Dual‐Layer Sulfur‐Doped Artificial Solid‐Electrolyte Interphase on SiO Anodes Boosts the Performance of Lithium‐Ion Batteries

Abstract Silicon monoxide (SiO) is a highly promising anode material for lithium‐ion batteries (LIB) because of its high theoretical specific capacity. However, its intrinsically poor electrical conductivity and the inevitable formation of an electrochemically inactive solid electrolyte interphase (SEI) severely limit battery performance. Here, we propose a scalable wet ball‐milling strategy to construct a dual‐layer core‐shell SiO‐based composite. The inner layer comprises a hybrid conductive network of carbon nanotubes (CNTs) and reduced graphene oxide (rGO), significantly improves electron transport pathways. The outer shell is a dense sulfur‐doped cyclized polyacrylonitrile (ScPAN), derived from a polymer precursor, which effectively mitigates volume expansion, stabilizes the SEI, and prevents direct SiO‐electrolyte contact. This unique architecture yields the SiO@rGO‐CNT@ScPAN composite, used as the active anode material in LIBs. Battery tests show an initial coulombic efficiency of 81.48% at 0.1 A g −1 , along with excellent cycling stability and rate performance. Notably, it retains 901.7 mAh g −1 after 250 cycles at 1 A g −1 , with 94.37% capacity retention and coulombic efficiency above 99%. Furthermore, a full cell with a NCM811 cathode exhibits stable cycling over 150 cycles at 0.2 C, demonstrating the practical viability of this composite design for next‐generation LIBs.