A lithium-rich positive electrode material/conductive flexible polymer composite material and its preparation method and application

Abstract

The invention provides a lithium-rich cathode material / conductive and flexible polymer composite material, a preparation method and an application, and relates to the field of cathode materials for lithium ion batteries. A flexible and conductive polymer and a lithium-rich cathode material are weighed, marking ink is prepared, a dispersion liquid of acetylene black as a conductive additive is added for mixing, a flexible polymer matrix framework with supporting protection capacity is constructed for the lithium-rich cathode material with a novel ink-jet printing technology and a mechanical dispersion technology, the framework can relieve mechanical stress caused by volume expansion, and meanwhile, the polymer has conductive performance, so that the electrochemical performance of the composite material can be improved. The adopted technologies are low in cost, simple and feasible, and industrial preparation is realized easily.

Description

technical field [0001] The present invention relates to the field of positive electrode materials for lithium ion batteries, in particular to flexible polymer modified lithium-rich positive electrode materials {xLi 2 MnO 3 ·(1-x)LiMO 2 The preparation method and application of (0<x<1)}. Background technique [0002] In order to meet the growing demand for miniaturization, diversity and variability of electronic products, flexible and wearable portable electronic products have become the trend of future development. Compared with traditional mobile electronic devices, flexible electronic devices can not only bend at will, but also realize specific functions by sensing changes such as stress. At present, the electrochemical devices powered by electronic products mainly include batteries and supercapacitors, which have high requirements on the flexible bending flexibility and mechanical deformation performance of the electrode materials. In order to meet the technical...

AI Technical Summary

Problems solved by technology

In recent years, lithium-rich cathode materials xLi 2 MnO 3 ·(1-x)LiMO 2 (M=Ni, Co, Mn, Fe) has attracted extensive attention because of its high specific capacity (~200mAh / g), excellent cycle capability, and new electrochemical charge-discharge mechanism, making its application of great potential. Potential, but lithium-rich materials are damaged by deformation stress during cycling, which restricts the bottleneck of its development

When it is used as an electrode material, there will be a huge volume expansion during the repeated intercalation and extraction of lithium ions, which will lead to a gradual decrease in the mechanical stability of the material, and the electrode material will gradually pulverize and fall off until it fails, the structure will be destroyed, and the contact resistance will increase. , the capacity decays rapidly, which seriously restricts its industrial application

[0003] When the internal stress caused by the constrained or uneven expansion of the electrode material exceeds the critical value, the electrode material is pulverized and fails

At the same time, the expansion causes the compression deformation of the diaphragm, resulting in a decrease in porosity and pore size, which in turn causes uneven migration of lithium ions and an increase in internal resistance.

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