Self‐template synthesis of hierarchical porous carbon for supercapacitors based on bituminous coal

Abstract

We develop a unique self-template method to synthesize hierarchical porous carbons (HPCs) by co-activation of heavy component (HC) and dense medium component (DMC) separated from bituminous coal. HC and DMC are obtained by employing the mixture solvent (CS2/N-methyl-2-pyrrolidone) and deionized water as extractant and back extractant to separate bituminous coal. The plentiful kaolinite [Al2(Si2O5) (OH)4] in the HC produce Natrolite (K) (K2Al2Si3O10•2H2O) during the activation process, which can serve as self-template to prepare HPCs. Moreover, the addition of asphalt-like DMC allows the templates to be better utilized. Effect of the remixture ratio of DMC/HC on HPCs' porous structures and electrochemical properties are studied in detail. The optimal sample (HPC-0.4) displays an ultrahigh surface area (3851 m2 g−1), appropriate hierarchically system and excellent conductivity. When applied to supercapacitors, HPC-0.4 delivers a large capacity of 436 F g−1 at 0.1 A g−1 in alkaline electrolyte, and maintains 212 F g−1 at 10 A g−1. This self-template strategy paves a practical route to construct applicable porous carbons for supercapacitors from low-cost high-minerals coal.