Long-range disordered MoO2 with rich oxygen vacancies for high-rate and durable lithium storage

Abstract

Transition metal oxides (TMOs) with high theoretical capacity hold great promise to replace the current graphite for lithium-ion battery, but they are limited by unsatisfactory high-rate and cycling stability. Herein, we demonstrated the mechanisms of oxygen vacancies and long-range disordered structure of MoO2-δ for high-rate and durable lithium storage, which aims at solving the trade-off between the capacity and high-rate and/or cycling stability on universal TMOs anodes. Series of experiments and density functional theory results demonstrate that oxygen vacancies in MoO2-δ could increase its electronic conductivity and optimize the Li-ion migration pathway as well as energy barrier for improving the Li-ion migration dynamics and high-rate performance, meanwhile the robust cycling stability of MoO2-δ anode is benefitted from the isotropic character of its long-range disordered structure and the corresponding derived ability to buffer the volume changes. As expected, the target MoO2-δ shows the high discharge capacity (1631.3 mA h g−1 at 0.2 A g−1), excellent rate capability (average capacities of 592.6 mAh g−1 at 8.0 A g−1), and robust cycling stability (1000 cycles without obvious capacity fading even at 5 A g−1). The proposed concept of oxygen vacancies and long-range disordered character of MoO2-δ in lithium storage could be extended to develop other high-performance energy storage materials.