Mechanistic Insight into La2O3 Dopants with High Chemical Stability on Li3PS4 Sulfide Electrolyte for Lithium Metal Batteries

Abstract

Unlike the unstable liquid-state organic electrolyte at high temperatures, the solid-state electrolytes with high safety have attracted a broad prospect for the development of all-solid-state lithium metal battery (ASSLMB). Among the solid electrolytes, the sulfide-based electrolyte with low grain boundary resistances is one of the most practical choices due to its high lithium-ionic conductivity. The introduction of non-conducting oxide fillers into sulfide matrix is an effective way to increase their ionic conductivities and interfacial stabilities with the electrodes of battery simultaneously. Unfortunately, the acting mechanism of non-conducting oxide dopants with high chemical stability on the sulfide electrolyte has not been elucidated clearly. In this work, the rare-earth oxide La2O3 with high chemical stability was selected as a doping component of Li3PS4 sulfide electrolyte for the first time. The experimental results show that a certain amount of La2O3 can not only increase the ionic conductivity of Li3PS4 electrolyte, but also enhance their interfacial stability with the electrodes effectively. The XPS analytical results reveal the enhanced stability of Li3PS4 electrolyte with La2O3 doping due to the formation of SEI film on the lithium anode. Both the static and dynamic simulations illustrate that La2O3 particles inside the Li3PS4 electrolyte could facilitate the migration of Li+ ion by way of the “space-charge effect.”