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

Abstract

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.