【作者】 王震；

【导师】 董文静；

【作者基本信息】 湖北大学 ， 电子科学与技术， 2023， 硕士

【摘要】 降低操作温度是固体氧化物燃料电池（SOFC）商业化的必要途径。然而,在低温下传统SOFC电极材料的催化活性和电解质的离子电导率显著降低,严重限制了其应用。因此,发展新型电极和电解质材料迫在眉睫。近年来,一种新型的半导体离子隔膜燃料电池因其在低温下优异的性能逐渐引起了人们的广泛关注。其使用的三重导电材料Ni_0.8Co_0.15Al_0.05LiO_2-δ（NCAL）在电池中起着非常重要的作用,研究表明,NCAL具有良好的氢氧化（HOR）和氧还原（ORR）催化性能,其在氢气作用下极易被还原,这对于其催化活性和电解质的离子导电性都会产生一定的影响。为了更进一步理解NCAL的导电性和还原稳定性对电池性能的影响规律,本研究围绕NCAL的成分特点,设计了四种不同的含碱金属元素的金属氧化物材料。它们的电子导电性和在氢气中的稳定性不同,包括:易还原、电子电导率大的材料（LiNiO₂和LiCoO₂）和不易被还原、电子电导率小的材料（LiAlO₂和NaFeO₂）。论文研究了这四种材料的单相和复合相分别作为电极和电解质的特性,以理解NCAL的性质与其在半导体离子隔膜燃料电池中扮演的角色之间的关联。本研究将为半导体离子隔膜燃料电池工作机制的理解和电池性能的提升提供一定的参考。具体研究内容如下:1)用固相法分别合成了LiNiO₂（LNO）、LiCoO₂（LCO）、LiAlO₂（LAO）、NaFeO₂（NFO）这四种材料,并对它们进行XRD和SEM表征。此外,研究了这四种材料在氢气中的还原稳定性。通过将材料使用氢气处理,并进行XRD表征,发现经过氢气处理后,LNO和LCO被还原了,而LAO和NFO则没有发生改变。2)为了理解基于锂过渡金属氧化物（LMO）材料的燃料电池中影响电池性能的主要因素,研究了几种不同导电性、还原稳定性、催化性的材料分别作为电池的电极和电解质的可能性。使用单相LMO作为电极与Sm掺杂氧化铈（SDC）电解质构造燃料电池,以及以单相LMO作为电解质、NCAL作为电极构造燃料电池,研究了LMO的导电性对电池性能的影响。进一步,研究了两种LMO的复合材料在SOFC中作为电极和电解质的可行性,以及作为电极和电解质时对LMO材料的性能的要求。3)考虑NCAL对电池性能的影响与其产生的LiOH/Li₂CO₃有关,而LiOH/Li₂CO₃等的产生及其对电池中离子传导的影响与水蒸气和二氧化碳有关,本章研究了电池的阴极和阳极中二氧化碳与水蒸汽的加入对电池性能影响。研究了以NCAL为电极的电池中3%-10%的水蒸气以及不同浓度CO₂的引入对电池的输出功率以及微观形貌的影响。同时,对比分析了使用不同电极的电池中二氧化碳和水的引入带来的影响。结果表明,二氧化碳和水的引入会导致电池性能的极大下降。更多还原

【Abstract】 Lowering the operation temperature of solid oxide fuel cell（SOFC）is important for its commercialization.With the reduction of operation temperature,the performance of traditional SOFC materials is severely degraded,which leading to the limitation of them in low temperature.Accordingly,developing new type of electrode and electrolyte materials is urgently needed.In recent years,a new type of fuel cell,semiconductor-ionic conductor membrane fuel cell（SICFC）,has drawn a great attention due to its extraordinary performance at low temperature.It has been reported that a triple conducting material,Ni_0.8Co_0.15Al_0.05LiO_2-δ（NCAL）,plays an important role in SICFC,and it exhibits excellent hydrogen reduction reaction（HOR）and oxygen oxidation reaction（ORR）catalytic activity.Besides,NCAL can be easily reduced in hydrogen atmosphere when used as anode,which results in the affection of the catalytic activity of the electrode and ionic conductivity of the electrolyte.In order to further understand the influence of conduction and reductive stability of NCAL on cell performance,this study tries to design 4 different lithium transition metal oxides which varied in electronic conductivity,and reductive stability.LiNiO₂ and LiCoO₂ that show high electronic conductivity and are easy to be reduced in hydrogen atmosphere,as well as LiAlO₂and NaFeO₂ that contain low electronic conductivity and are stable in hydrogen atmosphere have been studied.The application in electrode and electrolytes of the four kinds of materials has been investigated in order to understand the relationship between the property of the material and their applications in SOFC.This study will help understanding the working mechanism of SICFC that using these lithium containing materials,and also provide references for the optimization of the cell performance.The following issues are included:1)LiNiO₂（LNO）,LiCoO₂（LCO）,LiAlO₂（LAO）and NaFeO₂（NFO）are synthesized using a solid-state reaction method.The morphology and phase structure of the materials were studied by SEM and XRD,respectively.Besides,their stability in hydrogen atmosphere is studied by treating the materials in hydrogen at the working temperature.XRD results suggest that LNO and LCO are reduced by hydrogen while LAO and NFO are stable.2)In order to understand the key issues of these lithium transition metal oxides（LMOs）that influence the performance of fuel cell,the possibility of using four kinds of materials with different conductivity,reduction stability,and catalytic properties as electrodes and electrolytes in SOFC is investigated.Two types of cells are constructed,the first one is made using single-phase LMO as the electrode and Sm-doped cerium oxide（SDC）electrolyte,and second one is using single-phase LMO as the electrolyte and NCAL as the electrode.The output performance of the cells at 550℃ and the XRD and SEM of the materials after operation were studied.The effect of the conductivity of LMO on cell performance is studied.Furthermore,the feasibility of using the two LMO composites as electrodes and electrolytes in SOFC,and the requirements of LMO materials as electrodes and electrolytes are studied.3)Considering that the effect of NCAL on cell performance is related to the generation of LiOH/Li₂CO₃ from NCAL during cell operation,and the production of LiOH/Li₂CO₃ as well as its influence on the ion transportation property is related to water vapor and carbon dioxide,carbon dioxide and water vapor are respectively added in the cathode and anode of the cells in order to study its influence on the cell performance.The effects of the introduction of 3%-10%water vapor and different concentrations of CO₂ on the output power and microscopic morphology of the NCAL electrode-based cell are studied.At the same time,the influence of the introduction of carbon dioxide and water in SOFC using different electrodes are compared and analyzed.The results show that the introduction of carbon dioxide and water leads to a significant decrease in fuel cell performance.更多还原