Carbon fibers derived from pure alkali lignin fibers through electrospinning with carbonization

Alkali lignin (AL) fibers with a smooth surface and fine morphological appearance were successfully produced via electrospinning using a simple heated single spinneret system, instead of typical electrospinning of lignin with added synthetic polymer blends or conventional co-axial electrospinning. To reduce the size of the fibers, glycerol was added to the spinning solution as a co-solvent for surface tension reduction and electrospinnability improvement. After electrospinning, stabilization and carbonization were subsequently performed to convert AL fibers to carbon fibers (CFs). The obtained CFs displayed rough and uneven surfaces. However, the CFs derived from glycerol-added solution showed greater electrical conductivity, specific surface area, and porosity compared with those from pure AL solution. Furthermore, the results indicated that the inorganic salts on the rough surface of CFs were successfully removed by sulfuric acid (H2SO4) washing. After H2SO4 washing, the CFs revealed a smoother surface and higher electrical conductivity, specific surface area, and porosity.