Sustainable nitrogen-containing hierarchical porous carbon spheres derived from sodium lignosulfonate for high-performance supercapacitors

Nitrogen-containing carbon sphere with hierarchical porous structure is obtained through a facile thermostabilization and carbonization method of biomass-derivative sodium lignosulfonate. The synthesis route we proposed is cost-effective and environment-friendly without additional nitrogen precursor, activation or templating agent. The as-prepared carbon spheres exhibit high specific surface area of 1255–1939 m2 g−1 and moderate surface nitrogen content of 1.14–1.66 at.%. When assembling into supercapacitors with 7 M KOH aqueous solution as electrolyte, the carbon sphere shows superior gravimetric specific capacitance up to 276 F g−1 at 0.1 A g−1, high gravimetric energy density of 7.8 Wh kg−1 and power density of 6.2 kW kg−1, together with unprecedented cycling stability (99.5% capacitance retention after 10000 cycles). Notably, in 1 M SBPBF4/PC organic electrolyte, the carbon sphere based supercapacitor presents impressive gravimetric energy density of 34.3 Wh kg−1 and power density of 9.4 kW kg−1. These outstanding electrochemical performances suggest that the as-prepared porous carbon spheres should be a promising candidate for the field of energy storage.