Battery Materials and Systems
The morphology and microstructure of electrodes and solid electrolytes and, in particular, the interface within and between materials play a crucial role for battery performance and long term stability. The aim of the research unit 'Advanced Electron Microscopy in Materials Research' is to use and develop advanced electron microscopy techniques ranging from classical TEM and STEM imaging in combination with EELS and EDX spectroscopy to tomography and further to 4D-STEM techniques such as crystal orientation (ACOM) or field mapping (DPC) to provide structural and functional information from the atomic scale to the micron level and relate it to transport and degradation processes in batteries using both ex situ and in situ approaches.
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Non-flammable solid electrolytes are used to reduce the fire risk when the batteries thermal run away and potentially enhance the energy density of batteries. However, they introduce more solid-solid interfaces to the system to increase the charge transfer resistance. Moreover, this drawback was investigated dominantly resulting from the microstructure of the interface or solid electrolytes. To characterize the buried interface and its microstructure within the bulk material using the electron microscopy, we have to use the cryo-FIB to get access to the reliable one minimizing the beam effect or beam damage to the sample. For some cases, the cryo condition and low electron dose are also necessary for reliable TEM characterization in nano scale in case the material is degraded during electron irradiation.
