Sealer for secondary battery and secondary battery including sealer

A secondary battery comprising:

• an electrode assembly;
• a case accommodating the electrode assembly, the case having a through-hole on a surface of the case to allow fluid injection or discharge;
• and
• a sealer comprising a self-restoring material, wherein the sealer seals the through-hole of the case.

A secondary battery comprising:

• an electrode assembly;
• a case accommodating the electrode assembly, the case having a through-hole formed on a surface of the case to discharge gas from an inside of the case to an outside of the case;
• and
• a sealer sealing the through-hole of the case, the sealer comprising:
• a self-restoring material comprising isotactic polypropylene, polyvinyl chloride, polyurethane, polyrotaxane, polyester, epoxy resin, or acrylic ester;
• and
• a porous film having a mesh structure,
• wherein the sealer further comprises an inorganic filler that is heat-resistant or a low-water-vapor permeability resin that reduces an amount of gas flowing through the sealer, and
• wherein the self-restoring material has a viscosity allowing a movement of molecules contained in the self-restoring material such that a deformed geometry of the sealer recovers after gas generated inside the case passes through the sealer.