Battery cell, battery device and electric device

Abstract

The invention provides a battery monomer, a battery device and a power utilization device. The battery monomer comprises an electrode assembly, the electrode assembly comprises a positive pole piece, the positive pole piece comprises a positive pole current collector and a positive pole active layer arranged on at least one side of the positive pole current collector, the positive pole active layer comprises a positive pole active material, and the positive pole active material comprises a lithium iron manganese phosphate positive pole material and a lithium-containing nickel cobalt manganese oxide positive pole material; in the lithium-containing nickel-cobalt-manganese oxide positive electrode material, the element Ni accounts for 50%-95% of the total molar weight of the three elements Ni, Co and Mn, and the lithium-containing nickel-cobalt-manganese oxide positive electrode material accounts for 5%-95% of the positive electrode active material; in the lithium manganese iron phosphate positive electrode material, the Mn element accounts for 30-80% of the total molar weight of the Mn element and the Fe element, and the discharge voltage platform of a battery monomer at normal temperature and at the rate of 0.1 C is 3.29-4.15 V.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell, a battery device and an electrical device. Background Art

[0002] With the popularization and development of electric vehicles, the performance requirements for battery cells are gradually increasing. At present, they not only need to have high energy density to reduce users' mileage anxiety, but also need to have high cycle stability to improve battery life and safety performance.

[0003] Lithium iron phosphate batteries are widely used as power batteries in electric vehicles due to their low cost. The iron phosphate-based positive electrode materials have obvious cost advantages over ternary positive electrode materials. However, the energy density of iron phosphate-based positive electrode materials is relatively low, so it is necessary to improve the energy density of the battery system while maintaining the low cost advantage. Summary of the invention

[0004] The present application provides a battery cell, a battery device and an electrical device, which improve the energy density of the battery cell.

[0005] The first aspect of the present application provides a battery cell, including an electrode assembly, the electrode assembly including a positive electrode sheet, a negative electrode sheet, and a separator located between the positive electrode sheet and the negative electrode sheet, wherein the negative electrode sheet includes a negative electrode current collector and a negative electrode active layer arranged on at least one side of the negative electrode current collector, the negative electrode active layer includes a negative electrode active material, the negative electrode active material includes one or more of a carbon-based material and a silicon-based material, the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer arranged on at least one side of the positive electrode current collector, the positive electrode active layer includes a positive electrode active material, the positive electrode active material The materials include lithium iron manganese phosphate positive electrode material and lithium-containing nickel cobalt manganese oxide positive electrode material. In the lithium-containing nickel cobalt manganese oxide positive electrode material, the Ni element accounts for 50% to 95% of the total molar amount of the three elements Ni, Co, and Mn, and the lithium-containing nickel cobalt manganese oxide positive electrode material accounts for 5%-95% of the positive electrode active material; in the lithium iron manganese phosphate positive electrode material, the Mn element accounts for 30%-80% of the total molar amount of the Mn element and the Fe element, and the discharge voltage platform of the battery cell at room temperature and a rate of 0.1C is 3.29V-4.15V.

[0006] The positive electrode active materials of the battery cell of the present application include lithium iron manganese phosphate positive electrode material and lithium-containing nickel cobalt manganese oxide positive electrode material, wherein the Mn element content of the lithium iron manganese phosphate positive electrode material is positively correlated with the voltage platform of the mixed positive electrode material, but is negatively correlated with the gram capacity of the lithium iron manganese phosphate positive electrode material, and is not conducive to the skeleton stability of the lithium iron manganese phosphate positive electrode material in long-term circulation; while the Ni element content in the lithium-containing nickel cobalt manganese oxide positive electrode material is positively correlated with the voltage platform and gram capacity of the mixed positive electrode material, but is not conducive to the skeleton stability of the lithium-containing nickel cobalt manganese oxide in long-term circulation.

[0007] This application is based on the actual needs of customers for low cost, high specific energy and long cycle, and it is found that by making the Ni element in the lithium-containing nickel cobalt manganese oxide positive electrode material account for 50% to 95% of the total molar amount of the three elements Ni, Co and Mn, and the lithium-containing nickel cobalt manganese oxide positive electrode material accounts for 5%-95% of the positive electrode active material; further by making the Mn element in the lithium iron manganese phosphate positive electrode material account for 30%-80% of the total molar amount of the Mn element and the Fe element, the gram capacity of the mixed positive electrode material is better, and the voltage platform is maintained in an appropriate range, so that the battery cell has both low cost, energy density and high cycle performance.

[0008] At the same time, the lithium iron manganese phosphate positive electrode material has an olivine structure, which is more stable and low-cost than the layered structure of the lithium-containing nickel cobalt manganese oxide positive electrode material. The battery cell using a mixed positive electrode material of lithium iron manganese phosphate positive electrode material and lithium-containing nickel cobalt manganese oxide positive electrode material has improved cycle stability, safety and power performance compared to the battery cell of pure lithium-containing nickel cobalt manganese oxide positive electrode material, and the cost is greatly reduced compared to the lithium-containing nickel cobalt manganese oxide positive electrode material.

[0009] In any embodiment of the first aspect, the voltage platform of the battery cell at room temperature and a rate of 0.1C is 3.67V-3.86V.

[0010] In any embodiment of the first aspect, in the lithium-containing nickel-cobalt-manganese oxide positive electrode material, the molar content of the Ni element relative to the total molar number of the nickel-cobalt-manganese elements is 80%-95%.

[0011] In any embodiment of the first aspect, in the lithium manganese iron phosphate positive electrode material, the molar content of the Mn element relative to the total molar number of the Mn element and the Fe element is 50%-70%.

[0012] In any embodiment of the first aspect, based on the total mass of the positive electrode active material, the mass content of the lithium iron manganese phosphate positive electrode material is 50%-95%, and can further be 50%-70%.

[0013] In any embodiment of the first aspect, the surface density of the positive electrode active layer is 200 mg / 1540.25 mm 2 -370mg / 1540.25mm 2 , optional: 240mg / 1540.25mm 2 -340mg / 1540.25mm 2 .

[0014] In any embodiment of the first aspect, the surface capacity of the positive electrode sheet is 50 mAh / 1540.25 mm 2 -350mAh / 1540.25mm 2 , optional 80mAh / 1540.25mm 2 -150mAh / 1540.25mm 2 .

[0015] In any embodiment of the first aspect, the compaction density of the positive electrode active layer corresponding to the battery cell at 100% SOC is 2.45 g / cm 3 -3.4g / cm 3 , optional 2.5g / cm 3 -3.2g / cm 3 .

[0016] In any embodiment of the first aspect, the powder compaction density of the positive electrode active material at 30000N is ≥2.43 g / cm 3 , can be selected as ≥2.45g / cm 3 , optional 2.45g / cm 3 -3.0g / cm 3 .

[0017] In any embodiment of the first aspect, the lithium-containing nickel cobalt manganese oxide positive electrode material further contains one or more of the elements Zr, Al, B, Fe, Ca, Sr, Ti, V or Y.

[0018] In any embodiment of the first aspect, the lithium-containing nickel cobalt manganese oxide positive electrode material also includes one or more of Zr, Al, B or Fe elements; optionally, in the lithium-containing nickel cobalt manganese oxide positive electrode material, the mass content of the elements satisfies at least one: the Zr content is 1000-3000ppm, the Al content is 100-1000ppm, and the B element is 20-300ppm.

[0019] In any embodiment of the first aspect, the lithium manganese iron phosphate positive electrode material further contains one or more of Al, B, Ca, Cr, Cu, K, Mg, Na, P, Si, Ti, V or Zn elements.

[0020] In any embodiment of the first aspect, the lithium iron manganese phosphate positive electrode material includes one or more of Al, Ca, Na, Ti or V elements; optionally, in the lithium iron manganese phosphate positive electrode material, the mass content of the elements satisfies at least one: Al content 100-1000ppm, Ca content 50-300ppm, Na content 50-600ppm, Ti content 100-1000ppm, V content 1000-3000ppm.

[0021] In any embodiment of the first aspect, the positive electrode active layer contains one or more of Al, B, Ca, Na, Sr, Ti, V, Y or Zr elements, and based on the total mass of the positive electrode active material, the mass content of each element satisfies: Al: 0.005%-0.1%; Ca: 0.0001%-0.02%; Na: 0.005%-0.06%; Ti: 0.005%-0.15%; V: 0.0001%-0.3%; Zr: 0.005%-0.2%; B: 0.01%-0.1%.

[0022] In any embodiment of the first aspect, the lithium iron manganese phosphate positive electrode material includes a coating layer containing carbon, and the mass content of carbon in the lithium iron manganese phosphate positive electrode material is 1%-3%.

[0023] In any embodiment of the first aspect, in the positive electrode active material, the mass content of Fe element in particles with a particle size less than or equal to Dv10 is M1, and the mass content of Fe element in particles with a particle size greater than or equal to Dv90 is M2, and M1 is greater than M2; and / or the mass content of Ni element in particles with a particle size less than or equal to Dv10 is M3, and the mass content of Ni element in particles with a particle size greater than or equal to Dv90 is M4, and M3 is less than M4.

[0024] In any embodiment of the first aspect, the lithium-containing nickel-cobalt-manganese oxide particles are spherical or quasi-spherical polycrystalline particles, and optionally the volume particle size Dv50 of the lithium-containing nickel-cobalt-manganese oxide polycrystalline particles is 1.5 μm-3 μm.

[0025] In any embodiment of the first aspect, the lithium-containing nickel-cobalt-manganese oxide particles are single-crystal particles; optionally, the volume particle size Dv50 of the lithium-containing nickel-cobalt-manganese oxide single-crystal particles is 7 μm-12 μm.

[0026] In any embodiment of the first aspect, the particles of the lithium manganese iron phosphate positive electrode material are single crystal particles, and optionally the volume particle size Dv50 of the lithium manganese iron phosphate positive electrode material is 0.1 μm-15 μm, and optionally 0.5 μm-2 μm.

[0027] In any embodiment of the first aspect, the positive electrode plate further includes a positive electrode conductive layer, and the positive electrode conductive layer is disposed between the positive electrode current collector and the positive electrode active layer.

[0028] In any embodiment of the first aspect, the positive electrode conductive layer comprises a positive electrode binder and a positive electrode conductive material, and the thickness of the positive electrode conductive layer is 1 μm-2 μm.

[0029] In any embodiment of the first aspect, the thickness of the positive electrode current collector is 9 μm-17 μm, and can be 10 μm-13 μm.

[0030] In any embodiment of the first aspect, the surface density of the negative electrode active layer is 90 mg / 1540.25 mm 2 -170 mg / 1540.25 mm 2 ; Optional: 110mg / 1540.25mm 2 -160mg / 1540.25mm 2 .

[0031] In any embodiment of the first aspect, the compaction density of the negative electrode active layer corresponding to the battery cell at 100% SOC is 1.04 g / cm 3 -1.48g / cm 3 ; Optional: 1.23g / cm 3 -1.38g / cm 3 .

[0032] In any embodiment of the first aspect, the negative electrode plate further includes a negative electrode conductive layer, which is disposed between the negative electrode current collector and the negative electrode active layer, and the negative electrode conductive layer includes 0.5 μm-3 μm, or 1 μm-2 μm.

[0033] In any embodiment of the first aspect, the thickness of the negative electrode current collector is 4 μm-7 μm, and can be 4 μm-5 μm.

[0034] In any embodiment of the first aspect, the negative electrode active layer includes composite graphite particles, the composite graphite particles include: main particles, the main particles include primary particles or secondary particles, the main particles include artificial graphite; and a coating layer, the coating layer is coated on the surface of the main particles, and the coating layer includes amorphous carbon.

[0035] In any embodiment of the first aspect, the mass content of amorphous carbon in the coating layer is 2% to 5% based on the total mass of the composite graphite particles.

[0036] In any embodiment of the first aspect, the negative electrode active layer includes: a first negative electrode active layer, arranged on one side of the negative electrode current collector, the first negative electrode active layer includes one or more of composite graphite particles and natural graphite, optionally, the volume average particle size Dv50 of the negative electrode active material in the first negative electrode active layer is 7.5μm-19.5μm, optionally 12.5μm-18.5μm, and a second negative electrode active layer, arranged on the side of the first negative electrode active layer away from the negative electrode current collector, optionally the second negative electrode active layer includes composite graphite particles, and the volume average particle size Dv50 of the negative electrode active material in the second negative electrode active layer is 7.5μm-19.5μm, optionally 7.5μm-15.5μm.

[0037] In any embodiment of the first aspect, the powder compaction density of the composite graphite particles under a pressure of 20000N is 1.5 g / cm 3 -1.7g / cm 3 , or 1.55g / cm 3 -1.65g / cm 3 .

[0038] In any embodiment of the first aspect, the electrode assembly further comprises an electrolyte, and the lithium ion conductivity of the electrolyte is 10-20 mS / cm or 12-17 mS / cm.

[0039] In any embodiment of the first aspect, the electrolyte includes lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide.

[0040] In any embodiment of the first aspect, the molar ratio of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate is (2-5):10.

[0041] In any embodiment of the first aspect, the battery cell further comprises a shell, the electrode assembly is arranged in the inner cavity of the shell, the length of the shell is L1, the length of the positive electrode sheet is L2, and L2 / L1 is 80%-99%, optionally 88%-99%.

[0042] In any embodiment of the first aspect, the size of the shell has one or more of the following characteristics: the range of L1 is 300mm-950mm; the height of the shell is 85mm-140mm; the thickness of the shell is 10mm-20mm.

[0043] In any embodiment of the first aspect, the shell is an aluminum shell or a steel shell.

[0044] In any embodiment of the first aspect, the battery monomer injection coefficient is 1.9 g / Ah-3.1 g / Ah.

[0045] In any embodiment of the first aspect, the volume energy density of the battery cell is 470Wh / L-570Wh / L.

[0046] A second aspect of the present application provides a battery device, comprising a battery cell provided in any embodiment of the first aspect, wherein the battery device comprises a battery module, a battery pack or an energy storage device.

[0047] A third aspect of the present application provides an electrical device, comprising a battery cell provided in any embodiment of the first aspect or a battery device provided in any embodiment of the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without paying creative work.

[0049] Figure 1 It is a schematic diagram of an electrode assembly according to one embodiment of the present application.

[0050] Figure 2 It is an exploded view of a battery cell according to one embodiment of the present application.

[0051] Figure 3 It is a schematic diagram of a battery pack according to one embodiment of the present application.

[0052] Figure 4 yes Figure 3 An exploded view of a battery pack according to an embodiment of the present application is shown.

[0053] Figure 5 It is a schematic diagram of an electrical device using a battery cell according to an embodiment of the present application as a power source.

[0054] In the drawings, the drawings are not drawn to scale.

[0055] Description of reference numerals:

[0056] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery cell; 51 shell; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0057] The following detailed description and drawings of the embodiments of the present application are used to illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0058] Hereinafter, the battery cells and the electric devices of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0059] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0060] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0061] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0062] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0063] If there is no special explanation, the "include" and "comprising" mentioned in this application represent open-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or comprised.

[0064] If not otherwise specified, in this application, the term "or" is inclusive. For example, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0065] [Battery Cell]

[0066] As analyzed above, the energy density of lithium iron phosphate battery cells is low, in order to increase the energy density of battery cells.

[0067] The present application provides a battery cell, including an electrode assembly, the electrode assembly including a positive electrode sheet, a negative electrode sheet, and a separator located between the positive electrode sheet and the negative electrode sheet, wherein the negative electrode sheet includes a negative electrode current collector and a negative electrode active layer arranged on at least one side of the negative electrode current collector, the negative electrode active layer includes a negative electrode active material, the negative electrode active material includes one or more of a carbon-based material (such as graphite) and a silicon-based material, the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer arranged on at least one side of the positive electrode current collector, the positive electrode active layer includes a positive electrode active material, the positive electrode active material The materials include lithium iron manganese phosphate positive electrode material and lithium-containing nickel cobalt manganese oxide positive electrode material. In the lithium-containing nickel cobalt manganese oxide positive electrode material, the Ni element accounts for 50% to 95% of the total molar amount of the three elements Ni, Co, and Mn, and the lithium-containing nickel cobalt manganese oxide positive electrode material accounts for 5%-95% of the positive electrode active material; in the lithium iron manganese phosphate positive electrode material, the Mn element accounts for 30%-80% of the total molar amount of the Mn element and the Fe element, and the discharge voltage platform of the battery cell at room temperature and a rate of 0.1C is 3.29V-4.15V.

[0068] The energy of a battery cell is related to its voltage platform and capacity, while the capacity is related to the gram capacity of the positive electrode active material. This application aims to study how to design a battery cell with mixed positive electrode materials so that the energy of the battery cell is increased without deteriorating other battery properties such as cycle performance.

[0069] The positive electrode active materials of the battery cell of the present application include lithium iron manganese phosphate positive electrode material and lithium-containing nickel cobalt manganese oxide positive electrode material, wherein the Mn element content of the lithium iron manganese phosphate positive electrode material is positively correlated with the voltage platform of the mixed positive electrode material, but is negatively correlated with the gram capacity of the lithium iron manganese phosphate positive electrode material, and is not conducive to the skeleton stability of the lithium iron manganese phosphate positive electrode material in long-term circulation; while the Ni element content in the lithium-containing nickel cobalt manganese oxide positive electrode material is positively correlated with the voltage platform and gram capacity of the mixed positive electrode material, but is not conducive to the skeleton stability of the lithium-containing nickel cobalt manganese oxide in long-term circulation.

[0070] This application is based on the actual needs of customers for low cost, high specific energy and long cycle, and it is found that by making the Ni element in the lithium-containing nickel cobalt manganese oxide positive electrode material account for 50% to 95% of the total molar amount of the three elements Ni, Co and Mn, and the lithium-containing nickel cobalt manganese oxide positive electrode material accounts for 5%-95% of the positive electrode active material; further by making the Mn element in the lithium iron manganese phosphate positive electrode material account for 30%-80% of the total molar amount of the Mn element and the Fe element, the gram capacity of the mixed positive electrode material is better, and the voltage platform is maintained in an appropriate range, so that the battery cell has both low cost, energy density and high cycle performance.

[0071] At the same time, the lithium iron manganese phosphate positive electrode material has an olivine structure, which is more stable and low-cost than the layered structure of the lithium-containing nickel cobalt manganese oxide positive electrode material. The battery cell using a mixed positive electrode material of lithium iron manganese phosphate positive electrode material and lithium-containing nickel cobalt manganese oxide positive electrode material has improved cycle stability, safety and power performance compared to the battery cell of pure lithium-containing nickel cobalt manganese oxide positive electrode material, and the cost is greatly reduced compared to the lithium-containing nickel cobalt manganese oxide positive electrode material.

[0072] In some embodiments, the discharge voltage platform of the battery cell at room temperature and 0.1C rate is 3.67V-3.86V, such as 3.67V, 3.69V, 3.77V or 3.86V. The positive electrode active material of the battery cell that meets the above discharge voltage platform has a high Ni content in the lithium-containing nickel-cobalt-manganese oxide positive electrode material (further increasing the gram capacity of the material) and / or a high Mn content in the lithium iron manganese phosphate positive electrode material (further increasing the discharge voltage platform of the material), thereby further improving the energy density of the battery cell.

[0073] In some embodiments, in the lithium-containing nickel-cobalt-manganese oxide positive electrode material, the molar content of the Ni element relative to the total molar number of the nickel-cobalt-manganese elements is 80%-95%. The higher the Ni element content, the higher the gram capacity of the lithium-containing nickel-cobalt-manganese oxide positive electrode material, which is more conducive to improving the energy density of the battery cell.

[0074] In some embodiments, in the lithium manganese iron phosphate positive electrode material, the molar content of the Mn element relative to the total molar number of the Mn element and the Fe element is 50%-70%, such as 50%, 60% or 70%. The higher the Mn element content in the lithium manganese iron phosphate positive electrode material, the higher the discharge voltage platform of the lithium manganese iron phosphate, which is more conducive to improving the energy density of the battery cell.

[0075] In some embodiments, based on the total mass of the positive electrode active material, the mass content of the lithium iron manganese phosphate positive electrode material in the positive electrode active material is 50%-95% or 50%-70%. With the positive electrode active material having the above content of lithium iron manganese phosphate positive electrode material, the gram capacity advantages of the two positive electrode materials can be fully utilized, and the stability performance and fast charging performance complement each other, so that the energy density and cycle performance of the battery cell are fully improved.

[0076] The elements in the above materials can be determined by the following methods:

[0077] The positive electrode sheet of the battery cell was fully cleaned with DMC (dimethyl carbonate), and the positive electrode sheet was dried and calcined before collecting the positive electrode material in the positive electrode active layer. The positive electrode material was tested using inductively coupled plasma atomic emission spectrometry (ICP-OES).

[0078] In some embodiments, the energy density of the battery cell can be further increased by the following methods: the surface density of the positive electrode active layer is 200 mg / 1540.25 mm 2 -370mg / 1540.25mm 2 , optional: 240mg / 1540.25mm 2 -340mg / 1540.25mm 2 .

[0079] The above surface density is tested by the following method:

[0080] Take a single-sided coated positive electrode sheet (if it is a double-sided coated sheet, wipe off the positive electrode film on one side first), punch it into a small disc with an area of ​​S1, weigh it, record it as M1, and measure its thickness H1. Then wipe off the positive electrode active material layer of the weighed positive electrode sheet, weigh the weight of the positive electrode collector, record it as M0, and measure its thickness H0. The single-sided coating weight of the positive electrode active material layer (i.e., surface density) = (weight of the positive electrode sheet M1-weight of the positive electrode collector M0) / S1.

[0081] In some embodiments, if a positive electrode conductive layer is disposed between the positive electrode active layer and the positive electrode current collector, the mass of the positive electrode conductive layer is significantly lower than that of the positive electrode active layer, so when testing the compaction density or surface density of the positive electrode active layer, the mass of the positive electrode conductive layer can be ignored. The same is true for the compaction density or surface density test of the negative electrode active layer.

[0082] In some embodiments, the surface capacity of the positive electrode sheet is 50 mAh / 1540.25 mm 2 -350mAh / 1540.25mm 2 , optional 80mAh / 1540.25mm 2 -150mAh / 1540.25mm 2 The energy density of the battery cell having the above-mentioned surface capacity is further improved.

[0083] The above capacity is tested by the following method:

[0084] The positive electrode sheet was assembled into a button battery, charged to 4.2V at a rate of 0.1C, and then discharged to 2.5V at a rate of 0.1C after standing for 30 minutes. The capacity of the button battery is recorded as the positive electrode sheet surface capacity (unit: mAh / 1540.25mm 2 ) = button cell capacity / button cell electrode area*1540.25.

[0085] The compaction density of the positive electrode active layer affects the stability of the electrolyte infiltration and volume expansion in the positive electrode plate, and also affects the volume energy density of the battery cell. Generally, the greater the compaction density, the smaller the pores between the positive electrode active material particles, the worse the wettability of the electrolyte in them, and the smaller the buffer space reserved for the expansion of the positive electrode active material, which affects the charging performance and cycle performance of the battery cell, but can improve the volume energy density of the battery cell; the smaller the compaction density, the larger the pores between the positive electrode active material particles, the better the wettability of the electrolyte in them, and the larger the buffer space reserved for the expansion of the positive electrode active material, so the charging performance and cycle performance of the battery cell are improved, but it will lead to a decrease in the volume energy density of the battery cell. In some embodiments, the compaction density of the corresponding positive electrode active layer in the battery cell at 100% SOC is 2.45g / cm 3 -3.4g / cm 3 , optional 2.5g / cm 3 -3.2g / cm 3 . Thereby achieving the comprehensive performance improvement of energy density, charging performance and cycle performance.

[0086] The 100% SOC state refers to a state in which the battery cell is charged at a rate of 0.33C at room temperature to a voltage of 4.2V and then charged at a constant voltage to a current of less than 0.05C.

[0087] The test method for the compaction density of the positive electrode active layer can be implemented by referring to the following method:

[0088] Based on the above surface density test, the thickness of the positive electrode active layer = the thickness of the positive electrode plate H1-the thickness of the positive electrode collector H0, and the compaction density of the positive electrode active layer = the single-sided coating weight of the positive electrode active layer / the thickness of the single-sided positive electrode active layer.

[0089] In order to more stably improve the compaction density of the positive electrode active layer, in some embodiments, the powder compaction density of the positive electrode active material at 30000N is ≥2.43g / cm 3 , can be selected as ≥2.45g / cm 3 , optional 2.45g / cm 3 -3.0g / cm 3 .

[0090] In some embodiments, the lithium-containing nickel-cobalt-manganese oxide positive electrode material further contains one or more of the elements Zr, Al, B, Fe, Ca, Sr, Ti, V or Y; optionally, the lithium-containing nickel-cobalt-manganese oxide positive electrode material further contains one or more of the elements Zr, Al, B or Fe. The elements in the above-mentioned modified materials may be present in the lithium-containing nickel-cobalt-manganese oxide in the form of doping or coating.

[0091] Elements such as Al, B, Ti, Y, Zr, and Sr in lithium-containing nickel-cobalt-manganese oxides can significantly improve their electrochemical properties, structural stability, and cycle performance. For example:

[0092] Al can form AlO 6 Octahedron, this structure is similar to TMO 6 Octahedral (TM is a transition metal), which does not cause significant lattice distortion. The ionic radius of Al(III) is close to that of TM, so it is easy to dope into the TM layer of lithium-containing nickel-cobalt-manganese oxide. Al doping helps to improve the chemical stability of lithium-containing nickel-cobalt-manganese oxide, reduce cation mixing, and improve its cycle performance.

[0093] The doping of B in lithium-containing NiCoMnO tends to occur on the surface because B has lower energy on the surface than in the bulk phase. The surface enrichment of B helps stabilize the surface structure of lithium-containing NiCoMnO, reduce surface reconstruction, and thus improve the cyclic stability of the material. When co-doped with Al, the competitive doping chemical behavior of B makes it more inclined to aggregate on the surface, achieving synergistic stabilization of the surface and the bulk phase.

[0094] Ti can significantly improve the particle strength of lithium-containing nickel-cobalt-manganese oxide and enhance the cycle performance. After Ti replaces transition metal elements, the strong Ti-O bond formed helps stabilize the lattice structure and prevents adverse changes in the structure during charging and discharging. In addition, Ti doping can also broaden the insertion / extraction channels of Li ions and increase the transmission rate of Li ions.

[0095] Y is beneficial to improve the cycle stability and rate performance of lithium-containing nickel-cobalt-manganese oxide. Y has a large ionic radius and can serve as a supporting framework after doping to inhibit surface structural phase change and Li / Ni mixing. In addition, Y doping can also broaden the transmission channel of Li ions and increase the transmission rate of Li ions.

[0096] Zr can significantly improve the structural stability and thermal stability of lithium-containing nickel-cobalt-manganese oxides. Zr-O bonds are strong, which can stabilize the lattice structure and prevent the precipitation of free oxygen. Zr doping can also expand the unit cell parameters, which is beneficial to the diffusion of Li ions. In addition, Zr doping can also reduce the irreversible capacity loss of lithium-rich NCM.

[0097] Sr is usually co-doped with other elements such as Zr to form SrZrO 3 The larger diameter of Sr can act as a pillar, significantly expanding the lattice unit parameters and O-Li-O interlayer spacing, thereby improving the diffusion kinetics and rate performance of Li ions. Sr / Zr co-doping can also build a strong crystal framework and improve the structural stability and cycle performance of lithium-containing nickel-cobalt-manganese oxides.

[0098] Therefore, elements such as Al, B, Ti, Y, Zr, and Sr can improve the electrochemical performance, structural stability, and cycle performance of lithium-containing nickel-cobalt-manganese oxides to varying degrees. These elements play a role by forming stable chemical bonds, broadening transmission channels, and inhibiting adverse phase changes.

[0099] In order to give full play to the role of each element, in some embodiments, in the lithium-containing nickel cobalt manganese oxide positive electrode material, the mass content of the elements meets one or more of the following characteristics: 1) Zr content 1000-3000ppm; 2) Al content 100-1000ppm; 3) B content 20-300ppm.

[0100] In some embodiments, the lithium iron manganese phosphate positive electrode material also contains one or more of Al, B, Ca, Cr, Cu, K, Mg, Na, P, Si, Ti, V or Zn elements. Optionally, the lithium iron manganese phosphate positive electrode material includes one or more of Al, Ca, Na, Ti or V elements. The elements in the above-mentioned modified materials can be present in the lithium iron manganese phosphate positive electrode material in the form of doping or coating. Among them, the Al element can reduce the resistivity of the material, change the crystal structure, shorten the lithium ion transmission path, and enhance the electrochemical performance. The Ca element can improve the structural stability of the material, improve the cycle life and rate performance of the battery cell, the Na element and the V element can improve the conductivity and cycle stability of the material, and the Ti element can change the crystal structure and improve the charge and discharge performance of the material.

[0101] In order to give full play to the role of each element, in some embodiments of the lithium manganese iron phosphate positive electrode material, the mass content of the elements meets at least one of the following: Al content 100-1000ppm, Ca content 50-300ppm, Na content 50-600ppm, Ti content 100-1000ppm, V content 1000-3000ppm.

[0102] In some embodiments, the positive electrode active layer contains one or more of Al, B, Ca, Na, Sr, Ti, V, Y or Zr elements, and based on the total mass of the positive electrode active material, the mass content of each element satisfies: Al: 0.005%-0.1%; Ca: 0.0001%-0.02%; Na: 0.005%-0.06%; Ti: 0.005%-0.15%; V: 0.0001%-0.3%; Zr: 0.005%-0.2%; B: 0.01%-0.1%.

[0103] In order to improve the conductivity and surface stability of the lithium iron manganese phosphate positive electrode material, in some embodiments, the lithium iron manganese phosphate positive electrode material includes a carbon-containing coating layer, and the mass content of carbon in the lithium iron manganese phosphate positive electrode material is 1%-3%.

[0104] In some embodiments, the gram capacity of the positive electrode active material is increased by size grading of the material particles in the positive electrode active material. In the positive electrode active material, the mass content of Fe element in particles with a particle size less than or equal to Dv10 is M1, and the mass content of Fe element in particles with a particle size greater than or equal to Dv90 is M2, and M1 is greater than M2; and / or the mass content of Ni element in particles with a particle size less than or equal to Dv10 is M3, and the mass content of Ni element in particles with a particle size greater than or equal to Dv90 is M4, and M3 is less than M4.

[0105] Through the above-mentioned particle size control, the small-particle lithium iron manganese phosphate positive electrode material is combined with the large-particle lithium-containing nickel cobalt manganese oxide, and the small particles can be filled in the gaps between the large particles, thereby improving the compaction of the positive electrode active material; and this combination method protects the lithium iron manganese phosphate positive electrode material, effectively reducing the chance of breakage when it is cold pressed at the same pressure.

[0106] The energy density or cycle performance of the battery cell is improved by the particle form of the positive electrode material. In some embodiments, the particles of the lithium-containing nickel-cobalt-manganese oxide are spherical or quasi-spherical polycrystalline particles, and the volume particle size Dv50 of the polycrystalline particles of the lithium-containing nickel-cobalt-manganese oxide is optionally 1.5 μm-3 μm. The polycrystalline form of lithium-containing nickel-cobalt-manganese oxide has a higher gram capacity, so the energy density of the battery cell can be better improved.

[0107] In some embodiments, the particles of lithium-containing nickel-cobalt-manganese oxide are single-crystal particles, and optionally the volume particle size Dv50 of the single-crystal particles of lithium-containing nickel-cobalt-manganese oxide is 7 μm-12 μm. The structure of lithium-containing nickel-cobalt-manganese oxide in single-crystal form is more stable, so the cycle performance of the battery cell can be better improved.

[0108] In some embodiments, in order to further increase the gram capacity of the lithium iron manganese phosphate positive electrode material, the particles of the lithium iron manganese phosphate positive electrode material are single crystal particles, and optionally the volume particle size Dv50 of the lithium iron manganese phosphate positive electrode material is 0.1μm-15μm, optionally 0.5μm-2μm.

[0109] In order to improve the rate performance of the battery cell, in some embodiments, the positive electrode plate further includes a positive electrode conductive layer, which is disposed between the positive electrode current collector and the positive electrode active layer. The positive electrode conductive layer is used to increase the electron transfer rate, thereby improving the rate performance of the battery cell.

[0110] In order to improve the bonding between the positive electrode current collector and the positive electrode active layer by using the positive electrode conductive layer, in some embodiments, the positive electrode conductive layer includes a positive electrode binder and a positive electrode conductive material.

[0111] In some embodiments, the thickness of the positive electrode conductive layer is 1 μm-2 μm, so that the positive electrode conductive layer can be fully utilized to improve the conductivity, and the excessive thickness of the positive electrode conductive layer can be avoided to affect the energy density of the battery cell.

[0112] In some embodiments, the number of the above-mentioned positive electrode active layers is a single layer or multiple layers. If it is a single layer, the above-mentioned two positive electrode active materials are mixed in the same layer; if it is a multi-layer, the two materials can be arranged in different layers respectively or mixed in different mixing ratios and arranged in different layers.

[0113] The strength of the positive electrode current collector is related to its thickness. Generally, the greater the thickness, the greater the strength, but the greater the strength, the worse the ductility, and it will also cause the energy density of the battery cell to decrease. During the charge and discharge cycle, the positive electrode active material expands, so the positive electrode current collector needs to have a certain strength to restrain the expansion and also needs to have a certain ductility to adapt to the increase in the area of ​​the active layer due to the expansion. In some embodiments, the thickness of the positive electrode current collector is 9μm-17μm, and can be optionally 10μm-13μm. The positive electrode current collector within this thickness range has little effect on the energy density, and it has a good matching ability of strength and ductility, thereby effectively reducing the risk of cracking of the current collector caused by the expansion of the battery cell during the charging process.

[0114] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0115] In some embodiments, the positive electrode film layer may also optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0116] In some embodiments, the positive electrode film layer may further include a conductive agent, for example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0117] In some embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0118] [Negative electrode]

[0119] In some embodiments, in order to fully utilize the capacity of the positive electrode active material, the surface density of the negative electrode active layer is 90 mg / 1540.25 mm 2 -170 mg / 1540.25 mm2 ; Optional: 110mg / 1540.25mm 2 -160 mg / 1540.25 mm 2 .

[0120] When the battery cell is charged, the negative electrode active material expands, resulting in a decrease in the compaction density of the negative electrode active layer. In some embodiments, the compaction density of the negative electrode active layer corresponding to the battery cell at 100% SOC is 1.04 g / cm 3 -1.48g / cm 3 ; Optional: 1.23g / cm 3 -1.38g / cm 3 The negative electrode sheet with the above compaction density has small expansion deformation and good electrolyte infiltration, thereby improving the cycle performance of the battery cell.

[0121] In some embodiments, the negative electrode plate further includes a negative electrode conductive layer, which is disposed between the negative electrode current collector and the negative electrode active layer, and the negative electrode conductive layer includes 0.5 μm-3 μm, or 1 μm-2 μm. The negative electrode conductive layer is used to improve the conductivity of the negative electrode plate, thereby improving the rate performance of the battery cell.

[0122] The same considerations as above for selecting the thickness of the positive electrode current collector, in some embodiments, the thickness of the negative electrode current collector is 4μm-7μm, and can be 4μm-5μm. The negative electrode current collector within this thickness range has little effect on the energy density, and has good strength and ductility matching capabilities, thereby effectively reducing the risk of current collector cracking caused by expansion during the charging process of the battery cell.

[0123] In some embodiments, the negative electrode active layer includes composite graphite particles, the composite graphite particles include body particles and coating layers, the body particles include primary particles or secondary particles, the body particles include artificial graphite, the coating layer is coated on the surface of the body particles, and the coating layer includes amorphous carbon. Artificial graphite coated with amorphous carbon has a simple structure and high conductivity.

[0124] On the basis of improving the conductivity of the composite graphite particles, the gram capacity of the composite graphite particles is improved as much as possible. In some embodiments, the mass content of amorphous carbon in the coating layer can be selected to be 2% to 5% based on the total mass of the composite graphite particles.

[0125] In some embodiments, the negative electrode active layer has one or more layers. When the negative electrode active layer has multiple layers, negative electrode active materials with corresponding characteristics can be arranged in different layers of the negative electrode active layers according to different purposes.

[0126] In some embodiments, the negative electrode active layer includes a first negative electrode active layer and a second negative electrode active layer, the first negative electrode active layer is disposed on one side of the negative electrode current collector, the first negative electrode active layer includes one or more of composite graphite particles and natural graphite, the second negative electrode active layer is disposed on a side of the first negative electrode active layer away from the negative electrode current collector, and the second negative electrode active layer includes composite graphite particles. The first negative electrode active layer is used to increase the energy density of the battery cell, and the second negative electrode active layer is used to improve the charging rate of the battery cell.

[0127] In some embodiments, the volume average particle size Dv50 of the negative electrode active material in the first negative electrode active layer is 7.5 μm-19.5 μm, and can be 12.5 μm-18.5 μm. In some embodiments, the volume average particle size Dv50 of the negative electrode active material in the second negative electrode active layer is 7.5 μm-19.5 μm, and can be 7.5 μm-15.5 μm. The first negative electrode active layer and the second negative electrode active layer each use a negative electrode active material with a corresponding particle size. When the particle size of the negative electrode active material in the second negative electrode active layer is smaller than that of the negative electrode active material in the first negative electrode active layer, the wettability of the negative electrode active layer is better, and the short migration path of lithium ions can improve the kinetic performance of the battery cell.

[0128] In order to maximize the contribution of the second negative electrode active layer to the energy density of the battery cell, in some embodiments, the powder compaction density of the composite graphite particles under a pressure of 20000N is 1.5g / cm 3 -1.85g / cm 3 , or 1.55g / cm 3 -1.75g / cm 3 .

[0129] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, a copper foil may 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 may be formed by forming a metal material (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.).

[0130] In some embodiments, the negative electrode film layer may further include a binder. As an example, the binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

[0131] In some embodiments, the negative electrode film layer may further include a conductive agent. As an example, the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0132] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0133] 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 collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0134] [Isolation film]

[0135] The present application has no particular limitation on the type of isolation membrane, and any known porous isolation membrane with good chemical stability and mechanical stability can be selected.

[0136] In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0137] In some embodiments, the isolation membrane includes a porous base membrane and a functional layer disposed on at least one side of the porous base membrane. That is, the isolation membrane is a composite film. The corresponding functional layer is selected according to different functional requirements, and this application will not repeat it here.

[0138] [Electrolytes]

[0139] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0140] In some embodiments, the battery cell further includes an electrolyte solution including an electrolyte salt and a solvent.

[0141] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0142] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0143] In some embodiments, the electrolyte may further include additives. As examples, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0144] In some embodiments, the lithium ion conductivity of the electrolyte is selected to be 10-20 mS / cm or 12-17 mS / cm.

[0145] In some embodiments, the electrolyte includes lithium hexafluorophosphate (LiPF 6 ) and lithium bis(fluorosulfonyl)imide (LiFSI). LiFSI can improve the lithium ion transfer rate, thereby improving the charging rate of the battery cell; and it has high temperature stability, thus improving the high temperature cycle performance of the battery cell.

[0146] In some embodiments, the molar ratio of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate is (2-5): 10. Thus, the above lithium salt is used to improve the cycle stability and charging rate of the battery cell, while controlling the excessive increase in the cost of the battery cell.

[0147] In some embodiments, the battery cell further includes a shell, the electrode assembly is disposed in the inner cavity of the shell, the length of the shell is L1, the length of the positive electrode sheet is L2, and L2 / L1 is 80%-99%, optionally 88%-99%, thereby further improving the volume energy density of the battery cell.

[0148] In some embodiments, the size of the shell has one or more of the following characteristics: L1 ranges from 300 mm to 950 mm; the height of the shell is from 85 mm to 140 mm; the thickness of the shell is from 10 mm to 20 mm.

[0149] In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery cell may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0150] In some embodiments, the housing is an aluminum housing or a steel housing.

[0151] In some embodiments, the battery cell injection coefficient is 1.9 g / Ah-3.1 g / Ah. The injection coefficient within the above range makes the lithium ion transmission during the cycle of the battery cell smoother and more stable.

[0152] In some embodiments, the volume energy density of the battery cell is 470Wh / L-570Wh / L.

[0153] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0154] The present application has no particular limitation on the shape of the battery cell, which may be cylindrical, square or any other shape. Figure 1 The electrode assembly 52 is a square structure as an example.

[0155] In some embodiments, reference Figure 2 , the outer packaging may include a shell 51 and a top cover assembly 53. Among them, the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the top cover assembly 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0156] In some embodiments, battery cells may be assembled into a battery module. The number of battery cells contained in the battery module may be one or more. The specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

[0157] In the battery module 4, the plurality of battery cells 5 may be arranged in sequence along the thickness direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.

[0158] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0159] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

[0160] Figure 3 and Figure 4 1 is a battery pack 1 as an example. Figure 3 and Figure 4 The battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0161] In addition, the present application also provides an electric device, which includes a battery cell provided in the present application. The battery cell can be used as a power source for the electric device, or as an energy storage unit for the electric device. The electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.

[0162] As the electrical device, a battery cell, a battery module or a battery pack can be selected according to its usage requirements.

[0163] Figure 5 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the power consumption device's requirements for high power and high energy density of battery cells, a battery pack or a battery module can be used.

[0164] [Example]

[0165] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0166] Example 1

[0167] Positive electrode

[0168] The positive electrode active material layer includes positive electrode active material, binder polyvinylidene fluoride, and conductive agent acetylene black (mass ratio is 97:2:1). The positive electrode active material includes lithium iron manganese phosphate positive electrode material and lithium-containing nickel cobalt manganese oxide positive electrode material. In the positive electrode active material, the mass ratio of lithium-containing nickel cobalt manganese oxide positive electrode material and lithium iron manganese phosphate positive electrode material is 5:95, and the mass content of carbon in the lithium iron manganese phosphate positive electrode material is about 2%. In the lithium-containing nickel cobalt manganese oxide positive electrode material, the subscripts of Ni, Co and Mn in the chemical formula are rounded data. Because the content of other metal elements and oxygen elements M other than lithium is trace compared to the content of Ni, Co and Mn, these elements and their atomic numbers are not reflected in the chemical formula, but it does not mean that element M has no effect on battery performance. In the positive electrode active material, the mass content of Al element is 0.063%, the mass content of B is 0.0039%, and the mass content of Zr is 0.256%. The surface density of the positive electrode active layer is set to 300 mg / 1540.25 mm 2 The thickness of the current collector aluminum foil is 12μm, the positive electrode film layer is located on both sides of the aluminum foil, and there is a conductive primer layer between the positive electrode film layer and the aluminum foil. The conductive primer layer is a film layer formed by mixing the positive electrode conductive agent superconducting carbon, the positive electrode binder polyacrylate and the solvent evenly and then coating it on the surface of the positive electrode current collector and drying it. The thickness is 1μm, the mass content of the positive electrode conductive agent in the positive electrode conductive layer is 50%, and the mass content of the positive electrode binder in the negative electrode conductive layer is 50%. The length of the positive electrode sheet is 542mm and the height is 94mm.

[0169] Negative electrode

[0170] The negative electrode active material layer includes an upper layer (away from the current collector) and a lower layer (close to the current collector). The lower layer includes a 96:1:2:1 negative electrode active material, a conductive agent acetylene black, a binder styrene butadiene rubber and a thickener sodium carboxymethyl cellulose. The negative electrode active material is composed of composite graphite particles (the composite graphite particles include artificial graphite and a carbon coating layer, the carbon coating layer is coated on the surface of the artificial graphite, and the mass content of the carbon coating layer is 3.5%) and natural graphite in a mass ratio of 5:5, wherein the Dv50 of the composite graphite particles is 17μm, and the powder compaction density under a pressure of 20000N is 1.6g / cm 3 ; The Dv50 of natural graphite is 18μm. The negative electrode active material in the upper layer is composite graphite particles, with a Dv50 of 10μm and a powder compaction density of 1.8g / cm under a pressure of 20000N. 3 .

[0171] The negative electrode current collector is a copper foil of 5 μm, there is a negative electrode conductive layer between the copper foil and the lower film layer, the conductive primer is a film layer formed by mixing the negative electrode conductive agent superconducting carbon, the negative electrode binder styrene-butadiene rubber SBR, the thickener sodium carboxymethyl cellulose (CMC-Na) and the solvent water evenly, and then coating it on the surface of the negative electrode current collector and drying it. The thickness is 1 μm, the mass content of the negative electrode conductive agent in the negative electrode conductive layer is 35%, the mass content of the negative electrode binder in the negative electrode conductive layer is 60%, and the mass content of the thickener in the negative electrode conductive layer is 5%.

[0172] Electrolyte

[0173] The organic solvents include ethyl acetate EA, ethylene carbonate EC, ethyl methyl carbonate EMC (mass ratio 50:35:15), 10.5% lithium hexafluorophosphate (LiPF 6 ) and 4.5% lithium bis(fluorosulfonyl)imide LiFSI as lithium salt, 2.5% additive vinylene carbonate VC, 1% fluoroethylene carbonate FEC, 0.5% 1,3 propene sultone PS, 0.5% vinyl sulfite DTD and 0.5% lithium difluorophosphate LiPO 2 F 2 The conductivity of the electrolyte is 13mS / cm.

[0174] Isolation film

[0175] A polyethylene (PE) film coated with nano-aluminum oxide was used as the isolation film.

[0176] Battery Cell

[0177] The electrode assembly is obtained by stacking the positive electrode sheet, the separator and the negative electrode sheet. The electrode assembly is added to the outer packaging square aluminum shell (length 550mm, thickness 19.5mm, height 100mm), and the electrolyte is injected after drying, and the injection coefficient is 2.9. After packaging, high temperature standing, formation, secondary injection, aging, capacity and other processes, a battery cell is obtained.

[0178] Pole piece test

[0179] Compaction density of positive electrode active layer / negative electrode active layer:

[0180] It refers to the compaction density of the positive electrode active layer / negative electrode active layer after charging the battery cell to a voltage of 4.2V at a rate of 0.33C at 25°C and then charging at a constant voltage to a current less than 0.05C. The compaction density of the negative electrode active layer is 1.36g / cm 3 .

[0181] Test methods for surface density and compacted density:

[0182] Take a single-sided coated positive electrode sheet (if it is a double-sided coated sheet, wipe off the positive electrode active layer on one side first), punch it into small discs with an area of ​​S1, weigh it, record it as M1, and measure its thickness H1. Then wipe off the positive electrode active layer of the weighed positive electrode sheet, weigh the weight of the positive electrode collector, record it as M0, and measure its thickness H0. The single-sided coating weight of the positive electrode active layer (also known as the surface density) = (the weight of the positive electrode sheet M1-the weight of the positive electrode collector M0) / S1, the thickness of the positive electrode active layer = the thickness of the single-sided positive electrode sheet H1-the thickness of the positive electrode collector H0, and the compacted density of the positive electrode active layer = the single-sided coating weight of the positive electrode active layer / the thickness of the single-sided positive electrode active layer.

[0183] The test methods for the surface density and compaction density of the negative electrode are the same as above.

[0184] Volume energy density test method:

[0185] Place the battery cell at room temperature, charge it to 4.2V at a constant current of 0.33C, and then charge it to 0.05C at a constant voltage; discharge it to 2.5V at a constant current of 0.33C, and record the discharge capacity A0 at this time, in Ah; use a caliper to measure the length, width, and height of the battery cell (generally calculated based on the battery shell size, excluding the electrode terminal height and the insulating film outside the shell), and calculate the volume of the single battery V0, in L; the volume energy density of the battery cell VED = (A0×discharge platform voltage) / V0, in Wh / L.

[0186] Cycle life test method:

[0187] The number of cycles of the battery cell to 80% SOH:

[0188] At 45°C, charge the battery cell at 1C constant current to a charge cutoff voltage of 4.2V, and then discharge it at 1C constant current to 2.0V. This is a charge and discharge cycle. Repeat the above charge and discharge cycle steps until the cycle capacity retention rate (i.e. Cn / C0×100%) is 80% (the discharge capacity at 1C constant current to 2.0V is recorded as C0, and Cn is the discharge capacity of the nth cycle). Record the number of cycles. The more cycles, the better the cycle performance of the battery cell.

[0189] In Examples 2 to 6 and Comparative Examples 1 to 3, the composition of the positive electrode material is adjusted on the basis of Example 1, and the specific composition is shown in Table 1. In addition, the surface density of the positive electrode active layer of Examples 2 to 6 and Comparative Examples 1 to 3 is the same as that of Example 1. In Table 1, A:B represents the mass ratio of the lithium-containing nickel cobalt manganese oxide positive electrode material to the lithium iron manganese phosphate positive electrode material.

[0190]

[0191] In Table 1, the chemical formula is LiNi0.8 Co 0.1 Mn 0.1 O 2 The contents of other elements in the lithium-containing nickel-cobalt-manganese oxide positive electrode material are as follows: the mass content of Al is 0.062%, the mass content of B is 0.0037%, the mass content of Ti is 0.0003%, the mass content of Y is 0.008%, the mass content of Zr is 0.25%, and the mass content of Sr is 0.0001%; ​​the chemical formula is LiNi 0.95 Co 0.03 Mn 0.02 O 2 The contents of other elements in the nickel-containing lithium transition metal oxide are as follows: the mass content of Al is 0.058%, the mass content of B is 0.0034%, the mass content of Ti is 0.0003%, the mass content of Y is 0.007%, the mass content of Zr is 0.23%, and the mass content of Sr is 0.0001%; ​​the chemical formula is LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 The contents of other elements in the lithium-containing nickel-cobalt-manganese oxide positive electrode material are as follows: the mass content of Al is 0.064%, the mass content of B is 0.041%, the mass content of Ti is 0.0004%, the mass content of Y is 0.008%, the mass content of Zr is 0.26%, and the mass content of Sr is 0.0001%.

[0192] According to the comparison between the examples and the comparative examples in Table 1, it can be seen that controlling the content of nickel in the lithium-containing nickel-cobalt-manganese oxide positive electrode material, the lithium content of manganese in the lithium iron manganese phosphate positive electrode material, and the voltage platform of the battery cell within the range set in the present application can not only achieve a high energy density of the battery cell, but also help maintain a high cycle stability of the battery cell.

[0193] The following examines the effect of the mass ratio of the lithium-containing nickel cobalt manganese oxide positive electrode material and the lithium iron manganese phosphate positive electrode material on the energy density and cycle performance of the battery cell. Examples 7 to 9 are based on Example 5, except that only the mass ratio of the lithium-containing nickel cobalt manganese oxide positive electrode material and the lithium iron manganese phosphate positive electrode material (i.e., A:B in Table 2) is adjusted, and the rest remains unchanged. The specific test data is recorded in Table 2.

[0194] Table 2

[0195] According to the data in Table 2, it can be seen that as the content of lithium manganese iron phosphate positive electrode material decreases, the voltage platform of the battery cell is slightly improved, the number of cycles is slightly reduced, but the energy density of the battery cell is significantly improved.

[0196] The following investigates the effect of the surface capacity of the positive electrode active layer on the energy density and cycle performance of the battery cell. Based on Example 5, the surface density of the positive electrode active layer is adjusted while other parameters remain unchanged, thereby adjusting the surface capacity of the positive electrode active layer. The test results are recorded in Table 3.

[0197] Table 3

[0198] According to the data in Table 3, it can be seen that when increasing the surface capacity of the positive electrode active layer, appropriately adjusting the surface density of the negative electrode active layer is beneficial to fully utilizing the surface capacity of the positive electrode active layer, thereby improving the energy density of the battery cell; in the trend of increasing the surface capacity of the positive electrode active layer, the cycle performance of the battery cell decreases slightly, but the overall level is high, indicating that the surface capacity has little effect on the cycle performance.

[0199] The following investigates the effect of the compaction of the positive electrode active layer on the energy density and cycle performance of the battery cell. Based on Example 5, only the compaction of the positive electrode active layer is adjusted to change the compaction at full charge, and the other settings remain unchanged. The test results are recorded in Table 4.

[0200] Table 4

[0201] According to the data comparison in Table 4, it can be seen that as the full charge density of the positive electrode active layer increases, the volume energy density of the battery cell increases, but it will cause a slight decrease in the cycle performance of the battery cell.

[0202] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, comprising an electrode assembly, wherein the electrode assembly comprises a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet, wherein: The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one side of the negative electrode current collector, wherein the negative electrode active layer includes a negative electrode active material, and the negative electrode active material includes one or more of a carbon-based material and a silicon-based material. The positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer disposed on at least one side of the positive electrode current collector, wherein the positive electrode active layer comprises a positive electrode active material, and the positive electrode active material comprises a lithium manganese iron phosphate positive electrode material and a lithium-containing nickel cobalt manganese oxide positive electrode material. In the lithium-containing nickel-cobalt-manganese oxide positive electrode material, the Ni element accounts for 50% to 95% of the total molar amount of the three elements Ni, Co, and Mn, and the lithium-containing nickel-cobalt-manganese oxide positive electrode material accounts for 5%-95% of the positive electrode active material; in the lithium iron manganese phosphate positive electrode material, the Mn element accounts for 30%-80% of the total molar amount of the Mn element and the Fe element; Moreover, the discharge voltage platform of the battery cell at room temperature and a discharge rate of 0.1C is 3.29V-4.15V.

2. The battery cell according to claim 1, wherein: The discharge voltage platform of the battery cell at room temperature and 0.1C rate is 3.67V-3.86V.

3. The battery cell according to claim 1 or 2, wherein: In the lithium-containing nickel-cobalt-manganese oxide positive electrode material, the molar content of the Ni element relative to the total molar number of the nickel-cobalt-manganese elements is 80%-95%.

4. The battery cell according to any one of claims 1 to 3, wherein: In the lithium manganese iron phosphate positive electrode material, the molar content of the Mn element relative to the total molar number of the Mn element and the Fe element is 50%-70%.

5. The battery cell according to any one of claims 1 to 4, wherein: Based on the total mass of the positive electrode active material, the mass content of the lithium manganese iron phosphate positive electrode material is 50%-95%.

6. The battery cell according to any one of claims 1 to 5, wherein: Based on the total mass of the positive electrode active material, the mass content of the lithium manganese iron phosphate positive electrode material is 50%-70%.

7. The battery cell according to any one of claims 1 to 6, wherein: The surface density of the positive electrode active layer is 200 mg / 1540.25 mm 2 -370mg / 1540.25mm 2 , optional: 240mg / 1540.25mm 2 -340mg / 1540.25mm 2 .

8. The battery cell according to any one of claims 1 to 7, wherein: The surface capacity of the positive electrode plate is 50mAh / 1540.25mm 2 -350mAh / 1540.25mm 2 , optional 80mAh / 1540.25mm 2 -150mAh / 1540.25mm 2 .

9. The battery cell according to any one of claims 1 to 8, wherein: The compaction density of the positive electrode active layer corresponding to the battery cell at 100% SOC is 2.45 g / cm 3 -3.4g / cm 3 , optional 2.5g / cm 3 -3.2g / cm 3 .

10. The battery cell according to any one of claims 1 to 9, wherein: The powder compaction density of the positive electrode active material at 30000N is ≥2.43g / cm 3 , can be selected as ≥2.45g / cm 3 , optional 2.45g / cm 3 -3.0g / cm 3 .

11. The battery cell according to any one of claims 1 to 10, wherein: The lithium-containing nickel-cobalt-manganese oxide positive electrode material also contains one or more of the elements Zr, Al, B, Fe, Ca, Sr, Ti, V or Y.

12. The battery cell according to claim 11, wherein: The lithium-containing nickel-cobalt-manganese oxide positive electrode material also includes one or more of Zr, Al, B or Fe elements; optionally, in the lithium-containing nickel-cobalt-manganese oxide positive electrode material, the mass content of the elements satisfies at least one of the following: Zr content 1000-3000ppm, Al content 100-1000ppm, B content 20-300ppm.

13. The battery cell according to any one of claims 1 to 12, wherein: The lithium iron manganese phosphate positive electrode material also contains one or more of the elements Al, B, Ca, Cr, Cu, K, Mg, Na, P, Si, Ti, V or Zn.

14. The battery cell according to claim 13, wherein: The lithium iron manganese phosphate positive electrode material includes one or more of Al, Ca, Na, Ti or V elements; optionally, in the lithium iron manganese phosphate positive electrode material, the mass content of the elements satisfies at least one of the following: Al content 100-1000ppm, Ca content 50-300ppm, Na content 50-600ppm, Ti content 100-1000ppm, V content 1000-3000ppm.

15. The battery cell according to any one of claims 1 to 15, wherein: The positive electrode active layer contains one or more of Al, B, Ca, Na, Sr, Ti, V, Y or Zr elements, and based on the total mass of the positive electrode active material, the mass content of each element satisfies: Al: 0.005%-0.1%; Ca: 0.0001%-0.02%; Na: 0.005%-0.06%; Ti: 0.005%-0.15%; V: 0.0001%-0.3%; Zr: 0.005%-0.2%; B: 0.01%-0.1%.

16. The battery cell according to any one of claims 1 to 15, wherein: The lithium iron manganese phosphate positive electrode material comprises a carbon-containing coating layer, and the mass content of carbon in the lithium iron manganese phosphate positive electrode material is 1%-3%.

17. The battery cell according to any one of claims 1 to 16, wherein: In the positive electrode active material, The mass content of Fe in particles with a particle size less than or equal to Dv10 is M1, and the mass content of Fe in particles with a particle size greater than or equal to Dv90 is M2, where M1 is greater than M2; and / or The mass content of Ni element in particles with a particle size less than or equal to Dv10 is M3, and the mass content of Ni element in particles with a particle size greater than or equal to Dv90 is M4, and M3 is less than M4.

18. The battery cell according to any one of claims 1 to 17, wherein: The lithium-containing nickel-cobalt-manganese oxide particles are spherical or quasi-spherical polycrystalline particles. Optionally, the volume particle size Dv50 of the lithium-containing nickel-cobalt-manganese oxide polycrystalline particles is 1.5 μm-3 μm.

19. The battery cell according to any one of claims 1 to 17, wherein: The lithium-containing nickel-cobalt-manganese oxide particles are single-crystal particles; optionally, the volume particle size Dv50 of the lithium-containing nickel-cobalt-manganese oxide single-crystal particles is 7 μm-12 μm.

20. The battery cell according to any one of claims 1 to 19, wherein: The particles of the lithium iron manganese phosphate positive electrode material are single crystal particles. Optionally, the volume particle size Dv50 of the lithium iron manganese phosphate positive electrode material is 0.1 μm-15 μm, and can be optionally 0.5 μm-2 μm.

21. The battery cell according to any one of claims 1 to 20, wherein: The positive electrode plate further includes a positive electrode conductive layer, and the positive electrode conductive layer is arranged between the positive electrode current collector and the positive electrode active layer.

22. The battery cell according to claim 21, wherein: The positive electrode conductive layer comprises a positive electrode binder and a positive electrode conductive material, and the thickness of the positive electrode conductive layer is 1 μm-2 μm.

23. The battery cell according to any one of claims 1 to 22, wherein: The thickness of the positive electrode current collector is 9 μm-17 μm, and can be 10 μm-13 μm.

24. The battery cell according to any one of claims 1 to 23, wherein: The surface density of the negative electrode active layer is 90 mg / 1540.25 mm 2 -170 mg / 1540.25 mm 2 ; Optional: 110mg / 1540.25mm 2 -160 mg / 1540.25 mm 2 .

25. The battery cell according to any one of claims 1 to 24, wherein: The compaction density of the negative electrode active layer corresponding to the battery cell at 100% SOC is 1.04 g / cm 3 -1.48g / cm 3 ; Optional: 1.23g / cm 3 -1.38g / cm 3 .

26. The battery cell according to any one of claims 1 to 25, wherein: The negative electrode plate further includes a negative electrode conductive layer, which is disposed between the negative electrode current collector and the negative electrode active layer. The negative electrode conductive layer includes 0.5 μm-3 μm, or 1 μm-2 μm.

27. The battery cell according to any one of claims 1 to 26, wherein: The thickness of the negative electrode current collector is 4 μm-7 μm, and can be 4 μm-5 μm.

28. The battery cell according to any one of claims 1 to 27, wherein: The negative electrode active layer includes composite graphite particles, and the composite graphite particles include: A bulk particle, wherein the bulk particle comprises a primary particle or a secondary particle, and the bulk particle comprises artificial graphite; and The coating layer is coated on the surface of the main particle, and the coating layer includes amorphous carbon.

29. The battery cell according to claim 28, wherein: The mass content of amorphous carbon in the coating layer is 2% to 5% based on the total mass of the composite graphite particles.

30. The battery cell according to claim 28 or 29, wherein: The negative electrode active layer comprises: A first negative electrode active layer is disposed on one side of the negative electrode current collector, the first negative electrode active layer comprises one or more of composite graphite particles and natural graphite, and optionally the volume average particle size Dv50 of the negative electrode active material in the first negative electrode active layer is 7.5 μm-19.5 μm, and optionally 12.5 μm-18.5 μm, and The second negative electrode active layer is arranged on the side of the first negative electrode active layer away from the negative electrode current collector. Optionally, the second negative electrode active layer includes composite graphite particles. The volume average particle size Dv50 of the negative electrode active material in the second negative electrode active layer is 7.5μm-19.5μm, and can be optionally 7.5μm-15.5μm.

31. The battery cell according to any one of claims 28 to 30, wherein: The powder compaction density of the composite graphite particles under a pressure of 20000N is 1.5g / cm 3 -1.7g / cm 3 , or 1.55g / cm 3 -1.65g / cm 3 .

32. The battery cell according to any one of claims 1 to 31, wherein: The electrode assembly further includes an electrolyte, and the lithium ion conductivity of the electrolyte is 10-20 mS / cm or 12-17 mS / cm.

33. The battery cell according to claim 32, wherein: The electrolyte includes lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide.

34. The battery cell according to claim 33, wherein: The molar ratio of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is (2-5):

10.

35. The battery cell according to any one of claims 1 to 34, wherein the battery cell further comprises a shell, the electrode assembly is arranged in an inner cavity of the shell, the length of the shell is L1, the length of the positive electrode sheet is L2, and L2 / L1 is 80%-99%, and can be optionally 88%-99%.

36. The battery cell according to claim 35, wherein: The dimensions of the housing have one or more of the following characteristics: The range of L1 is 300mm-950mm; The height of the housing is 85 mm to 140 mm; The thickness of the shell is 10mm-20mm.

37. The battery cell according to claim 35 or 36, wherein: The shell is an aluminum shell or a steel shell.

38. The battery cell according to any one of claims 1 to 37, wherein: The battery monomer injection coefficient is 1.9g / Ah-3.1g / Ah.

39. The battery cell according to claims 1 to 38, wherein: The volume energy density of the battery cell is 470Wh / L-570Wh / L.

40. A battery device comprising the battery cell according to any one of claims 1 to 39, wherein the battery device comprises a battery module, a battery pack or an energy storage device.

41. An electrical device comprising the battery cell according to any one of claims 1 to 39 or the battery device according to claim 40.

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