Abstract: An electrode assembly includes a negative electrode having an extension portion. The electrode assembly includes a positive electrode configured such that a positive electrode tab protrudes from one outer end of the positive electrode and a positive electrode active material is applied to a positive electrode current collector, a negative electrode configured such that a negative electrode tab protrudes from one outer end of the negative electrode and a negative electrode active material is applied to a negative electrode current collector, and a separator located between the positive electrode and the negative electrode. An extension portion is formed at an edge of the negative electrode so as to extend therefrom by a predetermined length, and a bent portion is formed at an edge of the separator. The bent portion is bent by a predetermined angle so as to wrap a part of a side surface of the positive electrode.

Abstract: A secondary battery according to the present invention comprises a pouch comprising an accommodation part accommodate the electrode assembly, a gas pocket part collecting a gas generated in the accommodation part, an edge sealing part provided along each of edge surfaces of the accommodation part and the gas pocket part, and a corner sealing part provided on each of both ends of a boundary between the accommodation part and the gas pocket part to support the electrode assembly accommodated in the accommodation part, wherein the corner sealing part comprises a full-width support surface supporting one end in a full-width direction of the electrode assembly, which faces the gas pocket part, and a full-length support surface provided between the full-width support surface and the edge sealing part, having a width greater than that of the full-width support surface, and supporting one end in a full-length direction of the electrode assembly, which faces the edge sealing part, and the full-length support surface,