Simply prepared Mg-V-O as potential cathode material for rechargeable aqueous magnesium ion batteries

Abstract

Although today widely used in electronic devices and electric vehicles, lithium ion batteries encounter problem of future application, resulting from limited Li resources, relatively high costs and operational safety problems. Rechargeable magnesium batteries as a potential alternative to the Li-ion ones stand out because of their high theoretical specific capacity, high abundance of Mg resources, atmospheric stability, safety of handling, eco friendliness and low cost. Layered materials including oxides, sulphides and selenides are promising candidates for host materials for Mg2+ storage in rechargeable magnesium batteries. Slow migration of Mg2+ in the layered oxides, ascribed to the strong interaction between Mg and neighbouring O atoms, inspires researchers to look for the ways of improving their electrochemical performance. In this work, Mg-V-O material was synthesized by simple precipitation method, followed by thermal annealing. The obtained material is single-phase material consisted of MgV2O6 phase, according to the results of XRD, FTIR and Raman spectroscopy. Electrochemical test by cyclic voltammetry in aqueous solution revealed redox peaks corresponding to the insertion/deinsertion of Mg2+ ions into/from the material, but with poor current densities. In order to improve the electrochemical performance of the simply prepared Mg-V-O material, carbon was integrated with the Mg-V-O by sucrose-assisted thermal treatment. Although composed of several phases, the obtained Mg-V-O/C material exhibited around 40 times higher maximal specific current values of Mg2+ insertion/deinsertion than the Mg-V-O. Also, the electrochemical performance of the Mg-VO/ C for the insertion/deinsertion of Mg2+ ions was better than those of Al3+ and Li+ ions.