Separator for lithium secondary battery and manufacturing method therefor

1. A separator for a lithium secondary battery, comprising:

a porous polymer substrate having a plurality of pores, wherein the porous polymer substrate has a first outer surface configured to contact a positive or negative electrode of the lithium secondary battery;

a porous coating layer, wherein the porous coating layer has a second outer surface configured to contact the positive or negative electrode of the lithium secondary battery, wherein the first and second outer surfaces are on opposite sides of the separator; and

an emulsion binder layer disposed between the porous polymer substrate and the porous coating layer, wherein the surfaces of the emulsion binder layer are not configured to contact the positive or negative electrode.

2. The separator for a lithium secondary battery according to claim 1 , wherein the emulsion binder layer is formed from an emulsion solution in which a first polymer binder is dispersed in a solvent.

3. The separator for a lithium secondary battery according to claim 2 , wherein the first polymer binder is at least one selected from the group consisting of polymethylmethacrylate, poly(butyl methacrylate-co-methyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, and polyimide.

4. The separator for a lithium secondary battery according to claim 2 , wherein the first polymer binder is present in an amount of 0.1 to 5 wt % of the porous coating layer.

5. The separator for a lithium secondary battery according to claim 1 , wherein the emulsion binder layer is 10 to 1000 nm thick.

6. The separator for a lithium secondary battery according to claim 1 , wherein the organic particles are particles of at least one selected from the group consisting of polystyrene, 2-(((butoxyamino)carbonyl)oxy)ethylmethacrylate, 2-(diethylamino)ethylmethacrylate, 2-(dimethylamino)ethylmethacrylate, 3-(diethylamino)propylmethacrylate, 3-(dimethylamino)propylmethacrylate, methyl 2-acetoamidomethacrylate, 2-methacrylamidoglycolic acid, 2-methacrylamido-2-methyl-1-propanesulfonic acid, (3-methacrylamidopropyl)trimethyl ammonium chloride, N-methacryloylamido-ethoxyethanol, 3-methacryloyl amino-1-propanol, N-(butoxymethyl) methacryloamide, N-tert-butylmethacrylamide, diacetonemethacrylamide, N,N-dimethylmethacrylamide, N-(isobutoxymethyl)acrylamide, N-(isopropyl)methacrylamide, methacrylamide, N-phenylmethacrylamide, N-(tris(hydroxymethyl)methyl)methacrylamide, N—N′-(1,3-phenylene)dimaleimide, N—N′-(1,4-phenylene)dimaleimide, N—N′-(1,2-dihydroxyethylene)bisacrylamide, N—N′(1,4-phenylene)dimaleimide, N—N′-(1,2-dihydroxyethylene)bisacrylamide, N—N′-ethylenebismethacrylamide, and N-vinylpyrrolidinone.

7. The separator for a lithium secondary battery according to claim 1 , wherein the inorganic particles are inorganic particles having a dielectric constant of 5 or greater, inorganic particles having ability to transport lithium ion, or their mixtures.

8. The separator for a lithium secondary battery according to claim 1 , wherein the inorganic particles are at least one selected from the group consisting of SiO 2 , Al 2 O 3 , TiO 2 , BaTiO 3 , Li 2 O, LiF, LiOH, Li 3 N, BaO, Na 2 O, Li 2 CO 3 , CaCO 3 , LiAlO 2 , SrTiO 3 , SnO 2 , CeO 2 , MgO, NiO, CaO, ZnO, ZrO 2 , SiC, and their derivatives and their mixtures.

9. The separator for a lithium secondary battery according to claim 1 , wherein the porous coating layer further comprises a second polymer binder.

10. The separator for a lithium secondary battery according to claim 9 , wherein the second polymer binder is at least one copolymer selected from the group consisting of acrylonitrile-co-maleic anhydride, acrylonitrile-co-vinylalcohol, cyanoethylene-co-vinylalcohol, cyanoethylene-co-cellulose, cyanoethylene-co-sucrose, acrylonitrile-co-acrylic acid, acrylonitrile-co-maleic anhydride, acrylate-co-acrylic acid, and acrylate-co-maleic anhydride.

11. A method for manufacturing a separator for a lithium secondary battery, comprising:

coating an emulsion binder solution on a surface of a porous polymer substrate to form an emulsion binder layer on the surface of the porous polymer substrate, where the emulsion binder solution comprises a first polymer binder dispersed in a solvent; and

forming a porous coating layer on a surface of the emulsion binder layer that is opposite the porous polymer substrate, wherein the porous coating layer comprising a second polymer binder and at least one of inorganic particles or organic particles,

wherein outer surfaces of the porous polymer substrate and porous coating layer are configured to contact a positive or negative electrode of the lithium secondary battery, and

wherein the surfaces of the emulsion binder layer are not configured to contact the positive or negative electrode.

12. A lithium secondary battery comprising:

a positive electrode, a negative electrode, and the separator of claim 1 interposed between the positive electrode and the negative electrode.