Korean Journal of Materials Research ISSN:1225-0562(Print) 2287-7258(Online) 한국재료학회지

MnO₂ can be potentially utilized as an electrode material for redox capacitors. The deposition of MnO₂ with poor electrical conductivity onto porous carbons supplies them with additional conductive paths; as a result, the capacitance of the electrical double layer formed on the porous carbon surface can be utilized together with the redox capacitance of MnO₂. However, the obtained composites are not generally suitable for industrial production because they require the use of expensive porous carbons and/or inefficient fabrication methods. Thus, to develop an effective preparation procedure of the composite, a suitable structure of porous carbons must be determined. In this study, MnO₂/C composites have been prepared from activated carbon gels with various pore sizes, and their electrical properties are investigated via cyclic voltammetry. In particular, mesoporous carbons with a pore size of around 20 nm form a composite with a relatively low capacitance (98 F/g-composite) and poor rate performance despite the moderate redox capacitance obtained for MnO₂ (313 F/g-MnO₂). On the other hand, using macro-porous carbons with a pore size of around 60 nm increases the MnO₂ redox capacitance (399 F/g-MnO₂) as well as the capacitance and rate performance of the entire material (203 F/g-composite). The obtained results can be used in the industrial manufacturing of MnO₂/C composites for supercapacitor electrodes from the commercially available porous carbons.