Co-activated Conversion Reaction of MoO2:CoMoO3 as a Negative Electrode Material for Lithium-Ion Batteries

摘要

Extensive studies to develop high-capacity electrodes have been conducted worldwide to meet the urgent demand for next-generation lithium-ion batteries. In this work, we demonstrated a novel strategy to alter the lithiation mechanism of the transition metal oxide to increase the reversible capacity of the electrode material. A representative insertion-type negative electrode material, MoO_(2), was modified by introducing a heterogeneous element (Co) to synthesize the solid solution of CoO and MoO_(2) (CoMoO_(3)). CoMoO_(3) exhibited a notably improved reversible capacity of 860 mA h g~(–1), attributed to the conversion reaction, in contrast to MoO_(2) that delivers 310 mA h g~(–1), as it is limited by the insertion reaction. X-ray absorption spectroscopy and X-ray diffraction demonstrated that CoO is converted to Co and Li_(2)O, amorphizing the host structure, whereas the conversion of MoO_(2) takes place subsequently. Furthermore, the superior initial Coulombic efficiency of CoMoO_(3) (84.4%) to that of typical conversion materials is attributed to the highly conductive Co and MoO_(2), which reinforce the electronic conductivity of the active particles. The results obtained from this study provide significant insights to explore high capacity metal oxides for the advanced lithium-ion batteries.