Application of a novel redox-active electrolyte in MnO2-based supercapacitors

This paper reports a novel strategy for preparing redox-active electrolyte through introducing a redox-mediator (p-phenylenediamine, PPD) into KOH electrolyte for the application of ball-milled MnO2-based supercapacitors. The morphology and compositions of ball-milled MnO2 were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical properties of the supercapacitor were evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques. The introduction of p-phenylenediamine significantly improves the performance of the supercapacitor. The electrode specific capacitance of the supercapacitor is 325.24 F g(-1), increased by 6.25 folds compared with that of the unmodified system (44.87 F g(-1)) at the same current density, and the energy density has nearly a 10-fold increase, reaching 10.12 Wh Kg(-1). In addition, the supercapacitor exhibits good cycle-life stability.