An improved electrical connector system for joining an electrode and a terminal in an electrochemical cell is provided in which physical force is used to maintain the electrical contact. An extension member provided on the electrode is adapted to fit within a key-hole shaped opening provided in the terminal. A core member provided within the extension member is formed of a material having a higher thermal expansion than either the extension member or the terminal. Upon heating, the core member expands greater than both the terminal and the extension member, thereby physically forcing the extension member into electrical contact with the terminal.
