Carbon-encapsulated V(2)O(3) nanorods for high-performance aqueous Zn-ion batteries

Searching for stable cathodes is of paramount importance to the commercial development of low-cost and safe aqueous Zn-ion batteries (AZIBs). V(2)O(3) is a good candidate for AZIB cathodes but has unsatisfied cycling stability. Herein, we solve the stability issue of a V(2)O(3) cathode by coating a robust carbon shell. Strong evidence was provided that V(2)O(3) was oxidized to favorable V(2)O(5)·nH(2)O during charging and the carbon shell could promote the oxidation of V(2)O(3) to V(2)O(5)·nH(2)O. The discharge capacity was increased from ∼45 mA h g(−1) to 336 mA h g(−1) after V(2)O(3) was oxidized to V(2)O(5)·nH(2)O, indicating a higher Zn(2+)-storage capability of V(2)O(5)·nH(2)O than V(2)O(3). In addition, the rate-capability and long-term cycling performance are greatly enhanced after coating carbon shells on the surface of V(2)O(3) nanorods. Therefore, the presented strategy of introducing carbon shells and fundamental insights into the favorable role of carbon shells in this study contribute to the advancement of highly stable AZIBs.