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.