Comparative Characterization of Catalytic Properties of Ta, Nb, Ni_xCo_yO_z and Carbon in Sodium-Air Batteries

Sodium-air batteries have been recently studied as an alternative for lithium-air ones. In spite of lower theoretical specific energy (1980Wh kg^-1 of sodium vs. 3600Wh kg^-1 of lithium), abundance of sodium provides an advantage for its usage as a metal anode over lithium. Sodium-air batteries have similar reversibility problem of cathode reactions as lithium-air batteries. Applying an appropriate material as a cathode catalyst and/or supporting substrate can contribute to the formation of more reversible products on charge, increasing the cyclability and reducing ORR and OER overpotentials of the battery.

In this work, we studied ORR and OER in sodium-PEGDME500-based electrolytes, testing Ta, Nb, Ni_xCo_yO_z, and Black pearls powders as the catalysts. For this purpose, the three-electrode half-cell with neat or coated-by-catalyst glassy carbon working electrode were assembled. The catalysts loading of about 40 µg/cm² was used.

It was found that in sodium PEGDME500-based electrolytes carbon materials have the highest catalytic activity for ORR and OER.