Page 9 - High Temperature Solid Oxide Fuel Cells Fundamentals, Design and Applications

vi High Temperature Solid Oxide Fuel Cells: Fundamentals, Design and Applications

3.4 Thermodynamic Definition of a Fuel Cell Producing
Electricity and Heat 66
3.5 Thermodynamic Theory of SOFC Hybrid Systems 69
3.6 Design Principles of SOFC Hybrid Systems 77
3.7 Summary 80
References 81

Chapter 4 Electrolytes
4.1 Introduction 83
4.2 Fluorite-Structured Electrolytes 83
4.3 Zirconia-Based Oxide Ion Conductors 89
4.4 Ceria-Based Oxide Ion Conductors 92
4.5 Fabrication of ZrOz and Ce02-Based Electrolyte Films 94
4.6 Perovskite-S tructured Electrolytes 96
4.6.1 LaA103 97
4.6.2 LaGa03 Doped with Ca, Sr andMg 99
4.6.3 LaGaOs Doped with Transition Elements 104
4.7 Oxides with Other Structures 106
4.7.1 Brownmillerites (e.g. Ba2InzO6) 106
4.7.2 Non-cubic Oxides 108
4.8 Proton-Conducting Oxides 110
4.9 Summary 112
References 112

Chapter 5 Cathodes
5.1 Introduction 119
5.2 Physical and Physicochemical Properties of
Perovskite Cathode Materials 120
5.2.1 Lattice Structure, Oxygen Nonstoichiometry,
and Valence Stability 120
5.2.2 Electrical Conductivity 123
5.2.3 Thermal Expansion 125
5.2.4 Surface Reaction Rate and Oxide Ion
Conductivity 126
5.3 Reactivity of Perovskite Cathodes with Zr02 130
5.3.1 Thermodynamic Considerations 130
5.3.1.1 Reaction ofperovskites with the
Zirconia Component in YSZ 130
5.3.1.2 Reactionofperovskite with the
yttria (dopant) component in YSZ 130
5.3.1.3 Interdiffusion between Perovskite
and Fluorite Oxides 131
5.3.2 Experimental Efforts 132
5.3.3 Cathode/Electrolyte Reactions and Cell
Performance 134
5.3.4 Cathodes for Intermediate Temperature SOFCs 13 6