English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

International audienceTemperature 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

Effect of Temperature on Structure and Electronic Properties of Nanometric Spinel-Type Cobalt Oxides