Rapid Electrochemical Activation of V O @C Cathode for High-Performance Zinc-Ion Batteries in Water-in-Salt Electrolyte.

Aqueous Zn-ion batteries (ZIBs), with the advantages of low cost, high safety, and high capacity, have great potential for application in grid energy storage and wearable flexible devices. However, their commercial application is still restricted by their inferior long-term cycling stability, Zn dendrite formation, and the decomposition of aqueous electrolyte. In this study, a Zn|Zn(CF SO ) +LiTFSI|V O @C cell is constructed to address the above issues. The V O @C electrode can be fully oxidized into amorphous V O @C simultaneously with Zn and H O co-insertion. The cell delivers a high specific capacity of more than 240 mAh g at 3 A g , with extraordinary coulombic efficiency and capacity retention. The excellent electrochemical performances are attributed to synergistic effects between the V O @C electrode and the water-in-salt electrolyte with enhanced stability and improved interface reaction kinetics. Systematic improvements of this architecture indicate much promise for application.