Insight into the effect of active facets engineered heterostructure in boosting sodium-ion storage: The case study of FeS2/CoS2

The poor kinetic property and inferior cyclic stability of Sodium ion batteries (SIBs) anode limits the practical application. Herein, a typical FeS 2 /CoS 2 heterostructures engineered with different active facets was synthesized by solvothermal method followed by cation exchange process. Structural characterizations confirm successful formation of the target materials. Electrochemical tests reveal that heterostructure composed of FeS 2 {1 1 1} active facets and CoS 2 (FeS 2 /CoS 2 -H) maintained superior sodium storage performances than heterostructure composed of FeS 2 {1 0 0} facets and CoS 2 (FeS 2 /CoS 2 -L). Specifically, FeS 2 /CoS 2 -H electrode delivered 539.4 mAh g −1 after 100 cycles at 0.1 A g −1 and superior rate capability (264.5 mAh g −1 at 5.0 A g −1 ). Kinetics analysis indicates that FeS 2 /CoS 2 -H possesses higher pseudocapacitive contribution ratio and sodium diffusion coefficient. Density functional theory (DFT) calculations further verify that highly active facet fabricated heterostructure manifests superior Na + adsorption energy and decreased diffusion energy barrier. This work highlights that engineering heterostructures with highly active facets is an effective strategy for developing high-performance anode for SIBs.