Secondary battery

A secondary battery comprising;

• a battery unit having a rectangular prism shape with two surfaces on opposite sides to one another and four sides each connected to the two surfaces with either one of the two surfaces being wider than any of the four sides of the battery unit, comprising a battery cell and a lead tab that protrudes from the battery cell;
• a frame case portion having, a flat plate shaped main body for supporting one of the two surfaces of the battery unit, said main body being wider and longer than said one of the two surfaces of the battery unit, comprising a first support portion extending on opposite sides of the main body at approximately 90 degrees for supporting the battery cell and a second support portion extending longitudinally from and directly connecter to the first support portion on the opposite sides of the main body for supporting the lead tab, said first support portion having a length approximately equal to a length of the main body;
• and
• a connection member for perforating a connection hole formed in the lead tab and extending in a direction of the second support portion;
• a terminal member having a generally rectangular prism shape with four sides and two surfaces in which one side of the lead tab is in direct physical contact with one of said two surfaces of the terminal member, said terminal member is interposed between the lead tab and the second support portion and is fixed on the second support portion, and said terminal member has a width greater than a width of the lead tab and a length equal to a length of the lead tab;
• a holder case having a generally rectangular prism shape with four sides and two surfaces in which a side of the lead tab opposite to that where the terminal member is disposed is in direct physical contact with the case holder, and said holder case has a width and length greater than a width and length of the lead tab,
• wherein the connection hole of the lead tab comprises:
• first connection hole that is spaced apart from a first edge of the lead tab by a first width, said first width w1 and a thickness t of the lead tab satisfies the equation w1×t≧3 mm2 and said first width w1 and a height h of the lead tab satisfies the equation w1×h≧310 mm2;
• and
• a second connection hole that is spaced apart from a second edge of the lead tab by a second width, said second width with respect to the overall width of the lead tab is in a ratio of 1:8 or less.