Theoretical Understanding of the Deposition and Growth of Lithium in a Solid State Lithium-ion Conducting Electrolyte

All-solid-state lithium batteries have been extensively pursued for next-generation energy storage, in which the state-state electrolyte (SSE) is a key component. The deposition of metallic lithium inside an SSE has been observed and is a concerning issue for development of the forefront all-solid-state lithium batteries. Unlike lithium dendrites that form and grow from the surface of Li-metal anode, metallic lithium can nucleate and propagate directly inside the bulk SSE, which can cause an instant failure of SSE.<br/><br/>In this work, we first present a theoretical model that is built based on non-equilibrium thermodynamic theory while taking consideration of the electronic conduction in an SSE. The electronic conductivity is a key variable to determine the chemical potential of lithium. The distribution of chemical potential of lithium is then calculated based on transport properties of an SSE. When the lithium chemical potential is higher than the sum of the elastic energy and surface energy, the change of Gibbs free energy for lithium formation is less than zero, which is the thermodynamic criterion for the deposition of lithium in an SSE. We will present our ongoing experimental research, as well as the electrochemical and materials characterization, to elucidate the approaches to control the deposition of lithium in an all-solid-state battery.<br/><br/>Acknowledgement: We would like to thank the supports from NASA under 80NSSC21M0333 and NSF under NSF-2119688.