The role of ex situ solid electrolyte interphase in lithium metal batteries

Lithium metal anode (LMA) is arising as a strong anode candidate for the next-generation high energy density lithium metal batteries (LMBs) due to their high theoretical capacity, low mass density, and low redox potential. However, the practical application of LMA is hindered due to its inherent problems such as infinite volume expansion and the highly reactive nature. The infinite volume expansion issues lead to the pulverization of the Li electrode and the formation of unstable solid electrolyte interphase (SEI), resulting in Li dendrite growth. The hyperactive nature of Li consumes both Li and electrolyte, resulting in low Coulombic efficiency (CE). As a result, there is a challenge in the safety concern of the battery and poor cycling life span. Here, we provided a summary of the recent development of facile and low-cost ex situ-derived SEI. The commonly used physical and chemical deposition technique for the development of stable ex situ-based SEI can revive the LMA. We highlighted the preparation method, electrochemical performance, as well as some drawbacks of ex situ-based SEIs to provide readers a concise overview of the field for developing novel, effective, low-cost, and stable ex situ-based artificial SEIs.