Processing–Structure–Property Relationships for Lignin‐Based Carbonaceous Materials Used in Energy‐Storage Applications

Abstract

Lignin, an abundant organic polymer and a byproduct of pulp and biofuel production, has potential applications owing to its high carbon content and aromatic structure. Processing–structure relationships are difficult to predict because of the heterogeneity of lignin. This work discusses the roles of unit operations in the carbonization process of softwood lignin, and their resulting impacts on the material structure and electrochemical properties in application as the anode in lithium‐ion cells. The processing variables include the lignin source, temperature, and duration of thermal stabilization, pyrolysis, and reduction. Materials are characterized at the atomic and microscales. High‐temperature carbonization, at 2000 °C, produces larger graphitic domains than at 1050 °C, but results in a reduced capacity. Coulombic efficiencies over 98 % are achieved for extended galvanostatic cycling. Consequently, a properly designed carbonization process for lignin is well suited for the generation of low‐cost, high‐efficiency electrodes.

Are lignin-derived carbon fibers graphitic enough?

“…However, there is an emerging field of research targeting the development of new methods to convert lignin and other bioresources into graphite for electrochemical applications, such as anodes for Li-ion batteries. 35,[38][39][40][41][42][43][44][45] The lignin graphitization procedures used in these studies are similar to those used in carbon fiber studies, with the major exception being that strength properties are not optimized since electrode applications do not require such. Instead, lignin graphitization studies optimize for graphitic structure formation, and usually small graphitic particles are produced, not fibers.…”

“…8) prepared carbon materials from kraft lignin for use in energy storage applications. 42 The kraft lignin underwent an initial carbonization at 1000°C under nitrogen gas, 18,46 Plots are from a publicly available presentation given by the US Dept. of Energy.…”

“…Similar to Köhnke et al's work, 38 Banek et al started with lignin of very small particle size. Garcia-Negron et al also used small particles for high temperature graphitization, 42 but obtained less graphitic materials than Köhnke and Banek. One possible reason for the discrepancy in results among the papers is that Köhnke and Banek reduced the particle size of raw lignin prior to any thermal treatment, whereas Garcia-Negron reduced particle size after an initial carbonization at 1000°C.…”

In Situ‐Derived Porous SiO2/Carbon Nanocomposite from Lichens for Lithium‐Ion Batteries

“…Among the numerous carbon materials, biochar is of particular interest because of its low cost and material consistency, which can be realized from abundant and nontoxic biomass precursors . Various precursors, such as lignin, pomelo pericarp, rice husk, litchi shells, and peanut shells, have been used to prepare biochar, which was commonly carbonized at 500–900 °C under argon atmosphere and followed by acid or alkaline‐washing to remove the impurities, and then applied in LIBs as high‐capacity electrode materials . Thus, the fabrication of SiO 2 /carbon composite will be a highly attractive idea.…”

Electrically-Conductive Sub-Micron Carbon Particles from Lignin: Elucidation of Nanostructure and Use as Filler in Cellulose Nanopapers

“…A high specific surface area may be obtained by the electrospinning of lignin-containing aqueous solutions [22,25,30,31,32,33,34] or from particulate lignin [35,36,37,38,39], both of which can be carbonized. Potential applications of this class of materials lie predominantly in electrochemistry and filtration [7,20,40,41].…”