Honeycomb-like N/O self-doped hierarchical porous carbons derived from low-rank coal and its derivatives for high-performance supercapacitor

•N/O self-doped HPCs were successfully prepared from several coal derivatives.•The HPCs own honeycomb-like hierarchical porous structure with ultrahigh SSA.•The HPC from SPLRL has specific capacitance of 373 F g−1 at 0.5 A/g.•The assembled supercapacitors exhibit high energy density and power density.•The relationship between precursor composition and supercapacitor performance was revealed.