The Li-air (O2) battery is a promising next-generation energy storage device with high energy density that is superior to any conventional electrochemical power source. Practical applications of such batteries are hindered by several challenges, e.g., low efficiency of catalysts, safety issues related to flammability of organic fluid electrolytes, and durability. Replacing the flammable organic fluid electrolytes currently used in the batteries with highly Li+ conductive, fire-resistant, and robust inorganic solid-state electrolytes is a critical milestone to address these issues. The successful incorporation of solid-state electrolytes into battery technologies requires an understanding of the associated Li+-O2 electrochemical reactions, i.e., the oxygen reduction reaction (ORR) and evolution reaction (OER) in solid-state air cathodes. The proposed plan will develop a novel nano-structured, carbon-metal nanoparticle composite for a lithium-oxygen battery with a solid state electrolyte that will improve the performance and safety of Li-air batteries, as well as contribute to the understanding of other related battery systems.
The project will focus on studying solid-state O2 electrocatalysis in a porous air cathode consisting of a new Li3OCl electrolyte and a nitrogen-doped nanocarbon ORR/OER bifunctional catalyst. The following tasks will be performed: (1) engineering of porous structures with well-defined three-phase interfaces (electrolyte, catalyst, and O2) in air cathodes, (2) elucidation of temperature-dependent O2 diffusion and Li+ transport mechanisms along with electrochemical reaction kinetics in solid-state cathodes via synergistic modeling and experimental characterization efforts, and (3) design of 3D nanoporous air cathode architectures that provide efficient mass and charge transports along with sufficient activity and stability for high-temperature Li-O2 electrochemical reactions. In addition to training graduate students, the PIs also plan to engage undergraduates and high-school students in research.