Synthesis of γ -MnO ₂ /PANI Composites for Supercapacitor Application in Acidic Electrolyte

In this paper, γ -MnO ₂ was prepared via simple hydrothermal method and chosen to compound γ -MnO ₂ /polyaniline (PANI) composite electrode by in situ polymerization. The electrochemical performances of as-prepared samples were explored in acidic and neutral medium, respectively. And influenced its effects such as the different additions of composites, scan rates, and current densities in 0.5 M H ₂ SO ₄ electrolyte were further investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS), respectively. The good capactive behaviours indicated that the γ -MnO ₂ in the conductive matrix of PANI restrains them from dissolution in acidic electrolyte, and PANI itself affords an additional electrochemical activity to the composite. A asymmetric supercapacitor was fabricated using γ -MnO ₂ /PANI as the positive electrode and activated carbon (AC) as the negative electrode. It displayed good capacitance performance of 232.1 F g ⁻¹ and high energy density 66.4 Wh kg ⁻¹ at a power density of 350.1 W Kg ⁻¹ , as well as good cycling life (maintaining 78.65% initial capacitance after 3000 cycles). The enhanced electrochemical performances implie that the γ -MnO ₂ /PANI composite can be potentially applied in superca-pacitors.