A secondary battery comprising: an electrode assembly comprising a first electrode plate, a second electrode plate; a can arranged to house the electrode assembly and comprising an opening at one end of the can; a cap assembly comprising a cap plate, an insulating plate, and a terminal plate, wherein: the cap plate being arranged to seal the opening of the can, the cap plate comprising a first terminal through hole; the insulating plate is disposed on a surface of the cap plate facing towards the electrode assembly and comprises a second terminal through hole; and the terminal plate is disposed on a surface of the insulating plate facing towards the electrode assembly and comprises a third terminal through hole and a protrusion formed adjacent the third terminal through hole, wherein the protrusion is formed on the terminal plate on a surface facing towards the electrode assembly; the secondary battery further comprising: an electrode pin comprising a portion disposed on a surface of the cap plate facing away from the electrode assembly and a portion inserted into the first, second and third terminal through holes, wherein a portion of the electrode pin interlocks with the protrusion of the terminal plate. an electrode assembly comprising a first electrode plate, a second electrode plate; a can arranged to house the electrode assembly and comprising an opening at one end of the can; a cap assembly comprising a cap plate, an insulating plate, and a terminal plate, wherein: the cap plate being arranged to seal the opening of the can, the cap plate comprising a first terminal through hole; the insulating plate is disposed on a surface of the cap plate facing towards the electrode assembly and comprises a second terminal through hole; and the terminal plate is disposed on a surface of the insulating plate facing towards the electrode assembly and comprises a third terminal through hole and a protrusion formed adjacent the third terminal through hole, wherein the protrusion is formed on the terminal plate on a surface facing towards the electrode assembly; the secondary battery further comprising: an electrode pin comprising a portion disposed on a surface of the cap plate facing away from the electrode assembly and a portion inserted into the first, second and third terminal through holes, wherein a portion of the electrode pin interlocks with the protrusion of the terminal plate. the cap plate being arranged to seal the opening of the can, the cap plate comprising a first terminal through hole; the insulating plate is disposed on a surface of the cap plate facing towards the electrode assembly and comprises a second terminal through hole; and the terminal plate is disposed on a surface of the insulating plate facing towards the electrode assembly and comprises a third terminal through hole and a protrusion formed adjacent the third terminal through hole, wherein the protrusion is formed on the terminal plate on a surface facing towards the electrode assembly; the secondary battery further comprising: an electrode pin comprising a portion disposed on a surface of the cap plate facing away from the electrode assembly and a portion inserted into the first, second and third terminal through holes, wherein a portion of the electrode pin interlocks with the protrusion of the terminal plate.