SrCe(0.9)Sm(0.1)O(3-α) Compounded with NaCl-KCl as a Composite Electrolyte for Intermediate Temperature Fuel Cell.

SrCeO₃ and SrCe(0.9)Sm(0.1)O(3-α) were synthesized using a high-temperature solid-state reaction method using Sm₂O₃, SrCO₃, CeO₂ as precursors, then the SrCe(0.9)Sm(0.1)O(3-α)-NaCl-KCl composite electrolyte was fabricated by compounding SrCe(0.9)Sm(0.1)O(3-α) with NaCl-KCl and sintering it at a lower temperature (750 °C) than that of a single SrCeO₃ material (1540 °C). The phase and microstructure of the samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The conductivities of the samples were measured in dry nitrogen atmosphere using electrochemical analyzer. The conductivities of the SrCeO₃, SrCe(0.9)Sm(0.1)O(3-α) and SrCe(0.9)Sm(0.1)O(3-α)-NaCl-KCl at 700 °C were 2.09 × 10(-5) S·cm(-1), 1.82 × 10(-3) S·cm(-1) and 1.43 × 10(-1) S·cm(-1) respectively. The conductivities of SrCe(0.9)Sm(0.1)O(3-α)-NaCl-KCl composite electrolyte are four orders of magnitude higher than those of SrCeO₃ and two orders of magnitude higher than those of SrCe(0.9)Sm(0.1)O(3-α). The result of logσ ~ logpO₂ plot indicates that SrCe(0.9)Sm(0.1)O(3-α)-NaCl-KCl is almost a pure ionic conductor. The electrolyte resistance and the polarization resistance of the H₂/O₂ fuel cell based on SrCe(0.9)Sm(0.1)O(3-α)-NaCl-KCl composite electrolyte under open-circuit condition were 1.0 Ω·cm² and 0.2 Ω·cm² respectively. Further, the obtained maximum power density at 700 °C was 182 mW·cm(-2).