Effects of I3− Electrolyte Additive on the Electrochemical Performance of Zn Anodes and Zn/MnO2 Batteries

Abstract While delivering the highest energy density among low‐cost aqueous batteries, the practical implement of rechargeable Zn‐ion batteries (ZIBs) is still seriously restricted by the dynamic parasitic reactions on the metallic Zn anodes including dendrite growth, H 2 evolution and corrosion reactions. Modulating electrolyte is identified as a facile and effective approach to restrain these detrimental processes by various chemical mechanisms. Herein, we report a new strategy to improve the performance of Zn anodes and ZIBs by simply adding I 3 − species into the electrolytes. The I 3 − can react with the surface Zn and passivate the growth hotspots of Zn dendrites, prolonging the cycling lifetime of the electrodes. As a competitive reaction, it can also suppress the H 2 O‐derived corrosion and H 2 evolution process. The I 3 − is regenerable by oxidizing reactions on cathode surface, and can therefore long‐term persist its beneficial effects in ZIBs, as demonstrated in the classic Zn/MnO 2 battery. However, the I 3 − additive seems failed in evolving into a dense interfacial protective layer, and may be useful as a supplementary measure to prevent shorting failure of Zn‐based batteries.