Dual-functional triethyl phosphate additive enables stable Sn anodes in aqueous acidic batteries via interfacial...

The inactive "dead Sn" formation and the unfavorable hydrogen evolution reaction (HER) are the two issues limiting the lifespan and coulombic efficiency of Sn anodes in aqueous acidic batteries, particularly in high-areal-capacity cases. Herein, we propose the utilization of triethyl phosphate (TEP) as a bifunctional electrolyte additive to simultaneously modulate the interfacial properties and reshape the Sn²⁺ solvation structure. Systematic characterizations evidence that the presence of such dual-functional TEP additive can substantially prohibit hydrogen evolution and promote the "dead-Sn-free" Sn deposition. Accordingly, both Sn||Sn and Sn||Cu cells assembled in TEP-modified electrolyte present exceptional cycling performance, maintaining continuous operation for over 760 h at 5mAh cm^-2 and 5 mA cm^-2. When coupled with a MnO₂ cathode, the existence of TEP additive endows Sn||MnO₂ full batteries with a remarkable upgrade of rate capability and cycling stability. This study demonstrates that regulating interfacial adsorption and electrolyte solvation structure is a highly effective strategy to enhance the overall performance of Sn anodes.