Synthesis of porous MoV₂O₈ nanosheets as anode material for superior lithium storage

Abstract

Vanadium-based mixed oxides are promising for high-energy-density lithium-ion batteries (LIBs) due to their abundant oxidation states, complex chemical compositions and synergistic effects, but the large volume change upon lithiation/delithiation limits the electrochemical properties. Two-dimensional nanostructures have great potential in the development of electrode materials by promoting the ion transport and alleviating the volume change. Herein, porous MoV₂O₈ nanosheets are synthesized via a solvothermal process followed by thermal treatment without using any surfactants. Benefiting from the nanosheet structure with large surface area and abundant pores, the MoV₂O₈ electrode exhibits impressive lithium storage properties with superior rate performance and prolonged cyclability. Superior reversible capacities of 1396 and 570 mA h g⁻¹ can be maintained after 120 cycles at 200 mA g⁻¹ and after 1000 cycles at 10 A g⁻¹, respectively. Furthermore, the lithium storage mechanism of the MoV₂O₈ nanosheets was investigated by in-situ X-ray diffraction, ex-situ X-ray diffraction and X-ray photoelectron spectroscopy measurements, which confirms the synergistic effects of Mo and V upon lithiation/delithiation. In addition, a full cell consisting of the MoV₂O₈ nanosheets and commercial LiFePO₄ exhibited good electrochemical performance, demonstrating the great potential of the MoV₂O₈ nanosheets as an anode material for LIBs.