Study On Electrode Of SrFeO_3-? Perovskite Oxide For The Regulation Of Defect And Steam Electrolysis

Solid oxide electrolysis cell(SOEC)is an electrochemical energy conversion device,through which electrical energy can be converted into chemical energy.As the same time,electricity and heat are combined for the electrochemical reduction of gas.This is the reverse process of solid oxide fuel cell(SOFC).In this paper,the cathode materials of SOEC are studied.Conventional Ni-YSZ cathode has been used in SOEC for gas electrolysis and exhibited excellent performance in high temperature.However,Ni-YSZ cathode is easy to suffer from oxidation that leads to performance degradation,which strongly limits its application.In contrast to Ni-YSZ,the perovskite-type solid oxide(ABO3-6)performs well in the mixed ionic and electronic conductivity and costs lower,which has attracted a lot of attention in the field of high-temperature solid oxide electrolysis cell.In this paper,the Sr0.9Fe0.9Zr0.1O3-?,Sr1-xPrxFeO3-?(x=0.02,0.04,0.06,0.08,0.10)and Sr0.95FeO3-? powders were prepared by solid state synthesis.The X-ray diffraction(XRD)was used to identify the phase of strontium ferrite.Thermogravimetry was used to record the weight change versus temperature.The morphology of the samples and the cross section of single electrolysis cell were observed by scanning electron microscopy(SEM).And the conductivity of sample was measured.Then,these strontium ferrite oxides were made into cathode slurry.The polarization resistance of symmetrical cell was investigated.In addition,polarization resistance,?-? curves and short-term performance and so on were investigated as well.Finally,the exhaust gas discharged from the cathode was collected and analyzed by gas chromatography.The hydrogen yield and the Faradaic efficiency of SOEC were investigated.The experiments show that the conductivities of Sr0.9Fe0.9Zr0.1O3-?,Sr0.96Pr0.04FeO3-?and Sr0.95FeO3-? under 5%H2/Ar at 800 ? are all greater than 1 S cm-1,which fully satisfy the requirements of SOEC cathode materials.Moreover,their polarization resistance under hydrogen partial pressure is small enough,less than 0.3 ? cm2 in pure hydrogen atmosphere.When used as cathode for steam electrolysis,The current efficiency of Sr0.9Fe0.9Zr0.1O3-? is 80%.The maximum current efficiency of Sr0.96Pr0.04FeO3-? is 98%and the minimum is 95%.The current efficiency of Sr0.95FeO3-?is about 98%.all of above shows that the strontium ferrite oxide cathode is conducive to the improvement of the performance of SOEC and can be used in steam electrolysis.