CN-122025803-A - Battery cell, battery device and electricity utilization device

Abstract

The application relates to the technical field of lithium ion batteries, in particular to a battery cell, a battery device and an electricity utilization device. The battery monomer comprises an electrode assembly and electrolyte used for infiltrating the electrode assembly, the electrode assembly comprises an anode plate, an isolating film and a cathode plate, the electrode assembly is of a lamination structure, the cathode plate comprises a cathode current collector and a cathode film layer positioned on at least one side of the cathode current collector, the cathode film layer comprises a cathode active material, the cathode active material comprises a graphite material, and the electrolyte comprises a carboxylate solvent. According to the application, the content of the carboxylate solvent is reduced to slow down the transmission speed of lithium ions, so that the lithium ion intercalation speed is better matched with the intercalation speed of the anode active material, the anode active material with a low OI value is adopted, the overall lithium intercalation speed is improved, the lithium accumulation on the anode surface during quick charge is effectively reduced, and the lithium precipitation tendency is reduced.

Inventors

• DU YANG
• KANG MENG
• SHEN RUI

Assignees

• 宁德时代新能源科技股份有限公司

Dates

Publication Date

20260512

Application Date

20260414

Priority Date

20250806

Claims (20)

1. 1. A battery cell, characterized in that the battery cell comprises an electrode assembly and electrolyte for infiltrating the electrode assembly, The electrode assembly comprises an anode pole piece, a separation film and a cathode pole piece, the electrode assembly is a lamination structure, The negative electrode plate comprises a negative electrode current collector and a negative electrode film layer positioned on at least one side of the negative electrode current collector, wherein the negative electrode film layer comprises a negative electrode active material, the OI value of the negative electrode active material is 2-6, and the negative electrode active material comprises a graphite material; the thickness of the isolating film is 5-10 mu m; The electrolyte comprises a carboxylate solvent, wherein the mass ratio of the carboxylate solvent is 10-30% based on the total mass of the solvent and the additive in the electrolyte.
2. 2. The battery cell according to claim 1, wherein the anode active material has an OI value of 2.5 to 5.5.
3. 3. The battery cell of claim 1, wherein the carboxylate-based solvent comprises 15-25% by mass based on the total mass of solvent and additives in the electrolyte.
4. 4. A battery cell according to any one of claims 1 to 3, wherein the carboxylic acid ester solvent comprises one or more of ethyl acetate, methyl formate, methyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate.
5. 5. The battery cell of any one of claims 1-3, wherein the separator comprises a base film and a coating on at least one side of the base film, the base film comprising one or more of fiberglass, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.
6. 6. The battery cell of claim 5, wherein the base film has a thickness of 2.5 μιη to 10.5 μιη.
7. 7. The battery cell of claim 5, wherein the coating comprises a first coating and a second coating stacked in sequence, the first coating being positioned on a side proximate to the positive electrode tab, the first coating comprising polyvinylidene fluoride, the second coating comprising a ceramic material.
8. 8. The battery cell of claim 7, wherein one or more of the following conditions are satisfied, the thickness of the first coating layer is 0.5-3 μm and the thickness of the second coating layer is 0.5-3 μm.
9. 9. The battery cell of claim 5, wherein the coating comprises a third coating proximate a side of the negative electrode tab, the third coating comprising polyvinylidene fluoride.
10. 10. The battery cell of claim 9, wherein the third coating has a thickness of 0.5 μιη to 3 μιη.
11. 11. The battery cell of any one of claims 1-3, wherein one or more of the following conditions are met, the separator has a porosity of 25% -60%, and the separator has a permeability of 90s/100cc-260s/100cc.
12. 12. A battery cell according to any one of claims 1 to 3, wherein the graphite material has a volume average particle diameter Dv50 of 7 μm to 13 μm.
13. 13. A battery cell according to any one of claims 1-3, wherein the negative electrode active material has a median of I D /I G of 0.1-0.6, wherein I G represents a G peak intensity at 1580±100cm -1 of the raman spectrum of the negative electrode active material, and I D represents a D peak intensity at 1350±100cm -1 of the raman spectrum of the negative electrode active material.
14. 14. A battery cell according to any of claims 1-3, wherein the graphite material comprises artificial graphite.
15. 15. A battery cell according to any of claims 1-3, wherein the graphite material comprises secondary particles formed from primary particles.
16. 16. The battery cell of claim 14, wherein the artificial graphite comprises a first component and a second component, wherein, The method for preparing the first component comprises the steps of crushing needle coke to obtain first graphite primary particles, granulating the first graphite primary particles to obtain graphite secondary particles, performing first heat treatment on the graphite secondary particles to obtain an intermediate, mixing the intermediate with a coating agent, and performing second heat treatment to obtain the first component; The method for preparing the second component comprises the steps of crushing petroleum raw coke to obtain second graphite primary particles, mixing the second graphite primary particles with a coating agent, and carrying out third heat treatment to obtain the second component.
17. 17. A battery cell according to any of claims 1-3, wherein the negative electrode film layer has a single-sided coating weight of 0.05g/1540.25mm 2 -0.2g/1540.25 mm 2 .
18. 18. A battery cell according to any one of claims 1 to 3, wherein the porosity of the negative electrode sheet is 20% to 35%.
19. 19. A battery cell according to any one of claims 1-3, wherein one or more of the following conditions are satisfied, that the thickness of the negative electrode current collector is 2 μm-10 μm and that the thickness of the negative electrode film layer is 40 μm-80 μm.
20. 20. The battery cell of any one of claims 1-3, wherein the negative electrode film layer comprises: the first negative electrode film layer is arranged on at least one side of the negative electrode current collector; The second negative electrode film layer is arranged on one side, away from the negative electrode current collector, of the first negative electrode film layer; Wherein the volume average particle diameter Dv50 of the graphite material in the first negative electrode film layer is greater than or equal to the volume average particle diameter Dv50 of the graphite material in the second negative electrode film layer.

Description

Battery cell, battery device and electricity utilization device Cross Reference to Related Applications The present application claims the priority benefit of international application number PCT/CN2025/113080 filed on month 8 and 6 of 2025 and is incorporated herein in its entirety. Technical Field The present disclosure relates to the field of lithium ion batteries, and in particular, to battery cells, battery devices, and electrical devices. Background Lithium ion batteries are not only applied to energy storage power supply systems such as hydraulic power, firepower, wind power and solar power stations, but also widely applied to electric vehicles such as electric bicycles, electric motorcycles, electric automobiles, and the like, as well as a plurality of fields such as military equipment, aerospace, and the like. However, the current battery cells still have a plurality of problems in practical application, and further improvement is needed. Disclosure of Invention In a first aspect of the application, the application provides a battery cell, which comprises an electrode assembly and electrolyte used for infiltrating the electrode assembly, wherein the electrode assembly comprises a positive electrode plate, a separation film and a negative electrode plate, the electrode assembly is of a lamination structure, the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer positioned on at least one side of the negative electrode current collector, the negative electrode film layer comprises a negative electrode active material, the OI value of the negative electrode active material is 2-6, the negative electrode active material comprises a graphite material, the thickness of the separation film is 5-10 mu m, the electrolyte comprises a carboxylate solvent, and the mass ratio of the carboxylate solvent is 10-30% based on the total mass of the solvent and the additive in the electrolyte. According to the application, the transmission speed of lithium ions is slowed down by reducing the content of the carboxylate solvent, so that the intercalation speed of the carboxylate solvent and the anode active material is better matched, the accumulation of lithium ions on the surface of the anode is reduced, the lithium precipitation risk is reduced, and the growth of lithium dendrites is reduced. The application adopts the negative electrode active material with low OI value, can enhance the direction selective intercalation of lithium ions, namely lithium ions can be intercalated from the end face of the negative electrode active material, and can be rapidly diffused through interlayer defects or inclined crystal faces, thereby improving the overall lithium intercalation rate, effectively reducing the lithium accumulation on the surface of the negative electrode during rapid charging, reducing the lithium precipitation tendency, and in addition, the negative electrode active material with low OI value has better electrolyte wettability, and can further improve the lithium ion transmission efficiency at the interface. In some embodiments, the anode active material has an OI value of 2.5 to 5.5. Therefore, the volume expansion and reaction kinetics of the anode active material are improved, the intercalation of lithium ions is accelerated, the quick charge performance of the battery monomer is improved, the volume expansion effect of the anode piece can be effectively relieved, and the cycle performance and storage performance of the battery monomer are improved. In some embodiments, the carboxylate solvent comprises 15% to 25% by mass based on the total mass of solvent and additives in the electrolyte. Thus, the viscosity of the electrolyte can be reduced, the ionic conductivity of the electrolyte can be improved, and the side reaction between the carboxylate solvent and the anode active material can be reduced. In some embodiments, the carboxylic acid ester solvent comprises one or more of ethyl acetate, methyl formate, methyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate. The carboxylic ester solvent has low viscosity and can accelerate the transmission of lithium ions. In some embodiments, the separator film includes a base film and a coating on at least one side of the base film. Therefore, the interface contact with the pole piece of the isolating film can be improved, and the growth of lithium dendrite is reduced, so that the cycle life of the battery is prolonged, and the quick charge performance is improved. In some embodiments, the base film comprises one or more of fiberglass, nonwoven, polyethylene, polypropylene, and polyvinylidene fluoride. Therefore, the base film can provide basic mechanical properties (such as stretch resistance and puncture resistance), reduce the damage of the coating during the processing and using processes and maintain the integrity of the whole structure. In