A comparative study of Sm0.5Sr0.5MO3-？(M=Co and Mn) as oxygen reduction electrodes of solid oxide fuel cells

Abstract: Sm0.5Sr0.5MO3-？(M=Co and Mn) materials were synthesized and their properties and performance as cathodes of solid-oxide fuel cells (SOFCs) on Sm0.2Ce0.8O1.9 (SDC) and Y0.16Zr0.92O2.08 (YSZ) electrolytes were comparatively studied. The phase structure, thermal expansion behavior, oxygen mobility, oxygen vacancy concentration and electrical conductivity of the oxides was systematically investigated by XRD, dilatometer, O2-TPD, iodometric titration and four-probe DC conductivity, respectively. Sm0.5Sr0.5CoO3-？(SSC) shows much larger oxygen vacancy concentration, electrical conductivity and TECs than Sm0.5Sr0.5MnO3-？(SSM). Powder reaction demonstrated SSM has much better chemical compatibility with the YSZ electrolyte than SSC, while both of them have good compatibility with SDC electrolyte. EIS results indicate the performance of SSC and SSM electrodes is highly dependent on the electrolyte they are deposited on. SSC is suitable for SDC electrolyte while SSM prefers the YSZ electrolyte. A peak power density as high as ~ 690 mW cm＆#8722;2 at 600 oC was achieved for a SOFC with thin-film SDC electrolyte and SSC cathode, while a similar cell with YSZ electrolyte shows very poor performance. On the other hand, SSM performs better on YSZ electrolyte, and a fuel cell with SSM cathode and thin-film YSZ electrolyte delivered a peak power density of ~590 mW cm＆#8722;2 at 800 oC.

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