Facile Synthesis of Li₇P₂S₈I for All-Solid-State Lithium Batteries

Sulfide electrolyte Li7P2S8I has received extensive attention on account of its high ionic conductivity and remarkable stability. However, a long processing time and sophisticated synthesis procedures are generally required. In this study, Li7P2S8I is synthesized through the combination of melt-quenching and high-energy ball milling, significantly reducing ball milling time compared with the conventional mechanical milling method. The generation of highly conductive thio-LISICON II phase facilitates the fast Li+ transportation. The optimized Li7P2S8I exhibits a favorable powder cold-pressed ionic conductivity of 1.51 mS cm–1 and a relatively high critical current density of 0.55 mA cm–2. The resultant LiCoO2/Li7P2S8I-700/Li all-solid-state battery delivers an initial reversible capacity of 119.1 mAh g–1 with a capacity retention of 91.5% after 20 cycles under 0.1 C. This study introduces an efficient approach for the rapid synthesis of Li7P2S8I for all-solid-state lithium batteries.