Structure, Reactivity and Transport at Surfaces and Interfaces of Doped Ceria Electrolytes and Cermets: An In Situ Atomic Resolution Investigation

非技术描述：随着社会走向可持续能源，开发高效的发电方法是一个关键目标。固体氧化物燃料电池是将储存在化学燃料中的能量直接转化为电能的一种很有前途的方法。这些陶瓷电池在高温下运行，可以利用天然气、生物燃料和汽油等多种燃料。与其他燃料电池技术相比，这种燃料灵活性是固体氧化物燃料电池的一个显著优势。不幸的是，这些设备价格昂贵，而且由于其较高的工作温度而不能表现出长期的稳定性。这些问题中的许多可以通过开发新材料来解决，这些材料将允许固体氧化物燃料电池在较低温度下可靠地运行。新材料的开发需要燃料电池中材料在恶劣条件下的行为信息。该项目利用了一种强大的技术--电子显微镜，它能够在类似于真实燃料电池的条件下直接观察材料中发生的原子水平变化。这些信息提供了对结构重排如何导致材料正功能或负功能的基本理解。反过来，这些信息也被用来帮助设计新材料，以提高燃料电池的性能。研究生、本科生和高中生都参与了这项研究。这些研究活动帮助他们了解如何利用材料研究来解决重要的社会问题，如可持续能源技术的发展。技术细节：离子传输特性和化学反应是影响固体氧化物燃料电池技术的关键因素。与高温操作相关的成本和长期稳定性问题是尚未解决的材料设计挑战。这些问题推动了所谓的中温固体氧化物燃料电池的发展，这种燃料电池使用了能够在较低温度(500-700摄氏度)下提供高离子导电性和催化活性的新材料。掺杂稀土氧化物是一种非化学计量比的稀土氧化物，具有较高的离子电导率和良好的催化性能，在中温领域具有潜在的应用前景。然而，与电解液中跨晶界的相互作用以及阳极中陶瓷-金属和固-气界面的相互作用有关的重要科学问题仍有待解决。这个项目通过使用原位像差校正的电子显微镜和单色电子能量损失谱来解决这些问题，以发展对这些界面过程的基本原子水平的理解。影响电解液和阳极金属陶瓷中离子导电性和反应性的纳米结构和化学成分正在被确定。一种新的实验方法正在开发中，以允许在电化学条件下对电陶瓷进行原位原子分辨观察。这项研究具有潜在的变革性，因为它提供了关于结构和化学与电化学和电陶瓷功能相关的动态过程的新信息。这项研究项目旨在培养研究生和本科生了解和促进与能源相关的氧化物材料的发展。

NON-TECHNICAL DESCRIPTION: Developing efficient methods for generating electricity is a critical goal as society moves towards sustainable energy. Solid oxide fuel cells are a promising approach for efficiently converting the energy stored in chemical fuels directly to electricity. These ceramic cells run at high temperatures and can utilize a wide range of fuels such as natural gas, biofuels and gasoline. This fuel flexibility is a significant advantage of solid oxide fuel cells compared to other fuel cell technologies. Unfortunately, these devices are expensive and do not show long term stability because of their high operating temperatures. Many of these issues may be solved by developing new materials that would allow reliable operation of the solid oxide fuel cell at lower temperatures. Development of novel materials requires information on the behavior of materials under the harsh conditions present in a fuel cell. This project utilizes a powerful technique, electron microscopy which enables direct observation of atomic level changes taking place in materials under conditions similar to those present in a real fuel cell. This information provides a fundamental understanding of how the structural re-arrangements result in positive or negative materials functionalities. In turn, this information is being used to help in the design of new materials for improved fuel cell performance. Graduate, undergraduate and high school students are involved in this research. These research activities help them to understand how materials research can be employed to address important societal problems like the development of sustainable energy technologies.TECHNICAL DETAILS: Ionic transport properties and chemical reactivity are key factors impacting solid oxide fuel cell technologies. Cost and long-term stability problems associated with high temperature operation are unresolved materials design challenges. These issues have motivated the development of so-called intermediate temperature solid oxide fuel cells which employ novel materials that can deliver high ionic conductivity and catalytic activity at lower temperatures (500 - 700 C). Doped cerias are nonstoichiometric rare earth oxides which show high ionic conductivity and desirable catalytic properties making them potential candidates for use in intermediate temperature applications. However, there are important unresolved scientific questions related to interactions across grain boundaries in electrolytes as well as ceramic-metal and solid-gas interfaces in anodes. This project addresses these questions by using in situ aberration corrected electron microscopy along with monochromated electron energy-loss spectroscopy to develop a fundamental atomic level understanding of these interfacial processes. The nanoscale structures and chemistries affecting ionic conductivity and the reactivity in electrolytes and anode cermets are being determined. A new experimental approach is being developed to allow in situ atomic resolution observations of electroceramics under electrochemical conditions. This research is potentially transformative because it is providing new information on the dynamic processes relating structure and chemistry with electrochemical and electroceramic functionalities. This research project is training graduate and undergraduate students to learn about and contribute to the developments in energy-related oxide materials.