Effect Of Halogen Doping On The Performance Of Cathode Material BaCe_0.1Co_0.3Fe_0.6O_3-?

At present,solid oxide fuel cells(SOFCs)as one of the main research directions in the field of energy,have attracted considerable attention due to their environmental friendliness,outstanding fuel flexibility and high energy conversion effectivity.Whereas,the current level of commercialization of SOFCs is not high,mainly due to the large polarization resistance of the cathode at lower operating temperatures.Consequently,the development of efficient cathode materials is a promising alternative method to facilitate the commercialization of SOFCs.Recently,the cathode material most commonly used for SOFCs are oxides with ABO3 perovskite lattice structures.In general,A and B sites doping is the most adopted strategy for improving the performance of such cathode materials.Herein,we demonstrate that halogen doping can enhance the properties of perovskite-type cathode materialsIn this paper,all cathode materials of BaCeO.iCo0.3Fe0.6O3-?(BCCF).BaCe0.1Co0.3Fe0.6O2.95-?Cl0.05(BCCFCl0.05),BaCe0.1Co0.3Fe0.6O2.95-?F0.05(BCCFF0.05),and BaCe0.iCo0.3Fe0.6O2.95-?F0.1(BCCFF0.1)were synthesized by combined EDTA-CA complexing sol-gel process.The formation of all single perovskite phases with cubic symmetry was demonstrated by X-ray powder diffraction(XRD)technology.In combination with energy-dispersive X-ray spectroscopy(EDS)mapping technology,we confirmed that halogens were successfully incorporated into the lattice of the BCCF perovskite oxide.Afterward for the above four kinds of cathode materials,scanning electron microscopy was used to characterize their particulate morphology.Four-probe method was utilized to investigate the electrical conductivity in air at temperatures between 300? and 750?.Oxygen temperature-programmed desorption(O2-TPD)was performed.Thermogravimetric(TG)analysis was given in N2 from 30? to 1000?.The thermal expansion data was gathered in air from room temperature to 1000? and X-ray photoelectron spectra(XRD)analysis.Then above four materials were used respectively as the cathode materials of proton-conducting solid oxide fuel cells(H-SOFCs)with BZCYYb as the electrolyte,the anode-supported single-cells Ni-BZCYYb | BZCYYb | BCCF(with electolyte 29.1 ?m in thickness),Ni-BZCYYb | BZCYYb | BCCFCl0.05(with electolyte 28.9 ?m in thickness),Ni-BZCYYb | BZCYYb | BCCFF0.05(with electolyte 29.5 ?m in thickness),and Ni-BZCYYb | BZCYYb | BCCFF0.1(with electolyte 29.8 ?m in thickness)were prepared by dry pressing method.At the same time,electrochemical performance of all anode-supported single-cells were studied.The results show that the output power densities of the above four single cells at 700? were 493.6,747,516.1,509.2 mW·cm-2,respectively.The polarization resistances were 0.066,0.036,0.039,and 0.046 ?·cm2,respectively.It can be seen from the above results that the halogen anions occupying oxygen sites could improve the electrochemical performance of the cathode material BCCF.This is consistent with the characteristics of the halogen doping to enhance the activity of the lattice oxygen and increase the oxygen vacancy concentration for the material.Therefore,halogen doping may provide a practical method for improve the performance of perovskite-type SOFCs cathode materials.