All-solid-state lithium batteries are promising in terms of safety as well as high energy density compared to the conventional organic liquid-based lithium batteries. Despite the advances in achieving sufficiently high ionic conductivity for solid electrolytes, they suffer greatly from the interfacial stability which is detrimental to Li-ion transport leading to poor cycling performance. Poor physical contact, structural and chemical inhomogeneity as well as formation of undesired secondary phases at the interfaces contribute largely to the interfacial instability in all-solid-state lithium batteries. The secondary interphases can form during processing (especially high temperature co-sintering) as well as during cycling and therefore a careful investigation into the dynamics at electrolyte-cathode interfaces is critical to understand the formation of such interphases.<br/>The present work focusses on combining high temperature <i>ab initio</i> molecular dynamics (AIMD) simulations with global optimization methods to study the structural and chemical evolutions of interphases at the electrolyte-cathode interfaces. High-resolution microscopy and spectroscopy studies would complement the first principles simulations methods to unravel the interphases formed under different processing as well as cycling conditions. Lastly, we will evaluate the implications on the Li-ion transport across the interfaces. The present work focuses on garnet solid electrolytes (LLZO) interfacing with layered lithium cobalt oxide (LCO) cathodes. The developed first principles approach could be easily extended to other electrolyte-electrode interfaces for all-solid-state lithium batteries.

Understanding the dynamics of electrolyte-cathode interfaces in all-solid-state lithium batteries

ACS Spring 2022

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