Preparation and electrochemical properties of Li2MoO3/C composites for rechargeable Li-ion batteries

Abstract

Layered Li₂MoO₃ is a potential candidate for a high-capacity positive electrode material for Li-ion batteries because of its excess lithium composition. However, the difficulty of single-phase preparation and its insulating nature are drawbacks for its application in lithium-ion batteries. A small quantity of acetylene black added in the starting material solves these drawbacks, i.e. the formation of impurity phases and the low conductivity. As a result, a Li₂MoO₃/C composite is successfully synthesized with the simple addition of acetylene black. Since the electronic conductivity of the composite is enhanced to more than 1000 times higher than that of bare Li₂MoO₃, the Li₂MoO₃/C composite delivers approximately 230 mA h g⁻¹ of initial discharge capacity in a voltage range of 1.5–4.3 V, while carbon-free Li₂MoO₃ shows only 110 mA h g⁻¹ of initial discharge capacity. During the initial lithium extraction and insertion, a partial transformation from a layered into a cation-disordered cubic structure is evidenced in the Li₂MoO₃/C composite electrode by X-ray diffraction.