SEPARATOR FOR LITHIUM SECONDARY BATTERY AND LITHIUM SECONDARY BATTERY INCLUDING THE SAME

A separator for a lithium secondary battery and a lithium secondary battery including the separator, including a porous polymer substrate; and a porous coating layer on at least one surface of the porous polymer substrate. The porous coating layer includes first inorganic particles surface-treated with a polyphenol-containing compound, second inorganic particles surface-treated with an organic acid, and a binder polymer. The first inorganic particles have an average particle diameter of 100 nm to 700 nm, and the second inorganic particles have an average particle diameter of 30 nm to 80 nm. The separator for a lithium secondary battery uses two types of surface-treated inorganic particles having a different average particle diameter. Therefore, the inorganic particles have improved dispersibility, and the separator has high thermal safety and can prevent separation of the inorganic particles.