Tailoring of microstructural evolution in impregnated SOFC electrodes

固体氧化物燃料电池是高度复杂的器件，具有许多界面，通常在高温下形成。这在化学和物理兼容性方面对这些设备施加了许多限制，限制了性能和耐用性。这些问题强烈地限制了材料的选择，并对SOFC制造施加了重大的成本惩罚。利用溶液方法引入部分SOFCs活性成分是一种非常有吸引力的方法，近年来引起了人们的极大兴趣。这可能涉及纳米颗粒的渗透或前驱体溶液的浸渍，以形成原位相。可以使用更低的反应温度，避免兼容性问题，并提供更广泛的材料选择。典型地，这种过程包括通过高温处理形成支架结构，然后通过低温方法浸渍电极。我们已经成功地将这种方法应用于SOFC架构的三种不同的新变体。这些是电解质支撑的氧化物阳极，氧化物阳极支撑和金属阳极支撑电池。可获得优异的性能，并表现出良好的氧化还原性能；然而，需要取得进展，以确保高耐用性。浸渍剂倾向于形成分散良好的纳米颗粒，但在燃料电池运行条件下，随着时间的推移，这些纳米颗粒可能会聚集在一起，从而降低整体性能。通过我们应用浸渍概念的国家和欧洲项目，我们学到了很多关于浸渍和如何开发适当分散的电极结构的知识。电极结构随着使用而演变，并且通过改进处理存在优化结构的明确机会。最重要的是认识到在浸渍的材料、基材和所用溶剂之间有很强的相互作用。即使是电极成分的细微变化，也需要在浸渍化学方面进行重大改变，以保持最大的性能水平。在这个项目中，我们寻求进一步开发这种浸渍化学的控制，从而开发通过跨几个平台的溶液路线开发受控微观结构的通用方法。这些新的化学物质将应用于电解质和阳极支持的SOFC几何形状和性能，以优化性能、耐久性和氧化还原耐受性。总体目标是开发并证明这种新方法可以成功地应用于燃料电池的制造，从而结合高性能、耐用性和抗污染物性。我们将把这种方法典型地应用于带有金属催化剂的氧化锆、钛酸锶和金属支架的浸渍氧化物电极，并在这一系列平台上发展我们对基础化学的理解。通过这样做，我们将开发出在广泛的组合空间范围内定制浸渍的方法。利用电化学、光谱和微观结构技术对浸渍系统的性能、耐久性和抗污染物性进行研究，为浸渍系统的选择提供信息。最终的成果将是为不同的SOFC应用模式和几何形状提供新颖的定制化学品，在SOFC开发人员准备好的规模上展示具有强大、高性能特性的新型电池技术，并为SOFC制造开发新的路线和仪器。

Solid oxide fuel cells are highly intricate devices with many interfaces which are typically formed at high temperatures. This places many constraints in terms of chemical and physical compatibility upon such devices limiting both performance and durability. Such problems strongly restrict materials choice and impose significant cost penalties on SOFC manufacture. The utilisation of solution methods to introduce part of the SOFCs active constituents is a highly attractive approach that has gained much interest in recent years. This can involve infiltration of nanoparticles or impregnation of precursor solutions to form phases in situ. Much lower reaction temperatures can be utilised avoiding problems with compatibility and affording wider materials choice. Typically such process involves formation of a scaffold structure by high temperature processing and then impregnation of an electrode by lower temperature methods. We have successfully applied this approach to three different novel variants of SOFC architectures. These are electrolyte supported oxide anodes, oxide anode supported and metal anode supported cells. Excellent performances can be obtained and good redox properties demonstrated; however, progress needs to be made to ensure high durability. The impregnates tend to form well dispersed nanoparticles, but these might be expected to agglomerate over time, in fuel cell operating conditions, to reduce overall performance. Through the national and European projects where we applied the impregnation concept, we have learned much about impregnation and how to develop appropriately dispersed electrode structures. The electrode structure is seen to evolve with use and clear opportunities exist to optimise structures through improved processing. Most important has been the realisation that there are strong interplays between the materials impregnated, the substrate and the solvent utilised. Even subtle changes in electrode composition, demand significant changes in impregnation chemistry to maintain the maximum levels of performance. In this project we seek to further develop control of this impregnation chemistry and hence to develop generic methods for developing controlled microstructures via solution routes across several platforms. These new chemistries will be applied to electrolyte- and anode-supported SOFC geometries and properties optimised for performance, durability and redox tolerance. The overall objective is to develop and demonstrate this new approach as one that can be successfully applied to manufacture of fuel cells that combine high performance with durability and resistance to contaminants. We will apply this approach typically for an impregnated oxide electrode with metallic catalyst to zirconia, strontium titanate and metal supports and develop our understanding of the fundamental chemistry across this range of platforms. By so doing we will develop methodologies to tailor impregnations over a broad range of composition space. Studies of performance, durability and resistance to contaminants utilising electrochemical, spectroscopic and microstructural techniques will be used to inform choice of impregnate systems. Final outcomes will be delivery of novel tailored chemistries for different SOFC application modes and geometries, demonstration of novel cell technologies with robust, high performance characteristics at SOFC developer ready scales and development of new routes and instrumentation for SOFC manufacture.