Synthesis and utilization of the perovskite as energy materials

Abstract

With technological advancement, population growth, and economic development, the demand for high-efficiency memory and energy-generating devices has increased significantly. In particular, eco-friendly energy generators and large-capacity data storage devices are a big challenge due to global warming and the growth of artificial intelligence (AI) and the Internet of Things (IoT). As a sustainable electrochemical device, metal-air batteries (MABs) are of significant interest because of their extremely high specific energy density, commercially feasible efficiency, and environmentally friendly properties. To increase the efficiency of MAB, a noble metal-based catalyst is used to enhance electrochemical activity. However, there are still problems with commercialization due to a lack of resources and stability. To solve these problems, noble metal-free perovskite oxide-based catalysts are being actively studied, paying attention to high oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities. In addition to catalytic activity, perovskites are attracting attention for their magnetic properties that can be applied to spintronics and memory devices. Depending on the B-site doping element, perovskite exhibits various properties and flexibility, such as ferromagnetic, ferromagnetic, antiferromagnetic, multiferroic, along with metallic, and insulating properties. Among them, double perovskites containing 3d-5d transition metals are promising candidates for ferromagnetic insulators, which are difficult to find in nature, due to their unique ferromagnetic mechanism. This dissertation focuses on modifying the properties of perovskite by various synthetic methods to enhance the catalytic activity of energy storage devices or to explore novel magnetic properties. In particular, I have study the perovskite doping effect of heteroatoms, the enhancement of physical properties through strain transformation, the determinants of ORR and OER activity, and the effects of crystal structures on electronic and magnetic properties. I started with the basic principles of MAB, oxygen reduction/evolution, reaction, and ferromagnetism in chapter 1. And then, I introduce my research studying perovskite catalysts and ferromagnetic semiconducting thin-film as follows : Chapter 2. Advanced electrochemical properties of PrBa0.5Sr0.5Co1.9Ni0.1O5+δ as a bifunctional catalyst for rechargeable zinc-air batteries. Chapter 3. Effect of Zn addition on electrochemical performance of Al-air battery. Chapter 4, Enhancing bifunctional electrocatalytic Activities via Metal d-band-center-lift induced by oxygen vacancy at sub-surface of perovskites. Chapter 5. Monolithic heteronanomat paper air cathodes toward origami-foldable/rechargeable Zn–air batteries. Chapter 6. Co3O4 exsolved defective layered perovskite oxide for energy storage systems. Chapter 7. Ferromagnetic semiconductor with perpendicular magnetic anisotropy by strain.