Lithium ion battery

A lithium ion battery (100) includes a cell assembly (20), a casing (200) containing the cell assembly with electrolyte filling therein, a cap assembly (300) a retaining member (50) and an insulator (70). The cell assembly comprises a number of stacked electrode plates, each electrode plate having an electrode ear. The cap assembly includes a cap plate (30) covering a top side of the casing, a pair of electrode terminals (10) assembled to one side face of the cap plate, and a pair of cap ears (41, 42) connecting to and electrically separated from the other side face of the cap plate. The retaining member is connecting the cap plate, the pair of electrode terminals and the cap ears, and the insulator electrically separates the electrode terminals from the cap plate and the cap plate from the cap ears.