Separator and electrochemical device including the same

A separator comprising:

• a porous polymer substrate having a plurality of pores;
• and
• a porous coating layer on at least one surface of the porous polymer substrate,
• wherein the porous coating layer comprises inorganic particles, core-shell polymer particles having a core portion and a shell portion surrounding the core portion, and a binder polymer positioned on a whole or a part of a surface of the inorganic particles and core-shell polymer particles to connect and fix the inorganic particles and core-shell polymer particles with one another,
• wherein the core portion has a glass transition temperature, Tg, higher than a glass transition temperature, Tg, of the shell portion in the core-shell polymer particles,
• the core-shell polymer particles have an average glass transition temperature, Tg, of −5° C. to 80° C.,
• a ratio of an average diameter of the core-shell polymer particles to an average diameter of the inorganic particles is 80% to 200%, and
• a ratio of an average diameter of the core portion to an average diameter of the core-shell type polymer particles is 30% to 60%.