Production method of lithium iron phosphate

Abstract

The invention discloses a production method of lithium iron phosphate with stable product quality and performances. The production method is characterized by comprising the following steps: adding raw materials into a ball mill for ball milling according to the proportion of iron phosphate to lithium carbonate to silver nitrate to deionized water of 1.0: (0.2-0.22): (0.001-0.002): (0.5-0.6), filtering, drying, reducing, calcining and crushing to prepare the nano-scale lithium iron phosphate taking silver oxide as a conductive agent. The method disclosed by the invention is simple and feasible, the synthesized lithium iron phosphate is pure phase and has good electrochemical performances and stable quality, the electrical gram capacity is above 150mAh / g and the tap density is 1.65g / cm<3>-1.70g / cm<3>. The lithium iron phosphate is assembled into a button cell by using a half-cell, charge-discharge testing is performed on the cell at the rate of 0.5C, the average discharge mass specific capacity is more than 150mAh / g, the cyclic coulombic efficiency is more than 95.0%, the charge constant current ratio is more than 98%, the discharge mean voltage is more than 3.4V, and the capacity retention rate after 100 cycles is more than 97.0%.

Description

technical field [0001] The invention relates to a preparation method of a positive electrode material of a lithium ion battery, in particular to a production method of lithium iron phosphate. Background technique [0002] In order to meet the society's requirements for power batteries, electric vehicles and various portable appliances, as well as new chemical power sources, the demand for lithium-ion batteries is increasing. At present, due to the toxicity of lithium cobaltate, the poor cycle performance and high temperature performance of lithium manganate, and the difficulty in the preparation of lithium nickelate, the application of these materials has been greatly restricted in the cathode materials of lithium ion batteries. Lithium iron phosphate with an olivine structure is an excellent new type of cathode material for lithium-ion batteries. Its theoretical specific capacity is up to 170mAh / g, and the charge and discharge voltage platform is about 3.4V. It has the adv...

AI Technical Summary

Problems solved by technology

However, the electrical conductivity of lithium iron phosphate cathode material is very poor, the electric capacity is less than 125mAh / g, and the stability of the produced battery is poor. Use a half-cell to assemble a button battery and conduct a charge-discharge test on the battery at a rate of 0.5C. , the average discharge mass specific capacity is less than 125mAh / g, which seriously restricts its large-scale application