Method of preparing separator for lithium secondary battery, separator prepared therefrom, and lithium secondary battery comprising the same

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

(S1) bringing polymer particles into electric charging to obtain electrically charged polymer particles;

(S2) transferring the electrically charged polymer particles on at least one surface of an inversely electrically charged porous polymer substrate to form an electrode-adhesion layer whose area ranges from 1 to 30% based on a total area of the porous polymer substrate; and

(S3) fixing the electrode-adhesion layer with heat and pressure,

wherein a solvent is not used to form the electrode-adhesion layer.

2. The method of claim 1 , wherein the porous polymer substrate is selected from the group consisting of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalate, and a mixture thereof.

3. The method of claim 1 , wherein the polymer particles are selected from the group consisting of polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride-co-chlorotrifluoroethylene, polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, alginate, carboxyl methyl cellulose and a mixture thereof.

4. The method of claim 1 , wherein the electrode-adhesion layer has a thickness of 0.001 to 5 μm.

5. The method of claim 1 , wherein the electrode-adhesion layer is formed in at least one selected from line, wave, cross and random patterns.

6. The method of claim 1 , wherein the electrode-adhesion layer is formed on each of both surfaces of the porous polymer substrate, and the electrode-adhesion layers formed each have patterns being asymmetric to each other.

7. The method of claim 1 , wherein the electrode-adhesion layer is formed on each of both surfaces of the porous polymer substrate by applying the polymer particles in different amounts.

8. The method of claim 1 , wherein the fixing step is carried out at a temperature of 60 to 180° C. and a pressure of 1 to 300 kgf/cm 2 .

9. A method of preparing a separator for a lithium secondary battery, comprising:

(S1) forming a porous coating layer comprising inorganic particles on at least one surface of an electrically charged porous polymer substrate;

(S2) bringing polymer particles into electric charging to obtain inversely electrically charged polymer particles;

(S3) transferring the electrically charged polymer particles on the porous coating layer to form an electrode-adhesion layer whose area ranges from 1 to 30% based on a total area of the porous coating layer; and

(S4) fixing the electrode-adhesion layer with heat and pressure,

wherein a solvent is not used to form the electrode-adhesion layer.

10. The method of claim 9 , 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, or a mixture thereof.

11. The method of claim 10 , wherein the inorganic particles having a dielectric constant of 5 or higher are selected from the group consisting of SrTiO 3 , SnO 2 , CeO 2 , MgO, NiO, CaO, ZnO, ZrO 2 , SiO 2 , Y 2 O 3 , Al 2 O 3 , AlOOH, Al(OH) 3 , TiO 2 , SiC, 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, 0<x<1, 0<y<1), (1-x)Pb(Mg 1/3 Nb 2/3 )O 3 -xPbTiO 3 (PMN-PT, 0<x<1), HfO 2 inorganic particles and a mixture thereof.

12. The method of claim 10 , 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) inorganic particles, and a mixture thereof.

13. The method of claim 9 , wherein the inorganic particles have an average diameter of 0.001 to 100 μm.

14. The method of claim 9 , wherein the porous coating layer has a thickness of 1 to 100 μm.

15. The method of claim 9 , wherein the electrode-adhesion layer has a thickness of 0.001 to 5 μm.

16. The method of claim 9 , wherein the electrode-adhesion layer is formed in at least one selected from line, wave, cross and random patterns.

17. The method of claim 9 , wherein the porous coating layer is formed on each of both surfaces of the porous polymer substrate and the electrode-adhesion layer is formed on each of the porous coating layers, and the electrode-adhesion layers formed each have patterns being asymmetric to each other.

18. The method of claim 9 , wherein the porous coating layer is formed on each of both surfaces of the porous polymer substrate and the electrode-adhesion layer is formed on each of the porous coating layers by applying the polymer particles in different amounts.

19. The method of claim 9 , wherein the fixing step is carried out at a temperature of 60 to 180° C. and a pressure of 1 to 300 kgf/cm 2 .