Study of LiFePO4 synthesized using a molten method with varying stoichiometries

Abstract

The synthesis of LiFePO4 from a melt cast of Li2CO3, FePO4, and carbon precursors at 1,000 °C was recently reported. The results indicate that it could be a competitive technique for the large-scale production of LiFePO4. This paper focuses on particle size reduction and non-stoichiometric synthesis of LiFePO4. The particles size was reduced using a planetary mill that is available in most research laboratories where the milling time and milling media were varied to obtain the best electrochemical results. In addition, the electrochemical performance of LiFePO4 products synthesized from $$ {\hbox{FeP}}{{\hbox{O}}_4} + x{/2}\,{\hbox{L}}{{\hbox{i}}_2}{\hbox{C}}{{\hbox{O}}_3} + {\hbox{C}} $$ (sequentially varying the amount of x) at 1,000 °C has also been measured. The stoichiometric LiFePO4 product shows the best capacity, while the off-stoichiometric material demonstrates different levels of impurities that have an effect on the performance of the material. The results indicate that adequate capacity at low discharge rates can be obtained using standard milling techniques, but, in order to obtain material from a melt cast synthesis that provides higher performance at faster discharge rates, a further particle size reduction will be required.