摘要
固体氧化物燃料电池(SOFC)是一种直接将化学能转化为电能的新型的发电装置，具有清洁的特点、高效的优势和广阔的应用前景。SOFC的能量转化效率可高达60~70%，成为了近些年能源研究的热点。目前虽然对平板式SOFC的研究已获得很大进展，但长时间工作的输出衰减仍然是制约该技术商业化推广的重要原因之一。
SOFC的电池衰减主要由电极和电解质材料在高温、高电流密度和复杂气氛等工作环境下发生的材料物相和微观组织形貌变化带来。目前，相关研究主要集中在电极，特别是阴极的衰减领域，电解质的衰减存在案例报道但研究较少。本文主要研究电解质在燃料电池工作时的电场作用下，金属电极与陶瓷电解质的相容性和扩散行为，以及表征由此带来的电化学与机械性能的变化。
集体利益
本研究采用氧化钇稳定的氧化锆（YSZ）作为电解质材料，以粉末干压成型并高温烧结的工艺制作致密的电解质薄片；以钯（Pd）作为电极，通过丝网印刷工艺印制到电解质薄片表面，烧结后制备得到电极‒电解质样品。将该样品置于850 °C工作温度和空气环境中，以1 A/cm2的电流密度进行极化。选取极化时间为1 h、50 h、100 h、200 h、350 h的样品进行电化学表征，并采样。使用扫描电子显微镜（SEM）测试手段对经过极化测试的电极进行微观形貌的分析，并通过SEM附带的X射线能谱仪（EDX）的线性扫描能谱、X射线光电子能谱分析（XPS）的离子刻蚀深度剖析和聚焦离子束-透射电子显微镜（FIB-TEM）对样品电极与电解质界面处进行分析。
测试结果表明，在电流密度为1 A/cm2的极化电流作用下，极化时间为350 h时，电场作用没有引起Pd与电解质之间发生明显的扩散现象，贵金属电极具有很高的稳定性。然而与电极接触的电解质在经历长时间极化后外观颜色变黑，微观形貌粗糙多孔，并在其表面会附着尺寸远小于典型烧结尺寸的Pd颗粒，且该现象随极化时间延长而愈加显著。同时，电解质断裂强度随极化时间延长而降低。
研究还表征了电流密度为0.75 A/cm2、工作温度750 °C、工作时间为4000 h的全电池中阴极Pd元素和阳极Ni元素与YSZ电解质之间界面形貌，使用SEM及其附带的防台风措施>亚伯拉罕诸教
EDX、FIB-TEM和飞行时间二次离子质谱仪（ToF-SIMS）对全电池截面进行分析，分析表明没有电极元素向电解质中扩散的现象，此外，发现在阴极中，Pd与YSZ的状态有两种，一是Pd纳米颗粒团聚成小颗粒分散在YSZ架构的空隙中；二是Pd被YSZ 包覆，包覆的Pd颗粒呈现出从球心到外具有浓度梯度的颗粒物。
进一步研究了极化电流密度和极化时间对YSZ电解质的机械性能的影响。使用流延成型工艺、丝网印刷、脱脂以及共烧结等工艺制备了直径为22 mm，厚度为0.6 mm 的YSZ圆片作为电解质，以Pd为阴极制作半电池，经过不同的极化电流密度和极化时间后进行硬度、断裂强度测试，并通过SEM和XPS对断裂模式进行微观观察，得出数据，得出极化时间与断裂强度和硬度的相应关系并解释这种现象。
喜剧之王结局关键词：固体氧化物燃料电池Pd电极YSZ 扩散机械性能
ABSTRACT
Solid oxide fuel cell (SOFC) is a new type of power generation system that directly converts chemical energy into electrical energy. It has clean, high-efficiency advantages and broad application prospects. The energy conversion efficiency of SOFC is not limited by the Carnot cycle and can reach 60 to 70 %, becoming a hot spot for energy rearch. In recent years, although rearch on the flat-panel SOFC has made great progress, the output attenuation of long-term work is still one of the important reasons restricting the commercialization of this technology. The battery attenuation of the SOFC is mainly caud by changes in pha and microstructure of materials and materials occurring in electrode and electrolyte materials under high temperature, high current density and complex atmosphere. At prent, related rearch has focud on the attenuation of electrodes, especially cathodes. However, the problems of electrolyte attenuation have less rearch. This paper mainly studies the compatibility and diffusion behavior of metal electrode and ceramic electrolyte under the action of electric field when the fuel cell is working, and characterizing the electrochemical and mechanical properties.
In this study, yttria-stabilized zirconia (YSZ) was ud as the electrolyte material that was prepared by powder dry compression molding and high temperature sintering to make a den electrolyte she
et, and Pd was ud as the electrode to print the surface of electrolyte through screen printing process. After sintering, electrode‒ electrolyte sample were prepared. The sample was polarized at a current density of 1 A/cm2at a working temperature of 850 °C and in an air environment. Electrochemical characterization was performed for samples with polarization times of 1 h, 50 h, 100 h, 200 h, and 350 h. Using a scanning electron microscope (SEM) test method to analyze the micromorphology of the poled electrode, and through the SEM attached X-ray energy spectrometer (EDX) linear scanning energy spectrum, X-ray photoelectron spectroscopy (XPS) ion etching depth
profile and focud ion beam - transmission electron microscopy (FIB-TEM) analyzed the sample electrode and electrolyte interface.
The test results show that The effect of the electric field did not cau significant diffusion between the Pd and the electrolyte, and the noble metal electrode had high stability at a current density of 1 A/cm2 with a polarization time of 350 h. However, after long-time polarization, the appearance of the electrolyte contacted with the electrode is dark and the microstructure is rough and porous that Pd particles with dimensions much smaller than typical sintered sizes are attached to the surfaces. This phenomenon becomes more pronounced as the polarization time increas. At the same time, electrolyte fracture strength decreas with prolonged polarization time.
The study also characterized the interface morphology between the cathode Pd element、the anode Ni element and the YSZ electrolyte of full cell which is at the condition of current density of 0.75 A/cm2, operating temperature of 750 °C and operating time of 4000 hours. Analysis shows that there is no diffusion of electrode elements into the electrolyte by using scanning electron microscopy (SEM) and its accompanying EDX、FIB-TEM spectra and time-of-flight condary ion mass spectrometry (ToF-SIMS). In addition, it is found that there are two kinds of Pd and YSZ states in the cathode. One is that Pd is agglomerated into small particles disperd in the voids of the YSZ framework. The other is that Pd is coated with YSZ and the coated Pd particles exhibit a concentration gradient from the center of the sphere to the outside.草率
审配>陕西师范网络远程教育学院Furthermore, the influence of polarization current density and polarization time on the mechanical properties of YSZ electrolyte was studied. Using the casting process, screen printing, degreasing and co-sintering process prepared YSZ wafer with a diameter of 22 mm and a thickness of 0.6 mm as the electrolyte. Using Pd as cathode made half cell. After a different polarization current density and polarization time, testing the hardness and fracture strength of half-cell and using SEM and XPS obrve the fracture mode microscopically. Finding the corresponding relationship between the
过年乐曲
polarization time, the fracture strength and hardness and explain this phenomenon.
Key words: Solid Oxide Fuel Cell(SOFC) Pd electrode YSZ Diffusion Mechanical properties
