Polyaniline combining with ultrathin manganese dioxide nanosheets on carbon nanofibers as effective binder-free supercapacitor electrode

The binder-free supercapacitors were fabricated from polyaniline (PANI)@MnO2@flexible carbon nanofibers (CNFs) composite flexible electrodes. The flexible electrodes were constructed using a layer-by-layer synthetic strategy: a large-area MnO2 ultrathin nanosheets firstly grew onto the surface of CNFs by self-decomposition of KMnO4, and then the PANI was in-situ coated on MnO2 ultrathin nanosheets in turn through a dilute-solution polymerization to form PANI@MnO2@CNFs ternary electrode. In PANI@MnO2@CNFs electrode, the two-dimensional sheet-like structure provided by the PANI@MnO2 nanosheets could be served as a high specific surface area and electrically conductive network for fast transport of electrolyte ions and electrons in the re-action, where PANI and MnO2 were high-performance supercapacitor electrode materials. The specific capaci-tance of single PANI@MnO2@CNFs electrode was 654 F/g at the scan rate of 10 mV/s in Na2SO4 electrolyte, and the capacitance retention was about 88.8% after 1000 cycles. Furthermore, the as-prepared symmetric super-capacitor with a PVA/Na2SO4 gel electrolyte exhibited the maximum energy density of 27.9 Wh/kg at the power density of 400 W/kg, which was superior or similar to previously reported values of PANI-based supercapacitor. The as-prepared supercapacitors exhibited good electrochemical performance and high flexibility, which was a meaningful exploration for the application of flexible electrodes in the production of multi-element electrode materials for supercapacitors.