High-temperature degradation of tetragonal zirconia in solid oxide fuel and electrolysis cells: A critical challenge for long-term durability and a solution

Solid oxide fuel and electrolysis cells (SOCs) are promising devices for efficiently generating electricity and hydrogen/syngas, respectively. The preferred cell configuration by many industrial developers consists of a Ni (O)-3YSZ fuel electrode support or a 3YSZ electrolyte support, which allows the manufacturing of large-area cells. 3YSZ, like many other transformable tetragonal zirconia ceramics, is well-known to be susceptible to hydrothermal degradation at temperatures below 400 degrees C (LTD) but is widely believed to withstand this degradation at higher temperatures. In this work, we present our recent finding that 3YSZ is, in fact, susceptible to hightemperature degradation (HTD) after operation over 8500-10,000 h. The degradation leads to substantial embrittlement of the cells. In addition, we report on the excellent resistance to LTD and HTD of a newly developed fine-grained Ni-3YSZ support. This study highlights the importance of using HTD-resistant tetragonal zirconia ceramics in developing the next generation of strong and durable ceramic-supported SOCs.