Efficiency and stability of seawater electrolysis through flat-tube solid oxide cell stack without air

Efficiency and stability are critical for solid oxide electrolysis cell (SOEC) applications. In this study, the effect of airless on the efficiency and stability of electrolysis seawater in a flat-tube SOEC stack is investigated. Considering gas heating loss, the maximum electrolysis efficiency of the stack with airless is 94.7 %, while that of the stack with air is 69.8 %. The 2-cell SOEC stack is operated for 500 h in airless at 300 mA/cm2 with an efficiency of 89.2 %. The degradation rate of Cell 1 and Cell 2 is 2.5 %/kh and 4.8 %/kh, respectively. The overall degradation of the stack is less than that of cell, which could be attributed to the improved interfacial contact between interconnect and cell inside the stack. The results show that the flat-tube SOEC stack has high efficiency and excellent stability for seawater electrolysis with airless, which provides a reference for efficient conversion and storage of offshore power.