron phosphate, the mass of the carbon coating layer accounts for 1.18%.

[0236] 2. Negative electrode

[0237] The negative electrode sheet includes a negative electrode current collector copper foil, and there are negative electrode films on both surfaces of the copper foil. The negative electrode films include a first negative electrode film layer and a second negative electrode film layer. The mass ratio of graphite active material and conductive agent carbon black, binder styrene butadiene rubber, and thickener sodium carboxymethyl cellulose in the first negative electrode film layer is 96.5:0.5:2:1. The mass ratio of graphite active material and conductive agent carbon black, binder styrene butadiene rubber, and thickener sodium carboxymethyl cellulose in the second negative electrode film layer is 97.5:0.5:1:1. At 100% SOC, the compaction density of the negative electrode film layer is 1.6 g / cm 3 The single-sided coating weight of the negative electrode film is 130mg / 1540.25cm 2 .

[0238] 3. Electrolyte

[0239] The electrolyte includes a linear carboxylate, a cyclic carbonate solvent, an electrolyte salt, and an additive. The linear carboxylate is II-1, the cyclic carbonate solvent is ethylene carbonate (EC), the electrolyte salt is lithium hexafluorophosphate, and the additive is vinylene carbonate (VC). Based on the total mass of the electrolyte, II-1 accounts for 5% by weight, EC accounts for 72% by weight, lithium hexafluorophosphate accounts for 15% by weight, and VC accounts for 8% by weight. The electrolyte has a conductivity of 9.5 mS / cm, a viscosity of 3.2 mPa·s, and a density of 1.22 g / mL.

[0240] 4. Isolation film

[0241] Polyethylene film, thickness 7μm.

[0242] 5. Battery cells

[0243] The battery cell includes a shell, a cover assembly, an electrode assembly and an electrolyte. The cover assembly is located at both ends of the shell in the length direction. The structure of a cover assembly is shown in the figure below. Figure 2 , another cover assembly structure reference Figure 6 That is, one cover assembly includes a positive terminal, and the other cover assembly includes a negative terminal. The electrode assembly and the electrolyte are arranged in the accommodating cavity formed by the shell and the cover assembly. The electrode assembly is a laminated electrode assembly, which is made by stacking the above-mentioned positive electrode sheet, isolation membrane, and negative electrode sheet. Along the length direction of the electrode assembly, a positive electrode tab extends from one end and a negative electrode tab extends from the other end. The positive electrode tab is electrically connected to the positive terminal, and the negative electrode tab is electrically connected to the negative terminal.

[0244] Performance Testing

[0245] 1.DCR

[0246] The battery cell is charged to 3.8V at 25°C with a constant current of 0.33C, charged to 0.05C at a constant voltage, and left for 30 minutes. It is discharged to 2.0V at a constant current of 0.33C, at which time the discharge capacity is A0, in Ah. It is left for 30 minutes, charged to 3.8V at a constant current of 0.33C, charged to 0.05C at a constant voltage, and discharged to 0.5A0 at a constant current of 0.33C. The cell SOC is adjusted and left for 120 minutes. The voltage of the last 1s is recorded as V0, in V. The current size of 4A0 (in A) is discharged at a constant current for 30 seconds. The discharge end voltage is V1, in V. After 30 seconds, DCR = (V0-V1) / 4A0×1000, in mΩ.

[0247] 2. High temperature cycle life

[0248] At an ambient temperature of 45°C, the battery cell is charged to 3.8V with step charge, charged to 0.05C with constant voltage, left for 30 minutes, discharged to 2.5V with 0.5C constant current, and left for 30 minutes. This is one charge and discharge cycle. Repeat the above charge and discharge cycles until the capacity of the battery cell is 80% of the initial capacity. The number of charge and discharge cycles is the high-temperature cycle life of the battery cell.

[0249] Step charge charging steps are:

[0250] Charge from 0% SOC to 10% SOC at 1C constant current;

[0251] Charge from 10% SOC to 30% SOC at 7.0C constant current;

[0252] Charge from 30% SOC to 35% SOC at 6.2C constant current;

[0253] Charge from 35% SOC to 40% SOC at 5.7C constant current;

[0254] Charge from 40% SOC to 45% SOC at 5.2C constant current;

[0255] Charge from 45% SOC to 50% SOC at 4.8C constant current;

[0256] Charge from 50% SOC to 55% SOC at 4.6C constant current;

[0257] Charge from 55% SOC to 60% SOC at 4.4C constant current;

[0258] Charge from 60% SOC to 65% SOC at 4.2C constant current;

[0259] Charge from 65% SOC to 70% SOC at 3.9C constant current;

[0260] Charge from 70% SOC to 75% SOC at 3.5C constant current;

[0261] Charge from 75% SOC to 80% SOC at 3.0C constant current;

[0262] Charge from 80% SOC to 100% SOC at a constant current of 0.33C.

[0263] 3. Charging time

[0264] Calculate the time it takes to charge a battery cell from 10% SOC to 80% SOC. The specific charging process is as follows:

[0265] Charge from 0% SOC to 10% SOC at 1C constant current; charge from 10% SOC to 30% SOC at 7.0C constant current; charge from 30% SOC to 35% SOC at 6.2C constant current; charge from 35% SOC to 40% SOC at 5.7C constant current; charge from 40% SOC to 45% SOC at 5.2C constant current; charge from 45% SOC to 50% SOC at 4.8C constant current; charge from 50% SOC to 50% SOC at 4.6C constant current. Charge from 55% SOC to 55% SOC at a constant current of 4.4C; charge from 55% SOC to 60% SOC at a constant current of 4.2C; charge from 60% SOC to 65% SOC at a constant current of 3.9C; charge from 65% SOC to 70% SOC at a constant current of 3.5C; charge from 70% SOC to 75% SOC at a constant current of 3.0C; and charge from 75% SOC to 80% SOC. The total time of each charging period is the charging time.

[0266] Example 2

[0267] The preparation method of the battery cell is the same as that of Example 1, except that the mass proportion of II-1 is 10% and the mass proportion of EC is 67%.

[0268] Example 3

[0269] The preparation method of the battery cell is the same as that of Example 1, except that the mass proportion of II-1 is 30% and the mass proportion of EC is 47%.

[0270] Example 4

[0271] The preparation method of the battery cell is the same as that of Example 1, except that the mass proportion of II-1 is 60% and the mass proportion of EC is 17%.

[0272] Comparative Example 1

[0273] The preparation method of the battery cell is the same as that of Example 1, except that the mass proportion of II-1 is 3% and the mass proportion of EC is 74%.

[0274] Comparative Example 2

[0275] The preparation method of the battery cell is the same as that of Example 1, except that the mass proportion of II-1 is 65% and the mass proportion of EC is 12%.

[0276] Comparative Example 3

[0277] The preparation method of the battery cell is the same as that of Example 1, except that, based on the total mass of the single-sided positive electrode film layer, the positive electrode film layer includes 97% by mass of lithium iron phosphate material, 1% of conductive agent carbon black, and 2% of binder PVDF.

[0278] The specific differences and test results of the battery cells in Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Table 1.

[0279]

[0280] As can be seen from the comparison between Examples 1 to 4 and Comparative Examples 1 to 3, the present application can improve the ionic conductivity of the electrolyte, reduce the DCR of the battery cell, and improve the fast charging performance of the battery cell by adding chain carboxylic acid esters to the electrolyte. As the content of chain carboxylic acid esters increases, the reaction rate at the phase interface increases accordingly, the stability of the SEI film decreases, and the high-temperature cycle life of the battery cell gradually decreases. As can be seen from Example 2 and Comparative Example 3, by adding lithium ferrite and lithium titanate to the positive electrode sheet, a battery cell with a lower DCR and a higher high-temperature cycle life can be obtained. This shows that by adding Fe-containing oxides or Ni-containing oxides to the positive electrode film layer, the stability of the SEI film can be improved, the continuity of charge transfer can be improved, and the increase in impedance caused by the instability of the SEI film can be reduced, thereby improving the fast charging performance of the battery cell while improving the high-temperature cycle life of the battery cell.

[0281] Example 5

[0282] The preparation method of the battery cell is the same as that of Example 2, except that the mass proportion of lithium ferrite is 0.1%, the positive electrode film layer does not contain lithium titanate, and the mass proportion of lithium iron phosphate material is 96.9%.

[0283] Example 6

[0284] The preparation method of the battery cell is the same as that of Example 2, except that the mass proportion of lithium ferrite is 2%, the positive electrode film layer does not contain lithium titanate, and the mass proportion of lithium iron phosphate material is 95%.

[0285] Example 7

[0286] The preparation method of the battery cell is the same as that of Example 2, except that the mass proportion of lithium ferrite is 5%, the positive electrode film layer does not contain lithium titanate, and the mass proportion of lithium iron phosphate material is 92%.

[0287] Example 8

[0288] The preparation method of the battery cell is the same as that of Example 2, except that the mass proportion of lithium ferrite is 5.5%, the positive electrode film layer does not contain lithium titanate, and the mass proportion of lithium iron phosphate material is 91.5%.

[0289] Example 9

[0290] The preparation method of the battery cell is the same as that of Example 2, except that the mass proportion of lithium ferrite is 0.05%, the mass proportion of lithium titanate is 0.05%, and the mass proportion of lithium iron phosphate material is 96.9%.

[0291] Example 10

[0292] The preparation method of the battery cell is the same as that of Example 2, except that the mass proportion of lithium ferrite is 1%, the mass proportion of lithium titanate is 1%, and the mass proportion of lithium iron phosphate material is 93%.

[0293] Example 11

[0294] The preparation method of the battery cell is the same as that of Example 2, except that the mass proportion of lithium ferrite is 3.5%, the mass proportion of lithium titanate is 1.5%, and the mass proportion of lithium iron phosphate material is 92%.

[0295] Example 12

[0296] The preparation method of the battery cell is the same as that of Example 2, except that the mass proportion of lithium ferrite is 3.5%, the mass proportion of lithium titanate is 2%, and the mass proportion of lithium iron phosphate material is 91.5%.

[0297] The specific differences and test results of the battery cells in Comparative Example 3 and Examples 5 to 12 are shown in Table 2.

[0298] Table 2

[0299]

[0300] It can be seen from the comparison between Examples 5 to 12 and Comparative Example 3 that the cycle life of the battery cell can be improved by adding a lithium supplement additive to the positive electrode film layer.

[0301] As can be seen from Examples 5-12, when the positive electrode film layer contains both the first and second lithium-supplementing additives, the DCR of the battery cell can be further reduced, and the high-temperature cycle life of the battery cell can be improved, compared to adding only the first lithium-supplementing additive. In other words, while the first lithium-supplementing additive improves SEI film stability and replenishes lithium, the second lithium-supplementing additive can further enhance the lithium-supplementing effect, thereby extending the high-temperature cycle life of the battery cell.

[0302] Example 13

[0303] The preparation method of the battery cell is the same as that of Example 2, except that the coating weight of the single-sided positive electrode film layer is 200 mg / 1540.25 mm 2 .

[0304] Example 14

[0305] The preparation method of the battery cell is the same as that of Example 2, except that the coating weight of the single-sided positive electrode film layer is 240 mg / 1540.25 mm 2 .

[0306] Example 15

[0307] The preparation method of the battery cell is the same as that of Example 2, except that the coating weight of the single-sided positive electrode film layer is 300 mg / 1540.25 mm 2 .

[0308] Example 16

[0309] The preparation method of the battery cell is the same as that of Example 2, except that the coating weight of the single-sided positive electrode film layer is 340 mg / 1540.25 mm 2 .

[0310] Example 17

[0311] The preparation method of the battery cell is the same as that of Example 2, except that, at 100% SOC, the compaction density of the positive electrode film layer is 2.5 g / cm 3 .

[0312] Example 18

[0313] The preparation method of the battery cell is the same as that of Example 2, except that, at 100% SOC, the compaction density of the positive electrode film layer is 2.8 g / cm 3 .

[0314] The detailed differences between the battery cells in Examples 13 to 18 and the test results are shown in Table 3.

[0315] Table 3

[0316]

[0317] It can be seen from Examples 13 to 18 that by adjusting the coating weight and compaction density of the positive electrode film layer, the resistance and cycle life of the battery cell can be adjusted to obtain a battery cell with excellent fast charging performance and cycle performance.

[0318] Example 19

[0319] The preparation method of the battery monomer is the same as that of Example 2, except that the chain carboxylate is II-2.

[0320] Example 20

[0321] The preparation method of the battery monomer is the same as that of Example 2, except that the chain carboxylate is II-3.

[0322] Example 21

[0323] The preparation method of the battery monomer is the same as that of Example 2, except that the chain carboxylate is II-5.

[0324] Example 22

[0325] The preparation method of the battery monomer is the same as that of Example 2, except that the chain carboxylate is II-7.

[0326] Example 23

[0327] The preparation method of the battery monomer is the same as that of Example 2, except that the chain carboxylate is II-8.

[0328] The detailed differences between the battery cells in Examples 19 to 23 and the test results are shown in Table 4.

[0329] Table 4

[0330]

[0331] It can be seen from Examples 19 to 23 that by selecting different types of chain carboxylates, an electrolyte with higher conductivity can be obtained, thereby reducing the resistance of the battery cell and improving the fast charging performance of the battery cell.

[0332] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, wherein: include: A positive electrode plate, the positive electrode plate comprising 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 comprising a lithium-containing phosphate and a lithium supplement additive, the lithium supplement additive comprising at least one of an Fe oxide or a Ni oxide; A negative electrode plate, the negative electrode plate comprising a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector, the negative electrode film layer comprising graphite; The electrolyte comprises a chain carboxylate, and the conductivity of the electrolyte at room temperature is 10 mS / cm-18 mS / cm, Based on the total mass of the electrolyte, the mass proportion of the chain carboxylic acid ester is 5%-60%.

2. The battery cell according to claim 1, wherein: The Fe oxide or the Ni oxide includes lithium and serves as a first lithium supplement additive to supplement lithium ions in the battery cell.

3. The battery cell according to claim 2, wherein: The first lithium supplement additive includes at least one of lithium nickelate and lithium ferrite.

4. The battery cell according to claim 2, wherein: The first lithium supplement additive includes Li e M1 f O g , wherein 1≤e≤6, 1≤f≤6, 2≤g≤12, and M1 includes one or more of Ni, Co, Mn, and Fe.

5. The battery cell according to claim 2, wherein: The first lithium supplement additive includes Li2NiO2 and / or Li5FeO4.

6. The battery cell according to claim 2, wherein: The first lithium supplement additive includes Li n NiO m and / or Li p FeO q , where 0≤n≤2, 0<m≤2, 0<p≤5, 0<q≤4.

7. The battery cell according to claim 2, wherein: The first lithium supplement additive includes NiO m and / or Li p FeO q , where 0<m≤2, 0<p≤1, 0<q≤2.

8. The battery cell according to claim 2, wherein: At least a portion of the surface of the first lithium supplementing additive is provided with a coating layer, and the coating layer includes one or more of the following elements: C, Al, Zr, P, and S.

9. The battery cell according to claim 8, wherein: The coating layer includes one or more of carbon materials, aluminum oxide, zirconium oxide, lithium phosphide, and lithium sulfide.

10. The battery cell according to claim 2, wherein: The first lithium supplement additive further includes a doping element, and the doping element includes one or more of Al, Zr, and B.

11. The battery cell according to claim 10, wherein: Based on the total mass of the first lithium supplementing additive, the contents of Al, Zr and B in the first lithium supplementing additive are independently 50 ppm to 1000 ppm.

12. The battery cell according to claim 2, wherein: The lithium supplement additive also includes a second lithium supplement additive, which includes one or more of lithium nickel cobalt manganese oxide, lithium phosphate, dilithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium metamanganate, lithium tartrate, and trilithium citrate.

13. The battery cell according to claim 12, wherein: Based on the total mass of the positive electrode film layer, the total mass of the first lithium supplement additive and the second lithium supplement additive accounts for 0.1%-5%.

14. The battery cell according to claim 1, wherein The lithium-containing phosphate includes a compound shown in Formula I: Wherein, 0.5≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤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, M2 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.

15. The battery cell according to claim 1, wherein The lithium-containing phosphate includes lithium iron phosphate material.

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

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

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

19. The battery cell according to claim 1, wherein: Based on the total mass of the electrolyte, the mass proportion of the chain carboxylic acid ester is 8%-30%.

20. The battery cell according to claim 1, wherein The viscosity of the electrolyte at room temperature is 1.5 mPa·s-5.5 mPa·s.

21. The battery cell according to claim 1, wherein The density of the electrolyte at room temperature is 1.05 g / mL-1.35 g / mL.

22. The battery cell according to claim 21, wherein The chain carboxylic acid ester includes a compound shown in Formula II: Formula II, 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.

23. The battery cell according to claim 22, wherein: R1 includes one or more of the hydrogen atom, C1-C3 alkyl group, C1-C3 haloalkyl group; and / or R2 includes one or more of C1-C3 alkyl and C1-C3 haloalkyl.

24. The battery cell according to claim 22 or 23, wherein: The chain carboxylic acid ester includes Formula II-1, Formula II-2, Formula II-3, Formula II-4, Formula II-5, Formula II-6, Formula II-7, One or more of formula II-8.

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

26. The battery cell according to claim 25, wherein: The single-sided coating weight of the positive electrode film layer is 240 mg / 1540.25 mm 2 -300mg / 1540.25mm 2 .

27. The battery cell according to claim 1, wherein The lithium-containing phosphate has a charge capacity of 150 mAh / g to 170 mAh / g at a 0.1 C rate.

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

29. The battery cell according to claim 1, wherein The positive electrode sheets and the negative electrode sheets are stacked, each layer of the positive electrode sheets is provided with a positive electrode tab, and each layer of the negative electrode sheets is provided with a negative electrode tab.

30. The battery cell according to claim 1, wherein The battery cell further comprises: a housing and a cover assembly, wherein the housing and the cover assembly define a receiving cavity; The cover plate assembly is arranged at at least one end of the shell, and the cover plate assembly includes a cover plate and an electrode terminal. A through hole is provided on the cover plate, and 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.

31. The battery cell according to claim 30, wherein: 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.

32. The battery cell according to claim 30, 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 polarities of the two electrode terminals are opposite, and the electrode terminals of the same polarity on the two cover plate assemblies are staggered along the length direction of the battery cell.

33. The battery cell according to claim 32, wherein: The electrode terminals of the same polarity are arranged diagonally along the length direction of the battery cell.

34. The battery cell according to claim 29, wherein The positive electrode tab extends along the length direction of the positive electrode sheet or extends along the width direction thereof; and / or The negative electrode tab extends along the length direction of the negative electrode plate or extends along the width direction of the negative electrode plate.

35. The battery cell according to claim 30, wherein Along a direction perpendicular to the thickness direction of the cover plate, the cross section of the terminal body is a rounded rectangle.

36. The battery cell according to claim 1, wherein The battery cells are configured to be charged from 10% SOC to 80% SOC in a time range of 5 min to 10.5 min.

37. The battery cell according to claim 36, wherein: The battery cells are configured to be charged from 10% SOC to 80% SOC in a time of 7 minutes to 10 minutes.

38. A battery device, wherein: The battery device comprises the battery cell according to any one of claims 1 to 37, wherein the battery device is at least one of a battery module and a battery pack.

39. An electrical device, wherein: The battery cell according to any one of claims 1 to 37 or the battery device according to claim 38 is used to provide electrical energy.

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