Porous electrodes are essential for different kinds of energy storage and conversion devices such as lithium-ion batteries (LiB) and solid oxide fuel cells (SOFC). The microscopic structure of the electrodes determines their performance. Therefore, one needs a tool to investigate the microstructure in order to optimize the electrode structures.
For the reconstruction of solid oxide fuel cell as well as lithium-ion battery microstructures, focused ion beam (FIB) tomography has proven to be a powerful tool. During the reconstruction, thin layers (10 to 100 nm) are removed from the sample and the cross-sections are subsequently imaged by a scanning electron microscope (SEM). The stack of images obtained from this process is then used to investigate the structure, either by calculating characteristic parameters or by generating a mesh for computational studies.
In my PhD thesis I am investigating microstructures of all components of lithium-ion cells (anode, separator and cathode). The variety of cathode materials and their different properties (diffusion coefficients of lithium, electronic conductivity …) leads to a special importance to understand the influence of the microstructure on electrode performance. In addition to characterizing the microstructures, modeling of the fundamental processes provides a tool to understand the coupling between electrochemistry and the electrode’s microstructure (see electrochemical modeling).