Fabrication of ultrathin solid electrolyte membranes of β-Li3PS4 nanoflakes by evaporation-induced self-assembly for all-solid-state batteries

Abstract

All-solid-state lithium batteries are attractive candidates for next-generation energy storage devices because of their anticipated high energy density and intrinsic safety. Owing to their excellent ionic conductivity and stability with metallic lithium anodes, nanostructured lithium thiophosphate solid electrolytes such as β-Li₃PS₄ have found use in the fabrication of all-solid lithium batteries for large-scale energy storage systems. However, current methods for preparing air-sensitive solid electrolyte membranes of lithium thiophosphates can only generate thick membranes that compromise the battery's gravimetric/volumetric energy density and thus its rate performance. To overcome this limitation, the solid electrolyte's thickness needs to be effectively decreased to achieve ideal energy density and enhanced rate performance. Herein, we show that the evaporation-induced self-assembly (EISA) technique produces ultrathin membranes of a lithium thiophosphate solid electrolyte with controllable thicknesses between 8 and 50 μm while maintaining the high ionic conductivity of β-Li₃PS₄ and stability with metallic lithium anodes up to 5 V. It is clearly demonstrated that this facile EISA approach allows for the preparation of ultrathin lithium thiophosphate solid electrolyte membranes for all-solid-state batteries.