Electrospinning and electrospraying of silicon oxycarbide-derived nanoporous carbon for supercapacitor electrodes

• First report on carrier polymer free electrospun carbide derived carbon fibers.
• Use of low-cost silicon oxycarbide precursor materials.
• Synthesis of ultrafine fibers or beads by adjusting synthesis parameters.
• Comparative study of freestanding fiber mats vs. PTFE-film electrodes.
• High rate handling ability of freestanding, binder-free fiber mats.

In this study, carbide-derived carbon fibers from silicon oxycarbide precursor were synthesized by electrospinning of a commercially available silicone resin without adding a carrier polymer for the electrospinning process. The electrospun fibers were pyrolyzed yielding SiOC. Modifying the synthesis procedure, we were also able to obtain electrosprayed SiOC beads instead of fibers. After chlorine treatment, nanoporous carbon with a specific surface area of up to 2394 m2 g−1 was obtained (3089 m2 g−1 BET). Electrochemical characterization of the SiOC-CDC either as free-standing fiber mat electrodes or polymer-bound bead films was performed in 1 M tetraethylammonium tetrafluoroborate in acetonitrile (TEA-BF4 in ACN). The electrospun fibers presented a high gravimetric capacitance of 135 F g−1 at 10 mV s−1 and a very high power handling, maintaining 63% of the capacitance at 100 A g−1. Comparative data of SiOC-CDC beads and fibers show enhanced power handling for fiber mats only when the fiber network is intact, that is, a lowered performance was observed when using crushed mats that employ polymer binder.