High-Resolution 3D Chemical Imaging of Light Elements by Time-of-Flight Mass Spectrometry

Valentine Riedo-Grimaudo¹_, Lex Pillatsch¹, James Whitby¹, Renato Pero², Nicholas Randall², Masoud  Baghernejad^3 
1TOFWERK, Thun, Switzerland, ² Alemnis AG, Thun, Switzerland, ³ Helmholtz-Institute Münster, Forschungszentrum Jülich GmbH, Münster, Germany. 
EMC 2024 Poster

High-Resolution 3D Chemical Imaging of Light Elements: Probing Nanometer-Scale Structures via Time-of-Flight Mass Spectrometry for Advanced Material Analysis in Batteries and Metallurgy

This poster presented at the EMC 2024 conference demonstrates the use of time-of-flight mass spectrometry (TOFMS) for high-resolution 3D Chemical Imaging of Light Elements.

It is a common practice to correlate multiple imaging techniques to achieve a comprehensive understanding of the interplay between material structure and function. Beyond the geometric structure, the chemical composition, particularly at the nanometer scale, plays an essential role. However, there is a shortage of instruments capable of imaging light-mass elements with sufficiently high spatial resolution and sensitivity. This gap is addressed by TOFWERK’s fibTOF platform, offering high spatial resolution and 3D chemical imaging of all the elements of the periodic table, including light-mass elements. This capability is demonstrated through the application examples below, which are taken from the battery and metallurgy sectors. 

The fibTOF is a Secondary Ion Mass Spectrometry (SIMS) detector designed to be attached to a Focused Ion Beam (FIB) Scanning Electron Microscope (SEM). The fibTOF extends microscopic analysis to probe the chemical composition of solids at the nanometer scale with sensitivities down to the ppm range.  The properties of a FIB as a primary ion source to erode and ionize material is used. For each pixel probed by the FIB, the released secondary ions are extracted and characterized. The combination of the mass spectra/pixel, results in an intensity map of elements for a mass range of 0-500 Th. As the FIB repeatedly scans the region of interest (ROI), a 3D data set is generated.  

The value of the fibTOF is demonstrated by the investigation of a Solid-Electrolyte Interface (SEI) composition at the anode after galvanostatic cycling. We explore how various molecular additives affect its stability.  

Lithium ions have been observed at various penetration depths, indicating differences in SEI formation efficacy based on the additives used. The lower SEI formation efficiency explains the diminished battery performance due to ongoing electrolyte degradation. In addition, measurements of Mn and Ni on the anode corroborate irreversible phase changes and metal dissolution of the cathode. 

The use of the fibTOF has been shown as well in correlation with hardness tests done by nanoindentation of an M3 high-speed steel alloy. Certain regions of the sample, chemically characterized as hard phases, exhibited soft mechanical properties. These regions also showed the presence of hydrogen, hinting at a potential link to hydrogen embrittlement. Notably, both case studies were carried out using elevated sputtering and detection rate of the fibTOF. 

The studies presented demonstrates the efficacy of the fibTOF in light-mass element imaging, showcasing its versatility and reliability in analyzing diverse materials and complex microstructures. Furthermore, the demonstrated capability of the fibTOF to manage enhanced signals bolsters its potential for a broad spectrum of applications. 

References

[1] L. Pillatsch et al., Progress in Crystal Growth and Characterization of Materials, 65, (2019), p. 1. 

[2] J. A. Whitby et al., Advances in Materials Science and Engineering, 2012, (2012), p. 180437.

[3] U. S. Meda et al., Journal of Energy Storage, 47, (2022), p. 103564.  

[4] N. Randall et al., Journal of Materials Research, 24, (2009), p. 679.