A separator comprising: a porous substrate; a porous organic-inorganic coating layer formed on at least one surface of the porous substrate and comprising a mixture of inorganic particles and a first binder polymer, the first binder polymer containing a copolymer comprising (a) a first monomer unit comprising either at least one amine group or at least one amide group or both in the side chain thereof and (b) a (meth)acrylate having a C 1 -C 14 alkyl group as a second monomer unit; and an organic coating layer formed by dispersing a second binder polymer on the surface of the organic-inorganic coating layer, leaving scattered uncoated areas, wherein the first monomer unit is selected from the group consisting of 2-(((butoxyamino)carbonyl)oxy)ethyl (meth)acrylate, 2-(diethylamino)ethyl (meth)acrylate, 2-(dimethylamino)ethyl (meth)acrylate, 3-(diethylamino)propyl (meth)acrylate, 3-(dimethylamino)propyl(meth)acrylate, methyl 2-acetamido(meth)acrylate, 2-(meth)acrylamidoglycolic acid, 2-(meth)acrylamido-2-methyl-1-propanesulfonic acid, (3-(meth)acrylamidopropyl)trimethylammonium chloride, N-(meth)acryloylamido-ethoxyethanol, 3-(meth)acryloylamino-1-propanol, N-(butoxymethyl)(meth)acrylamide, N-tert-butyl(meth)acrylamide, diacetone(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-(isobutoxymethyl)acrylamide, N-(isopropyl)(meth)acrylamide, (meth)acrylamide, N-phenyl(meth)acrylamide, N-(tris(hydroxymethyl)methyl)(meth)acrylamide, N,N'-(1,2-dihydroxyethylene)bisacrylamide, N,N'-ethylenebis(meth)acrylamide, and mixtures thereof, and wherein the second monomer unit is selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, tetradecyl (meth)acrylate, and mixtures thereof. a porous substrate; a porous organic-inorganic coating layer formed on at least one surface of the porous substrate and comprising a mixture of inorganic particles and a first binder polymer, the first binder polymer containing a copolymer comprising (a) a first monomer unit comprising either at least one amine group or at least one amide group or both in the side chain thereof and (b) a (meth)acrylate having a C 1 -C 14 alkyl group as a second monomer unit; and an organic coating layer formed by dispersing a second binder polymer on the surface of the organic-inorganic coating layer, leaving scattered uncoated areas, wherein the first monomer unit is selected from the group consisting of 2-(((butoxyamino)carbonyl)oxy)ethyl (meth)acrylate, 2-(diethylamino)ethyl (meth)acrylate, 2-(dimethylamino)ethyl (meth)acrylate, 3-(diethylamino)propyl (meth)acrylate, 3-(dimethylamino)propyl(meth)acrylate, methyl 2-acetamido(meth)acrylate, 2-(meth)acrylamidoglycolic acid, 2-(meth)acrylamido-2-methyl-1-propanesulfonic acid, (3-(meth)acrylamidopropyl)trimethylammonium chloride, N-(meth)acryloylamido-ethoxyethanol, 3-(meth)acryloylamino-1-propanol, N-(butoxymethyl)(meth)acrylamide, N-tert-butyl(meth)acrylamide, diacetone(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-(isobutoxymethyl)acrylamide, N-(isopropyl)(meth)acrylamide, (meth)acrylamide, N-phenyl(meth)acrylamide, N-(tris(hydroxymethyl)methyl)(meth)acrylamide, N,N'-(1,2-dihydroxyethylene)bisacrylamide, N,N'-ethylenebis(meth)acrylamide, and mixtures thereof, and wherein the second monomer unit is selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, tetradecyl (meth)acrylate, and mixtures thereof.