Oxygen Vacancy Engineering of TiO₂/WO₃ Composites on a Carbon Fiber as Advanced Electrodes for High-Performance Flexible Supercapacitors

Flexible fiber-based supercapacitors (SCs) are promising energy supply systems for portable and wearable electronics. In this work, we reported the in situ growth of reduced hybrid metal oxides (R-TiO 2 /WO 3 ) with oxygen vacancies on a carbon fiber (CF) for flexible symmetric SCs. It was found that the synergistic effect of the TiO 2 /WO 3 heterojunction and oxygen vacancy engineering could significantly reduce the work function, which accelerated charge transmission at the electrode/electrolyte interface, thereby dramatically enhancing the electrochemical performance. The R-TiO 2 /WO 3 /CF electrode exhibited a higher capacitance of 102 F g –1 and a prominent long-term stability of about 97.64%. The R-TiO 2 /WO 3 /CF-SC exhibited an attractive energy density of 61.2 Wh kg –1 at a power density of 2160 W kg –1 . Moreover, we assembled an all-solid-state flexible SC (R-TiO 2 /WO 3 /CF-AFSC) by employing a gel electrolyte, and it could exhibit satisfying long-term stability and maintained favorable flexibility. The facile assembly, favorable flexibility, and remarkable electrochemical performance enabled the R-TiO 2 /WO 3 /CF composite systems with rich oxygen vacancies to demonstrate enormous potential for the next-generation intelligent energy supply systems.