Continuous hydrothermal synthesis of HT-LiCoO 2 in supercritical water

Abstract

A detailed investigation was made into the production of high temperature lithium cobalt oxide (HT-LiCoO 2) particles by continuous hydrothermal synthesis via the reaction of cobalt nitrate, lithium hydroxide, and hydrogen peroxide. The experiments were carried out in both subcritical and supercritical water, at temperatures ranging from 300 to 411 °C, with residence times less than 1 min in all instances. Although Co 3O 4 particles were synthesized in subcritical water at similar reaction conditions designed for comparison, well-ordered particles of HT-LiCoO 2 were obtained in supercritical water. In supercritical conditions, the variations in temperature and residence time did not have significant impacts on the average particle size, particle size distribution, or morphology of obtained HT-LiCoO 2. However, it was important to supply excessive lithium hydroxide and hydrogen peroxide in order to synthesize single-phased HT-LiCoO 2 particles without undesired by-products. The hydrothermal synthetic route for LiCoO 2, CoO, and Co 3O 4 in both subcritical and supercritical conditions was postulated.