Synthesis and electrochemical properties of metals-doped LiFePO 4 prepared from the FeSO 4·7H 2O waste slag

Abstract

FePO 4· xH 2O precursor was synthesized by using raw materials, FeSO 4·7H 2O waste slag and H 3PO 4, without any purifying process. Crystalline metals-doped LiFePO 4 was prepared by heating an amorphous LiFePO 4. The amorphous LiFePO 4 was obtained via a novel ambient temperature reduction method, using the as-prepared FePO 4· xH 2O, oxalic acid and Li 2CO 3 as raw materials. ICP analysis confirms that a small amount of Ti, Al and Ca deposited in precursor. XRD and Rietveld-refined results show that the metals-doped LiFePO 4 is single olivine-type phase and well crystallized, Ti atoms occupy Li (M1) site, resulting in the formation of cation-deficient solid solution. From SEM and corresponding elemental mapping images, it could be found that the particle size of LiFePO 4 is about 200–500 nm, and the distribution of elements (Fe, P and Ti) is homogeneous. The electrochemical performance of LiFePO 4 cathode was evaluated by galvanostatic charge/discharge test. The results indicate that the metals-doped LiFePO 4, prepared from the FeSO 4·7H 2O waste slag, delivers a capacity of 161, 153, 145, 134 and 112 mAh g −1 at 0.1 C, 0.5 C, 1 C, 2 C and 5 C rate, respectively, and shows an excellent cycling performance at moderate current rates (up to 2 C).