The Polymer Society of Korea

Abstract

While biomass-derived carbons are generally considered non-graphitizable, certain metallic species are known to facilitate the effective conversion of non-graphitizable bio-sourced precursors into highly crystalline graphite. In this study, we demonstrated the graphitization of alginate, a natural polysaccharide extracted primarily from the cell walls of brown seaweed, via this metal-assisted graphitization. The Na+ in sodium alginate was replaced with alkaline earth metal ions (e.g. Ca²⁺, Sr²⁺, Ba²⁺) through ionic crosslinking, followed by thermal treatment at high temperatures (~2400 °C). Pristine sodium alginate produced turbostratic carbon after thermal treatment. In contrast, we confirmed the formation and decomposition of metal carbides within ionically crosslinked alginates during thermal treatment, which played a pivotal role in the development of graphitic layers. The resulting graphitic materials exhibited enhanced lithium-ion battery performance, with Sr²⁺-crosslinked alginate showing the highest crystallinity and a capacity of 347.1 mAh/g. This study confirms that ionically crosslinked alginates are viable biomass precursors for producing graphitic carbon materials suitable for energy storage applications.