In:
ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2016-03, No. 2 ( 2016-06-10), p. 707-707
Abstract:
We investigated the local structure and the dynamics of Li and Na ions in the solid electrolytes Li 1.2 Al 0.6 Ti 1.4 (PO 4 ) 3 , Li 1.6 Al 0.6 Ge 1.4 (PO 4 ) 3 , and Na 3.4 Sc 2 (SiO 4 ) 0.4 (PO 4 ) 2.6 by NMR spectroscopy. While 27 Al MAS NMR spectroscopy reveals the presence of only octahedral [AlO 6 ] environments for Li 1.6 Al 0.6 Ge 1.4 (PO 4 ) 3 , Li 1.2 Al 0.6 Ti 1.4 (PO 4 ) 3 exhibits large amounts of Al located in tetrahedral [AlO 4 ] environments. 31 P MAS NMR measurements reveal multiple environments with different Al/Ge next nearest neighbor composition around P and the relative intensities are in good agreement with a statistical arrangement of Ge/Al on the octahedral sites for Li 1.6 Al 0.6 Ge 1.4 (PO 4 ) 3 . For Li 1.2 Al 0.6 Ti 1.4 (PO 4 ) 3 , the 31 P MAS NMR results indicate the presence of structural disorder. These results are confirmed by X-ray diffraction and Rietveld refinements. The dynamics of Li ions have been investigated by temperature-dependent static 7 Li NMR lineshape analysis and 7 Li NMR relaxometry. Jump rates of about 7∙10 8 s -1 can be estimated for Li 1.6 Al 0.6 Ge 1.4 (PO 4 ) 3 at 400 K and the activation barrier for a single Li ion jump is 0.14 eV. A Li diffusion coefficient of 10 -11 m 2 /s and a Li ion conductivity of 3.6 mS/cm can be estimated at 400 K. For Na 3.4 Sc 2 (SiO 4 ) 0.4 (PO 4 ) 2.6 , NMR spectroscopy reveals that Si and P are arranged statistically on the tetrahedral sites and Sc is exclusively located on octahedral sites. Temperature-dependent 23 Na NMR measurements show a strong increase of the asymmetry of the local environment, consistent with XRD measurements which yield a strongly anisotropic thermal expansion. Jump rates of higher than 5∙10 3 s -1 can be estimated for the Na ions for temperatures above 300 K.
Type of Medium:
Online Resource
ISSN:
2151-2043
DOI:
10.1149/MA2016-03/2/707
Language:
Unknown
Publisher:
The Electrochemical Society
Publication Date:
2016
detail.hit.zdb_id:
2438749-6
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