Anode-electrolyte interface in lithium-ion batteries investigated by liquid phase transmission electron microcopy: Achievements, challenges, and future directions

The electrochemical performance of lithium-ion batteries (LIBs) is strongly influenced by the complex interactions at the anode-electrolyte interface, which directly affect the battery's efficiency, cycle life, and safety. Liquid-phase transmission electron microscopy (LP-TEM) has become a key technique for in situ observations of the dynamic processes occurring at this interface. Numerous studies have investigated these complex interfacial processes, often complementing each other, occasionally overlapping, and sometimes presenting contradictory findings. In this work, we provide an overview of the key processes occurring at the anode-electrolyte interface, the most widely used LP-TEM setup to study them, and the current state of knowledge derived from these studies. Furthermore, we discuss the existing challenges, highlight areas that require further investigation, and propose future research directions aimed at overcoming these limitations to deepen our understanding of electrochemical mechanisms at the anode-electrolyte interface in LIBs.