TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The support layer is high density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, high crystalline polypropylene, polyethylene-propylene copolymer, polyethylene-butylene copolymer, polyethylene-hexene copolymer, polyethylene-octene copolymer, polystyrene-butylene-styrene copolymer, polystyrene-ethylene-butylene-styrene copolymer, polystyrene, polyphenylene oxide, polysulfone, polycarbonate, polyester, polyamide, polyurethane, polyacrylate, polyvinylidene chloride, polyvinylidene fluoride, polysiloxane, polyolefin, ionomer, polymethylpentene, hydrogenated oligocyclopentadiene, and/or its derivatives.A component of the active layers is polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, polypropylene oxide, polybutylene oxide, polyurethane, polyacrylonitrile, polyacrylate, polyacrylic acid, polyamide, polyacrylamide, polyvinylacetate, polyvinylpyrrolidone, polytetraethylene glycol diacrylate, polysulfone, polyphenylene oxide, polycarbonate, polyester, polyvinylidene chloride, polysiloxane, polyolefin ionomer, and/or its derivative.The high crystalline polypropylene has a density of at least 0.905 g/cm3, a m. pt. of at least 164degreesC, a crystallization temperature of at least 125degreesC, a crystallinity of at least 50%, an isotacticity of at least 96%, and an atactic fraction of upto 5%. The composite membrane has an air permeability of upto 7000 sec/100 cm3, and a wet-out rate of upto 30 seconds.The support layer has a pore size of 0.001-10 micro-m, and a thickness of 1-50 micro-m. The active layer has a pore size of 10 micro-m, and a thickness of 0.01-20 micro-m.Preferred Method: The precursor film is coated with the polymer solution by dip-coating. The drying step is performed at a relative humidity of 1-100%, under saturated vapor pressure, or under a gas atmosphere consisting of nitrogen, oxygen, carbon dioxide or air atmosphere. The irradiating of ion beams is performed under a vacuum of 10 power -1-10 power -6 Torr, by activation of electrons and a gas consisting of hydrogen, helium, oxygen, nitrogen, carbon dioxide, air, fluorine, neon, argon, krypton, and/or nitrous oxide, so that the gas has an energy of 0.01-10 power 6 keV, or under a gas atmosphere consisting of helium, hydrogen, nitrogen, ammonia, carbon monoxide, carbon dioxide, chlorofluoro methane, methane, and/or nitrous oxide atmospheres. The irradiation amount of the ion beams is 10 power 5-10 power 20 ions/cm2. The flow rate of the reactive gas is 0.5-20 ml/minute. The concentration of the polymer solution is at least 0.01 wt.%    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compounds: A solvent for the component of the active layers is 1-methyl-2-pyrrolidone, acetone, ethanol, n-propanol, n-butanol, n-hexane, cyclohexanol, acetic acid, ethyl acetate, diethyl ether, dimethyl formamide, dimethylacetamide, dioxane, tetrahydrofuran, dimethyl sulfoxide, cyclohexane, benzene, toluene, xylene, and/or water. EXAMPLE - A precursor film was prepared from high crystalline polyethylene. The precursor film was annealed at 125degreesC for 1 hour. After annealing, a solution prepared by dissolving Kynar461 was dip coated on both sides of the precursor film. The coated film was monoaxially low temperature stretched to 50% of the stretching ratio, and then monoaxially high temperature stretched to 100% of the stretching ratio. This was then heat-set at 120degreesC under tension for 10 minutes, preparing a composite membrane. The composite membrane of the invention showed an air permeability of 620 sec/100 cm3, an interfacial adhesion strength of 240degreesC, and a wet-out rate of an electrolyte of 9 seconds.