Stabilization of VOPO 4 ·2H 2 O voltage and capacity retention in aqueous zinc batteries with a hydrogen bond regulator.

The transformation of polyanion cathodes into oxides in aqueous Zn batteries results in voltage decay. Herein, we uncover a polyanion dissolution and oxide re-electrodeposition process for this transformation. Accordingly, the dissolution is inhibited by reducing the water activity in the electrolyte with the hydrogen bond regulator of glucose (Glu). In the 4 m Zn(OTf) 2 /5.5 m Glu electrolyte, the VOPO 4 ·2H 2 O cathode maintains the redox reactions at a high voltage of 1.6 V/1.5 V with stable capacity retention during cycling at different rates. It also shows promising electrochemical activity and stability at temperatures down to -20 °C.