High-rate and long-life VS2 cathodes for hybrid magnesium-based battery

Rechargeable magnesium-ion batteries (MIBs) have received growing attention due to high safety, low cost and high volumetric capacity. However, the sluggish Mg2+ kinetics in host materials because of high polarization of Mg2+ impede electrochemical performance of MIBs. To circumvent this problem, designing hybrid system composed of fast Li+ insertion cathode and safe Mg anode is a promising solution. Herein, graphene wrapped VS2 (VS2-GO) as cathode for hybrid magnesium-based batteries is presented for the first time. It delivers remarkable electrochemical performance with a high discharge capacity of 235 mA h g−1, ultra-high rate capability (129 mA h g−1 at 80 C) and long life (capacity of 146 mA h g−1 even after 10,000 cycles at 5 C). A reversible phase transition during the electrochemical process has been proved by ex-situ XRD, TEM, EDS mappings and XPS characterization. The impressive electrochemical performance demonstrates that the novel VS2 cathode has great potential for the development of the next generation safe and large-scale energy storage.