title: Sparse Cyclic Excitations Explain the Low Ionic Conductivity of Stoichiometric Li_{7}La_{3}Zr_{2}O_{12}.
abstract: We have performed long time scale molecular dynamics simulations of the cubic and tetragonal phases of the solid lithium-ion electrolyte Li_{7}La_{3}Zr_{2}O_{12} (LLZO), using a first-principles parametrized interatomic potential. Collective lithium transport was analyzed by identifying dynamical excitations: persistent ion displacements over distances comparable to the separation between lithium sites, and stringlike clusters of ions that undergo cooperative motion. We find that dynamical excitations in c-LLZO (cubic) are frequent, with participating lithium numbers following an exponential distribution, mirroring the dynamics of fragile glasses. In contrast, excitations in t-LLZO (tetragonal) are both temporally and spatially sparse, consisting preferentially of highly concerted lithium motion around closed loops. This qualitative difference is explained as a consequence of lithium ordering in t-LLZO and provides a mechanistic basis for the much lower ionic conductivity of t-LLZO compared to c-LLZO.
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8234, PHENIX, F-75005 Paris, France.|CNRS, Université de Bordeaux, ICMCB, 87 avenue du Dr. A. Schweitzer, 33608 Pessac Cedex, France.|Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, France.
authors.forename: Mario
authors.initials: M
authors.lastname: Burbano
authors.affiliation: CNRS, Université de Bordeaux, ICMCB, 87 avenue du Dr. A. Schweitzer, 33608 Pessac Cedex, France.|Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, France.
authors.forename: Dany
authors.initials: D
authors.lastname: Carlier
authors.affiliation: Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes cedex 3, France.
authors.forename: Florent
authors.initials: F
authors.lastname: Boucher
authors.affiliation: Department of Chemistry, University of Bath, Claverton Down BA2 7AY, United Kingdom.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Morgan
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8234, PHENIX, F-75005 Paris, France.|Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, France.|Maison de la Simulation, USR 3441, CEA-CNRS-INRIA-Université Paris-Sud-Université de Versailles, F-91191 Gif-sur-Yvette, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Salanne