Advanced Electrochemical Properties of PrBa0.5Sr0.5Co1.9Ni0.1O5+delta as a Bifunctional Catalyst for Rechargeable Zinc-Air Batteries

Various simple and layered perovskites have been extensively investigated as promising cathode materials for metal-air batteries and fuel cells, because of their tunable structural, electronic, and chemical properties. However, the electrocatalytic activity of perovskite oxides towards the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) must be improved by increasing the slow kinetics and by decreasing the overpotential associated with those reactions. Doping with other transition metals such as Ni, Mn, Fe and Cu represents one of the effective chemical methods to improve the catalytic activity of perovskite oxides. Herein, we investigate Ni-doped cobalt-based double perovskites, PrBa0.5Sr0.5Co2-xNixO5+delta (x=0, 0.1, 0.2 and 0.3), as promising cathode materials for rechargeable alkaline Zn-air batteries. PrBa0.5Sr0.5Co1.9Ni0.1O5+delta (PBSCN1) shows low Tafel slopes (OER: 83 mV dec(-1) and ORR: 67 mV dec(-1)), favorable onset potentials (OER: 1.513 V vs. RHE at 1 mA cm(-2) and ORR: 0.720 V vs. RHE at -1 mA cm(-2)), and high limiting currents (OER: 25.20 mA cm(-2) and ORR: -5.67 mA cm(-2)). In addition, it shows improved discharge-charge performances for a full-cell Zn-air battery. The enhanced electrochemical properties of PBSCN1 could be achieved by the high concentration of surface oxygen species, and the coexistence of different chemical states of cobalt cations caused by the presence of nickel cations in the lattice. Based on these results, PrBa0.5Sr0.5Co1.9Ni0.1O5+delta could be considered a promising cathode material for Zn-air battery systems.