Wool fiber-derived nitrogen-doped porous carbon prepared from molten salt carbonization method for supercapacitor application

Transformation of biomass into nitrogen-doped carbon materials has been considered as effective and affordable route for energy generation and conversion. Wool fiber, as an abundant renewable biomass, contains plentiful nitrogen and sulfur element. Here, nitrogen-doped porous carbon derived from wool fiber by molten salt carbonization method has been realized in 700 °C LiCl/KCl/KNO3 melt. The wool fiber-derived carbon via molten salt carbonization (WFC-MSC) with honeycomb-like structure has a specific surface area of 787.079 m2 g−1 as well as a nitrogen content of 2.6 wt%. Using this nitrogen-doped carbon as electrode materials for supercapacitor, high specific capacitance of 318.2 F/g at 0.25 A/g and good high-rate capability are achieved. The stable cycling performance with specific capacitance of 210 F/g after 5000 cycles at 5 A/g is realized. Moreover, WFC-MSC-based symmetric supercapacitor possesses high specific energy of 20.2 Wh kg−1 with a power density of 202 W kg−1 operated a wide voltage range of 1.8 V in aqueous neutral Na2SO4 electrolyte. These results highlight the merits of the molten salt carbonization of wool fiber in producing nitrogen-doped porous carbon and suggest its prospect for application in supercapacitors.