NOVELTY - A separator (10) comprises a porous substrate (1) having several pores; and a porous coating layer formed on at least one surface of the porous substrate. The coating layer is made of a mixture of several inorganic particles (3) and a binder polymer (5). The binder polymer includes a first polyvinylidene fluoride-based copolymer having solubility of greater than or equal to 25 wt.% with respect to acetone at 35 degrees C; a second polyvinylidene fluoride-based copolymer having solubility of less than or equal to 10 wt.% with respect to acetone at 35 degrees C; and a polymer having a cyano group.    USE - As separator useful in electrochemical device such as lithium secondary battery (claimed) and super capacitors, particularly middle or large batteries for electric vehicles or hybrid vehicles.    ADVANTAGE - The separator improves life span characteristics of electrochemical devices, and improves safety of an electrochemical device by solving the problem that inorganic particles in a porous coating layer formed on a porous substrate are disintercalated during an assembling process of the electrochemical device. The separator solves deterioration of life span characteristics of an electrochemical device, and also solves the problem of disintercalation of inorganic particles in the porous coating layer formed on a porous substrate during an assembling process of the electrochemical device, thus improving safety of the electrochemical device.    DETAILED DESCRIPTION - A separator (10) comprises a porous substrate (1) having several pores; and a porous coating layer formed on at least one surface of the porous substrate. The coating layer is made of a mixture of several inorganic particles (3) and a binder polymer (5). The binder polymer includes a first polyvinylidene fluoride-based copolymer (5-30 wt.%) having solubility of greater than or equal to 25 wt.% with respect to acetone at 35 degrees C; a second polyvinylidene fluoride-based copolymer (1-10 et.%) having solubility of less than or equal to 10 wt.% with respect to acetone at 35 degrees C; and a polymer having a cyano group (0.1-5 wt.%). The inorganic particles have a size of 0.001-10 mu m. The inorganic particles are selected from inorganic particles having a dielectric constant of greater than or equal to 5 and/or inorganic particles having lithium-ion transferring capability. An INDEPENDENT CLAIM is included for an electrochemical device, comprising a positive electrode, a negative electrode, and the separator interposed between the positive electrode and the negative electrode.    DESCRIPTION OF DRAWING(S) - The figure shows a sectional view of the separator.    Substrate (1)    Inorganic particles (3)    Binder polymer (5)    Separator (10)