Proton-assisted mixed-valence vanadium oxides cathode with long-term stability for rechargeable aqueous zinc ion batteries

• Long-term stability zinc ions batteries were developed. • The VOHG material has V 4+ /V 5+ mixed valent vanadium and a special layer structure with interlayer water. • The VOHG RA-ZIBs exhibit an ultra-high specific capacity and superior rate performance. • The VOHG RA-ZIBs have 10,000 times long cycle life at ultra-large current density of 10 A g −1 . • The reactions of the VOHG RA-ZIBs were first explained by Zn 2+ /H + co-(de)intercalation mechanism and Grotthuss proton transport mechanism. In this work, we developed a rGO assisted vanadium oxide xerogel (abbreviate as VOHG) as cathode material for rechargeable aqueous zinc ion batteries (RA-ZIBs). The VOHG cathode exhibits an ultra-high specific capacity of 625 mA h g −1 at current density of 0.1 A g −1 , superior reversibility and a long cycle life with a coulombic efficiency of 100.0% after 10,000 cycles. The VOHG material has mixed valent vanadium ions V 4+ /V 5+ and a layer structure with interlayer water. The interlayer water acts as soft support for the VO 6 octahedron, forming a large space in the layers for H + /Zn 2+ intercalation, which improves the migration rate of Zn 2+ due to its charge shielding effect. Protons can move quickly through the interlayer water network by Grotthuss proton transport mechanism. The application of the unique structure of VOHG makes zinc ions battery will be a promising candidate of energy storage device with high-capacity and long cycle stability. Schematic illustration of the electrochemical mechanism of VOHG RA-ZIBs. Protons rapidly migrated through Grotthuss proton transport mechanism and co-(de)intercalated with zinc ions in VOHG cathode for Long-term stability rechargeable aqueous zinc ion batteries.