Fabrication of Graphitized Carbon Fibers from Fusible Lignin and Their Application in Supercapacitors

Lignin-based carbon fibers (LCFs) with graphitized structures decorated on their surfaces were successfully prepared using the simultaneous catalyst loading and chemical stabilization of melt-spun lignin fibers, followed by quick carbonization functionalized as catalytic graphitization. This technique not only enables surficial graphitized LCF preparation at a relatively low temperature of 1200 °C but also avoids additional treatments used in conventional carbon fiber production. The LCFs were then used as electrode materials in a supercapacitor assembly. Electrochemical measurements confirmed that LCF-0.4, a sample with a relatively low specific surface area of 89.9 m² g^-1, exhibited the best electrochemical properties. The supercapacitor with LCF-0.4 had a specific capacitance of 10.7 F g^-1 at 0.5 A g^-1, a power density of 869.5 W kg^-1, an energy density of 15.7 Wh kg^-1, and a capacitance retention of 100% after 1500 cycles, even without activation.