Ternary chloride-free electrolyte design for highly efficient aqueous zinc-iodine batteries with four-electron conversion

A novel class of ternary hybrid aqueous electrolytes composed of betaine, nicotinamide, and zinc sulfate is designed to guarantee the reversible conversion of I-/I0/I+ redox pairs for zinc-iodine (Zn-I2) batteries to achieve four-electron transfer. Benefiting from the synergistic effect of ternary electrolytes, the Zn-I2 battery exhibits a high specific capacity of 355.5 mA h g-1. The designed ternary hybrid aqueous electrolyte assists Zn-I2 batteries achieve an enhanced capacity and energy performance compared with that of the conventional ZnSO4 electrolyte.