Abstract
Nanocomposites composed of MnO 2 and graphitic disordered mesoporous carbon (C MnO2/C) were synthesized for high total specific capacitance and redox pseudocapacitance (C MnO 2) at high scan rates up to 200 mV s -1. High resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray spectroscopy (EDX) demonstrated that MnO 2 nanodomains were highly dispersed throughout the mesoporous carbon structure. According to HRTEM and X-ray diffraction (XRD), the MnO 2 domains are shown to be primarily amorphous and less than 5 nm in size. For these composites in aqueous 1 M Na 2SO 4 electrolyte, C MnO2 reached 500 F/g MnO2 at 2 mV s -1 for 8.8 wt% MnO 2. A capacitance fade of only 20% over a 100-fold change in scan rate was observed for a high loading of 35 wt% MnO 2 with a C MnO2 of 310 F/g MnO2 at the highest scan rate of 200 mV s -1. The high electronic conductivity of the graphitic 3D disordered mesoporous carbon support in conjunction with the thin MnO 2 nanodomains facilitate rapid electron and ion transport offering the potential of improved high power density energy storage pseudocapacitors.
Original language | English |
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Pages (from-to) | 3160-3169 |
Number of pages | 10 |
Journal | Journal of Materials Chemistry |
Volume | 22 |
Issue number | 7 |
DOIs | |
State | Published - Feb 21 2012 |