【作者】 王楠；

【导师】 朱成军；

【作者基本信息】 内蒙古大学 ， 物理学， 2025， 硕士

【摘要】 固体氧化物燃料电池（Solid Oxide Fuel Cell,SOFC）作为一种高效、清洁的能源转换技术,因其高能量转换效率、全固态组件以及无污染排放等优点而备受关注。然而,传统SOFC需要在（800-1000°C）的较高温度下运行,以实现足够的离子电导率和燃料催化反应需求,这导致了高成本、启动时间长和耐久性差等问题,严重制约了其商业化发展。因此,降低SOFC的工作温度是其商业化发展的必然趋势,而开发在低温下（<600℃）具备高离子电导率的新型电解质材料是加快其低温化进程的有效途径之一。目前,电解质材料的优化研究主要集中在两方面,一是通过引入缺陷和氧空位等方法提升材料本身的离子电导率;二是构建异质结构复合电解质,通过界面处的内建电场驱动离子传输进而获得高效的性能输出。基于此,本文以稀土C型相的Sm₂Ce₂O₇（SCO）为基体材料,通过结构掺杂以及异质结构复合材料的设计,分步开发了具有优异离子电导特性的新型电解质材料,最终获得了低温下性能优异的燃料电池器件,具体研究内容如下所示:首先,采用溶胶凝胶法制备了Y³⁺掺杂的Sm₂Ce_2-xY_xO_7-δ电解质材料,通过优化掺杂比例以获得高性能改性电解质Sm₂Ce_1.8Y_0.2O_7-δ(SCY_0.2),其燃料电池器件在550°C下实现了0.1377S·cm^-1的离子电导率、1.107 V的开路电压（OCV）以及885.9 m W·cm^-2的最大功率密度（MPD）,相比于未掺杂SCO电解质的MPD(739 m W·cm^-2)提升约19.8%。研究发现SCY_0.2改性电解质电化学性能提升的原因在于Y³⁺离子对Ce⁴⁺离子的B位掺杂通过电荷补偿机制在该电解质中提供了更多的氧空位。这些氧空位作为氧离子传输的关键位点,不仅显著提高了材料的离子传输能力,而且通过优化离子迁移路径降低了活化能,从而大幅提升了燃料电池器件的电化学性能。这一研究结果不仅证实了Y³⁺掺杂策略在优化SCO电解质性能方面的有效性,同时为高性能SOFC电解质材料的开发设计提供了一条新的有力途径。接着在上一章所得的高性能SCY_0.2电解质的基础上,引入宽带隙半导体材料Sn O₂构建了一种新型SCY_0.2-Sn O₂异质结构复合电解质来进一步提升电池的电化学性能并降低其工作温度。实验结果表明:最佳复合比的7SCY_0.2-3Sn O₂电解质在550℃下获得了0.188 S·cm^-1的优异离子电导率以及1120 m W·cm^-2的MPD,相比于单相SCY_0.2电解质的MPD提升约21%,并且在385℃的低温下仍能实现95 m W·cm^-2的功率输出,展现了良好的低温特性。研究发现该复合电解质性能提升主要归因于两方面:一是两相材料因其能带结构差异会在异质界面处产生内建电场,该电场能够加速电解质内部的离子转移并且抑制电子传导,从而显著提升其离子电导率。二是SCY_0.2-Sn O₂复合体系可以降低渗透在电解质内部的Li₂CO₃/Li OH络合物熔点,该熔融态络合物能够维持复合电解质异质结构在低温下的完整性,从而提高了其在低温下的离子迁移速率。基于场效应与熔点调控行为的协同作用,最终SCY_0.2-Sn O₂复合电解质实现了SOFC器件整体电化学性能的显著提升。该研究为低温高性能SOFC复合电解质的开发提供了新的见解与设计思路。更多还原

【Abstract】 Solid Oxide Fuel Cell（SOFC）,as an efficient and clean energy conversion technology,has attracted much attention due to its high energy conversion efficiency,all-solid-state components and pollution-free emissions.However,conventional SOFC need to operate at higher temperatures（800-1000°C）to achieve sufficient ionic conductivity and fuel-catalyzed reaction requirements,resulting in high costs,long start-up times and poor durability,which will severely limit their commercial development Therefore,reducing the operating temperature of SOFC is the inevitable trend of its commercial development,and the development of new electrolyte materials with high ionic conductivity at low temperatures（<600℃）is one of the effective ways to accelerate its cryogenic process.At present,the optimization research of electrolyte materials mainly focuses on two aspects.The first method is to improve the ionic conductivity of the material by introducing defects and oxygen vacancies.The second method is to construct heterostructure composite electrolytes,and obtain efficient performance output by driving ion transport through the internal electric field at the interface.Based on this,this study takes the rare earth C-phase Sm₂Ce₂O₇（SCO）as the base material,develops a new electrolyte material with excellent ionic conductivities step by step through structural doping and the design of heterostructure composite materials,and finally obtains a fuel cell device with excellent performance at low temperature.Specific research contents are shown as follows:Firstly,Sm₂Ce_2-xY_xO_7-δelectrolyte doped with Y³⁺was prepared by sol-gel method,and the high performance modified electrolyte Sm₂Ce_1.8Y_0.2O_7-δ(SCY_0.2)was obtained by optimizing the doping ratio.The fuel cell device achieved an ionic conductivity of 0.1377 S·cm^-1 at 550°C,open circuit voltage（OCV）of 1.107 V,and maximum power density（MPD）of 885.9 m W·cm^-2,19.8%improvement over MPD(739 m W·cm^-2)with undoped SCO electrolytes.It was found that the reason for the improvement of electrochemical performance of SCY_0.2 modified electrolyte was that Y³⁺ions doped Ce⁴⁺ions at B site provided more oxygen vacancies in the electrolyte through charge compensation mechanism.As the active site of oxygen ion transport,these oxygen vacancies not only significantly improve the ion transport capacity of the material,but also reduce the activation energy by optimizing the ion migration path,thus greatly improving the electrochemical performance of the fuel cell device.The results of this study not only confirm the effectiveness of Y³⁺doping strategy in optimizing the performance of SCO electrolytes,but also provide a new and powerful way for the development and design of high-performance SOFC electrolyte materials.Then,on the basis of the high performance SCY_0.2 electrolyte obtained in the previous chapter,a new SCY_0.2-Sn O₂ heterostructure composite electrolyte was constructed by introducing the wide-band gap semiconductor material Sn O₂ to further improve the electrochemical performance of the battery and reduce the operating temperature.The experimental results show that:The 7SCY_0.2-3Sn O₂ electrolyte with the best recombination ratio achieved an excellent ionic conductivity of 0.188S·cm^-1 and MPD of 1120 m W·cm^-2 at 550℃,which is about 21%higher than that of single-phase SCY_0.2 electrolyte.And the power output of 95 m W·cm^-2 can still be achieved at a low temperature of 385℃,showing good low temperature characteristics.It is found that the performance improvement of the composite electrolyte can be mainly attributed to two aspects:First,the two-phase material will generate a local electric field at the heterostructure interface due to the difference of its energy band structure,which can accelerate the ion transfer inside the electrolyte and inhibit the electron conduction,thus significantly improving its ion conductivity;Second,the SCY_0.2-Sn O₂composite system can reduce the melting point of the Li₂CO₃/Li OH complex permeated in the electrolyte,and the molten complex can maintain the integrity of the heterostructure of the composite electrolyte at low temperatures,thereby improving the ion migration rate at low temperatures.Based on the synergistic effect of field effect and melting point regulation behavior,SCY_0.2-Sn O₂ composite electrolyte can significantly improve the overall electrochemical performance of SOFC devices.This study provides new insights and design ideas for the development of low temperature and high performance SOFC composite electrolytes.更多还原