Preparation method of bismuth and barium activated lithium iron phosphate as cathode material

Abstract

The invention discloses a preparation method of bismuth and barium activated lithium iron phosphate as a cathode material. The preparation method comprises the steps of: mixing raw materials including a lithium source, a bismuth source, a barium source, an iron source and a phosphate source according to the proportion of 1mol:(0.00002-0.00005)mol:(0.0003-0.003)mol:1mol:1mol; then, performing high-speed ball milling at the rotation speed of 200r / minm for 20h in an absolute ethyl alcohol medium; drying at 105-120 DEG C to obtain a precursor; placing the precursor obtained through drying in a high-temperature furnace; and calcinating for 24h at the high temperature of 500-750 DEG C in a common pure nitrogen atmosphere to obtain the bismuth and barium activated lithium iron phosphate as the cathode material. Because a small amount of substitutive bismuth and barium are doped, the shape and the particle size of a product are favorably controlled to obtain a stable lithium iron phosphate compound, of which the crystal lattice is activated, the lithium ion diffusion coefficient is increased, and the initial discharge capacity of the obtained cathode material reaches 160.52mAh / g; a charge-discharge platform of the cathode material is about 3.5V relative to a lithium electrode potential, the initial discharge capacity exceeds 168mAh / g, and the capacity is attenuated by about 1.2% after 100 times of charge-discharge cycles; and compared with a control embodiment, namely undoped LiFePO4, the cathode material is greatly improved in specific capacity and cyclic stability.

Description

technical field [0001] The method for preparing a bismuth- and barium-activated lithium iron phosphate positive electrode material of the invention belongs to a method for preparing a lithium battery positive electrode material, and in particular relates to a preparation method for 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 perform...

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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