A "Transforming Energy" Lecture by Eric Wachsman
April 16, 2009

Abstract

Fuel cells offer great promise as a clean and efficient process for directly converting chemical energy to electricity while providing significant environmental benefits. Among the different fuel cell technologies, solid oxide fuel cells (SOFCs) are unique in their ability to operate both within the current fossil fuel based energy infrastructure and as part of a future proposed hydrogen fuel infrastructure. Unfortunately, SOFC cost and reliability are limited by high operating temperature requirements. With the current state of the art SOFCs, performance at lower temperature is limited by cathode polarization.

In order to understand the various mechanistic contributions to cathode polarization and apply this knowledge to development of lower-polarization/lower-temperature SOFC cathodes, we have embarked on a multi-faceted, multi-disciplinary approach to deconvolute the various contributions to SOFC cathode polarization. This approach includes FIB/SEM to quantify the cathode microstructure (in terms of tortuosity and porosity for gas diffusion, solid-phase surface area for gas adsorption/surface diffusion, and triple phase boundaries for the charge transfer reaction) and heterogeneous catalysis techniques (temperature programmed desorption and reaction) and O-isotope exchange to evaluate the O2 reduction mechanism at the gas-solid reaction interface. These results are then combined (and contrasted) with the more conventional electrochemical polarization techniques (impedance spectroscopy and I-V behavior) to try and elucidate each of the mechanisms as a function of material and microstructure. The progress to date on this investigation will be presented.

In addition, an overview of related solid state ionics research at the UF - Department of Energy High Temperature Electrochemistry Center and a brief introduction to the Florida Institute for Sustainable Energy will be presented.

Biography

Eric Wachsman is the director of the Florida Institute for Sustainable Energy, director of the U.S. Department of Energy High Temperature Electrochemistry Center at the University of Florida, and the Rhines Chair Professor of Department of Materials Science & Engineering. He received a Ph.D. in materials science and engineering from Stanford University, and a B.S. in chemical engineering from the University of California at Berkeley. Prior to coming to the University of Florida, Wachsman rose through the ranks from post-doctorate to senior scientist at SRI International.

Wachsman has focused his career on developing advanced, efficient, energy conversion devices and technologies. His research is on ionic transport in solids and the heterogeneous electrocatalysis at their surface. This research includes the development of solid oxide fuel cells, gas separation membranes, solid-state gas sensors, the electrocatalytic conversion of CH4, and the post-combustion reduction of NOx using advanced ion conducting materials.

Wachsman is a Fellow of The Electrochemical Society (ECS) and the past chair of the High Temperature Materials Division of ECS. In addition, he is editor-in-chief of Ionics, formerly an associate editor of Journal of the American Ceramic Society, councilor of the Florida Section of the American Ceramic Society, and a member of the American Chemical Society, the International Society for Solid State Ionics and the Materials Research Society. He has more than 140 publications and eight patents on ionic and electronic transport in ceramics, their catalytic properties, and device performance.

Wachsman is also a frequent invited panelist on fuel cell and hydrogen energy research, ranging from the U.S. Department of Energy "Fuel Cell Report to Congress" and "Basic Research Needs Related to High Temperature Electrochemical Devices for Hydrogen Production, Storage and Use," to the National Science Foundation "Workshop on Fundamental Research Needs in Ceramics," NATO "Mixed Ionic-Electronic Conducting (MIEC) Perovskites for Advanced Energy Systems,” and the National Academies “Global Dialogues on Emerging Science and Technologies."