Abstract: A separator includes a non-woven fabric substrate having pores, fine thermoplastic powder located inside the pores of the non-woven fabric substrate, and a porous coating layer disposed on at least one surface of the non-woven fabric substrate. The fine thermoplastic powder has an average diameter smaller than that of the pores and a melting point lower than the melting or decomposition point of the non-woven fabric substrate. The porous coating layer includes a mixture of inorganic particles and a binder polymer whose melting point is higher than the melting or decomposition point of the fine thermoplastic powder. In the porous coating layer, the inorganic particles are fixedly connected to each other by the binder polymer and the pores are formed by interstitial volumes between the inorganic particles. Previous filling of the large pores of the non-woven fabric substrate with the fine thermoplastic powder makes the porous coating layer uniform.

Abstract: Disclosed is an electrochemical device. The electrochemical device includes: (a) a composite separator including a porous substrate, a first porous coating layer coated on one surface of the porous substrate, and a second porous coating layer coated on the other surface of the porous substrate; (b) an anode disposed to face the first porous coating layer; and (c) a cathode disposed to face the second porous coating layer. The first and second porous coating layers are each independently composed of a mixture including inorganic particles and a binder polymer. The first porous coating layer is thicker than the second porous coating layer. The electrochemical device has good thermal stability and improved cycle characteristics.

Abstract: Disclosed are a separator for a battery, which comprises a gel polymer layer formed on a substrate, the gel polymer layer including a plurality of three-dimensional open pores interconnected with each other, and an electrochemical device comprising the same separator. Also, disclosed is a method for preparing the gel polymer layer including a plurality of three-dimensional open pores interconnected with each other on a substrate.