A novel
micro-tubular solid oxide fuel cell (SOFC) design with an inert support was
proposed for operation on direct hydrocarbon fuels with an improved stability.
In this design, the inert support also serves as a diffusion barrier between
the fuel stream and Ni cermet anode. The barrier effect leads to higher local
steam to carbon ratios in the anode, thus inhibiting carbon deposition. To
demonstrate this concept, we fabricated micro-tubular SOFCs with a porous
yttria-stabilized zirconia (YSZ) support. Ni, Ni-scandia-stabilized zirconia
(ScSZ), ScSZ, strontium-doped lanthanum manganite (LSM)–ScSZ, and LSM were used
as the anode current collector, anode, electrolyte, cathode, and cathode
current collector, respectively. Good electrochemical performance was achieved
with hydrogen and methane fuels in a temperature range 600–750 °C. Continuous
cell operation on direct methane fuel for >40 h at 750 °C under moderate
current densities delivered stable voltage without any evident performance
degradation due to carbon deposition. The absence of carbon deposition on the
anode and anode current collector layers was also confirmed by scanning
electron microscope images and energy-dispersive X-ray spectra. We further
discuss oxidation mechanism of the direct methane fuel and removal of the
carbon possibly formed in the anodic layers during stability testing.
Click here to access the full article published in Journal of Solid State Electrochemistry.
