Bi-functional air electrodes for metal-air batteries. Final report, September 15, 1993--December 14, 1994

摘要

The program was directed to the need for development of bifunctional air electrodes for Zn-Air batteries for the consumer market. The Zn-Air system, widely used as a primary cell for hearing-aid batteries and as a remote-site power source in industrial applications, has the advantage of high energy density, since it consumes oxygen from the ambient air utilizing a thin, efficient fuel-cell-type gas-diffusion electrode, and is comparatively low in cost. The disadvantages of the current technology are a relatively low rate capability, and the lack of simple reversibility. (open quotes)Secondary(close quotes) Zn-Air cells require a third electrode for oxygen evolution or mechanical replacement of the Zinc anodes; thus the development of a bifunctional air electrode (i.e., an electrode that can alternately consume and evolve oxygen) would be a significant advance in Zn-Air cell technology. Evaluations of two carbon-free non-noble metal perovskite-type catalyst systems, La(sub 1-x)CA(sub x)CoO(sub 3) as bifunctional catalysts for potential application in Zn-air batteries were carried out. The technical objectives were to develop higher-surface-area materials and to fabricate reversible electrodes by modifying the hydrophobic/hydrophilic balance of the catalyst-binder structures.