Lithium vanadium phosphate composite positive electrode material with porous foam and preparation method of lithium vanadium phosphate composite positive electrode material

Abstract

The invention discloses a preparation method of a lithium vanadium phosphate composite positive electrode material with porous foam. Biomass charcoal utilized by the invention is common biomass, is wide in source and reasonable in price and is green and environment friendly. The biomass charcoal is decomposed to amorphous carbon under a high temperature, the surface of lithium vanadium phosphate is coated, the conductivity of the lithium vanadium phosphate is improved, and moreover, the growth of lithium vanadium phosphate particles is also limited. The frog spawn-shaped lithium vanadium phosphate composite positive electrode material with a porous foam-core framework structure, formed in an oil bath pan, has the characteristics of many pores and hole-hole communication; and by the structure, an electrolyte can easily enter, the contact area of the electrolyte and the lithium vanadium phosphate composite positive electrode material with the porous foam is expanded, the lithium ion transmission path is greatly shortened, the lithium ion transmission efficiency is improved, so that favorable electrochemical performance is acquired. The preparation method is simple in process and relatively low in cost, and is easy to operate.

Description

technical field [0001] The invention relates to the field of preparation of electrochemical materials, in particular to a lithium vanadium phosphate composite cathode material with porous foam and a preparation method thereof. Background technique [0002] Since the advent of lithium-ion batteries in the 1990s, they have been considered ideal for high-capacity, high-power batteries because of their high energy density, good cycle performance, and charge protection capabilities. In lithium-ion batteries, a large amount of cathode material is used, which increases the production cost of lithium-ion batteries. At present, the substances used as cathode materials for lithium-ion batteries are mainly lithium-containing transition metal oxides, including layered LiMO (M=Co, Ni, Mn) and spinel-type LiMn. 2 o 4 . However, due to the price of these materials (LiCoO 2 ), safety (LiNiO 2 ), high temperature electrochemical performance (LiMn 2 o 4 ) and other reasons make them su...

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Problems solved by technology

However, carbon coating also has the following problems: firstly, it is difficult to uniformly distribute amorphous carbon among the particles, and it is difficult to guarantee the stability of product performance; secondly, the addition of amorphous carbon significantly reduces the tap density, which makes lithium vanadium phosphate The improvement of performance and the increase of tap density cannot be organically unified

When the method of doping with high-valent metal ions is used, the crystal structure of lithium vanadium phosphate is improved after the metal ions enter the crystal lattice, and the electronic conductivity is substantially improved, thereby improving its macroscopic electrochemical performance, but how to make the high-valent metal The accurate entry of ions into lithium or iron sites of lithium vanadium phosphate crystals is currently a difficult problem to control

[0005] Nowadays, a lot of biomass carbon such as cotton and straw are incinerated, fed to pigs or directly discarded as garbage, which not only causes a huge waste of resources, but also causes certain environmental pollution

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