Sm_0.5Sr_0.5CoO₃-Sm_0.2Ce _0.8O_1.9 composite oxygen electrodes for solid oxide electrolysis cells

In this paper, a series of Sm_0.5Sr_0.5CoO ₃-Sm_0.2Ce_0.8O_1.9 (SSC-SDC) composite with different ratios were prepared and characterized as oxygen electrodes for solid oxide electrolysis cells (SOECs). Yttria-stabilized zirconia (YSZ) was selected as the electrolyte with a SDC barrier layer to avoid detrimental solid state interaction between SSC and YSZ. At 850 °C, the impedance spectra showed that the optimum SDC content in the composite electrode was found to be about 30 wt.%, which showed a much lower area specific resistance of 0.03 Ω cm². The electrochemical performances of a Ni-YSZ hydrogen electrode supported YSZ membrane SOEC with the SSC-SDC73 oxygen electrode were also measured at 750-850 °C. The hydrogen production rate calculated from the Faraday's law was 327 mL cm^-2 h^-1 at 850 °C at an electrolysis voltage of 1.3 V with a steam concentration of ∼40%, which indicated that the SSC-SDC73 was a promising oxygen electrode candidate for high temperature electrolysis cells.