Promoting favorable interfacial properties in lithium-based batteries using chlorine-rich sulfide inorganic solid-state electrolytes

The interfacial stability of lithium metal is a crucial aspect for all-solid-state battery development. Here, authors report argyrodite solid electrolytes containing LiCl framework, where the Cl ions construct a LiCl-rich interphase capable of improving battery performances. The use of inorganic solid-state electrolytes is considered a viable strategy for developing high-energy Li-based metal batteries. However, suppression of parasitic interfacial reactions and growth of unfavorable Li metal depositions upon cycling are challenging aspects and not yet fully addressed. Here, to better understand these phenomena, we investigate various sulfide inorganic solid electrolytes (SEs), i.e., Li7-xPS6-xClx (x = 0.6, 1.0, 1.3, 1.45, and 1.6), via ex situ and in situ physicochemical and electrochemical measurements. We found that the Cl distribution and the cooling process applied during the SE synthesis strongly influence the evolution of the Li|SE interface in terms of microstructure, interphase composition, and morphology. Indeed, for a SE with a moderate chlorine content (i.e., x = 1.3) and obtained via a slow cooling process after sintering, the Cl atoms are located on the surface of the SE grains as interconnected LiCl nanoparticles that form an extended LiCl-based framework. This peculiar microstructure facilitates the migration of the Cl ions to the Li|SE interface during electrochemical cycling, thus, favouring the formation of a LiCl-rich interphase layer capable of improving the battery cycling performances.

Automated summary

The interfacial stability of lithium metal is crucial for the development of all-solid-state batteries. In this study, researchers investigate the influence of chloride distribution and cooling process on the evolution of the Li|SE interface microstructure. They found that controlling these factors can lead to the formation of a LiCl-rich interphase layer, which improves battery cycling performance.