Properties Of Sr₂Fe_1-xMg_xMoO_6-δ Double Perovskite Anode Materials

As the increasing economy of the world, the demand for energy is getting moreand more urgent for each country in the world. Every country in the world aresearching for new kind of energy to insure the sustainable development. The solidoxide fuel cell (SOFC) is an environmental friendly energy generator with highefficiency. SOFC is the fourth generation of fuel cell, and it has the advantage of lowpollution to the environment, high efficiency, high flexibility, wide sources and highsafety, so it get much attention in recently years. Conventional anode consist ofNi-based material, but it has many defects, such as carbon deposition and sulfurpoisoning, and both of the defects can affect the performance of the cell. Therefore,developing a new kind of anode material with high performance is important for thecommercial use of SOFC.In this paper, new perovskite materials Sr2Fe1-xMgxMoO6-δ(x=0.2,0.4,0.6,0.8)were synthesized by the solid-state method and investigated as anode materials forIT-SOFCs under hydrogen atmosphere.The conductivity of Sr2Fe1-xMgxMoO6-δdecreases with the increasing of Mgdoped, the reason is that the electronic state of Fe2+-Mo6+and Fe3+-Mo5+degenerate.TG-DTA results show that the Sr2Fe1-xMgxMoO6-δsamples have a slight weight lossor weight gain phenomenon within the scope of the measuring temperature. it ismainly due to the residual water and carbon dioxide of the Sr2Fe1-xMgxMoO6-δwhichis caused by the volatilization and decomposition. And the Sr2Fe1-xMgxMoO6-δsamples appear wide exothermic peak in the DTA curve. Thermal expansionresearch result indicates that the average thermal expansion coefficient of the sampleof x=0.2is15.5x10-6K-1range from30to520oC.The average thermal expansioncoefficient of the samples of x=0.4and x=0.6is16.4x10-6K-1and15.0x10-6K-1range from30to720oC. Within the different temperature range, the sample of x=0.2, x=0.4and0.6for thermal expansion coefficients is close to the thermal expansioncoefficient of LSGM electrolyte material. And with the increasing of Mg ion dopingamount, the impedance of the sample value is more and more big, the minimumimpedance of the sample of x=0.2is0.45cm2at850oC. The performance of thesingle battery decreases with the increasing of Mg ions doped, the single cell of x=0.2which is considered as anode shows the best electrochemical performance inhydrogen gas, the maximum power density of the single battery can reach150.8mWcm-2at850oC.