New dual-anions FeS_0.5Se_0.5@NC porous nanorods as advanced electrode materials for wide-temperature sodium-ion half/full batteries

The new N-doped carbon wrapped porous FeS_0.5Se_0.5 nanorods (FeS_0.5Se_0.5@NC) have been rationally designed using the FeOOH nanorod as a reaction template, poly-dopamine as the carbon source, combined with the subsequent sulfuration and selenization process. Due to the cooperative effect of dual-anion guided heterostructure, and the effective protection of highly conductive and uniform N-doped carbon layer, the FeS_0.5Se_0.5@NC as the new anode materials for room-temperature sodium ion batteries demonstrates remarkable sodium storage properties. When the current density is 0.5 A g⁻¹, the FeS_0.5Se_0.5@NC can deliver a satisfied specific capacity of 522.8 mAh g⁻¹ over 100 loops. Even at 5 A g⁻¹, it still shows outstanding long-period cycling stability (450 mAh g⁻¹ for 220 cycles). It also displays prominent rate capability (242.65 mAh g⁻¹ at 20 A g⁻¹). Even at a low temperature, the FeS_0.5Se_0.5@NC still shows good sodium storage properties. Except for the half-cells, the full cells also exhibit good electrochemical performances. Furthermore, various kinetic analysis and reaction mechanism of FeS_0.5Se_0.5@NC are investigated to analyze the excellent sodium storage properties. The synthesis strategy of FeS_0.5Se_0.5@NC can be adopted to prepare the other kinds of double anionic metal chalcogenides anode materials to explore the potential applications in different energy storage fields.