Separator, manufacturing method of the same, and electrochemical device having the same

1. An electrochemical device comprising:

a cathode, an anode, a separator interposed between the cathode and the anode, and an electrolyte solution, wherein the separator comprises:

a porous composite having a porous substrate and a first porous coating layer formed on at least one surface of the porous substrate, wherein the first porous coating layer comprises a mixture of inorganic particles and a first binder polymer wherein the inorganic particles are immobilized by the first binder polymer, the first porous coating layer having pores defined by interstitial volumes between the inorganic particles; and

a second porous coating layer formed on a first surface of the porous composite wherein the second porous coating layer comprises a mixture of cathode active material particles, a second binder polymer and a first conductive material; and

a third porous coating layer formed on a second surface of the porous composite wherein the third porous coating layer comprises a mixture of anode active material particles, a third binder polymer and a second conductive material.

2. The electrochemical device according to claim 1 , wherein the separator further comprises a fourth porous coating layer formed on the surface of the second porous coating layer, the surface of the third porous coating layer or the surfaces of both the second porous coating layer and the third porous coating layer, wherein the fourth porous coating layer consists of a fourth binder polymer.

3. The electrochemical device according to claim 1 , wherein the cathode active material particles are selected from the group consisting of LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , LiCoPO 4 , LiFePO 4 , LiNiMnCoO 2 , LiNi 1-x-y-z Co x M1 y M2 z O 2 (wherein, M1 and M2 are each independently selected from the group consisting of Al, Ni, Co, Fe, Mn, V, Cr, Ti, W, Ta, Mg and Mo, x, y and z are each independently an atomic fraction of elements consisting of an oxide, and 0≦x<0.5, 0≦y<0.5, 0≦z<0.5, and x+y+z<1), and a mixture thereof.

4. The electrochemical device according to claim 1 , wherein the anode active material particles are selected from the group consisting of natural graphite, artificial graphite, a carbon-based material, LiTi 2 O 4 , silicon (Si), tin (Sn) and a mixture thereof.

5. The electrochemical device according to claim 1 , wherein the cathode active material particles are made of LiFePO 4 and the anode active material particles are made of LiTi 2 O 4 .

6. The electrochemical device according to claim 1 , wherein the first conductive material and the second conductive material are each independently selected from the group consisting of carbon black, acetylene black, Ketjen Black, Super P, carbon natotubes and a mixture thereof.

7. The electrochemical device according to claim 1 , wherein the inorganic particles are selected from the group consisting of inorganic particles having a dielectric constant of 5 or higher, inorganic particles having the ability to transport lithium ions, and a mixture thereof.

8. The electrochemical device according to claim 7 , wherein the inorganic particles having a dielectric constant of 5 or higher are selected from the group consisting of BaTiO 3 , Pb(Zr x ,Ti 1-x )O 3 (PZT, 0<x<1), Pb 1-x La x Zr 1-y Ti y O 3 (PLZT), (1−x)Pb(Mg 1/3 Nb 2/3 )O 3 -xPbTiO 3 (PMN-PT, 0<x<1), 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, TiO 2 inorganic particles and a mixture thereof.

9. The electrochemical device according to claim 7 , wherein the inorganic particles having the ability to transport lithium ions are 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 nitride (Li x N y , 0<x<4, 0<y<2), SiS 2 type glass (Li x Si y S z , 0<x<3, 0<y<2, 0<z<4), P 2 S 5 type glass (Li x P y S z , 0<x<3, 0<y<3, 0<z<7) particles, and a mixture thereof.

10. The electrochemical device according to claim 1 , wherein the first binder polymer, the second binder polymer and the third binder polymer are each independently selected from the group consisting of polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, and a mixture thereof.

11. The electrochemical device according to claim 2 , wherein the fourth binder polymer is selected from the group consisting of polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, and a mixture thereof.

12. The electrochemical device according to claim 1 , wherein the porous substrate is made of a polyolefin-based polymer.

13. The electrochemical device according to claim 1 , wherein the porous substrate has a thickness of 1 to 100 μm.

14. The electrochemical device according to claim 1 , wherein the porous substrate has a pore size of 0.01 to 50 μm and a porosity of 10 to 95%.

15. The electrochemical device according to claim 1 , wherein the first porous coating layer has a thickness of 0.01 to 20 μm.

16. The electrochemical device according to claim 1 , wherein the second porous coating layer and the third porous coating layer have each independently a thickness of 0.01 to 20 μm.

17. The electrochemical device according to claim 2 , wherein the fourth porous coating layer has a thickness of 0.01 to 10 μm.

18. The electrochemical device according to claim 1 , which is a lithium secondary battery.