Abstract: Disclosed are an electrode having a porous active coating layer, a manufacturing method thereof and an electrochemical device containing the same. The electrode having a porous active coating layer according to the present invention may be useful to enhance peeling and scratch resistances of the porous active layer and improve a lamination characteristic toward the porous active layer by introducing a porous active layer onto a porous substrate having pores, the porous active layer having heterogeneity of morphology toward a thickness direction in which a content ratio of the binder polymer/inorganic particles present in a surface layer is higher than that of the binder polymer/inorganic particles present inside the surface layer. Accordingly, the stability and performances of the battery can be improved at the same time since the detachment of the inorganic particles from the porous active layer may be reduced during the assembly process of the electrochemical device.

Abstract: An organic/inorganic composite separator includes (a) a polyolefin porous substrate having pores; and (b) a porous active layer containing a mixture of inorganic particles and a binder polymer, with which at least one surface of the polyolefin porous substrate is coated, wherein the porous active layer has a peeling force of 5 gf/cm or above, and a thermal shrinkage of the separator after being left alone at 150° C. for 1 hour is 50% or below in a machine direction (MD) or in a transverse direction (TD). This organic/inorganic composite separator solves the problem that inorganic particles in the porous active layer formed on the porous substrate are extracted during an assembly process of an electrochemical device, and also it may prevent an electric short circuit between cathode and anode even when the electrochemical device is overheated.