Ultrafine lithium cobalt oxide powder derived from a water-in-oil emulsion process

Lithium cobalt oxide (LiCoO2) is of interest for use in lithium ion batteries because of its high specific capacity, low self-discharge, and excellent cycle life. It is usually prepared by solid state reaction. Due to insufficient mixing and the low reactivity of the starting materials, calcination at 850-900 C for 10-20 h is required to synthesise LiCoO2; the prolonged calcination at high temperature leads to coarsening of the powder and the evaporation of Li species, which significantly impairs the product's electrochemical properties. The emulsion process has been shown to be effective for synthesising ultrafine ceramic powders and to increase the reactivity of the precursors. Ultrafine LiCoO2 powder with the Rbar3m structure was successfully prepared by a newly developed water-in-oil emulsion process. This emulsion process not only significantly shortens the reaction time for preparing LiCoO2, but also decreases the particle size of LiCoO2 to submicron order. The powder has good electrochemical properties, and can be used as a cathode in Li ion batteries. 23 refs.