Separator for Lithium Secondary Battery and Lithium Secondary Battery Including the Same

A separator and a lithium secondary battery including the same are disclosed herein. In some embodiments, a separator includes a porous polymer substrate; and an organic/inorganic composite porous layer disposed on at least one surface of the porous polymer substrate and including a nanofiber scaffold, inorganic particles and a binder polymer, wherein, in the organic/inorganic composite porous layer, the inorganic particles are present in voids of the nanofiber scaffold, the inorganic particles have a BET specific surface area of 20 m2/g to 75 m2/g, and the binder polymer is present in an amount of 2 wt % to 5 wt % based on the total weight of the organic/inorganic composite porous layer.