Gradient Oxygen Vacancies in V2O5/PEDOT Nanocables for High-Performance Supercapacitors

V2O5/poly(3,4-ethylenedioxythiophene) nanocables with oxygen vacancies gradually decreasing from the surface to the core (G-V2O5/PEDOT nanocables) were prepared as electrodes for supercapacitors. Gradient oxygen vacancies formed when 3,4-ethylenedioxythiophene monomers polymerized conformally on the surface of V2O5 nanofibers, providing G-V2O5/PEDOT nanocables with much improved charge storage kinetics and structural durability. The role of gradient oxygen vacancies in enhancing charge transfer/transport was also evidenced by means of density functional theory calculations. G-V2O5/PEDOT nanocable-based supercapacitors showed excellent electrochemical performance with a high specific capacitance of 614 F g(-1) and energy density of 85 W h kg(-1) in neutral aqueous electrolyte. The synergistic combination of gradient oxygen vacancies and polymer shell provided the G-V2O5/PEDOT nanocable-based supercapacitors with an excellent long cycling life with 122% capacitance retention after 50 000 cycles. Without any additional oxidizing agent, this simple synthesis method is cost competitive and ready for scale up manufacturing for such energy storage electrode materials.