Designing Electrolyte Structure to Suppress Hydrogen Evolution Reaction in Aqueous Batteries

Aqueous batteries (ABs) have attracted increasing attention because of their inherent safety and low cost. Nevertheless, hydrogen evolution reaction (HER) at the anode presents severe challenges for stable safe operation ABs. Instead passivating surface to hinder HER kinetics, a design strategy is proposed here suppress via alternating its thermodynamics pathway. Addition bond acceptor, dimethyl sulfoxide (DMSO) can delay onset potential by as much 1.0 V (on titanium mesh). Spectral characterization molecular dynamics simulation confirm that formation bonds between DMSO water molecules reduce activity, thereby suppressing HER. This has proven be universal in expanding electrochemical window aqueous electrolytes. For instance, unconventional V2+ ↔ V3+ redox processes Na3V2(PO4)3 (−1.2 versus Ag/AgCl) realized