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MM: Fachverband Metall- und Materialphysik
MM 5: Materials in Energy Conversion: Mechanical Properties and Solid State Batteries
MM 5.8: Talk
Monday, March 27, 2023, 12:15–12:30, SCH A 215
Dynamic stability and ab initio free energy calculations of argyrodite Li6PS5Cl solid electrolyte — •Yongliang Ou, Yuji Ikeda, Prashanth Srinivasan, and Blazej Grabowski — Institute for Materials Science, University of Stuttgart, 70569 Stuttgart, Germany
High ionic conductivity of argyrodite Li6PS5Cl, which was shown in both experiments and simulations, renders it a promising candidate for the solid electrolyte in all-solid-state lithium-ion batteries. Although the diffusion mechanism has been intensively investigated in previous studies, the dynamic and thermodynamic stability of Li6PS5Cl have not yet been fully understood. To address this issue, systematic investigations are carried out under the ab initio framework in this study. At 0 K, the dynamic instability of the ideal structure is revealed by the calculated imaginary phonon modes. Molecular dynamics simulations accelerated by machine-learning interatomic potentials show dynamic stabilization via vibrational entropy at finite temperatures. Further, ab initio free energy calculations are performed in wide temperature and pressure ranges utilizing a multistage thermodynamic integration technique. The calculated free energies provide important information for subsequent studies focusing on the energetic aspects, e.g., defect or grain boundary formation energy, of Li6PS5Cl. It can be expected that the present results benefit the research and application of all-solid-state lithium-ion batteries.