13544 1523015705

In Situ Investigation of the Dynamic Evolution of Materials and Interfaces in Energy Storage Systems

  • Date: Apr 19, 2018
  • Time: 15:30 - 16:30
  • Speaker: Prof. Matthew T. McDowell
  • Assistant Professor; Georgia Institute of Technology; G. W. Woodruff School of Mechanical Engineering; School of Materials Science and Engineering; Atlanta, Georgia, USA E-mail: mattmcdowell@gatech.edu
  • Location: Max-Planck-Institut für Eisenforschung GmbH, Seminar Room 1
  • Room: Seminar Room 1
  • Host: Max-Planck-Institut für Eisenforschung GmbH
  • Contact: rco@mpie.de
Abstract: In energy storage devices, materials evolve from their initial state due to electrochemical reactions and interfacial instabilities at interfaces. To develop batteries with improved safety, energy density, and lifetime, it is critical to understand transformation mechanisms and degradation processes within these devices. In my research group, multiscale in situ techniques are used to reveal reaction mechanisms and interfacial transformations to guide the development of better batteries and other devices. Our recent work has used in situ transmission electron microscopy (TEM) to reveal phase transformation pathways and mechanical degradation/fracture when sulfide nanocrystals react with different alkali ions (lithium, sodium, and potassium). Surprisingly, mechanical fracture was found to occur only during reaction with lithium, despite larger volume changes during reaction with sodium and potassium. Since fracture is a known capacity decay mechanism in batteries, this result indicates that these materials are useful for the development of novel, high-energy sodium and potassium batteries. In a different study, operando synchrotron X-ray diffraction methods were used to precisely measure crystallographic strain evolution in battery electrode materials; this technique enables measurements beyond what is possible with TEM. In the final portion of the presentation, in situ X-ray photoelectron spectroscopy (XPS) experiments that reveal chemical evolution of solid-state interfaces in energy storage and electronic materials will be presented. Overall, this research demonstrates how fundamental understanding of dynamic processes can be used to guide the design and engineering of new materials and devices with high energy density and long lifetime.

Biography: Matthew McDowell is an assistant professor at Georgia Tech with appointments in the School of Materials Science and Engineering and the G. W. Woodruff School of Mechanical Engineering. He received his Ph.D. from Stanford University in 2013. He is the director of a research group focused on understanding and controlling dynamic materials processes within electrochemical systems. McDowell has 56 publications, and he has received numerous awards, including the NSF CAREER Award, the AFOSR YIP Award, the ACS PRF Doctoral New Investigator Award, and a Scialog Fellowship. For more information, see http://mtmcdowell.gatech.edu.

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