Layer-by-layer stacked nanohybrids of N,S-co-doped carbon film modified atomic MoS2 nanosheets for advanced sodium dual-ion batteries

Abstract

Sodium dual-ion batteries (SDIBs) have received tremendous research attention due to their multiple advantages of environmental friendliness and high working voltages. However, the development of high-performance SDIBs still remains a daunting challenge, mainly due to the lack of robust anode materials with sufficient interlayer spacing for Na⁺ insertion/extraction. We here report a solvothermal method for the fabrication of coral-like nanohybrids that are constructed from layer-by-layer stacked nitrogen and sulfur co-doped carbon film modified atomic MoS₂ nanosheets (a-MoS₂NS@NSC_film). Comprehensive characterization demonstrates that a-MoS₂NS@NSC_film shows favorable electrochemical and structural properties for sodium ion storage, including significantly improved electrical conductivity and an expanded layer space of 0.95 nm thanks to carbon film modification, which favorably facilitate electron transfer and enhance Na⁺ diffusion kinetics, thus leading to an impressive capability for fast and high-capacity sodium storage. We further verify the practical application of a-MoS₂NS@NSC_film as an anode for SDIBs by coupling it with an expanded graphite (EG) cathode; this delivers a capacity of 40 mA h g⁻¹ with outstanding cycling stability and an extremely low capacity decay of 0.0056% per cycle after 5000 cycles at 10C.