Rational design of dual-functional core-shell SiO_x/C@MoO₂ with hierarchical structure for enhanced lithium storage

SiO_x is considered as a highly promising anode material for lithium-ion batteries (LIBs) owing to its exceptional theoretical capacity, abundant reserves, and low cost. However, the low intrinsic electrical conductivity and significant volume variety during cycling hindered its practical application. In this work, a novel SiO_x/C@MoO₂ composite with a dual-functional core-shell structure is successfully fabricated by a spray drying and carbonization techniques. In this composite, asphalt-derived carbon uniformly coated on SiO_x provided an internal conductive carbon framework. The MoO₂ nanoparticles provide abundant active sites for Li⁺ storage and act as a robust protective layer, which effectively mitigates the volume expansion issue. Furthermore, the synergistic effect between MoO₂ and the carbon layer can also inhibit the conversion of organic lithium salts to Li₂CO₃ during SEI formation, reduce irreversible side reactions, and thus construct a more stable SEI film. The as-prepared SiO_x/C@MoO₂ exhibits a high ICE (76.8%) and stable capacity (508 mAh g^-1 after 1000 cycles at 1.0 A g^-1). In addition, the SiO_x/C@MoO₂ //LiFePO₄ full cell also shows a high capacity retention of 63.8% after 100 cycles. This work provides a novel insight into the rational design of core-shell structures for multifunctional silicon-based anode materials.