Recent Progress in Electrolyte Additives for Highly Reversible Zinc Anodes in Aqueous Zinc Batteries

Aqueous zinc batteries (AZBs) are one of the most promising large-scale energy storage devices by virtue of their high specific capacity, high degree of safety, non-toxicity, and significant economic benefits. However, Zn anodes in aqueous electrolyte suffer from zinc dendrites and side reactions, which lead to a low coulombic efficiency and short life cycle of the cell. Since electrolytes play a key role in the Zn plating/stripping process, versatile strategies have been developed for designing an electrolyte to handle these issues. Among these strategies, electrolyte additives are considered to be promising for practical application because of the advantages of low cost and simplicity. Moreover, the resulting electrolyte can maximally preserve the merits of the aqueous electrolyte. The availability and effectiveness of additives have been demonstrated by tens of research works. Up to now, it has been essential and timely to systematically overview the progress of electrolyte additives in mild acidic/neutral electrolytes. These additives are classified as metal ion additives, surfactant additives, SEI film-forming additives, and complexing additives, according to their functions and mechanisms. For each category of additives, their functional mechanisms, as well as the latest developments, are comprehensively elaborated. Finally, some perspectives into the future development of additives for advanced AZBs are presented.