Article

Insights Into Battery Chemistry Using TOF-SIMS, XPS, and AES

Surface Analysis Spotlight: TOF-SIMS

by Jacob Schmidt Staff Scientist

Increased global energy demands and environmental concerns have driven the need for next-generation energy storage, requiring novel battery designs with excellent performance and stability at a lower cost with improved safety. These novel battery devices are complex, multi-layered systems with interfaces including the Cathode Electrolyte Interphase (CEI) and the Solid Electrolyte Interphase (SEI). Many chemical problems can occur within these interfaces, for example, unwanted redox and corrosion reactions at the CEI or lithiation and dendrite growth at the SEI. Understanding and preventing these unwanted reactions is paramount in the development of novel battery technologies.

Surface analysis techniques such as TOF-SIMS, XPS, and AES, can be used to characterize the many layers within a battery to verify chemical concentrations and conduct failure analysis on components. Combining these techniques provides a holistic understanding of the battery system. TOF-SIMS offers ppm-level insight into molecular bonding and structural composition as well as depth profiling, which was used to identify buried defects¹ (Figure 1). AES provides high-spatial-resolution spectra, images, and maps for nm-range analysis of defects and small sample features² (Figure 2). Operando XPS monitors battery performance in real time by tracking chemical state changes as they occur during charging and discharging cycles, or while under constant current density³ (Figure 3).

Figure 1 – TOF-SIMS depth profile of an All-Solid-State Battery showing an unintended interlayer between the LiPON and LCoO2 layers, formed during the manufacturing process	Figure 2 – AES chemical state imaging (left) and the spectral shift during oxidation (right) showing the formation of Li dendrites in a Li ion battery.

Figure 3 – Operando XPS analysis of a Li ion battery allows for the monitoring of LiF formation while applying a constant current density.

For more information on how surface analysis instrumentation is used in research, please attend the 24^th International Conference on Secondary Ion Mass Spectrometry (SIMS 24) where Dr. Jacob Schmidt will present a poster on "Insights Into Battery Chemistry Using TOF-SIMS, XPS, and AES."

1. Iida, S.-i.; Terashima, M.; Mamiya, K.; Chang, H.-Y.; Sasaki, S.; Ono, A.; Kimoto, T.; Miyayama, T. J. Vac. Sci. Technol. B, 2021, 39(4), 044001.
2. N. Ishida, D. Fujita, Journal of Electron Spectroscopy and Related Phenomena, 186, 2013
3. Benayad, A.; Morales-Ugarte, J.E.; Santini, C.C.; Bouchet, R. J. Phys. Chem. A 2021, 125, 4, 1069–1081.