F-Center-Mediated Formation of Metallic Li from Solid Electrolyte Interphases under High-Energy Electron-Beam...

The solid electrolyte interphase (SEI) plays a critical role in governing interfacial kinetics and maintaining anode stability during electrochemical cycling. As such, elucidating the structure-property relationships of the SEI is essential but also highly challenging due to its inherent sensitivity. Recent advances in electron microscopy have greatly facilitated these efforts by enabling nanoscale structural characterization. However, the fundamental response of sensitive SEI to high-energy electron-beam exposure remains largely unexplored. Here the precipitation of metallic Li from SEI under electron-beam irradiation is revealed, which is driven by the accumulation of F-centers formed in Li₂O, the dominant inorganic SEI component. Remarkably, an electron beam can also trigger the reverse transformation of Li into Li₂O. The findings offer novel microstructural insights into the electron-beam-induced chemical dynamics of the SEI.