Recent Progress in Understanding Solid Electrolyte Interphase on Lithium Metal Anodes

Lithium metal batteries (LMBs) are one of the most promising candidates for next-generation high-energy-density rechargeable batteries. Solid electrolyte interphase (SEI) on Li metal anodes plays a significant role in influencing the Li deposition morphology and the cycle life of LMBs. However, a thorough understanding on the mechanisms of SEI formation and evolution is still inadequate. In this review, the progress in understanding structures, properties, and influencing factors of SEI, as well as efficient strategies of tailoring SEI are focused upon. First, the compositions, models, and recent progress in characterizing atomic structures of SEI are summarized. Second, the properties of SEI, including electronic conduction, ionic conduction, stability, and mechanical properties are elucidated. Structures and properties of SEI are greatly affected by multiple factors, thus interactions between these factors and SEI are systematically discussed. Correlations of SEI with Li deposition morphology, rate capability, and cycle life are further summarized. Moreover, efficient strategies of tailoring SEI with desired properties, including in situ SEI and ex situ SEI, are also reviewed. Finally, future directions, including in-operando techniques, multi-modality approaches for characterization of SEI, and artificial intelligence assisted understanding of correlations between electrolyte components and SEI properties are proposed.

Automated summary

The structure, properties, and influencing factors of SEI play a crucial role in the performance of lithium metal batteries. Efficient strategies for tailoring SEI involve understanding the composition, models, and properties of SEI, as well as the correlations between electrolyte components and SEI. Future directions include in-operando techniques, multi-modality approaches for SEI characterization, and artificial intelligence assisted understanding of SEI properties.