Correlative Microscopy Analysis for Battery Materials

Abstract

Lithium batteries (LB) are in high demand for a diverse range of applications, such as automotive industry, consumer electronics, wearable and medical devices, grid storage, etc. Each application demands a specific set of performance advantages, such as high capacity and/or energy density, long cycle life, superior electrochemical stability. Therefore, there is no one-size-fits-all for a LB chemistry and its form factor. Battery performance advantages rely on optimization of the battery components, including active materials, electrolyte, separator, binder system, and current collectors. For meaningful device optimization, electrochemical battery testing needs to be combined with a deep understanding of the material and device microstructure. Physical and chemical characterization on the material- and electrode-level is needed to establish root-cause relationships with battery performance. Properties of the interfaces between layers of the battery components often define the device characteristics. Critical information is usually buried beneath the surface of a material specimen or encapsulated in a closed-form device. Microstructural defect identification in the battery needs to be followed by a targeted defect study. Different battery form factors and chemistries make it hard to streamline root-cause analysis.Recently, a commercial focused-ion beam scanning electron microscope was developed with an integrated fs-laser mill attached to the load lock of the microscope, opening the door to new and more powerful analysis approaches in energy materials research. Applications include rapid access to deeply buried structures for high resolution imaging and analytics, large area cross-section preparation, and massive material ablation for sample preparation of structures; e.g. FIB-SEM tomography, TEM, APT, or X-ray nanoCT. Additionally, each of these methods may be correlatively guided by prior imaging, with techniques like 3D X-ray microscopy (XRM), to enable targeted analysis and preparation. The non-destructive nature of 3D XRM makes it an ideal tool for microstructural defect identification in LB. Laser mill allows researchers to combine non-destructive X-ray defect identification with electron microscopy methods for targeted defect characterization. This approach can be used for various battery types and form factors.By combining the laser mill with 3D X-ray microscopy, this platform enables comprehensive analysis of energy materials at the nanoscale. We illustrate these concepts with application examples, and use cases demonstrating the utility of the approach.