One Stone, Three Birds: An Air and Interface Stable Argyrodite Solid Electrolyte with Multifunctional Nanoshells

Li₆PS₅Cl (LPSC) solid electrolytes, based on Argyrodite, have shown potential for developing high energy density and safe all-solid-state lithium metal batteries. However, challenges such as interfacial reactions, uneven Li deposition, and air instability remain unresolved. To address these issues, a simple and effective approach is proposed to design and prepare a solid electrolyte with unique structural features: Li₆PS₄Cl_0.75-OF_0.25 (LPSC-OF_0.25) with protective LiF@Li₂O nanoshells and F and O-rich internal units. The LPSC-OF_0.25 electrolyte exhibits high ionic conductivity and the capability of “killing three birds with one stone” by improving the moist air tolerance, as well as the interface compatibility between the anode or cathode and the solid electrolyte. The improved performance is attributed to the peculiar morphology and the self-generating and self-healing interface coupling capability. When coupled with bare LiCoO₂, the LPSC-OF_0.25 electrolyte enables stable operation under high cutoff voltage (≈4.65 V vs Li/Li⁺), thick cathodes (25 mg cm⁻²), and large current density (800 cycles at 2 mA cm⁻²). This rationally designed solid electrolyte offers promising prospects for solid-state batteries with high energy and power density for future long-range electric vehicles and aircrafts.