Enhancing the Performance of Air Electrode Structures Utilized in Aqueous Alkaline Flow Systems

The air electrode, responsible for converting air, the most abundant fuel on Earth, into vast amounts of power, remains one of the most fascinating and valuable technologies in the sustainable energy community. The value of this electrode is primarily due to its ability to produce substantial amounts of clean energy via electrochemical reactions that convert oxygen to electricity, heat, and water. It also has the potential to have long-term environmental impacts, such as the reduction of greenhouse gas emissions and increasing the utilization of renewable energy sources. The devices these electrodes are implemented in can supply the power generation needs of various systems, such as portable electronics, electric vehicles (EVs), and grid-scale energy storage. However, the stability and durability of the air electrode remains an issue due to the sluggish reaction kinetics, pore site obstruction, and catalyst active site degradation that occurs over time associated with the oxygen reduction reaction (ORR). Due to increased energy output demands and active material loading constraints defined by the Department of Energy (DOE), finding ways to maximize performance and durability can be complicated in harsh system environments with strict spatial limitations and high efficiency needs. These restrictions have forced researchers worldwide to think creatively and investigate various methods to increase the performance of the air electrode. This aspect led to the exploration of air electrodes and their structures through unique pathways, such as multifunctional microporous layer (MPL) investigations, manganese dioxide (MnO₂) catalyst modifications, and explorations of implementing these materials into aqueous alkaline flow systems. In this thesis, we discuss novel ideas and experimentation processes that led to the enhancements of air electrode structures used in electrochemical devices.