Degradation of Metal-supported Cells with Ni-YSZ or Ni-Ni_3Sn-YSZ Anodes Operated with Methane-based Fuels

摘要

Ni-Ni_3Sn-YSZ and Ni-YSZ anodes were incorporated into metal-supported SOFCs that consisted of a porous metal support (Sandvik Sanergy), samaria-doped ceria (SDC) barrier layer, anode as previously described, YSZ electrolyte, and La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)-SDC cathode. Cells were tested at 750°C with air as the oxidant and fuel consisting of 65% CH_4, 32% H_2, and 3% H_2O. The cells were held at a current density of 0.15 A·cm~(-2) for 500 hours. The cell without tin in the anode began to degrade after approximately 200 hours and catastrophically failed at approximately 425 hours. After testing, we observed that the anode had disintegrated, and as a result, the electrolyte and cathode were completely detached from the metal support. On the other hand, the cell with an anode containing tin did not catastrophically fail, and the cell remained intact after 500 hours of operation. Over 500 hours, the cell potential degraded from 0.841 V to 0.743 V, and scanning electron micrographs showed that the anode had delaminated from the electrolyte in some areas. Nonetheless, the cell with the Ni-Ni_3Sn-YSZ anode degraded significantly less than the cell containing a Ni-YSZ anode, suggesting that the addition of Ni_3Sn to an anode could be a useful strategy for improving durability of SOFC anodes using hydrocarbon fuels.