Lignin-Derived Quinone Redox Moieties for Bio-Based Supercapacitors

Abstract

Because of their rapid charging and discharging, high power densities, and excellent cycling life stabilities, supercapacitors have great potential for use in electric vehicles, portable electronics, and for grid frequency modulation. The growing need for supercapacitors that are both efficient and ecologically friendly has generated curiosity in developing sustainable biomass-based electrode materials and electrolytes. Lignin, an aromatic polymer with remarkable electroactive redox characteristics and a large number of active functional groups, is one such candidate for use in renewable supercapacitors. Because its chemical structure features an abundance of quinone groups, lignin undergoes various surface redox processes, storing and releasing both electrons and protons. Accordingly, lignin and its derivatives have been tested as electroactive materials in supercapacitors. This review discusses recent examples of supercapacitors incorporating electrode materials and electrolytes derived from lignin, focusing on the pseudocapacitance provided by the quinone moieties, with the goal of encouraging the use of lignin as a raw material for high-value applications. Employing lignin and its derivatives as active materials in supercapacitor electrodes and as a redox additive in electrolytes has the potential to minimize environmental pollution and energy scarcity while also providing economic benefits.

Recent strides toward transforming lignin into plastics and aqueous electrolytes for flow batteries

“…Recent studies and reviews have concentrated on the electrochemical applications of lignin, such as supercapacitors and electrodes. 21 , 22 , 23 Oxidative depolymerization has been shown to transform lignin into different quinone-like structures, 24 which are key compounds for the electrochemical reactions that take place within a battery. 22 …”

“… 21 , 22 , 23 Oxidative depolymerization has been shown to transform lignin into different quinone-like structures, 24 which are key compounds for the electrochemical reactions that take place within a battery. 22 …”

Controlling stabilization of oil‐in‐water emulsions with lignins through fractionation, functionalization, and formulation

“…Lignocellulosic biomass gives the advantage of being an abundant resource, and its industrial pretreatment allows the separation of lignins, cellulose, and hemicelluloses to use them separately as chemicals 1 . Although the valorization of cellulose and hemicelluloses has been mainly considered and exploited in many fields, such as pharmaceuticals 2 or cosmetics, 3 lignins remain poorly valorized although being the most abundant non‐saccharidic polymer 4 and representing 15%–30% of the organic material in the biosphere 5 . By the use of technical lignins (TL), the sustainability of biorefineries would be increased through the valorization of the whole biomass 6,7 and new multifunctional properties could emerge, differing from other emulsifiers.…”

“…1 Although the valorization of cellulose and hemicelluloses has been mainly considered and exploited in many fields, such as pharmaceuticals 2 or cosmetics, 3 lignins remain poorly valorized although being the most abundant non-saccharidic polymer 4 and representing 15%-30% of the organic material in the biosphere. 5 By the use of technical lignins (TL), the sustainability of biorefineries would be increased through the valorization of the whole biomass 6,7 and new multifunctional properties could emerge, differing from other emulsifiers. Lignins' structure is highly heterogeneous 8 because they are derived from three different monolignol precursors, coniferyl alcohol, sinapyl alcohol, and paracoumaryl alcohol, 9 that undergo oxidative oligomerization, forming various interunit linkages.…”

Dual Action of Lignin: Electrode and Electrolyte for Sustainable Supercapacitor Application

“…On the other side, the presence of abundant active functional groups on the lignin, such as methoxyl, hydroxyl, carbonyl, and carboxyl groups, can take part in charge transfer via the redox chemistry of quinone/hydroquinone, enhancing the performance of supercapacitors. , Due to the non-conductive nature of lignin, it must to be combined with conductive supports of carbon or conducting polymers. For example, a newly designed electrode is prepared by confining lignin with reduced graphene oxide sheets, which display admirable activity due to the synergistic combination of fast reversible charge transfer from the functional groups of lignin and the electron-conducting graphene sheets.…”