Abstract
A hierarchical strategy has been adopted for the development of ternary composites, where nanostructured δ-MnO2 has been fabricated sonochemically on a unique mesoporous binary composite made of 3,4-ethylenedioxythiophene (EDOT) and reduced graphene oxide (rGO) in order to achieve maximum loading of 89% Mn+4 oxidation state essential for high capacitance value. All composite samples have been characterized by transmission electron microscopy, x-ray diffraction, Fourier infrared spectroscopy and thermogravimetry analysis. Oxidation states of manganese have been evaluated by x-ray photoelectron spectroscopy (XPS). The charge storage mechanism in the nanocomposite materials is primarily governed by the unique mesoporous structure developed during oxidative polymerization of the EDOT and rGO in the composites. The cumulative charge accumulation reveals the storage mechanism where, the entrance of Li+ ion into the mesoporous layered structure of rGO based nanocomposites during reduction followed by re-entrance of Li+ ion on oxidation, is comparable to that of Li+ ion adsorption/desorption on the surface of the nanocomposites. Impedance measurements are carried out to evaluate the contribution of the pseudocapacitance over the electrical double layer capacitance. Achievement of high specific capacitance (345 F g−1) with small attenuation (∼ 12%) over 1000 continuous charging/discharging cycles, suggests that the ternary nanocomposites with 70% loading of δ-MnO2 (RGPT70M) acts as a promising candidate for the electrode materials of the supercapacitor.
Published Version
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