Boosting the Electrochemical Performance of V₂O₃ by Anchoring on Carbon Nanotube Microspheres with Macrovoids for Ultrafast and Long-Life Aqueous Zinc-Ion Batteries

Zinc-ion batteries (ZIBs) are next-generation energy storage systems with high safety and environmental friendliness because they can be operated in aqueous systems. However, the search for electrode materials with ideal nanostructures and compositions for aqueous ZIBs is in progress. Herein, the synthesis of porous microspheres, consisting of V₂O₃ anchored on entangled carbon nanotubes (p-V₂O₃-CNT) and their application as cathode for ZIBs is reported. From various analyses, it is revealed that V₂O₃ phase disappears after the initial charge process, and Zn_3+x(OH)_2+3xV_2−xO_7−3x∙2H₂O and zinc vanadate (Zn_yVO_z) phases undergo zinc-ion intercalation/deintercalation processes from the second cycle. Additionally, the electrochemical performances of p-V₂O₃-CNT, V₂O₃-CNT (without macrovoids), and porous V₂O₃ (without CNTs) microspheres are compared to determine the effects of nanostructures and conductive carbonaceous matrix on the zinc-ion storage performance. p-V₂O₃-CNT exhibits a high reversible capacity of 237 mA h g⁻¹ after 5000 cycles at 10 A g⁻¹. Furthermore, a reversible capacity of 211 mA h g⁻¹ is obtained at an extremely high current density of 50 A g⁻¹. The macrovoids in V₂O₃ nanostructure effectively alleviate the volume changes during cycling, and the entangled CNTs with high electrical conductivity assist in achieving fast electrochemical kinetics.