SECONDARY BATTERY

PROBLEM TO BE SOLVED: To provide a secondary battery in which, when a cap plate is tied to a case, placement of the cap plate on an aperture plane of the case is induced and the cap plate is prevented from being excessively inserted.SOLUTION: A secondary battery according to one embodiment for the invention includes: an electrode assembly including a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode; a case including at least one groove formed in a ridge part of the aperture plane into which the electrode assembly is inserted; and a cap plate including at least one protrusion tied to at least one groove formed in the ridge part of the case. 【課題】ケースにキャッププレートを結合する時、ケースの開口面にキャッププレートの載置を誘導し、キャッププレートの過挿入を防止する二次電池を提供する。【解決手段】本発明の一実施形態にかかる二次電池は、第１電極、第２電極、および前記第１電極と前記第２電極との間に介在するセパレータを含む電極アセンブリと、前記電極アセンブリの挿入される開口面の稜部に形成された少なくとも１つの溝部を含むケースと、前記ケースの前記稜部に形成された前記少なくとも１つの溝部に結合される少なくとも１つの突出部を含むキャッププレートと、を含む。【選択図】図１