Optimizing milling and sintering parameters for mild synthesis of highly conductive Li_5.5PS_4.5Cl_1.5 solid electrolyte

The Li_5.5PS_4.5Cl_1.5 electrolyte gains significant attention due to its ultrahigh ionic conductivity and cost-effectiveness in halogen-rich lithium argyrodite solid electrolytes. The conventional synthetic method for obtaining the electrolyte involves mechanical milling followed by post-annealing. However, these synthesis methods typically involve high milling speeds, elevated temperatures, and prolonged durations, resulting in both high energy consumption and potential damage to the electrolyte. In this study, we successfully obtained Li_5.5PS_4.5Cl_1.5 with a high conductivity of 7.92 mS cm^-1 using a milling speed of 400 rpm and annealing at 400 °C for 5 hours. When incorporated into a Li₄Ti₅O₁₂-based all-solid-state battery, this electrolyte demonstrates stable cycling performance across varying temperatures.