Critical Causes of Degradation in Integrated Laboratory Scale Cells during High Temperature Electrolysis

摘要: An ongoing project at Idaho National Laboratory involves generating hydrogen from steam using solid oxide electrolysis cells (SOEC). This report describes background information about SOECs, the Integrated Scale (ILS) testing of solid-oxide stacks, ILS performance degradation, and post-test examination SOECs by various researchers. The test was a 720- cell, three-module comprised 12 stacks 60 each. A peak H2 production rate 5.7 Nm3/hr achieved. Initially, module area-specific resistance ranged 1.25 Ocm2 to just over 2 Ocm2. Total decreased steady state value 0.7 Nm3/hr. decrease primarily due cell degradation. Post Ceramatec showed that electrode appeared be in good condition. oxygen evolution does show delamination operation an apparent foreign layer deposited electrolyte interface. Argonne O2-electrode delaminated near edge. One possible reason for this is excessive pressure buildup with high O2 flow over-sintered region. According post Massachusetts Institute Technology, electrochemical reactions have been recognized asmore » one prevalent causes their Specifically, two important degradation mechanisms were examined: (1) transport Crcontaining species steel interconnects into LSC bond layers (2) cation segregation phase separation layer. INL conducted workshop October 27, 2008 discuss SOEC stack. Generally, it agreed following are major issues relating SOECs: • Delamination on steam/O2-electrode side Contaminants (Ni, Cr, Si, etc.) reaction sites (triple boundary) Loss electrical/ionic conductivity electrolyte.« less