Post-test evaluation of oxygen electrodes from solid oxide electrolysis stacks☆

Modeling Degradation in Solid Oxide Electrolysis Cells

“…1,16,17,18,19 There also are some reports of relatively stable operation for several hundred hours. 44,45,46 The objective of the following discussion is to determine if there were significant differences among the various reported studies in the context of the model described here.…”

“…1,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26 Typical SOEC consists of an oxygen ion conducting a solid electrolyte such as YSZ sandwiched between two electrodes; steam-H 2 electrode (which is the cathode in SOEC) made typically of nickel + YSZ oxygen electrode (which is the anode in SOEC) made typically of an electron (hole) conducting perovskite such as Sr-doped LaMnO 3 (LSM) mixed with YSZ. The cell is typically operated over a temperature range from 800 to 900°C.…”

“…One mode of failure in SOECs, has been reported to be the occurrence of delamination of the oxygen electrode. 1,16,17,18,19 As an example of the morphology of oxygen electrode delamination in SOEC, Figure 4 shows a scanning electron microscope (SEM) micrograph of a delaminated oxygen electrode. 19 showing oxygen electrode delamination along the oxygen electrode/electrolyte interface.…”

“…Indeed, experimental results in several studies have shown that delamination often occurs along the oxygen electrode/electrolyte interface in the electrolyzer mode. 1,16,17,18,19 This is an additionally remarkable result, as it suggests that the intuitively obvious approach of trying to develop an electrolyte material with the highest possible ionic transference number may in fact be counterproductive from the standpoint of stability. Table 1 shows that delamination is likely for -4 Scm -1 , which also means delamination is likely for a 10-micronthick electrolyte with electronic conductivity less than 1.25×10 -4 Scm -1 .…”

Degradation in Solid Oxide Cells During High Temperature Electrolysis

“…Some cells were examined by Argonne National Laboratory (ANL); published results from that examination are also given in Section 4.4 and Figure 17 [Mawdsley et al, 2007]. In an effort to understand degradation in Ceramatec SOEC and its distinction from degradation in SOFC, post-mortem of the electrolysis cells was performed at ANL and Massachusetts Institute of Technology (MIT); Carter et al 2008).…”