Simultaneous regulation of interface chemistry and solvation structure by multifunctional organic salt anions for durable zinc anodes

Abstract

Zn²⁺ deposition behavior and complex side-reactions at the zinc metal electrode/electrolyte interface significantly impact battery stability. Despite progress in electrolyte design, the regulatory mechanism of multifunctional organic salt anions at the electrode/electrolyte interface requires further investigation. In this study, dodecylbenzene sulfonate was selected as a representative multifunctional organic salt anion (DBS⁻) donor, successfully inducing the restructuring of both the solvation structure and the Helmholtz plane. The introduction of DBS⁻ not only replaced some coordinated water molecules in the solvation shell through its strong interaction with Zn²⁺ but also preferentially adsorbed onto the Zn anode interface due to its sulfonate groups, thereby repelling active free water molecules and effectively suppressing side reactions initiated by water decomposition. Additionally, DBS⁻ undergoes preferential in-situ decomposition, forming a complete and dense organic–inorganic hybrid SEI layer that significantly enhances the long-term reversibility of Zn plating/stripping. Thus, the symmetrical battery achieves a cycle life of 4500 h at 1 mA cm⁻²/1 mAh cm⁻², extending battery life nearly 60-fold compared to cells with ZS electrolyte. Even under higher test conditions, the introduction of DBS⁻ substantially improves cycling stability. Besides, the Zn‖MnO₂@CNT battery maintains a capacity of 146.0mAh g⁻¹ after 8000 cycles at 5 A g⁻¹.