电动势法测量混合氧离子—电子导电氧化物离子迁移数的理论研究  

Theoretical Study on the Ionic Transport Numbers of the Mixed Oxygen Ionic-electronic Conducting Oxides Measured with EMF Method

作　　者：黄悦 莫滢钰 练文超 邱瑞铭 刘建平 雷励斌 HUANG Yue;MO Yingyu;LIAN Wenchao;QIU Ruiming;LIU Jianping;LEI Libin(School of Materials and Energy,Guangdong University of Technology,Guangzhou 510006,Guangdong,China)

机构地区：[1]广东工业大学材料与能源学院,广东广州510006

出　　处：《陶瓷学报》2022年第5期926-933,共8页Journal of Ceramics

基　　金：国家自然科学基金(52002082)。

摘　　要：混合氧离子-电子导电氧化物材料在固体氧化物燃料电池(SOFCs)/电解池(SOECs)中有广泛应用,准确测量其离子迁移数对其应用和性能优化具有重要意义。电动势(EMF)法是最常用的测量离子迁移数的方法之一,但其测量值仅为材料的表观离子迁移数t_(i)^(app)。以CeO_(2)基电解质材料为研究对象,通过建立缺陷分布模型研究了CeO_(2)基电解质膜内离子迁移数的分布情况和不同测试条件对EMF方法测得的t_(i)^(app)的影响,依此判断EMF方法的准确性。研究结果表明:离子迁移数在电解质膜内分布不均匀;在电解质膜较薄时,t_(i)^(app)受电解质膜厚度的影响较大;电解质膜两侧存在较大氧化学势梯度时(P_(O_(2))^(high)/p_(O_(2))^(low)>10^(25)),t_(i)^(app)总体上倾向于电解质在高氧分压侧的离子迁移数,并且随温度的升高和材料电子电导率系数的增大而减小;电解质膜两侧均为还原气氛时(Po_(2)>10^(-20)atm),通过EMF方法测出的t_(i)^(app)倾向于电解质在低氧分压侧的离子迁移数;当电解质膜两侧氧分压都较大时(Po_(2)>10^(-15)atm).,t_(i)^(app)主要反映出电解质在高氧分压侧的离子迁移数。The mixed oxygen ionic-electronic conducting oxides have been widely used in the fields of solid oxide fuel cells(SOFCs)and solid oxide electrolysis cells(SOECs).The accurate measurement of ionic transport numbers in the mixed oxygen ionic-electronic conducting oxides is significant for their performance optimization and application.Electromotive force(EMF)method is one of the most widely used approaches to measure the ionic transport numbers.However,the measured result of EMF method is the apparent ionic transport number t_(i)^(app).CeO_(2)-based electrolyte was selected as an object,while a model of defect distribution was established.With this model,the distribution of ionic transport numbers across the CeO_(2)-based electrolyte membrane was analyzed and the effect of test conditions on t_(i)^(app) was examined by using the EMF method,thus evaluating the accuracy of the EMF method.It is demonstrated that the ionic transport number is inhomogeneous across the electrolyte membrane.t_(i)^(app) is significantly dependent on thickness of the electrolyte membrane when the electrolyte membrane is relatively thin.When there is a large gradient of oxygen chemical potential on both sides of the electrolyte membrane (P_(O_(2))^(high)/p_(O_(2))^(low)>10^(25)),t_(i)^(app) tends to be ionic transport number of the electrolyte layer at high 2 OP side and decreases with increasing temperature and the electronic conductivity coefficient of the electrolyte.t_(i)^(app) tends to be ionic transport number of the electrolyte layer at the low Po_(2) side when the two sides of the electrolyte layer are in reducing atmospheres(Po_(2)>10^(-20)atm).t_(i)^(app) mainly reflects the ionic transport number of the electrolyte layer at the high 2 OP side,when 2 OP on the two sides of the electrolyte layer are large(Po_(2)>10^(-15)atm).

关 键 词：电动势法 固体氧化物燃料电池 缺陷分布模型 混合氧离子—电子导电氧化物 离子迁移数 

分 类 号：TQ174.75[化学工程—陶瓷工业]