The research and development of a durable, elec. rechargeable Zn/O2 battery in the PSI-BEW project at the Paul Scherrer Institute is described in a review with many refs. The first phase included the development of La0.6Ca0.4CoO3-activated bifunctional O2 diffusion electrodes and zinc paste electrodes. The second phase included the optimization of the zinc paste electrode to improve the available capacity and peak power of the battery system. Based on the mass of the cell components, a specific peak power of 275 W/kg with O2 and 200 W/kg with air was calcd. for complete batteries. In collaboration with the Federal Institute of Technol., Lausanne, Switzerland, a bipolar filter-press type elec. rechargeable Zn/O2 battery delivering a peak power of ca. 100 W has been developed. The current-potential behavior was detd. as a function of the no. of bipolar cells (max. of 7), and the max. discharge capacity was detd. at different discharge rates. [on SciFinder (R)]