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; the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises a lithium iron phosphate material and a lithium nickel manganese cobalt oxide material; in the positive electrode active material, the molar ratio of a Ni element to the total amount of three elements, i.e., 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 a linear carbonate and a linear carboxylate, and has an electrical conductivity of 9-14 mS / cm. The energy density, cycle performance and power performance of the battery cell are simultaneously improved.

Description

Battery cell, battery device, and electric device

[0001] This application is based on Chinese Patent Application No. 202411293343.1, filed on September 14, 2024, and Chinese Patent Application No. 202411088506.2, filed on August 8, 2024, and claims priority to them, 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 an electric device. BACKGROUND

[0003] In recent years, with the application range of batteries becoming 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. Due to the great development of batteries, higher requirements are 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 an electric 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, 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, 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 iron phosphate material and a lithium nickel cobalt manganese oxide material; in the positive electrode active 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 a stable component on the surface of the negative electrode to improve the stability of the SEI film of the negative electrode and can 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, is also conducive to making up for the power loss caused by the mixing of the lithium iron phosphate material, and is also conducive to reducing the negative impact of excessively high conductivity on the high-temperature cycle performance, so as to ensure 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 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 lithium material in the positive electrode active material is ≥10%, in order to take advantage of the capacity of the nickel-cobalt-manganese lithium material, the upper limit voltage of the battery is based on the nickel-cobalt-manganese lithium material, the substance containing the sulfur-oxygen bond is formed on the positive electrode under high voltage, the composition of the positive electrode interfacial film is optimized, the side reaction between the surface residual alkali of the nickel-cobalt-manganese lithium material and the acidic substance in the electrolyte is inhibited, and the cycle performance of the battery is improved.

[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 is greater than the mass of the 1,3-propanesultone, which 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 greater than or equal to 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 bisfluorosulfonylimide, and lithium trifluorosulfonylimide.

[0022] In this way, the inclusion of lithium hexafluorophosphate and a lithium fluorosulfonylamide 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; and at the same time, it is also conducive to improving the cycle performance and power performance of the battery.

[0023] In any embodiment, 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.

[0024] In this way, the ratio of lithium hexafluorophosphate to lithium bisfluorosulfonylimide 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 bisfluorosulfonylimide 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, improving the power performance of the battery while ensuring the cycle 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 in the positive electrode film layer is 4.5%-25%, the mass ratio of Fe in the positive electrode film layer is 15%-33%, and the mass content of the vinylene carbonate in the non-aqueous electrolyte is 1%-1.5%.

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

[0029] Thus, when the mass ratio of the lithium iron phosphate material in the positive electrode active material is high, the structural stability is increased, and the cycle performance and safety performance can be improved.

[0030] In any embodiment, the mass ratio of the lithium iron phosphate material in the positive electrode active material is 60%-80%, and the molar ratio of Ni in the total of Ni, Co, and Mn in the positive electrode active material is 0.7-0.95.

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

[0032] In any embodiment, the lithium iron phosphate material further comprises one or more elements selected from Al, B, Ca, Cr, K, Mg, Ni, Co, Mn, 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 iron phosphate material comprises one or more of the following:

[0034] The mass ratio of Al in the lithium iron phosphate material is 0.01%-0.02%;

[0035] The mass ratio of B in the lithium iron phosphate material is 0.08%-0.09%;

[0036] The mass ratio of Ca in the lithium iron phosphate material is 0.0001%-0.0003%;

[0037] The mass ratio of Fe in the lithium iron phosphate material is 16.035%-35%;

[0038] The mass ratio of K in the lithium iron phosphate material is 0.0022%-0.0050%;

[0039] The mass ratio of Li in the lithium iron phosphate material is 3%-4.5%;

[0040] The mass ratio of Mg in the lithium iron phosphate material is 0.00235%-0.0052%;

[0041] The mass ratio of Mn in the lithium iron phosphate material is 0.00205%-0.0050%;

[0042] The mass percentage of Na element in the lithium iron phosphate material is 0.018%-0.05%;

[0043] The mass percentage of P element in the lithium iron phosphate material is 9.265%-19.5%;

[0044] The mass percentage of Si element in the lithium iron phosphate material is 0.0065%-0.02%;

[0045] The mass percentage of Ti element in the lithium iron phosphate material is 0.074%-0.16%;

[0046] The mass percentage of V element in the lithium iron phosphate material is 0.0003%-0.0008%;

[0047] The mass percentage of Cr element in the lithium iron phosphate material is 0.0004%-0.0012%;

[0048] The mass percentage of Zn element in the lithium iron phosphate material is 0.00005%-0.0003%.

[0049] In any embodiment, the lithium nickel cobalt manganese oxide material further comprises one or more elements 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] The mass percentage of Al element in the lithium nickel cobalt manganese oxide material is 0.0315%-0.07%;

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

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

[0054] The mass percentage of Fe element in the lithium nickel cobalt manganese oxide material is 0.0016%-0.005%;

[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 the element Ni in the lithium nickel cobalt manganese oxide material is 24.93%-51%;

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

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

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

[0061] The mass percentage of the element Zr 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 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 lithium nickel cobalt manganese oxide particles with different particle sizes 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 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 lithium iron phosphate particles with different particle sizes 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, and the negative electrode active material comprises graphite and a silicon material, and the mass percentage of the element silicon in the negative electrode film layer is 0.3%-10%. In this way, it is beneficial to improve the energy density of the battery.

[0068] In any embodiment, the silicon material comprises one or more of silicon oxide, 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%. Thereby, the energy density of the battery is improved.

[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] Thereby, the energy density of the battery is improved.

[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 is perpendicular to the first direction.

[0075] Thereby, the utilization rate of the electrode assembly is improved.

[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] Thereby, the energy density and kinetic performance of the battery are improved at the same time.

[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. Thereby, the kinetic performance of the battery is further improved.

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

[0081] In any embodiment, the thickness of the negative electrode 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 two sides of the battery cell perpendicular to the first direction, the two negative poles are respectively arranged on 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 battery cell is configured to be discharged from 4.25 V to 2.0 V at 1 / 3 C, and the platform voltage is 3.25-3.44 V or 3.32-3.44 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 charging voltage of the battery cell at room temperature is 4.2-4.3 V.

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

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

[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 present 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 iron phosphate material and a 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;

[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, wherein the mass content of the chain ester compound in the non-aqueous electrolyte is 8%-16%.

[0103] 3. The battery cell according to any one of the first or second aspects, wherein 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 the first to third aspects, wherein the conductivity of the non-aqueous electrolyte is 9-14 mS / cm.

[0105] 5. The battery cell according to any one of the first to fourth aspects, 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 methyl ethyl 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 greater than or equal to 10%, the non-aqueous 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 non-aqueous electrolyte is 0.5% to 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 greater than 20%, the non-aqueous electrolyte further comprises component B, and the component B comprises one or more of lithium hexafluorophosphate and lithium bisfluorosulfonylimide.

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

[0113] 13. The battery cell according to aspect 11 or 12, wherein the mass content of the component B in the non-aqueous electrolyte is 12% to 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 bisfluorosulfonylimide is 1.5:1 to 5:1.

[0115] 15. The battery cell according to any one of aspects 1 to 14, wherein the non-aqueous electrolyte further comprises vinyl carbonate, and the mass content of the vinyl carbonate in the non-aqueous 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 ratio of the lithium iron phosphate material in the positive electrode film layer is 50% to 90%, the mass ratio of the Fe element in the positive electrode film layer is 15% to 33%, the mass ratio of the Ni element in the positive electrode film layer is 4.5% 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 iron phosphate material in the positive electrode film layer is 60-80%, the mass percentage of Fe element in the positive electrode film layer is 20-28%, the mass percentage of Ni element in the positive electrode film layer is 9-20%, and the molar percentage of Ni element in the total of Ni, Co, and Mn elements is 0.7-0.95.

[0118] 18. The battery cell according to any one of aspects 1 to 17, wherein the lithium iron phosphate material further comprises one or more elements selected from Al, B, Ca, Cr, K, Mg, Ni, Co, Mn, 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:

[0120] the mass percentage of Al element in the lithium iron phosphate material is 0.01-0.02%;

[0121] the mass percentage of B element in the lithium iron phosphate material is 0.08-0.09%;

[0122] the mass percentage of Ca element in the lithium iron phosphate material is 0.0001-0.0003%;

[0123] the mass percentage of Fe element in the lithium iron phosphate material is 16.035-35%;

[0124] the mass percentage of K element in the lithium iron phosphate material is 0.0022-0.0050%;

[0125] the mass percentage of Li element in the lithium iron phosphate material is 3-4.5%;

[0126] the mass percentage of Mg element in the lithium iron phosphate material is 0.00235-0.0052%;

[0127] the mass percentage of Mn element in the lithium iron phosphate material is 0.00205-0.0050%;

[0128] the mass percentage of Na element in the lithium iron phosphate material is 0.018-0.05%;

[0129] the mass percentage of P element in the lithium iron phosphate material is 9.265-19.5%;

[0130] a mass percentage of Si in the lithium iron phosphate material is 0.0065%-0.02%;

[0131] a mass percentage of Ti in the lithium iron phosphate material is 0.074%-0.16%;

[0132] a mass percentage of V in the lithium iron phosphate material is 0.0003%-0.0008%.

[0133] 20. The battery cell according to any one of aspects 1 to 19, the lithium nickel cobalt manganese oxide material further comprising 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.

[0134] 21. The battery cell according to aspect 20, comprising one or more of:

[0135] a mass percentage of Al in the lithium nickel cobalt manganese oxide material is 0.0315%-0.07%;

[0136] a mass percentage of B in the lithium nickel cobalt manganese oxide material is 0.00195%-0.005%;

[0137] a mass percentage of Co in the lithium nickel cobalt manganese oxide material is 3.825%-8%;

[0138] a mass percentage of Fe in the lithium nickel cobalt manganese oxide material is 0.0016%-0.004%;

[0139] a mass percentage of Li in the lithium nickel cobalt manganese oxide material is 5.5%-6.8%;

[0140] a mass percentage of Mn in the lithium nickel cobalt manganese oxide material is 1.22%-2.8%;

[0141] a mass percentage of Ni in the lithium nickel cobalt manganese oxide material is 24.93%-51%;

[0142] a mass percentage of Sr in the lithium nickel cobalt manganese oxide material is 0.00005%-0.0002%;

[0143] a mass percentage of Ti in the lithium nickel cobalt manganese oxide material is 0.00015%-0.0004%;

[0144] a mass percentage of Y in the lithium nickel cobalt manganese oxide material is 0.0004%-0.0009%;

[0145] The mass percentage of Zr in the lithium nickel cobalt manganese oxide material is 0.128%-0.3%.

[0146] 22. The battery cell according to any one of aspects 1 to 21, wherein the lithium nickel cobalt manganese oxide material comprises spheroid-like particles, and the lithium iron phosphate material comprises particles with a shape suitable for filling gaps between the spheroid-like particles.

[0147] 23. The battery cell according to any one of aspects 1 to 22, wherein the lithium nickel cobalt manganese oxide material comprises particles with a longest diameter of 4-8 pm, and the lithium iron phosphate material comprises particles with a shortest diameter of 0.1-0.3 pm.

[0148] 24. The battery cell according to any one of aspects 1 to 23, wherein the lithium nickel cobalt manganese oxide material comprises particles with a shortest diameter of 0.5-2 pm, and the lithium iron phosphate material comprises particles with a longest diameter of 1-3 pm.

[0149] 25. The battery cell according to any one of aspects 1 to 24, wherein the lithium nickel cobalt manganese oxide material is a polycrystalline material.

[0150] 26. The battery cell according to any one of aspects 1 to 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.

[0151] 27. The battery cell according to any one of aspects 1 to 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%.

[0152] 28. The battery cell according to aspect 27, wherein the silicon material comprises one or more of silicon oxide and silicon-carbon composite.

[0153] 29. The battery cell according to aspect 27 or 28, wherein the silicon material comprises silicon-carbon composite, and the mass percentage of silicon in the negative electrode film layer is 1%-5%.

[0154] 30. The battery cell according to any one of aspects 1 to 29, wherein the areal density of the positive electrode film layer is 0.32-0.36 mg / 1540.25 mm 2 .

[0155] 31. The battery cell according to any one of aspects 1 to 30, wherein the areal density of the negative electrode film layer is 0.169-0.190 mg / 1540.25 mm 2 .

[0156] 32. The battery cell of any one of aspects 1 to 31, the positive electrode tab having a height that is > 93% of the height of the electrode assembly.

[0157] 33. The battery cell of any one of aspects 1 to 32, the positive electrode tab having a length that is > 92% of the length of the electrode assembly.

[0158] 34. The battery cell of any one of aspects 1 to 33, the battery full discharge state being the state reached at 25 °C by discharging at 0.33 C to 2.0 V and then at 0.05 C to 2.0 V; in the battery full discharge state, the thickness ratio of the positive electrode film layer to the positive current collector is > 10 or 12-14.

[0159] 35. The battery cell of any one of aspects 1 to 34, the battery full discharge state being the state reached at 25 °C by discharging at 0.33 C to 2.0 V and then at 0.05 C to 2.0 V; in the battery full discharge state, the positive electrode film layer has a compacted density of 2.85-2.95 g / cm 3 .

[0160] 36. The battery cell of any one of aspects 1 to 35, the battery full discharge state being the state reached at 25 °C by discharging at 0.33 C to 2.0 V and then at 0.05 C to 2.0 V; in the battery full discharge state, the thickness ratio of the negative electrode film layer to the negative current collector is > 30 or 33-35.

[0161] 37. The battery cell of any one of aspects 1 to 36, the battery full discharge state being the state reached at 25 °C by discharging at 0.33 C to 2.0 V and then at 0.05 C to 2.0 V; in the battery full discharge state, the negative electrode film layer has a compacted density of 1.4-1.5 g / cm 3 .

[0162] 38. The battery cell of any one of aspects 1 to 37, the negative electrode film layer comprising a first negative electrode film layer on the negative current collector and a second negative electrode film layer on the first negative electrode film layer, the first and second negative electrode film layers comprising graphite.

[0163] 39. The battery cell of any one of aspects 1 to 38, the positive current collector having a thickness of < 15 pm or 10-13 pm.

[0164] 40. The battery cell of any one of aspects 1 to 39, the negative current collector having a thickness of < 6 pm or 4-5.5 pm.

[0165] 41. The battery cell according to any one of aspects 1 to 40, further comprising a tab, the tab being arranged along a height direction of the positive electrode tab, a ratio of a total height of the tab to the height of the positive electrode tab being > 50%.

[0166] 42. The battery cell according to any one of aspects 1 to 41, further comprising a post, the post being two.

[0167] 43. The battery cell according to any one of aspects 1 to 42, further comprising a tab and a post, the tab being directly connected to the post.

[0168] 44. The battery cell according to any one of aspects 1 to 43, further comprising a housing, the housing being made of aluminum, a wall thickness of the housing being 0.2 - 0.3 mm.

[0169] 45. The battery cell according to any one of aspects 1 to 44, a ratio of a length to a height of the electrode assembly being 4 - 7.

[0170] 46. The battery cell according to any one of aspects 1 to 45, the length of the electrode assembly being 400 - 600 mm.

[0171] 47. The battery cell according to any one of aspects 1 to 46, the height of the electrode assembly being 90 - 120 mm.

[0172] 48. The battery cell according to any one of aspects 1 to 47, a thickness of the electrode assembly being 13 - 25 pm.

[0173] 49. The battery cell according to any one of aspects 1 to 48, a platform voltage of the battery cell discharged from 4.25 V to 2.0 V at 1 / 3 C being 3.25 - 3.44 V or 3.32 - 3.44 V.

[0174] 50. The battery cell according to any one of aspects 1 to 49, an energy density of the battery cell being 210 - 250 Wh / kg.

[0175] 51. The battery cell according to any one of aspects 1 to 50, a charge upper limit voltage of the battery cell at room temperature being 4.2 - 4.3 V.

[0176] 52. A battery device comprising the battery cell according to any one of aspects 1 to 51; the battery device comprising a battery module, a battery pack or an energy storage device.

[0177] 53. A device consuming electric power comprising the battery cell according to any one of aspects 1 to 51 or the battery device according to aspect 52.

[0178] 54. The power consuming device according to the aspect 53, wherein the power consuming device is a vehicle, and the length direction of the battery cell or battery device is parallel to a traveling direction of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0179] FIG. 1 is a schematic view of a positive electrode tab or negative electrode tab structure according to an embodiment of the present application.

[0180] FIG. 2 is a schematic view of a positive electrode tab or negative electrode tab structure according to another embodiment of the present application.

[0181] FIG. 3 is a schematic view of a positive electrode tab or negative electrode tab structure according to another embodiment of the present application.

[0182] FIG. 4 is a schematic view of a battery cell and a tab structure according to an embodiment of the present application.

[0183] FIG. 5 is a schematic view of an electrode assembly according to an embodiment of the present application.

[0184] FIG. 6 is an exploded view of a battery cell according to an embodiment of the present application.

[0185] FIG. 7 is a schematic view of a battery pack according to an embodiment of the present application.

[0186] FIG. 8 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 7.

[0187] 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.

[0188] 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 electrode tab; 64 negative electrode tab. DETAILED DESCRIPTION

[0189] Hereinafter, embodiments of the battery cell, battery module, battery pack, and power consuming device according to the present application are specifically disclosed with appropriate reference to the accompanying drawings. However, there are cases where unnecessary detailed description is omitted. For example, there are cases where detailed description of matters that are well known, repeated description of actually identical structures are omitted. This is to avoid the following description becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0190] The ranges disclosed herein are intended to be "open" ranges, i.e., the upper and lower limits of the range are not included. The ranges are also intended to include any and all sub-ranges of the same, wherein any statement of a range can be read to include any and all sub-ranges within the original stated range. For example, a stated range of 60% to 120% should be considered to include any and all sub-ranges between (and including) the minimum value of 60% and the maximum value of 120%, i.e., all sub-ranges beginning with a minimum value of 60% or more and ending with a maximum value of 120% or less, e.g., 60% to 120%, 60% to 121%, 61% to 120%, 62% to 120%, 63% to 120%, 64% to 120%, 65% to 120%, and so forth; as well as, for example, any smaller selected sub-ranges within the indicated range, e.g., 65 to 69, 65.1 to 69.9, 65.11 to 69.76, 65.11 to 69.13, etc. For example, if a range of 80-110 is listed, it is understood that 80-110, 80-111, 81-110, 81-111, 82-110, 82-111, etc. are also contemplated. In other words, any maximum value of a range can be replaced with a minimum value or any minimum value of a range can be replaced with a maximum value. It is specifically intended that the scope of each range actually indicates any and all sub-ranges subsumed within the indicated range. It must be noted that, as used in the specification and the appended claims, the singular form "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component" or "the component" can include a plurality of components, and so forth.

[0191] Unless otherwise indicated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0192] Unless otherwise indicated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0193] Unless otherwise indicated, all steps of the present application can be performed in sequence or randomly, and are preferably performed in sequence. For example, a method includes steps (a) and (b), which means that the method can include steps (a) and (b) performed in sequence, or steps (b) and (a) performed 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.

[0194] [Battery cell]

[0195] The battery cell is also called a rechargeable battery or a storage battery, which refers to a battery that can be activated by charging after discharging.

[0196] Generally, a battery cell includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During the charging and discharging of the battery, active ions (e.g., lithium ions) are inserted and extracted between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet, mainly to prevent short circuiting of the positive and negative electrodes, while allowing 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.

[0197] One embodiment of the present application provides 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 comprising a positive electrode current collector and a positive electrode film layer on at least one side of the positive electrode current collector, the negative electrode sheet comprising a negative electrode current collector and a negative electrode film layer on at least one side of the negative electrode current collector; wherein,

[0198] The positive electrode film layer comprises a positive electrode active material, the positive electrode active material comprising a lithium iron phosphate material and a lithium nickel cobalt manganese oxide material; in the positive electrode active material, the molar percentage 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; in some embodiments, since the lithium iron phosphate material does not contain Ni element or contains a trace amount of Ni element, the "molar percentage of Ni element in the total of Ni, Co, and Mn elements" can also be calculated based on the element content in the lithium nickel cobalt manganese oxide material.

[0199] 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;

[0200] 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, 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.

[0201] The lithium nickel cobalt manganese oxide material and the lithium iron phosphate material are mixed to have the advantages of high energy density at low cost, so as to make up for the lack of energy density range between single lithium iron phosphate battery and single lithium nickel cobalt manganese oxide battery. However, the lithium nickel cobalt manganese oxide material with high nickel content has the advantage of high specific capacity, which is beneficial to improve the energy density of the battery. However, the lithium nickel cobalt manganese oxide material with high nickel content has a high surface residual alkali content, which is easy to react with the acid in the electrolyte to generate water. The water will accelerate the generation of acid in the electrolyte, and the generated acid will 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. In addition, the power performance of the lithium iron phosphate material is not as good as that of the lithium nickel cobalt manganese oxide material, so mixing the lithium iron phosphate material into the positive electrode active material will cause a loss of the power performance of the battery.

[0202] 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 low-power lithium iron phosphate material. 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 impedance of the SEI film, is also beneficial to make up for the power loss caused by the mixing of the lithium iron phosphate material, and is also beneficial to reduce the negative impact of too high electrical conductivity on high-temperature cycle performance. Ensure that the battery has high energy density while improving the cycle performance and power performance of the battery.

[0203] In the present application, the molar proportion of Ni element 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, the material in the positive electrode film layer is collected, and the mass content of Ni, Co and Mn elements is tested by ICP, and then the molar proportion of Ni element in the total of Ni, Co and Mn elements is calculated.

[0204] 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.

[0205] 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.

[0206] 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.

[0207] In some embodiments, the linear carboxylic acid ester comprises at least one of methyl formate, methyl acetate, ethyl formate, and ethyl acetate.

[0208] 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.

[0209] 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.

[0210] 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.

[0211] 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.

[0212] 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.

[0213] Thus, 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 composition 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.

[0214] In some embodiments, 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.

[0215] Thus, 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.

[0216] In this application, the mass content of the vinyl sulfate and the 1,3-propane sultone in the non-aqueous electrolyte is tested by conventional methods in the art. For example, gas chromatography is used.

[0217] 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.

[0218] 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 fluorosulfonylamide salt, and the lithium fluorosulfonylamide salt comprises at least one of lithium monofluorosulfonylimide, lithium bisfluorosulfonylimide, and lithium trifluorosulfonylimide.

[0219] Thus, the lithium hexafluorophosphate and the lithium fluorosulfonylamide 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.

[0220] 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 formed by any of the above values.

[0221] 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.

[0222] 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 formed by any of the above values.

[0223] 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, thereby improving the power performance of the battery while ensuring the cycle performance of the battery; on the other hand, the above content can inhibit the side reaction of ethylene carbonate with the positive electrode active material, thereby improving the cycle performance and safety performance of the battery.

[0224] In this application, the mass content of ethylene carbonate in the non-aqueous electrolyte is tested by conventional methods in the art. For example, gas chromatography is used.

[0225] In some embodiments, the mass percentage of Ni element in the positive electrode film layer is 4.5%-25% (for example, 4.5%, 5%, 7%, 9%, 10%, 12%, 14%, 15%, 17%, 19%, 20%, 22%, 24%, 25%, or a range formed by any of the above values), the mass percentage of Fe element in the positive electrode film layer is 15%-33% (for example, 15%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 31%, 32%, 33%, or a range formed by 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 formed by any of the above values).

[0226] In the embodiments of the present application, the types and contents of the organic components 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 composition of the electrolyte can be detected by liquid chromatography, gas chromatography, ion chromatography, liquid nuclear magnetic 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 method for gas chromatography of chemical reagents".

[0227] In the embodiments of the present application, the test sample can be the freshly prepared electrolyte or the free electrolyte obtained from the battery after the battery is fully discharged (discharged to the lower limit cutoff voltage so that the charged state of the battery is about 0% SOC).

[0228] In the present application, the mass content of the linear carbonate, vinylene carbonate, ethylene sulfate, 1,3-propane sultone, vinyl carbonate and linear carboxylic acid ester in the non-aqueous electrolyte can be tested by the conventional method in the art. For example, gas chromatography is used. The specific operation conditions of the gas chromatography can 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; and the carrier flow rate is 1.5 mL / min.

[0229] In the embodiments of the present application, the types and contents of the inorganic components / 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 inorganic components / lithium salt concentration in the electrolyte can be qualitatively or quantitatively analyzed by ion chromatography according to the standard JY / T020-1996 "General method for ion chromatography analysis". In the embodiments of the present application, the freshly prepared electrolyte or the free electrolyte obtained from the battery after the battery is fully discharged (discharged to the lower limit cutoff voltage so that the charged state of the battery is about 0% SOC) can be used as the sample, and the ion chromatography analysis method is used for detection.

[0230] In some embodiments, the mass ratio of the lithium 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.

[0231] Therefore, when the mass ratio of the lithium iron phosphate material in the positive electrode active material is high, the structural stability is increased, and the cycle performance and safety performance can be improved.

[0232] In the present application, the mass percentage 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 percentage of each element in the positive electrode film layer is tested by ICP.

[0233] In some embodiments, the mass percentage of the lithium iron 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); in the positive electrode active material, the molar percentage of Ni element in the total of Ni, Co, and Mn 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.

[0234] Thus, while maintaining the cost advantage, the battery has good energy density and cycle performance.

[0235] In some embodiments, the lithium iron phosphate material further comprises one or more elements selected from Al, B, Ca, Cr, K, Mg, Ni, Co, Mn, 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.

[0236] In some embodiments, the lithium iron phosphate material comprises one or more of the following:

[0237] The mass percentage of Al element in the lithium iron phosphate material is 0.01%-0.02%;

[0238] The mass percentage of B element in the lithium iron phosphate material is 0.08%-0.09%;

[0239] The mass percentage of Ca element in the lithium iron phosphate material is 0.0001%-0.0003%;

[0240] The mass percentage of Fe element in the lithium iron phosphate material is 16.035%-35%;

[0241] The mass percentage of K element in the lithium iron phosphate material is 0.0022%-0.0050%;

[0242] The mass percentage of Li element in the lithium iron phosphate material is 3%-4.5%;

[0243] The mass percentage of Mg element in the lithium iron phosphate material is 0.00235%-0.0052%;

[0244] Mn element in the mass fraction of the lithium iron phosphate material is 0.00205%-0.0050%;

[0245] Na element in the mass fraction of the lithium iron phosphate material is 0.018%-0.05%;

[0246] P element in the mass fraction of the lithium iron phosphate material is 9.265%-19.5%;

[0247] Si element in the mass fraction of the lithium iron phosphate material is 0.0065%-0.02%;

[0248] Ti element in the mass fraction of the lithium iron phosphate material is 0.074%-0.16%;

[0249] V element in the mass fraction of the lithium iron phosphate material is 0.0003%-0.0008%;

[0250] Cr element in the mass fraction of the lithium iron phosphate material is 0.0004%-0.0012%;

[0251] Zn element in the mass fraction of the lithium iron phosphate material is 0.00005%-0.0003%.

[0252] In some embodiments, the lithium nickel cobalt manganese oxide material further comprises one or more elements 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.

[0253] In some embodiments, the lithium nickel cobalt manganese oxide material comprises one or more of the following:

[0254] Al element in the mass fraction of the lithium nickel cobalt manganese oxide material is 0.0315%-0.07%;

[0255] B element in the mass fraction of the lithium nickel cobalt manganese oxide material is 0.00195%-0.005%;

[0256] Co element in the mass fraction of the lithium nickel cobalt manganese oxide material is 3.825%-8%;

[0257] Fe element in the mass fraction of the lithium nickel cobalt manganese oxide material is 0.0016%-0.005%;

[0258] Li element in the mass fraction of the lithium nickel cobalt manganese oxide material is 5.5%-6.8%;

[0259] The mass percentage of the element Mn in the lithium nickel cobalt manganese oxide material is 1.22% to 2.8%;

[0260] The mass percentage of the element Ni in the lithium nickel cobalt manganese oxide material is 24.93% to 51%;

[0261] The mass percentage of the element Sr in the lithium nickel cobalt manganese oxide material is 0.00005% to 0.0002%;

[0262] The mass percentage of the element Ti in the lithium nickel cobalt manganese oxide material is 0.00015% to 0.0004%;

[0263] The mass percentage of the element Y in the lithium nickel cobalt manganese oxide material is 0.0004% to 0.0009%;

[0264] The mass percentage of the element Zr in the lithium nickel cobalt manganese oxide material is 0.128% to 0.3%.

[0265] In some embodiments, the lithium nickel cobalt manganese oxide material comprises spheroid-like particles, and the lithium iron phosphate material comprises particles with a shape suitable for filling the gaps between the spheroid-like particles. In this way, the compaction density of the positive electrode active material is improved, thereby improving the energy density of the battery. Moreover, the spheroid-like lithium cobalt manganese oxide material is mostly secondary particle morphology, which has good power performance.

[0266] In some embodiments, 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 conducive to improving the power of the battery.

[0267] In some embodiments, 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 conducive to improving the compaction density of the positive electrode active material and improving the energy density of the battery.

[0268] In some embodiments, the lithium 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. In this way, the combination of different particle sizes of lithium iron phosphate particles is conducive to improving the compaction density of the positive electrode active material and improving the energy density of the battery.

[0269] In some embodiments, the "longest diameter" refers to: cutting the positive electrode sheet comprising 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 periphery edge line of the particle is the "longest diameter" of the particle.

[0270] In the present application, the longest diameter of the particles of the lithium 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 into a positive electrode sheet, the positive electrode sheet is washed thoroughly with DMC (dimethyl carbonate), and the positive electrode sheet is dried, the positive electrode sheet is cut along the thickness direction to expose the longitudinal section of the positive electrode film layer, since the particle morphology of the lithium iron phosphate material and the lithium nickel cobalt manganese oxide material is different, it can be distinguished, for the lithium iron phosphate particles (or lithium nickel cobalt manganese particles), measure multiple times from different directions of each particle by SEM, take the maximum measurement value as the longest diameter, test multiple (for example 10-100) particles of each material.

[0271] In some embodiments, the positive electrode film layer further comprises a lithium supplement material, 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, trilithium citrate. This is beneficial to improve the energy density of the battery.

[0272] In some embodiments, the negative electrode film layer comprises a negative electrode active material, the negative electrode active material comprises graphite and a silicon material, the mass percentage of silicon element 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. This is beneficial to improve the energy density of the battery.

[0273] In the present application, the mass percentage of silicon element in the negative electrode film layer is tested by conventional methods in the art. For example, the battery monomer is disassembled, the negative electrode sheet is taken out, the negative electrode sheet is washed thoroughly with DMC (dimethyl carbonate), and the negative electrode sheet is dried, the material in the negative electrode film layer is collected, and the mass percentage of silicon element in the negative electrode film layer is tested by ICP.

[0274] In some embodiments, the silicon material comprises one or more of silicon oxide and silicon-carbon composite.

[0275] 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.

[0276] 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 2or a range consisting of any of the aforementioned values.

[0277] 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 aforementioned values.

[0278] Thereby, the energy density of the battery is improved.

[0279] In the present 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 tab (negative electrode tab) 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 tab (negative electrode tab) is measured. The weight of the positive electrode tab (negative electrode tab) 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).

[0280] In some embodiments, 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%.

[0281] In some embodiments, 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%, the second direction being perpendicular to the first direction.

[0282] Thereby, the utilization rate of the electrode assembly is improved.

[0283] In some embodiments, when the battery cell is configured to a 0% SOC state, i.e., at 25°C, discharged at 0.33C to 2.0V, and then discharged at 0.05C to 2.0V, the thickness ratio of the positive electrode film layer on any one side of the positive current collector to the positive current collector is 5-8.

[0284] In some embodiments, when the battery cell is configured to a 0% SOC state, i.e. at 25℃, discharged at 0.33C to 2.0V, and then discharged at 0.05C to 2.0V, the thickness ratio of the negative electrode film layer on either side of the negative current collector to the negative current collector is 13-20.

[0285] Thus, the energy density and kinetic performance of the battery are simultaneously improved.

[0286] In some embodiments, the negative electrode film layer comprises a first negative electrode film layer on the negative 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. Thus, the kinetic performance of the battery is further improved.

[0287] In some embodiments, the thickness of the positive current collector is 10-13 μm.

[0288] In some embodiments, the thickness of the negative current collector is 4-5.5 μm.

[0289] Thus, the energy density of the battery is improved.

[0290] In some embodiments, the electrode assembly comprises at least two positive electrode sheets and at least two negative electrode sheets, and the positive electrode sheets and the negative electrode sheets are arranged in layers; as shown in FIG. 1 (the figure shows a single sheet), 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 in a first direction, and the ratio of the total size L1 of the interface region between 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%, and the second direction is perpendicular to the first direction.

[0291] In some embodiments, as shown in FIG. 2 (the figure shows a single sheet), 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 in a first direction, the sizes of the interface regions between 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%, and the second direction is perpendicular to the first direction.

[0292] In some embodiments, as shown in FIG. 3 (a single tab is shown in the figure), the positive tab and / or the negative tab comprises a main body part 62 and a tab part 61 extending from the main body part 62 in a first direction, the tab part 61 is trapezoidal, and the ratio of the total size L1 of the joint area of the tab part 61 and the main body part 62 in a second direction to the size L of the main body part 62 in the second direction is ≥ 50%, the second direction being perpendicular to the first direction.

[0293] In some embodiments, the battery cell comprises at least two poles of the same polarity, and the poles are directly electrically connected with the tab part of the corresponding polarity.

[0294] 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 two sides of the battery cell 5 perpendicular to the first direction, the two negative poles 64 are respectively arranged on 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 in the first direction.

[0295] 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.

[0296] In some embodiments, the size of the electrode assembly in the first direction is 400-1000 mm.

[0297] In some embodiments, the size of the electrode assembly in the second direction is 90-120 mm, the second direction being perpendicular to the first direction.

[0298] In some embodiments, the size of the electrode assembly in the third direction is 13-25 μm, the third direction being perpendicular to both the first direction and the second direction.

[0299] Thus, while ensuring the fast charging performance of the battery, the energy density of the battery is improved.

[0300] In some embodiments, the battery cell is configured to be discharged from 4.25 V to 2.0 V at 1 / 3 C, and the platform voltage is 3.25-3.44 V or 3.32-3.44 V.

[0301] Thus, the platform voltage of the battery is improved, and the energy density of the battery is improved.

[0302] When the mass ratio of lithium iron phosphate in the positive electrode film layer is 50%-90%, the platform voltage of the battery cell discharged from 4.25V to 2.0V at 1 / 3C can be 3.25-3.44V. When the mass ratio of lithium iron phosphate in the positive electrode film layer is 60%-80%, the platform voltage of the battery cell discharged from 4.25V to 2.0V at 1 / 3C can be 3.32-3.44V.

[0303] In the present application, the test method of the platform voltage is as follows: the battery cell is charged to 4.25V at a certain current (for example, 1 / 3C), and then discharged from 4.25V to 2.0V at 1 / 3C, and the platform voltage value is obtained according to the discharge curve.

[0304] In some embodiments, the energy density of the battery cell is 210-250Wh / kg.

[0305] In the present 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 ≤0.05C, and then discharged at a certain current to the discharge cut-off voltage, 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 (A0xV) / M0, and the unit can be Wh / kg.

[0306] In some embodiments, the upper limit of the charging voltage of the battery cell at room temperature is 4.2-4.3V. In this way, the energy density of the battery is improved.

[0307] [Positive electrode sheet]

[0308] During the charging and discharging process of the battery, Li is deintercalated and consumed, and the molar content of Li is different when the battery is discharged to different states. In the present application, the molar content of Li in the listing of the positive electrode material is the initial state of the material, i.e., the state before feeding, and the positive electrode material is applied to the battery system. After charging and discharging cycles, the molar content of Li changes.

[0309] In the present application, the molar content of O in the listing of the positive electrode material is only the theoretical state value, and 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 fluctuate.

[0310] 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.

[0311] In some embodiments, the positive current collector can employ a metal foil or a composite current collector. For example, as a metal foil, an aluminum 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 (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base material (e.g., a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0312] In some embodiments, the positive active material can also employ a positive active material for a battery known in the art. These positive active materials can be used alone only or in combination of two or more. Among them, examples can include, but are not limited to, at least one of lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 O2) and modified compounds thereof, etc., lithium manganese phosphate (e.g., LiMnPO4), and a composite material of lithium manganese phosphate and carbon.

[0313] In some embodiments, the positive electrode film layer can further 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.

[0314] 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 conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0315] In some embodiments, the positive electrode tab can be prepared by dispersing the above-described components for preparing the positive electrode tab, such as the positive 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 the positive current collector, and then drying, cold-pressing, etc., to obtain the positive electrode tab.

[0316] [Negative electrode tab]

[0317] As an example, the negative 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 opposite surfaces of the negative current collector.

[0318] In some embodiments, the negative current collector can employ a metal foil or a composite current collector. For example, as a metal foil, 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.).

[0319] In some embodiments, the negative active material can also employ a negative active material for a battery known in the art. As an example, the negative active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can be selected from at least one of elemental tin, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative active material for a battery can also be used. These negative active materials can be used alone or in combination of two or more.

[0320] In some embodiments, the negative film layer can also 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).

[0321] In some embodiments, the negative film layer can also optionally include a conductive agent. As an example, the conductive agent can be selected from at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0322] In some embodiments, the negative film layer can also optionally include other auxiliary agents, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0323] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-described components for preparing the negative electrode sheet, such as the negative 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 current collector, and then performing processes such as drying and cold pressing to obtain the negative electrode sheet.

[0324] [Electrolyte]

[0325] The electrolyte functions to conduct ions between the positive electrode sheet and the negative electrode sheet. The type of electrolyte is not particularly limited in the present application and can be selected as desired. For example, the electrolyte can be liquid, gel, or all-solid.

[0326] In some embodiments, the electrolyte is liquid and includes an electrolyte salt and a solvent.

[0327] 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 oxalato borate, lithium difluoro dioxalato borate, lithium difluoro dioxalato phosphate, and lithium tetrafluoro oxalato phosphate.

[0328] 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.

[0329] In some embodiments, the electrolyte solution 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 that can improve certain properties of the battery, such as an additive that improves overcharge performance of the battery, an additive that improves high or low temperature performance of the battery, etc.

[0330] [Separator]

[0331] In some embodiments, the battery cell further includes a separator. The type of separator is not particularly limited in the present application and any known porous structure separator having good chemical stability and mechanical stability can be used.

[0332] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single layer film or a multi-layer composite film and is not particularly limited. When the separator is a multi-layer composite film, the materials of the layers can be the same or different and are not particularly limited.

[0333] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be made into an electrode assembly through a winding process or a stacking process.

[0334] 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.

[0335] 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, etc. The outer package of the battery cell can also be a soft package, such as a pouch soft package. The material of the soft package can be plastic, and as plastic, polypropylene, polybutylene terephthalate, polybutylene succinate, etc. can be listed.

[0336] The shape of the battery cell is not particularly limited in the present application, and it 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.

[0337] 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 provided on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator can form the electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, which can be selected by those skilled in the art according to the specific actual needs.

[0338] In some embodiments, the battery cell can be assembled into a battery module, and the number of battery cells contained in the battery module can be one or more, which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0339] In the battery module, the plurality of battery cells can be arranged in sequence along the length direction of the battery module. Of course, they can also be arranged in any other way. Further, the plurality of battery cells can be fixed by fasteners.

[0340] Optionally, the battery module can further include a housing having a receiving space, and the plurality of battery cells are received in the receiving space.

[0341] In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0342] 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 provided on the lower box body 3 to form a closed space for receiving the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any way.

[0343] In addition, the application also provides a power utilization device, which comprises at least one of the battery monomer, the battery module or the battery pack provided by the application. The battery monomer, 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.

[0344] As the power utilization device, the battery monomer, the battery module or the battery pack can be selected according to the use requirements thereof.

[0345] 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 requirements of high power and high energy density of the battery monomer for the power utilization device, the battery pack or the battery module can be used.

[0346] Embodiment 1

[0347] (1) Positive electrode sheet: the positive electrode film layer comprises positive electrode active material lithium iron phosphate (LFP) and lithium nickel cobalt manganese oxide (NCM), binder polyvinylidene fluoride (PVDF) and conductive agent acetylene black, the mass ratio of the three being 97:2:1, the positive electrode current collector aluminum foil has a thickness of 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 0.34 g / 1540.25 mm 2 In the 0% SOC state of the battery monomer, the thickness ratio of the positive electrode film layer on one side of the positive electrode current collector to the positive electrode current collector is 5.73.

[0348] (2) Negative electrode sheet: the negative electrode film layer comprises negative electrode active material natural graphite, conductive agent acetylene black, binder styrene butadiene rubber and thickening agent sodium carboxymethyl cellulose, the mass ratio of the four being 96:1:2:1. The negative electrode current collector is a copper foil with a thickness of 4.5 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 0.18 g / 1540.25 mm 2 In the 0% SOC state of the battery monomer, the thickness ratio of the negative electrode film layer on one side of the negative electrode current collector to the negative electrode current collector is 16.3.

[0349] (3) Separating film: a polyethylene (PE) film is used as the separating film, and the thickness is 5 μm.

[0350] (4) The electrolyte includes vinylene carbonate (VC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and 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.

[0351] (5) The battery cell includes a positive electrode sheet, a separator, and a negative electrode sheet arranged in a stack to obtain an electrode assembly, the size of the electrode assembly in the first direction is 574 mm, the size in the second direction is 120 mm, and the size in the third direction is 17.9 mm. The electrode assembly is added to a square aluminum shell for packaging, and after drying, the electrolyte is injected. After the processes of packaging, high-temperature standing, formation, secondary injection, aging, and capacity, the battery cell is obtained. 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 93.9%, and 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 93.3%.

[0352] The battery cell also includes a tab portion extending from the positive electrode sheet and the negative electrode sheet on both sides in the first direction, and the total size L1 of the tab portion in the second direction and the size L of the electrode sheet in the second direction is 70%. The tab portion of the present embodiment is arranged according to FIG. 1.

[0353] As shown in FIG. 4, the battery cell also includes two positive electrode posts and two negative electrode posts, the two positive electrode posts are arranged on the two sides of the battery cell perpendicular to the first direction, the two negative electrode posts are arranged on the two sides of the battery cell perpendicular to the first direction, and the positive electrode posts and the negative electrode posts are arranged opposite to each other in the first direction. The post is directly electrically connected with the tab portion of the corresponding polarity.

[0354] The upper limit voltage of the battery cell at room temperature is 4.2-4.3 V.

[0355] The parameters of Examples 2-17, Comparative Examples 1-6, and Example 1 are shown in Table 1.

[0356] Example 4

[0357] The electrolyte comprises vinylene carbonate (VC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), LiPF6and LiFSI, the mass content of LiPF6in 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.

[0358] Example 5

[0359] The electrolyte comprises vinylene carbonate (VC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethylene sulfate, 1,3-propane sultone, LiPF6and LiFSI, the mass content of LiPF6in 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 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 10 mS / cm. The rest of the operations and parameters are the same as in Example 1.

[0360] Example 6

[0361] The electrolyte comprises vinylene carbonate (VC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethylene sulfate, 1,3-propane sultone, LiPF6and LiFSI, the mass content of LiPF6in 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 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 10 mS / cm. The rest of the operations and parameters are the same as in Example 1.

[0362] The electrolyte of Examples 3, 14 and 15 contains 16% mass content of ethyl acetate, and the rest of the examples and comparative examples do not contain ethyl acetate.

[0363] 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%, 23%, 12.02%, 15.6%, 23%, 14.82%, 9.88%, 7.98%, and 0%, respectively.

[0364] In Examples 1-15 and Comparative Examples 1-5, the mass percentage of Fe in the positive electrode film layer is 21.2%. In Examples 16-17 and Comparative Example 6, the mass percentage of Fe in the positive electrode film layer is 24.75%, 28.28%, and 35.36%, respectively.

[0365] In Examples 1, 4-6, 10-15, and Comparative Examples 2-5, the plateau voltage is 3.396 V. In Examples 2-3, 7-9, 16-17, and Comparative Examples 1 and 6, the plateau voltage is 3.39 V, 3.401 V, 3.39 V, 3.393 V, 3.401 V, 3.349 V, 3.306 V, 3.388 V, and 3.2 V, respectively.

[0366] Example 18

[0367] Except for the following settings, the rest are the same as those in Example 6.

[0368] 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%.

[0369] 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.

[0370] The lithium nickel cobalt manganese oxide material is a polycrystalline material, and the lithium nickel cobalt manganese oxide material comprises 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 lithium nickel cobalt manganese oxide material, the lithium nickel cobalt manganese oxide material comprises the following mass percentages of elements: 0.063% of Al element, 0.004% of B element, 7.65% of Co element, 0.004% of Fe element, 6.14% of Li element, 2.44% of Mn element, 49.86% of Ni element, 0.0001% of Sr element, 0.0003% of Ti element, 0.0008% of Y element, and 0.256% of Zr element.

[0371] The lithium 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 iron phosphate includes particles with a shape suitable for filling the gaps between the spherical particles. Based on the mass of the lithium iron phosphate material, the lithium iron phosphate material includes the following mass proportions of elements: 0.018% of Al element, 0.0002% of Ca element, 0.0009% of Cr element, 32.07% of Fe element, 0.0044% of K element, 3.92% of Li element, 0.0047% of Mg element, 0.0041% of Mn element, 0.036% of Na element, 18.53% of P element, 0.013% of Si element, 0.148% of Ti element, 0.0006% of V element, and 0.0001% of Zn element.

[0372] The tested battery power density is 5.44 W / Wh.

[0373] Example 19

[0374] The negative active material is natural graphite and silicon-carbon composite (mass ratio of silicon element and carbon element is 1:1, and the manufacturer is G14), and the mass proportion of silicon element in the negative active material is 2.5%. The remaining parameters are the same as those in Example 6.

[0375] The tested battery energy density is 230 Wh / kg.

[0376] Battery test:

[0377] (1) Energy density test of the battery monomer: at 25°C, the battery monomer is charged at 0.33C constant current to the cut-off voltage 4.25V, then charged at constant voltage to ≤0.05C, and then discharged at 0.33C constant current to the cut-off voltage 2.0V, and the discharge energy E0 and the discharge capacity C0 are recorded; the mass of the battery monomer (usually the battery monomer with the shell is weighed) M0 is weighed; the energy density of the battery monomer is E0 / M0, and the unit can be Wh / kg.

[0378] (2) Cycle performance test of the battery monomer:

[0379] At 45°C, the battery monomer is charged at 0.5C constant current to 4.25V, then charged at constant voltage to 0.05C, and then discharged at 1C constant current 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.

[0380] (3) Power density test of the battery monomer:

[0381] The battery monomer is charged at 0.33C constant current to the cut-off voltage 4.25V at 25°C, then charged to 0.05C constant voltage, and left for 10min; discharged at 0.33C0 constant current for 90min to adjust the battery to 50% SOC, record the voltage U1 at this time, then pulse discharge at 3C0 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).

[0382] In the following table, the chemical formula of the lithium iron phosphate material also contains M1 elements in addition to Li and Fe, and the mass content of the M1 elements in the lithium iron phosphate material is trace, so it is not expressed in its chemical formula, but it is still considered that the M1 elements are contained in the lithium iron phosphate material shown in the table, and the sum of the subscript of Fe in the chemical formula of the lithium iron phosphate material and the total number of 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 and Mn, and the mass content of the 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 the 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 number of moles of M2 elements in the chemical formula is 1. The M1 elements and the M2 elements can be the same or different.

[0383] Table 4

[0384] 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 monomer. 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 monomer, the content of the additive VC is increased, and the cycle performance is improved.

[0385] Table 5

[0386] From the above table, it can be seen that:

[0387] 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 cell. Based on 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 cell. Based on 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 cell.

[0388] Table 6

[0389] From the above table, it can be seen that:

[0390] 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 cell is improved accordingly.

[0391] 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 cell are improved accordingly.

[0392] Table 7

[0393] 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 cell 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 cell is improved accordingly.

[0394] Table 8

[0395] 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 cell.

[0396] Table 9

[0397] From the above table, it can be seen that: compared with Example 6, the mass ratio of lithium iron phosphate in the positive active material is increased in Examples 16-17, which can improve the cycle performance of the battery cell.

[0398] 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 an electrode assembly, the electrode assembly comprising a positive electrode tab, a negative electrode tab and a non-aqueous electrolyte; the positive electrode tab comprising 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 tab comprising a negative electrode current collector and a negative electrode film layer located 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 comprising a lithium iron phosphate material and a lithium nickel cobalt manganese oxide material; in the positive electrode active 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, 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 comprising dimethyl carbonate, 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, 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; the viscosity of the non-aqueous electrolyte at room temperature is 1-3 mPa·s or 2-3 mPa·s; 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, the substance containing a sulfur-oxygen bond comprising at least one of vinyl sulfate and 1,3-propane sultone; the mass content of the substance containing a sulfur-oxygen bond in the non-aqueous electrolyte is 0.5%-4% or 0.5%-2%; 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; the non-aqueous electrolyte further comprises a lithium salt, the mass content of the lithium salt in the non-aqueous electrolyte is 12%-16%; 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, the lithium fluorosulfonamide salt comprising at least one of lithium monofluorosulfonimide, lithium bifluorosulfonimide and lithium trifluorosulfonimide; 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; the non-aqueous electrolyte further comprises vinylene carbonate, the mass content of the vinylene carbonate in the non-aqueous electrolyte is 12%-35%; the mass percentage of Ni element in the positive electrode film layer is 4.5%-25%, the mass percentage of Fe element in the positive electrode film layer is 15%-33%, and the mass content of the vinylene carbonate in the non-aqueous electrolyte is 1%-1.5%; the mass percentage of the lithium iron phosphate material in the positive electrode active material is 50%-90%. ​ ​ ​ 2. The battery cell of claim 1, wherein, ​ 3. The battery cell of claim 1 or 2, wherein, ​ 4. The battery cell of any one of claims 1 to 3, wherein, ​ 5. The battery cell of any one of claims 1 to 4, wherein, ​ 6. The battery cell of any one of claims 1 to 5, wherein, ​ 7. The battery cell of claim 6, wherein, ​ 8. The battery cell of claim 6 or 7, wherein, ​ 9. The battery cell of any one of claims 1-8, wherein, ​ 10. The battery cell of claim 9, wherein, ​ 11. The battery cell of claim 10, wherein, ​ 12. The battery cell of any one of claims 1-11, wherein, ​ 13. The battery cell of any one of claims 1-14, wherein, ​ 14. The battery cell of claim 13, wherein, ​ 15. The battery cell of any one of claims 1-14, wherein, The mass percentage of the lithium iron phosphate material in the positive electrode active material is 60%-80%; in the positive electrode active 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 iron phosphate material further comprises one or more elements selected from Al, B, Ca, Cr, K, Mg, Ni, Co, Mn, 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 iron phosphate material is 0.01%-0.02%; The mass percentage of B element in the lithium iron phosphate material is 0.08%-0.09%; The mass percentage of Ca element in the lithium iron phosphate material is 0.0001%-0.0003%; The mass percentage of Fe element in the lithium iron phosphate material is 16.035%-35%; The mass percentage of K element in the lithium iron phosphate material is 0.0022%-0.0050%; The mass percentage of Li element in the lithium iron phosphate material is 3%-4.5%; The mass percentage of Mg element in the lithium iron phosphate material is 0.00235%-0.0052%; The mass percentage of Mn element in the lithium iron phosphate material is 0.00205%-0.0050%; The mass percentage of Na element in the lithium iron phosphate material is 0.018%-0.05%; The mass percentage of P element in the lithium iron phosphate material is 9.265%-19.5%; The mass percentage of Si element in the lithium iron phosphate material is 0.0065%-0.02%; The mass percentage of Ti element in the lithium iron phosphate material is 0.074%-0.16%; The mass percentage of V element in the lithium iron phosphate material is 0.0003%-0.0008%; The mass percentage of Cr element in the lithium iron phosphate material is 0.0004%-0.0012%; The mass percentage of Zn element in the lithium iron phosphate material is 0.00005%-0.0003%.

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%-0.005%; 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 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 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 configured to be discharged by 1 / 3C from 4.25 V to 2.0 V, and the platform voltage is 3.25-3.44 V or 3.32-3.44 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 of the charging 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 1-45; 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 1-45 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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