Lignin as a sustainable precursor for electrodes and electrolytes of emerging supercapacitors

Abstract

Lignin, an affordable renewable bioresource, is one of the most abundant naturally existing polymers, popular for its high carbon content and rich functional groups. Recently, advances in science and technology have unveiled the advantages of using lignin in the design of novel and emerging energy storage devices. In this review, we present the specific roles of lignin in the development of active materials for the electrodes and electrolytes of supercapacitors. The first section covers a brief introduction to lignin chemistry, functional groups, and classical isolation techniques. We then discuss the merits of lignin as an active material for electrodes and electrolytes featuring different material development approaches and novel device fabrication techniques. Towards emerging wearable electronics, we also highlight the mechanical and electrochemical performance of representative studies on traditional and flexible supercapacitors using lignin precursors. Beyond the lab, we conclude by summarizing the major challenges and prospective directions toward achieving the commercialization of lignin-based supercapacitors.