Facile fabrication of rGO/CNT hybrid fibers for high-performance flexible supercapacitors

Novel reduced graphene oxide and carbon nanotube (rGO/CNT) hybrid fibers were prepared using a facial low-temperature chemical reduction self-assembly with vitamin C as the reducing agent. Mechanical measurements showed that hybrid fibers with an ultimate elongation of 150% had better mechanical properties than the single rGO fiber with an ultimate elongation of 105%. Cyclic voltammetry (CV) results showed that rGO/CNTs hybrid fibers exhibited better electrochemical performance than the rGO fiber because of the larger CV curve area of the former. The volumetric specific capacitance of the rGO/CNTs electrode was 559.9 F cm⁻³, and its qualitative specific capacitance was 59.76 F g⁻¹ at a high current density of 1 A g⁻¹. Both the volumetric specific capacitance and qualitative specific capacitance of the rGO/CNTs hybrid fibers were higher than those of single rGO fibers, particularly at low sweep speed. The scanning electron microscopy and transmission electron microscopy images of the rGO/CNTs composite fiber clearly showed the rGO and CNTs co-assembly and the interconnected porous structure formation. In the hybrid nanostructure, CNTs served as a reinforced bar, and the synergic effect between rGO and CNTs led to hybrid fibers with enhanced mechanical and electrochemical performances. The flexible rGO/CNT hybrid fibers showed large volumetric capacity, good rate capability, high stability and excellent flexibility. The micro-SCs made of the rGO/CNT hybrid fibers electrode are ideal energy-storage devices for next-generation flexible wearable electronics.