Flexible all-solid-state asymmetric supercapacitor based on transition metal oxide nanorods/reduced graphene oxide hybrid fibers with high energy density

Fiber-shaped flexible supercapacitors have attracted considerable attention in recent years due to their potential application in wearable electronics. However, the limited energy density is still a serious bottleneck which restricts their practical application. In this work, transition metal oxide nanorods/reduced graphene oxide (rGO) hybrid fibers were prepared by a facile, scalable wet-spinning method. Due to the synergetic effects between transition metal oxide nanorods and rGO, the electrochemical performance of the hybrid fibers were greatly improved. An all-solid-state asymmetric supercapacitor was constructed by using MnO2 nanorods/rGO hybrid fiber as positive electrode, MoO3 nanorods/rGO hybrid fiber as negative electrode and H3PO4/poly(vinyl alcohol) (PVA) as electrolyte. Based on the different working potential window between MnO2 and MoO3, the optimized asymmetric supercapacitor can be cycled reversibly at a high voltage of 1.6 V and deliver a superior volumetric energy density of 18.2 mWh cm−3 at a power density of 76.4 mW cm−3. Besides, the asymmetric supercapacitor exhibits remarkable cycling stability and excellent flexibility and mechanical stability.