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

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.