Mechanistic Study of Electrode Materials for Rechargeable Batteries beyond Lithium Ion by In-situ Transmission Electron Microscopy
Understanding the fundamental mechanisms of advanced electrode materials at the atomic scale during the electrochemical process is condemnatory to develop the high-performance rechargeable batteries. The complex electrochemical reactions involved inside a running battery, which cause intensive structural and morphological changes in electrode materials, have been explored to a certain extent by the introduction of real-time characterization techniques. In-situ transmission electron microscopy (TEM) is one of the most noteworthy diagnostic techniques to understand and monitor the dynamic electrochemical processes because of its atomic-scale resolution and real-time monitoring, which can provide information about the chemical and physical characteristics. In this review, the current progress in the development of electrode materials using in-situ TEM for rechargeable batteries beyond lithium ion is summarized. First, the various battery designs used for in-situ TEM and their challenges are elaborated. Afterward, we systematically summarize the basic science and fundamental reactions including phase transformation and electrode/electrolyte interfaces in electrode materials for heavier alkali ion (sodium, potassium calcium and magnesium) batteries (H-AIBs). Particularly, the real-time insights into three types of electrochemical mechanisms: intercalation, alloying, and conversion reactions is elaborated. Moreover, in-situ electrode chemistry in lithium sulfur batteries (Li-S) and alkali-metal oxygen batteries (AOBs) including lithium, sodium and potassium oxygen batteries, all-solid-state batteries (ASSBs) is also discussed. Finally, we provide the summary and future perspective of in-situ TEM in rechargeable batteries along with the most feasible electrode designing.