Three-dimensional MoO2@few-layered MoS2 covered by S-doped graphene aerogel for enhanced lithium ion storage

Highlights: • MoO₂@few-layered MoS₂ covered by S-doped graphene aerogel is prepared. • MO/MS/SG aerogel exhibits enhanced electrochemical performance. • S doping in graphene increases the defects and active sites. • MoO₂ coated by few-layer MoS₂ can promote good dispersion of MoO₂. MoO₂ with low electrical resistivity and high specific capacity as anode for lithium ion batteries is hindered because of its large volume variation during Li⁺ insertion/extraction process, which leads to fast capacity fading. Herein, three-dimensional (3D) core-shell MoO₂@few-layered MoS₂ covered by S-doped graphene (MO/MS/SG) aerogel has been fabricated through hydrothermal reaction and freeze-drying process together with sulfidation. MoO₂ nanoparticles coated by few-layer MoS₂ can promote good dispersion of MoO₂ nanoparticles and avoid the restacking of MoS₂. S doping in graphene can increase the defects and active sites. S-doped graphene aerogel as flexible framework and conductive network not only provides the transmission path for ions and electrons, but also maintains the structural integrity of electrode during cycles. Core-shell MoO₂@few-layer MoS₂ hybrid well-dispersed in S-doped graphene matrix buffers the volume changes during cycles and contributes to high reversible capacity. Free-standing electrode without binder and current collector prevents the separation of electrode materials from current collector during cycles. Benefitting from the unique structures, the MO/MS/SG aerogel as anode for lithium ion battery exhibits high reversible capacities of 683 mAh g⁻¹ at 0.1 A g⁻¹ after 100 cycles and 533 mAh g⁻¹ at 0.5 A g⁻¹ after 350 cycles together with excellent rate capability. This work demonstrates the potential application of the Mo-based materials in lithium ion batteries.