Spatial confinement of Co1.67Te2 nanoparticles within porous carbon nanofibers enabling fast kinetics and stability for sodium dual-ion batteries

Owing to favorable cell voltage exceeding 3 V and cost-effectiveness, sodium dual-ion batteries (Na-DIBs) have gained increasing emphasis, however, they are hampered by the availability of suitable anode. Here, an exotic Na-DIB anode, composed of Co1.67Te2 nanoparticles embedded within porous carbon nanofibers (Co1.67Te2@PCFs), has been developed by a combination of electrostatic spinning and a specialized thermal etching process. The Co1.67Te2 nanoparticles within the confined space and porous carbon layers show energetic capability for Na+ storage and enhanced kinetic behavior of the cell, further verified by the density functional theory (DFT) calculations. Additionally, the formed thin, uniform, and inorganic-rich solid electrolyte interphase (SEI) on the surface of Co1.67Te2@PCFs after cycling reduces electrolyte consumption and facilitates the uniform flow of Na+. Electrochemically, the Co1.67Te2@PCFs anode exhibits a superior reversible capacity of 383.5 mAh g-1 and maintains stable cycling performance over 1000 cycles at 1 A g-1. Furthermore, the assembled Na-DIB can power a "SUST" pattern comprising 242 light-emitting diodes (LEDs) for two minutes, showcasing its operational potential. This study introduces a promising anode material for Na-DIBs and paves the way for spatially confined energy storage.