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Structural evolution and stability of Sc2(WO4)3 after discharge in a sodium-based electrochemical cell

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Abstract

Sc2(WO4)3, prepared by solid state synthesis and constructed as an electrode, is discharged to different states in half-cell batteries, versus a Na negative electrode. The structural evolution of the Na-containing electrodes is studied with synchrotron powder X-ray diffraction (PXRD) revealing an increase in microstrain and a gradual amorphization taking place with increasing Na content in the electrode. This indicates that a conversion reaction takes place in the electrochemical cell. X-ray absorption spectroscopy (XAS) at the tungsten L3 absorption edge shows a reduction in the tungsten oxidation state. Variable temperature (VT) PXRD shows that the Sc2(WO4)3 electrode remains relatively stable at higher temperatures, while the Na-containing samples undergo a number of phase transitions and/or turn amorphous above ∼400 °C. Although, Sc2(WO4)3 is a negative thermal expansion (NTE) material only a subtle change of the thermal expansion is found below 400 °C for the Na-containing electrodes. This work shows the complexity in employing an electrochemical cell to produce Na-containing Sc2(WO4)3 and the subsequent phase transitions.

Graphical abstract: Structural evolution and stability of Sc2(WO4)3 after discharge in a sodium-based electrochemical cell

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Publication details

The article was received on 20 Nov 2017, accepted on 13 Dec 2017 and first published on 13 Dec 2017


Article type: Paper
DOI: 10.1039/C7DT04374K
Citation: Dalton Trans., 2018, Advance Article
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    Structural evolution and stability of Sc2(WO4)3 after discharge in a sodium-based electrochemical cell

    H. L. Andersen, O. K. Al Bahri, S. Tsarev, B. Johannessen, B. Schulz, J. Liu, H. E. A. Brand, M. Christensen and N. Sharma, Dalton Trans., 2018, Advance Article , DOI: 10.1039/C7DT04374K

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