Using AE and X-Ray Diffraction to Monitor Electrochemical Materials

Dr. Kevin Rhodes, a doctoral student from the University of Tennessee and Oak Ridge National Laboratory, has continued his research on the degradation of lithium-ion battery materials. Using different MISTRAS equipment since his last study and a new research approach, Kevin has uncovered more information on the correlation of Acoustic Emission (AE) with these materials, as well as others.

Building upon recent successes using acoustic emission to identify and study degradation events in electrochemical energy storage devices and battery electrode materials, Kevin and the other members of his team at Oak Ridge National Laboratory have been hard at work studying AE from new materials and modeling their findings.

For this research, Kevin used a Micro-II PCI-2-8(AC) system in which they have three PCI-2 boards for a total of six channels. They use a mixture of S9220 and PICO sensors into 2/4/6 preamps, while running AEwin PCI2-4 software and post processing and filtering in AE-WIN-POST.

Through the use of a novel in situ AE-XRD, AE signals have been linked to the stress state in active materials as they are cycled. This has allowed for the correlation of lattice stress and strain with the onset time for fracture events which can lead to a loss of performance in the cell.

Furthermore, with the assistance of Dr. Sergiy Kalnaus, the team has deepened the understanding of how and why these fracture events occur by modeling the probability of damage in the materials and comparing this with experimental findings.

In August 2011, Kevin Rhodes was awarded a PhD in Materials Science and Engineering from The University of Tennessee for his work on AE and XRD of lithium ion batteries. Additionally he is the recent recipient of the 2011 American Crystallographic Association Margaret C. Etter Student Lecture Award in Powder Diffraction for this presentation dealing with the XRD and AE of cathode materials for lithium ion batteries.