NOVELTY - A porous separator consists of ceramic particles and a polymeric binder, and has porosity of 35-50% and average pore size of 10-50 nm.    USE - Porous separator is used for electrochemical cell and transferring heat through battery (all claimed) e.g. lithium-ion battery for electric vehicle, hybrid vehicle and portable computer. Can also be used for capacitor.    ADVANTAGE - The nanoporous separator has excellent thermal conductivity, dimensional stability, mechanical strength and ionic conductivity. The battery containing the porous separator is safe, and is manufactured using economical automated processing equipment by a simple method.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) electrochemical cell, which comprises an anode, a cathode, an inorganic electrolyte comprising a lithium salt, and a porous separator layer comprising an organic polymer and ceramic particles. The porous separator layer has porosity of 35-50% and average pore size of 10-90 nm, and exhibits less than 1% shrinkage when exposed at 200 degrees C for 1 hour or more;    (2) manufacture of flexible porous composite separator, which involves formulating a dispersion comprising an organic polymeric material, inorganic ceramic material, and a solvent, applying the dispersion to a substrate, forming a coating, drying and curing the coating, and removing the coating from the substrate. The flexible porous composite separator has porosity of 35-50% and average pore size of 10-50 nm and exhibits less than 1% shrinkage when exposed at 200 degrees C for 1 hour or more;    (3) method for transferring heat through battery, which involves increasing the temperature of a primary electrode in a lithium-ion battery, and transferring heat from the primary electrode through the porous separator to a secondary electrode; and    (4) flexible composite ceramic separator, which comprises a polymer, a primary inorganic particulate material dispersed uniformly in the polymer, and a secondary inorganic particulate material dispersed uniformly in the polymer. The secondary inorganic particulate material differs in particle size or composition from the primary inorganic particulate material. The flexible composite ceramic separator exhibits a thermal conductivity which is more than the thermal conductivity of a comparative composite ceramic separator of the same composition which differs only by including a single inorganic particulate material in an amount equal to total amount of primary and secondary inorganic particulate materials.