The Ni-YSZ interface

SOFC principle of operation......Page 9
Electrolyte......Page 10
Electrical losses/electrochemical efficiency......Page 11
Previous studies on Ni point electrodes......Page 12
Thesis layout......Page 13
Nickel wires......Page 14
Geometry of the set-up......Page 15
Electrochemical measurements......Page 16
Other experiments/analyses......Page 18
SEM/EDS......Page 19
TOF-SIMS......Page 20
Samples with impure nickel wires as electrodes......Page 21
Contact areas on the YSZ pellets......Page 22
Structure with holes in the grains (type c)......Page 23
Hill and valley/pyramidal tips transition structure (type d)......Page 24
Hill and valley structure/ pyramidal tips (type b)......Page 25
The rim ridge......Page 26
Other features concerning the YSZ contact area......Page 27
The nickel wires......Page 29
Contact areas on the YSZ pellet......Page 30
Non-polarised samples......Page 31
Anodically polarised samples......Page 34
Thermally annealed sample......Page 37
Impurity influence on the formation of hill and valley structures......Page 40
The rim ridge......Page 41
Influence of current......Page 42
Conclusion on morphology......Page 43
Results of XPS analysis of YSZ......Page 44
Impure nickel electrodes......Page 46
Contact areas on YSZ pellets......Page 47
Pure nickel electrodes......Page 49
Contact areas on YSZ pellets......Page 50
Overview scans......Page 51
The contact area interior......Page 52
The contact area border......Page 55
XPS analyses......Page 56
Impurity segregation from the Ni to the interface......Page 58
Impurities in the pure interface......Page 59
Rim ridge formation......Page 60
Conclusion on impurities......Page 63
Series resistance......Page 64
Impure nickel wires as electrodes......Page 65
Pure nickel wires as electrodes......Page 66
Electrical contact areas......Page 67
Impure nickel wires as electrodes......Page 69
Multiple polarisations......Page 71
Pure nickel wires as electrodes......Page 72
Spectra from samples with impure electrodes......Page 73
Spectra from samples with pure electrodes......Page 74
Capacitance......Page 79
Chronoamperometry......Page 81
Potential sweeps......Page 83
Trends for OCV conditions......Page 84
Polarisation resistance values......Page 85
Conclusion on electrical measurements......Page 86
Impurities and resistance......Page 87
Structures and polarisation......Page 90
Final Conclusions......Page 91
Outlook......Page 92
References......Page 93
List of publications......Page 97