Positive pole piece, preparation method thereof and lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a positive pole piece, a preparation method thereof and a lithium ion battery. The positive pole piece comprises a positive current collector, a first active coating and a second active coating, a long paste coating surface and a short paste coating surface of the positive current collector are coated with the first active coating, the surface of the first active coating is coated with the second active coating, the first active coating and the second active coating are both positive active materials containing high-voltage lithium cobalt oxide, and the high-voltage lithium cobalt oxide contains a modified element aluminum. Different lithium cobalt oxide gram capacities and modification element aluminum contents are set in the first active coating and the second active coating, and overpotentials on two sides of the positive electrode current collector are reduced, so that polarization of high-voltage lithium cobalt oxide in the circulation process can be reduced, and the lithium precipitation phenomenon and the capacity retention rate of the high-voltage lithium cobalt oxide in the circulation process are improved.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a positive 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, and is an ideal positive electrode material for lithium ion battery. However, under the conventional 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 d...

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. However, under the conventional 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 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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