On the Redox Activity of the Solid Electrolyte Interphase in the Reduction/Oxidation of Silicon Nanoparticles in Secondary Lithium Batteries

Chemical and structural modifications occurring in homogeneous crystalline Si nanoparticles (NPs) used as anode material Li cells are investigated. State‐of‐the‐art high‐resolution scanning transmission electron microscopy coupled with energy loss spectroscopy resolved at the nanoscale is exploited. It directly highlighted by spectromicroscopy that, above 0.1 V versus Li, electrochemical activity of electrodes involves a complex interplay between incorporation, electrolyte degradation, reduction/oxidation. These redox processes occur upon cycling through partially reversible reactions mediated solid interphase. Overall, SiO 2 amorphous layer forms oxidized NPs interface electrolyte: this oxide shell dissolves reduction to give CO 3 Si. cores therefore eroded their outer layers involved oxygen shifting mechanism interface, whereas unreacted accumulates cycle‐by‐cycle. findings extend comprehension pulverization batteries.