Elucidating the interfacial evolution and anisotropic dynamics on silicon anodes in lithium-ion batteries

Silicon (Si) has been considered as one of the most promising anodes in secondary high-energy rechargeable lithium-ion batteries (LIBs) owing to its high theoretical specific capacity and abundant reserves, whereas it suffers from an unstable solid electrolyte interphase (SEI) film and dramatic volume expansion. Herein, in situ electrochemical atomic force microscopy (AFM) and visual videos were used to reveal the interphasial properties of SEI film and anisotropic dynamics upon lithiation/delithiation processes on the single-crystalline Si electrodes with different crystal plane orientations. Lithiation of Si (111) prefer to grow along the <121> direction in the XY plane with the shape of oriented rods, in contrast, that of Si (100) form cone-like structure with the axial direction of <100> perpendicular to the (100) surface. Quantitative dynamic processes elucidate the preferable reversibility in Si (111) system, revealing the corresponding structure-reactivity correlations.