In Situ TEM Characterization of Battery Materials

Transmission electron microscopy (TEM) is an indispensable analytical technique in materials research as it probes material information down to the atomic level and can be utilized to examine dynamic phenomena during material transformations. In situ TEM resolves transient metastable states via direct observation of material dynamics under external stimuli. With innovative sample designs developed over the past decades, advanced in situ TEM has enabled emulation of battery operation conditions to unveil nanoscale changes within electrodes, at interfaces, and in electrolytes, rendering it a unique tool to offer unequivocal insights of battery materials that are beam-sensitive, air-sensitive, or that contain light elements, etc. In this review, we first briefly outline the history of advanced electron microscopy along with battery research, followed by an introduction to various in situ TEM sample cell configurations. We provide a comprehensive review on in situ TEM studies of battery materials for lithium batteries and beyond (e.g., sodium batteries and other battery chemistries) via open-cell and closed-cell in situ TEM approaches. At the end, we raise several unresolved points regarding sample preparation protocol, imaging conditions, etc., for in situ TEM experiments. We also provide an outlook on the next-stage development of in situ TEM for battery material study, aiming to foster closer collaboration between in situ TEM and battery research communities for mutual progress.