Anion Additive Integrated Electric Double Layer and Solvation Shell for Aqueous Zinc Ion Battery

Aqueous zinc ion batteries (AZIBs) show great potential in large-scale energy storage systems. However, the inferior cycling life due to water-induced parasitic reactions and uncontrollable dendrites growth impede their application. Electrolyte optimization via the use of additives is a promising strategy to enhance the stability of AZIBs. Nevertheless, the mechanism of optimal multifunctional additive strategy requires further exploration. Herein, sodium dodecyl benzene sulfonate (SDBS) is proposed as a dual-functional additive in ZnSO₄ electrolyte. Benefiting from the additive, both side reactions and zinc dendrites growth are significantly inhibited. Further, a synchrotron radiational spectroscopic study is employed to investigate SDB^- adjusted electric double layer (EDL) near the Zn surface and the optimized solvation sheath of Zn²⁺. First-principles calculations verify the firm adsorption of SDB^-, and restriction of random diffusion of Zn²⁺ on the Zn surface. In particular, the SDBS additive endows Zn||Zn symmetric cells with a 1035 h ultra-stable plating/stripping at 0.2 mA cm^-2. This work not only provides a promising design strategy by dual-functional electrolyte additives for high stable AZIBs, but also exhibits the prospect of synchrotron radiation spectroscopy analysis on surface EDL and Zn²⁺ solvation shell optimization.