Low-Temperature Lignin-Derived Carbon Electrodes Enabled by a Natural Casein Binder for Lithium-Ion, Sodium-Ion Batteries and Supercapacitors

This study presents a novel approach to the use of kraft lignin in electrochemical energy sources, with a focus on its use as anode material. The key novelty of this study is the use of natural casein as an innovative binder in electrode production, offering a sustainable and efficient alternative to conventional binders. The carbonaceous material was obtained from kraft lignin by two heat treatments at a relatively low temperature of 300 °C—one in a nitrogen atmosphere and the other in air. The results indicate that carbonization at this lower temperature provides promising electrochemical properties while improving cost-effectiveness and energy efficiency compared to higher temperature processes. Additionally, wettability analysis based on contact-angle measurements revealed substantially improved electrolyte affinity for casein-based electrodes, which correlates with their enhanced electrochemical performance. The study showed promising performance of the developed electrodes as follows: a capacity of 67 F g−1 for supercapacitor applications, 250 mAh g−1 for lithium-ion batteries, and 50 mAh g−1 for sodium-ion batteries. These results confirm that kraft lignin, in combination with casein as a binder, is an environmentally friendly and economically viable alternative to traditional electrode materials.