Electrospun lignin-derived carbon nanofiber mats for sustainable vanadium redox flow battery electrodes

Carbon nanofiber mats derived from renewable resources are gaining attention as sustainable alternatives to conventional synthetic precursors for energy storage applications. Redox flow batteries are a promising solution for large-scale energy storage, facilitating the integration of renewable energy into the grid. However, the efficiency of these batteries is often limited by conventional carbon felts or papers, which suffer from poor electrocatalytic activity, hindering their potential for grid-scale applications. In this study, alkali lignin, a biopolymer rich in aromatic structures, was employed as the primary carbon source for the fabrication of carbon nanofiber mats via electrospinning, aimed at application in vanadium redox flow batteries (VRFBs). Polyvinylpyrrolidone (PVP) was incorporated as a binder polymer to enhance the electrospinnability of the lignin solution using stationary needle-based electrospinning techniques. The electrospun mats underwent thermal stabilisation and carbonisation to yield conductive carbon nanofibers. A comprehensive analysis of the morphological and elemental evolution of the nanofibers throughout the processing stages was conducted using scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray (EDX). The results demonstrate that lignin-based carbon nanofibers possess favourable characteristics such as interconnected morphology, adequate carbon yield, and structural integrity, making them promising electrode candidates for sustainable VRFB systems. This study underscores the potential of biomass-derived polymers in advancing the development of next-generation carbon electrodes for large-scale energy storage.