A novel method for multi-doped LiFePO4/C preparation with phosphating sludge

Multi-doped LiFePO4/C is prepared using phosphating sludge as raw material. A flexible acid pickling method is employed to regulate the composition of phosphating sludge. Quantitative analysis indicates that the superfluous Zn and Ca have been removed efficaciously from phosphating sludge, and the powder product is suitable to prepare LiFePO4 precursor. Carbothermal reduction method is employed to synthetize LiFePO4/C. XRD and Rietveld refinement show that the APPS-LiFePO4/C is a pure phase and its unit cell volume has been reduced along a- and b-axis by the multielement doping. FE-SEM images present that most of the APPS-LiFePO4/C particles are in size between 200 and 400 nm. The specific capacity and cyclability of obtained mutli-doped LiFePO4/C are both better than those of the R-LiFePO4/C prepared with chemical reagent at the current density of 0.1, 0.5, 1.0 and 2.0 C, respectively.