The use of microscopy to characterize Li-ion batteries (and fuel cells) has grown immensely in recent years. Coupled with advancements in modeling and simulation techniques, this approach offers a unique perspective on Li-ion battery cell design, operational characteristics, and establishes the linkage between performance and microstructure. Based on the work from Bruggeman and others, many historical models have centered around assumptions of microstructure ideality, such as spherical geometries of electrode particles, geometric isotropy of fluid- and pore-transport pathways (e.g., porosity, tortuosity, and constrictivity), and uniformity of binder distribution. By employing various imaging techniques, recent results have demonstrated that these assumptions are far from accurate, and that discrepancies from ideality can have profound effects on battery performance and durability. With the advent of modern 3D imaging techniques, such as X-ray microscopy (XRM) and focused ion beam coupled scanning-electron microscopy (FIB-SEM), the past decade has witnessed a startling increase in the numbers of publications related to microstructure characterization and the supportive modeling techniques.

Attendees to this short course will leave with a solid foundation in microstructure characterization, with a general understanding of each modality that has shown significant utility for battery imaging. They will also understand what software tools exist in support of these efforts and various lighthouse facilities with access to the complete suites of available tools. The aim of the course is to be educational, informative, and engaging, with discussions planned amongst the attendees and organizers regarding unique opportunities that may exist for applying the techniques introduced.

Course outline

• Introduce various techniques for imaging Li-ion batteries, including light-, electron-, and X-ray microscopy.
• Discuss chemical characterization approaches, using techniques such as energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy.
• Provide a historical survey of the foundations laid by various experts in the field.
• Demonstrate cutting-edge applications of the imaging techniques introduced to characterizing battery cells in 2D, 3D, and 4D.
• Survey the available tools for performing this analysis, ranging from freeware packages, such as Fiji / ImageJ to commercial solutions, such as ORS VisualSi Advanced and Math2Market GeoDICT.
• Review recent progress in image-based characterization and discuss the opportunities for further advancements in this field.
• Discuss experimental and modelling challenges and various routes toward overcoming them