固体氧化物燃料电池用CeO_(2)基电解质的研究进展

Research Progress of CeO_(2)-based Electrolytes for Solid Oxide Fuel Cells

作为一种高效的能源转换装置,固体氧化物燃料电池(SOFC)因具有高效率、环境友好和燃料灵活等优点受到广泛关注。电解质作为SOFC的核心部分,其性能的好坏直接决定SOFC的性能。SOFC使用的传统电解质材料是部分氧化钇稳定的氧化锆(YSZ),但因其工作温度高(约1000℃),由此带来电极材料的选择、密封等诸多困难。因此,开发适用于中低温下的电解质对推进SOFC的商业化进程至关重要。单元素掺杂的氧化铈基电解质在中低温下的电导率高于同温度下YSZ的电导率。然而,CeO_(2)基电解质也存在以下不足:在低氧分压下,部分Ce^(4+)被还原为Ce^(3+)而产生电子电导;在中低温度下,晶界电阻较大而使总电导率降低。影响CeO_(2)基电解质电导率的因素较多,如粉体的制备方法、烧结体的微观形貌、掺杂剂的种类和浓度。其中,较为重要的影响因素是掺杂剂的种类及其浓度、粉体的制备方法。针对以上问题,研究人员普遍认为,相比于单掺杂CeO_(2),元素共掺或多掺(尤其掺杂稀土元素)更有利于改善电解质的离子电导率,并降低电子电导率。掺杂元素的种类通常包括:稀土元素和部分碱土金属元素。除元素掺杂外,不同碳酸盐复合的CeO_(2)基电解质也引起了研究人员的兴趣。在制备方法上,采用微波烧结、多元醇法、静电纺丝等不同粉体制备方法可得到高离子电导率的电解质,此外,将电解质薄膜化或采用脉冲激光沉积(PLD)在CeO_(2)电解质基底上沉积一层隔膜都可以降低电子电导,提高电导率。本文结合最近几年学者们对CeO_(2)基电解质的研究状况,简述了元素掺杂、粉体的制备方法以及电解质薄膜对CeO_(2)基电解质电性能的影响,并对其发展进行了展望。

As a high-efficiency energy conversion device,solid oxide fuel cell(SOFC)has attracted widely attention due to its high efficiency,environmental friendliness and fuel flexibility.As the critical part of SOFC,the performance of electrolyte directly determines the performance of SOFC.The electrolyte material commonly used in SOFC is partially yttria-stabilized zirconia(YSZ),but due to its high operating temperature(about 1000℃),it brings difficulties in electrode material selection,sealing and so on.Therefore,the development of electrolytes suitable for low and intermediate temperature is essential to promote the commercialization of SOFC.The conductivity of single element-doped ceria electrolyte is higher than that of YSZ at low and intermediate temperatures.However,the disadvantages of CeO_(2)-based electrolytes are that they exhibit electronic conduction due to reduction of Ce^(4+)to Ce^(3+) at lower oxygen partial pressures environments as well as the decrease of total conductivity due to the high grain boundary resistance at low and medium temperatures.Many factors affect the conductivity of CeO_(2)-based electrolytes,such as the preparation method of the powder,the microscopic morphology of the sintered body,and the type and concentration of dopants.Among them,the more important factors are the type of doping elements and its concentration,the preparation method of the powder.Inview of the above problems,researchers generally believe that co-doped or multi-doped(especially doping with rare earth elements)ceria which compared with single element-doping is more beneficial to improve the ionic conductivity of CeO_(2)-based electrolytes and inhibit electronic conductivity.In addition to element doping,ceria-based electrolytes composited with different carbonates have also attracted the interest of researchers.In terms of preparation methods,different powder preparation methods such as microwave sintering,polyols method,and electrostatic spinning can also be used to obtain electrolytes with high ionic conductivity.In addition,thinning the electrolyte to a film and depositing a layer membrane on the CeO_(2)-based electrolyte substrate by pulsed laser deposition(PLD)can reduce electronic conductivity and improve conductivity.In this paper,based on the research status of CeO_(2)-based electrolyte in recent years,the influence of element doping,the preparation method of powder and electrolyte film on the electrical properties of CeO_(2)-based electrolyte is briefly described,and its development is prospected.