Highly Durable Bifunctional LaCo_<i>x</i>Ni_1–<i>x</i>O₃-Based Electrocatalysts for Zinc–Air Batteries

Oxygen reduction and evolution are the most popular reactions in energy conversion and storage systems, such as fuel cells, water electrolyzers, and metal–air batteries. Intensive research is focused on designing efficient bifunctional electrocatalysts to decrease the substantial overpotential associated with these reactions. The perovskite-based bifunctional electrocatalysts were synthesized from the partial replacement of the B-site metal of LaCoO3 with nickel on N-doped carbon, using ball milling and pyrolysis methods. The synthesized material exhibits the highest activity toward oxygen reduction (jk = 25.1 A g–1 at 0.8 V) and evolution reactions (jk = 33.9 A g–1 at 1.55 V). The bifunctional activity was evaluated using the ΔE value, which is 0.71 V by the conventional method, and it is 0.68 V at which the mass-specific kinetic current reaches 10 A g–1 for both OER and ORR. The liquid electrolyte rechargeable zinc-air battery shows promising power density (106.3 mW cm–2) and very high stability for 740 h of operation, which is the highest among all the perovskite-based electrocatalysts. The highest stability originates from the perfect synergy between the carbon substrate and metal oxides, which is achieved by the ball milling process before pyrolysis. This study demonstrates the possibility of generating ultrastable electrocatalysts from perovskite-based materials.