Tubular carbon nanofibers decorated with RuO₂ nanorods toward flexible electrochemical capacitors

RuO₂ nanorod-decorated tubular carbon nanofibers(CNFs) are carefully fabricated by adjusting the recrystallization temperature for use in high-performance electrochemical capacitors. The tubular structured CNFs/RuO₂ electrodes provide a short diffusion path for the ion transport through the inner hollow channel that allowed the maximum utilization of the active sites of the amorphous RuO₂ nanomaterials at the electrode/electrolyte interface. The optimized the tubular structured CNFs/RuO₂ electrodes exhibit good rate capability with a high surface capacitance, energy density, and good long-term cycling stability of 190 Fg⁻¹, 22 Whkg⁻¹, and 94% after 10,000 cycles, respectively, in an aqueous solution. The asymmetric cell presents a wide and stable operating voltage window, which greatly improves the energy density stored in the asymmetric device. In addition, there is no noticeable difference in the electrochemical properties under bent states, making it a flexible energy storage device for wearable applications. Hence, flexible supercapacitors using CNFs/RuO₂ electrodes with the tubular structure show low resistance, high capacitance, good rate retention, and excellent cycle stability, making it a promising material for energy storage applications.