Preparation method for magnesium/barium-activated lithium iron phosphate cathode material

Abstract

The invention discloses a preparation method for a magnesium / barium-activated lithium iron phosphate cathode material. The preparation method is characterized by comprising the following steps of: mixing raw materials which are a lithium source, an iron source, a phosphate group source, a magnesium source and a barium source in the molar ratio of 1:(0.002-0.005):(0.0003-0.003):1:1, ball-milling the mixture for 20h at the high rotating speed of 200r / mimn in an absolute ethanol medium, drying the mixture at 105 to 120 DEG C to obtain a precursor, arranging the dried precursor in a high-temperature furnace, and sintering the precursor for 24h at the high temperature of 500 to 750 DEG C to obtain the magnesium / barium-activated lithium iron phosphate cathode material. Due to the doping of a small amount of substitutional magnesium / barium, so control over the appearance and grain size of the product is facilitated, a stable lithium iron phosphate compound is obtained, the crystal lattice of the compound is activated, a lithium ion diffusion coefficient is increased and the first discharging capacity of a battery adopting the obtained material reaches 155.52mAh / g. The potential of a charging and discharging platform relative to a lithium electrode is about 3.5V, the initial discharging capacity of the battery exceeds 164mAh / g, and the capacity of the battery is attenuated by about 3.0 percent after 100 charging and discharging cycles. Compared with those of the control embodiment of undoped LiFePO4, the material prepared by the method has the advantages that: specific capacity and cyclical stability are relatively more improved. The cost of barium is a hundred times lower than that of lithium, so production cost can be decreased by over ten times.

Description

technical field [0001] The preparation method of magnesium and barium activated lithium iron phosphate cathode material of the present invention belongs to a preparation method of lithium battery cathode material, and in particular relates to a preparation method of lithium iron phosphate battery cathode 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 extremely poor. Resea...

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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