Electrospun Lignin-Derived Carbon Micro- and Nanofibers: A Review on Precursors, Properties, and Applications

The development of advanced engineering materials from low-cost renewable or waste resources is a key aspect of sustainability. Carbon nanofibers (CNFs) are a one-dimensional form of carbon with diameters in the submicron- and in the nanometer range with wide applicability in energy storage, catalysis, and adsorption. Lignin has recently emerged as a low-cost, biorenewable precursor for the production of CNFs. This comprehensive review presents the state-of-the-art of the manufacture of CNFs from lignin via the electrospinning technique. The first part of this review is concerned with the properties of lignin, the structure and applications of CNFs, especially for energy storage, and the description of the electrospinning method. The second part is focused on the different lignin-based precursor formulations for the manufacture of electrospun CNFs. These include the use of lignin alone or blended with other polymers at various mass ratios (polyacrylonitrile, poly(vinyl alcohol), poly(ethylene oxide), cellulose acetate, poly(ethylene terephthalate), and polyvinylpyrrolidone). In addition, different manufacturing approaches and strategies aiming to enhance the textural, mechanical, and electrochemical properties of CNFs are discussed in connection with their performance in relative applications.