Tuning the stable interlayer structure of SiO_x-based anode materials for high-performance lithium-ion batteries

The significant volume expansion effect and unstable solid electrolyte interphase (SEI) film of SiO_x-based anode materials hinder their commercial development. Research has indicated that composite coating is a common strategy to address these crucial issues. This paper reports the preparation of SiO_x@TiO₂@C nanospheres with a unique interlayer structure using a sol–gel method combined with etching. In the preparation process, SiO_x nanospheres serve as the core, and the morphology and electrochemical performance of SiO_x@TiO₂@C are influenced by NaOH etching for different durations. With increasing etching time, SiO_x@TiO₂@C nanospheres with a suitable interlayer structure and sufficient gaps were obtained. This distinctive interlayer structure can mitigate the volume expansion of SiO_x, enhance the structural stability of the electrode material during repeated Li⁺ insertion/deinsertion processes, and improve cycling stability. When used as an anode material for lithium-ion batteries, the SiO_x@TiO₂@C with the best clearance exhibits a reversible capacity of 310.0 mAh g^-1 (600 cycles at 2.0 A g^-1), a high initial Coulombic efficiency (87%), and excellent cycling performance. This work paves the way for the development of SiO_x-based anode materials for high-performance lithium-ion batteries.