Polyaniline wrapped manganese dioxide nanorods: Facile synthesis and as an electrode material for supercapacitors with remarkable electrochemical properties

Abstract

Conducting polymers and transition metal oxides are good electrodes for supercapacitors owing to their high charge storage characteristics. Different techniques have been utilized in fabricating novel nanocomposites of polyaniline (PANI) and manganese dioxide (MnO2) for capacitance enhancement. Herein, we report a facile approach towards the control of core/shell architecture of MnO2 nanorods and PANI, respectively, via in-situ hydrothermal polymerization method. Structure and morphology of the PANI wrapped MnO2 nanorods (MnO2@PANI) were properly characterized and their capacitance enhancement was explored carefully. The experimental results revealed that the specific capacitance of MnO2@PANI40 (40% MnO2 relative to aniline monomer) nanocomposite is 665 F g-1 at a current density of 1 A g-1, higher than that of pristine MnO2 (273 F g-1) and pristine PANI (434 F g-1). Moreover, 82% of the original capacitance of the nanocomposite is retained after 1500 consecutive CV cycles at a scan rate of 100 mVs−1, which is far higher than the stability of pristine PANI (48%). Excellent electrochemical performance of the MnO2@PANI40-based electrode is attributed to the synergistic effect of the core/shell networked hierarchical structure of the nanocomposite. The unique structure improves the ion transportation efficiency and reduces the ion diffusion path and the uniform coating of PANI offers protection against the dissolution of MnO2 in the acidic electrolyte. Furthermore, high electrical conductivity status of PANI (due to its half oxidation-half reduction status, justified by XPS test) plays an important role in the capacitance enhancement of the nanocomposite.