Low-Cost High-Air-Stability Argyrodite Electrolyte Delivering Excellent Interface Compatibility in All-Solid-State Lithium Metal Batteries

Abstract

Argyrodite Li₆PS₅Cl (LPSC) solid electrolytes have shown great promise for all-solid-state lithium batteries owing to their high ionic conductivity and mechanical robustness, yet they face three critical challenges: high production costs, detrimental interfacial reactions with lithium anodes, and poor air stability. In this work, an oxygen and fluorine co-doped argyrodite electrolyte Li_5.5PS_2.5O₂Cl_1.4F_0.1 (LPSOCF) is developed. Strategic precursor selection lowers the material cost of LPSOCF to only 3.65% that of LPSC, facilitating kilogram-scale synthesis and marking a critical step towards commercialization. The incorporation of oxygen and fluorine stabilizes the PS₄^3- tetrahedral framework and decreases the water adsorption energy, endowing the electrolyte with markedly enhanced air stability (retaining 95.6% of its original ionic conductivity after 10h exposure to 10% humidity). Meanwhile, the synergistic doping of oxygen and fluorine induces the in-situ formation of a Li₂O/LiF/Li₃PO₄ multicomponent interface layer between the electrolyte and the lithium metal anode, conspicuously bolstering interface stability in the all-solid-state lithium metal batteries. Consequently, the Li|LPSOCF|Li symmetric batteries achieve a critical current density (CCD) of 4.5 mA cm^-2 and exhibit stable lithium plating/stripping over 2800 hours. Furthermore, the Li|LPSOCF-Li_2.5ZrCl_5.5O_0.5 |LiCoO₂ batteries retain 80% of their initial capacity after 635 cycles at 0.5C and 84% after 1000 cycles at 1C. This work constitutes a cornerstone for the scalable commercial deployment of argyrodite electrolytes in all-solid-state batteries.