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.