Hydrothermally synthesized RuO2/Carbon nanofibers composites for use in high-rate supercapacitor electrodes

A conventional hydrothermal deposition process is used to graft ruthenium oxide (RuO₂) nanoparticles onto carbon nanofibers (CNFs). The obtained RuO₂ nanoparticles have an average diameter of 2 nm and are homogenously distributed on the CNF surfaces. Supercapacitors are fabricated using the resulting RuO₂ grafted CNFs nanocomposite as the electrodes. The existence of CNFs leads to reduced contact resistance among the RuO₂ nanoparticles and provides a network for fast electron transport, which then contributes to enhanced electrochemical performance. The enhancement is proportional to the RuO₂ content and can be as high as 638% at a high sweep rate of 200 mV s⁻¹, at which a capacitance is 155 F g⁻¹. Stability of the RuO₂-grafted CNF capacitor is also demonstrated by subjecting the capacitor to a potential sweep at 500 mV s⁻¹ for 1000 cycles. Furthermore, the RuO₂ grafted CNF capacitor exhibits a very short relaxation time of 0.17 s, which is desirable for high rate charge and discharge.