Anna-Catharina came to the OESL with a degree in Biochemistry and Molecular Biology from Michigan Technological University.  She spent time this summer pinning down the degradation pathways of some of our redox shuttle compounds.

Fragmentation Analysis of Labeled Phenothiazines via Ion Trap Mass Spectrometry; Anna-Catharina Wilhelm and Thomas F. Guarr

The incorporation of organic compounds that display reversible electrochemical oxidation at very high potentials into lithium batteries has been shown to prevent dangerous overcharge conditions.  In order to better understand possible degradation pathways of such compounds (typically called “redox shuttles”), their breakdown was examined by mass spectrometry.  Previous studies of shuttle stability have been limited to empirical testing, modeling, or very limited analysis of reaction products.  In this project, ion trap mass spectrometry was used to explore the sequential fragmentation of several deuterium labeled compounds that are good candidates for such applications.  Using this approach, it was possible to selectively isolate and fragment both the oxidized (cation radical) and protonated forms of the parent compound.  Careful analysis of the data clearly shows that these two species break down by different mechanisms.  The results will aid in the design of more durable second-generation redox shuttles.

Anna-Catharina is beginning her PhD pursuit at the University of British Columbia this fall.  Best wishes for your future Anna!  Keep on running and enjoy our neighbor to the north.