Battery monomer, battery device and power utilization device

Abstract

The invention provides a battery monomer, a battery device and a power utilization device. The battery monomer comprises a positive pole piece and a negative pole piece, the negative pole piece comprises a negative pole current collector and a negative pole active layer arranged on at least one side of the negative pole current collector, the negative pole active layer comprises a negative pole material, and the negative pole material comprises graphite; 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 material, the positive pole material comprises a positive pole active material, and the positive pole active material comprises a lithium manganese iron phosphate material and a lithium iron phosphate material; the mass ratio of the lithium manganese iron phosphate material in the positive electrode active material is 50%-95%; and the powder resistivity of the positive electrode material at 12MPa is 5-70 omega.cm. The energy density and the power performance of the battery monomer are improved at the same time.

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] In recent years, as the application scope of batteries has become more and more extensive, batteries are widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields. As batteries have made great progress, higher requirements have been put forward for their energy density and power performance. Summary of the invention

[0003] The present application is made in view of the above problems, and its purpose is to provide a battery cell, a battery device and an electric device. The energy density and power performance of the battery cell of the present application are improved at the same time.

[0004] In order to achieve the above-mentioned object, the first aspect of the present application provides a battery cell, comprising a positive electrode sheet and a negative electrode sheet; wherein:

[0005] The negative electrode sheet comprises 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 comprises a negative electrode material, and the negative electrode material comprises graphite;

[0006] 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 material, and the positive electrode material comprises a positive electrode active material;

[0007] The positive electrode active material comprises lithium iron manganese phosphate material and lithium iron phosphate material, wherein the mass proportion of the lithium iron manganese phosphate material in the positive electrode active material is 50%-95%; the powder resistivity of the positive electrode material at 12 MPa is 5-70Ω·cm.

[0008] The platform voltage of lithium iron manganese phosphate material is higher than that of lithium iron phosphate material. Increasing the content of lithium iron manganese phosphate material in the mixed system is beneficial to improving the energy density of the battery cell. However, since the powder resistivity of lithium iron manganese phosphate material is greater than that of lithium iron phosphate material, it is easy to cause the powder resistivity of the mixture of the two to be too large, which deteriorates the power performance of the battery cell. This application controls the ratio of lithium iron manganese phosphate material and lithium iron phosphate material to make the battery cell have a higher energy density, and further improves the power performance of the battery cell while improving the energy density by adjusting the powder resistivity range of the positive electrode material.

[0009] In any embodiment, the mass proportion of the lithium manganese iron phosphate material in the positive electrode active material is 50%-70%.

[0010] This is conducive to improving the energy density and power performance of the battery cell at the same time. In addition, when the mass proportion of lithium iron manganese phosphate material in the positive electrode active material increases within the above range, the energy density of the battery cell is further improved; when the mass proportion of lithium iron manganese phosphate material in the positive electrode active material decreases within the above range, the power performance of the battery cell is further improved.

[0011] In any embodiment, the powder resistivity of the lithium manganese iron phosphate material at 12 MPa is 8-120 Ω·cm, and can be optionally 8-80 Ω·cm.

[0012] In any embodiment, the volume average particle size Dv50 of the lithium manganese iron phosphate material is 0.1-1.2 μm, and can be optionally 0.2-0.8 μm.

[0013] Therefore, the powder resistivity and volume average particle size Dv50 of the lithium manganese iron phosphate material within the above range is beneficial to improving the energy density of the battery cell while enhancing the power performance of the battery cell.

[0014] In any embodiment, in the lithium manganese iron phosphate material, the molar ratio of manganese atoms to iron atoms is 2:8-8:2.

[0015] In any embodiment, the powder resistivity of the lithium iron phosphate material at 12 MPa is 3-100 Ω·cm, and can be optionally 3-20 Ω·cm.

[0016] In any embodiment, the volume average particle size Dv50 of the lithium iron phosphate material is 0.9-1.9 μm.

[0017] In any embodiment, when the battery cell is at 100% SOC, the surface density of the positive electrode active layer is 200-450 mg / 1540.25 mm 2 , optional: 290-350mg / 1540.25mm 2 As a result, the power performance of the battery cell meets the requirements while the energy density of the battery cell is improved.

[0018] In any embodiment, when the battery cell is at 100% SOC, the compaction density of the positive electrode active layer is 2.27-2.67 g / cm 3 , optional: 2.37-2.62g / cm 3 This improves the energy density of the battery cells while meeting the power performance requirements.

[0019] In any embodiment, when the battery cell is at 100% SOC, the surface density of the negative electrode active layer is 100-180 mg / 1540.25 mm 2This improves the energy density of the battery cells while meeting the power performance requirements.

[0020] In any embodiment, when the battery cell is at 100% SOC, the compaction density of the negative electrode active layer is 1.2-1.45 g / cm 3 , optional 1.28-1.44g / cm 3 This improves the energy density of the battery cells while meeting the power performance requirements.

[0021] In any embodiment, the negative electrode material further comprises a silicon material.

[0022] In any embodiment, the silicon-containing material includes one or more of silicon-oxygen compounds and silicon-carbon compounds; and / or,

[0023] Based on the mass of the negative electrode material, the mass percentage of the silicon element is 0.3%-10%, and can be optionally 1%-6%.

[0024] This improves the energy density of battery cells while meeting power performance requirements.

[0025] In any embodiment, the chemical formula of the lithium iron phosphate material is Li x Fe (1-s) M s P y O z , wherein x is greater than or equal to 0.5 and less than or equal to 1.3, s is greater than or equal to 0 and less than 1, y is greater than or equal to 0.5 and less than or equal to 1.3, z is greater than or equal to 3 and less than or equal to 5, and M includes one or more elements selected from B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, Hf, Ni, Co, Ru, Ag, and Pb; and / or,

[0026] The chemical formula of the lithium manganese iron phosphate material is Li x Fe (1-t-s) Mn t M s P y O z, wherein x is greater than or equal to 0.5 and less than or equal to 1.3, t is greater than 0 and less than 1, s is greater than or equal to 0 and less than 1, 1-ts is greater than 0 and less than 1, y is greater than or equal to 0.5 and less than or equal to 1.3, z is greater than or equal to 3 and less than or equal to 5, and M includes one or more elements selected from B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, Hf, Ni, Co, Ru, Ag, and Pb.

[0027] In any embodiment, the powder compaction density of the positive electrode material at 30000N is 2.2-2.8g / cm 3 , optional: 2.3-2.8g / cm 3 .

[0028] In any embodiment, 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.

[0029] In any embodiment, the thickness of the positive electrode conductive layer is 0.5-2 μm.

[0030] In any embodiment, the positive electrode conductive layer includes one or more of a positive electrode conductive agent and a positive electrode binder.

[0031] In any embodiment, the battery cell includes one or more of the following:

[0032] The positive electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers;

[0033] The positive electrode conductive agent at least includes superconducting carbon and carbon nanotubes;

[0034] The positive electrode binder includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid and fluorine-containing acrylic resin.

[0035] In any embodiment, based on the mass of the positive electrode conductive layer, the mass percentage of the positive electrode conductive agent is 30%-50%; and / or,

[0036] Based on the mass of the positive electrode conductive layer, the mass percentage of the positive electrode binder is 50%-70%.

[0037] In any embodiment, the negative electrode plate further includes a negative electrode conductive layer, and the negative electrode conductive layer is disposed between the negative electrode current collector and the negative electrode active layer.

[0038] In any embodiment, the thickness of the negative electrode conductive layer is 0.5-2 μm.

[0039] In any embodiment, the negative electrode conductive layer includes one or more of a negative electrode conductive agent and a negative electrode binder.

[0040] In any embodiment, the negative electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; and / or,

[0041] The negative electrode binder includes one or more of styrene-butadiene rubber, water-soluble unsaturated resin, water-based acrylic resin, polyvinyl alcohol, sodium alginate, and carboxymethyl chitosan.

[0042] In any embodiment, based on the mass of the negative electrode conductive layer, the mass percentage of the negative electrode conductive agent is 20%-40%; and / or,

[0043] Based on the mass of the negative electrode conductive layer, the mass percentage of the negative electrode binder is 60%-80%.

[0044] In any embodiment, the negative electrode active layer is a single-layer or multi-layer structure, and the volume average particle size Dv50 of the negative electrode active material in the negative electrode active layer is 7.5-19.5 μm.

[0045] In any embodiment, the negative electrode active layer is a single-layer structure, and the volume average particle size Dv50 of the negative electrode active material is 8.0-17.5 μm.

[0046] In any embodiment, the negative electrode active layer includes a first negative electrode active layer close to the negative electrode current collector and a second negative electrode active layer disposed on the first negative electrode active layer.

[0047] In any embodiment, the thickness ratio of the second negative electrode active layer to the first negative electrode active layer is 2:8-8:2.

[0048] In any embodiment, the volume average particle size Dv50 of the negative electrode active material in the first negative electrode active layer is 7.5-19.5 μm, and can be 12.5-18.5 μm.

[0049] In any embodiment, the volume average particle size Dv50 of the negative electrode active material in the second negative electrode active layer is 7.5-19.5 μm, and optionally 7.5-15.5 μm.

[0050] In any embodiment, the volume average particle size Dv50 of the negative electrode active material in the second negative electrode active layer is smaller than the volume average particle size Dv50 of the negative electrode active material in the first negative electrode active layer. This is beneficial to improving the power performance of the battery cell, while increasing the energy density of the battery cell and reducing the cost.

[0051] In any embodiment, the graphite in the first negative electrode active layer is selected from one or more of natural graphite and composite graphite; and / or,

[0052] The graphite in the second negative electrode active layer is selected from one or more types of composite graphites.

[0053] In any embodiment, the composite graphite includes a body and a coating layer coated on the surface of the body; the body includes artificial graphite, and the coating layer includes amorphous carbon.

[0054] In any embodiment, the composite graphite includes secondary particles.

[0055] In any embodiment, the powder resistivity of the composite graphite at 8 MPa is 0.01-0.04 Ω·cm.

[0056] In any embodiment, the battery cell further comprises an electrolyte, and at room temperature, the conductivity of the electrolyte is 10-20 mS / cm or 12-17 mS / cm.

[0057] In any embodiment, the volume energy density of the battery cell is 400-550Wh / L or 450-500Wh / L.

[0058] The second aspect of the present application further provides a battery device, comprising the battery cell of the first aspect of the present application; the battery device comprises a battery module, a battery pack or an energy storage device.

[0059] The third aspect of the present application further provides an electrical device, comprising the battery cell of the first aspect of the present application or the battery device of the second aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a schematic diagram of a battery assembly according to one embodiment of the present application.

[0061] Figure 2 It is an exploded view of a battery cell according to one embodiment of the present application.

[0062] Figure 3 It is a schematic diagram of a battery pack according to one embodiment of the present application.

[0063] Figure 4 yes Figure 3An exploded view of a battery pack according to an embodiment of the present application is shown.

[0064] Figure 5 Schematic diagram of an electrical device using a battery pack according to an embodiment of the present application as a power source.

[0065] Description of reference numerals:

[0066] 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

[0067] Below, the embodiments of the battery cells, battery modules, battery packs and electrical devices of the present application are specifically disclosed with appropriate reference to the accompanying drawings. However, there are 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.

[0068] "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.

[0069] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0070] 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.

[0071] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, a 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, a method may also 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.

[0072] [Battery Cell]

[0073] A battery cell, also known as a rechargeable battery or storage battery, refers to a battery that can be recharged to activate the active material after being discharged and continue to be used.

[0074] Normally, a battery cell includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte. During the charge and discharge process of the battery, active ions (such as lithium ions) are embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, and at the same time allow active ions to pass through. The electrolyte is between the positive electrode sheet and the negative electrode sheet, mainly to conduct active ions.

[0075] One embodiment of the present application provides a battery cell, comprising a positive electrode sheet and a negative electrode sheet; wherein:

[0076] The negative electrode sheet comprises 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 comprises a negative electrode material, and the negative electrode material comprises graphite;

[0077] 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 material, and the positive electrode material comprises a positive electrode active material;

[0078] The positive electrode active material comprises a lithium iron manganese phosphate material and a lithium iron phosphate material, wherein the mass proportion of the lithium iron manganese phosphate material in the positive electrode active material is 50%-95%, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or a range consisting of any of the above numerical values; the powder resistivity of the positive electrode material at 12MPa is 5-70Ω·cm, for example, 5Ω·cm, 7Ω·cm, 8Ω·cm, 9Ω·cm, 10Ω·cm, 12Ω·cm, 13Ω·cm, 15Ω·cm, 16Ω·cm , 18Ω·cm, 20Ω·cm, 22Ω·cm, 25Ω·cm, 27Ω·cm, 28Ω·cm, 30Ω·cm, 31Ω·cm, 33Ω·cm, 34Ω·cm, 35Ω·cm, 37Ω·cm, 40Ω·cm, 42Ω·cm, 44 Ω·cm, 45Ω·cm, 48Ω·cm, 50Ω·cm, 53Ω·cm, 55Ω·cm, 57Ω·cm, 60Ω·cm, 62Ω·cm, 65Ω·cm, 67Ω·cm, 68Ω·cm, 70Ω·cm or a range consisting of any of the above values.

[0079] In some embodiments, the positive electrode material may be a powder obtained by calcining and scraping a positive electrode plate, and the powder may contain positive electrode active materials, residual binders, and other materials that have not been completely calcined.

[0080] In some embodiments, the positive electrode material may also be a positive electrode active material, and the positive electrode active material includes a lithium manganese iron phosphate material and a lithium iron phosphate material.

[0081] The present application aims to develop a battery cell with high energy density and good power performance in a low-cost system.

[0082] The platform voltage of lithium iron manganese phosphate material is higher than that of lithium iron phosphate material. Increasing the content of lithium iron manganese phosphate material in the mixed system is beneficial to improving the energy density of the battery cell. However, since the powder resistivity of lithium iron manganese phosphate material is greater than that of lithium iron phosphate material, it is easy to cause the powder resistivity of the mixture of the two to be too large, which deteriorates the power performance of the battery cell. This application controls the ratio of lithium iron manganese phosphate material and lithium iron phosphate material to make the battery cell have a higher energy density, and further improves the power performance of the battery cell while improving the energy density by adjusting the powder resistivity range of the positive electrode material.

[0083] In some embodiments, the mass proportion of the lithium manganese iron phosphate material in the positive electrode active material is 50%-70%.

[0084] This is conducive to improving the energy density and power performance of the battery cell at the same time. In addition, when the mass proportion of lithium iron manganese phosphate material in the positive electrode active material increases within the above range, the energy density of the battery cell is further improved; when the mass proportion of lithium iron manganese phosphate material in the positive electrode active material decreases within the above range, the power performance of the battery cell is further improved.

[0085] In some embodiments, the powder resistivity of the lithium iron manganese phosphate material at 12 MPa is 8-120Ω·cm, which can be optionally 8-80Ω·cm, for example, 8Ω·cm, 10Ω·cm, 20Ω·cm, 23Ω·cm, 25Ω·cm, 30Ω·cm, 32Ω·cm, 35Ω·cm, 38Ω·cm, 40Ω·cm, 45Ω·cm, 50Ω·cm, 60Ω·cm, 70Ω·cm, 80Ω·cm, 90Ω·cm, 100Ω·cm, 110Ω·cm, 120Ω·cm or a range consisting of any of the above values.

[0086] In some embodiments, the volume average particle size Dv50 of the lithium manganese iron phosphate material is 0.1-1.2 μm, and can be optionally 0.2-0.8 μm, for example, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm or a range consisting of any of the above values.

[0087] Therefore, the powder resistivity and volume average particle size Dv50 of the lithium manganese iron phosphate material within the above range is beneficial to improving the energy density of the battery cell while enhancing the power performance of the battery cell.

[0088] In some embodiments, in the lithium manganese iron phosphate material, the molar ratio of manganese atoms to iron atoms is 2:8-8:2, for example, 3:7, 4:6, 5:5, 6:4, 7:3 or a range consisting of any of the above numerical values.

[0089] In some embodiments, the powder resistivity of the lithium iron phosphate material at 12 MPa is 3-100Ω·cm, which can be optionally 3-20Ω·cm, for example, 3Ω·cm, 5Ω·cm, 7Ω·cm, 8Ω·cm, 10Ω·cm, 20Ω·cm, 23Ω·cm, 25Ω·cm, 30Ω·cm, 32Ω·cm, 35Ω·cm, 38Ω·cm, 40Ω·cm, 45Ω·cm, 50Ω·cm, 60Ω·cm, 70Ω·cm, 80Ω·cm, 90Ω·cm, 100Ω·cm or a range consisting of any of the above values.

[0090] In some embodiments, the volume average particle size Dv50 of the lithium iron phosphate material is 0.9-1.9 μm, for example, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm or a range consisting of any of the above values.

[0091] In some embodiments, when the battery cell is at 100% SOC, the surface density of the positive electrode active layer is 200-450 mg / 1540.25 mm 2 , optional: 290-350mg / 1540.25mm 2 , for example 220mg / 1540.25mm 2 、250mg / 1540.25mm 2 、270mg / 1540.25mm 2 、30mg / 1540.25mm 2 、320mg / 1540.25mm 2 、340mg / 1540.25mm 2 、350mg / 1540.25mm 2 、370mg / 1540.25mm 2 、380mg / 1540.25mm 2 , 400mg / 1540.25mm 2 、420mg / 1540.25mm 2 、440mg / 1540.25mm 2 Or any range of the above values. Thus, while the power performance of the battery cell meets the requirements, the energy density of the battery cell is improved.

[0092] In some embodiments, when the battery cell is at 100% SOC, the compaction density of the positive electrode active layer is 2.27-2.67 g / cm 3 , optional: 2.37-2.62g / cm 3 , for example 2.3 g / cm 3 , 2.35g / cm 3 , 2.4g / cm 3 , 2.45g / cm 3 , 2.47g / cm 3 , 2.5g / cm 3 , 2.51g / cm 3 , 2.52g / cm 3 , 2.55g / cm 3 , 2.58g / cm 3 , 2.6g / cm3 , 2.62g / cm 3 , 2.63g / cm 3 , 2.65g / cm 3 , 2.66g / cm 3 Or any range of the above values. Thus, the energy density of the battery cell is improved while meeting the power performance requirements.

[0093] In some embodiments, when the battery cell is at 100% SOC, the surface density of the negative electrode active layer is 100-180 mg / 1540.25 mm 2 , for example 100mg / 1540.25mm 2 、110mg / 1540.25mm 2 、120mg / 1540.25mm 2 、140mg / 1540.25mm 2 、150mg / 1540.25mm 2 、160mg / 1540.25mm 2 、170mg / 1540.25mm 2 、180mg / 1540.25mm 2 Or any range of the above values. Thus, the energy density of the battery cell is improved while meeting the power performance requirements.

[0094] In some embodiments, when the battery cell is at 100% SOC, the compaction density of the negative electrode active layer is 1.2-1.45 g / cm 3 , optional 1.28-1.44g / cm 3 , for example 1.25g / cm 3 , 1.3g / cm 3 , 1.34g / cm 3 , 1.38g / cm 3 , 1.4g / cm 3 , 1.41g / cm 3 , 1.42g / cm 3 , 1.44g / cm 3 Or any range of the above values. Thus, the energy density of the battery cell is improved while meeting the power performance requirements.

[0095] In this application, 100% SOC refers to the highest state in which a battery cell can release energy. There is no unique process for charging a battery cell to 100% SOC. For example, it can be charged at 25°C at a constant current of 0.33C to a charge cutoff voltage, and then charged at the charge cutoff voltage to a state where the current is less than 0.05C.

[0096] In some embodiments, the negative electrode material further comprises a silicon material.

[0097] In some embodiments, the silicon-containing material includes one or more of silicon-oxygen compounds and silicon-carbon compounds; and / or,

[0098] Based on the mass of the negative electrode material, the mass percentage of the silicon element is 0.3%-10%, and can be optionally 1%-6%, for example, 1%, 2%, 3%, 4%, 5%, 6% or a range consisting of any of the above values.

[0099] This improves the energy density of battery cells while meeting power performance requirements.

[0100] In some embodiments, the chemical formula of the lithium iron phosphate material is Li x Fe (1-s) M s P y O z , wherein x is greater than or equal to 0.5 and less than or equal to 1.3 (e.g., 0.5, 0.8, 1, 1.1, 1.2, 1.3, or any range thereof), s is greater than or equal to 0 and less than 1 (e.g., 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, or any range thereof), and y is greater than or equal to 0.5 and less than or equal to 1.3 (e.g., 0.5, 0.6, 0.7, 0.8, 0.9, 1 , 1.1, 1.2, 1.3 or any range consisting of the above values), z is greater than or equal to 3 and less than or equal to 5 (for example, 3, 4, 5 or any range consisting of the above values), and M includes one or more elements selected from B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, Hf, Ni, Co, Ru, Ag, and Pb.

[0101] In some embodiments, the chemical formula of the lithium manganese iron phosphate material is Li x Fe (1-t-s) Mn t M s P y O z, wherein x is greater than or equal to 0.5 and less than or equal to 1.3 (e.g., 0.5, 0.8, 1, 1.1, 1.2, 1.3, or any range thereof), t is greater than or equal to 0 and less than 1 (e.g., 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, or any range thereof), s is greater than or equal to 0 and less than 1 (e.g., 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, or any range thereof), and 1-ts is greater than or equal to 0 and less than 1 (e.g., 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 , 0.7, 0.8, 0.9, 0.95 or any range consisting of the above values), y is greater than or equal to 0.5 and less than or equal to 1.3 (for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3 or any range consisting of the above values), z is greater than or equal to 3 and less than or equal to 5 (for example, 3, 4, 5 or any range consisting of the above values), and M includes one or more elements selected from B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, Hf, Ni, Co, Ru, Ag, and Pb.

[0102] In some embodiments, the powder compaction density of the positive electrode material at 30000N is 2.2-2.8 g / cm 3 , optional: 2.3-2.8g / cm 3 , for example 2.2 g / cm 3 , 2.3g / cm 3 , 2.4g / cm 3 , 2.5g / cm 3 , 2.6g / cm 3 , 2.8g / cm 3 Or any range consisting of the above values.

[0103] In some embodiments, 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.

[0104] In some embodiments, the thickness of the positive electrode conductive layer is 0.5-2 μm, for example, 1 μm.

[0105] In some embodiments, the positive electrode conductive layer includes one or more of a positive electrode conductive agent and a positive electrode binder.

[0106] In some embodiments, the battery cell includes one or more of the following:

[0107] The positive electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers;

[0108] The positive electrode conductive agent at least includes superconducting carbon and carbon nanotubes;

[0109] The positive electrode binder includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid and fluorine-containing acrylic resin.

[0110] In some embodiments, based on the mass of the positive electrode conductive layer, the mass percentage of the positive electrode conductive agent is 30%-50%; and / or,

[0111] Based on the mass of the positive electrode conductive layer, the mass percentage of the positive electrode binder is 50%-70%.

[0112] In some embodiments, the negative electrode plate further includes a negative electrode conductive layer, and the negative electrode conductive layer is disposed between the negative electrode current collector and the negative electrode active layer.

[0113] In some embodiments, the thickness of the negative electrode conductive layer is 0.5-2 μm, for example, 1 μm.

[0114] In some embodiments, the negative electrode conductive layer includes one or more of a negative electrode conductive agent and a negative electrode binder.

[0115] In some embodiments, the negative electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; and / or,

[0116] The negative electrode binder includes one or more of styrene-butadiene rubber, water-soluble unsaturated resin, water-based acrylic resin, polyvinyl alcohol, sodium alginate, and carboxymethyl chitosan.

[0117] In some embodiments, based on the mass of the negative electrode conductive layer, the mass percentage of the negative electrode conductive agent is 20%-40%; and / or,

[0118] Based on the mass of the negative electrode conductive layer, the mass percentage of the negative electrode binder is 60%-80%.

[0119] In some embodiments, the negative electrode active layer is a single-layer or multi-layer structure, and the volume average particle size Dv50 of the negative electrode active material in the negative electrode active layer is 7.5-19.5 μm.

[0120] In some embodiments, the negative electrode active layer is a single-layer structure, and the volume average particle size Dv50 of the negative electrode active material is 8.0-17.5 μm.

[0121] In some embodiments, the negative electrode active layer includes a first negative electrode active layer close to the negative electrode current collector and a second negative electrode active layer disposed on the first negative electrode active layer.

[0122] In some embodiments, the thickness ratio of the second negative electrode active layer to the first negative electrode active layer is 2:8-8:2, for example, 1:1.

[0123] In some embodiments, the volume average particle size Dv50 of the negative electrode active material in the first negative electrode active layer is 7.5-19.5 μm, optionally 12.5-18.5 μm, for example, 8 μm, 8.5 μm, 9 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 13 μm, 13.5 μm, 15 μm, 16 μm, 16.5 μm, 17 μm, 18 μm, 18.5 μm, 19 μm, 19.5 μm or a range consisting of any of the above numerical values.

[0124] In some embodiments, the volume average particle size Dv50 of the negative electrode active material in the second negative electrode active layer is 7.5-19.5 μm, optionally 7.5-15.5 μm, for example, 8 μm, 8.5 μm, 9 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 13 μm, 13.5 μm, 15 μm, 16 μm, 16.5 μm, 17 μm, 18 μm, 18.5 μm, 19 μm, 19.5 μm or a range consisting of any of the above values.

[0125] In some embodiments, the volume average particle size Dv50 of the negative electrode active material in the second negative electrode active layer is smaller than the volume average particle size Dv50 of the negative electrode active material in the first negative electrode active layer. This is beneficial to improving the power performance of the battery cell, while increasing the energy density of the battery cell and reducing the cost.

[0126] In some embodiments, the graphite in the first negative electrode active layer is selected from one or more of natural graphite and composite graphite; and / or,

[0127] The graphite in the second negative electrode active layer is selected from one or more types of composite graphites.

[0128] In some embodiments, the composite graphite includes a body and a coating layer coated on a surface of the body; the body includes artificial graphite, and the coating layer includes amorphous carbon.

[0129] In some embodiments, the composite graphite includes secondary particles.

[0130] In some embodiments, the powder resistivity of the composite graphite at 8 MPa is 0.01-0.04 Ω·cm.

[0131] In some embodiments, the powder compaction density of the composite graphite under a pressure of 20000N is 1.5-1.85g / cm 3 or 1.55-1.75g / cm 3 , for example 1.5g / cm 3 , 1.6g / cm 3 , 1.7g / cm 3 , 1.75g / cm 3 , 1.8g / cm 3 Or any range consisting of the above values.

[0132] In some embodiments, the negative electrode material has a charge capacity of 350-550 mAh / g at a 0.1C rate.

[0133] In some embodiments, the battery cell further includes an electrolyte, and at room temperature, the conductivity of the electrolyte is 10-20 mS / cm or 12-17 mS / cm.

[0134] In some embodiments, the volumetric energy density of the battery cell is 400-550Wh / L or 450-500Wh / L.

[0135] In this application, the mass percentage of silicon in the negative electrode material is tested by conventional methods in the art. For example, the following specific method is used: disassemble the negative electrode sheet of the battery cell, use DMC (dimethyl carbonate) to fully clean the negative electrode sheet, dry and calcine the negative electrode sheet, collect the negative electrode material in the negative electrode active layer, select multiple points (for example, 10-50) in the negative electrode material for testing by SEM-EDS combination instrument, take the average value, and obtain the mass percentage of silicon in the negative electrode material.

[0136] In this application, the powder resistivity of the positive electrode material is tested by conventional methods in the field. For example, the following specific method is used: the positive electrode sheet is obtained after the battery cell is disassembled, the positive electrode sheet is fully cleaned with DMC (dimethyl carbonate) and dried, and the positive electrode material on the positive electrode current collector is collected by scraping powder method after calcination, the powder resistance tester is turned on and the equipment is stable, a certain mass of positive electrode material is weighed and added to the feeding chamber and the depth of the feeding chamber is adjusted, the target pressure is applied according to the target pressure and the area of ​​the cavity in the feeding chamber, and the powder resistivity test result under a certain pressure is collected.

[0137] In the present application, the powder resistivity of the lithium manganese iron phosphate material and the lithium iron phosphate material is tested by conventional methods in the art, for example, by referring to the specific method mentioned above.

[0138] In the present application, the surface density and compaction density of the positive electrode active layer (negative electrode active layer) are tested by conventional methods in the art. For example, the test is performed according to the following specific method:

[0139] Cut and weigh the positive electrode sheet (negative electrode sheet) of a fixed area, weigh and calculate the weight of the positive electrode collector (negative electrode collector) of the same area in advance, and measure the average thickness of the positive active layer (negative active layer) on the positive electrode sheet (negative electrode sheet).

[0140] The surface density of the positive electrode active layer (negative electrode active layer) is obtained by subtracting the weight of the positive electrode collector (negative electrode collector) from the weight of the positive electrode sheet (negative electrode sheet) and then dividing by the fixed area.

[0141] The compaction density of the positive electrode active layer (negative electrode active layer) is obtained by dividing the area density of the positive electrode active layer (negative electrode active layer) by the average thickness of the positive electrode active layer (negative electrode active layer).

[0142] When the battery cell is in the 100% SOC state, the surface density and compaction density of the positive electrode active layer (negative electrode active layer) when the battery cell is in the 100% SOC state are obtained by testing according to the above method.

[0143] In this application, the volume average particle size Dv50 refers to the particle size at which the volume is accumulated by 50% from the small particle size side in the particle size distribution based on the volume of the powder particles. The Dv50 particle size is tested by conventional methods in the art, for example, it can be measured by Malvern 3000 laser particle size analyzer according to the standard process and requirements of GB / T 19077.1-2016 / ISO 13320:2009 particle size distribution laser diffraction method.

[0144] In the present application, the Dv50 particle size of the lithium manganese iron phosphate material and the lithium iron phosphate material is tested using conventional methods in the art, for example, the test can be performed with reference to the above-mentioned specific method.

[0145] In this application, the charge gram capacity of the negative electrode material at a rate of 0.1C is tested using conventional methods in the art. For example, the specific test method is: disassemble the negative electrode sheet coated on both sides of the battery cell, scrape the negative electrode material from one side of the negative electrode collector and weigh it, take multiple negative electrode sheets of the same area to perform the above operation, and take the average weight to obtain the weight m of the negative electrode material on a single side of the negative electrode sheet; use the above single-sided negative electrode sheet of the same area to prepare a button battery, charge it to 4.1V at a rate of 0.1C at 25°C, then charge it to 0.05C at a constant voltage, let it stand for 30 minutes, and then discharge it to 2.5V at a rate of 0.1C. Repeat the charge and discharge twice, and record the last charge capacity as Cn. Divide the last charge capacity Cn by the weight m of the negative electrode material on a single side to get the test result.

[0146] In the present application, the compaction density of the positive electrode material powder is tested by conventional methods in the field. For example, the specific test method is: for the positive electrode plate of the battery cell, DMC (dimethyl carbonate) is used to fully clean the positive electrode plate, and the positive electrode plate is dried and calcined, and then the positive electrode material in the positive electrode active layer is collected. The positive electrode material powder is weighed into the compaction density tester mold. The tester automatically applies the target pressure to the powder until the powder is compacted. According to the cross-sectional area of ​​the mold and the thickness of the powder at this time, the volume of the powder can be calculated. According to compaction density = mass / volume, the powder compaction density result can be measured.

[0147] In this application, positive electrode material refers to the material of the positive electrode active layer collected from the surface of the positive electrode current collector after the positive electrode sheet is cleaned, dried and calcined. Positive electrode material includes positive electrode active material and / or its calcined product, and also includes auxiliary agents and / or its calcined product used to prepare positive electrode sheets. The auxiliary agents include but are not limited to positive electrode binders, positive electrode conductive agents, positive electrode film-forming agents, etc.

[0148] In this application, negative electrode material refers to the material of the negative electrode active layer collected from the surface of the negative electrode current collector after the negative electrode sheet is cleaned, dried and calcined. Negative electrode material includes negative electrode active material and / or its calcined product, and also includes additives and / or its calcined product used to prepare the negative electrode sheet. The additives include but are not limited to negative electrode binders, negative electrode thickeners, negative electrode conductive agents, negative electrode film-forming agents, etc.

[0149] In the present application, the element types in the positive electrode material active material and the powder compaction density of the positive electrode material can be tested when the battery cell is in any state between 0% SOC and 100% SOC. The above state changes of the battery cell basically have no effect on the test results.

[0150] [Positive electrode]

[0151] The battery cell will be accompanied by Li deintercalation and consumption during the charge and discharge process, and the molar content of Li in the battery cell is different when it is discharged to different states. In the list of positive electrode active materials in this application, the molar content of Li is the initial state of the material, that is, the state before feeding. The positive electrode active material is used in the battery system, and the molar content of Li will change after charge and discharge cycles.

[0152] In the list of positive electrode active materials in this application, the molar content of O is only a theoretical value. The release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0153] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0154] 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.).

[0155] In some embodiments, the positive electrode active material may also adopt the positive electrode active material for battery cells that is well known in the art. As an example, the positive electrode active material may also include at least one of the following materials: lithium transition metal oxides and modified compounds thereof. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for battery cells may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium iron oxide (such as Li5NiO4), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 )、LiNi 0.5 Co 0.25Mn 0.25 O2 (also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds, etc.

[0156] In some embodiments, the positive electrode active layer may further 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.

[0157] In some embodiments, the positive electrode active layer may further include a conductive agent. As an 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.

[0158] 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.

[0159] [Negative electrode]

[0160] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0161] 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.).

[0162] In some embodiments, the negative electrode active material may also adopt the negative electrode active material for battery cells known in the art. As an example, the negative electrode active material may also include at least one of the following materials: soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0163] In some embodiments, the negative electrode active 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).

[0164] In some embodiments, the negative electrode active 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.

[0165] In some embodiments, the negative electrode active layer may further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0166] 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.

[0167] [Electrolyte]

[0168] The electrolyte plays a role in 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.

[0169] In some embodiments, the electrolyte is liquid and includes an electrolyte salt and a solvent.

[0170] 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.

[0171] 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.

[0172] 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 properties of the battery cell, such as additives that improve the overcharge performance of the battery cell, additives that improve the high temperature or low temperature performance of the battery cell, etc.

[0173] [Isolation film]

[0174] In some embodiments, the battery cell further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0175] 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. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without special restrictions.

[0176] 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.

[0177] In some embodiments, the battery cell may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0178] 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.

[0179] 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 an example of a battery cell having a square structure.

[0180] In some embodiments, reference Figure 2 , the outer packaging may include a shell 51 and a cover plate 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 cover plate 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.

[0181] 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.

[0182] In the battery module, the plurality of battery cells may be arranged in sequence along the length direction of the battery module. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells may be fixed by fasteners.

[0183] Optionally, the battery module may further include a housing having a receiving space, and a plurality of battery cells are received in the receiving space.

[0184] 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.

[0185] Figure 3 and Figure 4 1 is a battery pack 1 as an example. Figure 3 and Figure 4The 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.

[0186] In addition, the present application also provides an electrical device, which includes at least one of the battery cells, battery modules, or battery packs provided in the present application. The battery cells, battery modules, or battery packs can be used as power sources for electrical devices, or as energy storage units for electrical devices. Electrical devices 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.

[0187] As an electrical device, a battery cell, a battery module or a battery pack can be selected according to its usage requirements.

[0188] 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.

[0189] [Example]

[0190] 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.

[0191] Example 1

[0192] (1) Positive electrode sheet: A positive electrode conductive layer is arranged on both sides of the positive electrode current collector aluminum foil (thickness of 13 μm), and a positive electrode active layer is arranged on the positive electrode conductive layer on both sides. The positive electrode conductive 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 1 μm, and 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 positive electrode conductive layer is 50%. The positive electrode active layer includes positive electrode active materials lithium manganese iron phosphate material (LMFP) and lithium iron phosphate material (LFP) (mass ratio 7:3), binder polyvinylidene fluoride (PVDF), and conductive agent acetylene black, and the mass ratio of the three is 97:2:1.

[0193] (2) Negative electrode sheet: Negative electrode conductive layers are arranged on both sides of the negative electrode current collector copper foil (thickness of 6 μm), and negative electrode active layers are arranged on the negative electrode conductive layers on both sides. The negative electrode conductive layer is 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 to form a film layer with a thickness of 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%. The negative electrode active layer includes an upper layer (away from the current collector) and a lower layer (close to the current collector). The thickness ratio of the two negative electrode active layers is 1:1. The two negative electrode active layers include negative electrode active materials, conductive agent acetylene black, binder styrene butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) in a mass ratio of 96:1:2:1. The Dv50 particle size of the negative electrode active material in the upper layer (layer II) is 12.3μm, and the Dv50 particle size of the negative electrode active material in the lower layer (layer I) is 15.31μm. The negative electrode active materials in the upper and lower layers are a mixture of composite graphite and silicon with a mass ratio of 97:3 (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%), wherein the Dv50 of the composite graphite particles is 15.4μm, and the powder compaction density under a pressure of 20000N is 1.74g / cm 3 .

[0194] The compaction density of the entire negative electrode active layer at 100% SOC of the battery is 1.41 g / cm 3 .

[0195] (3) Isolation film: Polypropylene film with a thickness of 5 μm.

[0196] (4) The electrolyte includes ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC) and LiPF6, and the volume ratio of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) is 1:1:1. The concentration of LiPF6 in the electrolyte is 1 mol / L. The conductivity of the electrolyte at room temperature is 13.1 mS / cm.

[0197] (5) Preparation of battery cells: including stacking positive electrode sheets, separators, and negative electrode sheets to obtain electrode assemblies. The electrode assemblies are added to the outer packaging square aluminum shell (length 600 mm, thickness 19 mm, height 105 mm), and after drying, the electrolyte is injected with an injection coefficient of 2.9 g / Ah. After packaging, high-temperature standing, formation, secondary injection, aging, capacity and other processes, the battery cells are obtained.

[0198] The battery monomer preparation methods of Examples 2-12 and Comparative Examples 1-4 are similar to those of Example 1, and the different parameters are described below and in Table 1.

[0199] Example 10

[0200] In the negative electrode sheet, the negative electrode active materials in the upper and lower layers are a mixture of composite graphite and silicon with a mass ratio of 94:6 (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%), wherein the Dv50 of the composite graphite particles is 15.4μm, and the powder compaction density under a pressure of 20000N is 1.74g / cm 3 The Dv50 particle size of the negative electrode active material in the upper layer was 12.2 μm, and the Dv50 particle size of the negative electrode active material in the lower layer was 15.12 μm.

[0201] The compaction density of the entire negative electrode active layer at 100% SOC of the battery is 1.37 g / cm 3 , surface density is 107mg / 1540.25mm 2 .

[0202] The remaining parameters are shown in Table 1, and the parameters not shown are the same as those in Example 1.

[0203] Embodiment 11

[0204] In the negative electrode sheet, the negative electrode active materials in the upper and lower layers are both composite graphite, the Dv50 particle size of the composite graphite in the lower layer is 15.5 μm, and the Dv50 particle size of the composite graphite in the upper layer is 12.4 μm.

[0205] The compaction density of the entire negative electrode active layer at 100% SOC of the battery is 1.41 g / cm 3 , surface density is 127mg / 1540.25mm 2 .

[0206] The remaining parameters are shown in Table 1, and the parameters not shown are the same as those in Example 1.

[0207] Example 12

[0208] The negative electrode active layer in the negative electrode sheet is a single layer, and the negative electrode active material in the negative electrode active layer is a mixture of composite graphite and silicon with a mass ratio of 97:3 (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%), wherein the Dv50 particle size of the negative electrode active material is 13.81μm, the Dv50 particle size of the composite graphite particles is 15.4μm, and the powder compaction density under a pressure of 20000N is 1.74g / cm 3The remaining parameters are shown in Table 1, and the parameters not shown are the same as those in Example 1.

[0209] The compacted density of the positive electrode materials of Examples 1, 9-12 at 30000N is 2.37 g / cm 3 The compacted density of the positive electrode materials of Examples 2-8 and Comparative Examples 1-4 at 30000N was 2.35 g / cm 3 , 2.42g / cm 3 , 2.32g / cm 3 , 2.49g / cm 3 , 2.25g / cm 3 , 2.36g / cm 3 , 2.43g / cm 3 , 2.53g / cm 3 , 2.48g / cm 3 , 2.31g / cm 3 , 2.35g / cm 3 .

[0210] Parameter Test

[0211] Test of the mass percentage of silicon in the negative electrode material: disassemble the negative electrode sheet of the battery cell, use DMC (dimethyl carbonate) to fully clean the negative electrode sheet, dry and calcine the negative electrode sheet, collect the negative electrode material in the negative electrode active layer, select multiple points (for example, 50) in the negative electrode material for testing through the SEM-EDS combination instrument, take the average value, and obtain the mass percentage of silicon in the negative electrode material. In order to improve the test accuracy, it can also be used in combination with test methods such as ICP-OES.

[0212] The test method of the powder resistivity of the positive electrode material: after the battery cell is disassembled, the positive electrode sheet is obtained. The positive electrode sheet is fully cleaned with DMC (dimethyl carbonate), dried, calcined, and the positive electrode material on the positive electrode collector is collected by the scraping method. After the powder resistance tester is turned on and the equipment is stable, a certain mass of positive electrode material is weighed and added to the feeding chamber and the depth of the feeding chamber is adjusted. The target pressure is applied according to the target pressure and the area of ​​the cavity in the feeding chamber, and the powder resistivity test results under a pressure of 12MPa are collected. The powder resistivity of lithium manganese iron phosphate material and lithium iron phosphate material is tested according to the above method.

[0213] Test method for surface density and compaction density of positive electrode active layer (negative electrode active layer):

[0214] Cut and weigh the positive electrode sheet (negative electrode sheet) of a fixed area, weigh and calculate the weight of the positive electrode collector (negative electrode collector) of the same area in advance, and measure the average thickness of the positive active layer (negative active layer) on the positive electrode sheet (negative electrode sheet).

[0215] The surface density of the positive electrode active layer (negative electrode active layer) is obtained by subtracting the weight of the positive electrode collector (negative electrode collector) from the weight of the positive electrode sheet (negative electrode sheet) and then dividing by the fixed area.

[0216] The compaction density of the positive electrode active layer (negative electrode active layer) is obtained by dividing the area density of the positive electrode active layer (negative electrode active layer) by the average thickness of the positive electrode active layer (negative electrode active layer).

[0217] When the battery cell is in the 100% SOC state, the compaction density of the positive electrode active layer (negative electrode active layer) in the fully charged state of the battery cell is obtained by testing according to the above method. The 100% SOC state of the battery cell can be achieved, for example, by charging the battery cell at 25°C at a constant current of 0.33C to a voltage of 4.1V, and then charging at a constant voltage of 4.1V to a current less than 0.05C.

[0218] The volume average particle size Dv50 refers to the particle size that reaches 50% of the volume cumulatively from the small particle size side in the particle size distribution based on the volume of the powder particles. The Dv50 particle size of the positive electrode material can be measured by Malvern 3000 laser particle size analyzer according to the standard process and requirements of GB / T19077.1-2016 / ISO 13320:2009 particle size distribution laser diffraction method. The Dv50 particle size of lithium manganese iron phosphate material and lithium iron phosphate material is tested according to the above method.

[0219] The test method of charging gram capacity of negative electrode materials at a rate of 0.1C is as follows: disassemble the negative electrode sheets coated on both sides of the battery cell, scrape off the negative electrode material from one side of the negative electrode current collector and weigh it, take 6 negative electrode sheets of the same area to perform the above operation, and take the average weight to obtain the weight m of the negative electrode material on a single side of the negative electrode sheet. Use the above single-sided negative electrode sheets of the same area to prepare button batteries, charge to the upper cutoff voltage at a rate of 0.1C at 25°C, then charge to 0.05C at a constant voltage, let stand for 30 minutes, and discharge to the lower cutoff voltage at a rate of 0.1C. Repeat the charge and discharge twice, and record the last charge capacity as Cn. Divide the last charge capacity Cn by the weight m of the negative electrode material on a single side to obtain the test result.

[0220] The powder compaction density test method of the positive electrode material: For the positive electrode plate of the battery cell, DMC (dimethyl carbonate) is used to fully clean the positive electrode plate, and the positive electrode plate is dried and calcined, and the positive electrode material in the positive electrode active layer is collected. The positive electrode material powder is weighed and placed in the compaction density tester mold. The tester automatically applies the target pressure to the powder until the powder is compacted. The volume of the powder can be calculated based on the cross-sectional area of ​​the mold and the thickness of the powder at this time. According to the compaction density = mass / volume, the powder compaction density result can be measured.

[0221] Battery Cell Test

[0222] (1) Volume energy density test of battery cells:

[0223] Place the battery cell at 25°C, charge it to 4.1V 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 and discharge platform voltage V at this time; use a caliper to measure the length, thickness, and height of the battery cell (generally calculated based on the outer shell size of the battery cell, excluding the height of the electrode terminals and the insulating film outside the outer shell), and calculate the volume of the battery cell V0; the volume energy density of the battery cell VED = (A0×V) / V0, unit Wh / L.

[0224] (2) Discharge internal resistance DCR test of battery cells:

[0225] At 25°C, the battery cell was charged to 4.1V at a constant current of 0.33C, charged to 0.05C at a constant voltage, left to stand for 30 minutes, and discharged to 2.0V at a constant current of 0.33C. The charge and discharge were repeated three times, and the third discharge capacity was taken as the capacity Cn of the battery cell.

[0226] After the above discharge is completed, charge at a constant current of 0.33Cn to a capacity of 0.5Cn (i.e., charge to 50% SOC), let stand for 60 minutes, and record the voltage after stabilization as V0. Then, discharge at a rate of 2Cn for 10s at 25°C, and take the voltage V1 and discharge current Ic at the 10th second.

[0227] DCR for 50% SOC and 2C discharge for 10s = (V1-V0) / Ic, in mΩ.

[0228] Discharge power = V min ×(OCVdis-V min ) / DCR;

[0229] Among them, V min is the lower limit voltage 2V allowed during the discharge process, and OCVdis is the open circuit voltage value during discharge. Therefore, the discharge power is negatively correlated with the discharge DCR.

[0230] In the following table, the chemical formula of the lithium iron manganese phosphate material also includes the M1 element in addition to Li, Fe, and Mn. The mass content of the M1 element in the lithium iron manganese phosphate material is trace, so it is not expressed in its chemical formula, but it is still considered that the M1 element is included in the lithium iron manganese phosphate material shown in the table. The sum of the subscripts of Fe and Mn in the chemical formula of the lithium iron manganese phosphate material and the total number of moles of the M1 element in the chemical formula is 1. The chemical formula of the lithium iron phosphate material also includes the M2 element in addition to Li and Fe. The mass content of the M2 element in the lithium iron phosphate material is trace, so it is not expressed in its chemical formula, but it is still considered that the M2 element is included in the lithium iron phosphate material shown in the table. The sum of the subscript of Fe in the chemical formula of the lithium iron phosphate material and the total number of moles of the M2 element in the chemical formula is 1. The M1 element and the M2 element may be the same or different.

[0231]

[0232]

[0233] It can be seen from the above table:

[0234] Compared with Comparative Example 1 in which the positive electrode active material only includes lithium iron phosphate material, the energy density of the battery cells of Examples 1 to 12 of the present application is significantly improved.

[0235] Compared with Comparative Example 2 in which the mass proportion of lithium manganese iron phosphate in the positive electrode active material is too low, the energy density of the battery cells in Examples 1-12 of the present application is significantly improved.

[0236] Compared with Comparative Example 3 in which the positive electrode active material only includes lithium iron manganese phosphate material, the power performance of the battery cells of Examples 1 to 12 of the present application is significantly improved.

[0237] Compared with the positive electrode material of Comparative Example 4, whose powder resistivity of 12 MPa is too high, the power performance of the battery cells of Examples 1-12 is significantly improved.

[0238] Compared with Example 1, Examples 2 and 4 of the present application increase the mass proportion of lithium manganese iron phosphate in the positive electrode active material, which can improve the energy density of the battery cell.

[0239] Compared with Example 1, Example 3 of the present application reduces the mass proportion of lithium manganese iron phosphate in the positive electrode active material, which can improve the power performance of the battery cell.

[0240] Compared with Example 1, Examples 5 and 8 of the present application reduce the powder resistivity of the positive electrode material and reduce the manganese-iron molar ratio of the lithium manganese iron phosphate material, which can improve the power performance of the battery cell.

[0241] Compared with Example 1, Examples 6 and 7 of the present application increase the powder resistivity of the positive electrode material and increase the manganese-iron molar ratio of the lithium manganese iron phosphate material, which can increase the energy density of the battery cell.

[0242] Compared with Example 1, Example 9 of the present application simultaneously improves the surface density of the positive electrode active layer and the negative electrode active layer at 100% SOC of the battery, which can improve the energy density of the battery cell.

[0243] Compared with Example 1, Example 10 of the present application increases the mass proportion of silicon element in the negative electrode active material, which can improve the energy density of the battery cell.

[0244] Compared with Example 1, the negative electrode active material of Example 11 of the present application does not include silicon element, which can improve the power performance of the battery cell.

[0245] Compared with Example 12, Example 1 of the present application adopts a double-layer negative electrode active layer, which is beneficial to improving the power performance of the battery cell.

[0246] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A battery cell, comprising a positive electrode sheet and a negative electrode sheet, wherein: The negative electrode sheet comprises 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 comprises a negative electrode material, and the negative electrode material comprises graphite; The positive electrode sheet includes a positive electrode current collector and a positive electrode active layer disposed on at least one side of the positive electrode current collector, the positive electrode active layer includes a positive electrode material, and the positive electrode material includes a positive electrode active material. The positive electrode active material comprises lithium iron manganese phosphate material and lithium iron phosphate material, the mass proportion of the lithium iron manganese phosphate material in the positive electrode active material is 50%-95%, and the powder resistivity of the positive electrode material at 12 MPa is 5-70Ω·cm.

2. The battery cell according to claim 1, wherein: The mass proportion of the lithium iron manganese phosphate material in the positive electrode active material is 50%-70%.

3. The battery cell according to claim 1 or 2, wherein: The powder resistivity of the lithium iron manganese phosphate material at 12 MPa is 8-120 Ω·cm, and can be optionally 8-80 Ω·cm.

4. The battery cell according to any one of claims 1 to 3, wherein: The volume average particle size Dv50 of the lithium manganese iron phosphate material is 0.1 μm-1.2 μm, and can be optionally 0.2 μm-0.8 μm.

5. The battery cell according to any one of claims 1 to 4, wherein: In the lithium manganese iron phosphate material, the molar ratio of manganese atoms to iron atoms is 2:8-8:

2.

6. The battery cell according to any one of claims 1 to 5, wherein: The powder resistivity of the lithium iron phosphate material at 12 MPa is 3-100 Ω·cm, and can be optionally 3-20 Ω·cm.

7. The battery cell according to any one of claims 1 to 6, wherein: The volume average particle size Dv50 of the lithium iron phosphate material is 0.9-1.9 μm.

8. The battery cell according to any one of claims 1 to 7, wherein: When the battery cell is in the 100% SOC state, the surface density of the positive electrode active layer is 200-450 mg / 1540.25 mm 2 , optional: 290-350mg / 1540.25mm 2 .

9. The battery cell according to any one of claims 1 to 8, wherein: The battery cell is in the 100% SOC state, and the compaction density of the positive electrode active layer is 2.27-2.67 g / cm 3 , optional: 2.37-2.62g / cm 3 .

10. The battery cell according to any one of claims 1 to 9, wherein: When the battery cell is in the 100% SOC state, the surface density of the negative electrode active layer is 100-180 mg / 1540.25 mm 2 .

11. The battery cell according to any one of claims 1 to 10, wherein: The battery cell is in the 100% SOC state, and the compaction density of the negative electrode active layer is 1.2-1.45 g / cm 3 , optional 1.28-1.44g / cm 3 .

12. The battery cell according to any one of claims 1 to 11, wherein: The negative electrode material further comprises silicon material.

13. The battery cell according to claim 12, wherein: The silicon-containing material includes one or more of silicon-oxygen compounds and silicon-carbon compounds; and / or, Based on the mass of the negative electrode material, the mass percentage of the silicon element is 0.3%-10%, and can be optionally 1%-6%.

14. The battery cell according to any one of claims 1 to 13, wherein: The chemical formula of the lithium iron phosphate material is Li x Fe (1-s) M s P y O z , wherein x is greater than or equal to 0.5 and less than or equal to 1.3, s is greater than or equal to 0 and less than 1, y is greater than or equal to 0.5 and less than or equal to 1.3, z is greater than or equal to 3 and less than or equal to 5, and M includes one or more elements selected from B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, Hf, Ni, Co, Ru, Ag, and Pb; and / or, The chemical formula of the lithium manganese iron phosphate material is Li x Fe (1-t-s) Mn t M s P y O z , wherein x is greater than or equal to 0.5 and less than or equal to 1.3, t is greater than 0 and less than 1, s is greater than or equal to 0 and less than 1, 1-ts is greater than 0 and less than 1, y is greater than or equal to 0.5 and less than or equal to 1.3, z is greater than or equal to 3 and less than or equal to 5, and M includes one or more elements selected from B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, Hf, Ni, Co, Ru, Ag, and Pb.

15. The battery cell according to any one of claims 1 to 14, wherein: The powder compaction density of the positive electrode material at 30000N is 2.2-2.8g / cm 3 , optional: 2.3-2.8g / cm 3 .

16. The battery cell according to any one of claims 1 to 15, 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.

17. The battery cell according to claim 16, wherein: The thickness of the positive electrode conductive layer is 0.5-2 μm.

18. The battery cell according to claim 16 or 17, wherein: The positive electrode conductive layer includes one or more of a positive electrode conductive agent and a positive electrode binder.

19. The battery cell according to claim 18, characterized in that One or more of the following: The positive electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; The positive electrode conductive agent at least includes superconducting carbon and carbon nanotubes; The positive electrode binder includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid and fluorine-containing acrylic resin.

20. The battery cell according to claim 18 or 19, wherein: Based on the mass of the positive electrode conductive layer, the mass percentage of the positive electrode conductive agent is 30%-50%; and / or, Based on the mass of the positive electrode conductive layer, the mass percentage of the positive electrode binder is 50%-70%.

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

22. The battery cell according to claim 21, wherein: The thickness of the negative electrode conductive layer is 0.5-2 μm.

23. The battery cell according to claim 21 or 22, wherein: The negative electrode conductive layer includes one or more of a negative electrode conductive agent and a negative electrode binder.

24. The battery cell according to claim 23, wherein: The negative electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; and / or, The negative electrode binder includes one or more of styrene-butadiene rubber, water-soluble unsaturated resin, water-based acrylic resin, polyvinyl alcohol, sodium alginate, and carboxymethyl chitosan.

25. The battery cell according to claim 23 or 24, wherein: Based on the mass of the negative electrode conductive layer, the mass percentage of the negative electrode conductive agent is 20%-40%; and / or, Based on the mass of the negative electrode conductive layer, the mass percentage of the negative electrode binder is 60%-80%.

26. The battery cell according to any one of claims 1 to 25, wherein: The negative electrode active layer is a single-layer or multi-layer structure, and the volume average particle size Dv50 of the negative electrode material in the negative electrode active layer is 7.5-19.5 μm.

27. The battery cell according to any one of claims 1 to 26, wherein: The negative electrode active layer is a single-layer structure, and the volume average particle size Dv50 of the negative electrode material is 8.0-17.5 μm.

28. The battery cell according to any one of claims 1 to 27, wherein: The negative electrode active layer includes a first negative electrode active layer close to the negative electrode current collector and a second negative electrode active layer disposed on the first negative electrode active layer.

29. The battery cell according to claim 28, wherein: The thickness ratio of the second negative electrode active layer to the first negative electrode active layer is 2:8-8:

2.

30. The battery cell according to claim 28 or 29, wherein: The volume average particle size Dv50 of the negative electrode active material in the first negative electrode active layer is 7.5-19.5 μm, and can be 12.5-18.5 μm.

31. The battery cell according to any one of claims 28 to 30, wherein: The volume average particle size Dv50 of the negative electrode active material in the second negative electrode active layer is 7.5-19.5 μm, and can be 7.5-15.5 μm.

32. The battery cell according to any one of claims 28 to 31, wherein: The volume average particle size Dv50 of the negative electrode active material in the second negative electrode active layer is smaller than the volume average particle size Dv50 of the negative electrode active material in the first negative electrode active layer.

33. The battery cell according to any one of claims 28 to 32, wherein: The graphite in the first negative electrode active layer is selected from one or more of natural graphite and composite graphite; and / or, The graphite in the second negative electrode active layer is selected from one or more types of composite graphites.

34. The battery cell according to claim 33, wherein: The composite graphite comprises a main body and a coating layer coated on the surface of the main body; the main body comprises artificial graphite, and the coating layer comprises amorphous carbon.

35. The battery cell according to claim 33 or 34, wherein: The composite graphite includes secondary particles.

36. The battery cell according to any one of claims 33 to 35, wherein: The powder resistivity of the composite graphite at 8 MPa is 0.01-0.04 Ω·cm.

37. The battery cell according to any one of claims 1 to 36, wherein: The battery cell also includes an electrolyte, and the conductivity of the electrolyte at room temperature is 10-20 mS / cm, and can be optionally 12-17 mS / cm.

38. The battery cell according to any one of claims 1 to 37, wherein: The volume energy density of the battery cell is 400-550Wh / L, and can be optionally 450-500Wh / L.

39. A battery device comprising the battery cell according to any one of claims 1 to 38; the battery device comprises a battery module, a battery pack or an energy storage device.

40. An electrical device comprising the battery cell according to any one of claims 1 to 38 or the battery device according to claim 39.

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