| abstract |
A thermally-stable composite separator for an electrochemical cell that cycles lithium ions is provided, along with methods of making the composite separator. The method includes contacting one or more surface regions of a coated substrate with a coagulant. The coated substrate includes an insulating porous substrate and at least one non-porous polymeric layer including a polymer, one or more nanoparticles, one or more sub-micron particles, and a solvent. Contacting the coated substrate with the coagulant medium removes the solvent causing the polymer to precipitate forming at least one substantially uniform porous polymer layer in place of the at least one non-porous polymeric layer. The coagulant medium has a viscosity greater than that of the solvent and a solubility parameter distance between the polymer and the coagulant medium is less than that between the polymer and water. |