Hierarchical porous carbon materials produced from heavy bio-oil for high-performance supercapacitor electrodes

•Hierarchical porous carbon was produced from heavy bio-oil simply and economically.•Prepared carbon has specific surface area of 2826 m2 g−1 with rich micro-mesopores.•Specific capacitance in three-electrode system reached 287 f g−1 at 0.5 a g−1.•Aqueous symmetric capacitor has high energy density of 12.95 W h kg−1 at 300 W kg−1.•Heavy bio-oil proved to be an ideal carbon source beyond raw biomass structure.