수퍼커패시터용 망간옥사이드 전극의 전기화학적 특성

Electrochemical Properties of Manganese Oxide Electrode for Supercapacitor

Amorphous $MnO_{2}{\cdot}nH_{2}O$ in 1M KOH aqueous electrolyte proves to be an excellent electrode for a faradic electrochemical capacitor cycled between -0.5 and +1.0 versus Ag/AgCl. The effect of thermal treatment on the crystalinity, particle structure, and corresponding electrochemical properties of the resulting xerogel remained amorphous as Mn(OH)2 up to 160$^{\circ}C$. With an increase in the temperature above 200$^{\circ}C$, both the surface area and pore volume decreased sharply, because the amorphous Mn(OH)2 decomposed to form MnO that was subsequently oxidized to form crystalline Mn3O4. In addition, the changes in the crystallinity, and particle structure all had significant but coupled effects on the electrochemical properties of the xerogels. A maximum capacitance of 160.6F/g was obtained for an electrode prepared with the MnOx Xerogel calcined at 150$^{\circ}C$, which was consistent with the maxima exhibited in both the surface area and pore volume. This capacitance was attributed solely to a surface redox mechanism.