Melt Casting LiFePO[sub 4]

A melt casting process to make an electrochemically active Li Fe P O 4 cathode material was explored. The melting of carbon-coated Li Fe P O 4 powder at 1000 ° C followed by its cooling leads to a high purity Li Fe P O 4 material with excellent crystallinity and large crystals. From a detailed study on the melting of naturally occurring triphylite, elements such as Mg and Mn were easily incorporated into the olivine structure, while others such as Ca, Si, and Al were segregated into grain boundaries. Experiments also demonstrated that a variety of synthetic precursors can be used to make high purity Li Fe P O 4 materials through melt casting. The phase purity, crystallinity, and microstructures of the final product depend on the reducing conditions and the solidification process of the melt. The melt-casted material, after coarse grinding, shows good electrochemical activity.