Core Insights - The article discusses a significant research study on the heterogeneous nature of lithium fluoride (LiF) in solid-electrolyte interphases (SEI), which challenges the long-held belief that components in the electrode interface layer are in pure phases [3][6] - The findings provide new explanations for rapid ion transport mechanisms in high-performance secondary batteries and offer important theoretical guidance for the design of high-performance electrolyte and electrode interface materials [3][6] Group 1 - The research team utilized 19F solid-state NMR technology to discover that LiF SEI exhibits rich spectral characteristics due to the formation of a limited LiF-LiH solid solution, consisting of hydrogen-rich (LiH1−yFy) and fluorine-rich (LiF1−xHx) phases [6] - The study confirmed that in high Coulomb efficiency electrolytes, the hydrogen-rich phase dominates, which can be explained by the superior ionic conductivity of the LiF-LiH solid solution compared to LiF alone [6] - As a proof of concept, the research demonstrated that a LiH1−yFy coating in lithium metal batteries shows significant advantages over a LiF coating, providing a new understanding of the component heterogeneity in SEI [6] Group 2 - The research was conducted by a collaborative team from Westlake University and Fudan University, with key contributors including Liu Xiangsi, Li Shuyang, Yuan Chen, and Zheng Bizhu as co-first authors, and Xiang Yuxuan, Song Yun, and Zhu Yizhou as corresponding authors [7]