Ni_xCo_yO_z CATALYST FOR ORR AND OER FOR SODIUM AIR BATTERY

Sodium-air batteries recently have been being studied as an alternative for lithium oxygen 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 electrode reactions as lithium-air batteries. In order to solve this problem, a mechanism of O₂ reduction and evolution reactions (ORR and OER) must be understood, and an appropriate catalyst must be employed.

In this work, we studied ORR and OER in PEGDME500-based electrolytes, in the presence of Na⁺ ions, with and without catalyst application. For that purpose, two kinds of Ni_xCo_yO_z catalysts were synthesized by electoless method. The first one was synthesized on Black pearl particles, using Pt as an initiator of the synthesis, and the other one without using Black pearl and Pt. Glassy carbon electrode was coated by the catalysts, with loading of ~70µg/cm², and then tested in ORR and OER processes.

It was found that the both catalysts didn’t influence reduction potential, but increased reduction current. In addition, the both catalysts shifted oxidation potential towards more positive values, which indicates increased rate of chemical disproportionation of NaO₂ to Na₂O₂ in the presence of the catalysts.