As a result of the high theoretical capacities, transition
metal
sulfides have attracted increasing attention as potential anodes for
sodium-ion batteries (SIBs), but severely suffer from large volumetric
variations, sluggish kinetics, and polysulfide shuttling. Herein,
utilizing metal–organic frameworks (MOFs) as functional templates,
heterostructured CoS2/FeS nanoparticles confined in a hollow
N-doped carbon framework are successfully fabricated via a controlled ion-exchange reaction combined with subsequent carbonization
and sulfurization processes. The construction of CoS2/FeS
heterointerfaces promotes electron transfer and provides more active
sites, while the derived N-doped carbon framework with a unique hollow
interior effectively improves the electrical conductivity, alleviates
the volumetric variations, and facilitates the sodium storage process
with shortened Na+ diffusion paths. As anodes for SIBs,
the optimal CoS2/FeS hybrid composite exhibits a high initial
Coulombic efficiency (ICE) of 89.3%, a prolonged cycle life with a
capacity of 494 mAh g–1 over 500 cycles under a
current density of 1.0 A g–1, and an excellent rate
capability of 428 mAh g–1 at 5.0 A g–1, showing the great promise for SIBs. This research offers an efficient
and feasible approach for exploring and fabricating bimetallic sulfide
heterostructures with a unique hollow structure for high-performance
metal-ion batteries.