Pyrolysis Induced Interphase and Structural Stabilization of Silicon‐Tin Disulfide/PAN Composite Electrode Materials for Li‐Ion Batteries

ABSTRACT C/Si/SnS ₂ composite anodes with 17 wt.% Si for lithium‐ion batteries were prepared via solid‐state reaction using SnCl ₄ ·5H ₂ O, elemental sulfur (S ₈ ), crystalline silicon and polyacrylonitrile (PAN). The obtained material contains silicon and tin di‐sulphide particles that are distributed within a carbonized, porous, PAN‐based matrix. The physicochemical characteristics and electrochemical performance of C/Si/SnS ₂ were compared to that of Si/SnS ₂ and pure Si. C/Si/SnS ₂ exhibited capacity retention of 520 mAh g ⁻¹ after 100 cycles at 0.1 C and rate‐capability performance with a capacity retention of 178 mAh g ⁻¹ at 2 C. The chemistry of the interfacial layer of C/Si/SnS ₂ was studied using post‐mortem XPS of the first discharge and charge steps. The qualitative and quantitative compositional analysis of the surface and inner SEIs revealed that Si and Si/SnS ₂ anodes developed thick, non‐uniform, oxidized SEI layers enriched with inorganic species, whereas C/Si/SnS ₂ formed a thin, homogenous, conductive SEI.