Method for preparing carbon coated phosphates positive pole material by super critical fluid

Abstract

The invention discloses a process for preparing carbon-coated phosphate cathode material of a lithium ion battery through utilizing supercritical fluid, which comprises placing to-be-coated phosphate anode active material in a high-pressure stirred tank reactor, pumping supercritical fluid which dissolves with polymer solution into the reactor through a high-pressure pump, fully stirring under the condition of preset temperature and pressure to fully moisten the polymer solution and anode active substances, then fast spraying the mixed paste of supercritical fluid and active substances in an expansion separating chamber through nozzles, thereby making polymer solutes reach highly super-saturation state in a shorter time and grow on the surface of coated substances to form an even coating layer, and then conducting with high-temperature treatment under the non-oxidizing atmosphere to split off organic polymer material to form an even carbon-coated layer on the surface of the phosphate anode material.

Description

technical field [0001] The invention belongs to a method for modifying positive electrode materials of lithium ion batteries, in particular to a method for improving the conductivity of phosphate positive electrode active materials and preparing carbon-coated phosphate positive electrode materials for lithium ion batteries by using supercritical fluid. Background technique [0002] At present, great progress has been made in the negative electrode materials and electrolyte systems of lithium-ion batteries, while the development of positive electrode materials is relatively lagging behind, which seriously affects the powerization process of lithium-ion batteries. Its main performance is as follows: First, safety issues, the only commercial cathode material LiCoO 2 It is not stable enough, and it will decompose when overcharged and overheated, which may cause the battery to explode, which is especially prominent in power batteries; the second is the cost issue. The global coba...

AI Technical Summary

Problems solved by technology

[0007] In short, in the existing coating methods, due to the small particle size, large specific surface area and complex surface structure of lithium iron phosphate, uniform coating on the surface of lithium iron phosphate particles cannot be achieved.