Semiconductor-Ionic Nanocomposite La(0.1)Sr(0.9)MnO(3−δ)-Ce(0.8)Sm(0.2)O(2−δ) Functional Layer for High Performance Low Temperature SOFC

A novel composite was synthesized by mixing La(0.1)Sr(0.9)MnO(3−δ) (LSM) with Ce(0.8)Sm(0.2)O(2−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·cm(2) for SDC to 0.47–0.49 Ω·cm(2) for LSM-SDC composite, but also decreased the activation energy of ionic conduction from 0.55 to 0.20 eV.