Battery cell, battery device and electric device

Abstract

A battery cell, a battery device, and an electric device. The battery cell comprises an electrode assembly, and the electrode assembly comprises a positive electrode sheet, a negative electrode sheet and a non-aqueous electrolyte; the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer, and the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer; and the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises a lithium iron manganese phosphate material and a lithium nickel cobalt manganese oxide material. In the lithium nickel cobalt manganese oxide material, the molar proportion of Ni in the sum of the three elements Ni, Co and Mn is 0.5-0.95. The non-aqueous electrolyte comprises vinylene carbonate, and the mass content of vinylene carbonate in the non-aqueous electrolyte is 0.5% -2%; and the non-aqueous electrolyte comprises at least one of linear carbonate and linear carboxylate, and the conductivity of the non-aqueous electrolyte is 9-14 mS / cm. The energy density, cycling performance and power performance of the battery cell are all improved.

Description

Battery cell, battery device, and power consuming device

[0001] This application is based on Chinese Patent Application No. 202411291532.5, filed on September 14, 2024, and Chinese Patent Application No. 202411088472.7, filed on August 8, 2024, for which priority is claimed, and the contents of all of the aforementioned applications are hereby incorporated by reference in their entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a battery cell, a battery device, and a power consuming device. BACKGROUND

[0003] In recent years, as the application range of batteries is more and more extensive, batteries are widely used in energy storage power supply systems such as hydroelectric, thermal, wind and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. As batteries have made great progress, higher requirements have been put forward for their energy density, cycle performance, etc. SUMMARY

[0004] The present application is made in view of the above-mentioned problems, and aims to provide a battery cell, a battery device, and a power consuming device. The energy density, cycle performance and power performance of the battery cell of the present application are simultaneously improved.

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides a battery cell, comprising an electrode assembly and a non-aqueous electrolyte, the electrode assembly comprising a positive electrode sheet and a negative electrode sheet; the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer located on at least one side of the positive electrode current collector, and the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer located on at least one side of the negative electrode current collector; wherein,

[0006] The positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises a lithium manganese iron phosphate material and a lithium nickel cobalt manganese oxide material; in the lithium nickel cobalt manganese oxide material, the molar percentage of Ni element in the total of Ni, Co and Mn elements is 0.5-0.95;

[0007] The non-aqueous electrolyte comprises vinylene carbonate, and the mass content of the vinylene carbonate in the non-aqueous electrolyte is 0.5%-2%;

[0008] The non-aqueous electrolyte comprises at least one of a linear carbonate and a linear carboxylate, and the conductivity of the non-aqueous electrolyte is 9-14 mS / cm.

[0009] Therefore, the non-aqueous electrolyte of the application includes a certain amount of vinylene carbonate, which is conducive to forming stable components on the surface of the negative electrode to improve the stability of the SEI film of the negative electrode and reduce the impedance of the SEI film. At the same time, the conductivity of the electrolyte is within a certain range, which is conducive to making up for the power loss caused by the increase in the impedance of the SEI film, and is also conducive to making up for the rate loss caused by the mixing of the manganese iron phosphate material, and is also conducive to reducing the negative impact of excessively high conductivity on high-temperature cycle performance, ensuring that the battery has high energy density while improving the cycle performance and power performance of the battery.

[0010] In any embodiment, the non-aqueous electrolyte includes a linear carbonate, the linear carbonate includes dimethyl carbonate, and the mass content of the dimethyl carbonate in the non-aqueous electrolyte is 4%-20% or 8%-16%. Therefore, by adjusting the conductivity of the electrolyte with a certain amount of dimethyl carbonate, it is conducive to improving the power performance of the battery while ensuring the high-temperature cycle performance of the battery.

[0011] In any embodiment, the non-aqueous electrolyte includes a linear carboxylic acid ester, and the mass content of the linear carboxylic acid ester in the non-aqueous electrolyte is 5%-25%.

[0012] In any embodiment, the linear carboxylic acid ester includes at least one of methyl formate, methyl acetate, ethyl formate, and ethyl acetate.

[0013] Therefore, by adjusting the conductivity of the electrolyte with a certain amount of linear carboxylic acid ester, it is conducive to improving the power performance of the battery while ensuring the high-temperature cycle performance of the battery.

[0014] In any embodiment, the viscosity of the non-aqueous electrolyte at room temperature is 1-3 mPa·s or 2-3 mPa·s.

[0015] In any embodiment, when the mass proportion of the nickel-cobalt-manganese acid lithium material in the positive electrode active material is ≥10%, the non-aqueous electrolyte further includes a substance containing a sulfur-oxygen bond, and the substance containing the sulfur-oxygen bond includes at least one of vinyl sulfate and 1,3-propanesulfonic acid lactone.

[0016] In any embodiment, the mass content of the substance containing the sulfur-oxygen bond in the non-aqueous electrolyte is 0.5%-4% or 0.5%-2%.

[0017] Therefore, when the mass proportion of the nickel-cobalt-manganese acid lithium material in the positive electrode active material is ≥10%, in order to take advantage of the capacity of the nickel-cobalt-manganese acid lithium material, the upper limit voltage of the battery is based on the nickel-cobalt-manganese acid lithium material, and the substance containing the sulfur-oxygen bond is formed on the positive electrode under high voltage, which optimizes the composition of the positive electrode interfacial film, inhibits the side reaction between the surface residual alkali of the nickel-cobalt-manganese acid lithium material and the acidic substances in the electrolyte, and improves the cycle performance of the battery.

[0018] In any embodiment, the mass ratio of the 1,3-propanesultone to the vinyl sulfate in the non-aqueous electrolyte is greater than 0 and less than 1.

[0019] In this way, the mass of the vinyl sulfate being greater than the mass of the 1,3-propanesultone can reduce the impedance of the positive electrode interface film and improve the power performance of the battery.

[0020] In any embodiment, the non-aqueous electrolyte further comprises a lithium salt, and the mass content of the lithium salt in the non-aqueous electrolyte is 12%-16%.

[0021] In any embodiment, when the mass ratio of the nickel cobalt manganese lithium material in the positive electrode active material is ≥20%, the lithium salt comprises lithium hexafluorophosphate and a lithium fluorosulfonamide salt, and the lithium fluorosulfonamide salt comprises at least one of lithium monofluorosulfonimide, lithium bifluorosulfonimide, and lithium trifluorosulfonimide.

[0022] In this way, the inclusion of lithium hexafluorophosphate and a lithium fluorosulfonamide salt in the non-aqueous electrolyte can improve the heat resistance temperature of the electrolyte, thereby reducing the risk of positive electrode thermal runaway caused by electrolyte heat resistance.

[0023] In any embodiment, the lithium salt comprises lithium hexafluorophosphate and lithium bifluorosulfonimide, and the mass ratio of the lithium hexafluorophosphate to the lithium bifluorosulfonimide is 1.23:1-4.28:1.

[0024] In this way, the ratio of lithium hexafluorophosphate to lithium bifluorosulfonimide within the above range can on the one hand reduce the risk of positive electrode thermal runaway caused by electrolyte heat resistance, and on the other hand reduce the negative impact of lithium bifluorosulfonimide on the safety performance of the negative electrode, thereby improving the safety performance of the battery.

[0025] In any embodiment, the non-aqueous electrolyte further comprises vinyl carbonate, and the mass content of the vinyl carbonate in the non-aqueous electrolyte is 12%-35%.

[0026] In this way, on the one hand, the inclusion of vinyl carbonate in the non-aqueous electrolyte is conducive to reducing the impedance of the interface film, ensuring the cycle performance of the battery while improving the power performance of the battery; on the other hand, the above content can inhibit the side reaction of vinyl carbonate with the positive electrode active material, thereby improving the cycle performance and safety performance of the battery.

[0027] In any embodiment, the mass ratio of Ni element in the positive electrode film layer is 5.1%-25%, the mass ratio of Fe element in the positive electrode film layer is 6%-15%, and the mass content of the vinylene carbonate in the non-aqueous electrolyte is 1%-1.5%.

[0028] In any embodiment, the mass percentage of the lithium manganese iron phosphate material in the positive electrode active material is 50%-90%.

[0029] Therefore, when the mass percentage of the lithium manganese iron phosphate material in the positive electrode film layer is high, the platform voltage and the energy density are improved, but manganese ions are easily dissolved and enriched on the surface of the negative electrode SEI film, leading to intensified side reactions, increased gas production, and affected cycle performance of the battery. By adjusting the content of vinylene carbonate in the electrolyte within the above range, the stability of the components of the negative electrode SEI film is improved, thereby improving the cycle performance of the battery.

[0030] In any embodiment, the mass percentage of the lithium manganese iron phosphate material in the positive electrode active material is 60%-80%; and in the lithium nickel cobalt manganese oxide material, the molar percentage of Ni element in the total of Ni, Co, and Mn elements is 0.7-0.95.

[0031] Therefore, while maintaining the cost advantage, the battery has good energy density and cycle performance.

[0032] In any embodiment, the lithium manganese iron phosphate material further comprises one or more elements selected from Al, B, Ca, Cr, K, Mg, Ni, Co, Na, Si, Ti, V, Cu, Zn, S, Sc, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, Cl, C, N, F.

[0033] In any embodiment, the lithium manganese iron phosphate material comprises one or more of the following:

[0034] The mass percentage of Al element in the lithium manganese iron phosphate material is 0.01%-0.03%;

[0035] The mass percentage of Ca element in the lithium manganese iron phosphate material is 0.005%-0.02%;

[0036] The mass percentage of Cr element in the lithium manganese iron phosphate material is 0.0018%-0.004%;

[0037] The mass percentage of Cu element in the lithium manganese iron phosphate material is 0.00275%-0.006%;

[0038] The mass percentage of Fe element in the lithium manganese iron phosphate material is 6.955%-14%;

[0039] The mass percentage of K element in the lithium manganese iron phosphate material is 0.00045%-0.001%;

[0040] a mass percentage of Li in the lithium manganese iron phosphate material is 3%-4.5%;

[0041] a mass percentage of Mg in the lithium manganese iron phosphate material is 0.003%-0.007%;

[0042] a mass percentage of Mn in the lithium manganese iron phosphate material is 9.86%-20%;

[0043] a mass percentage of Na in the lithium manganese iron phosphate material is 0.016%-0.04%;

[0044] a mass percentage of P in the lithium manganese iron phosphate material is 9.65%-20%;

[0045] a mass percentage of Si in the lithium manganese iron phosphate material is 0.00125%-0.003%;

[0046] a mass percentage of Ti in the lithium manganese iron phosphate material is 0.023%-0.05%;

[0047] a mass percentage of V in the lithium manganese iron phosphate material is 0.0845%-0.18%;

[0048] a mass percentage of Zn in the lithium manganese iron phosphate material is 0.00115%-0.003%.

[0049] In any embodiment, the lithium nickel cobalt manganese oxide material further comprises one or more of Al, B, Fe, Sr, Ti, Y, Zr, Na, K, Mg, Si, P, S, Ca, Sc, V, Cr, Cu, Zn, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, F.

[0050] In any embodiment, the lithium nickel cobalt manganese oxide material comprises one or more of:

[0051] a mass percentage of Al in the lithium nickel cobalt manganese oxide material is 0.0315%-0.07%;

[0052] a mass percentage of B in the lithium nickel cobalt manganese oxide material is 0.00195%-0.005%;

[0053] a mass percentage of Co in the lithium nickel cobalt manganese oxide material is 3.825%-8%;

[0054] a mass percentage of Fe in the lithium nickel cobalt manganese oxide material is 0.0016%-0.004%;

[0055] The mass percentage of Li element in the lithium nickel cobalt manganese oxide material is 5.5%-6.8%;

[0056] The mass percentage of Mn element in the lithium nickel cobalt manganese oxide material is 1.22%-2.8%;

[0057] The mass percentage of Ni element in the lithium nickel cobalt manganese oxide material is 24.93%-51%;

[0058] The mass percentage of Sr element in the lithium nickel cobalt manganese oxide material is 0.00005%-0.0002%;

[0059] The mass percentage of Ti element in the lithium nickel cobalt manganese oxide material is 0.00015%-0.0004%;

[0060] The mass percentage of Y element in the lithium nickel cobalt manganese oxide material is 0.0004%-0.0009%;

[0061] The mass percentage of Zr element in the lithium nickel cobalt manganese oxide material is 0.128%-0.3%.

[0062] In any embodiment, the lithium nickel cobalt manganese oxide material comprises spherical particles, and the lithium iron manganese phosphate material comprises particles with a shape suitable for filling the gaps between the spherical particles. In this way, the compaction density of the positive electrode active material is improved, thereby improving the energy density of the battery.

[0063] In any embodiment, the lithium nickel cobalt manganese oxide material is a polycrystalline material. In this way, the use of a polycrystalline lithium nickel cobalt manganese oxide material is beneficial to improve the power of the battery.

[0064] In any embodiment, the lithium nickel cobalt manganese oxide material comprises particles with a longest diameter of 4-8 μm and particles with a longest diameter of 0.5-2 μm. In this way, the combination of different particle sizes of lithium nickel cobalt manganese oxide particles is beneficial to improve the compaction density of the positive electrode active material and improve the energy density of the battery.

[0065] In any embodiment, the lithium iron manganese phosphate material comprises particles with a longest diameter of 0.1-0.3 μm and particles with a longest diameter of 1-2 μm. In this way, the combination of different particle sizes of lithium iron manganese phosphate particles is beneficial to improve the compaction density of the positive electrode active material and improve the energy density of the battery.

[0066] In any embodiment, the positive electrode film layer further comprises a lithium supplement material, and the lithium supplement material comprises one or more of lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganate, lithium tartrate, and trilithium citrate. In this way, it is beneficial to improve the energy density of the battery.

[0067] In any embodiment, the negative electrode film layer comprises a negative electrode active material, the negative electrode active material comprises graphite and a silicon material, and the mass percentage of silicon element in the negative electrode film layer is 0.3%-10%. This is beneficial to improve the energy density of the battery.

[0068] In any embodiment, the silicon material comprises one or more of silicon oxide and silicon-carbon composite.

[0069] In any embodiment, the silicon material comprises silicon-carbon composite, and the mass percentage of silicon element in the negative electrode film layer is 1%-5%. This is beneficial to improve the energy density of the battery.

[0070] In any embodiment, the areal density of the positive electrode film layer is 0.32-0.36 mg / 1540.25 mm 2 .

[0071] In any embodiment, the areal density of the negative electrode film layer is 0.169-0.190 mg / 1540.25 mm 2 .

[0072] This is beneficial to improve the energy density of the battery.

[0073] In any embodiment, the ratio of the size of the positive electrode film layer in the first direction to the size of the battery monomer in the first direction is ≥92%.

[0074] In any embodiment, the ratio of the size of the positive electrode film layer in the second direction to the size of the battery monomer in the second direction is ≥93%, and the second direction (y) is perpendicular to the first direction.

[0075] This is beneficial to improve the utilization rate of the electrode assembly.

[0076] In any embodiment, in the battery monomer configured as a 0% SOC state, the thickness ratio of the positive electrode film layer on any one side of the positive electrode current collector to the positive electrode current collector is 5-8.

[0077] In any embodiment, in the battery monomer configured as a 0% SOC state, the thickness ratio of the negative electrode film layer on any one side of the negative electrode current collector to the negative electrode current collector is 13-20.

[0078] This simultaneously improves the energy density and kinetic performance of the battery.

[0079] In any embodiment, the negative electrode film layer comprises a first negative electrode film layer on the negative electrode current collector and a second negative electrode film layer on the first negative electrode film layer, and the first negative electrode film layer and the second negative electrode film layer comprise graphite. This further improves the kinetic performance of the battery.

[0080] In any embodiment, the thickness of the positive current collector is 10-13 μm.

[0081] In any embodiment, the thickness of the negative current collector is 4-5.5 μm.

[0082] Thus, the energy density of the battery is improved.

[0083] In any embodiment, the electrode assembly comprises at least two positive electrode sheets and at least two negative electrode sheets, the positive electrode sheets and the negative electrode sheets are stacked; the positive electrode sheet and / or the negative electrode sheet comprises a tab portion and a main body portion, the tab portion extends from the main body portion along a first direction, the ratio of the total size L1 of the joint area of the tab portion and the main body portion in a second direction to the size L of the main body portion in the second direction is ≥ 50%, and the second direction is perpendicular to the first direction.

[0084] In any embodiment, the battery cell comprises at least two poles of the same polarity, and the poles are directly electrically connected with the tab portion of the corresponding polarity.

[0085] In any embodiment, the battery cell comprises two positive poles and two negative poles, the two positive poles are respectively arranged on the two sides of the battery cell perpendicular to the first direction, the two negative poles are respectively arranged on the two sides of the battery cell perpendicular to the first direction, and the positive poles and the negative poles are oppositely arranged along the first direction.

[0086] Thus, the direct current impedance of the battery is reduced, the overcurrent area of the battery is increased, and the fast charging performance of the battery is improved.

[0087] In any embodiment, the size of the electrode assembly in the first direction is 400-1000 mm.

[0088] In any embodiment, the size of the electrode assembly in the second direction is 90-120 mm, and the second direction is perpendicular to the first direction.

[0089] In any embodiment, the size of the electrode assembly in the third direction is 13-25 μm, and the third direction is perpendicular to both the first direction and the second direction.

[0090] Thus, while ensuring the fast charging performance of the battery, the energy density of the battery is improved.

[0091] In any embodiment, the discharge platform voltage of the battery cell from 4.25 V to 2.0 V at 1 / 3 C is 3.574-3.63 V or 3.595-3.63 V.

[0092] Thus, the platform voltage of the battery is improved, and the energy density of the battery is improved.

[0093] In any embodiment, the energy density of the battery cell is 210-250 Wh / kg.

[0094] In any embodiment, the upper limit voltage of the battery cell at room temperature is 4.2-4.3 V. Thus, the energy density of the battery is improved.

[0095] The second aspect of the application also provides a battery device comprising the battery cell of the first aspect of the application; the battery device comprises a battery module, a battery pack or an energy storage device.

[0096] The third aspect of the application provides a power consumption device comprising the battery cell of the first aspect of the application or the battery device of the second aspect of the application.

[0097] In any embodiment, the power consumption device is a vehicle, and the length direction of the battery cell or the battery device is parallel to the driving direction of the vehicle.

[0098] The application also relates to the following aspects:

[0099] 1. A battery cell comprising an electrode assembly, the electrode assembly comprising a positive electrode sheet, a negative electrode sheet and a non-aqueous electrolyte; the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer located on at least one side of the positive electrode current collector, the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer located on at least one side of the negative electrode current collector; wherein,

[0100] The positive electrode film layer comprises a positive electrode active material, the positive electrode active material comprises a lithium manganese iron phosphate material and a lithium nickel cobalt manganese oxide material; in the lithium nickel cobalt manganese oxide material, the molar proportion of Ni element in the total of Ni, Co and Mn elements is 0.5-0.95;

[0101] The non-aqueous electrolyte comprises a chain ester compound and a vinylene carbonate, the mass content of the chain ester compound in the non-aqueous electrolyte is 4%-16%, and the mass content of the vinylene carbonate in the non-aqueous electrolyte is 0.5%-2%.

[0102] 2. The battery cell according to the first aspect, the mass content of the chain ester compound in the non-aqueous electrolyte is 8%-16%.

[0103] 3. The battery cell according to the first or second aspect, the viscosity of the non-aqueous electrolyte at 25°C is 1-3 mPa·s or 2-3 mPa·s.

[0104] 4. The battery cell according to any one of aspects 1 to 3, wherein the nonaqueous electrolyte has an electrical conductivity of 9-14 mS / cm.

[0105] 5. The battery cell according to any one of aspects 1 to 4, wherein the chain ester compound comprises one or more of a chain carbonate and a chain carboxylate.

[0106] 6. The battery cell according to any one of aspects 1 to 5, wherein the chain ester compound comprises one or more of dimethyl carbonate and ethyl methyl carbonate.

[0107] 7. The battery cell according to any one of aspects 1 to 6, wherein the chain ester compound comprises dimethyl carbonate.

[0108] 8. The battery cell according to any one of aspects 1 to 7, wherein when the mass ratio of the lithium nickel cobalt manganese oxide material in the positive electrode film layer is ≥10%, the nonaqueous electrolyte further comprises Component A, and the Component A comprises one or more of vinyl sulfonate and 1,3-propane sultone.

[0109] 9. The battery cell according to aspect 8, wherein the mass content of the Component A in the nonaqueous electrolyte is 0.5%-4%.

[0110] 10. The battery cell according to aspect 8 or 9, wherein the mass ratio of the 1,3-propane sultone to the vinyl sulfonate is greater than 0 and less than 1.

[0111] 11. The battery cell according to any one of aspects 1 to 10, wherein when the mass ratio of the lithium nickel cobalt manganese oxide material in the positive electrode film layer is >20%, the nonaqueous electrolyte further comprises Component B, and the Component B comprises one or more of lithium hexafluorophosphate and lithium bisfluorosulfonimide.

[0112] 12. The battery cell according to aspect 11, wherein the molar concentration of the Component B in the nonaqueous electrolyte is 0.9-1.2 M.

[0113] 13. The battery cell according to aspect 11 or 12, wherein the mass content of the Component B in the nonaqueous electrolyte is 12%-16%.

[0114] 14. The battery cell according to any one of aspects 11 to 13, wherein the molar ratio of the lithium hexafluorophosphate to the lithium bisfluorosulfonimide is 1.5:1-5:1.

[0115] 15. The battery cell according to any one of aspects 1 to 14, wherein the nonaqueous electrolyte further comprises vinyl carbonate, and the mass content of the vinyl carbonate in the nonaqueous electrolyte is greater than 0 and less than or equal to 40%.

[0116] 16. The battery cell according to any one of aspects 1 to 15, wherein the mass percentage of the lithium manganese iron phosphate material in the positive electrode film layer is 50% to 90%, the mass percentage of Fe element in the positive electrode film layer is 16% to 32%, and the mass percentage of Ni element in the positive electrode film layer is 5.1% to 25%; and the mass content of the vinylene carbonate in the non-aqueous electrolyte is 1% to 1.5%.

[0117] 17. The battery cell according to any one of aspects 1 to 16, wherein the mass percentage of the lithium manganese iron phosphate material in the positive electrode film layer is 60% to 80%, the mass percentage of Fe element in the positive electrode film layer is 21% to 28%, and the mass percentage of Ni element in the positive electrode film layer is 9% to 20%; and the molar percentage of Ni element in the total of Ni, Co, and Mn elements in the lithium nickel cobalt manganese oxide is 0.7 to 0.95.

[0118] 18. The battery cell according to any one of aspects 1 to 17, wherein the lithium manganese iron phosphate material further comprises one or more elements selected from the group consisting of Al, B, Ca, Cr, K, Mg, Ni, Co, Na, Si, Ti, V, Cu, Zn, S, Sc, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, Cl, C, N, F.

[0119] 19. The battery cell according to aspect 18, comprising one or more of the following:

[0120] the mass percentage of Al element in the lithium manganese iron phosphate material is 0.01% to 0.03%;

[0121] the mass percentage of Ca element in the lithium manganese iron phosphate material is 0.005% to 0.02%;

[0122] the mass percentage of Cr element in the lithium manganese iron phosphate material is 0.0018% to 0.004%;

[0123] the mass percentage of Cu element in the lithium manganese iron phosphate material is 0.00275% to 0.006%;

[0124] the mass percentage of Fe element in the lithium manganese iron phosphate material is 6.955% to 14%;

[0125] the mass percentage of K element in the lithium manganese iron phosphate material is 0.00045% to 0.001%;

[0126] the mass percentage of Li element in the lithium manganese iron phosphate material is 3% to 4.5%;

[0127] The mass percentage of Mg element in the lithium iron manganese phosphate material is 0.003%-0.007%;

[0128] The mass percentage of Mn element in the lithium iron manganese phosphate material is 9.86%-20%;

[0129] The mass percentage of Na element in the lithium iron manganese phosphate material is 0.016%-0.04%;

[0130] The mass percentage of P element in the lithium iron manganese phosphate material is 9.65%-20%;

[0131] The mass percentage of Si element in the lithium iron manganese phosphate material is 0.00125%-0.003%;

[0132] The mass percentage of Ti element in the lithium iron manganese phosphate material is 0.023%-0.05%;

[0133] The mass percentage of V element in the lithium iron manganese phosphate material is 0.0845%-0.18%;

[0134] The mass percentage of Zn element in the lithium iron manganese phosphate material is 0.00115%-0.003%.

[0135] 20. The battery cell according to any one of aspects 1-19, wherein the lithium nickel cobalt manganese oxide material further comprises one or more of Al, B, Fe, Sr, Ti, Y, Zr, Na, K, Mg, Si, P, S, Ca, Sc, V, Cr, Cu, Zn, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, F.

[0136] 21. The battery cell according to aspect 20, comprising one or more of:

[0137] The mass percentage of Al element in the lithium nickel cobalt manganese oxide material is 0.0315%-0.07%;

[0138] The mass percentage of B element in the lithium nickel cobalt manganese oxide material is 0.00195%-0.005%;

[0139] The mass percentage of Co element in the lithium nickel cobalt manganese oxide material is 3.825%-8%;

[0140] The mass percentage of Fe element in the lithium nickel cobalt manganese oxide material is 0.0016%-0.004%;

[0141] The mass percentage of Li element in the lithium nickel cobalt manganese oxide material is 5.5%-6.8%;

[0142] The mass percentage of Mn in the nickel-cobalt-manganese lithium material is 1.22%-2.8%;

[0143] The mass percentage of Ni in the nickel-cobalt-manganese lithium material is 24.93%-51%;

[0144] The mass percentage of Sr in the nickel-cobalt-manganese lithium material is 0.00005%-0.0002%;

[0145] The mass percentage of Ti in the nickel-cobalt-manganese lithium material is 0.00015%-0.0004%;

[0146] The mass percentage of Y in the nickel-cobalt-manganese lithium material is 0.0004%-0.0009%;

[0147] The mass percentage of Zr in the nickel-cobalt-manganese lithium material is 0.128%-0.3%.

[0148] 22. The battery cell according to any one of aspects 1-21, wherein the nickel-cobalt-manganese lithium material comprises spheroid-like particles, and the lithium-iron-manganese phosphate material comprises particles with a shape suitable for filling the gaps between the spheroid-like particles.

[0149] 23. The battery cell according to any one of aspects 1-22, wherein the nickel-cobalt-manganese lithium material comprises particles with a longest diameter of 4-8 pm, and the lithium-iron-manganese phosphate material comprises particles with a shortest diameter of 0.1-0.3 pm.

[0150] 24. The battery cell according to any one of aspects 1-23, wherein the nickel-cobalt-manganese lithium material comprises particles with a shortest diameter of 0.5-2 pm, and the lithium-iron-manganese phosphate material comprises particles with a longest diameter of 1-2 pm.

[0151] 25. The battery cell according to any one of aspects 1-24, wherein the nickel-cobalt-manganese lithium material is a polycrystalline material.

[0152] 26. The battery cell according to any one of aspects 1-25, wherein the positive electrode film layer further comprises a lithium supplement material, and the lithium supplement material comprises one or more of lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganite, lithium tartrate, and trilithium citrate.

[0153] 27. The battery cell according to any one of aspects 1-26, wherein the negative electrode film layer comprises a negative electrode active material, and the negative electrode active material comprises graphite and a silicon material, and the mass percentage of silicon in the negative electrode film layer is 0.3%-10%.

[0154] 28. The battery cell according to aspect 27, wherein the silicon material comprises one or more of silicon oxide and silicon-carbon composite.

[0155] 29. The battery cell of any one of aspects 27 or 28, wherein the silicon material comprises a silicon-carbon composite, and the silicon element has a mass fraction of 1-5% in the negative electrode film layer.

[0156] 30. The battery cell of any one of aspects 1-29, wherein the positive electrode film layer has an area density of 0.32-0.36 mg / 15 40.25 mm 2 .

[0157] 31. The battery cell of any one of aspects 1-30, wherein the negative electrode film layer has an area density of 0.169-0.190 mg / 15 40.25 mm 2 .

[0158] 32. The battery cell of any one of aspects 1-31, wherein the positive electrode tab has a height that is > 93% of the height of the electrode assembly.

[0159] 33. The battery cell of any one of aspects 1-32, wherein the positive electrode tab has a length that is > 92% of the length of the electrode assembly.

[0160] 34. The battery cell of any one of aspects 1-33, wherein the battery full discharge state is a state reached by discharging at 0.33 C to 2.0 V, and then discharging at 0.05 C to 2.0 V at 25 °C; and wherein, in the battery full discharge state, the thickness ratio of the positive electrode film layer to the positive electrode current collector is > 10 or 12-14.

[0161] 35. The battery cell of any one of aspects 1-34, wherein the battery full discharge state is a state reached by discharging at 0.33 C to 2.0 V, and then discharging at 0.05 C to 2.0 V at 25 °C; and wherein, in the battery full discharge state, the positive electrode film layer has a green density of 2.85-2.95 g / cm 3 .

[0162] 36. The battery cell of any one of aspects 1-35, wherein the battery full discharge state is a state reached by discharging at 0.33 C to 2.0 V, and then discharging at 0.05 C to 2.0 V at 25 °C; and wherein, in the battery full discharge state, the thickness ratio of the negative electrode film layer to the negative electrode current collector is > 30 or 33-35.

[0163] 37. The battery cell of any one of aspects 1-36, wherein the battery full discharge state is a state reached by discharging at 0.33 C to 2.0 V, and then discharging at 0.05 C to 2.0 V at 25 °C; and wherein, in the battery full discharge state, the negative electrode film layer has a green density of 1.4-1.5 g / cm 3 .

[0164] 38. The battery cell of any one of aspects 1 to 37, the negative electrode film layer comprises a first negative electrode film layer on the negative electrode current collector and a second negative electrode film layer on the first negative electrode film layer, the first negative electrode film layer and the second negative electrode film layer comprise graphite.

[0165] 39. The battery cell of any one of aspects 1 to 38, the positive electrode current collector has a thickness of < 15 pm or 10-13 pm.

[0166] 40. The battery cell of any one of aspects 1 to 39, the negative electrode current collector has a thickness of < 6 pm or 4-5.5 pm.

[0167] 41. The battery cell of any one of aspects 1 to 40, the battery cell further comprises tabs, the tabs are arranged along a height direction of the positive electrode tab, a ratio of a total height of the tabs to the height of the positive electrode tab is > 50%.

[0168] 42. The battery cell of any one of aspects 1 to 41, the battery cell further comprises a tab post, the tab post is two.

[0169] 43. The battery cell of any one of aspects 1 to 42, the battery cell further comprises tabs and a tab post, the tabs are directly connected to the tab post.

[0170] 44. The battery cell of any one of aspects 1 to 43, the battery cell further comprises a housing, the housing is made of aluminum, the housing has a wall thickness of 0.2-0.3 mm.

[0171] 45. The battery cell of any one of aspects 1 to 44, a ratio of a length to a height of the electrode assembly is 4-7.

[0172] 46. The battery cell of any one of aspects 1 to 45, the electrode assembly has a length of 400-600 mm.

[0173] 47. The battery cell of any one of aspects 1 to 46, the electrode assembly has a height of 90-120 mm.

[0174] 48. The battery cell of any one of aspects 1 to 47, the electrode assembly has a thickness of 13-25 pm.

[0175] 49. The battery cell of any one of aspects 1 to 48, the battery cell has a discharge plateau voltage from 4.25 V to 2.0 V at 1 / 3 C of 3.574-3.63 V or 3.595-3.63 V.

[0176] 50. The battery cell of any one of aspects 1 to 49, the battery cell has an energy density of 210-250 Wh / kg.

[0177] 51. The battery cell according to any one of aspects 1 to 50, wherein the upper limit voltage of the battery cell at room temperature is 4.2-4.3 V.

[0178] 52. A battery device comprising the battery cell according to any one of aspects 1 to 51; the battery device comprises a battery module, a battery pack, or an energy storage device.

[0179] 53. A power consuming device comprising the battery cell according to any one of aspects 1 to 51 or the battery device according to aspect 52.

[0180] 54. The power consuming device according to aspect 53, wherein the power consuming device is a vehicle, and the length direction of the battery cell or the battery device is parallel to the running direction of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0181] Fig. 1 is a schematic view of a positive or negative electrode sheet structure according to an embodiment of the present application.

[0182] Fig. 2 is a schematic view of a positive or negative electrode sheet structure according to another embodiment of the present application.

[0183] Fig. 3 is a schematic view of a positive or negative electrode sheet structure according to another embodiment of the present application.

[0184] Fig. 4 is a schematic view of a battery cell and a pole structure according to an embodiment of the present application.

[0185] Fig. 5 is a schematic view of an electrode assembly according to an embodiment of the present application.

[0186] Fig. 6 is an exploded view of a battery cell according to an embodiment of the present application.

[0187] Fig. 7 is a schematic view of a battery pack according to an embodiment of the present application.

[0188] Fig. 8 is an exploded view of the battery pack according to an embodiment of the present application shown in Fig. 7.

[0189] Fig. 9 is a schematic view of a power consuming device using the battery pack according to an embodiment of the present application as a power source.

[0190] REFERENCE NUMERALS: 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 battery cell; 51 case; 52 electrode assembly; 53 top cover assembly; 61 tab portion; 62 main body portion; 63 positive pole; 64 negative pole. DETAILED DESCRIPTION

[0191] Hereinafter, specific embodiments of the battery cell, the battery module, the battery pack, and the electric device of the present application will be described in detail with appropriate reference to the accompanying drawings. However, there will be cases where unnecessary detailed description is omitted. For example, there will be cases where detailed description of matters known to those skilled in the art, repeated description of substantially identical configurations, is omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to sufficiently understand the present application, and are not intended to limit the subject matter recited in the claims.

[0192] The ranges disclosed herein are defined by their lower and upper limits. Ranges that include both a lower limit and an upper limit are defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the range. Ranges that include only one of a lower or an upper limit are also defined by a lower or an upper limit. Ranges that include only one of a lower or an upper limit are also defined to have a value of 0 as the unselected limit. For example, a range of 60-120 and a range of 80-110 are understood to be a range of 60-110 and a range of 80-120, respectively. Furthermore, if a minimum range value of 1 and 2 is listed, and if a maximum range value of 3, 4, and 5 is listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present application, unless otherwise stated, a numerical range "a-b" indicates a shorthand manner of describing each and every number that is contained in the range, wherein a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers that are contained in the range of "0-5" have been listed herein, and "0-5" is merely a shorthand manner of describing each and every number that is contained in the range. Additionally, when a parameter is stated to be an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and the like.

[0193] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0194] Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0195] Unless otherwise specified, all steps of the present application can be performed in sequence or randomly, and preferably in sequence. For example, a method includes steps (a) and (b), which means that the method can include steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, it is mentioned that the method can further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or steps (a), (c), and (b), or steps (c), (a), and (b), etc.

[0196] [battery cell]

[0197] Battery cell, also known as rechargeable battery or storage battery, refers to a battery that can continue to be used by activating active materials through charging after the battery is discharged.

[0198] Generally, a battery cell includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During the charging and discharging process of the battery, active ions (such as lithium ions) are inserted and extracted between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent short circuit between the positive and negative electrodes, and at the same time to allow the active ions to pass through. The electrolyte is between the positive electrode sheet and the negative electrode sheet, mainly to conduct the active ions.

[0199] One embodiment of the present application provides a battery cell, comprising an electrode assembly and a non-aqueous electrolyte, the electrode assembly comprising a positive electrode sheet and a negative electrode sheet; the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer located on at least one side of the positive electrode current collector, and the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer located on at least one side of the negative electrode current collector; wherein,

[0200] The positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises a lithium manganese iron phosphate material and a lithium nickel cobalt manganese oxide material; in the lithium nickel cobalt manganese oxide material, the molar proportion of Ni element in the total of Ni, Co and Mn elements is 0.5-0.95, for example, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.83, 0.85, 0.9, 0.95 or a range consisting of any of the above values;

[0201] The non-aqueous electrolyte comprises vinylene carbonate, and the mass content of the vinylene carbonate in the non-aqueous electrolyte is 0.5%-2%, for example, 0.5%, 0.8%, 1%, 1.5%, 1.8%, 2% or a range consisting of any of the above values;

[0202] The non-aqueous electrolyte comprises at least one of linear carbonate and linear carboxylate, and the conductivity of the non-aqueous electrolyte is 9-14 mS / cm, for example, 9 mS / cm, 9.5 mS / cm, 10 mS / cm, 10.5 mS / cm, 11 mS / cm, 11.5 mS / cm, 12 mS / cm, 12.5 mS / cm, 13 mS / cm, 13.5 mS / cm, 14 mS / cm or a range consisting of any of the above values.

[0203] The lithium nickel cobalt manganese oxide material and the lithium manganese iron phosphate material are mixed to have the advantages of low cost and high energy density, thereby making up for the lack of energy density range between single lithium manganese iron phosphate battery and single lithium nickel cobalt manganese oxide battery. However, the surface residual alkali content of the lithium nickel cobalt manganese oxide material with high nickel content is high, which is easy to react with the acid in the electrolyte to generate water. The water can accelerate the generation of acid in the electrolyte, and the generated acid can easily destroy the structure of the positive electrode material, leading to the dissolution of transition metal ions. The dissolved transition metal ions are easy to accumulate on the surface of the negative electrode SEI film, catalyze the damage of the SEI film, and cause the cycle performance of the battery to decrease. Moreover, the rate performance of the lithium manganese iron phosphate material is not as good as that of the lithium nickel cobalt manganese oxide material, so mixing the lithium manganese iron phosphate material into the positive electrode active material causes the rate performance of the battery to decrease.

[0204] Further, by including a certain amount of vinylene carbonate in the non-aqueous electrolyte, it is beneficial to form stable components on the surface of the negative electrode to improve the stability of the negative electrode SEI film, slow down the problem of the destruction of the SEI film caused by the use of the lithium nickel cobalt manganese oxide material with high nickel content, and the appropriate amount of vinylene carbonate can also reduce the impedance of the SEI film and improve the power performance lost due to the use of the lithium manganese iron phosphate material with low power. At the same time, the electrical conductivity of the electrolyte is within a certain range, which reduces the transmission resistance of lithium ions in the liquid phase, is beneficial to make up for the power loss caused by the increase of the SEI film impedance, is also beneficial to make up for the power loss caused by the mixing of the lithium manganese iron phosphate material, and is also beneficial to reduce the negative impact of too high electrical conductivity on high-temperature cycle performance. In this way, the battery has high energy density, and the cycle performance and power performance of the battery are improved.

[0205] In the present application, the molar proportion of the Ni element in the lithium nickel cobalt manganese oxide material in the total of Ni, Co and Mn elements can be tested by conventional methods in the art. For example, the battery monomer is disassembled into a positive electrode sheet, the positive electrode sheet is washed with DMC (dimethyl carbonate) and dried, and the positive electrode sheet is cut off. Since the morphology of the lithium manganese iron phosphate material is different from that of the lithium nickel cobalt manganese oxide material, a plurality of (for example, 10-50) lithium nickel cobalt manganese oxide particles on the cross section of the positive electrode sheet are tested by SEM-EDS combined instrument, and the average value is obtained to obtain the mass ratio of Ni, Co and Mn elements in the lithium nickel cobalt manganese oxide material, and then the molar proportion of the Ni element in the lithium nickel cobalt manganese oxide material in the total of Ni, Co and Mn elements is calculated.

[0206] In the present application, the electrical conductivity of the non-aqueous electrolyte is tested by conventional methods in the art. For example, a conductivity meter is used for testing.

[0207] In some embodiments, the non-aqueous electrolyte comprises a linear carbonate, the linear carbonate comprises dimethyl carbonate, and the mass content of the dimethyl carbonate in the non-aqueous electrolyte is 4-20% or 8-16%, for example, 4%, 5%, 6%, 8%, 9%, 10%, 11%, 12%, 14%, 16%, 17%, 18%, 20%, or a range consisting of any of the above values. In this way, the conductivity of the electrolyte is adjusted by a certain amount of dimethyl carbonate, which is conducive to improving the power performance of the battery while ensuring the high-temperature cycle performance of the battery.

[0208] In some embodiments, the non-aqueous electrolyte comprises a linear carboxylic acid ester, and the mass content of the linear carboxylic acid ester in the non-aqueous electrolyte is 5-25%, for example, 5%, 8%, 10%, 12%, 15%, 16%, 18%, 20%, 22%, 23%, 25%, or a range consisting of any of the above values.

[0209] In some embodiments, the linear carboxylic acid ester comprises at least one of methyl formate, methyl acetate, ethyl formate, and ethyl acetate.

[0210] In this way, the conductivity of the electrolyte is adjusted by a certain amount of linear carboxylic acid ester, which is conducive to improving the power performance of the battery while ensuring the high-temperature cycle performance of the battery.

[0211] In some embodiments, the viscosity of the non-aqueous electrolyte at room temperature is 1-3 mPa·s or 2-3 mPa·s, for example, 1 mPa·s, 1.5 mPa·s, 1.8 mPa·s, 2 mPa·s, 2.2 mPa·s, 2.3 mPa·s, 2.5 mPa·s, 2.7 mPa·s, 2.8 mPa·s, 3 mPa·s, or a range consisting of any of the above values.

[0212] In this application, the viscosity of the non-aqueous electrolyte can be tested by conventional methods in the art. For example, a rotary viscometer is used for testing. When the rotor (for example, a No. 18 rotor) is rotated at a certain speed (for example, 70 rpm) in the sample at room temperature (for example, which can be selected as 20-35°C) for a certain time, the shear force received by the spring produces a torque, and the torque is proportional to the viscosity, thereby obtaining the viscosity value of the sample. For example, under the condition of ambient humidity < 80%, the sample is kept at 25°C for at least 30 min, the No. 18 rotor is loaded into the sample cup, the rotation speed of 70 rpm is selected, the reading is taken after 5 min rotation, and the viscosity value is obtained. More than 10 data points can be collected during testing, and the average value is taken. The testing instrument can be a Brookfield DV-2TLV viscometer.

[0213] In some embodiments, when the mass percentage of the lithium nickel cobalt manganese oxide material in the positive electrode active material is ≥10%, the non-aqueous electrolyte further comprises a sulfur-oxygen bond-containing substance, and the sulfur-oxygen bond-containing substance comprises at least one of vinyl sulfate and 1,3-propane sultone.

[0214] In some embodiments, the mass content of the sulfur-oxygen bond-containing substance in the non-aqueous electrolyte is 0.5%-4% or 0.5%-2%, for example, 0.5%, 1%, 1.5%, 2%, 2.2%, 2.3%, 2.5%, 2.7%, 2.8%, 3%, 3.5%, 4%, or a range consisting of any of the foregoing values.

[0215] Therefore, when the mass percentage of the lithium nickel cobalt manganese oxide material in the positive electrode active material is ≥10%, in order to take advantage of the capacity of the lithium nickel cobalt manganese oxide material, the upper limit voltage of the battery is based on the lithium nickel cobalt manganese oxide material, the sulfur-oxygen bond-containing substance is formed on the positive electrode under high voltage, the positive electrode interfacial film component is optimized, the side reaction between the surface residual alkali of the lithium nickel cobalt manganese oxide material and the acidic substance in the electrolyte is inhibited, and the battery cycle performance is improved.

[0216] In some embodiments, the mass ratio of the 1,3-propane sultone to the vinyl sulfate in the non-aqueous electrolyte is greater than 0 and less than 1.

[0217] Therefore, the mass of the vinyl sulfate is greater than the mass of the 1,3-propane sultone, which can reduce the impedance of the positive electrode interfacial film and improve the power performance of the battery.

[0218] In this application, the mass content of the vinyl sulfate and the 1,3-propane sultone in the non-aqueous electrolyte is tested by a conventional method in the art. For example, gas chromatography is used for testing.

[0219] In some embodiments, the non-aqueous electrolyte further comprises a lithium salt, and the mass content of the lithium salt in the non-aqueous electrolyte is 12%-16%, for example, 12%, 13%, 14%, 15%, 16%, or a range consisting of any of the foregoing values.

[0220] In some embodiments, when the mass percentage of the lithium nickel cobalt manganese oxide material in the positive electrode active material is ≥20%, the lithium salt comprises lithium hexafluorophosphate and a lithium fluorosulfonamide salt, and the lithium fluorosulfonamide salt comprises at least one of lithium monofluorosulfonimide, lithium bifluorosulfonimide, and lithium trifluorosulfonimide.

[0221] Therefore, the lithium hexafluorophosphate and the lithium fluorosulfonamide salt in the non-aqueous electrolyte can improve the heat resistance temperature of the electrolyte, thereby reducing the risk of positive electrode thermal runaway caused by the heat resistance of the electrolyte.

[0222] In some embodiments, the lithium salt comprises lithium hexafluorophosphate and lithium bisfluorosulfonylimide, and the mass ratio of the lithium hexafluorophosphate to the lithium bisfluorosulfonylimide is 1.23:1-4.28:1, for example, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, 2.7:1, 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.1:1, 4.2:1, 4.28:1, or a range derived from any of the above values.

[0223] In this way, the ratio of lithium hexafluorophosphate to lithium bisfluorosulfonylimide within the above range can reduce the risk of positive electrode thermal runaway caused by electrolyte heat intolerance on the one hand, and reduce the negative impact of lithium bisfluorosulfonylimide on the safety performance of the negative electrode on the other hand, thereby improving the safety performance of the battery.

[0224] In this application, the mass content of lithium hexafluorophosphate and lithium bisfluorosulfonylimide in the non-aqueous electrolyte is tested by conventional methods in the art.

[0225] In some embodiments, the non-aqueous electrolyte further comprises ethylene carbonate, and the mass content of the ethylene carbonate in the non-aqueous electrolyte is 12%-35%, for example, 12%, 15%, 18%, 20%, 22%, 25%, 27%, 30%, 32%, 33%, 34%, 35%, or a range derived from any of the above values.

[0226] In this way, on the one hand, the inclusion of ethylene carbonate in the non-aqueous electrolyte is conducive to reducing the impedance of the interfacial film, while ensuring the cycle performance of the battery, and improving the power performance of the battery; on the other hand, the above content can inhibit the side reaction of ethylene carbonate with the positive active material, thereby improving the cycle performance and safety performance of the battery.

[0227] In the embodiments of the present application, the types and contents of organic components in the electrolyte are the meanings known in the art, and can be detected by using devices and methods known in the art, for example, the composition of the electrolyte can be measured by liquid chromatography, gas chromatography, ion chromatography, liquid nuclear magnetic resonance method, etc. For example, the organic components in the electrolyte can be qualitatively and quantitatively analyzed by gas chromatography according to GB / T 9722-2006 "General Gas Chromatography for Chemical Reagents".

[0228] The test sample in the embodiments of the present application can be a freshly prepared electrolyte as a sample, or the free electrolyte obtained from a battery after the battery is discharged (discharged to the lower limit cutoff voltage so that the charged state of the battery is about 0% SOC).

[0229] In the present application, the mass content of linear carbonate, vinylene carbonate, vinyl sulfate, 1,3-propanesulfonic acid lactone, ethylene carbonate, linear carboxylate in the non-aqueous electrolyte can be tested by conventional methods in the art. For example, gas chromatography is used. The specific operating conditions of gas chromatography can exemplarily include: the main components of the gas chromatography column include fused silica, stationary phase (phenylmethyl polysiloxane, polyethylene glycol, alumina or molecular sieve), protective layer (polyimide coating); the injection port temperature is 300°C; the column temperature is 250°C; the detector is 300°C; the carrier flow rate is 1.5 mL / min.

[0230] In the embodiments of the present application, the type and content of the inorganic component / lithium salt concentration in the electrolyte are the meanings known in the art, which can be detected by using the devices and methods known in the art, for example, the qualitative or quantitative analysis of the inorganic component / lithium salt concentration in the electrolyte can be performed by ion chromatography according to the standard JY / T020-1996 "General Ion Chromatography Analysis Method". In the embodiments of the present application, the freshly prepared electrolyte can be taken as a sample, or the free electrolyte obtained from the battery after the battery is discharged (discharged to the lower limit cutoff voltage so that the charged state of the battery is about 0% SOC), and the ion chromatography analysis method is used for detection.

[0231] In some embodiments, the mass percentage of Ni element in the positive electrode film layer is 5.1%-25% (for example, 5.1%, 7%, 9%, 10%, 12%, 14%, 15%, 17%, 19%, 20%, 22%, 24%, 25% or a range consisting of any of the above values), the mass percentage of Fe element in the positive electrode film layer is 6%-15% (for example, 6%, 7%, 8%, 9%, 10%, 12%, 13%, 14%, 15% or a range consisting of any of the above values), and the mass content of the vinylene carbonate in the non-aqueous electrolyte is 1%-1.5% (for example, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5% or a range consisting of any of the above values).

[0232] In some embodiments, the mass percentage of the lithium manganese iron phosphate material in the positive electrode active material is 50%-90%, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or a range consisting of any of the above values.

[0233] Therefore, when the mass ratio of the lithium iron manganese phosphate material in the positive electrode film layer is high, the platform voltage and the energy density are improved, but the manganese ions are easily dissolved and enriched on the surface of the negative electrode SEI film, which causes the side reaction to intensify, the gas production increases, and the cycle performance of the battery is affected. By adjusting the content of vinylene carbonate in the electrolyte within the above range, the stability of the components of the negative electrode SEI film is improved, thereby improving the cycle performance of the battery.

[0234] In some embodiments, the mass ratio of the lithium iron manganese phosphate material in the positive electrode active material is 50%-90%, and correspondingly, the molar ratio of manganese to iron in the lithium iron manganese phosphate material is 6:4-7:3.

[0235] In some embodiments, the mass ratio of the lithium iron manganese phosphate material in the positive electrode active material is 60%-80% (for example, 60%, 65%, 70%, 75%, 80%, or a range composed of any of the above values); and in the lithium nickel cobalt manganese oxide material, the molar ratio of Ni element in the total of Ni, Co, and Mn elements is 0.7-0.95, for example, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, or a range composed of any of the above values.

[0236] Therefore, while maintaining the cost advantage, the battery has good energy density and cycle performance.

[0237] In this application, the mass ratio of Fe element and Ni element in the positive electrode film layer is tested by a conventional method in the art. For example, the battery monomer is disassembled, the positive electrode sheet is taken out, the positive electrode sheet is washed with DMC (dimethyl carbonate), and the positive electrode sheet is dried, the material in the positive electrode film layer is collected, and the mass ratio of each element in the positive electrode film layer is tested by ICP.

[0238] In some embodiments, the lithium iron manganese phosphate material further comprises one or more elements selected from Al, B, Ca, Cr, K, Mg, Ni, Co, Na, Si, Ti, V, Cu, Zn, S, Sc, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, Cl, C, N, F.

[0239] In some embodiments, the lithium iron manganese phosphate material comprises one or more of the following:

[0240] The mass ratio of Al element in the lithium iron manganese phosphate material is 0.01%-0.03%;

[0241] The mass ratio of Ca element in the lithium iron manganese phosphate material is 0.005%-0.02%;

[0242] The mass percentage of Cr in the lithium manganese iron phosphate material is 0.0018%-0.004%;

[0243] The mass percentage of Cu in the lithium manganese iron phosphate material is 0.00275%-0.006%;

[0244] The mass percentage of Fe in the lithium manganese iron phosphate material is 6.955%-14%;

[0245] The mass percentage of K in the lithium manganese iron phosphate material is 0.00045%-0.001%;

[0246] The mass percentage of Li in the lithium manganese iron phosphate material is 3%-4.5%;

[0247] The mass percentage of Mg in the lithium manganese iron phosphate material is 0.003%-0.007%;

[0248] The mass percentage of Mn in the lithium manganese iron phosphate material is 9.86%-20%;

[0249] The mass percentage of Na in the lithium manganese iron phosphate material is 0.016%-0.04%;

[0250] The mass percentage of P in the lithium manganese iron phosphate material is 9.65%-20%;

[0251] The mass percentage of Si in the lithium manganese iron phosphate material is 0.00125%-0.003%;

[0252] The mass percentage of Ti in the lithium manganese iron phosphate material is 0.023%-0.05%;

[0253] The mass percentage of V in the lithium manganese iron phosphate material is 0.0845%-0.18%;

[0254] The mass percentage of Zn in the lithium manganese iron phosphate material is 0.00115%-0.003%.

[0255] In some embodiments, the lithium nickel cobalt manganese oxide material further comprises one or more of Al, B, Fe, Sr, Ti, Y, Zr, Na, K, Mg, Si, P, S, Ca, Sc, V, Cr, Cu, Zn, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, F.

[0256] In some embodiments, the lithium nickel cobalt manganese oxide material comprises one or more of:

[0257] The mass percentage of Al in the nickel-cobalt-manganese lithium material is 0.0315%-0.07%;

[0258] The mass percentage of B in the nickel-cobalt-manganese lithium material is 0.00195%-0.005%;

[0259] The mass percentage of Co in the nickel-cobalt-manganese lithium material is 3.825%-8%;

[0260] The mass percentage of Fe in the nickel-cobalt-manganese lithium material is 0.0016%-0.004%;

[0261] The mass percentage of Li in the nickel-cobalt-manganese lithium material is 5.5%-6.8%;

[0262] The mass percentage of Mn in the nickel-cobalt-manganese lithium material is 1.22%-2.8%;

[0263] The mass percentage of Ni in the nickel-cobalt-manganese lithium material is 24.93%-51%;

[0264] The mass percentage of Sr in the nickel-cobalt-manganese lithium material is 0.00005%-0.0002%;

[0265] The mass percentage of Ti in the nickel-cobalt-manganese lithium material is 0.00015%-0.0004%;

[0266] The mass percentage of Y in the nickel-cobalt-manganese lithium material is 0.0004%-0.0009%;

[0267] The mass percentage of Zr in the nickel-cobalt-manganese lithium material is 0.128%-0.3%.

[0268] In some embodiments, the nickel-cobalt-manganese lithium material comprises spherical particles, and the lithium manganese iron phosphate material comprises particles with a shape suitable for filling the gaps between the spherical particles. In this way, the compaction density of the positive electrode active material is improved, thereby improving the energy density of the battery.

[0269] In some embodiments, the nickel-cobalt-manganese lithium material is a polycrystalline material. In this way, the use of a polycrystalline nickel-cobalt-manganese lithium material is conducive to improving the power of the battery. The spherical cobalt-manganese lithium material is mostly secondary particle morphology, and has good power performance.

[0270] In some embodiments, the nickel-cobalt-manganese lithium material comprises particles with a longest diameter of 4-8 μm and particles with a longest diameter of 0.5-2 μm. In this way, the combination of nickel-cobalt-manganese lithium particles with different particle sizes is conducive to improving the compaction density of the positive electrode active material and improving the energy density of the battery.

[0271] In some embodiments, the lithium manganese iron phosphate material includes particles with a longest diameter of 0.1-0.3 μm and particles with a longest diameter of 1-2 μm. In this way, the combination of lithium manganese iron phosphate particles with different particle sizes is used to improve the compaction density of the positive electrode active material and improve the energy density of the battery.

[0272] In some embodiments, the "longest diameter" refers to: cutting the positive electrode sheet including lithium-containing phosphate particles along the thickness direction of the sheet to expose the longitudinal section of the positive electrode film layer; and determining the longest diameter of the lithium-containing phosphate particles by scanning electron microscopy (SEM) testing of the longitudinal section of the positive electrode film layer. Specifically, the maximum value of the distance between any two points on the outer edge line of the particle is the "longest diameter" of the particle.

[0273] In this application, the longest diameter of the particles of the lithium manganese iron phosphate material (or lithium nickel cobalt manganese oxide material) can be tested by conventional methods in the art. For example, the battery monomer is disassembled to obtain the positive electrode sheet, the positive electrode sheet is washed with DMC (dimethyl carbonate) and dried, the positive electrode sheet is cut along the thickness direction to expose the longitudinal section of the positive electrode film layer, and the particles of the lithium manganese iron phosphate material and the lithium nickel cobalt manganese oxide material can be distinguished due to their different particle morphologies. For the lithium manganese iron phosphate particles (or lithium nickel cobalt manganese particles), SEM is used to measure multiple times from different directions of each particle, and the maximum measurement value is taken as the longest diameter and the minimum measurement value is taken as the shortest diameter. A plurality of (e.g., 10-100) particles of each material are tested.

[0274] In some embodiments, the positive electrode film layer further includes a lithium supplement material, and the lithium supplement material includes one or more of lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganate, lithium tartrate, and trilithium citrate. In this way, the energy density of the battery is improved.

[0275] In some embodiments, the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes graphite and a silicon material, and the mass fraction of silicon in the negative electrode film layer is 0.3%-10%, for example, 0.3%, 0.5%, 0.8%, 1%, 3%, 4%, 5%, 7%, 8%, 9%, 10%, or a range consisting of any of the above values. In this way, the energy density of the battery is improved.

[0276] In this application, the mass fraction of silicon in the negative electrode film layer is tested by conventional methods in the art. For example, the battery monomer is disassembled to obtain the negative electrode sheet, the negative electrode sheet is washed with DMC (dimethyl carbonate) and dried, and the material in the negative electrode film layer is collected, and ICP is used to test the mass fraction of silicon in the negative electrode film layer.

[0277] In some embodiments, the silicon material comprises one or more of silicon oxide, silicon-carbon composite.

[0278] In some embodiments, the silicon material comprises silicon-carbon composite, and the mass percentage of silicon element in the negative electrode film layer is 1-5%. This is beneficial to improve the energy density of the battery.

[0279] In some embodiments, the areal density of the positive electrode film layer is 0.32-0.36 mg / 1540.25 mm 2 , for example 0.32 mg / 1540.25 mm 2 , 0.34 mg / 1540.25 mm 2 , 0.35 mg / 1540.25 mm 2 , 0.36 mg / 1540.25 mm 2 or a range consisting of any of the above values.

[0280] In some embodiments, the areal density of the negative electrode film layer is 0.169-0.190 mg / 1540.25 mm 2 , for example 0.169 mg / 1540.25 mm 2 , 0.170 mg / 1540.25 mm 2 , 0.174 mg / 1540.25 mm 2 , 0.176 mg / 1540.25 mm 2 , 0.178 mg / 1540.25 mm 2 , 0.180 mg / 1540.25 mm 2 , 0.182 mg / 1540.25 mm 2 , 0.185 mg / 1540.25 mm 2 , 0.187 mg / 1540.25 mm 2 , 0.190 mg / 1540.25 mm 2 or a range consisting of any of the above values.

[0281] This is beneficial to improve the energy density of the battery.

[0282] In this application, the areal density of the positive electrode film layer (negative electrode film layer) is tested by conventional methods in the art. For example, a positive electrode sheet (negative electrode sheet) of a fixed area is cut and weighed, the weight of the positive current collector (negative current collector) of the same area is weighed and calculated in advance, and the average thickness of the positive electrode film layer (negative electrode film layer) on the positive electrode sheet (negative electrode sheet) is measured. The weight of the positive electrode sheet (negative electrode sheet) is subtracted from the weight of the positive current collector (negative current collector), and then divided by the fixed area to obtain the areal density of the positive electrode film layer (negative electrode film layer).

[0283] In some embodiments, the ratio of the size of the positive electrode film layer in the first direction to the size of the battery monomer in the first direction is ≥ 92%. Wherein the size of the battery monomer in the first direction does not include the size of the pole in the direction, and the tab is connected to the side of the positive electrode sheet along the first direction.

[0284] In some embodiments, the ratio of the size of the positive electrode film layer in the second direction to the size of the battery monomer in the second direction is ≥ 93%, and the second direction is perpendicular to the first direction.

[0285] Thus, it is beneficial to improve the utilization rate of the electrode assembly.

[0286] In some embodiments, the battery monomer 0% SOC state can be: the state reached by discharging at 0.33C to 2.0V and then discharging at 0.05C to 2.0V at 25°C; in the battery monomer configured as the 0% SOC state, the thickness ratio of the positive electrode film layer on any side of the positive electrode current collector to the positive electrode current collector is 5-8.

[0287] In some embodiments, the battery monomer 0% SOC state is: the state reached by discharging at 0.33C to 2.0V and then discharging at 0.05C to 2.0V at 25°C; in the battery monomer configured as the 0% SOC state, the thickness ratio of the negative electrode film layer on any side of the negative electrode current collector to the negative electrode current collector is 13-20.

[0288] Thus, the energy density and kinetic performance of the battery are simultaneously improved.

[0289] In some embodiments, the negative electrode film layer includes a first negative electrode film layer on the negative electrode current collector and a second negative electrode film layer on the first negative electrode film layer, and the first negative electrode film layer and the second negative electrode film layer include graphite. Thus, the kinetic performance of the battery is further improved.

[0290] In some embodiments, the thickness of the positive electrode current collector is 10-13 μm.

[0291] In some embodiments, the thickness of the negative electrode current collector is 4-5.5 μm.

[0292] Thus, the energy density of the battery is improved.

[0293] In some embodiments, the electrode assembly comprises at least two positive electrode sheets and at least two negative electrode sheets, the positive electrode sheets and the negative electrode sheets are arranged in a stack; as shown in FIG. 1 (a single sheet is shown in the figure), the positive electrode sheet and / or the negative electrode sheet comprises a tab portion 61 and a main body portion 62, the tab portion 61 extends from the main body portion 62 along a first direction, the ratio of the total size L1 of the joint area of the tab portion 61 and the main body portion 62 in a second direction to the size L of the main body portion 62 in the second direction is ≥ 50%, the second direction is perpendicular to the first direction.

[0294] In some embodiments, as shown in FIG. 2 (a single sheet is shown in the figure), the positive electrode sheet and / or the negative electrode sheet comprises a main body portion 62 and a plurality of tab portions 61, the plurality of tab portions 61 extend from the main body portion 62 along a first direction, the sizes of the joint areas of the plurality of tab portions 61 and the main body portion 62 in a second direction are L1a and L1b respectively, L1a and L1b add up to the total size L1, the ratio of L1 to the size L of the main body portion 62 in the second direction is ≥ 50%, the second direction is perpendicular to the first direction.

[0295] In some embodiments, as shown in FIG. 3 (a single sheet is shown in the figure), the positive electrode sheet and / or the negative electrode sheet comprises a main body portion 62 and a tab portion 61, the tab portion 61 extends from the main body portion 62 along a first direction, the tab portion 61 is trapezoidal, the ratio of the total size L1 of the joint area of the tab portion 61 and the main body portion 62 in a second direction to the size L of the main body portion 62 in the second direction is ≥ 50%, the second direction is perpendicular to the first direction.

[0296] In some embodiments, the battery cell comprises at least two poles of the same polarity, the poles are directly electrically connected with the tab portion of the corresponding polarity.

[0297] In some embodiments, as shown in FIG. 4, the battery cell 5 comprises two positive poles 63 and two negative poles 64, the two positive poles 63 are respectively arranged on the two sides of the battery cell 5 perpendicular to the first direction, the two negative poles 64 are respectively arranged on the two sides of the battery cell 5 perpendicular to the first direction, and the positive poles 63 and the negative poles 64 are oppositely arranged along the first direction.

[0298] In this way, the direct current impedance of the battery is reduced, the overcurrent area of the battery is increased, and the fast charging performance of the battery is improved.

[0299] In some embodiments, the size of the electrode assembly in the first direction is 400-1000 mm.

[0300] In some embodiments, the electrode assembly has a dimension in a second direction of 90-120 mm, the second direction being perpendicular to the first direction.

[0301] In some embodiments, the electrode assembly has a dimension in a third direction of 13-25 μm, the third direction being perpendicular to both the first direction and the second direction.

[0302] Thus, the energy density of the battery is improved while ensuring the fast charging performance of the battery.

[0303] In some embodiments, the platform voltage of the battery cell discharged from 4.25 V to 2.0 V at 1 / 3 C is 3.574-3.63 V or 3.595-3.63 V.

[0304] Thus, the platform voltage of the battery is improved, and the energy density of the battery is improved.

[0305] When the mass ratio of lithium manganese iron phosphate in the positive electrode film layer is 50%-90%, the platform voltage of the battery cell discharged from 4.25 V to 2.0 V at 1 / 3 C can be 3.574-3.63 V.

[0306] When the mass ratio of lithium manganese iron phosphate in the positive electrode film layer is 60%-80%, the platform voltage of the battery cell discharged from 4.25 V to 2.0 V at 1 / 3 C can be 3.595-3.63 V.

[0307] In this application, the test method of the platform voltage is as follows: the battery cell is charged to 4.25 V at a certain current (for example, 1 / 3 C), and then discharged from 4.25 V to 2.0 V at 1 / 3 C, and the platform voltage value is obtained according to the discharge curve.

[0308] In some embodiments, the energy density of the battery cell is 210-250 Wh / kg.

[0309] In this application, the energy density of the battery cell is tested as follows: the battery cell is charged to the charging cut-off voltage at a certain current, and then charged at a constant voltage of ≤0.05 C, and then discharged to the discharge cut-off voltage at a certain current, and the discharge capacity A0 and the platform voltage V are recorded; the mass of the battery cell (generally, the battery cell with the shell is weighed) M0 is weighed; the energy density of the battery cell is (A0 x V) / M0, and the unit can be Wh / kg.

[0310] In some embodiments, the upper limit charging voltage of the battery cell at room temperature is 4.2-4.3 V. Thus, the energy density of the battery is improved.

[0311] [Positive electrode sheet]

[0312] The battery will be accompanied by Li de-intercalation and consumption during charging and discharging process, and the molar content of Li is different when the battery is discharged to different states. In the enumeration of the positive electrode material in this application, the molar content of Li is the initial state of the material, that is, the state before feeding. After the positive electrode material is applied to the battery system and undergoes charging and discharging cycles, the molar content of Li will change.

[0313] In the enumeration of the positive electrode material in this application, the molar content of O is only the theoretical state value. The release of oxygen from the crystal lattice will cause the molar content of oxygen to change, and the actual molar content of O will appear to be floating.

[0314] As an example, the positive electrode current collector has two opposite surfaces in the thickness direction of itself, and the positive electrode film layer is arranged on any one or both of the two opposite surfaces of the positive electrode current collector.

[0315] In some embodiments, the positive electrode current collector can adopt a metal foil or a composite current collector. For example, as a metal foil, an aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0316] In some embodiments, the positive electrode active material can also use the positive electrode active material for batteries known in the art. These positive electrode active materials can be used only one kind alone, or two or more can be used in combination. Among them, examples can include but are not limited to at least one of lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and modified compounds thereof, lithium manganese phosphate (such as LiMnPO4), and a composite material of lithium manganese phosphate and carbon.

[0317] In some embodiments, the positive electrode film layer can also optionally include a binder. As an example, the binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic ester resin.

[0318] In some embodiments, the positive electrode film layer can further optionally include a conductive agent. As an example, the conductive agent can include at least one of super-P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0319] In some embodiments, the positive electrode tab can be prepared by dispersing the above-mentioned components for preparing the positive electrode tab, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on a positive electrode current collector; and drying, cold-pressing, or the like, to obtain the positive electrode tab.

[0320] [Negative electrode tab]

[0321] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two surfaces of the negative electrode current collector.

[0322] In some embodiments, the negative electrode current collector can employ a metal foil or a composite current collector. As a metal foil, for example, a copper foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base layer (e.g., a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0323] In some embodiments, the negative electrode active material can also employ a negative electrode active material for a battery known in the art. As an example, the negative electrode active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can be selected from at least one of elemental tin, a tin oxide compound, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative electrode active material for a battery can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0324] In some embodiments, the negative electrode film layer can further optionally include a binder. As an example, the binder can 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).

[0325] In some embodiments, the negative electrode film layer can also optionally include a conductive agent. As an example, the conductive agent can be selected from at least one of super-P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0326] In some embodiments, the negative electrode film layer can also optionally include other additives, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)), etc.

[0327] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry on a negative electrode current collector, and after processes such as drying, cold pressing, etc., the negative electrode sheet can be obtained.

[0328] [Electrolyte]

[0329] The electrolyte functions to conduct ions between the positive electrode sheet and the negative electrode sheet. The type of electrolyte is not specifically limited in the present application and can be selected as needed. For example, the electrolyte can be liquid, gel, or all-solid.

[0330] In some embodiments, the electrolyte is liquid and includes an electrolyte salt and a solvent.

[0331] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro oxalate borate, lithium di-oxalate borate, lithium difluoro di-oxalate phosphate, and lithium tetrafluoro oxalate phosphate.

[0332] In some embodiments, the solvent can be selected from at least one of vinylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoro-vinylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclobutane sulfone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0333] In some embodiments, the electrolyte can also optionally include an additive. As an example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can also include an additive capable of improving certain properties of the battery, such as an additive for improving overcharge performance of the battery, an additive for improving high-temperature or low-temperature performance of the battery, etc.

[0334] [Separator]

[0335] In some embodiments, a separator film is further included in the battery cell. The type of the separator film is not particularly limited in the present application, and any known porous separator film having good chemical stability and mechanical stability can be used.

[0336] In some embodiments, the material of the separator film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator film is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0337] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator film can be used to form an electrode assembly through a winding process or a stacking process.

[0338] In some embodiments, the battery cell can include an outer package. The outer package can be used to encapsulate the electrode assembly and the electrolyte described above.

[0339] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, or the like. The outer package of the battery cell can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, and as the plastic, polypropylene, polybutylene terephthalate, polybutylene succinate, or the like can be listed.

[0340] The shape of the battery cell is not particularly limited in the present application, and the battery cell can be cylindrical, square, or any other shape. For example, FIG. 5 is an electrode assembly 52 of a battery cell in a square structure as an example.

[0341] In some embodiments, referring to FIG. 6, the outer package can include a shell 51 and a cover plate 53. The shell 51 can 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 communicating with the receiving cavity, and the cover plate 53 can be arranged on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator film can be used to form an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. The number of the electrode assemblies 52 included in the battery cell 5 can be one or more, and a person skilled in the art can select according to the specific actual needs.

[0342] In some embodiments, the battery cell can be assembled into a battery module, and the number of the battery cells included in the battery module can be one or more, and a person skilled in the art can select according to the application and capacity of the battery module.

[0343] In the battery module, the plurality of battery cells can be arranged in sequence along the length direction of the battery module. Of course, other arrangements can also be used. The plurality of battery cells can be fixed by fasteners.

[0344] Optionally, the battery module can further include a housing having an accommodation space, and the plurality of battery cells are accommodated in the accommodation space.

[0345] In some embodiments, the battery module described above can be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0346] FIGS. 7 and 8 are a battery pack 1 as an example. Referring to FIGS. 7 and 8, the battery pack 1 can include a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be arranged on the lower box body 3 to form an enclosed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0347] In addition, the present application also provides a power utilization device, which includes at least one of the battery cell, the battery module, or the battery pack provided by the present application. The battery cell, the battery module, or the battery pack can be used as a power supply of the power utilization device, or can be used as an energy storage unit of the power utilization device. The power utilization device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0348] As the power utilization device, the battery cell, the battery module, or the battery pack can be selected according to the use requirements thereof.

[0349] FIG. 9 is a power utilization device as an example. The power utilization device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the battery cell for the power utilization device, the battery pack or the battery module can be used.

[0350] Example 1

[0351] (1) Positive electrode tab: the positive electrode film layer includes positive electrode active material lithium manganese iron phosphate (LMFP) and lithium nickel cobalt manganese oxide (NCM), binder polyvinylidene fluoride (PVDF), and conductive agent acetylene black, and the mass ratio of the three is 97:2:1. The thickness of the positive electrode current collector aluminum foil is 13 μm, and the positive electrode film layer is located on both sides of the aluminum foil. The area density of the positive electrode film layer is 0.33 g / 1540.25 mm 2The thickness ratio of the positive electrode film layer on the positive electrode current collector side to the positive electrode current collector is 6.1 when the battery cell is configured in a 0% SOC state.

[0352] (2) The negative electrode tab: the negative electrode film layer includes negative electrode active material natural graphite, conductive agent acetylene black, binder styrene butadiene rubber, and thickening agent sodium carboxymethyl cellulose at a mass ratio of 96:1:2:1. The negative electrode current collector is a copper foil with a thickness of 5 μm, and the negative electrode film layer is located on both sides of the copper foil. The area density of the negative electrode film layer is 0.174 g / 1540.25 mm 2 The thickness ratio of the negative electrode film layer on the negative electrode current collector side to the negative electrode current collector is 16 when the battery cell is configured in a 0% SOC state.

[0353] (3) The separator film: a polyethylene (PE) film with a thickness of 5 μm is used as the separator film.

[0354] (4) The electrolyte includes vinylene carbonate (VC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and lithium hexafluorophosphate LiPF6. The mass content of LiPF6 in the electrolyte is 12.5%, the mass content of vinylene carbonate is 1.5%, the mass content of dimethyl carbonate is 16%, the mass content of ethyl methyl carbonate is 28%, and the rest is diethyl carbonate. The conductivity of the electrolyte at 25°C is 9.5 mS / cm.

[0355] (5) The battery cell: including the positive electrode tab, the separator film, and the negative electrode tab arranged in a stack to obtain an electrode assembly, the electrode assembly has a size of 574 mm in a first direction, a size of 120 mm in a second direction, and a size of 17.9 mm in a third direction. The electrode assembly is added to an outer packaging square aluminum shell, and after drying, the electrolyte is injected. After the packaging, high-temperature standing, formation, secondary injection, aging, capacity, and other processes, the battery cell is obtained. The size ratio of the positive electrode film layer in the first direction to the size of the battery cell in the first direction is 93.9%, and the size ratio of the positive electrode film layer in the second direction to the size of the battery cell in the second direction is 93.3%.

[0356] The battery cell also includes a tab portion extending from both sides of the positive electrode tab and the negative electrode tab in the first direction, and the total size L1 of the tab portion in the second direction and the size L of the tab in the second direction is 70%. The tab portion of the present embodiment is arranged according to FIG. 1.

[0357] As shown in FIG. 4, the battery cell further includes two positive electrode poles and two negative electrode poles, the two positive electrode poles are respectively arranged on two side surfaces of the battery cell perpendicular to the first direction, the two negative electrode poles are respectively arranged on two side surfaces of the battery cell perpendicular to the first direction, and the positive electrode poles and the negative electrode poles are oppositely arranged along the first direction. The poles are directly electrically connected with the tab parts of the corresponding polarity.

[0358] The upper limit voltage of the battery cell at normal temperature is 4.2-4.3V.

[0359] The parameters of Examples 2-17, Comparative Examples 1-6 and Example 1 are shown in Table 1.

[0360] Example 4

[0361] The electrolyte includes vinylene carbonate (VC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), LiPF6 and LiFSI, the mass content of LiPF6 in the electrolyte is 8.46%, the mass content of LiFSI is 4.7%, the mass content of vinylene carbonate is 1.5%, the mass content of dimethyl carbonate is 16%, the mass content of ethyl methyl carbonate is 28%, and the rest is diethyl carbonate. The conductivity of the electrolyte at 25°C is 10 mS / cm. The rest of the operations and parameters are the same as in Example 1.

[0362] Example 5

[0363] The electrolyte includes vinylene carbonate (VC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), vinyl sulfide, 1,3-propane sultone, LiPF6 and LiFSI, the mass content of LiPF6 in the electrolyte is 8.46%, the mass content of LiFSI is 4.7%, the mass content of vinylene carbonate is 1.5%, the mass content of dimethyl carbonate is 16%, the mass content of vinyl sulfide is 1.2%, the mass content of 1,3-propane sultone is 1%, the mass content of ethyl methyl carbonate is 28%, and the rest is diethyl carbonate. The conductivity of the electrolyte at 25°C is 10 mS / cm. The rest of the operations and parameters are the same as in Example 1.

[0364] Example 6

[0365] The electrolyte comprises vinylene carbonate (VC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), diethyl carbonate (DEC), vinyl sulfate, 1,3-propane sultone, LiPF6, and LiFSI, the mass content of LiPF6 in the electrolyte is 8.46%, the mass content of LiFSI is 4.7%, the mass content of vinylene carbonate is 1.5%, the mass content of dimethyl carbonate is 16%, the mass content of ethylene carbonate is 28%, the mass content of vinyl sulfate is 1.2%, the mass content of 1,3-propane sultone is 1%, the mass content of ethyl methyl carbonate is 28%, and the rest is diethyl carbonate. The conductivity of the electrolyte at 25°C is 11 mS / cm. The rest of the operations and parameters are the same as in Example 1.

[0366] The electrolyte of Examples 3, 14, and 15 contains 16% by mass of ethyl acetate, and the rest of the examples and comparative examples do not contain ethyl acetate.

[0367] In Examples 1, 4-6, 10-15, and Comparative Examples 2-5, the mass percentage of Ni in the positive electrode film layer is 19.8%. In Examples 2-3, 7-9, 16-17, Comparative Example 1, and Comparative Example 6, the mass percentage of Ni in the positive electrode film layer is 12.02%, 22.58%, 12.02%, 15.61%, 22.58%, 14.82%, 9.88%, 7.98%, and 0%, respectively.

[0368] In Examples 1-15 and Comparative Examples 1-5, the mass percentage of Fe in the positive electrode film layer is 8.51%. In Examples 16-17 and Comparative Example 6, the mass percentage of Fe in the positive electrode film layer is 9.93%, 11.35%, and 14.18%, respectively.

[0369] In Examples 1, 4-6, 10-15, and Comparative Examples 2-5, the plateau voltage is 3.632 V. In Examples 2-3, 7-9, 16-17, and Comparative Examples 1 and 6, the plateau voltage is 3.626 V, 3.634 V, 3.626 V, 3.629 V, 3.634 V, 3.624 V, 3.616 V, 3.623 V, and 3.58 V, respectively.

[0370] Example 18

[0371] Except for the following settings, the rest are the same as in Example 6.

[0372] The positive electrode film layer further comprises lithium supplementing material lithium iron oxide, and the mass percentage of lithium iron oxide in the positive electrode film layer is 0.5%.

[0373] The negative electrode film layer comprises a first negative electrode film layer on the negative electrode current collector and a second negative electrode film layer on the first negative electrode film layer, and the first negative electrode film layer and the second negative electrode film layer comprise natural graphite.

[0374] The nickel cobalt manganese lithium material is a polycrystalline material, and the nickel cobalt manganese lithium material includes spherical particles with a longest diameter of 4-8 μm and spherical particles with a longest diameter of 0.5-2 μm. Based on the mass of the nickel cobalt manganese lithium material, the nickel cobalt manganese lithium material includes the following mass percentages of elements: 0.063% of Al, 0.004% of B, 7.65% of Co, 0.004% of Fe, 6.14% of Li, 2.44% of Mn, 49.86% of Ni, 0.0001% of Sr, 0.0003% of Ti, 0.0008% of Y, and 0.256% of Zr.

[0375] The lithium manganese iron phosphate material includes particles with a longest diameter of 0.1-0.3 μm and particles with a longest diameter of 1-2 μm, and the lithium manganese iron phosphate includes particles with a shape suitable for filling gaps between the spherical particles. Based on the mass of the lithium manganese iron phosphate material, the lithium manganese iron phosphate material includes the following mass percentages of elements: 0.02% of Al, 0.01% of Ca, 0.004% of Cr, 0.005% of Cu, 13.91% of Fe, 0.0009% of K, 4.26% of Li, 0.007% of Mg, 19.72% of Mn, 0.032% of Na, 19.30% of P, 0.003% of Si, 0.046% of Ti, 0.169% of V, and 0.002% of Zn.

[0376] The tested battery power density is 5.46 W / Wh

[0377] Battery test:

[0378] (1) Energy density test of the battery monomer: at 25°C, the battery monomer is charged at 0.33C to a cut-off voltage of 4.25V, then charged at a constant voltage of ≤0.05C, and then discharged at 0.33C to a cut-off voltage of 2.0V, and the discharge energy E0 and the discharge capacity C0 are recorded; the mass of the battery monomer (usually with the battery monomer with a shell) M0 is weighed; the energy density of the battery monomer is E0 / M0, and the unit can be Wh / kg.

[0379] (2) Cycle performance test of the battery monomer:

[0380] At 45°C, the battery monomer is charged at 0.5C to 4.25V, then charged at a constant voltage of 0.05C, and then discharged at 1C to 2.0V, which is one charge-discharge cycle, and the first cycle discharge capacity is recorded; after 10 min, the above charge-discharge cycle is repeated until the battery discharge capacity decays to 80% of the first cycle discharge capacity, and the test is stopped, and the cycle number is recorded.

[0381] (3) Power density test of the battery cell:

[0382] At 25℃, the battery cell is charged at 0.33C constant current to the cut-off voltage 4.25V, then charged at constant voltage to 0.05C, and left for 10min; discharged at 0.33C constant current for 90min to adjust the battery to 50% SOC, record the voltage U1 at this time, then discharged at 3C pulse for 30s, record the voltage after discharge as U2, then the corresponding direct current resistance R = (U1-U2) / 3C0, the power W = discharge cut-off voltage * (U1-discharge cut-off voltage) / R, the power density P = W / E0. Wherein, C0, E0 are measured according to the method in item (1).

[0383] In the following table, the chemical formula of the lithium iron manganese phosphate material also contains M1 elements in addition to Li, Fe, Mn, and the mass content of M1 elements in the lithium iron manganese phosphate material is trace, so it is not expressed in its chemical formula, but it is still considered that M1 elements are contained in the lithium iron manganese phosphate material shown in the table, and the sum of the subscripts of Fe and the subscripts of Mn in the chemical formula of the lithium iron manganese phosphate material and the total moles of M1 elements in the chemical formula is 1. The chemical formula of the lithium nickel cobalt manganese oxide material also contains M2 elements in addition to Li, Ni, Co, Mn, and the mass content of M2 elements in the lithium nickel cobalt manganese oxide material is trace, so it is not expressed in its chemical formula, but it is still considered that M2 elements are contained in the lithium nickel cobalt manganese oxide material shown in the table, and the sum of the subscripts of Ni, Co, and Mn in the chemical formula of the lithium nickel cobalt manganese oxide material and the total moles of M2 elements in the chemical formula is 1. M1 elements and M2 elements can be the same or different.

[0384] Table 4

[0385] From the above table, compared with Example 1, the molar ratio of Ni in the sum of Ni, Co and Mn in Example 2 is reduced, which can improve the cycle performance of the battery cell. Compared with Example 1, the molar ratio of Ni in the sum of Ni, Co and Mn in Example 3 is increased, which can improve the energy density and power performance of the battery cell, the content of the additive VC is increased, and the cycle performance is improved.

[0386] Table 5

[0387] From the above table, it can be seen that:

[0388] Compared with Example 1, the increase of lithium bisfluorosulfonylimide in the lithium salt of the electrolyte of Example 4 is conducive to improving the cycle performance and power performance of the battery monomer. On the basis of Example 4, the increase of vinyl sulfate and 1,3-propanesulfonic acid lactone in the electrolyte of Example 5 is conducive to further improving the cycle performance of the battery monomer. On the basis of Example 5, the increase of ethylene carbonate in the electrolyte of Example 6 is conducive to further improving the cycle performance and power performance of the battery monomer.

[0389] Table 6

[0390] From the above table, it can be seen that:

[0391] Compared with Example 6, the molar ratio of Ni in the total of Ni, Co and Mn is reduced in Examples 7-8, and the cycle performance of the battery monomer is improved accordingly.

[0392] Compared with Example 6, the molar ratio of Ni in the total of Ni, Co and Mn is increased in Example 9, and the energy density and power performance of the battery monomer are improved accordingly.

[0393] Table 7

[0394] From the above table, it can be seen that: compared with Example 6, the mass content of vinylene carbonate in the electrolyte is reduced in Examples 10-11, and the power performance of the battery monomer is improved accordingly. Compared with Example 6, the mass content of ethylene carbonate in the electrolyte is increased in Example 12, and the cycle performance of the battery monomer is improved accordingly.

[0395] Table 8

[0396] From the above table, it can be seen that: compared with Example 6, the conductivity of the electrolyte is improved in Examples 14-15, which can improve the power performance of the battery monomer.

[0397] Table 9

[0398] From the above table, it can be seen that: compared with Example 6, the mass ratio of manganese iron lithium phosphate in the positive active material is increased in Examples 16-17, which can improve the cycle performance of the battery monomer.

[0399] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and embodiments having the same technical idea and playing the same role and effect within the scope of the technical solutions of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications of the embodiments, combination of part of the components in the embodiments to construct other ways can also be included in the scope of the present application.

Claims

1. A battery cell, comprising a positive electrode sheet, a negative electrode sheet, and a non-aqueous electrolyte; the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer on at least one side of the positive electrode current collector, and the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer on at least one side of the negative electrode current collector; wherein, the positive electrode film layer comprises a positive electrode active material, the positive electrode active material comprises a lithium manganese iron phosphate material and a lithium nickel cobalt manganese oxide material; in the lithium nickel cobalt manganese oxide material, the molar percentage of Ni element in the total of Ni, Co, and Mn elements is 0.5-0.95; the non-aqueous electrolyte comprises vinylene carbonate, and the mass content of the vinylene carbonate in the non-aqueous electrolyte is 0.5%-2%; the non-aqueous electrolyte comprises at least one of a linear carbonate and a linear carboxylate, and the conductivity of the non-aqueous electrolyte is 9-14 mS / cm. the non-aqueous electrolyte comprises a linear carbonate, the linear carbonate comprises dimethyl carbonate, and the mass content of the dimethyl carbonate in the non-aqueous electrolyte is 4%-20% or 8%-16%. the non-aqueous electrolyte comprises a linear carboxylate, and the mass content of the linear carboxylate in the non-aqueous electrolyte is 5%-25%. the linear carboxylate comprises at least one of methyl formate, methyl acetate, ethyl formate, and ethyl acetate.

2. The battery cell of claim 1, wherein, the viscosity of the non-aqueous electrolyte at room temperature is 1-3 mPa·s or 2-3 mPa·s.

3. The battery cell of claim 1 or 2, wherein, when the mass percentage of the lithium nickel cobalt manganese oxide material in the positive electrode active material is ≥10%, the non-aqueous electrolyte further comprises a substance containing a sulfur-oxygen bond, and the substance containing a sulfur-oxygen bond comprises at least one of vinyl sulfate and 1,3-propane sultone.

4. The battery cell of any one of claims 1 to 3, wherein, the mass content of the substance containing a sulfur-oxygen bond in the non-aqueous electrolyte is 0.5%-4% or 0.5%-2%.

5. The battery cell of any one of claims 1 to 4, wherein, in the non-aqueous electrolyte, the mass ratio of the 1,3-propane sultone to the vinyl sulfate is greater than 0 and less than 1.

6. The battery cell of any one of claims 1 to 5, wherein, the non-aqueous electrolyte further comprises a lithium salt, and the mass content of the lithium salt in the non-aqueous electrolyte is 12%-16%.

7. The battery cell of claim 6, wherein, when the mass percentage of the lithium nickel cobalt manganese oxide material in the positive electrode active material is ≥20%, the lithium salt comprises lithium hexafluorophosphate and a lithium fluorosulfonylamide salt, and the lithium fluorosulfonylamide salt comprises at least one of lithium monofluorosulfonylimide, lithium bifluorosulfonylimide, and lithium trifluorosulfonylimide.

8. The battery cell of claim 6 or 7, wherein, the lithium salt comprises lithium hexafluorophosphate and lithium bifluorosulfonylimide, and the mass ratio of the lithium hexafluorophosphate to the lithium bifluorosulfonylimide is 1.23:1-4.28:

1.

9. The battery cell of any one of claims 1-8, wherein, the non-aqueous electrolyte further comprises vinylene carbonate, and the mass content of the vinylene carbonate in the non-aqueous electrolyte is 12%-35%.

10. The battery cell of claim 9, wherein, the mass percentage of Ni element in the positive electrode film layer is 5.1%-25%, the mass percentage of Fe element in the positive electrode film layer is 6%-15%, and the mass content of the vinylene carbonate in the non-aqueous electrolyte is 1%-1.5%.

11. The battery cell of claim 10, wherein, the mass percentage of the lithium manganese iron phosphate material in the positive electrode active material is 50%-90%.

12. The battery cell of any one of claims 1-11, wherein, ​ 13. The battery cell of any one of claims 1-12, wherein, ​ 14. The battery cell of claim 13, wherein, ​ 15. The battery cell according to any one of claims 1 to 14, wherein, The mass percentage of the lithium manganese iron phosphate material in the positive electrode active material is 60%-80%; in the lithium nickel cobalt manganese oxide material, the molar percentage of Ni element in the total of Ni, Co and Mn elements is 0.7-0.

95.

16. The battery cell of any one of claims 1-15, wherein, The lithium manganese iron phosphate material further comprises one or more elements selected from Al, B, Ca, Cr, K, Mg, Ni, Co, Na, Si, Ti, V, Cu, Zn, S, Sc, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, Cl, C, N, F.

17. The battery cell of claim 16, wherein One or more of the following: The mass percentage of Al element in the lithium manganese iron phosphate material is 0.01%-0.03%; The mass percentage of Ca element in the lithium manganese iron phosphate material is 0.005%-0.02%; The mass percentage of Cr element in the lithium manganese iron phosphate material is 0.0018%-0.004%; The mass percentage of Cu element in the lithium manganese iron phosphate material is 0.00275%-0.006%; The mass percentage of Fe element in the lithium manganese iron phosphate material is 6.955%-14%; The mass percentage of K element in the lithium manganese iron phosphate material is 0.00045%-0.001%; The mass percentage of Li element in the lithium manganese iron phosphate material is 3%-4.5%; The mass percentage of Mg element in the lithium manganese iron phosphate material is 0.003%-0.007%; The mass percentage of Mn element in the lithium manganese iron phosphate material is 9.86%-20%; The mass percentage of Na element in the lithium manganese iron phosphate material is 0.016%-0.04%; The mass percentage of P element in the lithium manganese iron phosphate material is 9.65%-20%; The mass percentage of Si element in the lithium manganese iron phosphate material is 0.00125%-0.003%; The mass percentage of Ti element in the lithium manganese iron phosphate material is 0.023%-0.05%; The mass percentage of V element in the lithium manganese iron phosphate material is 0.0845%-0.18%; The mass percentage of Zn element in the lithium manganese iron phosphate material is 0.00115%-0.003%.

18. The battery cell of any one of claims 1-17, wherein, The lithium nickel cobalt manganese oxide material further comprises one or more elements selected from Al, B, Fe, Sr, Ti, Y, Zr, Na, K, Mg, Si, P, S, Ca, Sc, V, Cr, Cu, Zn, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, F.

19. The battery cell of claim 18, wherein One or more of the following: The mass percentage of Al element in the lithium nickel cobalt manganese oxide material is 0.0315%-0.07%; The mass percentage of B element in the lithium nickel cobalt manganese oxide material is 0.00195%-0.005%; The mass percentage of Co element in the lithium nickel cobalt manganese oxide material is 3.825%-8%; The mass percentage of Fe element in the lithium nickel cobalt manganese oxide material is 0.0016%-0.004%; The mass percentage of Li element in the lithium nickel cobalt manganese oxide material is 5.5%-6.8%; The mass percentage of Mn element in the lithium nickel cobalt manganese oxide material is 1.22%-2.8%; The mass percentage of Ni element in the lithium nickel cobalt manganese oxide material is 24.93%-51%; The mass percentage of Sr element in the lithium nickel cobalt manganese oxide material is 0.00005%-0.0002%; The mass percentage of Ti element in the lithium nickel cobalt manganese oxide material is 0.00015%-0.0004%; The mass percentage of Y element in the lithium nickel cobalt manganese oxide material is 0.0004%-0.0009%; The mass percentage of Zr element in the lithium nickel cobalt manganese oxide material is 0.128%-0.3%.

20. The battery cell of any one of claims 1-19, wherein, The lithium nickel cobalt manganese oxide material comprises spherical particles, and the lithium manganese iron phosphate material comprises particles suitable for filling the gaps between the spherical particles.

21. The battery cell of any one of claims 1-20, wherein, The lithium nickel cobalt manganese oxide material is a polycrystalline material.

22. The battery cell of any one of claims 1-21, wherein, The lithium nickel cobalt manganese oxide material comprises particles with a longest diameter of 4-8 μm and particles with a longest diameter of 0.5-2 μm.

23. The battery cell of any one of claims 1-22, wherein, The lithium manganese iron phosphate material comprises particles with a longest diameter of 0.1-0.3 μm and particles with a longest diameter of 1-2 μm.

24. The battery cell of any one of claims 1-23, wherein, The positive electrode film layer further comprises a lithium supplement material, and the lithium supplement material comprises one or more of lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganate, lithium tartrate, and trilithium citrate.

25. The battery cell of any one of claims 1-24, wherein, The negative electrode film layer comprises a negative electrode active material, and the negative electrode active material comprises graphite and a silicon material, and the mass percentage of silicon element in the negative electrode film layer is 0.3%-10%.

26. The battery cell of claim 25, wherein, The silicon material comprises one or more of silicon oxide and silicon-carbon composite.

27. The battery cell of claim 25 or 26, wherein, The silicon material comprises silicon-carbon composite, and the mass percentage of silicon element in the negative electrode film layer is 1%-5%.

28. The battery cell of any one of claims 1-27, wherein, The face density of the positive electrode film layer is 0.32 - 0.36 mg / 1540.25 mm 2 .

29. The battery cell of any one of claims 1-28, wherein, The areal density of the negative electrode film layer is 0.169 - 0.190 mg / 1540.25 mm 2 .

30. The battery cell of any one of claims 1-29, wherein, The ratio of the size of the positive electrode film layer in the first direction to the size of the battery cell in the first direction is ≥92%.

31. The battery cell of any one of claims 1-30, wherein, The ratio of the size of the positive electrode film layer in the second direction to the size of the battery cell in the second direction is ≥93%, and the second direction is perpendicular to the first direction.

32. The battery cell of any one of claims 1-31, wherein, In the battery cell configured as a 0% SOC state, the thickness ratio of the positive electrode film layer on any one side of the positive electrode current collector to the positive electrode current collector is 5-8.

33. The battery cell of any one of claims 1-32, wherein, In the battery cell configured as a 0% SOC state, the thickness ratio of the negative electrode film layer on any one side of the negative electrode current collector to the negative electrode current collector is 13-20.

34. The battery cell of any one of claims 1-33, wherein, The negative electrode film layer comprises a first negative electrode film layer on the negative electrode current collector and a second negative electrode film layer on the first negative electrode film layer, and the first negative electrode film layer and the second negative electrode film layer comprise graphite.

35. The battery cell of any one of claims 1-34, wherein, The thickness of the positive electrode current collector is 10-13 μm.

36. The battery cell of any one of claims 1-35, wherein, The thickness of the negative electrode current collector is 4-5.5 μm.

37. The battery cell of any one of claims 1-36, wherein, The electrode assembly comprises at least two positive electrode sheets and at least two negative electrode sheets, the positive electrode sheets and the negative electrode sheets are arranged in layers; the positive electrode sheet and / or the negative electrode sheet comprises a tab portion and a main body portion, the tab portion extends from the main body portion along a first direction, the ratio of the total size L1 of the joint area of the tab portion and the main body portion in a second direction to the size L of the main body portion in the second direction is ≥ 50%, and the second direction is perpendicular to the first direction.

38. The battery cell of any one of claims 1-37, wherein, The battery cell comprises at least two poles of the same polarity, and the poles are directly electrically connected with the tab portion of the corresponding polarity.

39. The battery cell of any one of claims 1-38, wherein, The battery cell comprises two positive poles and two negative poles, the two positive poles are arranged on the two sides of the battery cell perpendicular to the first direction respectively, the two negative poles are arranged on the two sides of the battery cell perpendicular to the first direction respectively, and the positive poles and the negative poles are arranged opposite to each other along the first direction.

40. The battery cell of any one of claims 1-39, wherein, The size of the electrode assembly in the first direction is 400-1000 mm.

41. The battery cell of any one of claims 1-40, wherein, The size of the electrode assembly in the second direction is 90-120 mm, and the second direction is perpendicular to the first direction.

42. The battery cell of any one of claims 1-41, wherein, The size of the electrode assembly in the third direction is 13-25 μm, and the third direction is perpendicular to both the first direction and the second direction.

43. The battery cell of any one of claims 1-42, wherein, The battery cell is discharged at 1 / 3C from 4.25 V to 2.0 V, and the platform voltage is 3.574-3.63 V or 3.595-3.63 V.

44. The battery cell of any one of claims 1-43, wherein, The energy density of the battery cell is 210-250 Wh / kg.

45. The battery cell of any one of claims 1-44, wherein, The upper limit voltage of the battery cell at room temperature is 4.2-4.3 V.

46. A battery device comprising the battery cell of any one of claims 1 to 45; the battery device comprises a battery module, a battery pack or an energy storage device.

47. A power utilization device comprising the battery cell of any one of claims 1 to 45 or the battery device of claim 46.

48. The powered device of claim 47, wherein, The power utilization device is a vehicle, and the length direction of the battery cell or the battery device is parallel to the driving direction of the vehicle.

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