A series of hydroxides NixMnxCo(1−2x)(OH)2 for x=0.00–0.50 were prepared. These hydroxides were used as the precursors in the synthesis of electrochemical active lithiated mixed metal oxides, LiNixMnxCo(1−2x)O2. The traditional co-precipitation method was used to synthesize the hydroxides and the effect of different post-synthetic treatments were tested. The solutions after co-precipitation of the hydroxides were heated under hydrothermal or microwave assisted hydrothermal conditions at 180°C. All samples were analyzed with X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements. We observed that the hydroxides undergo oxidation to an oxyhydroxide phase as the stoichiometry varies during their synthesis and with post-synthetic treatments. As the concentration of Ni and Mn increases in the sample, a mixture of both hydroxide and oxyhydroxide phases is obtained. SEM images demonstrate a sintering effect on the hydroxide particles after post-synthetic treatment, while XRD measurements on these samples show an increase in crystallinity and reduced turbostratic disorder. The oxides synthesized from these precursors demonstrate similar electrochemical performance with one another.

A melt casting process to make an electrochemically active LiFePO 4 cathode material was explored. The melting of carbon-coated LiFePO 4 powder at 1000°C followed by its cooling leads to a high purity LiFePO 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 LiFePO 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.