Constructing heterostructured CoSe2-SnSe nanoparticles incorporated carbon nanofibers for robust sodium storage

Metal selenides receive significant attention as sodium-ion battery (SIB) materials by virtue of their high theoretical capacity and remarkable electrical conductivity. Nonetheless, the large volume change during cycling limits their large-scale employment on account of unsatisfied cyclic durability and rate performance. To tackle these problems, CoSe2-SnSe nanoparticles anchored on carbon nanofibers (CoSe2-SnSe@CNF) are initiated. The electrochemical property of CoSe2-SnSe@CNF in SIBs is found to be superior to those of CoSe2@CNF and SnSe@CNF, which is also illustrated by density functional theory (DFT) calculations. It is noteworthy that the CoSe2-SnSe heterostructures with built-in electric fields greatly stimulate charge transfer and Na+ transportation. Moreover, CNF, as the critical scaffold, immobilizes the CoSe2-SnSe nanoparticles, effectively suppressing the volume swelling and accelerating charge transportation. As expected, the CoSe2-SnSe@CNF exhibits a high capacity of 356.4 mAh g-1 after 100 cycles at 0.1 A g-1 and a reversible capacity of 248.7 mAhg-1 at 1 A g-1 underneath 1000 cycles..