The effect of calcium impurities of β″-alumina on the degradation of NaxCoO2 cathodes in all solid state sodium-ion batteries

β″-alumina is a promising solid electrolyte candidate for room-temperature all-solid-state sodium-ion batteries due to its high sodium ionic conductivity of up to 10−2 S cm−1 at room temperature. However, calcium impurities are known to be present in the Al2O3 precursors used to produce commercial β...

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Veröffentlicht in:Solid state ionics 2019-11, Vol.341, p.115041, Article 115041
Hauptverfasser: Kehne, P., Guhl, C., Alff, L., Hausbrand, R., Komissinskiy, P.
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Sprache:eng
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Zusammenfassung:β″-alumina is a promising solid electrolyte candidate for room-temperature all-solid-state sodium-ion batteries due to its high sodium ionic conductivity of up to 10−2 S cm−1 at room temperature. However, calcium impurities are known to be present in the Al2O3 precursors used to produce commercial β″-alumina. Here we present a study on the impact of the calcium impurities which are diffusing in a temperature controlled process from the β″-alumina substrates into the NaxCoO2 layered oxide cathode. The increasing calcium content in the NaxCoO2 cathode leads to a degradation due to the formation of the calcium-rich Ca3Co4O9 phase. The electrochemical performance of sodium-ion batteries is investigated with NaxCoO2/β″-alumina/Na solid-state model batteries. The thin-film cathodes were grown onto commercial β″-alumina ceramic substrates by pulsed laser deposition and cycled between 2.0 and 3.8 V with metallic sodium anodes. •Temperature controlled calcium impurity diffusion from β″-alumina.•NaxCoO2 degradation into Ca3Co4O9•All-solid state NaxCoO2/β″-alumina/Na model battery
ISSN:0167-2738
1872-7689
DOI:10.1016/j.ssi.2019.115041