ZnMn2O4/Carbon Composite Recycled from Spent Zinc-Carbon Batteries for Zn-Air Battery Applications

Abstract

ZnMn2O4, a non-precious metal catalyst for oxygen reduction reaction (ORR), was recycled from the spent primary Zn–C battery and utilized in the zinc-air battery. Catalysts exhibiting facile ORR kinetics is a requirement for building efficient Zinc-air battery. ZnMn2O4 demonstrated an excellent catalytic activity towards ORR in an aqueous alkaline medium, with an onset potential of 0. 90 V vs RHE. The recycled ZnMn2O4 manifested a similar performance (at ∼1.0 V) as the chemically synthesized one with a specific capacity of 210 mAh gzn −1 at a constant current discharge of 15 mA cm−2. A single electrode potential study was done to comprehend the losses at the electrodes and to identify the limiting electrode. Interestingly, the cathode was improving during discharge, which is in contrast to the expectation due to the accumulation of peroxide around the catalytic layer. Although the anode has exhibited minimal polarization, beyond a capacity of 210 mAh g−1, the supersaturation of electrolyte occurs with zincate ion causing precipitation of ZnO on the cell components, thereby leading to sudden polarization of the cell and hence zinc electrode act as a limiting electrode in this system.