CVD-Grown Carbon Nanofibers on Knitted Carbon Fabric for Enhanced Supercapacitor Performance

Integrating nanostructured carbon materials with flexible substrates to form binder-free electrode architectures is a promising strategy for enhancing the capacitive performance and rate capability of supercapacitors, yet it remains a significant challenge. In this study, we report a facile method for the direct synthesis of carbon nanofibers (CNFs) on knitted carbon fabric (CF) via chemical vapor deposition (CVD), enabling their use as electrodes in all-solid-state flexible supercapacitors. The resulting CNFs exhibit two typical average diameters—approximately 25 nm and 50 nm—depending on the growth temperature, with both displaying highly graphitized structures. The electrochemical performance of CNFs/CF electrodes was evaluated in 1 M H2SO4 aqueous electrolyte using cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS), confirming electric double-layer capacitor (EDLC) behavior. Notably, the 25 nm-CNFs/CF electrode achieves a high specific capacitance of 87.5 F/g, significantly outperforming the 50 nm-CNFs/CF electrode, which reaches 50.2 F/g. Compared to previously reported carbon nanotube (CNT)/CF electrodes, the 25 nm-CNFs/CF electrode exhibits superior capacitance and lower resistance. These results underscore its strong potential for application in flexible and wearable electronic devices. Furthermore, the structure-performance relationship revealed in this study provides valuable insights for the rational design of next-generation carbon-based energy storage systems.