The development of micro-tubular solid oxide fuel cells (SOFCs) has received more
and more attention recently due to a number of advantages of this configuration, such
as high volumetric power output and rapid start-up/shut-down. Previously, the
fabrication of micro-tubular SOFC was achieved through multiple-step processes,
which involves at least one sintering in each step, making the cell fabrication time consuming
and costly.
For a more economical fabrication of micro-tubular SOFC with more reliability and
flexibility in quality control, an advanced dry-jet wet extrusion technique, i.e. a phase
inversion-based co-extrusion process, followed by co-sintering and reduction
processes has been developed and systematically investigated in this thesis. At the
beginning of the study, a dual-layer hollow fibre which consists of a ceriumgadolinium
oxide (CGO) electrolyte outer layer of approximately 80 μm supported by
an asymmetric nickel (Ni)-CGO anode inner layer, is successfully fabricated using
this technique. The resultant cell of the corresponding dual-layer hollow fibre
produces the maximum power density of 0.34-0.68 W cm-2 at 550-600 oC.
Improvement on the structure of the dual-layer hollow fibres is performed by reducing
the electrolyte layer thickness to as thin as 10 μm and the maximum power density of
the corresponding cell increases to about 1.11 W cm-2 at 600 oC. However, the value
of power density is still slightly lower than what have been previously reported in
the literature. One of the major reasons for such lower power output is the less
effective porosity in the anode layer of hollow fibres. Therefore, the optimisation on
anode porosity of the dual-layer HF is carried out and resulting in the outstanding power output of about 2.32 W cm-2 at 600 oC. This result indeed highlights the
advantage of co-extrusion/co-sintering as a fabrication technique in developing high
quality micro-tubular SOFC.