Separator, lithium secondary battery including separator, and manufacturing method therefor

A method for manufacturing a lithium secondary battery, comprising the steps of:

• (S1) preparing a slurry comprising (a) inorganic particles comprising at least one hydroxyl group or inorganic particles surface-treated with hydroxyl groups, (b) a crosslinkable binder polymer which comprises a homopolymer comprising repeating units of a polyvinylidene fluoride-containing monomer containing at least one acrylate (CH2═CHCOO—) group and a homopolymer comprising repeating units of an acrylate monomer comprising at least one isocyanate (—NCO) group, and (c) a solvent;
• (S2) applying the slurry on a porous polymer substrate, followed by drying, to prepare a preliminary separator having a porous coating layer on the porous polymer substrate;
• (S3) manufacturing a battery comprising the preliminary separator;
• and
• (S4) activating the battery,
• wherein the inorganic particles and the crosslinkable binder polymer comprising isocyanate and acrylate groups undergo a crosslinking reaction during the activation step to form urethane crosslinking.