A High-Energy Tellurium Redox-Amphoteric Conversion Cathode Chemistry for Aqueous Zinc Batteries.

Rechargeable aqueous zinc batteries are potential candidates for sustainable energy storage systems at a grid scale, owing to their high safety and low cost. However, the existing cathode chemistries exhibit restricted energy density, which hinders their extensive applications. Here, a tellurium redox-amphoteric conversion cathode chemistry is presented for aqueous zinc batteries, which delivers a specific capacity of 1223.9 mAh g and a high energy density of 1028.0 Wh kg . A highly concentrated electrolyte (30 mol kg ZnCl) is revealed crucial for initiating the Te redox-amphoteric conversion as it suppresses the HO reactivity and inhibits undesirable hydrolysis of the Te product. By carrying out multiple operando/ex situ characterizations, the reversible six-electron Te/Te/Te conversion with TeCl is identified as the fully charged product and ZnTe as the fully discharged product. This finding not only enriches the conversion-type battery chemistries but also establishes a critical step in exploring redox-amphoteric materials for aqueous zinc batteries and beyond.