Negative electrode piece, preparation method thereof and lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries, and relates to a negative electrode plate, a preparation method thereof and a lithium ion battery. The negative electrode plate comprises a negative current collector, a first active coating and a second active coating; the first active coating coats on a long paste coating surface of the negative current collector; the second active coating coats a short paste coating surface of the negative current collector; and the first active coating and the second active coating are both negative electrode active materials containing artificial graphite. Artificial graphite with different gram capacities is realized by controlling the graphitization temperature, and the overpotential of the long paste coating surface of the negative current collector and the diffusion impedance between the long paste coating surfaces of a positive electrode and a negative electrode are reduced by setting the artificial graphite in the first active coating and the artificial graphite in the second active coating to have different gram capacities and OI values, and therefore, the polarization of a high-voltage lithium cobalt oxide in the cycle process can be reduced, and the lithium precipitation phenomenon and the capacity retention ratio of a high-voltage lithium cobalt oxide lithium ion battery prepared by adopting the negative electrode plate in the cycle process are improved.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a negative pole piece, a preparation method thereof, and a lithium ion battery. Background technique [0002] Lithium cobalt oxide material has the advantages of high voltage and high compaction density as the positive electrode material of lithium ion battery. It is an ideal positive electrode material for lithium ion battery. However, under the normal charging voltage of about 4.2V, the capacity of lithium cobalt oxide material is limited. , increasing the charging voltage of the lithium cobalt oxide battery can increase the volumetric energy density of the battery. Therefore, the research on lithium-ion batteries is now turned to high-voltage (charging voltage ≥ 4.45V) lithium cobalt oxide as the positive electrode material of lithium-ion batteries, which can increase the volumetric energy density of the battery, but the polarization is large during t...

AI Technical Summary

Problems solved by technology

[0002]Lithium cobalt oxide material has the advantages of high voltage and high compaction density as the positive electrode material of lithium ion battery, and is an ideal positive electrode material for lithium ion battery, but in conventional 4.2 At a charging voltage of around V, the capacity of lithium cobalt oxide materials is limited, and increasing the charging voltage of lithium cobalt oxide batteries can increase the volumetric energy density of the battery

Therefore, the research on lithium-ion batteries is now turned to high-voltage (charging voltage ≥ 4.45V) lithium cobalt oxide as the positive electrode material of lithium-ion batteries, which can increase the volumetric energy density of the battery, but the polarization is large during the cycle, and it is prone to precipitation. Lithium and fast capacity fading and other problems are currently mainly solved by improving the kinetic properties of the negative electrode, but they cannot be completely solved.

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