Regulating the Intermediate Process of Zinc-Bismuth Batteries by Iodide Ions

Neutral aqueous electrolytes are more compatible withthe anodeof zinc metal batteries than alkaline electrolytes. Previous reportshave shown that Zn||Bi2O3 batteries with mildelectrolytes have not been able to function effectively, though Bi2O3 stands out as a promising cathode material witha low cost and potentially high capacity. Herein, iodide ions areintroduced as a multifunctional electrolyte additive, allowing fora reversible multielectron conversion reaction of Bi(0) & LRARR; Bi(III)in mild aqueous electrolyte. Iodide ions significantly alter the intermediatereaction steps, leading to a kinetically favorable mechanism throughcoordination with Bi3+ to continuously refresh and activatethe interface. The resulting secondary neutral Zn||Bi2O3 battery delivers a high specific capacity (1960 mAh cm(-3)), exceptional rate performance, and remarkable cyclingstability (1225 mAh cm(-3) at 10 A g(-1), retaining 85% after 1500 cycles) with the conversion efficiencyclose to 100% per cycle. This work provides an energetic perspectivefor reversible battery chemistry.