Separator and application thereof

A separator formed by hydrolysis of a resin film, wherein the resin film comprises:

• a non-hydrolyzable organic polymer comprising polybenzimidazole, polybenzoxazole, polybenzothiazole, polyetherketone, polyphenylene ether, polyethersulfone, polysulfone, polyphenylene sulfide, polypropylene, polyethylene, polystyrene or a combination thereof;
• and
• a hydrolyzable organic polymer being hydrolyzable with treatment of at least one of an aqueous acid solution, an aqueous alkaline solution and pure water,
• wherein a content of the hydrolyzable organic polymer ranges from 10 parts by weight to 70 parts by weight, based on 100 parts by weight of the resin film, and the hydrolyzable organic polymer includes a repeating unit represented by formula (1):
• wherein X1 is a tetravalent group comprising at least one aromatic or alicyclic group;
• Y1 is a divalent group comprising at least one aromatic or alicyclic group, and at least one of X1 and Y1 comprises at least one functional group structure among an ester bond, an amide bond, a sulfonic acid group, a phosphoric acid group, a carboxylic acid group, a hydroxyl group and a nitro group.