Anatase TiO₂ as an Anode Material for Rechargeable Aqueous Aluminum-Ion Batteries: Remarkable Graphene Induced Aluminum Ion Storage Phenomenon

Abstract

The electrochemical intercalation and extraction of Al 3+ ion in anatase TiO 2 is illustrated in various aqueous electrolytes in an attempt to demonstrate the viability of TiO 2 as an anode material for rechargeable aqueous aluminum-ion batteries. It is well understood that the primary barrier for diffusion of Al 3+ ion in TiO 2 is the poor electronic conductivity of TiO 2 . It is revealed that a small fraction of graphene (<2 wt %) could induce ultrafast diffusion of Al 3+ ion in TiO 2 . Estimation shows that graphene remarkably enhances the Al 3+ ion diffusion coefficient in TiO 2 by 672 times. Discharge capacities in the range of 33–50 mAhg –1 are obtained at a high current rate of 6.25Ag –1 for graphene incorporated TiO 2 . It is also seen that the nature of electrolytes critically influences the Al 3+ ion insertion phenomenon. The possibility of reversible crystal phase transition of TiO 2 to aluminium titanate due to Al 3+ ion intercalation-extraction is also demonstrated for the first time.