Latent Solvent Induced Reliable Interfacial Chemistry Toward Highly Reversible Zn Anodes

AbstractAqueous zinc‐ion batteries have garnered renewed interest owing to their inherent safety and cost‐effectiveness. However, Zn anode suffers from notorious side reactions and dendrite growth, compromising the battery performance. Designing anion‐containing solvation structures to facilitate the in situ formation of a solid electrolyte interphase (SEI) layer proves effective in protecting Zn anode, yet balancing the inherent interactions between the cations‐solvents and cations–anions remains a significant challenge. Herein, latent solvent (hexafluoroisopropanol) with specific anion‐philic and cation‐phobic properties is introduced, which can remarkably increase Zn(TFSI)2 solubility in water and induce anion‐containing solvation structures. The introduction of latent solvent enables anions to preferentially decompose, giving rise to an anion‐derived SEI layer. More interestingly, the direct anion‐cation interaction endows Zn2+ species with stepwise dehydration, minimizing the adsorption of water on Zn anode. The anion‐derived SEI layer and optimized de‐solvation process work in synergy to enable homogeneous Zn deposition and ensure high reversibility. When coupled with a NaV3O8·1.5H2O (NVO) cathode, the resultant full cell delivers a high‐capacity retention of 87.8% after 2000 cycles at 1 A g−1. This work provides valuable insights into the advanced latent solvent electrolyte design and beyond.