Lignin Nanoparticles as Charge Storage Centers in Organic Battery Electrodes

Abstract

Lignin, the second most abundant biopolymer on Earth, has recently emerged as a promising redox-active material for organic batteries. Different types of lignin have been explored but inherent challenges have remained, i.e., the difficulties of processing kraft lignin and the low charge storage capacity retention of lignosulfonate due to its high water-solubility. In this work, we propose the use of an alternative candidate, lignin nanoparticles (LNPs), which are insoluble, but colloidally stable dispersions in aqueous media, which, can be easily processed using different manufacturing techniques. By combining LNPs with a conducting polymer (PEDOT:PSS), we have successfully prepared a composite that has a charge storage capacity of up to 42.5 mAh/g at a current density of 1 A/g, while its capacity retention shows a good improvement (70% after 1000 cycles) in comparison to the similar systems of lignosulfonate-based electrodes. The morphology and chemical structure of LNPs are tunable, therefore, the effects of particle sizes and the preparation methods of LNPs on the electrode performance were also studied. With the obtained results, this work suggests LNPs as promising materials for the preparation of green and low-cost lignin-based energy storage devices. Keywords: Lignin nanoparticles, Organic batteries, PEDOT:PSS, Electrochemistry.