In Operando Synchrotron Diffraction and in Operando X-ray Absorption Spectroscopy Investigations of Orthorhombic VO Nanowires As Cathode Materials for Mg-Ion Batteries

Orthorhombic VO nanowires were successfully synthesized via a hydrothermal method. A cell-configuration system was built utilizing VO as the cathode and 1 M Mg(ClO) electrolyte within acetonitrile, together with Mg MoS ( x ≈ 2) as the anode to investigate the structural evolution and oxidation state and local structural changes of VO. The VO nanowires deliver an initial discharge/charge capacity of 103 mAh g/110 mAh g and the highest discharge capacity of 130 mAh g in the sixth cycle at C/20 rate in the cell-configuration system. In operando synchrotron diffraction and in operando X-ray absorption spectroscopy together with ex situ Raman and X-ray photoelectron spectroscopy reveal the reversibility of magnesium insertion/extraction and provide information on the crystal structure evolution and changes of the oxidation states during cycling.