A Study of Mg Intercalation Mechanism of a Prospective Mg Full Cell Design

A preliminary prospective full cell design composed of V₂O₅·xH₂O as cathode with a Mg metal as anode is constructed where insertion and de-insertion of magnesium into V₂O₅·xH₂O is fully reversible. An in-depth understanding of the Mg intercalation mechanism is investigated by pair distribution function analysis, x-ray absorption near edge structure (XANES) and 25Mg magic angle spinning (MAS NMR) spectroscopy. Interestingly, Mg intercalation results in the formation of multiple phases with different interlayer spacings. Our findings showed that the interlayer spacing of V₂O₅·xH₂O contracts upon Mg intercalation and expands for de-intercalation. An in-depth MAS NMR reveals the existence of two magnesium environments and more interestingly, magnesium intercalation induced a more well-defined Mg-O environment.