Abstract
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.
Highlights
Porous Ni materials, such as plaques [1] and foams [2], are widely used in industry for the fabrication of electrodes for rechargeable batteries
Manganese dioxide nanofibers with length ranged from 0.1 to 1 lm 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
Summary
Porous Ni materials, such as plaques [1] and foams [2], are widely used in industry for the fabrication of electrodes for rechargeable batteries. The smaller pore size decreases the distance for electrons to travel from the current collector into the active material during cell discharge and improves the discharge rate characteristics for high power applications [3]. A complicating factor in the application of MnO2 in ES is low electronic conductivity of this material This problem can be addressed by the use of advanced current collectors, such as Ni plaques. The results presented below indicated that relatively high SC can be achieved at high active material loading using Ni plaques as current collectors In this approach, the high surface area and porous structure of the Ni plaques provided improved electrical contact of the current collector with active material and enabled good electrolyte access to the active material. We presented experimental results on the fabrication of composite electrodes, investigation into electrode microstructure and electrochemical behavior
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