Lithium-ion batteries based on tin (Sn) anode have the advantage of high energy density at a reasonable cost. However, their commercialization suffers from rapid capacity fading caused by active material aggregation, huge volumetric change, and continuous formation/deformation of solid-electrolyte interphase (SEI). Herein, we report an anode made of nanosized metallic Sn particles embedded in a hierarchically porous sulfur-doped graphene foam (Sn@3DSG). In this design, the sulfur-doped graphene foam provides abundant active defect sites to facilitate the rapid lithium-ion diffusion from outside to inside the Sn nanoparticles. Meanwhile, the hierarchical pores resulting from the self-assembly of graphene and evaporation of nanosized metallic Zn provide sufficient space to hold the volumetric changes of Sn. Owing to these merits, the as-prepared Sn electrode exhibits an excellent lithiated capacity (1272 mA h g-1 at 200 mA g-1) and high-rate performance (345 mA h g-1 at 2000 mA g-1) in the LiFSI-based electrolyte. It is also discovered that a LiF-Li3N-rich SEI layer is formed on the surface of the Sn electrode in a LiFSI-based electrolyte, which is beneficial for enhancing the electrode's cycling stability. Our work shows great promise of composite Sn anodes for future high-energy-density lithium-ion batteries.
Keywords: LiFSI-based electrolyte; Sn anode; lithium-ion battery; solid-electrolyte interphase; sulfur-doped graphene.