Pre‐Oxidating and Pre‐Carbonizing to Regulate the Composition and Structure of Coal Tar Pitch: The Fabrication of Porous Carbon for Supercapacitor Applications

Abstract The capacitive properties of supercapacitors highly rely on the reasonable design of high‐performance electrode materials. Herein, a synergetic strategy of pre‐oxidation and pre‐carbonization is proposed to prepare coal tar pitch (CTP) based porous carbon. The formation mechanism of porous carbon is revealed. Pre‐oxidation increases the heteroatom content and promotes the decomposition of polycyclic aromatic hydrocarbons into small molecules, which is more conducive to improving the subsequent activation and enhancing the microporous specific surface area. Also, the autoclave pre‐carbonization promotes the polymerization of the precursors and increases the carbon yield. Benefiting from the synergistic effect of pre‐oxidation and pre‐carbonation, the obtained carbon exhibits a superior specific capacitance of 365 F g −1 . Meanwhile, ZnCl 2 is used as a hydrogen‐bonding acceptor to synthesize ZnCl 2 ‐EG/PVA deep eutectic solvent (DES) gel, and it is applicable to acidic, neutral, and alkaline electrolytes. The capacitor assembled with the prepared porous carbon and DES gel electrolyte achieves a high energy density of 41.3 Wh kg −1 and works well in unconventional temperatures (−40–75 °C). This work confirms the effect of pre‐oxidation and pre‐carbonization on the fabrication of CTP‐based carbon material and expects to prepare porous carbon using other pre‐oxidation/carbonization agents.