Professor John Lambros, University of Illinois

Three dimensional studies of particle fracture in Si- and Sn-based Li+ composite electrodes
When Jun 19, 2014
from 02:00 PM to 03:00 PM
Where LR8, IEB Building, Engineering Science
Contact Name
Contact Phone 01865-283302
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Silicon or tin based electrodes for lithium ion (Li+) batteries are of significant interest because of their potential to be high capacity alternatives to the commonly used graphitic carbon anodes. A drawback to their use, however, is the inevitable particle debonding and fracture that occurs as a result of the volumetric expansion by the host particles upon lithiation of the anode. In this work we use X-ray microcomputed tomography to visualize the evolution of the internal microstructure of both Si-based and Sn-based electrodes before and after lithiation either in complete cycles or in partial lithiation steps. Using X-ray microtomography, we are able to visualize with image resolution around 1 μm/voxel material evolution, generating 3D images of up to 1 billion voxels. From these images we develop a threshold edge detect method to perform 3D volumetric measurements of particle expansion and we measure up to 290% volume expansion in Si after 100% theoretical lithiation. Similar, though less, volume expansion is seen in Sn particles after lithiation. However, the details of particle fracture and particle/matrix debonding differ between the two materials, with Si particles fragmenting whereas Sn particles crack radially. In addition to image analysis we wish to perform internal measurements of the electrode composites’ strain using three dimensional (3D) digital volume correlation (DVC). 3D-DVC measures displacement and strain inside a material subjected to deformation, which in this case is caused by the cyclic lithiation-delithiation process of the battery charging and discharging. Our high-performance DVC algorithm uses parallel computing to help with computation time and memory management issues so that large scale DVC problems can be run. The algorithm is first implemented in surrogate composite materials of glass particles in a PDMS matrix, and is then extended to the electrochemically active Si-based and Sn-based electrodes.

 

Short bio – John Lambros: In 1988 I received a B.Eng. degree in Aeronautics from the Imperial College of Science and Technology of the University of London. I then spent approximately 7 years at Caltech obtaining an M.S. degree in 1988, a Ph.D. degree in 1994 and, finally, one year as a postdoctoral research fellow, all at the Graduate Aeronautical Laboratories (GALCIT). In August of 1995 I joined the Mechanical Engineering department of the University of Delaware as an Assistant Professor. I moved to the Aerospace Engineering department of the University of Illinois at Urbana-Champaign in 2000 as an Associate Professor, and became a full professor in this department in 2007. In 1999 I received an NSF CAREER award. Between 1999-2005 I was Associate Editor for Experimental Mechanics, in 2009 I became a fellow of the American Society of Mechanical Engineers, and in 2013 a fellow of the Society for Experimental Mechanics. Currently I serve as an Associate Editor for the ASME Journal of Applied Mechanics, am directing the Army funded MURI on Nonlinear Stress Wave Mitigation, and am serving as the Associate Department Head for Graduate Studies in the Aerospace Engineering Department at UIUC.