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chemrxiv-lgps.pdf (2.4 MB)
Defect Chemistry of Disordered Solid-State Electrolyte Li10GeP2S12
Preprints are manuscripts made publicly available before they have been submitted for formal peer review and publication. They might contain new research findings or data. Preprints can be a draft or final version of an author's research but must not have been accepted for publication at the time of submission.
submitted on 05.10.2019 and posted on 08.10.2019by Prashun Gorai, Hai Long, Eric Jones, Shriram Santhanagopalan, Vladan Stevanovic
Several classes of materials, including thiophosphates, garnets, argyrodites, and anti-perovskites, have been considered as electrolytes for all-solid-state batteries. Native point defects and dopants play a critical role in impeding or facilitating fast ion conduction in these solid electrolytes. Despite its significance, comprehensive studies of the native defect chemistry of well-known solid electrolytes is currently lacking, in part due their compositional and structural complexity. Most of these solid-state electrolytes exhibit significant structural disorder, which requires careful consideration when modeling the point defect energetics. In this work, we model the native defect chemistry of a disordered solid electrolyte, Li10GeP2S12 (LGPS), by uniquely combining ensemble statistics, accurate electronic structure, and modern first-principles defect calculations. We find that VLi, Lii, and PGe are the dominant defects. From these calculations, we determine the statistics of defect energetics; formation energies of the dominant defects vary over ~140 meV. Combined with ab initio molecular dynamics simulations, we find that anti-sites PGe promote Li ion conductivity, suggesting LGPS growth under P-rich/Ge-poor conditions will enhance ion conductivity. To this end, we offer practical experimental guides to enhance ion conductivity.