Organic/inorganic composite porous film and electrochemical device prepared thereby

A lithium secondary battery comprising:

• a cathode;
• an anode;
• an electrolyte;
• and
• a separator comprising:
• a porous substrate, which is not a cathode and/or an anode, and an organic/inorganic composite porous film coated directly on a surface of the porous substrate, the organic/inorganic composite porous film consisting of:
• a binder polymer disposed on inorganic particles and interconnecting the inorganic particles to each other;
• and
• interstitial volumes defined by the interconnected inorganic particles,
• wherein said interstitial volumes defined by the interconnected inorganic particles directly form a uniform pore structure 3-dimensionally throughout the organic/inorganic composite porous film,
• wherein the inorganic particles have a dielectric constant of 5 or more,
• wherein the inorganic particles are at least one selected from the group consisting of BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb1-xLaxZr1-yTiyO3 (PLZT), Pb(Mg1/3Nb2/3)O3—PbTiO3 (PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, NiO, ZnO, and Y2O3,
• wherein the binder polymer consists of one or more selected from the group consisting of polyvinylidene fluoride-co-trichloroethylene, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethyl polyvinylalcohol, cyanoethylcellulose, and cyanoethylsucrose pullulan,
• wherein the organic/inorganic composite porous film is obtained by coating a mixture of the inorganic particles and the binder polymer on the surface of the porous substrate, and
• wherein the organic/inorganic composite porous film is not formed by coating the mixture of the inorganic particles and the binder polymer on a surface of a cathode or an anode.