Nora is a graduate of (the) Ohio State University. Yes, I know, but we still let her in the building. She is our third female Chemical Engineer intern this summer!
Characterization and degradation studies of redox-active organic heterocycles
Nora Shaheen, Nick Mortimer, Shane Mann, and Dr. Thomas Guarr
Protecting batteries from overcharging is critical to prolonging the battery lifetime and preventing dangerous thermal runaway events. Redox shuttles are electrolyte additives that reduce the risk of such events, and therefore help make batteries safer for use. While a myriad of redox shuttles exist, this study focuses predominantly on 9-methyl-3,6-di(t-butyl)carbazole, and 10-methyl-3,7-di(t-butyl)phenothiazine-5,5-dioxide. These heterocycles have shown to be efficient redox shuttles, but further studies into 1) solubility in the desired electrolyte, 2) mass transfer characteristics and limitations, and 3) stability under normal use conditions are necessary. Rotating Disk Electrode (RDE) was used to study the diffusion coefficients of phenothiazine-5,5-dioxides with various N-substituents. Ion Trap Mass Spectrometry (MS) was used to study the gas-phase fragmentation patterns of deuterium-labeled derivatives of these compounds. Lastly, the chemical stability of oxidized 10-methyl-3,7-di(t-butyl)phenothiazine-5,5-dioxide was examined using UV-Vis. The compound was oxidized using bulk electrolysis and through chemical oxidation; preliminary data indicates there are minimal changes in the optical spectrum over time. Further studies are necessary to determine the long-term stability of the oxidized material.
Nora is attending Chemical Engineering graduate school at Case Western Reserve University this fall. We wish her the best and we know she will be amazing.