Secondary battery

A secondary battery comprising:

• an electrode assembly comprising:
• a first electrode;
• a separator;
• and
• a second electrode,
• wherein the first electrode, the separator, and the second electrode are alternately stacked;
• a case configured to accommodate the electrode assembly, the case comprising a long-side portion extending in a stacking direction of the electrode assembly and short-side portions connected to two opposite ends of the long-side portion, the short-sided portions having a smaller area than the long-side portion;
• a cap plate coupled to the case to seal the case;
• a terminal unit mounted on the cap plate and electrically connected to each of the first electrode and the second electrode;
• and
• an insulating member mounted between the electrode assembly and the case, the insulating member further mounted between the electrode assembly and the cap plate, the insulating member being formed of an insulating material,
• wherein the electrode assembly comprises two opposite end surfaces perpendicular to the stacking direction, and the two opposite end surfaces are adjacent to the short-side portions of the case.