Synergistic effect of the co-solvent induced interfacial chemistries in aqueous Zn batteries

Aqueous zinc-ion batteries (ZIBs) have garnered significant attention due to their high energy, intrinsic safety, and environmental friendliness. NASICON-type compounds are promising cathode candidates in aqueous batteries due to their high ionic conductivity , and high operating voltage. However, these materials, e.g., Na 3 V 2 (PO 4 ) 3 , suffer from inevitable structural degradation and dissolution in aqueous electrolytes, thus hampering their practical performance in aqueous batteries. Interfacial chemistry modulation by electrolyte engineering is beneficial for stabilizing Zn metal anode and high-voltage cathodes in ZIBs . Herein, the interfacial chemistries in an engineered non-concentrated aqueous electrolyte by co-solvent strategy are reported, which synergistically enables high reversibility of Zn anode and long cycling stability of Na 3 V 2 (PO 4 ) 3 cathode. Consequently, the Zn||Na 3 V 2 (PO 4 ) 3 full-cell exhibits high Coulombic efficiency (∼99.3% in average) with a prolonged cycling life, which can be ascribed to the synergistic-effect of the solid-electrolyte interphases with unique organic/inorganic hybrid structures on the electrodes. This work discloses the structures of the interphases formed on the electrodes induced by co-solvent strategy in aqueous electrolytes and their working mechanisms in stabilizing the aqueous Zn batteries, which will guide the future design of advanced aqueous electrolytes with unique interfacial chemistries for batteries.