GRAPHITE AND METAL OXIDE CATALYST SUPPORTS FOR RECHARGEABLE OXYGEN ELECTRODES

METAL-AIR BATTERIES, NOTABLY ZINC-AIR AND IRON-AIR, ARE ATTRACTIVE CANDIDATES FOR ELECTRIC VEHICLE PROPULSION BECAUSE OF THEIR HIGH SPECIFIC ENERGY AND INHERENT SAFETY. THESE BATTERIES REQUIRE A RECHARGEABLE, OR BIFUNCTIONAL, OXYGEN ELECTRODE THAT GENERATES OXYGEN DURING CHARGE AND REDUCES IT DURING DISCHARGE. PHASE I OF THIS PROJECT SEEKS TO DEVELOP A STABLE CATALYST SUPPORT USING A THREE-PRONGED APPROACH. FIRST, THREE ALTERNATIVE CATALYST SUPPORTS ARE BEING DEVELOPED: (1) GRAPHITIZED CARBON (N774, SHAWINIGAN BLACK, AND CARBON 60, THE FIRST TWO OF WHICH HAVE SHOWN DRAMATICALLY IMPROVED STABILITY); (2) MANGANESE DIOXIDE, WHICH IS AN EXCELLENT CATALYST FOR OXYGEN REDUCTION; AND (3) LANTHANUM NICKELATE, WHICH ALSO SHOWS PROMISE AS BOTH A CATALYST AND A SUBSTRATE. SECOND, IMPROVED CATALYSTS FOR THE SUBSTRATES, WHICH LOWER THE OVERPOTENTIAL FOR OXYGEN EVOLUTION ARE BEING DEVELOPED, SPECIFICALLY COBALT TETRAMETHOXY PHENYL PORPHYRIN, MANGANESE DIOXIDE, NICKEL-COBALT SPINEL, AND A VERY PROMISING PEROVSKITE. THIRD, THE EFFECTS OF TEMPERATURE, CURRENT DENSITY, AND ELECTROLYTE CONCENTRATION ON LIFETIME ARE BEING QUANTIFIED TO COMPARE REAL-TIME ELECTRODE LIFETIMES UNDER NORMAL STRESSWITH THOSE UNDER ACCELERATED STRESS CONDITIONS.