Cryo‐Electron Tomography of Highly Deformable and Adherent Solid‐Electrolyte Interphase Exoskeleton in Li‐Metal Batteries with Ether‐Based Electrolyte

作者：Bing Han, Xiangyan Li, Qi Wang, Yucheng Zou, Guiyin Xu, Yifeng Cheng, Zhen Zhang, Yusheng Zhao, Yonghong Deng, Ju Li, Meng Gu · 发表于：Advanced Materials · 年份：2021 · DOI：10.1002/adma.202108252 · 被引用次数：46 · 研究领域：Advancements in Battery Materials、Advanced Battery Materials and Technologies、Advanced Battery Technologies Research

Abstract The 3D nanocomposite structure of plated lithium (Li Metal ) and solid electrolyte interphases (SEI), including a polymer‐rich surficial passivation layer (SEI exoskeleton) and inorganic SEI “fossils” buried inside amorphous Li matrix, is resolved using cryogenic transmission electron microscopy. With ether‐based DOLDME‐LiTFSI electrolyte, LiF and Li 2 O nanocrystals are formed and embedded in a thin but tough amorphous polymer in the SEI exoskeleton. The fast Li‐stripping directions are along or , which produces eight exposed {111} planes at halfway charging. Full Li stripping produces completely sagging, empty SEI husks that can sustain large bending and buckling, with the smallest bending radius of curvature observed approaching tens of nanometers without apparent damage. In the 2nd round of Li plating, a thin Li BCC sheet first nucleates at the current collector, extends to the top end of the deflated SEI husk, and then expands its thickness. The apparent zero wetting angle between Li BCC and the SEI interior means that the heterogeneous nucleation energy barrier is zero. Due to its complete‐wetting property and chemo‐mechanical stability, the SEI largely prevents further reactions between the Li metal and the electrolyte, which explains the superior performance of Li‐metal batteries with ether‐based electrolytes. However, uneven refilling of the SEI husks results in dendrite protrusions and some new SEI formation during the 2nd plating. A strategy to form bigger...