Secondary battery

A secondary battery comprising:

• an electrode assembly comprising a first electrode plate having a first electrode tab, a second electrode plate having a second electrode tab and a separator between the first electrode plate and the second electrode plate;
• a case comprising a body accommodating the electrode assembly, a cap plate covering a top portion of the body, and a bottom plate covering a bottom portion of the body;
• a first electrode terminal electrically connected to the first electrode tab at the top portion of the body;
• a second electrode terminal adjacent the first electrode terminal at the top portion of the body and electrically connected to the second electrode tab through the case;
• and
• a connection plate electrically connected to an end of the second electrode tab at the bottom portion of the body, the connection plate being configured to bend away from the bottom plate and to bend toward the bottom plate with the end of the second electrode tab, the connection plate being on the bottom plate,
• wherein a coupling groove is on an outer surface of the bottom plate and a portion of a bottom surface of the coupling groove constitutes the connection plate, and
• wherein the bottom plate further comprises a cover plate placed in the coupling groove and fastened with the coupling groove to seal the connection plate.