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Page 10 of 27 Chen et al. Energy Mater. 2025, 5, 500045 https://dx.doi.org/10.20517/energymater.2024.144

significantly with increasing temperature, suggesting the potential of LCM as an anode material for SOECs.

3+
3+
3+
In addition to LSM, B-site transition metal ion (Fe , Co , and Ni )-doped perovskites have also been
demonstrated to enhance the oxygen vacancy concentration. Among them, Co and Fe co-doped
La Sr Co Fe O has been the subject of considerable research interest due to its stability and catalytic
1-y
y
x
1-x
3-δ
activity in OER. A discontinuous Sr layer was formed between LSCF and YSZ during anode polarization.
This inhibited the segregation of Sr and the movement toward the electrode/electrolyte interface, resulting
in the formation of a stable electrode/electrolyte layer. This greatly improves the performance of SOECs.
Furthermore, doping other metal elements has also been demonstrated to enhance the performance of
LSCF-based oxygen electrodes. Tian et al. synthesized PrBa Sr Co Fe O (PBSCF) double-perovskite by
5+δ
0.5
0.5
0.5
1.5
[69]
wet-chemical method, and then electrolyzed at 850 °C, 2.0 V, and 70 vol% absolute humidity . Results
-1
-2
showed a hydrogen production rate of up to 1,544 mL·cm ·h , with a maximum current density of
3.694 A·cm . Additionally, the material demonstrated high stability, as shown in Figure 5E. Among them,
-2
the excellent performance of PBSCF under polarized conditions may be due to its high intrinsic catalytic
activity, which proves that SOECs based on this type of material have a wide range of applications.
Ruddlesden-Popper (R-P)-phase perovskites have the structure A B O . As shown in Figure 5F, this type
3n+1
n+1 n
has an alternating structure of AO rock salt lattice and perovskites, and generally exhibits high oxygen
mobility and stability. The typical R-P-phase perovskites are Ln NiO (LNO) and Pr NiO (PNO)-based
2
2
4+δ
4+δ
materials, which can accommodate more oxygen, have lower polarization resistance, and exhibit excellent
oxygen transport properties. Additionally, they are free of Sr and Co, which can avoid being poisoned by
cobalt in the reactant gas and have good chemical stability . In order to gain insight into the mechanism of
[70]
oxygen transport in R-P perovskites, Gu et al. conducted an in-depth analysis of 20 samples comprising six
distinct R-P perovskites, such as La NiO , La CoO , etc. . Their findings revealed that the OER during the
[71]
4
2
4
2
anodic electrolysis process is influenced by three key factors: the interstitial oxygen ion concentration, the
migration of interstitial oxygen ions, and the migration of lattice oxygen. Therefore, they believe that the
doping of metal ions in a reasonable quantity can be employed to enhance the material properties and
accelerate the reaction rate. Therefore, future research should focus on the optimization of such materials
and the study of reaction mechanisms.
At present, the majority of SOEC anodes are perovskites containing Sr and Co, which face the problems of
Sr segregation and Co poisoning. Consequently, Co- and Sr-free R-P perovskites have been gradually
gaining prominence, yet their utilization in SOECs has durability challenges. Consequently, experimental
confirmation of the crystal structure and physicochemical attributes of the samples remains a necessity.
Hence, the current research should focus on understanding the reaction mechanism, optimizing electrode
properties, developing new materials or improving existing ones, and making a reasonable choice between
catalytic activity and stability. Table 4 provides a brief summary of the anode materials and their electrolytic
cell properties from selected studies on SOEC anodes in recent years. It can be seen that elemental doping is
still the main means to improve the performance of anode materials.
Microstructure modification
In addition to the design of new materials, the appropriate adjustment of the microstructure of existing
materials is also a useful approach to improving the performance of materials. By precisely adjusting the
microstructure (i.e., porosity, pore size, and distribution), the area of TPBs can be increased to ensure
sufficient active surface area during the reaction, which can reduce polarization loss. Nevertheless, the
porosity must be constrained to a specific range, as excessive porosity will impair the stability of the
electrodes and diminish the TPB area .
[91]