Organic/inorganic composite porous film and electrochemical device prepared thereby

Abstract

Disclosed is an organic/inorganic composite porous film comprising: (a) inorganic particles; and (b) a binder polymer coating layer formed partially or totally on surfaces of the inorganic particles, wherein the inorganic particles are interconnected among themselves and are fixed by the binder polymer, and interstitial volumes among the inorganic particles form a micropore structure. A method for manufacturing the same film and an electrochemical device including the same film are also disclosed. An electrochemical device comprising the organic/inorganic composite porous film shows improved safety and quality.

1 . An organic/inorganic composite porous film, which comprises:
 (a) inorganic particles; and   (b) a binder polymer coating layer formed partially or totally on surfaces of the inorganic particles, wherein the inorganic particles are interconnected among themselves and are fixed by the binder polymer, and interstitial volumes among the inorganic particles form a micropore structure.   
     
     
         2 . The film according to  claim 1 , wherein the inorganic particles are at least one selected from the group consisting of: (a) inorganic particles having a dielectric constant of 5 or more; and (b) inorganic particles having lithium ion conductivity. 
     
     
         3 . The film according to  claim 2 , wherein the inorganic particles having a dielectric constant of 5 or more are 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 , Y 2 O 3 , Al 2 O 3 , TiO 2  or SiC. 
     
     
         4 . The film according to  claim 2 , wherein the inorganic particles having lithium ion conductivity are at least one selected from the group consisting of: lithim 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  type glass (Li x Si y S z , 0<x<3, 0<y<2, 0<z<4) and P 2 S 5  type glass (Li x P y S z , 0<x<3, 0<y<3, 0<z<7). 
     
     
         5 . The film according to  claim 1 , wherein the inorganic particles have a size of between 0.001 μm and 10 μm. 
     
     
         6 . The film according to  claim 1 , wherein the inorganic particles are present in the mixture of inorganic particles with the binder polymer in an amount of 50-99 wt. % based on 100 wt. % of the mixture. 
     
     
         7 . The film according to  claim 1 , wherein the binder polymer has a glass transition temperature (T g ) of between −200° C. and 200° C. 
     
     
         8 . The film according to  claim 1 , wherein the binder polymer has a solubility parameter of between 15 and 45 MPa 1/2 . 
     
     
         9 . The film according to  claim 1 , wherein the binder polymer is at least one selected from the group consisting of polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethyl polyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxymetyl cellulose, acrylonitrile-styrene-butadiene copolymer and polyimide. 
     
     
         10 . The film according to  claim 1 , which has a pore size of between 0.001 and 10 μm. 
     
     
         11 . The film according to  claim 1 , which has a porosity of between 5% and 95%. 
     
     
         12 . The film according to  claim 1 , which has a thickness of between 1 and 100 μm. 
     
     
         13 . An electrochemical device comprising:
 (a) a cathode;   (b) an anode;   (c) an organic/inorganic composite porous film, which comprises: (i) inorganic particles; and (ii) a binder polymer coating layer formed partially or totally on surfaces of the inorganic particles, wherein the inorganic particles are interconnected among themselves and are fixed by the binder polymer, and interstitial volumes among the inorganic particles form a micropore structure; and   (d) an electrolyte.   
     
     
         14 . The electrochemical device according to  claim 13 , wherein the inorganic particles are at least one selected from the group consisting of: (a) inorganic particles having a dielectric constant of 5 or more; and
 (b) inorganic particles having lithium ion conductivity.   
     
     
         15 . The electrochemical device according to  claim 13 , wherein the binder polymer has a solubility parameter of between 15 and 45 MPa 1/2 . 
     
     
         16 . The electrochemical device according to  claim 13 , which is a lithium secondary battery. 
     
     
         17 . The electrochemical device according to  claim 13 , which further comprises a microporous separator. 
     
     
         18 . The electrochemical device according to  claim 17 , wherein the microporous separator is a polyolefin-based separator, or at least one porous substrate having a melting point of 200° C. or higher, selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetherether ketone, polyether sulfone, polyphenylene oxide, polyphenylene sulfidro and polyethylene naphthalene. 
     
     
         19 . A method for manufacturing an organic/inorganic composite porous film according to  claim 1 , which comprises the steps of:
 (a) dissolving a binder polymer into a solvent to form a polymer solution;   (b) adding inorganic particles to the polymer solution obtained from step (a) and mixing them; and   (c) coating the mixture of inorganic particles with binder polymer obtained from step (b) on a substrate, followed by drying, and then detaching the substrate.