High performance all lignin derived supercapacitors for energy storage applications

Abstract

The development of next-generation sustainable energy storage devices is attracting a lot of attention. This study explores the potential use of lignin, a biopolymer typically considered a byproduct of the paper and pulp industry, as a starting material for producing hydrogels through chemical crosslinking. The resulting hydrogels are then evaluated for their efficacy as precursors for electrolyte and electrode preparation in the development of a supercapacitor. Several concentrations of lignin and crosslinker were evaluated to determine the optimal conditions for producing hydrogel electrolytes. The optimised hydrogels exhibited excellent properties, including high swelling capacity, an interconnected macroporous morphology, and structural integrity. The carbonisation of lyophilised lignin hydrogels produced lignin-derived carbon materials with tailored nanoporous honeycomb-like structures. The integration of chemically crosslinked lignin hydrogel electrolytes with lignin-derived carbon electrodes resulted in a sustainable supercapacitor with superior electrochemical properties. The resulting all-lignin-based supercapacitors demonstrated a capacitance of 40.7 F/g at 0.5 A/g current density, with a capacity retention of 60% at higher current densities. The results of this study highlight the promise of lignin-based materials as both electrodes and electrolytes for the creation of environmentally sustainable, high-performance supercapacitors.