V-doped T-Nb2O5 toward high-performance Mg2+/Li+ hybrid ion batteries

Abstract

Developing high-rate capability and long-term cycling stability cathode materials is an unremitting pursuit for the development of Mg²⁺/Li⁺ hybrid ion batteries. Herein, V-doped T-Nb₂O₅ sub-microspheres (labeled as VTNO-x, x = 1, 2, 3) were produced by a facile solvothermal reaction. The optimized VTNO-3 delivers a high reversible capacity of 208.8 mA h g⁻¹ at 0.5C, outstanding rate performance of 107.8 mA h g⁻¹ at 10C and long-term cycling stability with capacity retention of 82.2% at 5C up to 5000 cycles. The characterization results show that V-doping reduces the band gap, increases ionic diffusion coefficient and maintains structural stability, resulting in enhanced electronic conductivity, ionic conductivity and structural stability, and thus bestow T-Nb₂O₅ with excellent electrochemical performances. This work paves a new path for constructing high-rate electrode materials for energy storage.