Electrospun V2MoO8 as a cathode material for rechargeable batteries with Mg metal anode

With the increasing global demand for large-scale electrical energy storage, rechargeable Mg-based batteries are preferable due to their substantial prospective benefits in terms of raw abundance, theoretical capacity, and operational safety. Herein, we demonstrate for the first time V2MoO8 synthesized by a facile electrospinning method as a cathode material for rechargeable magnesium batteries with the electrolytes containing Mg2+ or Mg2+/Li+ ions. SEM and HRTEM indicate that the V2MoO8 sample presents wedged-shaped cuboid, 300-500 nm (thickness) x 4-6 mu m (length) and its monoclinic phase structure provides a interlayer distance of 4.20 angstrom. As cathode material, V2MoO8 is discharged/charged in a specially self-designed mould battery using Mg metal anode at current densities from 20 to 500 mA g(-1). It delivers a high initial discharge capacity of 312 mA h g(-1) with the initial coulombic efficiency of 87.2% at 20 mA g(-1) in 0.4 M (PhMgCl)(2)-AlCl3/1.0 M LiCl/THF electrolyte and presents good cycling and rate performance. XPS analysis reveals that both Mg2+ and Li+ ions take part in the cathode intercalation reaction, along with the valence changes of Mo/V ions. Additionally, a reversible capacity of ca. 210 mA h g(-1) is obtained in Mg2+ electrolyte with the 1st cycle efficiency of 94% at 60 degrees C. The poor capacity retention is partially attributed to the irreversible phase change to amorphous state of V2MoO8.