Institute of Solid State Physics


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Fast Li Ion Transport in the Li7P3S11 Glass Ceramic as Seen by 6,7Li
D. Wohlmuth
Christian Doppler Laboratory for Lithium Batteries, Institute of Chemistry and Technology of Materials, Graz University of Technology
15:00 - 17:00 Monday 28 September 2015 Foyer Alte Technik

The glass ceramic Li7P3S11 (LPS), intensively studied by Tatsumisago [1], is a wellknown fast ion conductor [2]. Hence, it is undoubtedly a promising ceramic to be used in bulk-type all-solid-state batteries. The complex Li dynamics in LPS is, however, far from being understood completely.
To shed light on this issue, we performed temperature-variable 7Li (and 6Li) NMR measurements on a wide temperature range. Microscopic diffusion parameters were extracted from diffusion-induced rate peaks of an LPS sample that had been prepared by ball-milling with subsequent annealing. At 334 K the mean residence time between two successful Li jumps is in the order of 1 ns, cf. also Ref. [3]; In contrast to conductivity measurements, NMR reveals a range of activation energies with values ranging from 0.17 eV to 0.26 eV characterizing Li diffusivity in the bulk.
Surprisingly, the high-T flank of the rate peak, detectable above 350 K, is characterized by an even smaller slope. Its origin is yet unclear; most likely, it is connected to the presence of a large distribution of jump processes.

[1] M. Tatsumisago, M. Nagao, A. Hayashi, J. Asian Ceram. Soc., 1 (2013) 17
[2] Y. Seino, T. Ota, K. Takada, A. Hayashi, M. Tatsumisago, Energy Environ. Sci, 7 (2014) 627
[3] K. Hayamizu, and Y. Aihara, Solid State Ion., 238 (2013) 7