Fe3Se4 nanoparticles confined in hollow carbon nanocages for high-performance sodium-ion batteries

Abstract

Fe3Se4 nanoparticles confined in hollow and self-supported carbon nanocages are synthesized for the first time through facile Fe3O4 nanospheres precursor etching couple with a following selenization process. The as-obtained Fe3Se4@C nanocages exhibit excellent sodium storage performance as sodium-ion battery anodes. The remarkable electrochemical properties are attributed to the high specific capacity of Fe3Se4 on top of the specially-designed nanocage architecture, in which the sufficient internal void space between the Fe3Se4 nanoparticles and the carbon shell accommodates the volume variation of Fe3Se4 to avoid and deforming the carbon shell as well as the entire composite nanostructure. The presence of the highly conductive carbon shells facilitate fast electron and Na+ ion transportation to promote continuous sodiation and desodiation. Benefiting from this unique nanostructure, the composite delivers a stable high specific capacity of 544.1 mAh g−1 at 200 mA g−1 after 100 charge/discharge cycles. Furthermore, a stable capacity of 402.2 mAh g−1 is retained at 2000 mA g−1 after 200 cycles. Meanwhile, a high specific capacity of 328.7 mAh g−1 is achieved at the extraordinary current density of 5000 mA g−1, manifesting an outstanding sodium storage performance.