A novel composite was synthesized by mixing La0.1Sr0.9MnO3-δ (LSM) with Ce0.8Sm0.2O2-δ (SDC) for the functional layer of low temperature solid oxide fuel cell (LT-SOFC). Though LSM, a highly electronic conducting semiconductor, was used in the functional layer, the fuel cell device could reach OCVs higher than 1.0 V without short-circuit problem. A typical diode or rectification effect was observed when an external electric force was supplied on the device under fuel cell atmosphere, which indicated the existence of a junction that prevented the device from short-circuit problem. The optimum ratio of LSM:SDC = 1:2 was found for the LT-SOFC to reach the highest power density of 742 mW·cm-2 under 550 °C The electrochemical impedance spectroscopy data highlighted that introducing LSM into SDC electrolyte layer not only decreased charge-transfer resistances from 0.66 Ω·cm² for SDC to 0.47⁻0.49 Ω·cm² for LSM-SDC composite, but also decreased the activation energy of ionic conduction from 0.55 to 0.20 eV.
Keywords: LSM (La0.1Sr0.9MnO3−δ); LT-SOFC; hetero-interface; junction; semiconductor-ionic nanocomposite.