《Effect of Oxygen Doping Sources on Enhancing Air Stability and Lithium Metal Compatibility of Li5.5PS4.5Cl1.5 Electrolyte》

Oxygen (O) doping is a promising strategy for enhancing the air stability and lithium metal compatibility of sulfide solid electrolytes (SSEs). However, the impact of various O sources on the structure and properties of SSEs remains unclear. In this study, we synthesized a series of O-doped electrolytes, Li_5.5PS_4.5-xO_xCl_1.5 (LPSCO_x, 0.1 ≤ x ≤ 0.5), using Li₂O and P₂O₅ as O sources, and systematically investigated their differences in structure, air stability, and electrochemical properties. O preferentially substitutes sulfur (S) at the 16e site and begins to replace S at the 4d site once a certain O concentration is reached. Notably, the P₂O₅-doped electrolytes (P-LPSCO_x) exhibit a greater oxygen tolerance content (0.24) at the 16e site, along with better air stability, higher ionic conductivity, and superior lithium metal compatibility. XRD, SEM, and XPS analyses reveal that the P₂O₅-doped electrolytes exhibit larger cell parameters, higher densification, and fewer side reactions with lithium metal compared to the Li₂O-doped counterparts. This study provides valuable insights into the development of high-performance O-doped sulfide electrolytes.