Lessons learned from operating a solid oxide electrolysis cell at -1.25 a/cm² for one year

Conventional Ni/yttria stabilized zirconia (YSZ) fuel electrode supported solid oxide electrolysis cells (SOECs) demonstrate acceptable long-term durability when operated at below -1 A/cm². These cells suffer however severe degradation at above -1 A/cm², where a large part of the cell resistance increase is associated with the Ni/YSZ electrode. In this work, by introducing Ce_0.8Gd_0.2O_2-δ (CGO) nanoparticles into the Ni/YSZ electrode, we reduce the cell degradation down to 39 mV/kh when operated at 810 °C and -1.25 A/cm². A steam supply failure at 4000 h causes certain damage to the cell, resulting in higher degradation in the second half of the one-year period. A degradation-mitigation strategy is successfully tried out by increasing the operating temperature to 836 °C eventually. The test is successfully terminated after reaching one year, demonstrating an average degradation rate of 39 mV/kh over the one-year period. The current work shows the potential of modifying conventional SOEC cells for use in high current density electrolysis applications.