A separator including a porous substrate, and a porous coating layer formed on at least one surface of the porous substrate and including a mixture of inorganic particles and a binder polymer. A continuous or discontinuous patterned layer is formed on the surface of the porous coating layer to allow an electrolyte solution to permeate therethrough. The continuous or discontinuous patterned layer may be formed with continuous grooves to allow an electrolyte solution to permeate therethrough. Due to this structure, the wettability of the separator with an electrolyte solution is improved, shortening the time needed to impregnate the electrolyte solution into the separator.