Carboxylated multi-walled carbon nanotube/polyaniline composites for high-performance supercapacitor electrodes

Multi-walled carbon nanotube (MWCNT)/polyaniline (PANI) composite and carboxylated multi-walled carbon nanotube (MWCNT-COOH)/PANI composites are fabricated via in situ chemical oxidative polymerization method. The crystallinity, chemical structure and morphology of the composites are investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and field-emission scanning electron microscopy (FESEM), respectively. Based on the different morphology, the formation mechanism of the composites is proposed and the influence of the morphology on the electrochemical performance is predicted. The electrochemical properties of the composites are evaluated by galvanostatic charge/discharge (GCD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The MWCNT-COOH/PANI composite electrode shows higher specific capacitance than that of the MWCNT/PANI composite, as can be ascribed to the interpenetrating network structure of the MWCNT-COOH/PANI composite and the co-doping of DBSA and MWCNT-COOH. The MWCNT-COOH/PANI composite with 15% MWCNT-COOH presents the best electrochemical performance owing to the synergistic and comprehensive effect of the components. Using functionalized MWCNT provides an efficient approach to prepare high-performance composite materials for electrical energy storage fields.