Rechargeable battery and pack of the same

A rechargeable battery pack comprising:

• a plurality of unit cells, each one of the unit cells having an electrode assembly with a first electrode electrically connected to a case, the case having an opening in a plane parallel to a flat side surface of the electrode assembly, and a second electrode electrically connected to an electrode terminal, the electrode terminal extending away from the case and insulated from the case;
• and
• a bus bar connected between the electrode terminal of a first unit cell of the unit cells and the case of a second unit cell of the unit cells with the electrode terminal of the first unit cell having a height that is different from a height of the case of the second unit cell, wherein the bus bar includes a first raised portion and a second portion bent away from the first raised portion, wherein the first raised portion is connected to the electrode terminal of the first unit cell, and the second portion is directly connected to a wall of the case of the second unit cell,
• wherein the wall protrudes inward towards an interior of the second unit cell and generates a bus bar connection recess on an exterior of the wall, wherein the second portion of the bus bar is connected to the bus bar connection recess.