The Department of Mechanical, Materials, and Aerospace Engineering presents a special seminar given by Carlo Segre, Duchossois Leadership Professor, professor of physics, deputy director of Materials Research Collaborative Access Team (MRCAT), director of Center for Synchrotron Radiation Research and Instrumentation (CSRRI), deputy Director of BioCAT, and professor of materials science and engineering at Illinois Tech. Segre will present “Tuning Li-ion Anode Performance with High Entropy Oxides,” on Wednesday, October 9, from 12:45–1:45 p.m. in room 104 of the Rettaliata Engineering Center.

Abstract:
High entropy oxides such as (MgCoNiCuZn)O have shown promising results as conversion anodes for Li-ion batteries with high gravimetric capacity and excellent cycle stability. This material and a number of derivatives are initially prepared in a rock salt structure which is immediately reduced to a heterogeneous mixture of metallic nanoparticles and metal oxides, some of which appear to be redox active. It is this heterogeneous mixture which appears to inhibit metallic nanoparticle growth, thereby slowing capacity fading with cycling. In order to better understand the role of each component and how composition affects the performance, we have successfully prepared the rock salt structure as a four-metal “medium” entropy oxide by removing each of the five metal components in turn, as well as a six-metal high entropy oxide by adding Fe. We have also studied the effect of the initial structure of a high entropy oxide on performance by comparing the (MgFeCoNiZn)O rock salt and the (TiFeCoNiZn)3O4 spinel materials.

One of the primary characterization tools is the use of synchrotron radiation to study the electronic and local structure of the metal atoms in these systems a various states of charge. Here we present ex situ and in situ x-ray absorption spectroscopy and x-ray pair distribution function measurements on these materials designed to probe the contributions of the individual metal components and overall structure to the electrochemical performance of these anode materials. Our results show that the electrochemical capacity is governed not only by the redox active species, but also by the capacity of the metallic nanoparticles to be reduced by additional Li-ions on the surface or formation of Li-metal alloys.

This research was supported in part by Illinois Institute of Technology’s Duchossois Leadership Program. MRCAT operations are supported by the Department of Energy and the MRCAT member institutions. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

Biography:
My research centers around the structure and electronic properties of complex materials including superconducting, magnetic, catalytic, and energy storage materials.

Experimental techniques used in my research include; material synthesis through arc-melting, powder metallurgy, and advanced chemical methods; structural characterization of the samples performed by x-ray powder diffraction and xray absorption fine structure; and measurement of electronic properties by resistivity, magnetic susceptibility, and x-ray absorption spectroscopy. Specific topics of interest include: structural and electrochemical properties of advanced battery materials; in-situ structural studies of catalytic materials for use in fuel cells; structural and electronic properties of magnetoelectric materials and other perovskite materials prepared in the form of nanoparticles and thin films; local structural studies of structural materials for use in nuclear reactors, including in-situ corrosion studies and characterization of nano-crystalline inclusions in steels; development of x-ray optics for synchrotron radiation experimentation.

I also am an active participant in Illinois Tech’s Center for Synchrotron Radiation Research and Instrumentation (CSRRI); serving as center director and as deputy director of the Materials Research Collaborative Access Team (MRCAT) which operates an experimental facility for materials research at the Advanced Photon Source (APS). I have been involved in the development of crystal optic devices for delivery and detection of x-rays at synchrotron beamlines.

Since 1992, I have been involved with the International Bridge Building Committee. We organize the Chicago Regional Bridge Building Contest each winter and the International Bridge Building Contest in odd years. This contest has grown, over the past 37 years, to be an integral part of many high school physical science curricula.