Lignin-based Carbon Fibers

Abstract

An overview of the production of carbon fibers based on lignin is presented. The structure, isolation, and properties of lignin are first discussed in the context of their effects on carbon fiber production. A general overview of carbon fiber manufacturing is then presented to provide background for a discussion of previous and current research on lignin-based carbon fiber. Current research on fiber spinning, thermostabilization, and carbonization of lignin is reviewed and directions for future research are discussed. Finally, emerging new opportunities for lignin-based carbon fiber in non-structural applications are presented, highlighting recent research from our laboratory on the production of sub-micron and nanometer scale carbon fibers by electrospinning of lignin. IntroductionCarbon fibers (CFs) are rather unique materials which can simultaneously display high tensile strength (up to ∼7 GPa), high tensile modulus (up to 900 GPa), and low density (ρ = 1.75-2.00 gcm −3 ). 1 These properties make CF an ideal reinforcement material in high-strength, lightweight composite materials used in aerospace, automotive, marine, and sporting goods applications. 1−4 The electrical, thermal, and surface properties of CF can also be engineered to exhibit different characteristics, making them useful as adsorbents, 5 catalyst supports, 6 biomedical materials, 7 electromagnetic shielding, 8 and in other electrical applications 8 such as electrical double-layer capacitors (EDLCs) for energy storage or capacitive deionization, 9−14 Li + -ion batteries, 15−17 fuel cells, 18,19 and dye-sensitized solar cells. 20 Unfortunately, high cost is an obstacle to large-scale implementation of CFs and their composites for automotive and energy applications. The dominant precursor for CF today are synthetic poly(acrylonitrile) (PAN)-based copolymers. PAN precursor costs have been reported to account for approximately half of the manufacturing cost of high-performance CF, which was reported to be in the range of ∼US$12.25 to US$30/kg. 21 Replacement of PAN with lower-cost precursors could expand the range of applications for CF.

Green Carbon Nanofiber Networks for Advanced Energy Storage

“…16 However, despite its great abundancy and easy accessibility in nature, lignin has been highly underutilized for decades. 17 There is more than 50 million tons of lignin produced annually by the pulping and paper-making process, but most of it is burned for low-value thermal energy. 18−20 Although significant efforts have been made to advance the production of lignin-based materials and applications, as of today only <2% of the produced lignin is valorized and used for example in adhesives and foaming agents.…”

“…Lignin is the second most abundant natural polymer on earth, and together with cellulose and hemicellulose, lignin is one of the main components in wood . However, despite its great abundancy and easy accessibility in nature, lignin has been highly underutilized for decades . There is more than 50 million tons of lignin produced annually by the pulping and paper-making process, but most of it is burned for low-value thermal energy. − Although significant efforts have been made to advance the production of lignin-based materials and applications, as of today only <2% of the produced lignin is valorized and used for example in adhesives and foaming agents. − It is also believed that making good use of lignin will enable a biofuel economy to be competitive with oil refining as lignin is now only a low-value byproduct in the biorefinery. ,, Excitingly, because of the merits of low price, high carbon content, and no toxic emission during the process, lignin can be a fascinating raw material for the production of high-quality biocarbons with well-tailored functions and properties. ,,, …”

Investigation of Structure and Chemical Composition of Carbon Nanofibers Developed From Renewable Precursor

“…Carbon fibers are mostly prepared from the fossil-based polymer polyacrylonitrile (PAN) or mesophase pitch; nonetheless, researchers and industrial manufacturers are actively seeking for renewable, low-cost, and environmentally friendly replacements for PAN-based precursors (Baker and Rials, 2013). Lignin, the second most abundant biopolymer, is attracting considerable attention because of its high carbon content and dominant aromatic structure, which are beneficial for its conversion into carbon fibers (Dallmeyer and Kadla, 2014).…”