Lithiation Gradients and Tortuosity Factors in Thick NMC111-Argyrodite Solid-State Cathodes

Depth-selective x-ray diffraction using energy-dispersive x-ray detector and straight capillary optics

Depth-selective x-ray diffraction (XRD) technique was developed. In this technique, XRD spectra were measured using an energy dispersive (ED) x-ray detector at fixed angles. A straight capillary optic was used to define the incident x-ray beam, and a second straight capillary defined the beam path from the sample to detector. Thereby, only the XRD spectrum at the small intersection of two capillary optics could be obtained. A depth-selective XRD is possible by changing the sample position in depth. Many XRD peaks appear in a high-energy range more than 10 keV in the ED spectrum. The detection of these peaks will be advantageous for depth analysis because of low absorption in the sample. Depth-selective measurement would be advantageous over general XRD. In this study, depth-selective and ED-XRD spectra are demonstrated for the layered sample, which consisted of film-like Si powder and a muscovite film.

Methods for Tomographic Segmentation in Pseudo-Cylindrical Coordinates for Bobbin-Type Batteries

High-resolution X-ray computed tomography (CT) has become an invaluable tool in battery research for its ability to probe phase distributions in sealed samples. The Cartesian coordinates used in describing the CT image stack are not appropriate for understanding radial dependencies, like that seen in bobbin-type batteries. The most prominent of these bobbin-type batteries is alkaline Zn-MnO2, which dominates the primary battery market. To understand material radial dependencies within these batteries, a method is presented to approximate the Cartesian coordinates of CT data into pseudo-cylindrical coordinates. This is important because radial volume fractions are the output of computational battery models, and this will allow the correlation of a battery model to CT data. A selection of 10 anodes inside Zn-MnO2 AA batteries are used to demonstrate the method. For these, the pseudo-radius is defined as the relative distance in the anode between the central current collecting pin and the separator. Using these anodes, we validate that this method results in averaged one-dimensional material profiles that, when compared to other methods, show a better quantitative match to individual local slices of the anodes in the polar θ-direction. The other methods tested are methods that average to an absolute center point based on either the pin or the separator. The pseudo-cylindrical method also corrects for slight asymmetries observed in bobbin-type batteries because the pin is often slightly off-center and the separator often has a noncircular shape.