Our team leverages the most recent advancements in cryogenic atom probe tomography and transmission-electron microscopy to gain a deeper understanding of degradation processes. The findings highlight the role of advances in microscopy and microanalysis in providing new insights into the changing microstructures of active materials, which helps in the design of improved materials.
APT is a valuable characterization technique that can map the distribution of elements in nanostructured materials with 3D capability, sub-nanometer resolution, and the ability to detect elements at the ppm level, regardless of mass or composition. Since the first commercial atom probe was developed in 2006, it has been used in various fields, including geoscience, material science, and bioscience. Our group has recently developed cryogenic APT for air- and beam-sensitive battery and energy materials. The samples are prepared in a N2/Ar glovebox and freeze-dried in liquid N2, then transferred to a SEM/FIB using a cryogenic, ultra-high-vacuum suitcase for analysis.
Using cryo-APT, we are able to study the evolution of structure and composition in energy materials. For example, we have used this technique to study a bulk Na sample for use in a future sodium-ion battery electrode. By slicing the sample into a small lamella and sharpening it into a needle-like atom probe specimen, we were able to suppress the uncontrolled ion-beam milling behavior of the low-melting-point alkali metal. Our datasets allowed us to successfully investigate the bulk chemical fluctuations and adsorbed hydrogen concentration of the Na sample.
