Supercapacitor based on the redox of quinone-carbon negative electrode with high cycle performance

A high specific surface area sucrose-derived porous carbon (SPC) using ZnCl2 as a salt template was successfully synthesized. Anthraquinone (AQ) molecules were then immobilized onto the SPC surface via the non-covalent functionalization approach to prepare the quinone-carbon (AQ/SPC) composites. The synthesized composites exhibited excellent self-synergy properties because of SPC's effective three-dimensional (3D) electron transmission network and the rapid-reversible interfacial proton-coupled electron transfer reaction of AQ molecules. Our experimental results indicated that the AQ/SPC-3 electrode in the three-electrode system with a 1 M H2SO4 electrolyte gave the highest specific capacitance (400.7 F g−1), more than twice that of SPC (155.1 F g−1) at a 1 A g−1 current density, exhibiting excellent rate capability and electrochemical reversibility. The cyclic voltammetry of AQ/SPC-3 also exhibited a symmetric and reversible redox peak at negative potential. Hence, we assembled an asymmetric supercapacitor (SPC@AQ/SPC-3) with a two-electrode system and tested it under the same conditions as the three-electrode system. The SPC@AQ/SPC system yielded 71.3 F g−1 and 11.8 Wh kg−1 at 50 W kg−1. At a 5 A g−1 current density, all the SPC@AQ/SPC-3, SPC@DCAQ/SPC-1, and SPC@DMAQ/SPC-1 systems could establish at least 96.94 % of high cycle stability after 10,000 cycles. Notably, by comparing the electron-withdrawing group (Cl) with the electron-donating group (NH2) at the same substitution position of AQ, we found that the electron-withdrawing group has a noticeable promotion effect on redox reversibility and long-term cycle stability.