Kinetically Enhanced Reaction Pathway to Form Highly Crystalline Layered LiCoO at Low Temperatures Below 300 °C.

Layered LiCoO is usually synthesized after a prolonged sintering process at high temperatures (≥800 °C) for 10-20 h. This study developed a "hydroflux process" to obtain highly crystalline and layered LiCoO at a low temperature of 300 °C within 30 min. Molten mixed hydroxide-containing water molecules significantly accelerated the formation of LiCoO, which showed a highly reversible capacity of 120 mAh g without postannealing. The reaction mechanism study showed fast growth of LiCoO crystals, suggesting that the excess molten hydroxides containing water dissolve the cobalt species of HCoO. Consequently, the accelerated LiCoO formation suppresses the competing reaction of CoO formation, leading to spinel LiCoO formation at low temperatures. Excess water in the starting materials further accelerated the crystal growth of LiCoO, forming large particles (>1 μm). Moreover, the layered LiCoO began to form at 150 °C. This study is the first experimental demonstration that proves the thermodynamic stability of layered LiCoO at low temperatures (150-300 °C) under ambient pressure. This novel process offers significant energy savings in the production process of LiCoO and other ceramics materials.