A composition to form a porous insulating layer on an active material layer on a main surface of a current collector current collector is provided. The active material layer includes an active material to electrochemically intercalate and deintercalate lithium ions and an active material layer binder, the composition to form the porous insulating layer includes a solvent including an organic solvent, an insulating inorganic particle, and a binder, and the binder is a polymer obtained by polymerization of monomers including about 30 wt % to about 60 wt % of an aromatic vinyl compound, about 20 wt % to about 69 wt % of (meth)acrylic acid ester, about 5 wt % to about 35 wt % of (meth)acrylic acid ester including a hydroxy group or an ether group, and about 1 wt % to about 10 wt % of a vinyl compound including an acidic functional group, based on a total weight of the binder.