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 sintered or consolidated inorganic solid electrolyte 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 polymer is the same as or different than 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 10−8 S/cm to 5×10−2 S/cm at room temperature;
• wherein the inorganic solid electrolyte or the inorganic material particles in the first layer comprise an inorganic solid electrolyte material selected from a sulfide, hydride, halide, borate, phosphate, lithium phosphorus oxynitride (LiPON), or Garnet.