High-Voltage Operation of a VO Cathode in a Concentrated Gel Polymer Electrolyte for High-Energy Aqueous Zinc Batteries.

Gel-type polymer electrolytes are very promising to replace liquid electrolytes, addressing the leakage concerns in batteries. In this work, we report a concentrated gel polymer electrolyte for aqueous zinc-metal batteries, which manifests superior Zn stripping/plating reversibility and electrolyte stability, combined with a promising electrochemical stability window and robust water-retention ability. Quasi-solid-state Zn/VO batteries employing such an electrolyte reach a specific energy of 326 W h kg at 20 mA g based on the cathode mass and a capacity retention of 93% over 600 cycles at 500 mA g. Moreover, the cell performs well in the 0-40 °C temperature range without significant capacity loss. These results represent important steps toward the development of high-energy aqueous zinc batteries.