Organic/inorganic composite separator and electrochemical device containing the same

1. An organic/inorganic composite separator, which includes a porous substrate having a plurality of pores, and a porous coating layer formed on at least one surface of the porous substrate with a plurality of inorganic particles and a binder polymer,

wherein the binder polymer is a copolymer including:

(a) a first monomer unit having a contact angle to a water drop in the range from 0° to 49°; and

(b) a second monomer unit having a contact angle to a water drop in the range from 50° to 130°.

2. The organic/inorganic composite separator according to claim 1 ,

wherein the first monomer unit has a contact angle to a water drop in the range from 5° to 30°, and the second monomer unit has a contact angle to a water drop in the range from 70° to 120°.

3. The organic/inorganic composite separator according to claim 1 ,

wherein the first monomer unit has a molar ratio in the range from 1 to 20 mol % based on the entire copolymer.

4. The organic/inorganic composite separator according to claim 1 ,

wherein the copolymer has a contact angle to a water drop in the range from 30° to 80°.

5. The organic/inorganic composite separator according to claim 1 ,

wherein the first monomer unit is a monomer unit having at least one functional group selected from the group consisting of OH, COOH, MAH (maleic anhydride) and SO 3 H, and the second monomer unit is a monomer unit having at least one functional group selected from the group consisting of F, Cl, CN, acrylate, acetate and ester.

6. The organic/inorganic composite separator according to claim 1 ,

wherein the copolymer is a copolymer selected from the group consisting of acrylonitrile-maleic anhydride copolymer, acrylonitrile-vinylalcohol copolymer, cyanoethylene-vinylalcohol copolymer, cyanoethylene-cellulose copolymer, cyanoethylene-sucrose copolymer, acrylonitrile-acrylic acid copolymer, acrylonitrile-anhydrous maleic acid copolymer, acrylate-acrylic acid copolymer and acrylate-anhydrous malcic acid copolymer.

7. The organic/inorganic composite separator according to claim 1 ,

wherein the porous coating layer has a peeling force of 5 gf/cm or above.

8. The organic/inorganic composite separator according to claim 1 ,

wherein the inorganic particles have a size in the range from 0.001 to 10 μm.

9. The organic/inorganic composite separator according to claim 1 ,

wherein the inorganic particles are selected from the group consisting of inorganic particles having a dielectric constant of 5 or above, inorganic particles having lithium-ion transferring capability, or their mixtures.

10. The organic/inorganic composite separator according to claim 9 ,

wherein the inorganic particle having a dielectric constant of 5 or above is an inorganic particle selected from the group consisting of BaTiO 3 , Pb(Zr,Ti)O 3 (PZT), Pb 1−x La x Zr 1−y Ti y O 3 (PLZT), PB(Mg 3 Nb 2/3 )O 3 -PbTiO 3 (PMN-PT), hafnia (HfO 2 ), SrTiO 3 , SnO 2 , CeO 2 , MgO, NiO, CaO, ZnO, ZrO 2 , SiO 2 , Y 2 O 3 , Al 2 O 3 , SiC and TiO 2 .

11. The organic/inorganic composite separator according to claim 10 ,

wherein the inorganic particle having a dielectric constant of 5 or above is an piezoelectric inorganic particle selected from the group consisting of BaTiO 3 , Pb(Zr,Ti)O 3 (PZT), Pb 1−x La x Zr 1−y Ti y O 3 (PLZT), PB(Mg 3 Nb 2/3 )O 3 -PbTiO 3 (PMN-PT) and hafnia (HfO 2 ).

12. The organic/inorganic composite separator according to claim 9 ,

wherein the inorganic particle having lithium ion conductivity is an inorganic particle selected from the group consisting of lithium phosphate (Li 3 PO 4 ), lithium titanium phosphate (Li x Ti y (PO 4 ) 3 , 0<x<2, 0<y<3), lithium aluminum titanium phosphate (Li x Al y Ti z (PO 4 ) 3 , 0<x<2, 0<y<1, 0<z<3), (LiAlTiP) x O y type glass (0<x<4, 0<y<13), lithium lanthanum titanate (Li x La y TiO 3 , 0<x<2, 0<y<3), lithium germanium thiophosphate (Li x Ge y P z S w , 0<x<4, 0<y<1, 0<z<1, 0<w<5), lithium nitrides (Li x N y , 0<x<4, 0<y<2), SiS 2 (Li x Si y S z , 0<x<3, 0<y<2, 0<z<4) type glass, and P 2 S 5 (Li x P y S z , 0<x<3, 0<y<3, 0<z<7) type glass.

13. The organic/inorganic composite separator according to claim 1 ,

wherein a weight ratio of the inorganic particles and the binder polymer is in the range from 50:50 to 99:1.

14. The organic/inorganic composite separator according to claim 1 ,

wherein the porous coating layer has a thickness of 0.01 to 20 μm a pore size of 0.001 to 10 μm and a porosity of 10 to 90%.

15. The organic/inorganic composite separator according to claim 1 ,

wherein the porous substrate is a polyolefin porous substrate.

16. The organic/inorganic composite separator according to claim 1 ,

wherein the polyolefin porous substrate is famed using a polymer selected from the group consisting of polyethylene, polypropylene, polybutylene and polypentene.

17. The organic/inorganic composite separator according to claim 1 ,

wherein the porous substrate has a thickness of 5 to 50 μm, a pore size of 0.01 to 50 μm and a porosity of 10 to 95%.

18. An electrochemical device including a cathode, an anode, and a separator interposed between the cathode and the anode,

wherein the separator is the organic/inorganic composite separator defined in claim 1 .

19. The electrochemical device according to claim 18 , wherein the electrochemical device is a lithium secondary battery.