Zebra batteries

Abstract

By using molten sodium chloroaluminate as secondary electrolyte, a series of solid transition metal chlorides can be used as positive electrodes in cells with sodium as the negative and beta-alumina as the solid electrlyte. Nickel chloride is preferred and Zebra batteries based on this cell reaction have been developed to the pilot-line production stage. The batteries have a number of features which make them attractive for electric-vehicle applications. Thus, the cells can be assebled in the discharged state eliminating the need to handle liquid sodium. By locating the positive electrode inside the beta-alumina tube, square cell cases can be used giving maximum packing efficiency in batteries. The absence of corrosion in the cell leads to a long life and high reliability. For electric-vehicle applications safety is very imporant, and crash testing has shown that even serious damage to the battery in a crash situation would not present a significant additional hazard to the driver or passengers. The remaining technical challenges are to increase the specific power of the battery towards the end of discharge and to demonstrate that the processes, which have been developed for cell and battery production, are capable of meeting the cost targets.