Engineering topics

Seidler, Gerald T.

Publications and source records attributed to Seidler, Gerald T..

4 records

DOE OSTI2025

Anode Potential Evolution During Zinc Metal Plating and Stripping in Dual-Solvent Battery Electrolytes

In the field of battery electrolyte research, the importance of the working cation solvation environment has become increasingly more apparent. To optimize bulk properties and, especially, interfacial reactions, multisolvent electrolytes (electrolytes containing two different solvents) have become more prevalent in battery research and development. In this work, we elucidate the relationship between cation solvation and interfacial electrochemistry, demonstrating that preferential solvation of Zn 2+ by a strong coordinating solvent such as 2-methoxyethylamine or ethylenediamine as opposed to a weaker solvent such as 3-methylsulfolane or acetonitrile leads to dynamic evolution in the interfacial energetics during Zn plating and stripping due to local changes in solvent composition and coordination. In some instances, interfacial solvation evolution can shift the reversible potential of Zn plating by as much as 1 V under relatively mild rate conditions. Through these investigations, we establish the generality of this phenomenon, highlight its importance as a consideration in dual-solvent battery electrolytes, and provide direction for tailoring electrochemistry through solvent design.

Hahn, Nathan T.↗

DOE OSTI2024

Asymmetric Rowland circle geometries for spherically bent crystal analyzers in laboratory and synchrotron applications

Spherically bent crystal analyzers (SBCAs) are the dominant high-resolution hard X-ray optic in the ongoing rebirth of laboratory-based X-ray absorption fine structure (XAFS) and X-ray emission spectroscopy (XES) as well as in synchrotron methods such as high energy resolution fluorescence detection (HERFD) and non-resonant X-ray Raman scattering (XRS). In the overwhelming majority of cases, SBCAs are implemented in a ‘symmetric’ configuration on the Rowland circle, wherein the diffracting crystal plane is nominally coincident with the analyzer surface. We report here comprehensive investigations of ‘asymmetric’ operation of SBCA on the Rowland circle, wherein the diffracting crystal plane is not coincident with the optical surface of the analyzer. First, we have developed a laboratory spectrometer for XAFS and XES that is specialized for asymmetric SBCA operation. Here we find several benefits, including the capacity to use a single SBCA over a very wide energy range via ‘hkl hopping’ and the frequent ability to eliminate Johann error, the most prevalent energy-broadening mechanism when using SBCA symmetrically on the Rowland circle. Second, we expand these ideas to synchrotron facilities with a demonstration study of HERFD and XRS where asymmetric operation also provided advantage. Our results suggest that large-array systems for HERFD augmented with an additional mechanical degree of freedom could streamline user operation and also indicate benefits to XRS in the asymmetric configuration, where larger solid angle, larger sample-to-detector distance, and decreased Johann error can be achieved simultaneously.

47 OTHER INSTRUMENTATION↗

DOE OSTI2024

Core-to-core X-ray emission spectra from Wannier based multiplet ligand field theory

Recent advances using Density Functional Theory (DFT) to augment Multiplet Ligand Field Theory (MLFT) have led to ab-initio calculations of many formerly empirical parameters. This development makes MLFT more predictive instead of interpretive, thus improving its value for studies of highly correlated 3 d , 4 d , and ƒ-electron systems. Synchrotron time is always at a premium, and tools that provide predictive capabilities have clear value when it comes to planning studies. Here, in this work, we develop a DFT + MLFT based approach for core-to-core Kα x-ray emission spectra (XES) and evaluate its performance for a range of transition metal systems. We find good agreement between theory and experiment, as well as the ability to capture key spectral trends related to spin and oxidation state. We also discuss limitations of the model in the context of the remaining free parameters and suggest directions forward.

Ab initio theoretical treatment↗

DOE OSTI2024

Accelerating nano-XANES imaging via feature selection

We utilize feature selection to reduce experimental time by ∼80% of a nanoscale X-ray Absorption Fine Structure (XANES) spectroscopy imaging study of a sample with Fe-bearing mineral phases.

36 MATERIALS SCIENCE↗