A Solvent‐Free Synthesis of Lignin‐Derived Renewable Carbon with Tunable Porosity for Supercapacitor Electrodes

Abstract

Synthesis of multiphase materials from lignin, a biorefinery coproduct, offers limited success owing to the inherent difficulty in controlling dispersion of these renewable hyperbranched macromolecules in the product or its intermediates. Effective use of the chemically reactive functionalities in lignin, however, enables tuning morphologies of the materials. Here, we bind lignin oligomers with a rubbery macromolecule followed by thermal crosslinking to form a carbon precursor with phase contrasted morphology at submicron scale. The solvent-free mixing is conducted in a high-shear melt mixer. With this, the carbon precursor is further modified with potassium hydroxide for a single-step carbonization to yield activated carbon with tunable pore structure. A typical precursor with 90 % lignin yields porous carbon with 2120 m g surface area and supercapacitor with 215 F g capacitance. The results show a simple route towards manufacturing carbon-based energy-storage materials, eliminating the need for conventional template synthesis.

Biowaste-Derived Porous Carbon with Tuned Microstructure for High-Energy Quasi-Solid-State Supercapacitors

“…Even at a rate of 100 A g –1 , HSC-0.50 maintains a capacitance as high as 234 F g –1 (Figures S4b and c), accounting for the superfast rate behavior (83.2% retention). The excellent rate capability is further confirmed by comparison with the results of other HSC- x , YP-50F and recently reported carbons (Figure c and d). ,,− Based on the data in Figure c, C v values of various HSC- x are obtained by using equation (Supporting Information) and plotted in Figure e. As shown, the volumetric capacitance ( C v ) values of HSC-0.50 are the highest at 0.5 and 50 A g –1 , approaching 247.6 and 207.7 F cm –3 , respectively.…”

Transforming lignin into porous graphene via direct laser writing for solid-state supercapacitors

“…Template-free and solvent-free methods can simplify fabrication, but still require prolonged high-temperature treatment, like pyrolysis. 12,13 The drawbacks with current methods would hinder low cost, mass production of lignin-derived electrode materials. Therefore, a simple, green, and low-cost route for lignin upgrading into carbon-based electrode materials is highly desired.…”

Ultrafast-Freezing-Assisted Mild Preparation of Biomass-Derived, Hierarchically Porous, Activated Carbon Aerogels for High-Performance Supercapacitors

“…Lignin-derived CAs have been prepared by various methods, such as formation of lignin aerogels via electrospinning or use of templates followed by carbonization. − Among these methods, ice-segregation-induced self-assembly (ISISA) is a facile method to produce lignin aerogels. ISISA involves freezing as an essential step, and the freezing rate, temperature gradient, solute concentration, and molecular weight greatly affect the morphology of the ice crystal templates .…”