Quinone-rich N-carbon spheres loaded carbon cloth as high-performance electrode for double-layer capacitor

The binder-free carbon cloth-based composites have shown their promises as capacitor electrodes with larger capacities and low resistances. Their porous structures and surface properties accounted for the enhanced electrochemical performance. In this work, the quinone-rich N-doped carbon spherical composites were loaded on the carbon cloth (Q-NCS-CC) and then applied as an electrode for electric double-layer capacitors (EDLCs). Contributed by the EDLC and surface capacitances, the Q-NCS-CC electrode composite achieved a high area-specific capacitance of 1863 mF cm⁻² at 1 mA cm⁻², and the contribution of surface capacitance reached 53% at a scan rate of 50 mV s⁻¹. The further performance evaluation showed that the Q-NCS-CC composite-incorporated EDLC delivered a capacitor of 707.76 mF cm⁻² at 8 mA cm⁻². The long-term stability tests displayed a cycling capacitance retention of 97% at 15 mA cm⁻² after 20,000 cycles.