Two-step liquid-phase synthesis of argyrodite Li6PS5Cl solid electrolyte using nonionic surfactant

Abstract

In the present work, argyrodite Li₆PS₅Cl sulfide solid electrolyte is prepared by a liquid phase process, consisting of two steps: (1) suspension-reaction under the ultrasonication of Li₂S, P₂S₅, and LiCl precursors in acetonitrile and, (2) dissolution-precipitation involving the addition of ethanol/acetonitrile and solvents removal by heating at 180 °C. The effect of the addition of a nonionic surfactant on the properties of the sulfide solid electrolyte is also studied. The synthesis process allows to obtain Li₆PS₅Cl argyrodite solid electrolyte with high ionic conductivity of 2.0 × 10⁻⁴ S cm⁻¹, the low activation energy of 0.22 eV, and electrochemical stability up to 5 V (vs. Li). A regular particle distribution with a size smaller than 1 μm is obtained by the addition of the surfactant.