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.