Electrochemical performance of activated carbon fiber with hydrogen bond-induced high sulfur/nitrogen doping

The sulfur/nitrogen co-doped activated carbon fiber (S/N-ACF) is prepared by the thermal treatment of thiourea-bonded hydroxyl-rich carbon fiber, which can bond the decomposition products of thiourea through hydrogen bond interaction to avoid the significant loss of sulfur and nitrogen sources during the thermal treatment process. The sulfur/nitrogen co-doped carbon fiber (S/N-CF) is prepared by the thermal treatment of thiourea-adsorbed carbon fiber. The doping degree of the carbon fiber is improved by reasonable strategy. S/N-ACF shows a higher amount of S/N doping (4.56 at% N and 3.16 at% S) than S/N-CF (1.25 at% N and 0.61 at% S). S/N-ACF with high S/N doping level involves highly active sites to improve the capacitive performance, and high delocalization electron to improve the conductivity and rate capability when compared with the normal S/N co-doped carbon fiber (S/N-CF). Accordingly, the specific capacitance increases from 1196 mF cm^-2 for S/N-CF to 2704 mF cm^-2 for S/N-ACF at 1 mA cm^-2. The all-solid-state flexible S/N-ACF supercapacitor achieves 184.7 μW h cm^-2 at 350 μW cm^-2. The results suggest that S/N-ACF has potential application as a CF-based supercapacitor electrode material.