Sulfobutylated lignin/polyaniline hybrid as cathode for lithium-ion batteries.

The development of sustainable organic electrode materials is increasingly important for next-generation lithium-ion batteries due to the environmental and resource limitations associated with conventional inorganic cathodes. Lignin, an abundant and under-utilized biomass by-product, offers a promising redox-active platform, but suffers from poor conductivity and structural instability. The sulfobutylated kraft lignin-polyaniline composites (SBLP) were synthesized via oxidative polymerization and systematically characterized using FTIR, TGA, BET, and 1H NMR. This study investigated two formulations with different charge densities, SBLP2.0 and SBLP2.5, to compare their structural and electrochemical properties. Electrochemical evaluation by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and cycling measurements revealed distinct behaviors between the two formulations. SBLP2.5 achieved a high specific capacity of 218 mAh/g, while SBLP2.0 exhibited superior cycling retention (80% retention over 50 cycles) and excellent coulombic efficiency (95%). This proof-of-concept study demonstrates the feasibility of incorporating sulfobutylated lignin into polyaniline-based electrodes, while further studies using a broader range of controlled formulations are required to clarify the role of charge density.