1.2 Volt manganese oxide symmetric supercapacitor (original) (raw)
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We report a very simple and fast route for a high capacitive birnessite type manganese dioxide (δ-MnO 2) synthesis, fully suitable to be applied as electrode in redox-based electrochemical supercapacitors. The material was obtained from a very efficient chemical reduction of potassium permanganate by nascent hydrogen in low temperature acid media. δ-MnO 2 was extensively characterized by several techniques confirming the obtainment through the proposed route. The supercapacitive properties of the novel structure were evaluated showing a specific capacitance of 190 F g −1 at 0.25 A.g −1. In addition, to the best of our knowledge, this is the first report regarding the chemical synthesis of δ-MnO 2 with no dependence of hazardous reducing agent, high temperature or high pressure commonly used to metal oxides production.
Applied Sciences
MnO2 is the most favorable material in power storage due to its technological significance and potential applications in pseudocapacitance (due to various oxidative states allowing efficient charge transfer to meet energy demands), where its properties are considerably influenced by its structure and surface morphology. In the present study, a facile hydrothermal route was used to produce different phases of MnO2 (α, β, and γ) with different morphologies. The electrochemical performance of the synthesized phases was studied in aqueous sodium sulfate as an electrolyte. X-ray diffraction, UV–Vis spectroscopy, and Fourier-transform infrared spectroscopy were used to characterize the synthesized material. The surface morphology and topography were examined using field-emission scanning electron microscopy. The direct band gap of α-, β-, and γ-MnO2 was found to be 1.86 eV, 1.08 eV, and 1.68 eV, lying in the semiconducting range, further enhancing the electrochemical performance. It was f...
Electrochemical characteristics of two-dimensional nano-structured MnO2 for symmetric supercapacitor
Electrochimica Acta, 2013
Manganese oxide (MnO 2 ) powders with various nano structures were prepared using MnSO 4 as a precursor through hydrothermal method. Manganese oxides with needles, rods and flakes structure were formed depending on oxidizer used. The flakes-shaped MnO 2 exhibited the higher capacitance values than other structures, both in aqueous and organic electrolytes. The charge storage mechanism observed in aqueous electrolyte is mixed type of charge insertion-extraction and surface adsorption mechanism while that in organic electrolyte is insertion-extraction. The higher specific capacitance of 342 F g −1 in NaOH, 429 F g −1 in LiClO 4 and 455 F g −1 in LiPF 6 was observed for the flakes-shaped MnO 2 electrode.
Journal of Physics: Conference Series
Herein, the simple electrolysis synthesis route to produce α-MnO2 is reported. The phase and crystal structure were evaluated by means of X-ray diffraction data collection and analysis. The morphological microstructure of as-prepared samples were captured by scanning electron microscope. The diameter distribution was studied by particle size analyzer. The electrochemical performance was systematically investigated by means of cyclic voltametry test. The produced MnO2 was also prepared to form composite with carbon. The results revealed that the MnO2/C composites perform outstanding characteristics mainly in terms of their maximum specific capacitance of 922.67 mF/g, with maximum power density of 90.150 W/kg, and maximum energy density of 0.063 Wh/kg. Therefore, the MnO2/C composite meets the criteria of the prospective applicability for supercapacitor.
Orange by-products e.g. orange peel and the extract of orange juice are used as sources for biological anti-oxidants such as ascorbic acid, flavonoids, phenolic compounds and pectins. In this study these antioxidants were successfully used to prepare nanosized materials of α-MnO 2 by cost effective and eco-friendly green chemistry method. The prepared oxides of MnO 2 which have unique properties as a storage cathode material were tested as a pseudocapacitor electrode materials in this study. X-ray powder diffraction (XRD) confirmed the structure of α-MnO 2 for the prepared samples. Thermal behavior of prepared oxides was tested using thermo-gravimetric analysis (TGA). Transmission electron microscopy (TEM) showed the nanosized nature of the prepared oxides. N 2-adsorption-desorption isotherms and pore-size distributions of prepared oxides showed that the surface areas are 5.63 and 8.40 m 2. g −1 for sample prepared from the extract of orange juice (OJ-MnO 2) and that prepared from the extract of orange peel (OP-MnO 2), respectively. Better electrochemical properties are obtained for OP-MnO 2 , the capacitance of OP-MnO 2 (139 F/g) is more than two times and half that obtained for OJ-MnO 2 (50 F/g) at the current density 0.5 A/g.
Journal of Power Sources, 2009
The electrochemical cyclability mechanism of nanocrystalline MnO 2 electrodes with rock salt-type and hexagonal-type structures was investigated to determine the relationship between physicochemical feature evolution and the corresponding electrochemical behaviour of MnO 2 electrodes. Rock salt MnO 2 and hexagonal-MnO 2 electrodes, with fibrous and porous morphologies, evolve into the antifluorite-type MnO 2 with a petal-shaped nanosheet structure after electrochemical cycling, similar to that observed in nanocrystalline antifluorite-type MnO 2 electrodes after electrochemical cycling. However, a different impedance response was observed for the rock salt MnO 2 and hexagonal-MnO 2 electrodes during the charge-discharge cycles, compared with the improved impedance response observed for the cycled antifluorite-type MnO 2. A dissolution-redeposition mechanism is proposed to account for the impedance response of the MnO 2 electrodes with different morphologies and crystal structures.
Cathodic Electrodeposition of Manganese Oxides for Electrochemical Supercapacitors
ECS Transactions, 2019
Manganese oxide films for electrochemical supercapacitors (ES) have been prepared by cathodic electrolytic and electrophoretic deposition. The cathodic reduction of KMnO4 solutions resulted in the formation of manganese oxide deposits. In another approach electrophoretic deposition (EPD) has been utilized for the deposition of manganese oxide nanoparticles prepared by a chemical precipitation method. The films exhibited pseudocapacitive behavior in a potential window of 0-1 V versus SCE in aqueous 0.5 M Na2SO4 and 0.5 M K2SO4 solutions. The deposition methods allowed the formation of porous films which exhibited a specific capacitance (SC) in the range of up to 240 F/g. The SC decreased with increasing scan rate. The films prepared by electrolytic deposition showed higher SC compared to the SC of EPD deposits.
MnO 2 nanoparticles for high-performance and semi-transparent supercapacitor electrode
2014
a Universidad de Málaga. Andalucía Tech. Departamentos de Física Aplicada & Ingeniería Química. Laboratorio de Materiales y Superficies (Unidad Asociada al CSIC), E29071 Málaga, Spain. b Instituto de Física, Facultad de Ingeniería, Herrera y Reissig 565, C.C. 30, 11000 Montevideo, Uruguay. c Instituto de Química, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso, Chile