Electrospun carbon nanofiber‐supported V2O3 with enriched oxygen vacancies as a free‐standing high‐rate anode for an all‐vanadium‐based full battery

Synergistic regulation of hierarchical nanostructures and defect engineering is effective in accelerating electron and ion transport for metal oxide electrodes. Herein, carbon nanofiber‐supported V2O3 with enriched oxygen vacancies (OV‐V2O3@CNF) was fabricated using the facile electrospinning method, followed by thermal reduction. Differing from the traditional particles embedded within carbon nanofibers or irregularly distributed between carbon nanofibers, the free‐standing OV‐V2O3@CNF allows for V2O3 nanosheets to grow vertically on one‐dimensional (1D) carbon nanofibers, enabling abundant active sites, shortened ion diffusion pathway, continuous electron transport, and robust structural stability. Meanwhile, density functional theory calculations confirmed that the oxygen vacancies can promote intrinsic electron conductivity and reduce ion diffusion energy barrier. Consequently, the OV‐V2O3@CNF anode delivers a large reversible capacity of 812 mAh g−1 at 0.1 A g−1, superior rate capability (405 mAh g−1 at 5 A g−1), and long cycle life (378 mAh g−1 at 5 A g−1 after 1000 cycles). Moreover, an all‐vanadium full battery (V2O5//OV‐V2O3@CNF) was assembled using an OV‐V2O3@CNF anode and a V2O5 cathode, which outputs a working voltage of 2.5 V with high energy density and power density, suggesting promising practical application. This work offers fresh perspectives on constructing hierarchical 1D nanofiber electrodes by combining defect engineering and electrospinning technology. A free‐standing hierarchically electrospun anode of oxygen vacancy‐enriched V2O3 nanosheets around carbon nanofibers was readily fabricated that showed high electron transport capability, low ion diffusion barrier, fully exposed active sites, and strong structural stability. Accordingly, an all‐vanadium full battery using the V2O5 cathode delivers an energy density of 82 Wh kg−1 at a power density of 6560 W kg−1 at a working voltage of 2.5 V, boosting practical applications.