Surface Coating Constraint Induced Anisotropic Swelling of Silicon in Si–Void@SiOx Nanowire Anode for Lithium‐Ion Batteries

Here a simple and an environmentally friendly approach is developed for the fabrication of Si–void@SiO x nanowires of a high‐capacity Li‐ion anode material. The outer surface of the robust SiO x backbone and the inside void structure in Si–void@SiO x nanowires appropriately suppress the volume expansion and lead to anisotropic swelling morphologies of Si nanowires during lithiation/delithiation, which is first demonstrated by the in situ lithiation process. Remarkably, the Si–void@SiO x nanowire electrode exhibits excellent overall lithium‐storage performance, including high specific capacity, high rate property, and excellent cycling stability. A reversible capacity of 1981 mAh g −1 is obtained in the fourth cycle, and the capacity is maintained at 2197 mAh g −1 after 200 cycles at a current density of 0.5 C. The outstanding overall properties of the Si–void@SiO x nanowire composite make it a promising anode material of lithium‐ion batteries for the power‐intensive energy storage applications.