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

Withthe increase in dependence on renewable energy sources, interestin energy storage systems has increased, particularly with solar cells,redox flow batteries, and lithium batteries. Multiple diagnostic techniqueshave been utilized to characterize various factors in relation tothe battery performance. Electrochemical tests were used to studythe energy density, capacity, cycle life, rate, and other relatedproperties. Furthermore, it is critical to correlate the informationcollected from the characterization of materials to its propertieswhile functioning for advanced batteries. In situ and operando electronmicroscopy 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 accordingto the types of electron microscopy techniques. Also, the use of complementaryanalytical techniques further provides a more comprehensive studyof these different characterizations, giving insights into the morphology-performancerelationship of battery materials and interfaces. Within this review,the focus is on in situ and operando electron microscopy characterizationof battery materials, including transmission electron microscopy (TEM),scanning electron microscopy (SEM), cryogenic transmission electronmicroscopy (Cryo-TEM), and three-dimensional (3D) electron tomography.This review aims to cover both advanced electron microscopy imagingtechniques and their applications in the characterization of batterymaterials involving cathode, anode, and separator and solid electrolyteinterphase (SEI). The review discusses a range of advanced electronmicroscopy techniques, including TEM, SEM, and atomic force microscopy,as well as associated analytical techniques such as energy-dispersiveX-ray spectroscopy and electron energy loss spectroscopy. The useof these techniques has led to significant advances in our understandingof battery materials, including the identification of new phases andstructures, the study of interface properties, and the characterizationof defects and degradation mechanisms. Future perspectives on theseadvanced electron microscopy techniques and opportunities are alsodiscussed. Overall, this review highlights the importance of electronmicroscopy in battery research and the potential for these techniquesto drive future advancements in the field.