Faculty Advisor: Sylwia Ptasinska, Department of Physics and Astronomy and Radiation Laboratory

Low-energy Electron Attachment to Ethylene Carbonate (Summer 2024)

The motivation of this project is to gain further insight into the dissociation dynamics of ethylene carbonate via a Dissociative electron attachment (DEA) study. DEA involves gas-phase collision between a molecule of interest and low-energy electrons (LEEs) in range of 0-20 eV to discern what anionic fragments are produced from the molecule. Ethylene carbonate is a common component of Lithium Ion Batteries (LIBs), as it is the only organic solvent that enables the solid-electrolyte interface (SEI) to be formed on the surface of graphitic carbon, which allows for the reversible reaction of graphite with lithium for hundreds of cycles. Previous studies have shown that LIBs (and specifically ethylene carbonate) degrade under the presence of ionizing radiation. Since secondary, low-energy electrons (0-20 eV) are the  most common intermediate product of ionizing radiation, a DEA study can further illuminate the possible dissociation and degradation processes that occur in the widely used LIBs. This study can be combined with our group's current work on a related carbonate, diethyl carbonate (DEC). These two together form a common pairing inside LIB anodes because of DEC's low viscosity facilitating ion transport and ethylene carbonate's high dielectric constant dissolving the salts.

Additionally, I plan on developing a broader toolbox for engaging in DEA studies by honing two techniques: VMI and thin film DEA. VMI stands for Velocity map Imaging, and allows for an additional spatial element to DEA studies by providing an angular distribution for each fragment. Such a study can illuminate the geometry of how these bonds break as well as the kinetic energy profiles of the anionic  fragments, which further improves the understanding of the energetics associated with the dissociation. Thin film DEA is a variation on the current gas-phase DEA. Though gas-phase DEA can uncover many of  the energetic aspects of a molecule, it has a natural shortcoming since a gas-phase molecule exists as an isolated system. However, thin film DEA allows for a clearer understanding of how a collective solid  mass of molecules behave under low-energy electron collision. Such a study is much more applicable to biological environments and to the standard LIB usage environment of ethylene carbonate.