CaltechTHESIS
  A Caltech Library Service

Solid-oxide fuel cell electrode microstructures : making sense of the internal framework affecting gas transport

Citation

Hanna, Jeffrey (2010) Solid-oxide fuel cell electrode microstructures : making sense of the internal framework affecting gas transport. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:06072010-090420975

Abstract

Optimal electrodes for solid-oxide fuel cells will combine high porosity for gas diffusion, high phase connectivity for ion and electron conduction, and high surface area for chemical and electrochemical reactions. Tracer-diffusion simulations are used to gain a better understanding of the interplay between microstructure and transport in porous materials. Results indicate that the coefficient of diffusion through a porous medium is a function of the details of the internal geometry (microscopic) and porosity (macroscopic). I report that current solid-oxide fuel cell electrodes produced from high-temperature sintering of ceramic powders severely hinder gas transport because the resulting structures are highly tortuous, complex three-dimensional networks. In addition, poor phase connectivities will assuredly limit ion and electron transport, as well as the density of active sites for power-producing reactions. With new access to a wide range of technologies, micro- and nano-fabrication capabilities, and high-performance materials, there is a new ability to engineer the fuel cell electrode architecture, optimizing the physical processes within, increasing performance, and greatly reducing cost per kilowatt. Even simple packed-sphere and inverse-opal architectures will increase gas diffusion by an order of magnitude, and provide a higher level of connectivity than traditional powder-based structures.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Tracer diffusion; SOFC; Triple-phase boundary; Tortuosity; Anode microstructure; Inverse opal
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Mechanical Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Shepherd, Joseph E.
Thesis Committee:
  • Hunt, Melany L.
  • Haile, Sossina M.
  • Blanquart, Guillaume
  • Shepherd, Joseph E. (chair)
Defense Date:27 May 2010
Author Email:jhanna (AT) caltech.edu
Record Number:CaltechTHESIS:06072010-090420975
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:06072010-090420975
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:5923
Collection:CaltechTHESIS
Deposited By: Jeffrey Hanna
Deposited On:08 Jun 2010 15:50
Last Modified:26 Dec 2012 04:28

Thesis Files

[img]
Preview
PDF - Final Version
See Usage Policy.

18Mb

Repository Staff Only: item control page