Cryo-Electron Microscopy for Unveiling the Sensitive Battery Materials.

Deep chemical and structural investigation of battery components is increasingly imperative for exploring new electrode materials and their performance iterations for the next-generation of energy storage devices with high energy density. This is particularly true in the research realm of lithium (Li) metal and its derivatives for the robust anode. Conventionally, both Li metal and its solid electrolyte interphase (SEI) layer are chemically reactive and sensitive to electron-beam irradiation, making the high-resolution observation difficult to perform at native environment. Recently, the emergence of cryo-electron microscopy (EM) has brought great opportunities to reveal the physicochemical properties of these energy materials. By means of cryo-EM, the high-resolution imaging of the samples at the nanometer or even atomic scale while maintaining their native state can be realized. Herein, the contributions of cryo-EM to the characterization of sensitive battery materials are focused on, which are tentatively classified as the following: the visualization of Li dendrites, inactive Li, and the discussion regarding electrode interface chemistry. The review concludes by providing several proposals for the development of cryo-EM in the future. It is hoped that this work will shed light on the in-depth understanding of battery materials for high-performance rechargeable batteries.