Preparation of high performance LiFePO 4 /C by extracting iron element from iron tailings by concentrated sulfuric acid hot dip method

LiFePO 4 /C cathode materials are synthesized by carbothermal reduction process using FePO 4 as iron and phosphorus source, and starch as carbon source. The FePO 4 precursor was prepared by leaching iron tailings with concentrated sulfuric acid and then leaching with phosphoric acid and hydrogen peroxide. The morphology and structure of FePO 4 precursors prepared under different pH conditions were studied by using thermogravimetric-differential analysis (TG-DTA), infrared analysis (FTIR), x-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). The effect of the FePO 4 material on the properties of the synthesized LiFePO 4 cathode was investigated by charge and discharge cycles. On this basis, the effects of different molar ratios of C and LiFePO 4 on the performance of synthetic product LiFePO 4 /C were studied using starch as carbon source. The results show that the FePO 4 precursor prepared under the condition of pH 2 is the raw material, and the LiFePO 4 /C cathode material synthesized by adding 45% carbon has the best performance. The first cycle discharge capacity reached 142.6 mAh g −1 at a current density of 0.1 °C, reaching 83.9% of its theoretical capacity. This work proposes a novel and effective method to utilize the iron tailings.