Preparation And Properties Of R-P Type Layered Perovskite Symmetrical Electrode

Solid oxide fuel cells?SOFCs?can directly convert chemical energy of many fuels into electrical energy,which have the advantages of high efficiency and cleanliness.However,the production process of traditional SOFC is complex and expensive,with the occurrence of carbon deposition and sulfur poisoning at anode using hydrocarbon fuels.Using the same material as the cathode and anode to simplify the manufacturing process and reduce costs,symmetrical solid oxide fuel cells?SSOFCs?have been researched extensively.Meanwhile,cells in this structure can solve the problems of carbon deposition and sulfur poisoning by exchanging gas paths.In this article,the R-P type layered perovskite structures of symmetrical electrodes in different dimensions have been researched,through the method of doping and recombination.The XRD analysis of phase,XPS analysis of powder,chemical compatibility test,thermal expansion coefficient characterization,electrical conductivity and stability under redox atmosphere were tested as well.The R-P type electrode?A₃B₂O₇?La_0.25Sr_2.75Fe₂O_7-??LSFO₇?electrode powder was prepared through the citric acid-EDTA synthesis method.The electrode LSFO₇possesses outstanding chemical compatibility with GDC and displays excellent electrical conductivity under redox atmosphere.The maximum value of electrical conductivity was 71.36 S/cm in air atmosphere and the maximum value of electrical conductivity was 0.067 S/cm in H₂ atmosphere.In the power test of the symmetrical single cell of LSFO₇|GDC|YSZ|GDC|LSFO₇,the maximum power density of226.68 mW/cm² was obtained at 800?,and the corresponding polarization impedance was 1.13??cm².In the analysis of microstructure,each component was closely connected,and there was no phenomenon of peeling or separation,which indicates that the cell exhibited good operating stability.The higher dimension R-P type(A₄B₃O₁₀)LaSr₃Fe_3-xCo_xO_10-??x=0,1,1.5?materials also exhibit stable redox reversibility.Meanwhile,the maximum conductivity values of LaSr₃Fe₂CoO_10-?(LSFCO₁₀)were 224.58 S/cm and 0.021 S/cm in air and H₂atmosphere,respectively.The symmetrical single cell of LSFCO₁₀|GDC|YSZ|GDC|LSFCO₁₀ was tested.The maximum power density of 351.4 mW/cm² was obtained at800?,and the corresponding polarization impedance was 0.2552??cm².Then the result of long-term test indicates that the SSOFC exhibits good long-term working stability.The maximum conductivity value of composite electrode LSFO₇-GDC was 20.33S/cm in air atmosphere,and the addition of electrolyte GDC hindered the passage of electron to decrease the electronic conductivity compared with single electrode LSFO₇.On the contrary,the reduction of Ce⁴⁺increased the electronic conductivity to enhance conductivity under H₂ atmosphere,and the maximum conductivity value was 0.6933S/cm.During the power measurement of symmetrical single cell LSFO₇-GDC|GDC|YSZ|GDC|LSFO₇-GDC,the power density of 336.14 mW/cm² was obtained at 800?,and the corresponding polarization impedance was 0.3958??cm².The long-term test of100 h shows that SSOFC exhibits good working stability.In conclusion,the combination of GDC can greatly increase its three-phase reaction interface,accelerate the rate of oxygen transmission and oxygen reduction,reduce the interface polarization resistance,and improve the output performance of cell.