Study On Chromium Poisoning Resistance Of Lanthanum Strontium Colbalt Ferrite Cathode In Solid Oxide Fuel Cells

As a new type of energy conversion device with high energy conversion efficiency and environmental friendliness,solid oxide fuel cell（SOFC）has attracted widespread attention.La_0.8Sr_0.2Co_0.2Fe_0.8O_3-δ（LSCF）has become one of the most popular cathode materials in SOFC due to its excellent ion-electron mixing conductivity and thermal expansion coefficient to match with other components.However,the chromium in the SOFC connector would become a gaseous compound at working temperature and enter the cathode,causing the chromium poisoning of the cathode.This would result in the deterioration in the electrochemical performance of the cathode and seriously affect the long-term efficient operation of the SOFC.In order to study the chromium poisoning behavior of the chromium element in the connector to the LSCF cathode,explore the chromium poisoning resistance strategy,the granular and fibrous LSCF cathode material was prepared by the sol-gel method and the electrospinning.Ferritic stainless steel（SUS）410 and 430 are chromium sources.The polarization voltage,polarization resistance and chromium deposition changes of the cathode before and after chromium poisoning are compared,and the degree of poisoning of the two cathodes by the two chromium sources is studied.The results show that SUS410 has a stronger chromium poisoning effect on the LSCF cathode,and chromium poisoning has a greater effect on the fiber LSCF cathode.In order to improve the chromium poisoning resistance of the LSCF cathode,cerium nitrate and gadolinium nitrate solution were impregnated on the cathode.After sintering,gadolinium oxide doped cerium oxide（GDC）was formed.The impregnation mass ratio was LSCF:GDC=1:0.2,and the sintering temperature was 850℃.The results show that impregnation of GDC can improve the stability and electrochemical performance of the LSCF cathode,as well as reduce the influence of chromium poisoning on the cathode.After being immersed in GDC,the polarization resistance of the granular LSCF cathode at 750℃decreased by 54.2%.After using SUS410connector as the chromium source for 120 h,the polarization voltage undergoes a variation trend from increase to decrease,and the increase in polarization resistance at750℃decreased by 85.7%.The value of the molar amount of Sr in the SrCrO4 on the cathode in the total molar amount of Sr decreased by 3.31%.Based on the research results of the GDC oxygen ion conductor on the chromium resistance performance of LSCF,the LSCF cathode was further impregnated with barium acetate,nickel nitrate,and iron nitrate solutions.After sintering,a mixed phase of barium carbonate,nickel oxide,and barium ferrite was formed（BNF）,the impregnation mass ratio was LSCF:BNF=1:0.1,and the sintering temperature was900℃.The results show that immersion in BNF can not only improve the electrochemical performance of the LSCF cathode,but also reduce the amount of chromium deposited in the cathode area.After being immersed in BNF,the polarization resistance of the granular LSCF cathode at 750℃decreased by 65.3%.The increase in polarization voltage decreased by 61.2%after the SUS410 connector was used as the chromium source for 120 h,and the increase in polarization resistance at 750℃decreased.At 58.4%,the value of the molar amount of Sr in the SrCrO₄on the cathode in the total molar amount of Sr decreased by 6.25%,and the molar ratio of Cr/Co on the cathode decreased by 21.9%.