Synergistic effect of multi-electron conversion and anion redox media chemistry for high-performance rechargeable aqueous Zn ion batteries

Abstract

A conversion-type BiOI cathode coupled with ZnI₂ additive as a redox medium is proposed to electrochemically store charge. By integrating the redox-targeting reactions interrelated with I⁻ and Bi³⁺ redox reactions, a volumetric capacity of 3589 mA h cm⁻³ and cycling life of 16 000 cycles with a capacity decay of 0.006 mA h g⁻¹ per cycle were reached. In-depth electrochemical mechanism research demonstrates that the high electrochemical performance results from the mutual reinforcing effects between Bi⁰/Bi³⁺ and I⁻/I₃⁻ conversion reactions.