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

Abstract

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.