Lignin based carbon fiber fabrics with hybrid doping approach as self-standing electrodes for supercapacitors

Novel carbon fiber (CF) mats were fabricated from tobacco leaf-based carbon dots (TL-CDs) filled rubber wood chip-extracted lignin (RWC-L)/polyacrylonitrile (PAN) composite fibers with a hybrid doping method. The ex -situ doping was applied during fiber formation via electrospinning by adding functionalized TL-CDs in the spinning solution. The in-situ doping was carried out in carbonization process for nitrogen (N) and oxygen (O) atom generation by utilizing RWC-L and PAN as a mixed precursor. The CF properties and electrochemical performances were evidently influenced by TL-CD content and carbonization temperature. The CF fabric con-taining 0.4% w/v of TL-CDs and carbonized at 1200 degrees C provided optimal specific capacitance (Cs -225 F g-1), energy density (ED -53 W h kg -1), and power density (PD -130 W kg -1) at a current density of 0.2 A g-1 in 6 M KOH electrolyte. It also had excellent cycling stability of -90% after 12,000 cycles at a current density of 5 A g-1. This could be combined effects of a small fiber diameter (-0.65 mu m), a high heteroatom content (-21 wt % of N and O atoms), a large surface area (-1063 m2 g-1), a high micropore volume (-2.41 cm3 g-1), high graphitic carbon (ID/IG ratio -0.97), and high electrical conductivity (-62 S cm -1). Moreover, the electro-chemical properties of the TL-CD added CF sheet were superior to those of the bare CF mat. Therefore, this work introduces a sustainable and efficient approach to develop lignin-based CF fabrics as self-standing electrodes for advanced energy-storage devices.

Automated summary

A novel carbon fiber mat was developed by combining tobacco leaf-based carbon dots with rubber wood chip-extracted lignin/polyacrylonitrile composite fibers. The performance of the carbon fiber was found to be influenced by the carbon dots content and carbonization temperature. The carbon fiber mat containing 0.4% volume concentration of tobacco leaf-based carbon dots and carbonized at 1200℃ exhibited optimal specific capacitance (225 F g-1), energy density (53 W h kg-1), and power density (130 W kg-1) at a current density of 0.2 A g-1 in 6 M KOH electrolyte, with cycling stability of 90% after 12,000 cycles at a current density of 5 A g-1.