Study On Preparation And Performance Of The BaCe_0.8Sm_xY_0.2-xO_3-δ-based Proton-conducting Electrolyte

In order to overcome the limitations of the traditional ionic conducting electrolyte of solid oxide fuel cells (SOFC) in high temperature, the paper was focused on protonic conducting electrolyte and composite electrolyte materials for intermediate temperature SOFC. The properties of these materials were examined by various methods to select proper candidates for SOFC and test their electrochemical properties.Sol-gel method was employed to synthesize BaCe0.8SmxY0.2-xO3-δ (x=0,0.05,0.1,0.15, 0.2). The structure and electrical properties of them were characterized by XRD and A.C. impedance, respectively. The results showed that doped BaCeO3 had pervoskite structure similar to pure BaCeO3. The conductivities of BaCe0.8Sm0.1Y0.1O3-δ were highest in wet hydrogen and air. Electrochemical performance of single cells was studied with configuration of Ni-BaCe0.8SmxY0.2-xO3-δ/BaCe0.8SmxY0.2-xO3-δ/Sm0.5Sr0.5CoO3-δ (SSC), in 5%H2(95% N2). At 550℃, the maximum power densities were 118mW/cm2、220mW/cm2 and 65mW/cm2, respectively.BaCe0.8Sm0.1Y0.1O3-δ(BCSY) was synthesized by sol-gel method and the anode-supporting cell Ni-BCSY/BCSY/SSC was assembled using BCSY as electrolyte. The properties of cells were characterized by XRD, SEM and electrochemical tests. The influence on SOFC of thickness and sintering temperature of cathode was studied, simultaneously. The electrolyte exhibited good chemical compatibility with SSC. At the same temperature, the open cirut voltage of cell with two coats cathode was 0.82V, which was better than others. When the sintering temperature achieved 1050℃, the current and voltage were highest. Under the optimum condition, the maximum power density of SOFC was 220mW/cm2 at 600 ℃.Composite electrolyte (BCSY)x-(SDC)1-x(x=0.2,0.5,0.8) was synthesized by sol-gel method. The sinter ability and chemical stability were characterized by XRD, SEM and XPS, respectively. The results indicated that (BCSY)0.5-(SDC)0.5 pellet was dense and maintained good chemical stability after boiling in water and reduction, by the way, the conductivities were highest in the air and hydrogen. Then it was chosen as electrolyte for SOFC. The cell of Ni-B5S5/B5S5/SSC achieved the maximum voltage of 0.96V and the maximum power density of 240m W·cm-2.