Method for preparing anode material iron phosphate lithium of lithium ion battery

Abstract

The present invention relates to a method for producing LiFePO4 of positive pole of lithium ion battery. The invention is prominently characterized in that the method comprises three steps as follows: mixing the iron material, the lithium material and the phosphorus material uniformly to compound highly crystallized LiFePO4 in a high temperature first; adding a little diluted acid in the LiFePO4, after mixing and drying the processed LiFePO4 and conductive agent or pre-conductive agent, conducting ball mill for the mixture using a heavy ball; processing the mixture at a lower temperature and then the positive material LiFePO4 with excellent electrochemical performance can be gained. The gained LiFePO4 has favorable crystallinity and the electronic and the lithium ion conducting net is unique with excellent performance. The present invention uses cheap chemical product as raw material and the compounding art is simple thus is easy for producing on scale. The electrochemical character is favorable.

Description

technical field [0001] The invention relates to a preparation method of a cathode material of a lithium ion battery, in particular to a method for preparing lithium iron phosphate, an anode material of a lithium ion battery, by adopting high-temperature reaction, micro-acid dissolution, ball milling with heavy balls as a medium, and low-temperature lattice repair. Background technique [0002] Due to the advantages of high energy density, long service life, light weight, small self-discharge, no memory effect, and environmental friendliness, lithium-ion batteries have developed rapidly since their inception, and have become a popular choice for portable electronics such as mobile communications, notebook computers, and cameras. It is the preferred power source for products, and has been gradually developed as a power source for electric vehicles, defense equipment, etc., which also promotes the development of lithium-ion batteries in the direction of high energy, environmenta...

AI Technical Summary

Problems solved by technology

The advantage of the high-temperature method is that the process is simple and it is easy to realize industrialization, but the reactants are usually mixed unevenly, the product particles and grains are easy to grow, and the purity is not high. Therefore, the electrochemical performance is not high

The process of liquid phase co-deposition method is relatively complicated, Fe 2+ easily oxidized to Fe 3+ , need to add reducing agents such as ascorbic acid, the cost is high, and it is not conducive to industrialization

The sol-gel method can achieve molecular-level mixing of iron, phosphate and lithium, and it is also easy to achieve doping, and the properties of the obtained materials are also relatively ideal, but the process is relatively complicated and is not suitable for large-scale production

High-energy ball milling method (CN1255888C, Electrochem Solid State Lett 7 (2004) A522) mix metal iron powder, iron phosphate, lithium phosphate, doping element phosphate, conductive agent or conductive agent precursor in proportion, and place in an inert atmosphere. In a ball mill container, high-energy ball mill for 18-36 hours; the obtained ball mill product is put into a high-temperature furnace, and fired at a constant temperature of 450-750°C for 10-60min in an inert atmosphere such as nitrogen or argon, and the obtained lithium iron phosphate powder or doped phosphoric acid Lithium iron powder, the crystallinity of this positive electrode material is not very good, the conductivity of lithium ions is not good when charging and discharging at a high rate, and mass production cannot be realized

Images