Bifunctional, Carbon-Free and Co3O4 Modified Silver and Nickel Electrodes for Lithium Air Battery

Kurzfassung

The operation of a secondary Li-air battery requires to run the battery in oxygen reduction reaction (ORR) as well as in oxygen evolution reaction (OER). OER represents the charge reaction and requires a sufficient catalyst for oxygen evolution. Currently carbon materials are widely used in cathodes of aqueous alkaline Li-air batteries due to their high electronic conductivity, stability, relatively low costs and catalytic activity towards oxygen reduction reaction (ORR) [1,2]. However, carbon-based cathode materials are non-stable in the potential range of OER as they start to corrode at potentials higher than open circuit voltage (OCV) [3,4]. Corrosion leads to high degradation corresponding to successive capacity loss and ultimately destruction of the cathode. To improve long-term stability and reduce side reactions such as H2 and CO2 evolution carbon-free bifunctional cathodes for aqueous alkaline Li-air batteries are requested [5,6]. In this poster we present cathodes with a combination of Ag, Ni or Ti4O7 and Co3O4. Cathodes were prepared with a dry-processed and solvent-free preparation method [7]. Electrocatalytic activity regarding both ORR and OER was investigated by cyclic voltammetry (CV) for up to 300 cycles in half-cells. Cathodes with the combination of Ag and Co3O4 show high activity for both reactions ORR and OER and a significant improvement in performance (high current densities) compared to both pure Ag and pure Co3O4 cathodes. Long-term tests show superior stability of the bimetal cathodes [6]. Furthermore the effects of different milling parameters have been investigated. In this presentation electrodes made out of different amount of Silver powder and Nickel powder have been produced and evaluated. Higher current densities could be achieved during discharge if the powder mixture is milled for one hour.