Beyond Pretty Pictures to Useful Quantities: The Next Step in 3D Quantification of SOFC Electrodes

Global demands for energy storage, supply and portability has seen continual increase. Meeting these demands in a clean efficient manner will be expedited through an ability to directly image energy devices such as SOFC electrodes, in 3D, at high resolutions. Tomographic techniques allow for the 3D imaging and characterisation of complex electrode microstructures down towards tens of nanometers; which are inadequately described in 2D. The performance of the electrode is dependent on nano/micro-structure as the electrochemical reactions and transport phenomena are strongly affected by the complex porous structure. Furthermore, during processing or operation microstructural evolution may degrade electrochemical performance. However, although many studies have utilised 3D imaging, there is a need to understand the information beyond common metrics .e.g. porosity and tortuosity and pretty pictures. Increasingly large quantities of 3D or time-resolved 3D electrode data are simultaneously acquired and yet poorly understood, simply in favour of more 3D data acquisition. Here we use tomographic techniques (X-ray & FIBSEM) to probe the 3D SOFC electrode structure at nanometer to micrometer length scales. Advanced characterisation of particle specific attributes e.g. necks, interfaces and particle clustering within SOFC electrodes is derived; the electrode is not treated as three monolithic phases. The electrode is quantified as the interaction of particles of three phases. Micro/nano structural changes are followed to facilitate understanding the differences which occur with shape, structures and morphology at high resolution. Results reveal clustering behaviour of particles. The results are also correlated with measured experimental values to provide insight into microstructure-property relationships. We correlate models and this advanced 3D quantitative analysis. In doing so, altogether this work provides important insights for electrode design, enabling 3D optimised structures to be created and understanding sources of performance degradation.