Composite Electrodes for Electrochemical Supercapacitors
1 Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L7, Canada
2 Vale Inco Limited, Mississauga, ON, L5K 1Z9, Canada
Nanoscale Research Letters 2010, 5:512-517 doi:10.1007/s11671-009-9518-0Published: 7 January 2010
Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 4–6 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNT) into porous Ni plaque current collectors. Obtained composite electrodes, containing 85% of manganese dioxide and 15 mass% of MWCNT, as a conductive additive, with total mass loading of 7–15 mg cm−2, showed a capacitive behavior in 0.5-M Na2SO4 solutions. The decrease in stirring time during precipitation of the nanofibers resulted in reduced agglomeration and higher specific capacitance (SC). The highest SC of 185 F g−1 was obtained at a scan rate of 2 mV s−1 for mass loading of 7 mg cm−2. The SC decreased with increasing scan rate and increasing electrode mass.