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Description
The Y-halides Li3YBr6 and Li3YCl6 were recently considered as potential electrolytes for all-solid-state batteries [1] as they exhibit sufficiently high ionic conductivities at room temperature. The aim of this study [2] is to elucidate the relationship between several parameters such as the morphology, defects and size effects on the Li ion hopping processes in Li3YBr6. Here, the ternary halide was prepared by both conventional solid-state synthesis and directly via mechanosynthesis under ambient conditions. Morphology and structure of nanocrystalline and annealed Li3YBr6 were studied by x-ray powder diffraction and 6Li, 79Br MAS NMR. Broadband impedance spectroscopy was employed to determine total conductivities over a wide temperature range. As an example, for annealed Li3YBr6 we obtained 1.52 mS/cm, the activation energy Ea was 0.28 eV. Time-domain 7Li NMR spin-lattice relaxation measurements were used to investigate ion transport also from the atomic-scale point of view. The elementary jump process is characterized by an activation energy as low as Ea = 0.15 eV; at 313 K the Li+ self-diffusion coefficient is in the order of 6e-12 m2 s-1. Changes seen in both broadband conductivity and 7Li NMR could be attributed to changes of the cation sublattices recently determined by neutron diffraction [3]. Most interestingly, the ion transport in nanocrystalline Li3YBr6, which we obtained after only 1 h of milling, is only slightly slower. Hence, a non-annealed sample (0.44 mS/cm) might indeed serve as an alternative and sustainable electrolyte for all-solid-state batteries.
[1] T. Asano et al., Adv. Mater. 2018, 30, 1803075.
[2] M. Gombotz and H. M. R. Wilkening, ACS Sust. Chem. Eng., 2021, 9, 2, 743-755
[3] R. Schlem et al., Chem. Mater., 2021, 33, 1, 327-337
| Speaker Country | Austria |
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