Electrochemical performance of MnOx·center dot nH(2)O@Ni composite foam electrodes for energy storage in KOH media
| Autor: | K.I. Siwek, S. Eugénio, Maria de Fátima Montemor, T.M. Silva |
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| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Supercapacitor
Dióxido de manganês Materials science Functional 020209 energy General Chemical Engineering Composite number Manganese dioxide 02 engineering and technology Thermal treatment Conductivity 021001 nanoscience & nanotechnology Electrochemistry Amorphous solid Chemical engineering Electrodeposition 3D nickel foam Electrode 0202 electrical engineering electronic engineering information engineering Supercapacitors 0210 nano-technology Porosity |
| Zdroj: | Repositório Científico de Acesso Aberto de Portugal Repositório Científico de Acesso Aberto de Portugal (RCAAP) instacron:RCAAP |
| Popis: | Nanostructured porous MnO2, especially its hydrated amorphous and low crystalline form (MnO2·nH2O), has been one of the most promising material considered for charge storage applications, due to electrochemical similarities with RuO2 and its relative low cost. However, the intrinsic poor conductivity of MnO2 combined with the presence of structural water, which provides high ionic but low electronic conductivity, is a great hindrance for wider application. An effective approach to overcome this drawback involves the deposition of thin MnO2 layers on porous, high surface area metallic scaffolds. The present work addresses this route and provides novel insights thanks to the combination of MnOx·nH2O with custom-made Ni foams, fabricated via one-step electrodeposition using the dynamic hydrogen bubble template (DHBT). The porous Ni foams provide a scaffold with a 3D architecture with optimized pore size and surface. The composite electrode was fabricated by anodic deposition of MnOx·nH2O on the 3D Ni foams. The electrochemical behaviour was tested in 1 M KOH, since there are very few studies addressing the electrochemical behaviour of MnOx·nH2O in alkaline media for electrochemical supercapacitors applications. In addition, thermal treatment (150–250 °C) was performed to evaluate the effect of hydration on the material properties. The results revealed that the as-obtained composites are highly stable, displaying much higher specific capacitances with 73–90% (depending on the mass load) capacitance retention compared to their de-hydrated counterparts. The charge-discharge processes were found to be highly reversible throughout 5000 cycles, maintaining almost 100% columbic efficiency. In conclusion, the MnOx·nH2O@Ni composite electrodes showed a very stable pseudocapacitive behaviour and exceptional cycling performance in 1 M KOH, being therefore a promising alternative charge storage electrode for electrochemical supercapacitors. |
| Databáze: | OpenAIRE |
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