METHOD OF MANUFACTURING A THIN FILM COMPOSITE SOLID ELECTROLYTE

A method for manufacturing an improved thin film composite solid electrolyte is provided. The method includes spray coating an aqueous suspension of ceramic particles onto a substrate to form a ceramic thin film. The film is sintered to form a porous ceramic structure having an interconnected necked morphology that defines cavities. The cavities are backfilled with an polymer electrolyte, for example a crosslinkable poly(ethylene oxide) (PEO)-based polymer electrolyte. The resulting thin film composite solid electrolyte is highly ionically conductive and mechanically robust with good manufacturability, particularly suitable for, but not limited to lithium metal batteries. The present method represents a departure from conventional mixing-then-casting methods and instead includes the fabrication of a solid electrolyte having a high ceramic volume fraction, high ionic conductivity, low thickness, and good chemical stability with metallic lithium.