Effect of Antisolvent Additives in Aqueous Zinc Sulfate Electrolytes for Zinc Metal Anodes: The Case of Acetonitrile

Aqueous zinc-ion batteries (ZIBs) employing zinc metal anodes are gaining traction as batteries for moderate to long duration energy storage at scale. However, corrosion of the zinc metal anode through reaction with water limits battery efficiency. Much research in the past few years has focused on additives that decrease hydrogen evolution, but the precise mechanisms by which this takes place are often understudied and remain unclear. In this work, we study the role of an acetonitrile antisolvent additive in improving the performance of aqueous ZnSO₄ electrolytes using experimental and computational techniques. We demonstrate that acetonitrile actively modifies the interfacial chemistry during Zn metal plating, which results in improved performance of acetonitrile-containing electrolytes. Collectively, this work demonstrates the effectiveness of solvent additive systems in battery performance and durability and provides a new framework for future efforts to optimize ion transport and performance in ZIBs.