Enhanced lithium dendrite suppression ability through SiO2 substitution in superionic halogen-rich argyrodites and their application in all-solid-state lithium batteries

Among the inorganic solid electrolytes, it has been reported that argyrodites of sulfide-based electrolyte systems have a number of advantages, including high ionic conductivity and mechanical flexibility. Despite these advantages, their poor compatibility with Li metal still represents a problem. In this work, we prepared a halogen-rich argyrodites Li6-xPS5-xCl1+x solid electrolyte using a high-energy ball milling process. According to the composition test, Li5.3PS4.3Cl1.7 exhibited a high ionic conductivity (9.0 mS cm-1) at room temperature. Thus, we proposed SiO2 doped halogen-rich argyrodites while aiming to achieve improved electrochemical performance and the ionic conductivity. At a value of 9.4 mS cm-1, the ionic conductivity of Li5.34P0.96Si0.04S4.22O0.08Cl1.7 compositions was slightly increased compared to that of Li5.3PS4.3Cl1.7 (9.0 mS cm-1). Moreover, that composition showed a higher critical current density (1.0 mA cm-2) than that of Li5.3PS4.3Cl1.7 (0.35 mA cm-2), indicating that SiO2 doped Li5.3PS4.3Cl1.7 solid electrolyte improved the compatibility of the electrolyte against Li metal by reducing the side reaction with the Li metals. The air stability was also enhanced after SiO2 doping. These results confirmed that metal oxide doping in halogen-rich argyrodites contributed to high ionic conductivity and good electrochemical performance.