Our research projects use organic chemistry, polymer chemistry, and spectroscopy to solve problems in materials science and engineering. Currently we endeavor to utilize information on the basic structure and electronic properties of conjugated organic molecules in systems that have relevance to applications in lithium ion (Li-ion) batteries. Our group uses information to assist in the design of new materials for critical applications. We study the effect of electrolyte additives on battery performance, study new electrode materials for Li-ion batteries, and analyze the stability and reactivity of aromatic radical cations. Members of the Odom group will have opportunities to synthesize organic compounds, perform spectroscopic and electrochemical experiments, and incorporate materials Li-ion batteries.

Building Better Batteries: Safer, Longer-Lasting Li-Ion Batteries

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Despite their prevalence in consumer electronics, which ranges from cell phones to laptops to electric vehicles, secondary Li-ion batteries need improvement in order to extend their lifetimes. Each time a Li-ion battery charges and discharges, the liquid electrolyte (often carbonate solvents with lithium salts) partially decomposes, contributing to the formation of a solid electrolyte interface (SEI) layer between the electrodes and electrolyte. The cause for decomposition is that the electrolyte solvents are unstable in the voltages of lithium ion battery operation, which are generally quite reducing. We are developing additives for protection during normal cycling and during battery overcharge, when the electrical potential one or more batteries in a series is raised beyond the end-of-charge potential of the cathode. Operating in this overcharge results in electrolyte oxidation and increased temperatures, which can lead battery failure.

In addition to the decrease in battery lifetime, this failure mechanism can be dangerous if batteries ignite, causing a cascade of thermal runaway events in neighboring batteries. Given the size of the batteries in electric and hybrid electric vehicles (about 200 kg), thermal runaway is a major safety concern due to the large amount of reactive material within one battery pack. We are therefore improving the stability and efficacy of electrolyte additives through structural modifications for steric protection of reactive groups and electronic modification through the introduction of electron donating or withdrawing substituents. Involvement in this project can range from the synthesis of new small molecules as electrolyte additives, battery fabrication, and characterization of battery cycling performance and additive reactivity.

In addition to increasing battery lifetimes and preventing failure, ultimately some batteries will fail, whether silently or violently. It is the violent failure mechanisms we need to prevent, both for cost and safety reasons. We are therefore working on the development of small molecule additives for shutdown of Li-ion mobility, either in response to increases in temperature or battery potentials that are beyond a certain threshold. We are also interested in developing new separators – the microporous layer (often polymeric) between battery electrodes that keeps a battery from short circuiting – that would allow for temporary or permanent Li-ion battery shutdown when a battery is compromised.

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examples of cores we use for the synthesis of new redox shuttles

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glove box for battery assembly one of our coin cell battery cyclers

Our research is funded by the University of Kentucky’s Office of the Vice President for Research and the College of Arts and Sciences, the American Chemical Society Petroleum Research Fund under a Doctoral New Investigator award, the National Science Foundation Division of Chemistry (CSDM-B) and the Department of Energy Development and Independence of Kentucky.

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