Degradation of solid oxide electrolysis stacks in seawater and deionized water electrolysis

Abstract

Solid oxide electrolysis cells(SOECs) provide an efficient solution for seawater electrolysis. The electrolysis stack is the core component of a SOEC system. A comprehensive understanding of degradation mechanisms of the stack when operated in a seawater environment is crucial for optimizing its application. This study conducts a comparative analysis of the performance of SOEC stacks in seawater versus deionized water. The findings indicate that, while the initial instantaneous performances of the stacks are similar in both environments, significant differences emerge during prolonged operation. Over a 500-h stable operation period, the overall degradation rates of the electrolysis stacks were found to be 6.7 % in deionized water, compared to 12.3 % in seawater, indicating that the stacks and their components experience more substantial degradation when exposed to seawater. Notably, a more pronounced loss of nickel from the hydrogen electrode of the cells. Which may be the major reasons for the larger degradation of performance. This work provides valuable insights for the research and application of solid oxide electrolysis cells in seawater hydrogen production.