“…In the past ten years, researchers have employed a variety of advanced spatial-, time-, and energy-resolved characterization tools, in combination with theoretical simulations, to characterize the SEI composition and structure, with the aim of updating the knowledge of SEI chemistry. − For example, with the successful application of cryogenic transmission electron microscopy (cryo-EM), a number of literatures reported that the SEI exhibits a so-called plum pudding model (Figure c), in which an amorphous organic polymer matrix (termed “pudding”) was embedded with inorganic crystalline (known as “plums”). , Additionally, our group proposed an ultrasmooth ultrathin SEI for Li metal, which has proven to bear alternating organic–inorganic multilayered structure by employing atomic force microscope (AFM)-based indentation technique (Figure d). , Despite the variations in the detailed structure, the latest understanding of SEI remains fundamentally consistent with classical mosaic and layered models. Essentially, a precise knowledge regarding the SEI composition and structure as well as an accurate and comprehensive understanding of the formation and evolution mechanism and roles of the SEI in anode processes is still lacking.…”