Effect of temperature on structure and electronic properties of nanometric spinel-type cobalt oxides - Archive ouverte HAL
Article Dans Une Revue Journal of Physical Chemistry C Année : 2013

Effect of temperature on structure and electronic properties of nanometric spinel-type cobalt oxides

Résumé

Temperature is shown to have a huge influence on the electronic properties of nanometric spinel-type cobalt oxides precipitated at low temperature in alkaline media. The initial phase, with formula HxLiyCo3−δO4, contains hydrogen, lithium, cobalt vacancies, and a mixed valence Co4+/Co3+ within the structure, leading to an electronic conductivity higher than that of stoichiometric Co3O4. Its structural evolution under thermal treatment was studied by X-ray diffraction and chemical analysis, which reveal modifications in structure and compositions, involving water release, increase of the Co/O atomic ratio, and modification of the Co4+/Co3+ ratio. The RT to 300 °C range is particularly interesting as a single-phase domain and the materials obtained in this temperature range were investigated by chemical analysis, electronic conductivity and specific surface area measurements. Upon increasing temperature, the enhancement of the Co4+/Co3+ ratio, together with cationic redistribution in the spinel framework, results in an improvement of the electronic conductivity (more than 2 orders of magnitude for materials heated above 150 °C). Finally, the systematic thermal study of electronic conductivity and specific surface area of the materials allows to determine an optimal heat-treatment temperature leading to an optimized active electrode material for electrochemical energy storage applications, especially in supercapacitors. Such a solid state chemistry approach combining many material characterization techniques to reach a complete knowledge of the material is quite rare in the literature concerning oxides for supercapacitors.

Domaines

Matériaux
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Dates et versions

hal-00828061 , version 1 (22-07-2022)

Identifiants

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Gérôme Godillot, Liliane Guerlou-Demourgues, Laurence Croguennec, K. M. Shaju, Claude Delmas. Effect of temperature on structure and electronic properties of nanometric spinel-type cobalt oxides. Journal of Physical Chemistry C, 2013, 117 (18), pp.9065-9075. ⟨10.1021/jp3100359⟩. ⟨hal-00828061⟩
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