Separator including coating layer with ethylenically unsaturated binder, and secondary battery including polymer network formed by gel polymer electrolyte and ethylenically unsaturated binder in coating layer of separator

A separator for a lithium secondary battery, the separator comprising:

• a substrate;
• and
• a coating layer formed on a surface of the substrate, wherein
• the coating layer includes an organic binder and inorganic particles, and
• the organic binder contains an ethylenically unsaturated group positioned at an end portion or a side portion of a polymer including at least one unit selected from the group consisting of Formulas X-1, X-2, and X-4:
• in Formula X-1, the ml is an integer of 1 to 100,
• in Formula X-2, the m2 and the m3 are each independently an integer of 1 to 100,
• in Formula X-4, the m5 is an integer of 1 to 100,
• wherein the ethylenically unsaturated group is at least one selected from the group consisting of a vinyl group, an acryloxy group and a methacryloxy group, and
• wherein the inorganic particles is included in an amount of 60 parts by weight to 99 parts by weight based on 100 parts by weight of the coating layer.