Performance and Durability of High Temperature Steam Electrolysis: From Single Cell to Short-Stack Scale

A new stack designed for High Temperature Steam Electrolysis is presented here. It integrates grids as contact layers and an optimized sealing solution. The design has first been validated at the single repeat unit (SRU) level before operating a 5-cell stack for a performance and durability test. Performance results show that i-V curves at the SRU and stack level are very close to those obtained at the single cell level, highlighting an optimized design and more specifically good contacts between the interconnects and the cells. Very high performances have been obtained (-1 A/cm(2) at 1.2-1.3 V at 800 degrees C) at the stack level and more than 99% of the produced hydrogen has been collected. A durability test of 2700 hours has been carried out with a current density of -0.5 A/cm(2) and a steam conversion rate of 25%. Degradation rates around 7-13%/kh for the 3 central cells have been measured during this test.