Preparation method of porous lithium iron phosphate powder

Abstract

Disclosed is a preparation method of porous lithium iron phosphate powder. The preparation method includes dissolving trivalent iron salt into water and preparing solution; adding alkali liquor in the boiling state to obtain Fe(OH)3 nano particles, dispersing the Fe(OH)3 nano particles in the water after washing, forming iron sesquioxide colloid with stirring intensively; adding a water-soluble lithium source, a phosphorus source, a carbon source and doped ion compound into the iron sesquioxide colloid, intensively stirring to form colloid-shaped mixed pulp uniformly molecularly mixed; drying the pulp by mist and obtaining spherical lithium iron phosphate precursor with average grain diameter ranging from D50=2-3 micrometers; sintering the precursor in the inertia atmosphere at the temperature of 300-500 DEG C for 2-10 hours, and sintering the precursor again at the temperature of 500-800 DEG C for 2-12 hours and obtaining carbon-coated spherical porous lithium iron phosphate powder with average grain diameter of D50=2-3 micrometers.

Description

technical field [0001] The invention relates to lithium iron phosphate powder, a preparation method of a positive electrode material of a lithium ion battery. Background technique Lithium iron phosphate batteries have the advantages of rich raw materials, environmental friendliness, high potential and theoretical specific capacity, stable discharge voltage, good cycle performance, high safety and thermal stability, etc., and are considered to be the most widely used lithium-ion power batteries , has a broad market prospect in the fields of electric vehicles, hybrid electric vehicles, electric tools, energy storage power stations and other fields. However, the ionic conductivity and electronic conductivity of lithium iron phosphate are both low, so it is only suitable for charging and discharging at low current density. application of materials. At home and abroad, a large number of researches on the modification of lithium iron phosphate have been carried out to improve...

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Problems solved by technology

However, the preparation process of lithium iron phosphate described in this patent has the following deficiencies: First, the preparation of Fe(OH) is not removed during the preparation process. 3 SO introduced during colloid 4 2- , NO 3 - , Cl - and other anionic impurities, these anionic impurities have a great impact on the electrochemical performance of the final product; second, the vacuum drying method used is likely to cause segregation of the precursor composition, which eventually leads to uneven carbon coating and low product purity

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