Priya Moni

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Faculty Mentor: Yet-Ming Chiang

Direct Supervisor: William H. Woodford

Home University: University of Michigan

Major: Materials Science and Engineering

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Biography

I’m a senior studying Materials Science and Engineering at the University of Michigan. While I love all aspects of my field, I am particularly interested in materials for electronic device fabrication.  After completing my bachelors, I hope to obtain a Ph.D. in materials science and engineering and eventually become the principal investigator of my own lab.    In my free time I love playing the piano, doing graphic design, and playing with my baby cousin.

Abstract

Synthesis and characterization of Fe-doped high-voltage spinels for Li-ion battery cathodes

Electrochemical shock is the mechanical degradation of electrochemically active materials; in lithium-ion batteries, this can produce an increased cell impedance which may limits their useful lifetime. Micromechanical models have shown that electrochemical shock can occur by several different mechanisms, with different sensitivity to cycling rate and particle size, depending on the microstructure and phase behavior of the active material. Experimental studies of purely rate-dependent electrochemical shock are hampered by the complex phase behavior of most lithium storage compounds. Recent reports from Aruguman Manthiram’s group (UT-Austin) have suggested that Fe-doped high voltage nickel manganese spinel forms a continuous solid solution with respect to Li-concentration. To assess the utility of this material as a model system, lithium nickel manganese oxide (LiNi0.5Mn1.5O4) was doped with iron at various concentrations to produce materials that show a single phase throughout the entire electrochemical cycle.  Four iron compositions were synthesized by both solid state and solution co-precipitation routes.  The morphology and composition of the resulting compounds were studied using scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). X-Ray Diffraction (XRD) analysis was used to compare the lattice parameters of the fully lithiated sample to a 25% lithiated sample. Finally, electrochemical cycling experiments were performed to study each material’s electrochemical behavior.