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Page 12 of 15 Wang et al. J Mater Inf 2023;3:3 https://dx.doi.org/10.20517/jmi.2022.45

Figure 8. SrSO threshold diagrams in terms of the P(SO ) and temperatures for LSCF-6428 (red), LSCF-7328 (blue) and LSCF-8228
4
2
(green) under (A) dry air and (B) Argon.

Figure 9. SrSO threshold diagrams in terms of the P(SO ) and temperatures LSCF-6428 and LSM20 under air and argon conditions.
4 2

observed in the presence of 1, 10, and 100 ppm SO but not in 0.1ppm SO , and where sulfur poisoning was
2
2
[9]
more pronounced at lower temperatures. In addition, Wang et al. investigated the effect of Sr
concentration on the sulfur poisoning of LSCF by mainly using LSCF-6428 and LSCF-8228. Their results
showed that the thickness of SrSO formed in LSCF-6428 was almost four times thicker than that in LSCF-
4
8228, which has the lower relative Sr composition of the two LSCF materials.
Under typical P(SO ) atmospheric conditions, the only sulfur-containing secondary phase observed to form
2
in LSCF cathodes is SrSO 4 [6-12,30,31] . It is widely accepted that the formation of SrSO is responsible for the
4
long-term degradation of the LSCF cathode materials . Based on the simulation results in Figure 8, the
[5]
threshold for SrSO formation in LSCF-6428 at 800 °C is around 10 atm in air and 10 atm under reducing
-8
-10
4
conditions. The typical (SO ) content in the ambient air is at the level of 10 atm, indicating that ambient
-7
2
SO in the air is sufficient to drive long-term degradation of the LSCF-6428 cathode. Therefore, sulfur
2
poisoning results from accelerated testing, which is done at elevated SO levels, should mimic the natural
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sulfur poisoning that occurs during cathode operation at standard testing conditions with atmospheric SO ,
2
as in both cases, there is excess SO . Thus, accelerated testing will not only reduce the total time for running
2
poisoning experiments but is also capable of reproducing the sulfur poisoning phenomena that occur in the
presence of ambient SO during standard testing conditions. In systems where the CALPHAD simulations
2