CoS/V3S4 heterostructures wrapped by nitrogen-sulfur co-doped carbon for ultra-fast-charging sodium-ion batteries

Metal sulfides are attractive anodes for sodium-ion batteries due to their high capacity and low polarization. However, single metal sulfides suffer from severe volume changes and sluggish kinetics. Constructing heterostructures offers a promising strategy, yet rational designs that achieve genuine ultra-fast charging capability remain scarce. Herein, we report metallic disc-like CoS/V 3 S 4 heterostructures encapsulated in nitrogen‑sulfur co-doped carbon (CoS/V 3 S 4 @NSC). When evaluated with an ether-based electrolyte, the optimized CoS/V 3 S 4 @NSC exhibits high initial Coulombic efficiency (>90%), high reversible capacity (622.6 mAh g −1 at 0.5 A g −1 ), excellent stability (291.5 mAh g −1 after 300 cycles at 15 A g −1 ), and remarkable ultra-fast charging capability (143.1 mAh g −1 at 40 A g −1 within 12 s). Combined in situ/ex situ studies and density functional theory calculations reveal metallicity, enhanced Na + diffusion, and a pseudocapacitive-dominated conversion mechanism. Full cells assembled with Na 3 V 2 (PO 4 ) 3 @rGO cathodes further demonstrate long-term stability (414.1 mAh g −1 after 1500 cycles at 1 A g −1 ) and outstanding rate capability (324.8 mAh g −1 at 5 A g −1 ). This work highlights a rational heterostructure design that enables practical ultra-fast sodium-ion storage. N,S co-doped carbon encapsulated disc-like CoS/V 3 S 4 heterostructures manifest remarkable ultra-fast charging ability as advanced sodium-ion battery anodes. Various in situ/ex situ studies and DFT calculations confirm metallicity, boosted Na + diffusion, and pseudocapacitive dominated conversion mechanism. The assembled high-performance full cells demonstrate the possibility of rational heterostructure design for practical ultra-fast sodium-ion storage. Download: Download high-res image (221KB) Download: Download full-size image