Ceria-based Nanocomposite Electrolyte for Low-Temperature Solid Oxide Fuel cells

.................................................................................................................................................. I LIST OF PAPERS ...................................................................................................................................... III TABLE OF CONTENTS .......................................................................................................................... VII 1 INTRODUCTION ................................................................................................................................... 1 1.1 Fuel cell ............................................................................................................................. 2 1.2 Solid oxide fuel cell (SOFC) ............................................................................................. 4 1.2.1 General Introduction of SOFC ............................................................................................... 4 1.2.2 Materials for SOFC components ............................................................................................ 5 1.2.3 Challenges and limitations of SOFC ...................................................................................... 9 1.3 Development of low-temperature SOFC ........................................................................ 10 1.4 R&D of new electrolyte materials for LTSOFC ............................................................. 11 1.4.1 Nanotechnology approach .................................................................................................... 11 1.4.2 Composite approach ............................................................................................................. 12 1.5 Motivation and objectives ............................................................................................... 15 2 EXPERIMENTAL ................................................................................................................................. 16 2.1 Core-shell SDC/Na2CO3 nanocomposite ........................................................................ 16 2.1.1 Fabrication of core-shell SDC/Na2CO3 nanocomposite ....................................................... 16 2.1.2 Thermal stability test of core-shell SDC/Na2CO3 nanocomposite ....................................... 16 2.2 SDC nanowires based nanocomposite ............................................................................ 17 2.2.1 A novel synthetic route for SDC nanowires ......................................................................... 17 2.2.2 Fabrication of SDC nanowires/Na2CO3 nanocomposite ...................................................... 17 2.3 Characterization .............................................................................................................. 17 2.4 Single cell fabrication and electrochemical measurements ............................................. 19 2.4.1 Conductivity measurement ................................................................................................... 19 2.4.2 Fuel cell fabrication and performance test ........................................................................... 20 3 RESULTS AND DISCUSSION ............................................................................................................ 21 3.1 Core-shell SDC/Na2CO3 nanocomposite electrolyte ...................................................... 21 3.1.1 Morphology and structure studies ........................................................................................ 21 3.1.2 Thermal stability study ......................................................................................................... 22 3.1.3 Superionic conductivity........................................................................................................ 25 3.1.4 Fuel cell performance and durability test ............................................................................. 26 3.2 SDC nanowires/ Na2CO3 nanocomposite electrolyte ...................................................... 28 3.2.1 Synthesis Mechanism of SDC nanowires ............................................................................ 28 3.2.2 Characterization of lanthanide citrate precursor ................................................................... 30 3.2.3 Morphology and structure study of SDC nanowires ............................................................ 31 3.2.4 Characterization of SDC nanowires/Na2CO3 nanocomposite .............................................. 33 3.2.5 Fuel cell test and electrochemical study ............................................................................... 34 4 CONCLUSIONS .................................................................................................................................... 37 FUTURE WORK ......................................................................................................................................... 38 ACKNOWLEDGEMENTS ........................................................................................................................ 39 REFERENCES ............................................................................................................................................ 40