Webinar Recap: Characterizing Li-Ion Battery Materials using FIB-SEM with integrated ToF-SIMS

An Outlook into the future of battery research

In our latest webinar on February 16th, 2024, Tomáš Šamořil, Ph.D., from TESCAN Group showcased the powerful synergy between FIB-SEM and ToF-SIMS, greatly enhancing lithium-ion battery research.

We thank everyone who participated for enriching this event through a lively discussion. It is through the combined efforts of our community that we are able to gain deeper insights into the structure and chemistry of battery materials, pushing forward the boundaries of performance, longevity, and sustainability.

Missed out on the webinar? Worry not, we have compiled the answers to the ensuing questions to ensure you don't miss out on the valuable insights shared during the session.

Question: What do you do if the samples are charging in ToF-SIMS?

Answer: To mitigate charging during ToF-SIMS analysis, it is advisable to rapidly scan the analyzed area using SEM under conditions optimized for the charging level observed. Alternatively, employing a Flood Gun, which provides an intensive and broad electron beam, can effectively counteract charging, though it is typically suitable for larger areas.

Question: Have you used any ions other than Xe for ToF-SIMS? Oxygen, perhaps?

Answer: TESCAN utilizes Xe plasma FIB on its high-vacuum FIB-SEM platform, predominantly for its advantages across various applications, including battery research. Oxygen is generally avoided, especially in battery contexts, due to its potential to react with the materials under study, which could compromise the analysis.

Question: How do you detect gas in a battery cell?

Answer: Detecting gas within a battery cell using a FIB-SEM system requires overcoming the challenges of high vacuum conditions and often necessitates disassembling the cell. Employing cryo conditions can mitigate gas release during analysis. For in-depth studies on gas evolution within cells, non-destructive methods like micro-CT provide valuable insights, as they allow for the observation of gas formation without damaging the cell.

Question: Is it possible to perform in situ imaging of batteries, including charging/discharging, inside the microscope's chamber?

Answer: While in situ imaging poses challenges for traditional lithium-ion batteries due to electrolyte evaporation under vacuum, it is feasible for batteries with solid-state electrolytes. Such analyses offer valuable insights into battery behavior and have been documented in scientific publications.

Question: Given that TOF-SIMS is a destructive method, can it be used for a series of experiments on the same specimen?

Answer: The possibility of conducting repeated TOF-SIMS analyses on the same region depends on the specifics of the experiment and the area's exposure to FIB. For instance, electrode mapping may allow for subsequent analyses after minimal material removal, but depth profiling requires identifying new regions for each assessment to ensure comprehensive and representative results.

Question: What is the spatial resolution of TOF-SIMS for imaging and depth analysis?

Answer: The spatial and depth resolution of TOF-SIMS can reach approximately 50 nm and 3 nm, respectively. Achieving high resolution depends critically on the FIB conditions, including the accelerating voltage and ion beam current. Optimal conditions often involve high voltage and low current settings, particularly for detailed examinations of electrode cross-sections.

Question: How do you achieve quantification in TOF-SIMS?

Answer: Quantification in TOF-SIMS typically involves using known standards for comparative analysis, which helps correlate signal intensity with concentration. Given the complexities of battery materials, alternative approaches may leverage theoretical models to interpret mass spectral data, providing a more nuanced understanding of the sample composition.

Question: What conditions enhance high-resolution imaging?

Answer: High-resolution imaging, particularly for observing surface details of battery materials, benefits from the advanced capabilities of SEM technology, like the BrightBeam SEM column. Adjusting the accelerating voltage and beam current, especially at lower settings, can significantly improve resolution and surface detail visibility.

Question: How do you improve resolution for milling and imaging solid-state electrolytes, considering they are typically insulators?

Answer: Addressing charging and drift issues during imaging of insulating materials like solid-state electrolytes involves careful adjustment of imaging conditions. Utilizing lower accelerating voltages and beam currents can reduce charging effects, enhancing image stability and resolution during SEM observations.

Question: What is the milling rate for a large cross-section of the NMC cathode?

Answer: Milling a 1 mm-wide cross-section through an NMC cathode, inclusive of silicon mask placement, typically takes around 3.5 hours. The process duration can vary depending on the desired quality of the cross-section surface.

Question: What is the mass resolution of ToF-SIMS offered by TESCAN?

Answer: TESCAN provides two ToF-SIMS configurations: the C-TOF with a mass resolution of around 800 and the H-TOF with a higher resolution of 3500. The latter's superior mass resolution facilitates clearer distinction between spectral peaks, allowing for more detailed chemical analysis.

Question: How long does it take to prepare a large electrode cross-section with FIB?

Answer: Preparing a 250 µm-wide cross-section of a graphite anode, including protective mask placement, typically requires about 2 hours. This duration may be shorter for cathode materials, which are generally softer than graphite anodes.

If you're keen to further advance your understanding of battery materials analysis, we warmly invite you to our next webinar session on April 25th, 2024. Dean Miller Ph.D., Principal Scientist at TESCAN USA and Vick Singh, Senior Vice President of Technology at Dragonfly Energy Corp. will lead the discussion on Addressing Challenges in Lithium-Ion Battery Development and Production with Electron Microscopy and X-ray Microtomography, offering invaluable insights into cutting-edge research methodologies during next WAS conference.

Find all the information here (this link will be activated soon)

← See all posts