Carbon Quantum Dots Promote Coupled Valence Engineering of V O Nanobelts for High-Performance Aqueous Zinc-Ion Batteries.

Aqueous Zn-ion batteries (ZIBs) have acquired the researchers' curiosity owing to their harmlessness, cost effectiveness and high theoretical capacity of Zn anode. However, desirable cathode materials with high-capacity and high-rate are still scarce. In this work, the formation of carbon quantum dots induced vanadium pentoxide nanobelts was demonstrated via a facile one-step hydrothermal method for ZIBs. It exhibited an excellent Zn ion storage capacity of 460 mA h g at 0.1 A g , superior rate capability and stable cycling performance (above 85 % capacity retention over 1500 cycles at 4 A g ). The electrochemical kinetics and zinc ion storage mechanism were also considered. An efficient architecture-coupled valence engineering in the hybrid cathode was proposed to improve the electric conductivity, Zn ion diffusion rate, and cycling stability for ZIBs. This work may be a great motivation for further research on V O or other vanadium-based materials for high-performance ZIBs.