Unraveling a cathode/anode compatible electrolyte for high-performance aqueous rechargeable zinc batteries

A cathode/anode compatible aqueous zinc triflate electrolyte is proposed by reorganizing the solvation structure of the electrolyte using an acetonitrile co-solvent. Acetonitrile notably alters the hydrogen bonds of the electrolyte, reducing the activity of water. Using this electrolyte, a ZnǁV₂O₅ full-cell exhibits high Coulombic efficiency, long cycle life and high rate capability. The interactions between electrolyte, cathode and Zn anode are clarified based on comprehensive in operando and ex situ experiments and molecular dynamics simulations. The addition of acetonitrile does not change the bulk ion storage of V₂O₅, but the unique electrode-electrolyte interfacial films with specific compositions and spatial distribution protect the Zn and V₂O₅ electrodes and improve the interfacial kinetics of the electrodes, thus significantly promoting the cycling performance of the full cell. This cathode/anode compatible electrolyte can overcome the challenges of both the cathode and anode which would promote aqueous rechargeable zinc batteries into practical application.