V2O5-Conductive polymer nanocables with built-in local electric field derived from interfacial oxygen vacancies for high energy density supercapacitors

Generating oxygen vacancies (Vo) in vanadium pentoxide (V2O5) has been demonstrated as an effective approach to tailor its electrochemical properties. The present study investigates three different kinds of conductive polymer (CP = PPy, PEDOT, and PANI) coated V2O5 nanofibers with Vo generated at the interface during the polymerization process. Surface Vo form a local electric field and promote the charge transfer kinetics of the resulting Vo-V2O5/CP nanocables, and the accompanying V4+ and V3+ ions may also catalyze the redox reactions and improve the supercapacitor performance. The differences and similarities of three different CP coatings have been compared and discussed, and are dependent on their polymerization conditions and coating thickness. The distribution of Vo in the surface layer and in the bulk has been elaborated and the corresponding effects on the electrochemical properties and supercapacitor performance have also been investigated. Vo-V2O5/CP can deliver a high capacity of up to 614 F g(-1) at a current rate of 0.5 A g(-1) and supercapacitors with Vo-V2O5/CP demonstrated excellent cycling stability over 15 000 cycles at a rate of 10 A g(-1).