TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The inorganic particles include calcium carbonate, aluminum oxide, silicon dioxide, barium titanate or titanium dioxide having the diameter of 0.1-2 mu m. Preferred Composition: The mixed solution comprises solid content (heat resistant resin and inorganic particles) of 8-35 wt.% based on 100 wt.% of the overall solution.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The heat resistant resin to form the coated layer is polyphenylsulfone, polyarylamide or polyarylate. The coated layer has volume ratio of the heat resistant resin to the inorganic substance of 30/70-10/90 vol.%. The overall thickness of the coated layer is 10-60% of that of the microporous polyethylene film, and porosity of the coated layer itself is 15-60%. EXAMPLE - High density polyethylene (having weight average molecular weight of 3.8x 105) was mixed with a mixture (1:2 in weight ratio) of dibutyl phthalate and paraffin oil as diluent, where the contents of the polyethylene and diluent were 30 wt.% and 70 wt.%, respectively. The composition was extruded at 240 degrees C by using a biaxial compounder equipped with a T-die, and passed through a section set at 170 degrees C to induce phase separation of polyethylene from the diluent. Sheet was prepared by using a casting roll. A sheet prepared was elongated 6 times at 128 degrees C of elongation temperature in machine and transverse directions, respectively, by using a consecutive biaxial stretcher. After elongation, heat-setting temperature was 128 degrees C, and the heat-setting width was controlled in three stages. Final thickness of the prepared microporous polyethylene film (separator) was 16 mu m, gas permeability was 130 seconds and shrinkage at 130 degrees C was 20% and 25%, respectively, in machine and transverse directions. A solution of overall solid content of 25 wt.% was prepared by dissolving polyarylamide (having melting temperature of 231 degrees C, 30 vol.%) and barium titanate powder (having mean particle diameter of 0.4 mu m, 70 vol.%) in tetrachloroethane, was applied on the film. After applying the solution on one surface of the base layer using bar coating mode, a certain amount of convection was applied in an oven at 50 degrees C, and 80% of humidity to remove/dry tetrachloroethane. Finally, a coated layer of 5.1 mu m thickness was formed on the base layer to obtain microporous polyethylene composite film.