Preparation method of lithium ion battery cathode

Abstract

The invention provides a preparation method of a lithium ion battery cathode. The active substances of the cathode comprise a first active substance, a second active substance and a third active substance, the first active substance is LiNi0. 8Co0. 1Mn0. 1O2, and D50 is 1.5-1.7 [mu] m; the second active substance is LiNi0. 4Co0. 3Mn0. 3O2, and the D50 is 600 to 650 nm; the third active substance is LiCo0. 5Mn0. 47Al0. 03O2, and D50 is 2.5 to 2.8 [mu] m. The preparation method comprises the steps of preparing the first active substance, the second active substance and the third active substanceinto the first slurry, the second slurry and the third slurry respectively, then mixing the first slurry and the second slurry in proportion to obtain the fourth slurry, and mixing the second slurryand the third slurry in proportion to obtain the fifth slurry; coating and drying the first slurry, the fourth slurry, the second slurry, the fifth slurry and the third slurry in sequence to obtain acathode active material layer, and then coating the surface of the active material layer with a nano Al2O3 passivation layer to obtain the battery cathode. The cathode prepared by the preparation method of the invention has the relatively higher high-temperature rate capability and high-temperature cycle performance.

Description

technical field [0001] The invention relates to the technical field of lithium ion battery production, in particular to a preparation method of a lithium ion battery cathode. Background technique [0002] At present, ternary materials have high energy density and high temperature resistance, and are widely used in the field of power lithium-ion batteries. In the existing technology, in order to achieve the optimal performance of the pole piece, most of them are mixed positive electrodes of ternary materials. A variety of ternary materials in different proportions are mixed and coated together to form a positive electrode. However, due to the uniform distribution of various ternary materials, the mixed positive electrode cannot give full play to the characteristics of each material. Based on the above problems, the present invention provides a The cathode preparation method, by layering the ternary materials, achieves the purpose of giving full play to the ternary materials o...

AI Technical Summary

Problems solved by technology

[0002] At present, ternary materials have high energy density and high temperature resistance, and are widely used in the field of power lithium-ion batteries. In the existing technology, in order to achieve the optimal performance of the pole piece, most of them are mixed positive electrodes of ternary materials. A variety of ternary materials in different proportions are mixed and coated together to form a positive electrode. However, due to the uniform distribution of various ternary materials, the mixed positive electrode cannot give full play to the characteristics of each material. Based on the above problems, the present invention provides a The cathode preparation method, by layering the ternary materials, achieves the purpose of giving full play to the ternary materials of different compositions, but in the course of the test, it is further found that the active materials coated by layers are due to the different materials in the charging and discharging process. The volume expansion rate is different, so the expansion coefficient between the layers is different, resulting in a decrease in cycle performance. Therefore, based on the above problems, the following cathode preparation method is further proposed