Method for preparing barium-activated lithium iron phosphate cathode material

Abstract

The invention relates to a method for preparing a barium-activated lithium iron phosphate cathode material. The method is characterized by comprising the steps of: mixing raw materials of a lithium source, a ferrum source, a phosphate source and a barium source according to the proportion of Li:Ba:Fe:P of 1mol:(0.0003mol):1mol:1mol, performing high-speed ball-milling (at the rotating speed of 200r / min) on the mixed raw materials in an absolute ethyl alcohol (AR) medium and drying at 105-120 DEG C to obtain a precursor; and placing the dried precursor in a high-temperature furnace and calcining for 24h at a high temperature of 500-750DEG C in an ordinary pure nitrogen atmosphere to obtain the barium-activated lithium iron phosphate cathode material. The chemical general formula of the material can be represented as Li Ba FePO4. As a bit of substituent barium is doped, the appearance and the particle size of the product are favorably controlled, and a stable lithium iron phosphate compound is obtained. Barium ions replace lithium ions in an occupation manner, the crystal lattice of the compound is activated, the diffusion coefficient of the lithium ions is increased, and the first discharge capacity of the cathode material reaches 145.52mAh / g. The potential of a charge-discharge platform of the cathode material is about 3.5V compared with that of a lithium electrode, the initial discharge capacity exceeds 162mAh / g, and the capacity is attenuated by about 3.2% after 100 times of charge-discharge circles. Compared with the undoped LiFePO4 contrast embodiment, the cathode material has greatly increased specific capacity and cyclical stability. As the price of barium is more than 100 times lower than the price of lithium, the production cost can be reduced by more than 10 times.

Description

technical field [0001] The invention relates to a method for preparing a barium-activated lithium iron phosphate positive electrode material, which belongs to a method for preparing a lithium battery positive electrode material, and in particular to a method for preparing a lithium iron phosphate battery positive electrode material. Background technique [0002] At present, the research status of lithium iron phosphate doping modification: lithium iron phosphate LiFePO4 is non-toxic, environmentally friendly, high in safety, rich in raw materials, high in specific capacity, stable in cycle performance, and low in price. The stable discharge platform with a theoretical capacity of 3.5V, the lithium iron phosphate material has high energy density, low price, and excellent safety, and is especially suitable for power batteries. But it has a higher resistivity. Due to lithium iron phosphate, the kinetics of LiFePO4 is not good at room temperature, and the rate performance is ex...

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Problems solved by technology

[0005] At present, there is a consensus that lithium iron phosphate has the advantages of good safety, no pollution, stable cycle performance, high specific capacity and low price, but it also has poor conductivity and the disadvantage of lower tap density