Facile strategies to utilize FeSO4·7H2O waste slag for LiFePO4/C cathode with high performances

Abstract This study proposes two economic and environmental-friendly strategies to synthesize LiFePO 4 /C composite as cathode for lithium ion battery, by utilizing the byproduct of industrial TiO 2 , FeSO 4 ·7H 2 O waste slag, as one raw material. And divalent ferrous phosphate, Fe 3 (PO 4 ) 2 ·8H 2 O, plays a significant role of intermediate. By wet-mill and spray-drying method, monodisperse LiFePO 4 /C microspheres are obtained with a hierarchically porous structure. And the micro-spherical LiFePO 4 /C composite shows an excellent rate capability and cycle performance, with initial discharge capacities of 153.6, 132.9, and 115.1 mAh g −1 at 0.5 C, 5 C and 20 C, respectively. The capacity retention remains at 88.4% even after 1000 cycles at the high rate of 10 C. By an improved conventional method, a hybrid-crystalline precursor is prepared and the submicron-sized LiFePO 4 /C composite also exhibits comparable rate capability. Therefore, the FeSO 4 ·7H 2 O waste slag can partially or totally replace analytically pure ones to manufacture high performance LiFePO 4 , which is a low-cost and promising option.