Honeycomb-Structured MoSe₂ /rGO Composites as High-Performance Anode Materials for Sodium-Ion Batteries

Sodium-ion batteries are a promising substitute for lithium batteries due to the abundant resources and low cost of sodium. Herein, honeycomb-shaped MoSe₂ /reduced graphene oxide (rGO) composite materials are synthesized from graphene oxide (GO) and MoSe₂ through a one-step solvothermal process. Experiments show that the 3D honeycomb structure provides excellent electrolyte penetration while alleviating the volume change during electrochemical cycling. An anode prepared with MoSe₂ /rGO composites exhibits significantly improved sodium-ion storage properties, where a large reversible capacity of 215 mAh g^-1 is obtained after 2700 cycles at the current density of 30.0 A g^-1 or after 5900 cycles at 8.0 A g^-1 . When such an anode is paired with Na₃ V₂ (PO₄ )₃ to form a full cell, a reversible specific capacity of 107.5 mAh g^-1 can be retained after 1000 cycles at the current of 1.0 A g^-1 . Transmission electron microscopy, X-ray photoelectron spectroscopy and in situ X-ray diffraction (XRD) characterization reveal the reversible storage reaction of Na ions in the MoSe₂ /rGO composites. The significantly enhanced sodium storage capacity is attributed to the unique honeycomb microstructure and the use of ether-based electrolytes. This study illustrates that combining rGO with ether-based electrolytes has tremendous potential in constructing high-performance sodium-ion batteries.