Coal-derived N,O co-doped mesoporous carbon as electrode material for high performance aqueous electric-double layer capacitors and zinc-ion hybrid supercapacitors

Carbon-based materials are widely used as electrode materials for electrochemical energy storage devices. However, achieving high performance carbon materials via facile preparation process with abundant precursors is still a huge challenge. Herein, a nitrogen/oxygen co-doped mesoporous coal-derived carbon (N/O-DMCC) is synthesized with raw coal as precursor through a facile pyrolysis treatment. The treatment endows the N/O-DMCC with high surface area, mesoporous structure, as well as rich heteroatom doping content. The combination of above features enhances the electrochemical capacitance of the as-synthesized N/O-DMCC by delivering a satisfactory value of 376.5 F g−1 (i.e., 376.5 C g−1) at 0.5 A g−1, which is superior to many state-of-the art coal-derived carbon materials in literature. A symmetric electric-double layer capacitor (EDLC) and a zinc-ion hybrid supercapacitor (ZHS) based on N/O-DMCC electrode are assembled to achieve high energy densities of 23.1 Wh kg−1 (at 500 W kg−1) and 347.0 Wh kg−1 (at 175.5 W kg−1), respectively, strongly demonstrating the huge potential of coal-derived carbon materials for energy storage devices.