In situ transmission electron microscopy (TEM) electrochemistry with high-resolution characterization of morphology and microstructure is a powerful and practical technique to observe and analyze the lithiation and delithiation process of Li ions in the cathode and anode for comprehensively understanding the performance of Li-ion batteries ( LIB), the formation of a solid electrolyte interphase ( SEI), and the aging process during the investigation of LIBs. This review mainly focuses on the development and achievements of in situ TEM electrochemical techniques in investigating the mechanism of LIBs in recent years. Three types of in situ TEM electrochemical holders that are used commonly in the characterization of LIBs are presented. A calculation method for quantitative determination of the lithium diffusion coefficient ( D-Li) in electrodes with in situ TEM electrochemical technique is also mentioned. Finally, the challenges, limitations, and future work for during application of the in situ TEM-electrochemistry technique are further discussed and reviewed from the perspective of morphology, influence of electron radiation on the decomposition of electrolyte, configuration of electrode, and determination of D-Li. (C) The Author( s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License ( CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@ electrochem. org. All rights reserved.