Quantifying the Morphology Evolution of Lithium Battery Materials Using Operando Electron Microscopy

With the increase in dependence on renewable energy sources, interest in energy storage systems has increased, particularly with solar cells, redox flow batteries, and lithium batteries. Multiple diagnostic techniques have been utilized to characterize various factors in relation to the battery performance. Electrochemical tests were used to study the energy density, capacity, cycle life, rate, and other related properties. Furthermore, it is critical to correlate the information collected from the characterization of materials to its properties while functioning for advanced batteries. In situ and operando electron microscopy methods are specifically designed to conduct such characterization, and analysis was found to be the best method to achieve that objective. However, the characterization information collected varies according to the types of electron microscopy techniques. Also, the use of complementary analytical techniques further provides a more comprehensive study of these different characterizations, giving insights into the morphology-performance relationship of battery materials and interfaces. Within this review, the focus is on in situ and operando electron microscopy characterization of battery materials, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), cryogenic transmission electron microscopy (Cryo-TEM), and three-dimensional (3D) electron tomography. This review aims to cover both advanced electron microscopy imaging techniques and their applications in the characterization of battery materials involving cathode, anode, and separator and solid electrolyte interphase (SEI). The review discusses a range of advanced electron microscopy techniques, including TEM, SEM, and atomic force microscopy, as well as associated analytical techniques such as energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy. The use of these techniques has led to significant advances in our understanding of battery materials, including the identification of new phases and structures, the study of interface properties, and the characterization of defects and degradation mechanisms. Future perspectives on these advanced electron microscopy techniques and opportunities are also discussed. Overall, this review highlights the importance of electron microscopy in battery research and the potential for these techniques to drive future advancements in the field.