Effect of Ce0.8Sm0.2O1.9 interlayer on the electrochemical performance of La0.75Sr0.25Cr0.5Mn0.5O3−δ–Ce0.8Sm0.2O1.9 composite anodes for intermediate-temperature solid oxide fuel cells

• Alternative anodes of LSCM–SDC were prepared and investigated for IT-SOFCs.
• Compositions of LSCM–SDC composite anodes were optimized.
• SDC interlayer was effective for improving the performance of LSCM–SDC anodes.
• Outstanding intermediate-temperature electrochemical performance was achieved.

Composite anodes of La0.75Sr0.25Cr0.5Mn0.5O3−δ–Ce0.8Sm0.2O1.9 (LSCM–SDC) were prepared and investigated as anode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs) with YSZ electrolyte. Results showed that the addition of SDC significantly enhanced the electrochemical performance of LSCM anode. The anode containing 40 wt.% SDC demonstrated optimal performance. The polarization resistance and anodic overpotential (at a current density of 0.05 A cm−2) of this anode were 0.95 Ω cm2 and 0.12 V in H2 at 800 °C, respectively, whereas those of pure LSCM anode were 3.66 Ω cm2 and 0.38 V, respectively. The electrochemical performance of the LSCM–40SDC composite anode was further improved when a thin SDC interlayer was coated between the anode and YSZ electrolyte. The resulting polarization resistance and anodic overpotential with the SDC interlayer were 0.30 Ω cm2 and 0.035 V in H2 at 800 °C, demonstrating a reduction by factors of 3.2 and 3.4, respectively. The impedance data displayed that the coated SDC interlayer mainly affected the low frequency electrode process, indicating that the SDC interlayer played an important role in the promotion of the dissociation and diffusion processes of H2 oxidation reaction.