Architecting a High-Energy-Density Rocking-Chair Zinc-Ion Batteries via Carbon-Wrapped Vanadium Dioxide

Aqueous zinc-ion batteries (ZIBs) show great potential in large-scale energy storage applications because of their low cost and high safety features, whereas the inefficient zinc utilization and uncontrollable dendrite issue of the zinc metal anode greatly limit their energy density and cycling stability. Herein, a carbon-wrapped vanadium dioxide (VO2@C) core-shell composite has been prepared and utilized as an intercalated anode of "rocking-chair" ZIBs. Benefiting from the carbon shell, the charge transfer and structural stability of VO2@C have been significantly improved, thus delivering a specific capacity of 425 mA h g-1 at 0.1 A g-1 and a capacity retention of 94.9% after 3000 cycles at 5 A g-1, better than that of VO2 (338 mA h g-1 and 59.2%). Further, the low Zn2+ intercalated potential (0.54 V vs Zn2+/Zn) and reversible Zn2+ intercalation/deintercalation behavior of VO2@C enable the successful construction of VO2@C||ZnMn2O4 "rocking-chair" ZIBs, which achieve a capacity of 104 mA h g-1 at 0.1 A g-1 and an exceptional energy density of 96.3 W h kg-1 at 74.1 W kg-1 (based on the total weight). This research enriches the currently available options for constructing high-energy-density energy storage systems.