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

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 La 2 O 3 with high chemical stability was selected as a doping component of Li 3 PS 4 sulfide electrolyte for the first time. The experimental results show that a certain amount of La 2 O 3 can not only increase the ionic conductivity of Li 3 PS 4 electrolyte, but also enhance their interfacial stability with the electrodes effectively. The XPS analytical results reveal the enhanced stability of Li 3 PS 4 electrolyte with La 2 O 3 doping due to the formation of SEI film on the lithium anode. Both the static and dynamic simulations illustrate that La 2 O 3 particles inside the Li 3 PS 4 electrolyte could facilitate the migration of Li + ion by way of the “space-charge effect.”