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Exfoliation and restacking of manganese and cobalt based lamellar oxides for supercapacitor electrodes

Abstract : The ever increasing demand of renewable energies imposes, due to theirintermittent nature, the development of performant energy storage devices. Supercapacitorsare reliable devices that offer a high power density and numerous investigations are focusingon increasing their energy densities. In particular, asymmetric "metal oxides / activatedcarbons" supercapacitors are possible candidates. The MnO2/carbon system is the mostinvestigated system, due to its capability to work in aqueous medium at potentials up to 2 V,as well as to the low cost and environmental friendliness of manganese. Nevertheless, thissystem suffers from the poor electronic conductivity of manganese. This work reports anoriginal strategy for novel electrode materials involving exfoliation and restacking processesof lamellar “building blocks”: lamellar manganese oxides for their pseudocapacitiveproperties and lamellar cobalt oxyhydroxides for their high electronic conductivity. Thematerial engineering strategy focuses on the exfoliation of the lamellar materials intooligolamellae. The obtained suspensions are then restacked through various strategies andnew well defined mixed oxides are obtained. After structural and morphologicalcharacterization, it is clear that these nanocomposites present an intimate mix of the twoinitial phases. The electrochemical responses are hereby enhanced, proving the intertwinedrelationship between structure, morphology and properties. Furthermore, this architecturalapproach of building novel electrode materials is original and efficient and can easily betransposed to other “building blocks”, including graphene.
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Celine Tang. Exfoliation and restacking of manganese and cobalt based lamellar oxides for supercapacitor electrodes. Material chemistry. Université de Bordeaux, 2017. English. ⟨NNT : 2017BORD0789⟩. ⟨tel-01696266⟩

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