Method for eliminating residual lithium by lithium transition metal oxide and application thereof

Abstract

The invention provides a method for removing residual lithium from lithium transition metal oxide and application of the method. The method comprises the following steps: coating lithium transition metal oxide with a lithium absorbing agent, and carrying out heat treatment to form an amorphous surface layer; the amorphous surface layer is converted into a crystalline surface layer through crystallization treatment; the lithium absorbing agent comprises an amorphous substance. The method at least has the following beneficial effects that after the lithium transition metal oxide is coated with the amorphous substance, the amorphous substance has a very strong tendency of combining residual lithium under a heat treatment condition, the content of the residual lithium on the surface of the material can be greatly reduced, and meanwhile, the capacity reduction caused by lithium loss is avoided by absorbing the residual lithium on the surface; and then the amorphous state is converted into the crystalline state, so that crystal lattices are more complete, and the problem that the surface structure of the material is damaged due to energy release in the process of converting the amorphouslong-range disordered metastable state into the crystalline state and the resulting problem of battery attenuation are avoided; therefore, the electrochemical performance of the material is effectively ensured not to be reduced due to elimination of residual lithium on the surface.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to a method for eliminating residual lithium by a lithium transition metal oxide and an application thereof. Background technique [0002] Residual lithium usually refers to the residual soluble Li on the surface of lithium transition metal oxide powder materials 2 CO 3 And LiOH, the problem of residual lithium has a great impact on the battery. In the process of making rechargeable batteries and coating slurry, high residual lithium will make the slurry unstable, accelerate the gelation of the slurry, and weaken the uniformity of the battery. , and the high residual lithium on the surface of the positive electrode material is easy to react with the electrolyte to cause gas generation, which reduces the safety performance and cycle performance of the battery. There are two main sources of residual lithium on the surface of lithium transition metal oxide powders: first, d...

AI Technical Summary

Problems solved by technology

However, the water washing process will increase the cost of use. More importantly, the lithium transition metal oxide material is sensitive to moisture. If the drying time is too long, the contact time between the material and moisture will be too long, and the lattice lithium on the surface will be missing, resulting in the material Structural deterioration and serious performance attenuation

On this basis, the production and R&D personnel tried to add ethanol to remove water before drying. Although the performance problems caused by the subsequent drying time were reduced, the damage to the surface structure caused by water washing itself made the electrochemical performance worse. problem not solved

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