Boosting Capacitive Performance of S-Doped Carbon Fibers via Substrate-Oriented Activation Methodology

S-doped capacitive carbon fiber (S-CCF) with an independent microarchitecture decorated with micromesoporous channels is obtained via the coupling technique between substrate orientation and activation using coal pitch as a carbon source. Micropores and mesopores in S-CCF are derived from activation and substrate-oriented principles, respectively. The incorporation of S-containing functional groups into carbon skeletons realized via the redox reaction between sulfate and coal pitch contributes to further increasing the defect or disorder degree and enhancing the hydrophilicity. Higher capacitance and better rate capability over those of doped-free CCF and activation-derived carbon are afforded by the S-CCF. S-CCF also presents extraordinary high-loading behavior, in which satisfied gravimetric and areal capacitances (233 F·g–1 and 2332 mF·cm–2, respectively) are able to be guaranteed simultaneously, demonstrating its strong antipolarization and robustness. In Li-based organic electrolytes, an S-CCF-based Li-ion capacitor delivers excellent electrode performance in terms of capacitance, rate capability, Ragone performance, and cyclability.