Article

Surface Science Discoveries: Using TOF-SIMS in Quantum Computing & Battery Innovation

Surface Analysis Spotlight: TOF-SIMS

by Jacob Schmidt Staff Scientist

In this review, we are reflecting on the use of Physical Electronics TOF-SIMS instrumentation in the emerging technologies of quantum computing and energy storage. Research into quantum computing is growing exponentially, and the increasing adoption of energy storage devices in EVs and home energy systems is driving demand for more surface science applications. Here we discuss how TOF-SIMS analysis was used in a quantum computing development and lithium-ion battery recycling.

In the first paper highlighted here, scientists from The City College of New York introduced an innovative solution to address a persistent challenge in the realm of 3D topological insulators - the constraint imposed by the intrinsic conduction of the bulk material on the achievable thickness of the insulator¹. By introducing H⁺ ions into a crystal of Bi₂Te₃, they successfully preserved the distinctive topological properties of the insulator while eliminating the limitations associated with bulk conduction. This novel method for precise tuning of topological insulators holds significant promise for a range of applications, including the field of quantum computing. In this work, the researchers utilized a Physical Electronics nanoTOF to image the Te layer of the crystal (Figure 1b) and extracted the Te-H signal from naturally occurring Te isotopes to provide clear confirmation of the binding of H⁺ ions to Te (Figure 1c and 1d). This development could potentially broaden the range of materials available for use in quantum computing devices.

	Figure 1 – (b) ToF-SIMS images of Te, Bi, and Si substrate. (c) Secondary ion mass spectrum showing 1H, 128Te, 209Bi, and 129[Te-H]. (d) Expanded view of Te isotope mass range showing [Te-H] moieties.

In the second study reviewed here, researchers investigated a novel lithium recycling procedure in which the lithium from a Li-enriched electrode is extracted from the LLZTO electrolyte yielding LiOH and H₂ gas². Notably, this extraction is achieved through a reagent-free and repeatable current-driven method, offering substantial potential for lithium-ion battery recycling. In this work, they used a PHI nanoTOF II to monitor the extraction of lithium ions from the Li-enriched electrode while examining the stability of the transition metal elements. Surface analysis of a LiFePO₄ electrode (Figure 1a) shows near complete extraction of Li^- from the surface. Additionally, through depth profiling (Figure 1b), they were able to visualize a uniform and homogeneous diminishing of the Li^- signal over a depth of 200 nm with no corresponding loss of the transition metal elements. TOF-SIMS analysis was integral in showing the preserved integrity of the LiNi_0.5Co_0.2Mn_0.3O₂ electrode and the efficiency and repeatability of the lithium extraction.

Figure 2 – (a) TOF-SIMS image of the LiFePO4 electrode before (bottom) and after (top) Li extraction. (b) 3D representation of TOF-SIMS depth profile before (bottom) and after (top) Li extraction. 

1. https://www.nature.com/articles/s41467-022-29957-3
2. https://www.science.org/doi/10.1126/sciadv.abq7948