Separator and electrochemical device having the same

A method of preparing a separator, comprising:

• providing a planar and porous substrate having multiple pores;
• providing a slot-die comprising a slot section and a slide section;
• and
• coating a first slurry on at least one surface of the porous substrate through the slot section to form a porous coating layer, while continuously coating a second slurry on the porous coating layer through the slide section adjacent to the slot section only by the force of gravity to form a layer for adhesion with an electrode,
• wherein the first slurry for forming the porous coating layer comprises inorganic particles, a first binder polymer and a first solvent,
• wherein the second slurry for forming the layer for adhesion comprises a second binder polymer and a second solvent,
• wherein the first binder polymer and the second binder polymer are each independently selected from polyvinylidene fluoride-co-hexafluoro propylene, polyvinylidene fluoride-co-trichloro ethylene, polyvinylidene fluoride-co-chlorotrifluoro ethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinylalcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyimide or a mixture thereof,
• wherein the first slurry and the second slurry each independently have a viscosity of 10 to 20 cp,
• wherein the first slurry is discharged at a rate faster than that of the second slurry,
• wherein the layer for adhesion has a thickness of 0.0005 μm to 1 μm, and
• wherein the slide section is inclined to form an angle (θ) of 10 to 60° with the slot section.