Superior lithium storage performance in MoO3 by synergistic effects: Oxygen vacancies and nanostructures

Abstract

The process of oxygen vacancy generation in MoO 3 using electron-proton co-doping strategy is investigated by DFT calculation. On the one hand, oxygen vacancies intrinsically improve the semiconductor properties of MoO 3 . On the other hand, the nanostructure externally improves the massive expansion of MoO 3 during the lithiation process. Dual synergistic effects ensure high capacity and long cycle stability. • DFT is used to calculate the products of electron-proton co-doping. • The dual synergistic effect of intrinsic and extrinsic standpoints is considered. • Minerals are used directly as electrode materials. • Methods to improve the electrochemical performance of TMOs is provided. Molybdenum trioxide (MoO 3 ) has recently attracted wide attention as a typical conversion-type anode of Li-ion batteries (LIBs). Nevertheless, the inferior intrinsic conductivity and rapid capacity fading during charge/discharge process seriously limit large-scale commercial application of MoO 3 . Herein, the density function theory (DFT) calculations show that electron-proton co-doping preferentially bonds symmetric oxygen to form unstable H x MoO 3 . When the -OH- group in H x MoO 3 is released into the solution in the form of H 2 O, it is going to form MoO 3− x with lower binding energy. By the means of both electron-proton co-doping and high-energy nanosizing, oxygen vacancies and nanoflower structure are introduced into MoO 3 to accelerate the ion and electronic diffusion/transport kinetics. Benefitting from the promotion of ion diffusion kinetics related to nanostructures, as well as both the augmentation of active sites and the improvement of electrical conductivity induced by oxygen vacancies, the MoO 3− x /nanoflower structures show excellent lithium-ion storage performance. The prepared specimen has a high lithium-ion storage capacity of 1261 mA h g −1 at 0.1 A g −1 and cyclic stability (450 cycle), remarkably higher than those of previously reported MoO 3 -based anode materials.