Self-standing V2O5/Polydopamine/CNT film as high-performance cathode material for advanced zinc-ion batteries

Rechargeable aqueous zinc-ion battery (ZIB) is regarded as a strategic technology for energy storage and conversion in high-power, high-safety applications. Nonetheless, the primary challenge lies in the development of high-performance cathode materials. In this work, we report for the first time a self-standing V2O5/polydop- 2 O 5 /polydop- amine/CNT (V2O5/PDA/CNT) 2 O 5 /PDA/CNT) electrode that shows outstanding electrochemical performance as cathode material for zinc-ion batteries. A polydopamine coating was applied to the surface of V2O5 2 O 5 particles through a facile self-polymerization process of dopamine. The PDA coating was confirmed and studied by TEM, TGA, FTIR-ATR, and XPS (O 1s & V 2p, C 1s and N 1s). Polydopamine thin layer leads to the partial reduction of V 5+ to V4+. 4+ . Combining V2O5/PDA 2 O 5 /PDA with CNT allowed us to obtain a self-standing, binder-free cathode material with a high capacity of similar to 530 mAh g- 1 at 0.1 A g- 1 . The developed electrode demonstrates excellent rate capability. Indeed, even with a 25-fold increase in current density (from 0.2 A g- 1 to 5 A g-- 1 ), V2O5/PDA/CNT-b 2 O 5 /PDA/CNT-b retains 94 % of its capacity. In addition, the new electrode exhibits long-term cycle stability enduring up to 1000 cycles at high current density with excellentcapacity retention. The combination of PDA coating with the incorporation of carbon nanotube appears to be an excellent strategy for enhancing the electrochemical performance and stability of V2O5 2 O 5 for ZIBs.