Abstract: A method of joining thermoplastic frames of a bipolar battery to form a leak-free battery stack. The battery includes a stack of generally rectangular thermoplastic frames, including a series of central frames and a pair of end frames. Each central frame has an opening and a bipolar plate, consisting of a positive electrode and a negative electrode, separated by an electrically conductive substrate, is mounted across the opening. The opposed surfaces of the frame project outwardly beyond the bipolar plate. To join the frames together, a pair of frames is mounted in spaced relation and a pair of back-to-back focused infrared heaters are positioned in the space between the frames and the focal point of each heater is directed into registry with the surface of the respective frame to melt or fuse the surface. The heating unit is then withdrawn and the frames are moved into contact with each other to weld the fused surfaces together.

Abstract: A light weight deflection-resistant end block is provided for a battery and comprises a base member of a light weight, chemically inert and electrically resistive material which has one or more cavities adapted to receive low density, substantially rigid inserts such as honey-combed aluminum.