Solid Oxide Cells for Power-to-X: Materials, Applications & Challenges

Kurzfassung

In a context of climate change, the need for more carbon efficient technologies for energy storage and energy efficiency is pressing. Owing to high temperature operation and fast electrode kinetics reaction Solid Oxide Cells (SOC) present the unique feature, to be capable of reversible operation, meaning fuel cell mode and electrolysis mode. While the latter allows primarily efficient conversion of steam into Hydrogen, it also presents the huge benefit of allowing co-electrolysis of CO2 and H2O into a synthetic gas made of CO and H2 that can be processed downstream into valuable chemicals via the Fischer-Tropsch process. As practical operation requires a stable operation, it is of crucial importance to understand the behavior of those cells. The technology is mature for fuel cell mode, however operating in electrolysis mode implies new boundary conditions that may trigger novel degradation mechanism to be understood and mitigated in order to develop efficient and durable solid oxide cells for Power-to-X applications. In this presentation, the behaviour of SOC electrolysis and co-electrolysis and reversible operation is shown for operation up to 10 000 hours. The most significant degradation phenomena specific to electrolysis operation and that affect the durability of electrochemical cells (for instance: nickel migration phenomena, microstructure alteration, poisons…) are presented in terms of physico-chemical, materials and microstructural aspects and discussed. The relative sensitivity of the different cell architectures to the various degradation phenomena that are monitored and reported in this presentation is discussed. Finally, some new materials combinations candidate for the next generation SOC with improved performance and characteristics, will be presented.