Facile synthesis of γ-MnO2/rice husk-based-activated carbon and its electrochemical properties

Abstract

In this study, composite [Formula: see text]-MnO2/activated carbon (AC) was prepared by chemical deposition method, and then it was assembled into electrode and electrochemical capacitor. Effects of reaction temperature and MnO2 content were studied. Materials were characterized by X-ray diffraction, scanning electron microscope and electrochemical test. MnO2 prepared at 30[Formula: see text]C was amorphous, and it displayed the high specific capacitance as nearly four times as MnO2 at 80[Formula: see text]C. Due to MnO2 particles which would block carbon pores when its content was too high, the composite containing 30% of MnO2 exhibited the largest specific capacitance of 278.3[Formula: see text]F/g at 0.2[Formula: see text]A/g in K2SO4 electrolyte. The equivalent series resistance and charge transfer resistance of material were only 1.35[Formula: see text][Formula: see text] and 1.41[Formula: see text][Formula: see text], respectively. After 1000 cycles, the capacitance retention was still 91.6%. It indicated that chemical deposition was a facile, low cost and effective method to prepare MnO2/AC with good electrochemical performances.