Lithium ion secondary battery and positive electrode active material thereof

Abstract

The invention discloses a positive electrode active material of a lithium-ion secondary battery, which structurally comprises three layers, the three layers are respectively a matrix positioned on a center, a co-crystallizing grid layer covering the matrix and a covering layer covering the co-crystallizing grid layer, wherein the matrix is made from metallic oxide containing lithium, the co-crystallizing grid layer is made of the matrix material mixed with transition metal, and the material of the covering layer is metal oxide ZOi, phosphate Z (PO4)j or fluoride ZFk. Compared with prior art, the positive electrode active material of the lithium-ion secondary battery adopts a three-layer structural material in design, the covering layer on the outermost layer is made of stable ceramic material, the direct effect of electrolyte and active material can be effectively improved, the co-crystallizing grid layer and the matrix material are in eutectic cladding, so as to enable the transportation of Li+ to be free from blockage. Therefore, the purpose of expanding positive electrode active material charging to end voltage is achieved.

Description

technical field [0001] The invention relates to a lithium-ion secondary battery, in particular to a lithium-ion secondary battery and its positive electrode active material. Background technique [0002] In recent years, the miniaturization of mobile electronic terminals, the development of power vehicle batteries and energy storage batteries have put forward higher and higher requirements for the energy density of lithium-ion secondary batteries. People have adopted the following methods to improve the energy density of lithium-ion secondary batteries: first, select positive / negative active material materials with higher mass specific capacity; second, select positive active materials with higher voltage platform; third 1. Reduce the mass ratio of inactive substances to active substances; 4. Directly increase the charge cut-off potential of the positive electrode without changing the negative electrode. The fourth way is the most direct, effective and fastest way, because ...

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Problems solved by technology

Furthermore, it can be seen from the accompanying drawings of the disclosed description that there are relatively obvious gaps between the layers of the material disclosed in the invention, which will make the charging and discharging process of the battery difficult, that is, the lithium ion intercalation and extraction process in the material Need to cross multiple "chasms", resulting in unsatisfactory power performance

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