Study On The Cr Poisoning At The Oxygen Electrodes And The Preparation Of Anti-Cr Poisoning Materials

Performance degradation of oxygen electrode is one of main reasons that does Performance stability of cells decreased on SOEC/SOFC.Improve the stability of oxygen electrode can effectively increase the electric reactor operating life which is of great significance.The widely adopted oxygen/cathode electrode is ABO₃perovskite oxide structure,in which the perovskite structure,B-site of ABO₃perovskite oxide structure is mainly occupied by transition metal（TM）.The research on(La_0.6Sr_0.4)XO₃（X=Mn,Fe,Co）oxygen electrodes of SOECs to unfold the effect of the B-site transition metals（TMs）indicate that the type of the transition metal have a significant influence for the oxygen electrode oxygen vacancy concentration,electronic and ionic conduction,thermal expansion coefficient,electrochemical catalytic activity and other properties of the material.Moreover our research shows that partial substitution of B-site cations with niobium will significantly improve the stability of ABO₃ perovskite and the anti-Cr poisoning performance electrode materials,Nb doping enhances thevalence stability of cobalt and reduction in Srsegregation.The reasons of performance degradation of the electrode in the SOEC are consistent with in the SOFC,which is an alkaline earth metal react with atmosphere of impurities on surface under a high temperature.This paper main contents and results are as follows:（1）A comparative study was conducted on the widely adopted(La_0.6Sr_0.4)XO₃（X=Mn,Fe,Co）oxygen electrodes of SOECs to unfold the effect of the B-site transition metals（TMs）on the activities,activation effects and degradations of the perovskite electrodes.Activities of the electrodes towards OERs were closely related to the B-site TMs.Performance of the electrodes followed the order of LSC>LSF>LSM.The significant differenceinthe electrochemical performance was attributed to the variant oxygen ionic conductivities arising from the different degrees of hybridization that led to different oxygen vacancy formation energies.Stability of the(La_0.6Sr_0.4)XO₃（X=Mn,Fe,Co）in the Cr-containing atmosphere varied significantly with the B-site TMs,following the order of LSF>LSC>LSM.（2）A study was conducted on the performance degradation problems and mechanisms perovskite structure stability of(La_0.6Sr_0.4)(Co_0.2Fe_8-xNb_x)O_3-δ（x=0,0.04,0.08and 0.12）cathode prepared by the solid-state reaction method and molten salt method.Explored the optimum synthesis of Nb-doped LSCFN cathode materials andprepared the material of anti-Cr deposition and poisoning.Performance of the electrodes prepared by solid phase reaction followed the order ofLSCFN（x=0.04）>LSCFN（x=0.08）>LSCFN（x=0.12）>LSCFN（x=0）.Analyzing the electrochemical results and SEM microstructure analysis,the catalytic activity and the characteristics of anti-Cr deposition and poisoning of samples prepared by molten salt followed the order of LSCFN（x=0.04）>LSCFN（x=0.08）>LSCFN（x=0.12）>LSCFN（x=0）.