SECONDARY BATTERY WITH ENHANCED SEALING PERFORMANCE

Disclosed herein is a secondary battery having an electrode assembly placed in a prismatic container, wherein an upper part of the inside of an electrolyte injection hole formed in a base plate mounted to an open upper end of the prismatic container is configured to have a chamfered structure in which the diameter of the electrolyte injection hole is gradually decreased downward, a lower part of the inside of the electrolyte injection hole is configured to have a non-chamfered structure, the chamfered structure is formed in an irregular shape to increase the length of an electrolyte leakage route along which an electrolyte leaks out of the secondary battery, and, when a sealing member is pressed into the electrolyte injection hole, the sealing member is deformed so as to correspond to an internal structure of the electrolyte injection hole such that the electrolyte injection hole is sealed by the sealing member.