Real‐Time Investigation of Interfacial Evolution in Electrochemical Energy Storage Systems via EQCM

ABSTRACT Understanding the structure and formation process of the electrode/electrolyte interface (EEI) is crucial for electrochemical energy storage research. The electrochemical quartz crystal microbalance (EQCM) has evolved into a powerful in situ characterization tool capable of resolving complex electrochemical interfacial processes. This review comprehensively summarizes recent progress in EQCM and its derivative techniques, including EQCM with dissipation monitoring and alternating current electrogravimetry (ac‐EQCM) for investigating the EEI. Special emphasis is placed on the role of EQCM in unraveling charge storage mechanisms, evaluating structural stability and failure modes, and monitoring interfacial reactions, including the formation and dynamics of solid‐electrolyte interphases. Additionally, recent breakthroughs in the joint use of EQCM with complementary techniques, such as spectroscopy and nuclear magnetic resonance, are discussed to highlight its unique advantages in multi‐dimensional analysis of interfacial mass, structural, and mechanical evolution. Finally, the future development of EQCM is explored, emphasizing its enduring significance in accelerating the development of next‐generation energy storage devices.