Manifesting the Carrier Behavior of a Vanadium Oxide/Carbon Composite Cathode in Aqueous Zinc-Ion Batteries

In the development of aqueous zinc-ion batteries (AZIBs), carbon materials have received significant interest as supporting materials for vanadium-based oxides. To improve the performance of AZIBs, in this study, amorphous V2O5 embedded carbon nanofiber composites (a-V2O5@NCNFs) are constructed by an electrostatic spinning technique. The uniformly embedded structure of a-V2O5 in carbon nanofibers not only endows an excellent electrical conductivity and structural stability but also effectively inhibits vanadium dissolution in the aqueous electrolyte. Furthermore, the presence of carbon on the a-V2O5 surface creates important effects on the intercalation of Zn2+ and H+. Specifically, the nitrogen-doped carbon on the a-V2O5 surface increases the intercalation of H+, which is beneficial to maintain the structural stability of a-V2O5@NCNFs. Consequently, an optimized a-V2O5@NCNFs-4 cathode exhibits excellent rate performance with the discharge specific capacity of 196 mAh g–1 at 21 A g–1 and a long cycling life with the capacity retention of 87.3% at 5 A g–1 after 5000 cycles. This study gained further insights into the energy storage mechanism of vanadium oxide/carbon composite cathodes.