Preparation of double‐shell Si@SnO 2 @C nanocomposite as anode for lithium‐ion batteries by hydrothermal method

Abstract Silicon is one of the most promising anode materials for lithium‐ion batteries (LIBs), but it suffers from pulverization and hence poor cycling stability due to the large volume variation during lithiation/delithiation. The core–shell structure is considered as an effective strategy to solve the expansion problem of silicon‐based anodes. In this paper, the double‐shell structured Si@SnO 2 @C nanocomposite with nano‐silicon as the core and SnO 2 , C as the shells is synthesized by a facile hydrothermal method. Structural characterization shows that Si@SnO 2 @C nanocomposite is composed of crystalline Si, crystalline SnO 2 and amorphous C, and the contents of them are 42.1 wt%, 37.8 wt% and 20.1 wt%, respectively. Transmission electron microscope (TEM) observations confirm the double‐shell structure of Si@SnO 2 @C nanocomposite, and the thicknesses of the SnO 2 and C layers are 20 and 7 nm. The Si@SnO 2 @C electrode exhibits a high initial discharge capacity of 2777 mAh·g −1 at 100 mA·g −1 and an excellent rate capability of 340 mAh·g −1 at 1500 mA·g −1 . The outstanding capacity retention is 50.2% after 300 cycles over a potential of 0.01 to 2.00 V (vs. Li/Li + ) at 500 mA·g −1 . The resistance of solid electrolyte interphase (SEI) film ( R f ) and charge transfer resistance ( R ct ) of Si@SnO 2 @C are 7.68 and 0.82 Ω, which are relatively smaller than those of Si@C (21.64 and 2.62 Ω). It is obviously seen that the SnO 2 shell can reduce the charge transfer resistance, leading to high ion and electron transport efficiency in the Si@SnO 2 @C electrode. The incorporation of SnO 2 shell is attributed to the enhanced rate capability and cycling performance of Si@SnO 2 @C nanocomposite.