Electrochemical properties of nanosized hydrous manganese dioxide synthesized by a self-reacting microemulsion method

摘要

Manganese dioxide has been synthesized by a new simple self-reacting microemulsion method. The synthesized MnO_2 has been found to be amorphous structure containing a moderate amount of water by X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. Particles in a spherical shape with about 4 nm in diameter have been observed by transmission electron microscopy. Cyclic voltammetic tests have been performed between -0.5 and 0.5 V versus Hg/Hg_2SO_4 in 1 mol L~(-1) Na_2SO_4 solution at sweep rates up to 50 mVs~(-1). A specific capacitance value as high as 246.2 F g~(-1) was obtained, which was much higher than 146.5 F g~(-1) of MnO_2 prepared by chemical co-precipitation. After 600 cycles, only 6% decrease of specific capacitance was measured which indicated that such a material possesses good cycling property.