Conductive Carbon Microfibers Derived from Wet-Spun Lignin/Nanocellulose Hydrogels

We introduce an eco-friendly process to dramatically simplify carbon microfiberfabrication from biobased materials. The microfibersare first produced by wet-spinning in aqueous calcium chloride solution, which provides rapid coagulation of the hydrogel precursors comprising wood-derived ligninand 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)- oxidized cellulosenanofibrils (TOCNF). The thermomechanical performance of the obtained lignin/TOCNF filaments is investigated as a function of cellulose nanofibril orientation ( wide angle X-ray scattering(WAXS)), morphology (scanning electron microscopy (SEM)), and density. Following direct carbonization of the filaments at 900 °C, carbon microfibers(CMFs) are obtained with remarkably high yield, up to 41%, at ligninloadings of 70 wt % in the precursor microfibers(compared to 23% yield for those produced in the absence of lignin). Without any thermal stabilization or graphitization steps, the morphology, strength, and flexibility of the CMFs are retained to a ...