Dynamic operation of metal-supported solid oxide electrolysis cells

Symmetric-structure metal-supported solid oxide fuel cells and electrolysis cells (MS-SOFCs, MS-SOECs) offer several advantages over conventional solid oxide cells, including the use of inexpensive materials, high mechanical strength, and rapid ramp-up ability. Aggressive operation of MS-SOCs in fuel cell mode is well-established, including extremely fast start-up, redox tolerance, and imbalanced pressure. Here, we extend dynamic operation to MS-SOCs in SOEC mode with high steam content for both small button cells and a large rectangular cell, including: steam cycling, thermal cycling, redox cycling and power cycling. Steam cycling entailed switching between 3:97 and 50:50 steam:hydrogen ratio. For thermal cycling, the temperature was rapidly varied between 150 °C and 700 °C for 50 cycles. Redox cycling involved switching the steam side gas between 50 % humidified H2 and 50 % humidified N2 for 5 cycles. Power cycling was performed by operating the cell under variable current density, resulting in cell voltage between 1.3 V and 2.8 V. Degradation rates for each testing strategy were compared to a baseline cell, and found to be similar. The excellent tolerance to dynamic operation increases confidence that MS-SOECs will be compatible with dynamic or intermittent renewable resources.