Preliminary studies of the new Ce-doped La/Sr chromo-manganite series as potential SOFC anode or SOEC cathode materials

CeLSCM (CexLa0.75 − xSr0.25Cr0.5Mn0.5O3) materials were synthesized for x = 0, 0.10, 0.25 and 0.375. Structural, physico-chemical and electrical properties are compared to La0.75Sr0.25Cr0.5Mn0.5O3 (LSCM). For x ≤ 0.25, these oxides exhibit a rhombohedral symmetry (space group R3¯c), whereas the structure is cubic (Pm–¯3–¯3m) for x = 0.375. All those materials are stable in both elaboration and operating conditions of an SOFC anode. They are also stable in steam electrolysis (SOEC) cathodic conditions. Exposure to air yields the formation of CeO2 for cerium containing materials, and decomposition into a Ruddlesden Popper phase type chromo-manganite occurs in dry H2 both for CeLSCM series and pure LSCM. In dry argon, wet argon and wet hydrogen, these materials are p-type semi-conductors. Electrical conductivity increases with cerium content in argon and reaches 35 S·cm− 1 at 900 °C. In wet hydrogen (H2-3% H2O), the total conductivity is about 1 S·cm− 1 at 900 °C, regardless the cerium content, which is regarded as not so detrimental for the application.

Research highlights
► Lanthanum in the mixed conductor perovskite oxide LSCM was substituted by cerium.
► Materials are stable in SOFC anodic and SOEC cathodic conditions.
► Materials are p-type semi-conductors.
► Cerium substitution improves the electrical conductivity in argon.
► In H2-H2O the conductivity is ~ 1 S·cm− 1 at 900 °C, regardless the cerium content.