A Brief Review on Solid Electrolyte Interphase Composition Characterization Technology for Lithium Metal Batteries: Challenges and Perspectives

Lithium metal batteries (LMB) are recognized as the most promising high-energy-density energy storage devices. However, its large-scale commercial applications are seriously hampered by the poor cycling stability and potential safety issues. Solid electrolyte interphase (SEI) acts a dominant role in influencing the regulation of Li deposition and overall performance of LMBs, but the composition as well as the evolution of SEI remain quite elusive. Advanced characterization methods and operando monitoring techniques are urgently required. Herein, in this perspective, we first briefly introduce the development history of SEI research and the SEI formation mechanisms as well as the common known components of SEI. Then, we focus on several recent advanced technologies for SEI characterization and monitoring, and the corresponding study cases will be presented. In the end, perspectives including the future investigation directions, the in situ characterization methods, and the component-performance associated model are proposed. We believe that this timely review will help to give a comprehensive understanding on the up-to-date SEI characterization tools.