Inamori Fellowship Award Winner 2014-15
Mr. Andrew Ulvestad - Inamori Fellow 2015
The 2015 Inamori Fellowship is awarded to Andrew Ulvestad, who is a Physics PhD student working in Oleg Shpyrko's group.
As part of his PhD thesis work, Andrew has developed a unique "Lensless X-ray nanoscope", which allows internal nanoscale imaging of complex materials and devices, under operating conditions or in complex enviroments. This is currently extremely challenging or downright impossible to do with most other experimental techniques.
These new x-ray imaging probes can help unravel the complexity of nanoscale disorder - in Andrew's case, formation and dynamics of atomic-scale defects, so-called dislocations, that are commonly associated with performance degradation, but which can also potentially be used to control or optimize the desired materials properties.
The key idea used by Andrew is to direct bright beams of x-rays through battery enclosure, through a thick layer of electrolyte and past the complex electrode structure. By taking advantage of high penetrating power of x-rays, Andrew was able to zoom in on a single microscopic crystalline grain of a Li-ion material and observe complex dynamics that occurs during battery operation.
These new and unique imaging methods developed by Andrew, are based on solving a famous "phase problem", where only the intensities (amplitudes) of Fourier transform functions can be measured in x-ray diffraction experiments, while the phases are "lost". However, Andrew developed approaches that allow for these "lost" phases to be numerically recovered after the fact. This in turn allows to "look" inside of materials and devices with unprecedented nanoscale resolution. In addition to 3D-tracking the diffusion of Li ions through a single micron-sized grain of battery electrode, Andrew captured the formation and dynamics of defects formed inside material after rapid cycling. The motion of these dislocation can then be correlated with Li diffusion and structural phase transitions that typically occurs in these materials at high voltages, as result of Li intercalation.
Perhaps the most surprising discovery is that these materials become "auxetic" as the battery is charged - exhibiting a negative Poisson ratio. This means that applying compressive stress along one axis, the material also compresses along orthogonal axes - instead of typically observed expansion along those directions. These results appeared in Science magazine in June. (A. Ulvestad, A. Singer, J. N. Clark, H. M. Cho, J. W. Kim, R. Harder, J. Maser, Y. S. Meng,and O. G. Shpyrko, Science 348 (6241), 1344-1347 (2015), http://www.sciencemag.org/content/348/6241/1344.full).
Andrew has joined UCSD PhD program in the Fall of 2012 and has graduated in less than 3 years, after publishing 7 papers as first author, as well as several additional publications as contributing author. Andrew's work at UCSD was supported by the Department of Energy (PI: Oleg Shpyrko).
Since defending his PhD Thesis in June of 2015, Andrew is currently holding a prestigious Director's Named Postdoctoral Fellowship at Argonne National Lab near Chicago, where he continues application of advanced x-ray imaging methods to a wide range of materials.
Funding: This fellowship was made possible by the generosity of the Inamori Foundation.