Development of Al2O3/glass-based multi-layer composite seals for planar intermediate-temperature solid oxide fuel cells

In this paper, the novel multi-layer composite seals for planar solid oxide fuel cells are studied. The composite seals with sandwiched structure include Al2O3-based tape as support and glass-ceramic slurry as binder connecting the interface of the neighboring components. The result finds out that glass-ceramic slurry with 20 wt% Al2O3 has the suitable strength and deformability. The thermal cycle characteristics are greatly improved by using the multi-layer composite seals, and the corresponding leakage rates are lower than 0.025 sccm cm−1 for 20 thermal cycles at the inlet pressure ranging from 0.5 psi to 2 psi. SEM investigations show a very compact and good adhesion between the neighboring components, which can minimize the leakage paths. Single cell testing is used to examine the performance of the seals. The value of open circuit voltage is 1.17 V. At the constant discharge current density of 0.37 A cm−2, the voltage is stabilized at about 0.85 V for 50 h. The results demonstrate that the novel multi-layer composite seals are good candidate for SOFC application.