The Use of Reduced Cost and Purity Precursors in the Melt Preparation of LiFePO4

Different synthetic routes, such as solid state, sol-gel, hydrothermal, co-precipitation, and microwave preparations, have been used for preparing LiFePO₄; (LFP) a key cathode material in lithium-ion battery applications. Usually it is necessary to use costly precursors with a high purity, such as FePO₄ or FeC₂O₄, for the synthesis of LFP. In most methods secondary phases formed during synthesis, give rise to lower subsequent electrochemical capacities in the final product. The melt synthesis is an alternative, rapid and low-cost process proposed by Gauthier et al., and can be a promising method for the large scale preparation of LFP. This process combines ideal-liquid phase reaction with short dwell times and fast reaction kinetics in a reducing atmosphere. Our team made an effort to reduce the high manufacturing cost of LFP by using a melt synthesis, enabling the utilisation of lower purity and lower cost raw materials; namely iron ore concentrate as a source of iron. In this work, different synthesis conditions (such as iron precursors, stoichiometric ratios, and solidification processes) are optimized to obtain a low cost carbon-coated LFP with a high purity and excellent electrochemical properties.