Antisolvent addition has been widely studied in crystallization in the pharmaceutical industries by breaking the solvation balance of the original solution. Here we report as imilar antisolvent strategy to boost Zn reversibility via regulation of the electrolyte on amolecular level. By adding for example methanol into ZnSO 4 electrolyte,t he free water and coordinated water in Zn 2+ solvation sheath gradually interact with the antisolvent, whichm inimizes water activity and weakens Zn 2+ solvation. Concomitantly,d endrite-free Zn deposition occurs via change in the deposition orientation, as evidenced by in situ optical microscopy. Zn reversibility is significantly boosted in antisolvent electrolyte of 50 %m ethanol by volume (Anti-M-50 %) even under harsh environments of À20 8 8Ca nd 60 8 8C. Additionally,t he suppressed side reactions and dendrite-free Zn plating/stripping in Anti-M-50 %e lectrolyte significantly enhance performance of Zn/ polyaniline coin and pouchcells.Wedemonstrate this low-cost strategy can be readily generalized to other solvents,indicating its practical universality.R esults will be of immediate interest and benefit to ar ange of researchers in electrochemistry and energy storage.

Aqueous Zn-ion batteries (ZIBs) have inspired an overwhelming literature surge due to their safety, cost effectiveness, and environmental benignity. Directly employing metallic Zn foil as anode significantly simplifies battery manufacturing...

H2 evolution is the reason for poor reversibility and limited cycle stability with Zn‐metal anodes, and impedes practical application in aqueous zinc‐ion batteries (AZIBs). Here, using a combined gas chromatography experiment and computation, it is demonstrated that H2 evolution primarily originates from solvated water, rather than free water without interaction with Zn2+. Using linear sweep voltammetry (LSV) in salt electrolytes, H2 evolution is evidenced to occur at a more negative potential than zinc reduction because of the high overpotential against H2 evolution on Zn metal. The hypothesis is tested and, using a glycine additive to reduce solvated water, it is confirmed that H2 evolution and “parasitic” side reactions are suppressed on the Zn anode. This electrolyte additive is evidenced to suppress H2 evolution, reduce corrosion, and give a uniform Zn deposition in Zn|Zn and Zn|Cu cells. It is demonstrated that Zn|PANI (highly conductive polyaniline) full cells exhibit boosted electrochemical performance in 1 M ZnSO4–3 M glycine electrolyte. It is concluded that this new understanding of electrochemistry of H2 evolution can be used for design of relatively low‐cost and safe AZIBs for practical large‐scale energy storage.