High Li-ion conductivity in tetragonal LGPO: a comparative first-principles study against known LISICON and LGPS phases
Creators
- 1. Theory and Simulations of Materials (THEOS), École Polytechnique Fedérale de Lausanne, 1015 Lausanne, Switzerland
- 2. National Centre for Computational Design and Discovery of Novel Materials (MARVEL), 1015 Lausanne, Switzerland
- 3. IBM RSM Zurich Research Laboratory, Zurich, Switzerland
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Description
This work presents extensive first-principles (Car-Parrinello) molecular dynamics simulations of the solid-state electrolyte Li10GeP2O12 (LGPO) in a tetragonal phase -not synthesized so far- that is isostructural to the highly Li-ion conductive tetragonal phase of the sulfide analogue Li10GeP2S12 (LGPS). We provide comparative simulations of the experimentally known orthorhombic phase of LGPO (that we call here LISICON, from the family of superionic conductors to which LGPO belongs) and of the two experimentally known phases of LGPS, quasi-orthorhombic (called thio-LISICON) and tetragonal. We extract diffusion coefficients from fixed-cell simulations in the canonical ensemble and we study dynamical stability from variable-cell simulations in the isobaric-isothermal ensemble. The main outcome of this work is that, according to these simulations, although tetragonal LGPO is less stable than its orthorhombic allotrope, it exhibits a much higher conductivity, comparable to that presently estimated for both phases of LGPS. These results indicate that hypothetical tetragonal LGPO, if synthesized, could make a very attractive Li-ion conductor.
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References
Journal reference (Paper in which the data are presented and discussed) G. Materzanini, L. Kahle, A. Marcolongo, N. Marzari, Phys. Rev. Mater. (under revision after resubmission)
Preprint (Open access reference (to be modified once the paper is accepted, as a general reformulation of the structure of the paper has been done)) G. Materzanini, L. Kahle, A. Marcolongo, N. Marzari, arXiv:2010.08068 (2020)