1. Field
Embodiments relate to a secondary battery and a secondary battery module.
2. Description of the Related Art
Secondary batteries are rechargeable batteries, and may be broadly used in portable electronic devices, e.g., cellular phones, notebook computers, and camcorders.
A secondary battery is formed by inserting an electrode assembly, in which a positive electrode, a negative electrode, and a separator are wound in the form of a jelly roll, into a case through an opening of the case, and covering the opening by using a cap assembly. Current collecting plates are formed at two ends of the electrode assembly and are electrically connected to a terminal unit of the cap assembly. Accordingly, if an external terminal is connected to the terminal unit, current generated in the electrode assembly may be provided to the external terminal via the current collecting plates and the terminal unit.
The terminal unit may include a positive electrode rivet and a negative electrode rivet connected to the current collecting plates, and rivet terminals bonded to the positive and negative electrode rivets in order to be connected to bus bars. Bonding between the positive electrode rivet or the negative electrode rivet and a rivet terminal, and between a rivet terminal and a bus bar may be performed by using a laser welding method. However, since the positive and negative electrode rivets are generally formed of dissimilar metals, if the rivet terminals are formed by using one metal, dissimilar metal welding may be performed between the positive electrode rivet or the negative electrode rivet and a rivet terminal.