Sustainable PAN-lignin/CoFe2O4 composite nanofibers as high-performance anode materials for lithium-ion batteries: synthesis, characterization, and electrochemical evaluation

Abstract

This study presents the development of sustainable composite electrodes combining polyacrylonitrile (PAN)-lignin carbon nanofibers with cobalt ferrite (CoFe2O4) nanoparticles for advanced lithium-ion battery anodes. The composite materials were fabricated via centrifugal spinning followed by controlled carbonization at 800 degrees C under argon atmosphere. Comprehensive characterization using X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of amorphous carbon structures with localized graphitic ordering and well-crystallized CoFe2O4 spinel phase. The carbonized fibers exhibited uniform morphology (582 nm-1.09 mu m diameter) with interconnected porous structures favorable for electrochemical applications. Electrochemical performance was systematically evaluated for composite electrodes containing 0%, 25%, 50%, and 75% CoFe2O4 loadings through galvanostatic charge-discharge testing, cyclic voltammetry, and electrochemical impedance spectroscopy. The optimal composition (25% CoFe2O4) demonstrated exceptional performance with an initial discharge capacity of 800 mAh g-1 at 0.05 A g-1, maintaining 250 mAh g-1 after 6 cycles. At higher current density (0.5 A g-1), this electrode delivered 400-450 mAh g-1 initially and retained 100 mAh g-1 after 50 cycles, significantly outperforming pure PAN-lignin electrodes (100-150 mAh g-1 initial, degrading to 25 mAh g-1). The superior performance stems from synergistic effects between the lignin-derived carbon matrix providing structural stability and the electrochemically active CoFe2O4 enhancing lithium storage capacity through conversion reactions. This work successfully demonstrates an environmentally sustainable, high-performance anode material that addresses critical limitations of conventional graphite electrodes while maintaining competitive electrochemical characteristics for practical lithium-ion battery applications.