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MM: Fachverband Metall- und Materialphysik

MM 31: Transport in Materials: Diffusion, Charge, or Heat Conduction II

MM 31.10: Vortrag

Donnerstag, 12. März 2026, 12:45–13:00, SCH/A216

Stoichiometric Locking in the High State of Charge in Solid Ion Conductors: A Kinetic Monte Carlo Study — •Roya Ebrahimi Viand, Chiara Panosetti, Christoph Scheurer, Karsten Reuter, and Sebastian Matera — Fritz-Haber-Institut der MPG, Berlin

The advancement of solid-state batteries critically relies on a deep understanding of ion transport in crystalline electrolytes and electrode active materials. We present a kinetic Monte Carlo (kMC) approach with fast update rules for transition propensities that enables efficient simulation of systems with long-range Coulomb interactions. Our study systematically probes the effects of state of charge (SOC), temperature, and applied external electric field on ionic mobility. We observe a pronounced mobility minimum near 100% SOC, where ions freeze in a low-energy Coulomb superlattice configuration that persists even under applied electric fields. Deviations from stoichiometry dramatically enhance transport by introducing defect pathways, with nearly symmetric behavior for ion and vacancy diffusion. By decomposing the state of charge into a reference and an excess carrier concentration (ΔSOC), we find that the intrinsic mobility per excess carrier remains approximately constant across different SOC values, revealing that transport is fundamentally mediated by the ΔSOC disrupting the reference structure. Analysis of effective activation energies across different SOC values reveals behavior consistent with percolation-controlled transport, where the availability of defect-mediated pathways strongly influences the energy landscape for ion diffusion.

Keywords: Kinetic Monte Carlo; Charge Transport; Percolation