A-Site Engineered Double Perovskite Oxide as Air Electrode for Rechargeable Zn-Air Batteries

Date

2023-9

Author

Erdil, Tuncay

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Electrochemical energy storage and conversion devices, such as rechargeable metal-air batteries, water electrolyzers, and fuel cells, heavily rely on the electrochemical oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The OER, characterized by slow reaction kinetics, poses challenges to the efficiency of these devices. Perovskite oxides have emerged as promising OER electrocatalysts due to their versatile physicochemical properties and high intrinsic activities. However, concerns persist regarding their structural stability and long-term electrochemical performance. Consequently, there is a pressing need for a highly active and structurally stable perovskite oxide electrocatalyst to enhance the overall performance of electrochemical energy storage devices, particularly zinc-air batteries. In this work A-site management strategy is applied to tune the activity and stability of the double perovskite oxide. A range of double perovskite oxides was synthesized from La2CoMnO6 (LCM) up to Ba2CoMnO6 (BCM) by substituting Ba+2 with La+3 to understand the origin of OER performance by investigating crystal structure, electronic structure, Fermi level, and work function. The crystal structure transitions from cubic to 2H hexagonal, while simultaneously observing a decrease in the work function with increasing levels of Ba incorporation. It suggests a relationship between crystal structure-oxygen vacancy-work function and activity for BaxLa2-xCoMnO6 (x = 0, 0.5, 1, 1.5, 2) double perovskite oxide electrocatalysts. The double perovskite oxide 2H-Ba2CoMnO6 demonstrates exceptional electrochemical performance and stands out as the most promising candidate for zinc-air battery applications. Notably, it displays a remarkable OER activity, characterized by a mere 288 mV overpotential at a current density of 10 mA cm⁻². Moreover, this material exhibits an extended period of stability, all the while maintaining its structural integrity without succumbing to instability concerns. This novel variety of double perovskite oxide not only showcases remarkable performance in terms of OER and battery applications, but it also serves as an elucidating model for comprehending the impact of crystal structure and work function on OER performance.

Subject Keywords

Oxygen Evolution Reaction, Perovskite Oxide, Electrocatalyst, Zinc-Air Battery

URI

https://hdl.handle.net/11511/105448

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Graduate School of Natural and Applied Sciences, Thesis