A Rechargeable Aqueous Sodium Ion Battery

Abstract

We report a rechargeable sodium ion battery in aqueous environment with hydrophobic few layers graphene as the capacitive anode and hexacyanometallate as the insertion cathode. Owing to the lack of hydrophilic functionalities, sodium ion adsorption is selectively favoured over H+ ion adsorption at the hydrophobic anode/electrolyte interface without the complexity of widely encountered hydrogen ion insertion/H2 evolution. Hydrophobicity precludes chemical bond formation with sodium ions thereby improving reversibility and extended cyclability during charge discharge chemistry.