Tunable oxygen deficient in MoO3-x/MoO2 heterostructure for enhanced lithium storage properties

MoO3 is a kind of promising anode material for lithium-ion batteries (LIBs) owing to its high specific capacity and layered structure. However, the intrinsically sluggish redox kinetics results in poor rate and Li-ions storage capability. Oxygen vacancies (OVs) are considered to be effective in enhancing the conductivity and expanding the lattice distance of metal oxides. Here we report a strategy to synergize the merits of OVs and heterostructure by simply controlling the pH value of the reaction environment based on the reduction of ethanol. The tunable OVs concentration not only alters the bandgap but also expands the lattice spacing of MoO3-x and eventually generates the MoO3-x/MoO2 heterojunction. The built-in electric field results from OVs and heterojunction drive high reaction kinetics, combing with the enlarged interlayer spacing, making MoO3-x/MoO2 heterojunction a promising electrode in Li-ion batteries. As expected, the MoO3-x/MoO2 heterojunction exhibits a high specific capacity of 600 mA g(-1) at 0.1 A g(-1) and 400 mAh g(-1) at 1 A g(-1) with a high capacity retention of 61%. This strategy on oxygen vacancies paves the way to regulate the valence structure, lattice structure and even component of electrode materials, endows them desired features, and provides an alternative way to meet the demands in energy storage systems.