Preparation And Performance Of Solid Oxide Fuel Cell BaCeO₃-based Electrolyte

As a new type of energy conversion device,solid oxide fuel cell?SOFC?has attracted great attention due to its high conversion efficiency,low environmental pollution and low cost.With the continuous research and exploration of related topics,SOFC has been continuously developed,but at the same time it also faces some problems,such as the traditional solid oxide fuel cell operating temperature is too high?800°C-1000°C?,reducing the battery service life.However,the proton-type solid oxide fuel cell?P-SOFC?has an operating temperature of only 400°C to 700°C,which is a good solution to this problem.As the core component of the battery,electrolyte is a research hotspot.At present,the main electrolyte materials studied include perovskite type oxide,layered perovskite type,pyrochlore structure and citrate structure.Among them,the perovskite oxide type electrolyte has BaCeO₃ group and BaZrO₃ based oxide,etc.The BaCeO₃ based electrolytes have attracted attention because of their good electrical conductivity and sintering properties.In this paper,BaCeO₃-based co-doped electrolyte materials are mainly studied.Three different elements of Bi,Sr and Sm are doped at the A and B sites of BaCeO₃perovskite structural electrolyte materials to improve their sintering properties,chemical stability and proton performance.Ba_0.6Sr_0.4Ce_1-xBi_x O_3-??BSCB-x,x=0,0.05,0.1,0.15,0.2?,Ba_0.6Sr_0.4Ce_0.9-y.9-y Bi_0.1Sm_y O_3-??BSCBS-y,y=0,0.05,0.1,0.15,0.2?and Ba_1-z-z Sr_z Ce_0.8Bi_0.1Sm_0.1O_3-??BSCBS-z,z=0,0.1,0.2,0.3,0.4,0.5?codped miscellaneous electrolyte material was prepared by citric acid combustion method.In addition,a BSCBS-y co-doped electrolyte was prepared by sol-gel method.XRD,SEM,chemical stability and conductivity analysis were carried out to study the effects of the doping of A and B sites of BaCeO₃-based electrolyte on the microstructure,chemical stability and proton performance of co-doped electrolyte materials.The results of BSCB-x electrolyte show that Sr,Bi co-doped perovskite structural electrolyte materials with impurity-free peaks can be prepared by citric acid combustion.By doping Sr and Bi respectively to the A and B sites of BaCeO₃,the sintering performance can be significantly improved.With the increase of Bi doping amount,the grain size of BSCB-x electrolyte increases,and the proton conductivity increases with the amount of Bi doping.When x=0.2,the proton conductivity is the largest,reaching1.054×10^-2S/cm.In addition,as the electrolyte sintering temperature increases,the proton conductivity of the co-doped electrolyte BSCB-0.1 increases with increasing temperature.When the burning temperature is 1150?,the proton conductivity reaches 4.94×10^-3S/cm.The chemical stability of BSCB-x electrolyte in boiling water and pure CO₂ was also studied.The results show that the undoped Bi element has poor electrolyte stability,while the Sr and Bi co-doped electrolytes are relatively stable.On the basis of studying the co-doped electrolyte BSCB-x,the B-site of the perovskite structure electrolyte BaCeO₃ was simultaneously doped with Bi and Sm elements to prepare the electrolyte BSCBS-y.In this experiment,the electrolyte BSCBS-y was prepared by citric acid combustion method and sol-gel method.The results show that both the citric acid combustion method and the sol-gel method can produce the electrolyte BSCBS-y without impurity peaks.The materials prepared by the two methods have good chemical stability in boiling water and pure CO₂,and both have good sintering properties.When preparing materials by citric acid combustion method,it is necessary to obtain an electrolyte material of perovskite structure above 900°C,and a dense electrolyte sheet can be sintered at 1250°C,and the proton conductivity gradually increases with the increase of Sm content.When y=0.2,the highest conductivity?at700??reach 2.17×10^-2S/cm.When the material is prepared by the sol-gel method,it is necessary to obtain a perovskite-type electrolyte material at 800?or higher,and a dense structure electrolyte sheet can be obtained by sintering at 1150?.The conductivity also increases with the increase of Sm doping amount.When y=0.2,the conductivity is the highest?700??,reaching 2.17×10^-3S/cm.When the temperature of the sintered electrolyte sheet is 1350?,the conductivity of the electrolyte BSCBS-0.1 reaches3.76×10^-3S/cm?at 700??,Which is higher than that(1.75×10^-3S/cm,at 700?).The results of BSCBS-z electrolyte show that Sr,Bi and Sm doped perovskite structural electrolyte materials without impurity peaks can be prepared by citric acid combustion method.By doping Sr,Bi and Sm in the A and B sites of BaCeO₃,the sintering performance can be significantly improved.With the increase of Sr content,the grain size of electrolyte BSCBS-z increases,and the proton conductivity shows a law of increasing first and then decreasing,When y=0.4,the conductivity is the highest?at700??,reaching 3.12×10^-3S/cm.The chemical stability of BSCBS-z electrolyte in boiling water and pure CO₂ was also studied.The results show that the electrolyte with undoped Sr element has poor stability in H₂O,while the electrolytes co-doped with Sr,Bi and Sm have good chemical stability.