Synthesis and electrochemical performance of polyaniline–MnO2 nanowire composites for supercapacitors

Polyaniline–MnO2 nanowire (PANI–MNW) composites were prepared by in situ chemical oxidative polymerization of aniline monomer in a suspension of MnO2 nanowires. The structure and morphology of the PANI–MNW composites were characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). Their electrochemical properties were investigated using cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy in 1 mol/L KOH electrolyte. The PANI–MNW composites show significantly better specific capacity and redox performance in comparison to the untreated MnO2 nanowires. The enhanced properties can be mainly attributed to the composite structure wherein high porosity is created between MnO2 nanowires and PANI during the process of fabricating the PANI–MNW nanocomposites. A specific capacitance as high as 256 F/g is obtained at a current density of 1 A/g for PANI–MNW–5, and the composite also shows a good cyclic performance and coulomb efficiency.

► Polyaniline–MnO2 nanowire (PANI–MNW) composites were prepared. ► PANI–MNW exhibited good electrochemical performance. ► A specific capacitance of 256 F/g was measured at 1 A/g. ► PANI–MNW showed significantly better specific capacity than MnO2 nanowires. ► The enhanced capacitances were attributed to the porous structure of PANI–MNW.