Coupling Solvation Structure Regulation and Interface Engineering via Reverse Micelle Strategy Toward Highly Stable Zn Metal Anode

Abstract

The stability of aqueous Z inc (Zn) ion energy storage devices is significantly compromised by the instability at the electrode/electrolyte interface, which can result in the growth of Zn dendrites, self‐corrosion, and various other side reactions. Regulating the Zn‐ion （Zn2+) solvation structure through electrolyte additives has been proved to be effective strategy in stabilizing the Zn anode, but the influence of free water on the solvation structure is often lacking in‐depth exploration. Herein, the piperazine‐N,N‐bis(2‐hydroxypropanesulfonic acid) sodium salt (POPSO‐Na) is presented as a multifunctional electrolyte additive, which enhances the stability of the Zn anode by modulating the deposition and stripping environment of Zn2⁺ and limiting the presence of free water in the electrolyte during cycling. Theoretical calculation and experimental results demonstrate that the POPSO‐Na additive can not only replace the structural water around Zn2+ to destroy the original solvation sheath, but also form reverse micelle interface structure to hinder the proton transition and constrain the free water in the electrolyte. Thus, the Zn||Zn battery utilizing the ZnSO4+POPSO‐Na electrolyte exhibits an impressive cycle life of 1600 h at a current density of 1 mA cm−2, achieving an average Coulomb efficiency (CE) of ≈100%, which is significantly better than that observed with the ZnSO4 electrolyte. Moreover, the Zn||Cu battery with ZnSO4+POPSO‐Na electrolyte achieves high stability even after cycling for over 2000 h.