Self-sulfur doped mesoporous novel carbon electrodes derived from poly-anthraquinone sulfide for high-performance supercapacitors! A comparative study

Carbon materials are suitable electrode candidates in supercapacitors (SCs) because of their availability, well-defined microstructures, and ultrahigh surface areas. Herein, a universal chemical activation method was utilized to obtain activated carbon (C-KOH) from poly-anthraquinone sulfide (PAQS) at 850 °C and reduced activated carbon (C-KOH-H) from C-KOH via a mild hydrogen reduction process at low temperature. The electrochemical performances of the PAQS derived activated carbon electrodes were investigated by assembling electric double-layer capacitors (EDLCs). Electrodes fabricated from C-KOH and C-KOH-H showed 174 and 182.3 F g⁻¹ specific capacitances at 0.5 A g⁻¹ current density, respectively. Whereas their energy densities were 44 and 46 Wh kg⁻¹ at 350 and 423 W kg⁻¹ power densities, respectively. SCs assembled from C-KOH-H showed excellent rate performance, that retained 140 F g⁻¹ even at high current density (20 A g⁻¹), while the one assembled with C-KOH stored 54 F g⁻¹. Furthermore, the C-KOH-H electrode retained 98 % of the initial capacitance at 1 A g⁻¹ over 20,000 continuous cycles. The experimental results revealed that C-KOH-H showed the best electrochemical performance in SCs, which is attributed to the presence of less sulfur and oxygen than C-KOH after the mild reduction. These results prove that PAQS show excellent activation with KOH to produce well-organized porous activated carbons having high specific surface areas, which can be utilized as high-performance electrode materials in SCs.