Tailoring Oxygen Site Defects of Vanadium-Based Materials through Bromine Anion Doping for Advanced Energy Storage

Captivated by their strong ion-storage capacities, vanadium (V)-based cathode materials have triggered plenty of active research. However, these materials still suffer from unstable lattice structures, always accompanied by inferior rate capabilities. Herein, with the introduction of bromine ions, the oriented growth was tailored to form smaller rod-like particles, while the resultant charge unbalance brought about the creation of oxygen defects, boosting the broadening of energy distribution with fast redox reactions. The as-targeted sample displayed a lithium ion storage capacity of 280 mA h g^–1, which was still maintained at about 252 mA h g^–1 after several cycles. As zinc-ion battery cathodes, a capacity of 247 mA h g^–1 could be retained at 0.5 A g^–1 after 100 cycles. Even at a high current density of 3.0 A g^–1, the capacity was retained at about 207 mA h g^–1 after 500 cycles. Supported by a series of advanced technologies, the enhanced redox activity of V ions was detected owing to the unbalance of charge from bromine doping. Moreover, a detailed kinetic analysis and in situ resistance measurements further demonstrated the enhancement of surface-controlling contributions and in-depth redox reactions. Given that, this work was anticipated to offer a significant perspective about rational surface-/interface-enhanced properties of advanced energy-storage materials.