Refreshments in ETRL- 10:30-11:00
Dr. Anil V. Virkar, Distinguished Professor
University of Utah, Department of Materials Science & Engineering
Transport-Induced Failure of Electrochemical Devices: Batteries and Electrolyzers
Many electrochemical devices such as batteries, fuel cells, electrolyzers, etc. degrade over time and under various operating conditions. In batteries containing series-connected cells, degradation often occurs if one or more cells exhibit different characteristics than the rest of the cells. Also, batteries are more prone to degradation during charging. Problems with laptop batteries are well known. Fuel cells (especially stacks) also undergo degradation during operation. There is considerable literature on solid oxide electrolyzers, which too degrade under certain operating conditions. Degradation in these devices may manifest as increase in resistance, loss of capacity, or both. In some instances, complete electrode delamination has been observed. In some cases, electrolyte instability may occur. In lithium-ion batteries, lithium dendrites can form. While there are several reasons for degradation, the observation that many electrochemical devices degrade suggests that there may be a common underlying reason which is applicable to all such electrochemical systems. This talk is on the degradation of such electrochemical devices which can occur under transport. A key conclusion is that the chemical potential of an electrically neutral species within the electrolyte corresponding to the mobile ion, may lie outside the range covered by the values at the electrodes (reservoirs), and this can lead to transport-induced instability. Specific examples of solid oxide electrolyzers and lithium ion batteries will be addressed.
Anil Virkar is Distinguished Professor and H. Kent Bowen Endowed Chair in the Department of Materials Science & Engineering at the University of Utah. He is a cofounder of Versa Power Systems, (VPS) (www.versa-power.com), a Colorado-based company with operations in Calgary (later acquired by FuelCell Energy). He was also a founding member of Ceramatec, Inc., a small company based in Salt Lake City, Utah, now a subsidiary of CoorsTek. He received B.Tech. (Hons.) in Metallurgical Engineering from Indian Institute of Technology, Mumbai, India (1967); M.S. in Engineering Mechanics from Louisiana State University in (1969); and Ph.D. from Northwestern University in Materials Science in (1973). His research is in fuel cells, batteries, multi-species transport and the role of non-equilibrium thermodynamics in the stability of electrochemical devices. His early work was on fabrication of ceramics (oxides and non-oxides), phase transformation mechanisms and kinetics, and fracture mechanics. He has to date published over 250 refereed papers and has more than 40 patents to his credit. He has supervised PhD and MS research of over 50 candidates to date. His current funding is primarily from DOE and NSF.