Lithium-oxygen batteries potentially could have energy storage capacities that rival gasoline fuel, but there remains much fundamental scientific knowledge to learn about these batteries before the technology can be commercialized. In particular, some of the chemical products formed during the operation of the batteries can slowly degrade and poison the materials, leading to performance losses over extended periods of operation. This research project seeks to overcome these problems by exploring a class of inexpensive, mixed metal oxide electrocatalysts that may alter the chemistry of lithium-oxygen batteries. This project aims to develop a framework to engineer the chemistry of lithium-oxygen batteries, which are a potential next-generation energy storage device, and to improve their performance. The studies combine advanced characterization methods and theoretical calculations to determine how the properties of the oxide surfaces influence the products that are produced on lithium-oxygen electrodes. These insights will be leveraged to develop design principles that will aide in identifying oxide electrocatalysts that improve battery cell performance. The researchers involved in this project will partner with local K-12 schools to involve economically disadvantaged students with the proposed research through summer internships and student exchanges. They aim to inspire the students to pursue careers in science and engineering.
A fundamental understanding of the reactions occurring at solid-solid interfaces is critical for the development of next-generation energy storage devices, such as lithium-oxygen batteries. Lithium-oxygen batteries have attracted significant interest in recent years due to their exceptionally high theoretical energy density. If even 15% of this energy density is achieved, then it would equal the value of gasoline, making lithium-oxygen batteries with driving ranges of up to 500 miles per charge commercially viable. While this technology is very attractive, numerous technical challenges need to be overcome before its widespread adoption is possible. Some of these challenges include: (i) insolubility of the solid discharge reaction products, leading to clogging of the cathode and eventually resulting battery cell death; (ii) low roundtrip (discharge-charge cycle) efficiency due to high charge overpotentials to dissociate the main discharge reaction product, lithium peroxide; and (iii) instability of electrolytes at high overpotentials. This research project seeks to alleviate these issues by designing solid-solid interfaces at the cathode of lithium-oxygen batteries that selectively stabilize lithium-deficient discharge products that are not insulating and can be dissociated at reasonable overpotentials. The researchers will apply a combined experimental and theoretical approach to study the chemistry at these solid-solid interfaces with the aim of designing materials that can selectivity tune the discharge product distribution such that it leads to improved battery performance. In particular, the work will involve a combination of advanced characterization studies and theoretical calculations to determine how the elemental composition, electronic properties, and symmetry of the oxide surface influence the discharge product distribution in lithium-oxygen cathodes. The studies will elucidate the effect of the global oxide crystal structure on the discharge product formation and lead to the development of design principles for identifying oxide electrocatalysts that are highly selective towards the formation of lithium-deficient oxide discharge products and therefore exhibit low charge overpotentials.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
