Battery monomer, battery device and electric equipment

Abstract

The invention provides a battery monomer, a battery device and electric equipment, the battery monomer comprises a positive pole piece, the positive pole piece comprises a positive pole film layer, the positive pole film layer comprises lithium-containing phosphate and a lithium supplement additive, and the lithium supplement additive comprises at least one of an oxide of Fe or an oxide of Ni; a negative pole piece; the electrolyte comprises chain carboxylic ester, and the conductivity of the electrolyte at the normal temperature ranges from 10 mS / cm to 18 mS / cm. Therefore, by improving the conductivity of the electrolyte and improving the fast charging performance of the battery monomer, and meanwhile, at least one of the Fe oxide or the Ni oxide is added into the positive electrode film layer, the stability of a negative electrode electrolyte interface film (SEI film) is improved, the gas production of the battery monomer is reduced, the fast charging performance of the battery monomer is improved, and the service life of the battery monomer is prolonged. And the high-temperature cycle life of the battery monomer is prolonged.

Description

[0001] This application claims the priority of PCT International Application PCT / CN2025 / 071092, entitled "Battery Cell, Battery Device and Electrical Equipment", filed on January 7, 2025, the entire content of which is incorporated herein by reference. Technical Field

[0002] This application relates to the field of batteries, and specifically, to battery cells, battery devices and electrical equipment. Background Art

[0003] Batteries are not only applied to energy storage power systems such as hydroelectric, thermal, wind and solar power stations, but also widely used in electric transportation such as electric bicycles, electric motorcycles, electric vehicles, as well as in multiple fields such as military equipment and aerospace. When charging the battery at a high rate, the battery generates heat severely, which will affect the long-term performance of the battery. Summary of the Invention

[0004] In a first aspect of the present application, there is provided a battery cell, the battery cell includes a positive electrode plate, the positive electrode plate includes a positive electrode current collector and a positive electrode film layer provided on at least one side of the positive electrode current collector, the positive electrode film layer includes a lithium-containing phosphate and a lithium supplement additive, the lithium supplement additive includes at least one of an oxide of Fe or an oxide of Ni; a negative electrode plate, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector, the negative electrode film layer includes graphite; an electrolyte, the electrolyte includes a chain carboxylic ester, and the conductivity of the electrolyte at room temperature is 10 mS / cm - 18 mS / cm. 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 oxide of Fe or an oxide of Ni to the positive electrode film layer, the stability of the solid electrolyte interface (SEI) film on the negative electrode is improved, and the gas generation of the battery cell is reduced. While improving the fast charging performance of the battery cell, the high-temperature cycle life of the battery cell is improved.

[0005] According to some embodiments of the present application, the oxide of Fe or the oxide of Ni includes lithium and serves as a first lithium supplement additive to supplement lithium ions in the battery cell. Thus, while supplementing lithium, the first lithium supplement additive can also release oxygen elements to participate in the formation of the SEI film, improve the negative electrode interface impedance, and improve 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. Thus, the cycle life of the battery cell is improved.

[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 element, Co element, Mn element, and Fe element. Thus, additional lithium is provided during the first charging process, and at the same time, it participates in the formation of the SEI film, 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 Li 2 NiO 2 and / or Li 5 FeO 4 . Thus, the lithium supplement effect is improved, the stability of the negative electrode SEI film is improved, and the high-temperature cycle life of the battery cell is improved.

[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, 0 < q ≤ 4. That is, after the first lithium supplement additive decomposes, it will transform into a partially delithiated state, and the released lithium ions can be used for lithium supplementation, and the released oxygen-containing substances 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, 0 < q ≤ 2. That is, after the first lithium supplement additive decomposes, it will transform into a fully delithiated state, and the released lithium ions can be used for lithium supplementation, and the released oxygen-containing substances 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 part of the surface of the first lithium supplement additive is provided with a coating layer, and the coating layer includes one or more of C element, Al element, Zr element, P element, and S element. Thus, the air stability of the first lithium supplement additive is improved, and at the same time, the ion-conducting performance of the first lithium supplement additive is improved.

[0012] According to some embodiments of the present application, the coating layer includes one or more of carbon materials, oxides of aluminum, oxides of zirconium, phosphides of lithium, sulfides of lithium. Thus, the air stability of the first lithium supplement additive is improved, and at the same time, the ion-conducting performance of the first lithium supplement additive is improved.

[0013] 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 element, Zr element, and B element. Thereby, the decomposition voltage of the first lithium supplement additive is reduced, and the lithium supplement effect is improved.

[0014] According to some embodiments of the present application, based on the total mass of the first lithium supplement additive, the contents of Al element, Zr element, and B element in the first lithium supplement additive are each independently 50 ppm - 1000 ppm. Thereby, 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, the lithium supplement additive further 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 manganate, lithium tartrate, and lithium citrate. Thereby, the cycle life of the battery cell is improved.

[0016] According to some embodiments of the present application, based on the total mass of the positive electrode film layer, the total mass ratio of the first lithium supplement additive and the second lithium supplement additive is 0.1% - 5%. Thereby, the lithium supplement effect is improved.

[0017] According to some embodiments of the present application, the lithium-containing phosphate includes the compound shown in Formula I:

[0018] where 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. Thereby, the safety performance and cycle life of the battery cell are improved.

[0019] According to some embodiments of the present application, the lithium-containing phosphate includes a lithium iron phosphate material. Thereby, the safety performance and cycle life of the battery cell are improved.

[0020] According to some embodiments of the present application, the lithium-containing phosphate is granular, and the volume average particle size Dv50 of the lithium-containing phosphate is 1 µm - 2 µm. Thereby, the migration path of lithium ions in the solid phase is shortened, the polarization of the battery cell is reduced, and the heat generation of the battery cell is reduced.

[0021] According to some embodiments of the present application, the volume particle size Dv10 of the lithium-containing phosphate is 0.4 µm - 0.7 µm. Thereby, the migration path of lithium ions in the solid phase is shortened, the polarization of the battery cell is reduced, and the heat generation of the battery cell is reduced.

[0022] According to some embodiments of the present application, the lithium-containing phosphate includes secondary particles, and the average particle size of the primary particles in the secondary particles is 200 nm - 500 nm. Thereby, the migration path of lithium ions in the solid phase is shortened, the polarization of the battery cell is reduced, and the heat generation of the battery cell is reduced.

[0023] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass ratio of the chain carboxylic ester is 5% - 60%, and may be optionally 8% - 30%. Thereby, the viscosity of the electrolyte is reduced, the internal resistance of the battery cell is reduced, and the fast charging performance of the battery cell is improved.

[0024] 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.

[0025] 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.

[0026] Thereby, 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.

[0027] According to some embodiments of the present application, the chain carboxylic ester includes the compound shown in Formula II: Formula II, wherein, R 1 includes a hydrogen atom, C 1 -C 5 alkyl, C 1 -C 5 haloalkyl, or one or more of them, and R 2 includes C 1 -C 5 alkyl, C 1 -C 5 haloalkyl, or one or more of them. Thereby, the chain carboxylic esters of the above types have a relatively small molecular weight, which can increase the conductivity of the electrolyte and improve the fast charging performance of the battery cell.

[0028] According to some embodiments of the present application, R 1 includes one or more of the hydrogen atom, C 1 -C 3 alkyl, C 1 -C 3 haloalkyl; and / or R 2 includes one or more of C 1 -C 3 alkyl, C 1 -C 3 haloalkyl. Thus, the chain carboxylic esters of the above types have a relatively small molecular weight, which can improve the conductivity of the electrolyte and the fast charging performance of the battery cell.

[0029] According to some embodiments of the present application, wherein the chain carboxylic 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.

[0030] Thus, the chain carboxylic esters of the above types have a relatively small molecular weight, which can improve the conductivity of the electrolyte and the fast charging performance of the battery cell.

[0031] According to some embodiments of the present application, the single-sided coating weight of the positive electrode film layer is 200 mg / 1540.25 mm 2 -340 mg / 1540.25 mm 2 , and may be optionally 240 mg / 1540.25 mm 2 -300 mg / 1540.25 mm 2 . Thus, the energy density of the battery cell is improved.

[0032] According to some embodiments of the present application, the charging specific capacity of the lithium-containing phosphate at a 0.1C rate is 150 mAh / g - 170 mAh / g. Thus, the energy density of the battery cell is improved.

[0033] According to some embodiments of the present application, the compaction density of the positive electrode film layer corresponding to the battery cell at 100% SOC is 2.5 g / cm 3 -2.8 g / cm 3 . Thus, the energy density of the battery cell is improved.

[0034] According to some embodiments of the present application, the electrode assembly further comprises a negative electrode sheet, the positive electrode sheet and the negative electrode sheet are stacked, each layer of the positive electrode sheet is provided with a positive electrode tab, and each layer of the negative electrode sheet is provided with a negative electrode tab. Thus, the current transmission efficiency is improved, the resistance of the battery cell is reduced, and the rate performance of the battery is improved.

[0035] According to some embodiments of the present application, the battery cell further includes: a shell and a cover plate assembly, the shell and the cover plate assembly define a receiving cavity; the cover plate assembly is arranged at at least one end of the shell, 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 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 receiving cavity, and the second limiting portion is located on the side of the cover plate away from the receiving cavity. Thus, the structural stability of the electrode terminal is improved, the risk of the electrode terminal falling off from the through hole is reduced, and the cycle life of the battery cell is improved.

[0036] According to some embodiments of the present application, the cap plate assembly is disposed at both ends of the housing, and each of the cap plate assemblies includes at least two electrode terminals, thereby reducing the resistance of the battery cell and improving the current carrying capacity of the battery cell.

[0037] According to some embodiments of the present application, the cover plate assembly is arranged at both ends of the housing, each of the cover plate assemblies includes at least two electrode terminals, the two electrode terminals have opposite polarities, and the electrode terminals of the same polarity on the two cover plate assemblies are staggered along the length direction of the battery cell. As a result, the wiring can be reduced during the battery assembly process, reducing the difficulty of assembly.

[0038] 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 reducing assembly difficulty.

[0039] According to some embodiments of the present application, the positive electrode tab extends along the length direction of the positive electrode sheet or along its width direction; and / or the negative electrode tab extends along the length direction of the negative electrode sheet or along its width direction. Thus, the current transmission efficiency is improved, the resistance of the battery cell is reduced, and the rate performance of the battery is improved.

[0040] According to some embodiments of the present application, along a direction perpendicular to the thickness direction of the cover plate, the square cross section of the terminal body is a rounded rectangle, thereby improving the current carrying capacity of the electrode terminal when the cover plate area is small.

[0041] According to some embodiments of the present application, the charging time of the battery cell from 10% SOC to 80% SOC is 5 min - 10.5 min, optionally 7 min - 10 min. Thereby, the fast charging performance of the battery cell is improved.

[0042] The second aspect of the present application provides a battery device, including the battery cell provided by the first aspect of the present application, and the battery device is at least one of a battery module, a battery pack, and an energy storage device.

[0043] The third aspect of the present application provides an electrical device, including the battery cell provided by the first aspect of the present application or the battery device provided by the second aspect of the present application, and the battery cell or the battery device is used to provide electrical energy.

[0044] The additional aspects and advantages of the present application will be partly given in the following description, partly will become obvious from the following description, or be understood through the practice of the present application. Description of the Drawings

[0045] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present application. Moreover, in all the drawings, the same reference numerals are used to represent the same components. In the drawings: Figure 1 is a cross-sectional schematic diagram of a positive electrode plate in an embodiment of the present application. Figure 2 is a structural schematic diagram of a housing in an embodiment of the present application.

[0046] Figure 3 is a structural schematic diagram of a cover plate assembly in an embodiment of the present application.

[0047] Figure 4 is Figure 3 the exploded view of the cover plate assembly in

[0048] Figure 5 is Figure 4 the structural schematic diagram of another perspective of the cover plate assembly in

[0049] Figure 6 is Figure 5 the cross-sectional schematic diagram of the cover plate assembly along the AA' direction in

[0050] Figure 7 is a structural schematic diagram of another cover plate assembly in an embodiment of the present application.

[0051] Figure 8 is Figure 7 the exploded view of the cover plate assembly in

[0052] Figure 9 is Figure 7 a schematic structural view of another perspective of the cover plate assembly in

[0053] Figure 10 is Figure 9 a schematic cross-sectional view of the cover plate assembly in

[0054] Figure 11 a schematic structural view of a battery cell according to an embodiment of the present application.

[0055] Figure 12 a schematic structural view of a cover plate assembly according to another embodiment of the present application.

[0056] Figure 13 is Figure 12 an exploded view of the cover plate assembly in

[0057] Figure 14 is Figure 12 a schematic structural view of another perspective of the cover plate assembly in

[0058] Figure 15 is Figure 14 a schematic cross-sectional view of the cover plate assembly in

[0059] Figure 16 a schematic structural view of another cover plate assembly according to another embodiment of the present application.

[0060] Figure 17 is Figure 16 an exploded view of the cover plate assembly in

[0061] Figure 18 is Figure 16 a schematic structural view of another perspective of the cover plate assembly in

[0062] Figure 19 is Figure 18 a schematic cross-sectional view of the cover plate assembly in

[0063] Figure 20 a schematic structural view of an electrode assembly according to an embodiment of the present application.

[0064] Figure 21 a schematic structural view of an electrode assembly according to another embodiment of the present application.

[0065] Figure 22 a schematic structural view of an electrode assembly according to an embodiment of the present application.

[0066] Figure 23 a schematic structural view of a positive electrode plate according to an embodiment of the present application.

[0067] Figure 24It is a schematic structural diagram of a positive electrode tab of another embodiment of the present application.

[0068] Figure 25 It is a schematic structural diagram of a positive electrode tab of another embodiment of the present application.

[0069] Figure 26 It is a schematic structural diagram of a positive electrode tab of another embodiment of the present application.

[0070] Figure 27 It is a schematic structural diagram of a negative electrode tab of an embodiment of the present application.

[0071] Figure 28 It is a schematic structural diagram of a negative electrode tab of another embodiment of the present application.

[0072] Figure 29 It is a schematic structural diagram of a negative electrode tab of another embodiment of the present application.

[0073] Figure 30 It is a schematic structural diagram of a negative electrode tab of another embodiment of the present application.

[0074] Figure 31 It is a schematic structural diagram of a negative electrode tab of an embodiment of the present application.

[0075] Figure 32 It is a schematic diagram of an electrical device of the present application.

[0076] Explanation of reference numerals: 1 Battery cell; 11 Housing; 12 Cover assembly; 1213 First cover; 1214 Second cover; 1210 Through hole; 1211 Liquid injection hole; 1212 Pressure relief mechanism; 1221 Electrode terminal; 1222 First limiting part; 1223 Second limiting part; 1224 Terminal body; 1225 Riveting block; 123 First insulating part; 1230 Through hole; 124 Sealing part; 125 Positioning part; 126 Second insulating part; 10 Electrode assembly; 2 Positive electrode tab; 221 Lithium-containing phosphate; 222 Lithium supplement additive; 23 Positive electrode ear; 231 First positive electrode ear; 232 Second positive electrode ear; 3 Negative electrode tab; 30 Negative current collector; 31 Negative electrode film layer; 311 First negative electrode film layer; 312 Second negative electrode film layer; 32 Negative electrode ear; 321 First negative electrode ear; 322 Second negative electrode ear; 4 Separator film. Detailed implementation manners

[0077] The embodiments of the technical solutions of the present application will be described in detail below. The following embodiments are only used to illustrate the technical solutions of the present application more clearly, so they are only examples and cannot be used to limit the protection scope of the present application.

[0078] Reference to "embodiment" in this document means that the specific features, structures, or characteristics described in connection with the embodiment may be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0079] If there is no special instruction, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0080] If there is no special instruction, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0081] If there is no special instruction, all steps of the present application can be carried out in sequence or randomly, preferably in sequence. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out in sequence, or may also include steps (b) and (a) carried out in sequence. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or may also include steps (a), (c), and (b), or may also include steps (c), (a), and (b), etc.

[0082] Currently, judging from the development of the market situation, the application of batteries is becoming more and more extensive. Batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power, and solar power stations, but also widely used in electric transportation such as electric bicycles, electric motorcycles, and electric vehicles, as well as in multiple fields such as military equipment and aerospace. The battery cells in the related art cannot simultaneously meet the requirements of fast charging and long cycle life.

[0083] This application aims to propose a battery cell with excellent fast charging performance and high-temperature cycle life. For the battery cell proposed in this application, the positive electrode active material includes lithium-containing phosphate, and the negative electrode active material includes graphite. To further improve the fast charging ability of this battery cell, a chain carboxylic acid ester is introduced into the electrolyte to improve the wetting ability of the electrolyte in the positive electrode film layer containing lithium-containing phosphate and the negative electrode film layer containing graphite, which helps to improve the transport efficiency of lithium ions in the electrode film layer. At the same time, it can also increase the conductivity of lithium ions in the electrolyte, further improving the fast charging ability of the battery cell. However, with the increase in the conductivity of the electrolyte, the migration speed of lithium ions in the electrolyte is relatively fast, and the reaction rate at the phase interface increases accordingly. The intense reaction leads to uneven phase interface reactions, making the SEI film formed on the negative electrode unstable and constantly breaking and re-forming during the cycle. Especially in the case of high temperature, it further increases the gas generation of the battery cell and reduces the high-temperature cycle life of the battery cell. This application discovers that by adding at least one of an Fe-containing oxide or an Ni-containing oxide to the positive electrode film layer, the oxygen-containing substances released during the decomposition of the battery cell during the 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, enhancing the continuity of charge transfer, reducing the increase in impedance caused by the instability of the SEI film, and thus improving the high-temperature cycle life of the battery cell while improving the fast charging performance of the battery cell.

[0084] In the first aspect of this application, a battery cell is provided. The battery cell includes a positive electrode tab, and the positive electrode tab includes a positive electrode current collector and a positive electrode film layer provided on at least one side of the positive electrode current collector. Refer to Figure 1 , the positive electrode film layer includes lithium-containing phosphate 221 and a lithium supplement additive 222, and the lithium supplement additive 222 includes at least one of an Fe-containing oxide or an Ni-containing oxide; a negative electrode tab, the negative electrode tab includes a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector, and the negative electrode film layer includes graphite; an electrolyte, the electrolyte includes a chain carboxylic acid ester, and the conductivity of the electrolyte at room temperature is 10 mS / cm - 18 mS / cm.

[0085] Thus, for the battery cell proposed in this application, by introducing a chain carboxylic acid ester into the electrolyte, the fast charging ability of the battery cell is improved. On this basis, by adding at least one of an Fe-containing oxide or an Ni-containing oxide to the positive electrode film layer, the stability of the SEI film is improved, reducing the continuous breaking and re-forming of the SEI caused by the too high conductivity of the electrolyte, and improving the high-temperature cycle life of the battery cell.

[0086] In this application, the positive electrode sheet can be cut along its thickness direction by plasma to obtain the cross-section of the positive electrode sheet, and observed under a scanning electron microscope (SEM) at an appropriate magnification. The lithium-containing phosphate has an average particle size of 500μm - 800nm, and the iron-containing oxide or nickel-containing oxide has an average particle size of 10μm - 15μm.

[0087] As an example, the conductivity of the electrolyte at room temperature is 10mS / cm, 12mS / cm, 14mS / cm, 16mS / cm, 18mS / cm, etc., or can be in the range composed of any of the above values. Thereby, the ionic conductivity of the electrolyte is improved, and the rate performance of the battery cell is improved.

[0088] In this application, after disassembling the battery cell to obtain the electrolyte, a conductivity meter can be used to test the conductivity of the electrolyte at room temperature with reference to HG-T 4067-2015.

[0089] According to some embodiments of the present application, the iron-containing oxide or the nickel-containing oxide includes lithium and serves as a first lithium supplement additive to supplement the lithium ions in the battery cell. Specifically, the iron-containing oxide includes lithium or the nickel-containing oxide includes lithium, which can enable the first lithium supplement additive to act in the formation process or the cycling process of the battery cell and release active lithium ions to make up for the lithium ions consumed in the formation of the SEI film, thereby improving the cycle life and energy density of the battery cell.

[0090] According to some embodiments of the present application, the first lithium supplement additive includes at least one of lithium nickelate and lithium ferrite.

[0091] In some embodiments of the present application, the first lithium supplement additive may include Li e M1 f O g , where 1≤e≤6, 1≤f≤6, 2≤g≤12, and M1 may include one or more of Ni element, Co element, Mn element, and Fe element.

[0092] Exemplarily, the value of e can be 1, 2, 3, 4, 5, or 6, etc., or can be in the range composed of any of the above values. Optionally, the value of e can be 1<e≤6, such as 2≤e≤5.

[0093] The value of f can be 1, 2, 3, 4, 5, or 6, etc., or can be in the range composed of any of the above values.

[0094] The value of g can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, etc., or can be in the range composed of any of the above values. Optionally, the value of g can be 2≤g≤8.

[0095] Among them, Li e M1 f O g has a charging capacity that is 1 to 5 times that of the multi-component cathode active material, can provide additional lithium during the first charging process, and is also beneficial for pre-storing additional lithium at the negative electrode, extending the battery life. Incorporating Li e M1 f O g into the cathode film layer can achieve a good lithium compensation effect. It can be understood that during the battery formation and use processes, as the lithium compensation process progresses, the lithium in the first lithium compensation additive will be partially released or completely released, causing the first lithium compensation additive to change from the initial state to a partially delithiated state or a completely delithiated state. At this time, the situation of e≤1 and / or g≤2 will occur.

[0096] In some embodiments of the present application, the first lithium compensation additive may include, but is not limited to, Li 2 NiO 2 and / or Li 5 FeO 4 . In the manufacturing process of the cathode electrode, Li 2 NiO 2 and / or Li 5 FeO 4 can be directly incorporated into the cathode active material layer.

[0097] Li 2 NiO 2 can form LiNiO 2 with the ability to intercalate and deintercalate lithium after delithiation. LiNiO 2 can become Li 1-x NiO 2 in the delithiated state, where 0≤x≤1, and can be restored to LiNiO 2 in the lithiated state.

[0098] Li 5 FeO 4 has strong lithium compensation ability, and the LiFeO 2 formed after delithiation will not cause obvious side reactions. Thus, using Li 2 NiO 2 and / or Li 5 FeO 4 as the lithium compensator can achieve a good capacity compensation effect.

[0099] Exemplarily, the lithium compensator can be Li 2 NiO 2 , Li 2 NiO 2A considerable lithium replenishment capacity can be provided only by the valence change of Ni atoms at a lower potential, without the need to provide capacity through the valence change of oxygen atoms, which can reduce the risk of the electrolyte being oxidized by oxygen free radicals.

[0100] 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.

[0101] For example, the value of n may be 0, 0.5, 1, 1.5 or 2, or may be a range consisting of any of the above values.

[0102] 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.

[0103] 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.

[0104] The value of q can be 1, 2, 3 or 4, etc., or can be a range consisting of any of the above values.

[0105] For example, the initial state is Li 2 NiO 2 As an example of the first lithium supplement additive, when Li 2 NiO 2 When the lithium in the solution is partially released, the first lithium supplement Li n NiO m The composition may include one or more of the components of 0<n<1, n=1, 1<n<2; when Li 2 NiO 2 When the lithium in the body is completely removed, the first lithium supplement additive Li n NiO m The composition may include NiO m .

[0106] Taking the initial state as Li 5 FeO 4 As an example of the first lithium supplement additive, when Li 5 FeO 4 When the lithium in the solution is partially released, the first lithium supplement Li p FeO q The composition may include one or more of the components of 1<p<2, 2≤p<3, 3≤p<4, 4≤p<5; when Li5 FeO 4 When all the lithium in p FeO q is completely removed, the composition of the first lithium - supplement additive Li 2 FeO 2 may continue to have the possibility of lithium removal under factors such as polarization, resulting in the Li p FeO q component with p < 1.

[0107] In some embodiments of the present application, when the first lithium - supplement additive changes from the initial state to the completely lithium - removed 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.

[0108] For example, the value of m can be 0.5, 1, 1.5, 2, etc., or can be a range composed of any of the above - mentioned values.

[0109] The value of p can be 0.2, 0.5, 0.8, 1, etc., or can be a range composed of any of the above - mentioned values.

[0110] The value of q can be 0.2, 0.5, 1, 1.5, 2, etc., or can be a range composed of any of the above - mentioned values.

[0111] Exemplarily, taking the lithium - supplement agent in the initial state of Li 2 NiO 2 and Li 5 FeO 4 as an example, when the first lithium - supplement additive is completely lithium - removed, the separated first lithium - supplement additive may include, but is not limited to, NiO and / or LiFeO 2 , and the oxygen - containing substances released by its decomposition during the cycling process of the battery cell can participate in the film - forming reaction on the surface of the negative - electrode active material, thereby improving the stability of the SEI film, enhancing the continuity of charge transfer, reducing the increase in impedance caused by the instability of the SEI film, and thus improving the fast - charging performance of the battery cell while improving the high - temperature cycle life of the battery cell.

[0112] 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 C element, Al element, Zr element, P element, and S element. Qualitative analysis of the element types in the coating layer of the lithium - supplement additive can be carried out by means of characterization such as EDS energy - spectrum analysis. The air stability of the lithium - supplement agent is usually poor. Taking Li 2 NiO 2 as an example, it has strong alkalinity and is easy to react with water and CO2 The reaction forms a coating layer on the surface of the lithium supplement additive. On the one hand, it can improve its air stability and reduce the generation of lithium-containing impurities on the surface; on the other hand, it can also improve the ionic conductivity of the lithium supplement additive, improve the lithium-ion transport efficiency, enhance the kinetic performance, and thus further facilitate lithium deintercalation and improve the lithium supplement capacity.

[0113] 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 of analytical methods such as EDS energy spectrum analysis and X-ray diffraction. Among them, the lithium supplement additive has relatively poor conductivity. Using carbon materials, aluminum oxides, and zirconium oxides as the coating layer materials is beneficial to improving the air stability of the lithium supplement agent and reducing the generation of lithium-containing impurities on the surface. In addition, using carbon materials as the coating layer material is beneficial to improving the conductivity of the positive electrode sheet; using fast ion conductors, such as lithium phosphides or lithium sulfides (exemplarily, it can include lithium phosphate or lithium sulfate, etc.) as the coating layer materials is beneficial to improving the lithium-ion transport rate and enhancing the kinetic performance, and thus further facilitates lithium deintercalation and improves the lithium supplement capacity. This is beneficial to further improving the electrochemical performance of the battery.

[0114] In some embodiments of the present application, the first lithium supplement additive may further include doping elements, and the doping elements may include one or more of Al element, Zr element, and B element. Doping one or more of Al element, Zr element, and B element in the first lithium supplement additive is beneficial to reducing the decomposition voltage of the lithium supplement agent, enhancing the decomposition ability of the lithium supplement agent, enabling it to exert more capacity compensation, and is also beneficial to stabilizing the crystal structure after the decomposition of the lithium supplement agent, reducing the dissolution of transition metals and side reactions that may occur with the electrolyte, and thus further enabling the battery to have both high energy efficiency and cycle life.

[0115] In some embodiments of the present application, based on the total mass of the first lithium supplement additive, the contents of Al element, Zr element, and B element in the first lithium supplement additive can be independently 50 ppm - 1000 ppm, such as they can be independently 50 ppm, 200 ppm, 500 ppm, 800 ppm, or 1000 ppm, etc.

[0116] According to some embodiments of the present application, the lithium supplement additive further includes a second lithium supplement additive, and the second lithium supplement additive includes one or more of lithium nickel cobalt manganate, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganate, lithium tartrate, and lithium citrate.

[0117] In this application, by adding a first lithium supplement additive and a second lithium supplement additive to the positive electrode film layer at the same time, both lithium supplement additives can supplement lithium ions, make up for the irreversible loss of lithium ions in the system, and improve the capacity of the battery. In addition, the first lithium supplement additive can also release oxygen elements to participate in the formation of the SEI film, improve the stability of the SEI film, and improve the cycle life of the battery cell.

[0118] According to some embodiments of the present application, based on the total mass of the positive electrode film layer, the total mass ratio of the first lithium supplement additive and the second lithium supplement additive can be 0.1% - 5%. For example, it can be 0.1%, 1%, 2%, 3%, 4%, 5%, etc., or it can be a range composed of any of the above values. Thereby, the lithium supplement effect is improved, the capacity of the battery cell is increased, and the cycle life and energy density of the battery cell are improved.

[0119] In this application, one or more of conventional instruments and conventional methods such as a scanning electron microscope, an EDS energy spectrometer, an X-ray diffractometer, and an inductively coupled plasma emission spectrometer can be combined to perform qualitative analysis on the positive electrode film layer to determine whether there is a lithium supplement additive and its type in the positive electrode film layer. For example, in the positive electrode active material layer, in addition to the different elemental compositions, there are usually also differences in size and particle morphology between the lithium supplement additive and the positive electrode active material particles. Moreover, the lithium supplement additive will not completely disappear after de-lithiation, but will leave residual elements and particle skeletons. The lithium supplement additive usually undergoes a certain volume shrinkage after de-lithiation, forming a certain gap between the remaining particle skeletons and the surrounding area (refer to Figure 1 as shown, Figure 1It is a scanning electron microscope image of the cross-section of the positive electrode plate in a battery cell according to another embodiment of the present application, which shows the microscopic morphology of the lithium supplement additive (for example, lithium ferrite) with a coating layer after lithium deintercalation. A gap is formed between the particle skeleton and the coating layer on its surface during the late stage of lithium deintercalation of the lithium supplement additive. Based on the above differences, the possible positions of the lithium supplement additive in the cross-section of the positive electrode plate along its thickness direction can be quickly screened in the scanning electron microscope test, and the lithium supplement additive particles and the positive electrode active material particles can be distinguished by the elemental composition in combination with EDS energy spectrum analysis, and then the size differences between the particle sizes of the positive electrode active particles and the lithium supplement additive particles can be compared. For another example, the surface roughness of the positive electrode active material particles and the lithium supplement additive particles is usually also different, and the possible positions of the lithium supplement additive can be quickly screened in the scanning electron microscope test in combination with this difference. For another example, the lithium supplement additive usually does not completely deintercalate lithium after formation. The changes in the diffraction peaks (such as peak position, peak intensity, etc.) of the XRD pattern of the sample to be measured in the positive electrode active material layer before and after charge and discharge can be compared to pre-judge whether a lithium supplement additive is added to the positive electrode plate and the type of the added lithium supplement additive. In addition, due to the differences in the lithium content of the lithium supplement additive and the positive electrode active material itself and the different lithium deintercalation and intercalation efficiencies during charge and discharge, there are also differences in the lithium content of the electrode plate of the battery cell in the fully charged or fully discharged state. For example, in the charged state, the lithium deintercalation efficiency of the lithium supplement additive in the positive electrode plate 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) tests; and during one charge and discharge process, due to the differences in the lithium deintercalation and intercalation efficiencies of the lithium supplement additive and the positive electrode active material, there are obvious differences in the volume expansion between the material particles, which can be observed and characterized by in-situ confocal microscopy.

[0120] According to some embodiments of the present application, the lithium-containing phosphate includes a compound represented by Formula I: Li x A y Me a M2 b P 1-c X c Y z Formula I, Among them, 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.

[0121] As an example, x can be 0.5, 0.7, 0.9, 1.1, 1.3, etc., or can be a range composed of any of the above values.

[0122] As an example, y can be 0, 0.3, 0.6, 0.9, 1.1, 1.3, etc., or can be a range composed of any of the above values.

[0123] As an example, a can be 0.9, 1.1, 1.3, 1.5, etc., or can be a range composed of any of the above values.

[0124] As an example, b can be 0, 0.2, 0.4, 0.5, etc., or can be a range composed of any of the above values.

[0125] As an example, c can be 0, 0.2, 0.4, 0.5, etc., or can be a range composed of any of the above values.

[0126] As an example, z can be 3, 3.5, 4, 4.5, 5, etc., or can be a range composed of any of the above values.

[0127] According to some embodiments of the present application, the lithium-containing phosphate includes lithium iron phosphate material. Thus, the safety and cycle performance of the battery cell are improved.

[0128] According to some embodiments of the present application, the lithium-containing phosphate is granular, and the volume average particle size Dv50 of the lithium-containing phosphate is 1 µm - 2 µm. For example, it can be 1 µm, 1.2 µm, 1.4 µm, 1.6 µm, 1.8 µm, 2 µm, etc., or can be a range composed of any of the above values. Thus, the volume average particle size of the lithium-containing phosphate with an olivine structure is relatively small, which can shorten the migration path of lithium ions in the solid phase, reduce the polarization of the battery cell, reduce heat generation, and improve the high-temperature cycle performance of the battery cell.

[0129] In this application, Dv50 refers to the particle size corresponding to when the cumulative volume distribution percentage reaches 50%. For example, referring to the standard GB / T 19077-2016 / ISO 13320:2009, it is measured using a laser particle size analyzer (Malvern Master Size 2000). The specific test process is as follows: Scrape off the positive electrode film layer powder, calcine it at high temperature in an air atmosphere, grind it into powder, and after sieving, take an appropriate amount of the sample to be tested (the sample concentration only needs to ensure a light transmittance of 8%-12%), add deionized water, and at the same time perform ultrasonic dispersion to ensure that the sample is completely dispersed. Then, the sample is measured according to the standard GB / T19077-2016 / ISO 13320:2009.

[0130] According to some embodiments of the present application, the volume particle size Dv10 of the lithium-containing phosphate is 0.4 µm - 0.7 µm. For example, it can be 0.4 µm, 0.5 µm, 0.6 µm, 0.7 µm, etc., or it can be a range composed of any of the above values. Thus, the volume particle size Dv10 of the lithium-containing phosphate with an olivine structure is relatively small, which can shorten the migration path of lithium ions in the solid phase, reduce the polarization of the battery cell, reduce heat generation, and improve the high-temperature cycling performance of the battery cell.

[0131] In this application, Dv10 refers to the particle size corresponding to when the cumulative volume distribution percentage reaches 10%. For example, referring to the standard GB / T 19077-2016 / ISO 13320:2009, it is measured using a laser particle size analyzer (Malvern Master Size 2000). The specific test process is as follows: Scrape off the positive electrode film layer powder, calcine it at high temperature in an air atmosphere, grind it into powder, and after sieving, take an appropriate amount of the sample to be tested (the sample concentration only needs to ensure a light transmittance of 8%-12%), add deionized water, and at the same time perform ultrasonic dispersion to ensure that the sample is completely dispersed. Then, the sample is measured according to the standard GB / T19077-2016 / ISO 13320:2009.

[0132] According to some embodiments of the present application, the lithium-containing phosphate includes secondary particles, and the average particle size of the primary particles in the secondary particles is 200 nm - 500 nm. For example, it can be 200 nm, 300 nm, 400 nm, 500 nm, etc., or it can be a range composed of any of the above values. Thus, it can shorten the migration path of lithium ions in the solid phase, reduce the polarization of the battery cell, reduce heat generation, and improve the high-temperature performance of the battery cell.

[0133] In this application, the test method for the average particle size of primary particles is to use plasma to cut the positive electrode plate along its thickness direction to obtain the cross-section of the positive electrode plate, observe it under a scanning electron microscope (SEM) at an appropriate magnification, randomly select at least 50 primary particles, and the average particle size of a single primary particle = (the longest diameter of a single particle + the shortest diameter of a single particle) / 2. Taking the average value of the selected primary particles is the average particle size of the primary particles.

[0134] According to some embodiments of the present application, the battery cell further includes an electrolyte, and the electrolyte includes a chain carboxylic ester. Based on the total mass of the electrolyte, the mass ratio of the chain carboxylic ester can be 5% - 60%, for example, it can be 5%, 10%, 20%, 30%, 40%, 50%, 60%, etc., or it can be a range composed of any of the above values. When the content of the chain carboxylic ester is within the above range, on the one hand, the viscosity of the electrolyte can be reduced, the internal resistance of the battery cell can be reduced, the migration rate of lithium ions can be increased, and the fast charging performance of the battery cell can be improved; on the other hand, the risk of gas generation of the electrolyte under high temperature conditions can be reduced, and the high temperature cycle life of the battery cell can be improved, thereby obtaining a battery cell with both high energy density, excellent fast charging performance and high temperature cycle life. According to some specific embodiments of the present application, the mass ratio of the chain carboxylic ester can be 8% - 30%.

[0135] In this application, the test method for the content of the chain carboxylic ester is quantitative analysis of organic components by gas chromatography.

[0136] According to some embodiments of the present application, the chain carboxylic ester may include the compound shown in Formula II: Formula II, wherein, R 1 includes a hydrogen atom, C 1 -C 5 alkyl, C 1 -C 5 haloalkyl, or one or more of them, and R 2 includes C 1 -C 5 alkyl, C 1 -C 5 haloalkyl, or one or more of them.

[0137] Thus, when the mass percentage of the chain carboxylic ester shown in Formula I is 5%-60%, on the one hand, using the chain carboxylic ester with the above-mentioned content can improve the wetting ability of the electrolyte in the electrode film layer. Especially in a relatively long battery cell, it can improve the wetting uniformity of the electrolyte in the length direction of the electrode, enhance the electron transfer ability of the active material. In addition, it can also increase the migration rate of lithium ions in the electrolyte, thereby improving the fast charging performance of the battery cell. On the other hand, too high a content of carboxylic ester solvents also increases the gas generation inside the battery cell, which is not conducive to the cycling of the battery at high temperatures. Therefore, an appropriate amount of carboxylic ester solvents can also reduce the risk of gas generation of the electrolyte under high-temperature conditions and improve the high-temperature cycle life of the battery.

[0138] According to some embodiments of the present application, R 1 includes a hydrogen atom, C 1 -C 3 alkyl, C 1 -C 3 haloalkyl, or one or more of them. For example, R 1 may include a hydrogen atom, methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, or one or more of them. Thereby, the conductivity of the electrolyte is improved.

[0139] According to some embodiments of the present application, R 2 includes C 1 -C 3 alkyl, C 1 -C 3 haloalkyl, or one or more of them. For example, R 2 may be methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, or one or more of them. Thereby, the conductivity of the electrolyte is improved.

[0140] According to some embodiments of the present application, the chain carboxylic ester may include Formula II-1, Formula II-2, Formula II-3, Formula II-4, Formula II-5, Formula II-6, Formula II-7, Formula II-8, or one or more of them. Thereby, the above-mentioned types of chain carboxylic esters have a relatively small molecular weight and can improve the conductivity of the electrolyte.

[0141] According to some embodiments of the present application, the viscosity of the electrolyte at room temperature can be 1.5 mPa·s - 5.5 mPa·s. For example, it can be 1.5 mPa·s, 2.5 mPa·s, 3.5 mPa·s, 4.5 mPa·s, 5.5 mPa·s, etc., or can be a range composed of any of the above values. Thereby, 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.

[0142] In the present application, after disassembling the battery cell 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.

[0143] 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, it can be 1.05 g / mL, 1.15 g / mL, 1.25 g / mL, 1.35 g / mL, etc., or can be a range composed of any of the above values. Thereby, 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.

[0144] In the present application, after disassembling the battery cell to obtain the electrolyte, the density of the electrolyte is tested by a liquid densitometer. The density of the electrolyte at room temperature can be tested with reference to GB / T 2013-2010.

[0145] 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 -340 mg / 1540.25 mm 2 , for example, it can be 200 mg / 1540.25 mm 2 、230 mg / 1540.25 mm 2 、260 mg / 1540.25 mm 2 、290 mg / 1540.25 mm 2 、320 mg / 1540.25 mm 2 、340 mg / 1540.25 mm 2 etc., or can be a range composed of any of the above values. Thereby, 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 -300 mg / 1540.25 mm 2 .

[0146] The present application provides a method for testing the coating weight of the positive electrode film layer: disassemble the positive electrode sheet from the battery cell. 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), and punch it into small circular pieces with an area of S 1 and weigh it, record it as M 1 . Then wipe off the positive electrode film layer of the above-mentioned weighed positive electrode sheet, weigh the weight of the positive electrode current collector, and record it as M 0 . The single-sided coating weight of the positive electrode film layer = (M 1 - M 0 ) / S 1 .

[0147] According to some embodiments of the present application, the charging specific capacity of the lithium-containing phosphate at a rate of 0.1C is 150 mAh / g - 170 mAh / g. Thereby, the energy density of the battery cell is increased.

[0148] 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 - 2.8 g / cm 3 , for example, can be 2.5 g / cm 3 , 2.55 g / cm 3 , 2.6 g / cm 3 , 2.65 g / cm 3 , 2.7 g / cm 3 , 2.75 g / cm 3 , 2.8 g / cm 3 etc., or can be a range composed of any of the above values. Thereby, when the compaction density of the positive electrode film layer is within the above range, the stacking of the positive electrode sheet is relatively dense, which is beneficial to increasing the energy density of the battery cell, and 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.

[0149] The present application provides a method for testing the compaction density of the positive electrode film layer: charge at a constant current of 1 / 3C to 3.8V, charge at a constant voltage of 3.8V to 0.05C, disassemble the positive electrode sheet from the battery cell. 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), and punch it into small circular pieces with an area of S 1 and weigh it, record it as M 1 , measure its thickness H 1 . Then wipe off the positive electrode film layer of the above-mentioned weighed positive electrode sheet, weigh the weight of the positive electrode current collector, and record it as M 0 , measure its thickness H 0 . The single-sided coating weight of the positive electrode film layer = (M1 -M 0 ) / S 1 , the thickness of the positive electrode film = H 1 -H 0 , 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.

[0150] According to some embodiments of the present application, reference Figures 2 - 6 The battery cell includes a shell 11 and a cover assembly 12. The cover assembly 12 is disposed at at least one end of the shell 11. The shell 11 and the cover assembly 12 define a receiving cavity.

[0151] Specifically, the cover plate assembly 12 may be disposed at at least one end of the shell 11 along its length direction, or the cover plate assembly 12 may be disposed at at least one end of the shell 11 along its width direction.

[0152] As an example, refer to Figure 2 , the cover plate assembly 12 can be arranged at both ends of the shell 11 along its length direction; or the cover plate assembly 12 can be arranged at both ends of the shell 11 along its width direction. Specifically, when the shell 11 has openings at both ends along its length direction, the cover plate assembly 12 can be arranged at both ends of the shell 11 along its length direction and is suitable for covering the openings respectively; when the shell 11 has openings at both ends along its width direction, the cover plate assembly 12 can be arranged at both ends of the shell 11 along its width direction and is suitable for covering 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 shell 11 to match the shell 11.

[0153] 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.

[0154] According to some embodiments of the present application, 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 passes through the through hole and connects the first limiting portion and the second limiting portion, the first limiting portion is located on a side of the cover plate facing the accommodating cavity, and the second limiting portion is located on a side of the cover plate away from the accommodating cavity.

[0155] In some embodiments, the housing 11 is formed by bending and then splicing by welding, and the weld marks are integrated on the smaller side surface of the housing 11 extending along the length direction, which helps to reduce the problem of cracking of the welding area caused by the expansion of the battery cell along the thickness direction and improve the reliability of the housing 11.

[0156] Referring to Figures 3 - 6 , the cover assembly 12 includes a first cover 1213 and an electrode terminal 1221.

[0157] In some embodiments, referring to Figure 4 the disassembly schematic diagram of the cover assembly 12 of Figure 3 shown, the cover assembly 12 includes a first cover 1213, an electrode terminal 1221, a first insulating member 123, a sealing member 124, a second insulating member 126, a riveting block 1225, and a positioning member 125, and is assembled into

[0158] In some embodiments, Figure 6 is Figure 5 the cross-sectional schematic diagram of the cover assembly 12 of Figure 4 along the AA' direction. Combining Figure 6 it can be seen that a through hole 1210 is provided on the first cover 1213, the electrode terminal 1221 penetrates through the first cover 1213, a first insulating member 123 is provided between the first cover 1213 and the electrode terminal 1221. This assembly method is used to isolate the electrical connection components in the housing 11 from the first cover 1213 on the one hand, and at the same time make the electrode terminal 1221 and the first cover 1213 in an insulated state to reduce the risk of short circuit. A through hole 1230 is provided on the first insulating member 123, the electrode terminal 1221 sequentially passes through the through hole 1230 and the through hole 1210, and a sealing member 124 for insulation and sealing is provided between the through hole 1210 and the electrode terminal 1221. An opening is provided on the sealing member 124 so that the electrode terminal 1221 can pass through. A second insulating member 126 and a riveting block 1225 are provided on the side of the first cover 1213 away from the electrode assembly. Openings are also provided on the second insulating member 126 and the riveting block 1225, and the electrode terminal 1221 sequentially passes through the openings of the second insulating member 126 and the riveting block 1225. Among them, the second insulating member 126 is used to insulate the electrode terminal 1221 and the first cover 1213, and the riveting block 1225 is used to fix the electrode terminal 1221 on the first cover 1213.

[0159] In some embodiments, referring to Figure 4, the cover assembly 12 further includes positioning members 125, and there are at least two positioning members 125 to prevent the electrode terminals 1221 from deflecting and improve the stress strength of the electrode terminals 1221. In some embodiments, refer to Figure 5 , the cover assembly includes a liquid injection hole 1211 for injecting electrolyte into the accommodation cavity of the housing 11.

[0160] Refer to Figures 7 - 10 , the cover assembly 12 includes a second cover 1214 and electrode terminals 1221.

[0161] In some embodiments, refer to Figure 8 the disassembly schematic diagram of the cover assembly 12 in Figure 7 The cover assembly 12 shown.

[0162] In some embodiments, Figure 10 is Figure 9 the cross-sectional schematic diagram of the cover assembly in Figure 8 along the BB' direction. Combining Figure 10 and

[0163] In some embodiments, refer to Figure 8, the cover plate assembly 12 further includes positioning members 125. There are at least two positioning members 125 to prevent the electrode terminals 1221 from deflecting and improve the force-bearing strength of the electrode terminals 1221.

[0164] In this application, with reference to 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. Among them, along the direction perpendicular to the thickness direction of the cover plate, due to the limiting effect of the first limiting portion 1222 and the second limiting portion 1223, their cross-sectional area is larger than that of the terminal body 1224, and the cross-sectional area of the terminal body 1224 is usually smaller.

[0165] As an example, the cover plate can be made of a material with certain hardness and strength (such as aluminum alloy) to make the cover plate have higher strength. When the cover plate is squeezed, the deformation of the cover plate is reduced, and the safety performance of the battery cell is improved. In some embodiments, it can be a steel shell.

[0166] As an example, the cover plate and the housing 11 can be independent components.

[0167] As an example, the cover plate and the housing 11 can also be integrated. Specifically, at least one cover plate assembly 12 and the housing 11 can form a common connection body before the electrode assembly and other components are put into the housing. After the electrode assembly and other components are put into the housing 11, the cover plate assembly 12 is then used to cover the opening of the housing along its length direction (or width direction).

[0168] In this application, the first insulating member 123 and the second insulating member 126 can be independently plastics, rubbers, etc.

[0169] As an example, with reference to Figure 7 and Figure 8 , the cover plate assembly 12 further includes a pressure relief mechanism 1212. The pressure relief mechanism 1212 and the second cover plate 1214 are two separate components, and they are installed together after being separately formed. The pressure relief mechanism 1212 can be components such as an explosion-proof film, an explosion-proof valve, a safety valve, etc. The pressure relief mechanism 1212 can be installed on the cover plate by bonding, welding, etc. When the internal pressure of the battery cell reaches the threshold value, the pressure relief mechanism 1212 opens at least part of the pressure relief holes, and the discharge cut-off inside the battery cell is discharged through the pressure relief holes to relieve the internal pressure of the battery cell.

[0170] According to some embodiments of the present application, with reference to Figure 4 and Figure 8, along the direction perpendicular to the thickness direction of the cover plate, the cross-section of the terminal body 1224 is a rounded rectangle. Thus, when the area of the cover plate is small, the current-carrying capacity of the electrode terminal is improved.

[0171] According to some embodiments of the present application, the cover plate assemblies 12 are provided at both ends of the housing 11, and each cover plate assembly 12 includes at least two of the electrode terminals 1221. Specifically, the cover plate assemblies 12 can be provided at both ends of the housing 11 in the length direction or at both ends in the width direction, and each cover plate assembly 12 includes two electrode terminals 1221 with the same or opposite polarities. Thus, the resistance of the battery cell is reduced, and the current-carrying capacity of the battery cell is improved.

[0172] According to some embodiments of the present application, the cover plate assemblies are provided at both ends of the housing, each cover plate assembly includes at least two of the electrode terminals, the polarities of the two electrode terminals are opposite, and in the length direction of the battery cell, the electrode terminals with the same polarity on the two cover plate assemblies are arranged in a staggered manner.

[0173] According to some embodiments of the present application, the electrode terminals with the same polarity are arranged diagonally in the length direction of the battery cell.

[0174] Thus, during charging, the temperature rise of the battery cell can be reduced, and further the impedance of the battery cell can be reduced.

[0175] As an example, referring to Figure 11 , the cover plate assemblies 12 in the battery cell 1 are provided at both ends of the housing 11 in the length direction, and each cover plate assembly 12 includes two electrode terminals 1221 with opposite polarities.

[0176] Referring to Figures 12 - 15 , the cover plate assembly 12 includes a first cover plate 1213 and two electrode terminals 1221 with opposite polarities.

[0177] In some embodiments, referring to Figure 13 the disassembly schematic diagram of the cover plate assembly 12 in Figure 12 , the cover plate assembly includes a first cover plate 1213, two electrode terminals 1221, a first insulating member 123, two sealing members 124, two second insulating members 126, two riveting blocks 1225, and four positioning members 125, and are assembled into the cover plate assembly 12 shown in

[0178] In some embodiments, Figure 15 is Figure 14 the cross-sectional schematic diagram along the CC' direction. Combining Figure 13 and Figure 15It can be seen that two through holes 1210 are provided on the first cover plate 1213, and both of the electrode terminals 1221 penetrate through the first cover plate 1213. A first insulating member 123 is provided between the first cover plate 1213 and the two electrode terminals 1221. This assembly method is used on the one hand to isolate the electrical connection components in the housing 11 from the first cover plate 1213, and at the same time to insulate the electrode terminals 1221 from the first cover plate 1213 to reduce the risk of short circuit. Two through holes 1230 are provided on the first insulating member 123, and the two electrode terminals 1221 respectively pass through the through holes 1230 and the through holes 1210 in sequence. Sealing members 124 for insulation and sealing are provided between the through holes 1210 and the two electrode terminals 1221. The sealing members 124 are provided with openings so that the electrode terminals 1221 can pass through. On the side of the first cover plate 1213 away from the electrode assembly, two second insulating members 126 and two riveting blocks 1225 are provided. The second insulating members 126 and the riveting blocks 1225 are also provided with openings, and the electrode terminals 1221 pass through the openings of the second insulating members 126 and the riveting blocks 1225 in sequence. Among them, the second insulating member 126 is used to insulate the electrode terminals 1221 from the first cover plate 1213, and the two riveting blocks 1225 respectively fix the two electrode terminals 1221 on the first cover plate 1213. A liquid injection hole 1211 is provided on the first cover plate 1213 and can be used to inject electrolyte into the housing interior.

[0179] Reference Figures 16 - 19 , the cover plate assembly 12 includes a second cover plate 1214 and two electrode terminals 1221.

[0180] In some embodiments, referring to Figure 17 the disassembly schematic diagram of the cover plate assembly 12 of Figure 16 shown, the cover plate assembly 12 includes a second cover plate 1214, two electrode terminals 1221, a first insulating member 123, two sealing members 124, two second insulating members 126, two riveting blocks 1225, and four positioning members 125, and are assembled into

[0181] shown cover plate assembly 12. Figure 19 is Figure 18 the cross-sectional schematic diagram along the DD' direction. Combining Figure 17 and Figure 19It can be seen that two through holes 1210 are provided on the second cover plate, and the two electrode terminals 1221 respectively penetrate through the second cover plate 1214. A first insulating member 123 is provided between the second cover plate 1214 and the electrode terminals 1221. This assembly method is used, on the one hand, to isolate the electrical connection components in the housing 11 from the second cover plate 1214, and at the same time to insulate the electrode terminals 1221 from the second cover plate to reduce the risk of short circuit. Two through holes 1230 are provided on the first insulating member 123, and the two electrode terminals 1221 respectively pass through the correspondingly provided through holes 1230 and the through holes 1210. Sealing members 124 for insulation and sealing are provided between the through holes 1210 and the electrode terminals 1221. Openings are provided on the sealing members 124 to enable the electrode terminals 1221 to pass through. Two second insulating members 126 and two riveting blocks 1225 are provided on the side of the second cover plate 1214 away from the electrode assembly. Openings are also provided on the second insulating members 126. The electrode terminals 1221 sequentially pass through the openings on the second insulating members 126 and the riveting blocks 1225. Among them, the second insulating members 126 are used to insulate the electrode terminals 1221 from the second cover plate 1214, and the two riveting blocks 1225 are used to fix the two electrode terminals 1221 on the second cover plate 1214. A pressure relief mechanism 1212 is provided on the second cover plate 1214. When the internal pressure of the housing exceeds the threshold, the pressure relief mechanism 1212 can release the internal pressure of the housing.

[0182] Reference Figure 20 , the electrode assembly 10 includes four tab ears. Two tab ears extend from one end of the electrode assembly 10 in the length direction, which are the first positive tab ear 231 and the first negative tab ear 321 respectively. Two tab ears extend from the other end of the electrode assembly 10 in the length direction, which are the second positive tab ear 232 and the second negative tab ear 322 respectively. The first positive tab ear 231 is electrically connected to the positive terminal on the first cover plate, the first negative tab ear 321 is electrically connected to the negative terminal on the first cover plate, the second positive tab ear 232 is electrically connected to the positive terminal on the second cover plate, and the second negative tab ear 322 is electrically connected to the negative terminal on the second cover plate. Thus, the electrode terminals with different polarities are arranged diagonally in the length direction of the battery cell. During charging, the temperature rise of the battery cell can be reduced, and further the impedance of the battery cell can be reduced.

[0183] Reference Figure 21, the electrode assembly 10 includes four tab ears. At one end in the length direction of the electrode assembly 10, two tab ears extend out, namely the first positive tab ear 231 and the first negative tab ear 321. At the other end in the length direction of the electrode assembly 10, two tab ears extend out, namely the second positive tab ear 232 and the second negative tab ear 322. The first positive tab ear 231 is electrically connected to the positive terminal on the first cover plate, the first negative tab ear 321 is electrically connected to the negative terminal on the first cover plate, the second positive tab ear 232 is electrically connected to the positive terminal on the second cover plate, and the second negative tab ear 322 is electrically connected to the negative terminal on the second cover plate. That is, the electrode terminals on each cover plate are electrode terminals of different polarities, and there are a total of four electrode terminals on the battery cell. Thus, while improving the over-current capacity of the battery cell, problems such as unreasonable wire routing and too long wire harness caused by electrical connection between battery cells when multiple battery cells are assembled into a battery pack can be reduced, and it is easier to assemble.

[0184] According to some embodiments of the present application, referring to Figure 22 , the electrode assembly 10 further includes a negative electrode plate 3. The positive electrode plate 2 and the negative electrode plate 3 are stacked, and a separator 4 is provided between the positive electrode plate 2 and the negative electrode plate 3. A positive tab ear is provided on each layer of the positive electrode plate, and a negative tab ear is provided on each layer of the negative electrode plate. Thus, the current transmission efficiency is improved, the resistance of the battery cell is reduced, and the rate performance of the battery is improved.

[0185] According to some embodiments of the present application, the positive tab ear extends out along the length direction or the width direction of the positive electrode plate.

[0186] Referring to Figure 23 , only one tab ear extends out along the length direction of the positive electrode plate 2. Referring to Figure 24 , positive tab ears extend out at both ends along the length direction of the positive electrode plate 2.

[0187] Referring to Figure 25 , the positive tab ear 23 extends out from one end along the width direction of the positive electrode plate 2. At this time, the dimension of the positive tab ear 23 along the length direction of the positive electrode plate 2 can occupy 70%-90% of the total length of the positive electrode plate 2, so as to improve the over-current capacity of the battery cell.

[0188] In some embodiments, the electrical connection between the positive tab ear 23 and the electrode terminals on the two cover plate assemblies arranged along the length direction of the battery cell can be realized by welding an L-shaped adapter piece on the positive tab ear 23.

[0189] Referring to Figure 26 , the first positive tab ear 231 and the second positive tab ear 232 are respectively arranged on both sides of the positive electrode plate 2 along its width direction.

[0190] According to some embodiments of the present application, the negative electrode tab can extend from the negative electrode plate along its length direction or along its width direction. Thereby, the current transmission efficiency is improved, the resistance of the battery cell is reduced, and the rate performance of the battery is improved.

[0191] Reference Figure 27 , the negative electrode tab 32 extends out along the length direction of the negative electrode plate 3; Reference Figure 28 , the negative electrode tab extends out the first negative electrode tab 321 and the second negative electrode tab 322 respectively along the length direction of the negative electrode plate 3.

[0192] Reference Figure 29 , the negative electrode tab 32 extends out along the width direction of the negative electrode plate 3. At this time, the dimension 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, so as to improve the over-current capacity of the battery cell.

[0193] Reference Figure 30 , the first negative electrode tab 321 and the second negative electrode tab 322 are respectively arranged on both sides of the negative electrode plate along its width direction.

[0194] In some embodiments, the electrical connection between the negative electrode tab 32 and the electrode terminals on the two cover plate assemblies arranged along the length direction of the battery cell can be realized by welding an L-shaped adapter piece on the negative electrode tab 32.

[0195] In some embodiments, the battery cell of the present application is a stacked battery, the positive electrode plate and the negative electrode plate are stacked, a positive electrode tab is arranged on each layer of the positive electrode plate, and a negative electrode tab is arranged on each layer of the negative electrode plate.

[0196] In some embodiments, the positive electrode current collector can be made of a metal foil or a composite current collector. For example, as the metal foil, aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0197] In some embodiments, the positive electrode plate can be prepared in the following manner: the components for preparing the positive electrode plate, 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 processes such as drying and cold pressing, the positive electrode plate can be obtained.

[0198] According to some embodiments of the present application, the electrode assembly further includes a negative electrode tab, the negative electrode tab includes a negative current collector, and a negative electrode film layer is disposed on at least one side of the negative current collector. The compaction density of the negative electrode film layer corresponding to the battery cell at 100% SOC can be 1.15 g / cm 3 -1.36 g / cm 3 , for example, it can be 1.15 g / cm 3 , 1.2 g / cm 3 , 1.25 g / cm 3 , 1.3 g / cm 3 , 1.36 g / cm 3 , etc., or can be a range composed of any of the above values. According to some specific embodiments of the present application, the compaction density of the negative electrode film layer corresponding to the battery cell at 100% SOC can be 1.25 g / cm 3 -1.36 g / cm 3 . Thus, the energy density of the battery cell is increased.

[0199] The present application provides a method for testing the compaction density of a negative electrode film layer: charge at a constant current of 1 / 3C to 3.8V, charge at a constant voltage of 3.8V to 0.05C, disassemble the battery cell to obtain the negative electrode tab. For example, take a single-sided coated negative electrode tab (if it is a double-sided coated tab, the negative electrode film layer on one side can be wiped off first), punch it into small circular pieces with an area of S 2 , weigh it, and record it as M 3 , measure its thickness H 3 . Then wipe off the negative electrode film layer of the weighed negative electrode tab, weigh the negative current collector, and record it as M 2 , measure its thickness H 2 . The single-sided coating weight of the negative electrode film layer = (M 3 - M 2 ) / S 2 , the thickness of the negative electrode film layer = H 3 - H 2 , 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.

[0200] According to some embodiments of the present application, the single-sided coating weight of the negative electrode film layer can be 90 mg / 1540.25 mm 2 -170 mg / 1540.25 mm 2 , for example, it can be 90 mg / 1540.25 mm 2 , 110 mg / 1540.25 mm 2 , 130 mg / 1540.25 mm 2 , 150 mg / 1540.25 mm 2, 170 mg / 1540.25 mm 2 etc., or can be a range composed of any of the above values. According to some specific embodiments of the present application, the single-sided coating weight of the negative electrode film layer can be 110 mg / 1540.25 mm 2 -150 mg / 1540.25 mm 2 . Thereby, the energy density of the battery cell is increased.

[0201] The present application provides a method for testing the coating weight of the negative electrode film layer: disassemble the negative electrode sheet from the battery cell. For example, take the 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 round pieces with an area of S 2 , weigh it, and record it as M 3 . Then wipe off the negative electrode film layer of the above-mentioned weighed negative electrode sheet, weigh the weight of the negative electrode current collector, and record it as M 2 . The single-sided coating weight of the negative electrode film layer = (M 3 - M 2 ) / S 2 .

[0202] According to some embodiments of the present application, the negative electrode film layer includes a negative electrode active material, and the charging gram capacity of the negative electrode active material at a 0.1C rate is 350 mAh / g - 480 mAh / g. For example, it can be 350 mAh / g, 370 mAh / g, 390 mAh / g, 410 mAh / g, 430 mAh / g, 450 mAh / g, 480 mAh / g, etc., or can be a range composed of any of the above values. Thereby, the energy density of the battery cell is increased.

[0203] According to some embodiments of the present application, referring to 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 disposed on at least one side of the negative electrode current collector 30, and the second negative electrode film layer 312 is disposed on the side of the first negative electrode film layer 311 facing away from the negative electrode current collector 30. The first negative electrode film layer 311 includes first graphite particles, and the second negative electrode film layer 312 includes second graphite particles. The volume average particle size of the first graphite particles is greater than the volume average particle size of the second graphite particles. During the fast charging process, the overpotential of the second negative electrode film layer 312 is usually relatively high. By making the volume average particle size of the second graphite particles smaller, the solid-phase transmission path of lithium ions can be shortened, the diffusion rate of lithium ions can be increased, the fast charging performance can be improved, and at the same time, the problem of lithium metal deposition on the negative electrode surface can be improved.

[0204] According to some embodiments of the present application, the first graphite particles include natural graphite. Thereby, the compaction density of the negative electrode sheet is increased.

[0205] According to some embodiments of the present application, the volume average particle size Dv50 of the first graphite particles may be 7 µm - 18.5 µm. For example, it may be 7 µm, 11 µm, 13 µm, 15 µm, 17 µm, 18.5 µm, etc., or may be a range composed of any of the above values.

[0206] According to some embodiments of the present application, the volume average particle size Dv50 of the second graphite particles may be 7 µm - 14.3 µm. For example, it may be 7 µm, 9 µm, 11 µm, 13 µm, 14.3 µm, etc., or may be a range composed of any of the above values. Thus, the volume average particle size of the second graphite particles is smaller, which can shorten the solid-phase transmission path of lithium ions and improve the fast charging performance of the battery cell.

[0207] According to some embodiments of the present application, the first negative electrode film layer and the second negative electrode film layer each independently include a silicon-based material. Based on the total mass of the negative electrode film layer, the mass proportion of silicon element may be 0.3% - 10%. For example, it may be 0.3%, 1%, 3%, 5%, 7%, 9%, 10%, etc., or may be a range composed of any of the above values. Thus, the capacity of the negative electrode active material is increased, and the energy density of the battery cell is improved.

[0208] In the present application, the content of silicon element can be tested by inductively coupled plasma optical emission spectrometry ICP-OES.

[0209] According to some embodiments of the present application, the thickness of the negative electrode current collector is 4 µm - 8.5 µm. For example, it may be 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 8.5 µm, etc., or may be a range composed of any of the above values. Thus, on the basis of reducing the occupied space inside the housing 11, the current-carrying capacity of the negative electrode current collector is improved.

[0210] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil can be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0211] In some embodiments, the negative electrode sheet can be prepared in the following manner: 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 processes such as drying and cold pressing, the negative electrode sheet can be obtained.

[0212] According to some embodiments of the present application, the charging time of the battery cell configured to charge from 10% SOC to 80% SOC is 5 min - 10.5 min. For example, it can be 5 min, 7 min, 9 min, 10.5 min, etc., or it can be a range composed of any of the above values. Thereby, the fast charging performance of the battery cell is improved. According to some specific embodiments of the present application, the charging time of the battery cell configured to charge from 10% SOC to 80% SOC is 7 min - 10 min.

[0213] In some embodiments, the battery further includes a separator. The present application does not particularly limit the type of the separator, and any well-known porous structure separator with good chemical stability and mechanical stability can be selected.

[0214] 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.

[0215] The second aspect of the present application provides a battery device, including the battery cell provided in the first aspect of the present application, and the battery device is at least one of a battery module, a battery pack, and an energy storage device.

[0216] The third aspect of the present application provides an electrical device, including 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, and the battery cell or the battery device is used to provide electrical energy.

[0217] The electrical device can include mobile devices (such as mobile phones, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto.

[0218] As the electrical device, the battery device can be selected according to its usage requirements.

[0219] Figure 32It is an electrical device as an example. The electrical device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the electrical device for the battery, a battery pack or a battery module can be adopted.

[0220] The device as another example can be a mobile phone, a tablet computer, a laptop computer, etc. The device usually requires being thin and light, and a battery cell can be adopted as the power source.

[0221] To make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail in combination with the embodiments and the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way constitutes a limitation to the present application and its application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the present application.

[0222] Embodiment 1 1. Positive electrode plate The positive electrode plate includes a positive current collector aluminum foil, and positive electrode film layers are provided on two surfaces of the aluminum foil. In the state of 100% SOC, the compaction density is 2.6 g / cm 3 , and the coating weight of the single-sided positive electrode film layer is 280 mg / 1540.25 mm 2 . Based on the total mass of the single-sided positive electrode film layer, the positive electrode film layer includes a lithium iron phosphate material accounting for 94% by mass, a first lithium supplement additive lithium ferrite accounting for 2%, a second lithium supplement additive lithium titanate accounting for 1%, a conductive agent carbon black accounting for 1%, and a binder polyvinylidene fluoride (PVDF) accounting for 2%. 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, the volume particle size Dv10 is 0.45 μm, and the lithium iron phosphate surface has a carbon coating layer. Based on the total mass of the lithium iron phosphate, the mass ratio of the carbon coating layer is 1.18%.

[0223] 2. Negative electrode plate The negative electrode plate includes a negative current collector copper foil, and negative electrode film layers are provided on two surfaces of the copper foil. The negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer. The mass ratio of the graphite active material, the conductive agent carbon black, the binder styrene-butadiene rubber, and the thickener sodium carboxymethylcellulose in the first negative electrode film layer is 96.5:0.5:2:1. The mass ratio of the graphite active material, the conductive agent carbon black, the binder styrene-butadiene rubber, and the thickener sodium carboxymethylcellulose in the second negative electrode film layer is 97.5:0.5:1:1. In the state of 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 layer is 130 mg / 1540.25 cm 2 .

[0224] 3. Electrolyte The electrolyte includes a chain carboxylic acid ester, a cyclic carbonate solvent, an electrolyte salt, and an additive. The chain carboxylic acid ester 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, the mass ratio of II-1 is 5%, the mass ratio of EC is 72%, the mass ratio of lithium hexafluorophosphate is 15%, and the mass ratio of VC is 8%. The conductivity of the electrolyte is 9.5 mS / cm, the viscosity of the electrolyte is 3.2 mPa·s, and the density of the electrolyte is 1.22 g / mL.

[0225] 4. Separator Polyethylene film with a thickness of 7 μm.

[0226] 5. Battery cell The battery cell includes a housing, a cover plate assembly, an electrode assembly, and an electrolyte. The cover plate assemblies are located at both ends of the housing in the length direction. The structure of one cover plate assembly refers to Figure 2 , and the structure of the other cover plate assembly refers to Figure 6 , that is, one cover plate assembly includes a positive terminal, and the other cover plate assembly includes a negative terminal. The electrode assembly and the electrolyte are arranged in the accommodation cavity formed by the housing and the cover plate assembly. The electrode assembly is a laminated electrode assembly, which is made by laminating the above-mentioned positive electrode plate, separator, and negative electrode plate. Along the length direction of the electrode assembly, a positive electrode tab extends from one end, and a negative electrode tab extends from one end. The positive electrode tab is electrically connected to the positive terminal, and the negative electrode tab is electrically connected to the negative terminal.

[0227] Performance test 1. DCR The battery cell is charged at a constant current of 0.33C to 3.8V at 25°C, charged at a constant voltage to 0.05C, left standing for 30 min, and discharged at a constant current of 0.33C to 2.0V. At this time, the discharge capacity is A 0 , in units of Ah, left standing for 30 min, charged at a constant current of 0.33C to 3.8V, charged at a constant voltage to 0.05C, and discharged at a constant current of 0.33C for 0.5A 0 , adjust the SOC of the battery cell, left standing for 120 min, and record the voltage in the last 1 s as V 0 , in units of V, 4A 0 Discharge at a constant current (in units of A) for 30 s, and the discharge end voltage is V 1 , in units of V, 30s DCR = (V 0 -V 1 ) / 4A 0×1000, unit: mΩ.

[0228] 2. High-temperature cycle life At an ambient temperature of 45°C, the battery cell is charged to 3.8V by Step charge, then charged at a constant voltage until 0.05C, left to stand for 30 min, discharged at a constant current of 0.5C until 2.5V, and left to stand for 30 min. This is one charge-discharge cycle. Repeat the above charge-discharge cycle until the capacity of the battery cell is 80% of the initial capacity. The number of charge-discharge cycles obtained is the high-temperature cycle life of the battery cell.

[0229] The steps of Step charge are as follows: Charge at a constant current of 1C from 0% SOC to 10% SOC; Charge at a constant current of 7.0C from 10% SOC to 30% SOC; Charge at a constant current of 6.2C from 30% SOC to 35% SOC; Charge at a constant current of 5.7C from 35% SOC to 40% SOC; Charge at a constant current of 5.2C from 40% SOC to 45% SOC; Charge at a constant current of 4.8C from 45% SOC to 50% SOC; Charge at a constant current of 4.6C from 50% SOC to 55% SOC; Charge at a constant current of 4.4C from 55% SOC to 60% SOC; Charge at a constant current of 4.2C from 60% SOC to 65% SOC; Charge at a constant current of 3.9C from 65% SOC to 70% SOC; Charge at a constant current of 3.5C from 70% SOC to 75% SOC; Charge at a constant current of 3.0C from 75% SOC to 80% SOC; Charge at a constant current of 0.33C from 80% SOC to 100% SOC.

[0230] 3. Charging time Calculate the time for the battery cell to be charged from 10% SOC to 80% SOC. The specific charging process is as follows: Charge from 0% SOC to 10% SOC at a constant current of 1C; charge from 10% SOC to 30% SOC at a constant current of 7.0C; charge from 30% SOC to 35% SOC at a constant current of 6.2C; charge from 35% SOC to 40% SOC at a constant current of 5.7C; charge from 40% SOC to 45% SOC at a constant current of 5.2C; charge from 45% SOC to 50% SOC at a constant current of 4.8C; charge from 50% SOC to 55% SOC at a constant current of 4.6C; charge from 55% SOC to 60% SOC at a constant current of 4.4C; charge from 60% SOC to 65% SOC at a constant current of 4.2C; charge from 65% SOC to 70% SOC at a constant current of 3.9C; charge from 70% SOC to 75% SOC at a constant current of 3.5C; charge from 75% SOC to 80% SOC at a constant current of 3.0C. The sum of the charging times for each segment is the total charging time.

[0231] Example 2 The preparation method of the battery cell is the same as that of Example 1, except that the mass ratio of II-1 is 10% and the mass ratio of EC is 67%.

[0232] Example 3 The preparation method of the battery cell is the same as that of Example 1, except that the mass ratio of II-1 is 30% and the mass ratio of EC is 47%.

[0233] Example 4 The preparation method of the battery cell is the same as that of Example 1, except that the mass ratio of II-1 is 60% and the mass ratio of EC is 17%.

[0234] Comparative Example 1 The preparation method of the battery cell is the same as that of Example 1, except that the mass ratio of II-1 is 3% and the mass ratio of EC is 74%.

[0235] Comparative Example 2 The preparation method of the battery cell is the same as that of Example 1, except that the mass ratio of II-1 is 65% and the mass ratio of EC is 12%.

[0236] Comparative Example 3 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% by mass of conductive agent carbon black, and 2% by mass of binder PVDF.

[0237] The specific differences and test results of the battery cells in Examples 1 - 4 and Comparative Examples 1 - 3 are shown in Table 1.

[0238]

[0239] It can be seen from the comparison between Examples 1 - 4 and Comparative Examples 1 - 3 that by adding chain carboxylic esters to the electrolyte, the ionic conductivity of the electrolyte can be increased, the DCR of the battery cell can be reduced, and the fast charging performance of the battery cell can be improved. As the content of the chain carboxylic ester increases, the reaction rate at the phase interface increases correspondingly, the stability of the SEI film decreases, and the high-temperature cycle life of the battery cell gradually decreases. It can be seen from Example 2 and Comparative Example 3 that by adding lithium ferrite and lithium titanate to the positive electrode plate, a battery cell with a lower DCR and a higher high-temperature cycle life can be obtained. It 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 enhanced, the increase in impedance caused by the instability of the SEI film can be reduced, and thus while improving the fast charging performance of the battery cell, the high-temperature cycle life of the battery cell can be improved.

[0240] Example 5 The preparation method of the battery cell is the same as that of Example 2, except that the mass ratio of lithium ferrite is 0.1%, the positive electrode film layer does not contain lithium titanate, and the mass ratio of the lithium iron phosphate material is 96.9%.

[0241] Example 6 The preparation method of the battery cell is the same as that of Example 2, except that the mass ratio of lithium ferrite is 2%, the positive electrode film layer does not contain lithium titanate, and the mass ratio of the lithium iron phosphate material is 95%.

[0242] Example 7 The preparation method of the battery cell is the same as that of Example 2, except that the mass ratio of lithium ferrite is 5%, the positive electrode film layer does not contain lithium titanate, and the mass ratio of the lithium iron phosphate material is 92%.

[0243] Example 8 The preparation method of the battery cell is the same as that of Example 2, except that the mass ratio of lithium ferrite is 5.5%, the positive electrode film layer does not contain lithium titanate, and the mass ratio of the lithium iron phosphate material is 91.5%.

[0244] Example 9 The preparation method of the battery cell is the same as that of Example 2, except that the mass ratio of lithium ferrite is 0.05%, the mass ratio of lithium titanate is 0.05%, and the mass ratio of the lithium iron phosphate material is 96.9%.

[0245] Example 10 The preparation method of the battery cell is the same as that of Example 2, except that the mass ratio of lithium ferrite is 1%, the mass ratio of lithium titanate is 1%, and the mass ratio of the lithium iron phosphate material is 93%.

[0246] Example 11 The preparation method of the battery cell is the same as that of Example 2, except that the mass ratio of lithium ferrite is 3.5%, the mass ratio of lithium titanate is 1.5%, and the mass ratio of the lithium iron phosphate material is 92%.

[0247] Example 12 The preparation method of the battery cell is the same as that of Example 2, except that the mass ratio of lithium ferrite is 3.5%, the mass ratio of lithium titanate is 2%, and the mass ratio of the lithium iron phosphate material is 91.5%.

[0248] The specific differences and test results of the battery cells in Comparative Example 3 and Examples 5 - 12 are shown in Table 2.

[0249] Table 2

[0250] It can be seen from the comparison between Examples 5 - 12 and Comparative Example 3 that by adding a lithium supplement additive to the positive electrode film layer, the cycle life of the battery cell can be improved.

[0251] It can be seen from Examples 5 - 12 that when the positive electrode film layer contains both the first lithium supplement additive and the second lithium supplement additive, compared with adding only the first lithium supplement additive, the DCR of the battery cell can be further reduced and the high-temperature cycle life of the battery cell can be improved. That is, while the first lithium supplement additive improves the stability of the SEI film and supplements lithium, the second lithium supplement additive can further exert the lithium supplement effect and improve the high-temperature cycle life of the battery cell.

[0252] Example 13 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 .

[0253] Example 14 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 .

[0254] Example 15 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 .

[0255] Example 16 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 .

[0256] Example 17 The preparation method of the battery cell is the same as that of Example 2, except that at the state of 100% SOC, the tap density of the positive electrode film layer is 2.5 g / cm 3 .

[0257] Example 18 The preparation method of the battery cell is the same as that of Example 2, except that at the state of 100% SOC, the tap density of the positive electrode film layer is 2.8 g / cm 3 .

[0258] The detailed differences and test results of the battery cells in Examples 13 - 18 are shown in Table 3.

[0259] Table 3

[0260] It can be seen from Examples 13 - 18 that by adjusting the coating weight and tap 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 both excellent fast charging performance and cycle performance.

[0261] Example 19 The preparation method of the battery cell is the same as that of Example 2, except that the chain carboxylic ester is II - 2.

[0262] Example 20 The preparation method of the battery cell is the same as that of Example 2, except that the chain carboxylic ester is II - 3.

[0263] Example 21 The preparation method of the battery cell is the same as that of Example 2, except that the chain carboxylic ester is II - 5.

[0264] Example 22 The preparation method of the battery cell is the same as that of Example 2, except that the chain carboxylic ester is II - 7.

[0265] Example 23 The preparation method of the battery cell is the same as that of Example 2, except that the chain carboxylic ester is II - 8.

[0266] The detailed differences and test results of the battery cells in Examples 19 - 23 are shown in Table 4.

[0267] Table 4

[0268] It can be seen from Examples 19 - 23 that by selecting different types of chain carboxylic esters, electrolytes with higher conductivity can be obtained, thereby reducing the resistance of the battery cell and improving the fast charging performance of the battery cell.

[0269] 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 foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered by the scope of the claims and the specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, wherein: include: A positive electrode sheet, the positive electrode sheet 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 carboxylic acid ester and has an electrical conductivity of 10 mS / cm-18 mS / cm at room temperature.

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 element, Co element, Mn element, and Fe element.

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 part 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 C element, the Al element, the Zr element, the P element, and the S element.

9. The battery cell according to claim 8, wherein: The coating layer includes one or more of carbon material, 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 element, Zr element, and B element.

11. The battery cell according to claim 10, wherein: Based on the total mass of the first lithium supplementing additive, the contents of the Al element, the Zr element, and the B element in the first lithium supplementing additive are independently 50 ppm-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: Among them, 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 5%-60%.

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

21. 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.

22. 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.

23. The battery cell according to claim 22, 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.

24. The battery cell according to claim 23, 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.

25. The battery cell according to claim 23 or 24, 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.

26. 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 .

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

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

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

30. 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.

31. 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. The cover plate is provided with a through hole, 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 a side of the cover plate facing the accommodating cavity, and the second limiting portion is located on a side of the cover plate away from the accommodating cavity.

32. The battery cell according to claim 31, 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.

33. The battery cell according to claim 31, wherein: The cover plate assemblies are arranged at both ends of the shell, and each of the cover plate assemblies includes at least two electrode terminals, the two electrode terminals have opposite polarities, and the electrode terminals of the same polarity on the two cover plate assemblies are staggered along the length direction of the battery cell.

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

35. The battery cell according to claim 30, wherein: The positive electrode tab extends along the length direction of the positive electrode sheet or along the width direction thereof; and / or The negative electrode tab extends along the length direction of the negative electrode sheet or along the width direction thereof.

36. The battery cell according to claim 31, wherein: Along a direction perpendicular to the thickness direction of the cover plate, a cross section of the terminal body is a rounded rectangle.

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

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

39. A battery device, wherein: Comprising the battery monomer described in any one of claims 1-38, the battery device is at least one of a battery module, a battery pack, and an energy storage device.

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

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