THEOS

Members

Leonid Kahle (EPFL)
Giuliana Materzanini (EPFL)
Aris Marcolongo (now at IBM)

Research:

Our focus is to understand the fundamental microscopic mechanisms driving ionic diffusion in solid-state structures, and use this knowledge to engineer materials for electrolyte applications. Solid-state electrolytes are safe and performing alternatives to current state-of-the-art liquid electrolytes in lithium-ion batteries. To achieve this goal we are working on:

• Accelerating first-principles molecular dynamics: An accurate, general, but computationally demanding approach to estimate ionic conductivities is a solid-state structures is the simulation of the time-evolution of the system via molecular dynamics in the framework of density functional theory. This is resource-limited to the study of few materials. For high-throughput screening applications, we have developed a new 'pinball' model that can be used in molecular dynamics. In this model, lithium or other diffusing cations are treated as core charges moving through a fixed charge density and host-lattice. Due to these approximations, we achieve computationally inexpensive that still retain the required accuracy [1]
• Automatized transport coefficients: For an estimate of transport coefficients from molecular dynamics trajectories, experience, supervision and advanced analysis tools are required. We aim at developing open-source tools, based on the AiiDA platform, to automatize this cumbersome procedure and converge transport coefficients to a user-defined accuracy with minimal intervention, while retaining full provenance of the results.
• First-princples studies of diffusion: The underlying mechanism can be studied and elucidated through the simulation of the system with first-principles molecular dynamics. Such study has shown interesting correlation effects in one of the best lithium-ionic conductors LiGePS [2] and was also used to understand the mechanism of proton diffusion in Y-doped BZO [3].

News

Publications

• [1] L. Kahle, A. Marcolongo, N. Marzari, Modeling lithium-ion solid-state electrolytes with a pinball model Phys. Rev. Materials 2, 065405 (2018), or ArXiv:1805.10263
• [2] A. Marcolongo, N. Marzari. Ionic correlations and failure of Nernst-Einstein relation in solid-state electrolytes, Phys. Rev. Materials 1, 025402 (2017)
• [3] A. Fluri, A. Marcolongo, V. Roddatis, A. Wokaun, D. Pergolesi, N. Marzari, and T. Lippert, Enhanced Proton Conductivity in Y-Doped BaZrO3 via Strain Engineering, Advanced Science 4, 1700467 (2017).

Images