A mini review: How to select electrolyte additives for better Zn anode electrochemistry?

Aqueous zinc metal battery (AZMB) is a promising energy storage system with multiple advantages due to its competitive cost, safety and capacity. However, AZMBs confront tough problems in the way to large-scale application, especially in terms of Zn anode, including Zn dendrite formation, hydrogen evolution reaction and corrosion. To overcome these obstacles, using electrolyte additives is considered as the most simple, economical and viable approach, thus articles about additives for the AZMBs' improvements are endless. To facilitate researchers to select additives in future research, which type and source of the additive compounds belong to, why to select such compounds, and how to select additives for better Zn anode electrochemistry are important. In this review, we categorize electrolyte additives from the insight of substance kinds (salt (ammonium salt, inorganic metal salt, organic metal salt), organic solvent, ionic liquid, acid (inorganic and organic acid), macromolecule (supramolecular material, polymer, saccharides and derivatives, protein), gas) and comprehensively tidy up their functions, properties, mechanisms and performances. In addition, leveraging successful precedents from diverse disciplines represents a novel and efficient approach. We also extract additives suitable for AZMBs from other fields, establishing the novel relations between their original application scenarios with AZMBs. This may spark researching inspirations from similar application scenarios or even completely different areas. Lastly, we propose an outlook on the future development of additives in AZMBs. We believe these aspects will lead the research direction of AZMBs' future additives and look forward to inspiring interdisciplinary achievements.