Title

The role of microstructure on transport phenomena in fuel cells

Date of Completion

January 2010

Keywords

Alternative Energy|Engineering, Chemical|Engineering, Mechanical|Engineering, Materials Science

Degree

Ph.D.

Abstract

The Solid Oxide Fuel Cell (SOFC) and Alkaline Membrane Fuel Cell (AMFC) are two technologies that may enable more efficient and scalable conversion of chemical energy stored in a given fuel. Electrical power is provided from these devices when the chemical energy stored in the respective fuel(s) and oxidant(s) are electrochemical converted to electrical power, which can be used to perform external work. The SOFC and AMFC are attractive as energy conversion devices because they present opportunities to use a variety of energy dense and easy-to-store hydrocarbons fuels, such as methane and primary alcohols, respectively. Oxygen from ambient air is available as an oxidant for both devices. However, both of these technologies have limitations in the forms of performance, degradation, stability, reliability, and cost. ^ Complex heterogeneous architectures are used to support the transport and reaction processes; however, these architectures introduce many of these limitations in these systems. The functional processes that these architectures support are not only complex, but occur and are coupled across a variety of time and length scales. From an engineer's perspective, the coupling of the transport and reaction processes is realized at the fundamental level of the complex heterogeneous structures. Therefore, an examination of the nature, role, and impact of the heterogeneous structure at these scales is necessary to address issues related to the present limitations. ^ It is the interaction at these fundamental scales that are the focus of the efforts presented. Specific items undertaken include the ( i.) characterization of the heterogeneous electrode microstructure, (ii.) development of new characterization tools that can provide new insights into the nature and impact of this structure, ( iii.) development of non-empirical transport and reaction models, (iv.) application of these transport models to understand coupling between the microstructure, interfacial, and transport processes, and (v.) exploring conductive transport in the low temperature AAEM, which permits transport in the presence of a polar solvent, namely water. ^