Multi-Layer Solid Electrolyte Separator for a Lithium Secondary Battery and Manufacturing Method

A flame-resistant composite separator for use in a lithium battery, wherein the composite separator comprises at least a first layer and a second layer laminated together, wherein: (A) the first layer comprises a layer of inorganic solid electrolyte (e.g., a sintered solid structure) or a layer of polymer composite comprising 60%-99% by volume of inorganic material particles, inorganic material fibers, and/or polymer fibers dispersed in or bonded by a first polymer; and (B) the second layer comprises a second polymer and from 0.1% to 50% by weight of a lithium salt dispersed in the second polymer; wherein the first layer and the second layer each has a thickness from 20 nm to 100 μm and a lithium-ion conductivity from 10S/cm to 5×10S/cm at room temperature.