| abstract |
A porous substrate having pores; And an organic / inorganic composite separator coated on at least one surface of the porous substrate, the porous active layer including a mixture of inorganic particles and a binder polymer. The porous active layer has a composition morphology heterogeneity in the thickness direction in which the content ratio of the binder polymer / inorganic particles present in the surface portion is greater than the content ratio of the binder polymer / inorganic particles present therein. The organic / inorganic composite separator introduces a porous active layer having a heterogeneous morphology in which the content ratio of the binder polymer / inorganic particles in the surface layer is larger than the content ratio therein, thereby peeling and scratching the porous active layer. It can increase the resistance to scratch and improve the lamination characteristic with the electrode. As a result, the problem that the inorganic particles in the porous active layer are detached during the assembly of the electrochemical device can be improved, thereby improving battery safety and performance. |