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

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.