Nanostructured multicomponent metal selenide materials and their carbon composite materials have been studied as anode materials for sodium-ion batteries (SIBs). Hierarchically structured (Co1/3Fe2/3)Se2 nanofibers with fiber-in-tube nanostructures and (Co1/3Fe2/3)Se2-C composite nanofibers with filled structures were prepared by electrospinning with subsequent selenization. Selenization of the CoFe2O4 nanofibers formed rod-type (Co1/3Fe2/3)Se2 nanocrystals, and the tube-in-tube nanostructures of the nanofibers transformed into fiber-in-tube structures during this process. The discharge capacities of the hierarchically structured (Co1/3Fe2/3)Se2 nanofibers and (Co1/3Fe2/3)Se2-Se-C composite nanofibers were 594 and 512 mA h g-1 (for the 60th cycle at a current density of 0.3 A g-1), respectively, and their corresponding capacity retentions measured from the 2nd cycle were almost 100%. The reversible discharge capacity of the hierarchically structured (Co1/3Fe2/3)Se2 nanofibers decreased slightly from 585 to 497 mA h g-1 as the current density was increased from 0.1 to 5.0 A g-1. However, the reversible discharge capacity of the (Co1/3Fe2/3)Se2-Se-C composite nanofibers decreased from 543 to 359 mA h g-1 as the current density was increased from 0.1 to 5.0 A g-1. The uniquely structured (Co1/3Fe2/3)Se2 nanofibers with fiber-in-tube structures and featuring highly crystallized ultrafine nanorods (which have high electrical conductivity) showed superior rate performance compared to the (Co1/3Fe2/3)Se2-Se-C composite nanofibers with filled structures.
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)