Dynamics of proton intercalation into Al3+-doped vanadium oxide in an aqueous magnesium-containing electrolyte

[Display omitted] •Al0.072V2O5 was synthesized by hydrothermal method.•Al0.072V2O5 shows stable performance in aqueous Mg-ion containing electrolyte.•Direct monitoring of cyclic change of pH values near Al0.072V2O5 cathode surface.•The hybrid charge storage mechanism of Mg2+ and H+ co-intercalation is suggested. Al3+-doped vanadium oxide (AlxV2O5) with x = 0.072 was synthesized by hydrothermal method. The presence of Al3+ ions in the layered structure of AlxV2O5 agglomerated in the form of “nanoflowers” was confirmed. The mechanism of electrochemical intercalation processes in AlxV2O5 cathodes in Mg2+-containing aqueous electrolyte was studied. The dynamics of the near-electrode electrolyte pH during charge–discharge processes was investigated by in situ pH measurements. The cyclic evolution of the electrolyte pH during the charge–discharge process suggests the direct involvement of hydrogen ions in the intercalation processes along with Mg2+-intercalation.