Preparation of LiCoO2 by Molten Salts on Li0.29La0.57TiO3 Solid Electrolyte and Electrochemical Performances of the All-solid-state Li Secondary Battery

An LiCoO2 (LCO) phase is prepared on a perovskite type Li0.29La0.57TiO3 (LLTO) solid electrolyte by heating mixed lithium salts of LiNO3 and LiCl with Co(NO3)2·6H2O at 700 °C for 1 h. The resultant LCO is evaluated as a positive electrode in an all-solid-state Li secondary battery. Liquid-phase sintering using molten salts has been effective for the formation of a favorable interface between oxides in which lithium ions migrate electrochemically with reversibility. The fracture surface revealed by field emission scanning electron microscopy observation shows that the microscopic texture of the LCO consists of a dense 1 to 2 µm thick layer closely attached to the solid electrolyte over a wide area, as well as LCO spherical particles with sizes of several micrometers. The former growth has superior electrochemical activity compared to the latter. Additionally, a preferential growth plane of the LCO on LLTO is analyzed by transmission electron microscopy and the process of formation with heating is described