Deep Eutectic Solvents Enable Sustainable Fabrication of Lignin-Derived Silicon/Carbon Nanocomposite for High Energy Lithium–Ion Batteries

Lignin is a promising renewable carbon precursor for Si-based anodes, but many lignin-involved fabrication routes require hazardous solvents to dissolve lignin, prepare processable precursor slurries, and coat Si-based particles, which limits the sustainability of these processes. Here, lignin-derived deep eutectic solvents (DESs) were investigated as sustainable lignin-dissolving processing media for Si/C nanocomposite electrode fabrication. In a representative platform, Si nanoparticles were combined with kraft lignin or corn stover lignin (CSL) using DES, followed by thermal treatment to form the negative anode material, which was compared to a N,N-dimethylformamide based process. The results indicate that DES-based fabrication eliminates hazardous solvent use while enhancing long-term electrochemical stability. Notably, the CSL–DES system delivers the most favorable balance between electrochemical accessibility and cycling durability, retaining approximately 1300 mAh g–1 after 200 cycles, highlighting the potential of these DESs for sustainable Si-based anode manufacturing.