Significantly enhanced ion‐migration and sodium‐storage capability derived by strongly coupled dual interfacial engineering in heterogeneous bimetallic sulfides with densified carbon matrix

Abstract The development of highly efficient sodium‐ion batteries depends critically on the successful exploitation of advanced anode hosts that is capable of overcoming sluggish reaction kinetics while also withstanding severe structural deformation triggered by the large radius of Na + ‐insertion. Herein, a hierarchically hybrid material with hetero‐Co 3 S 4 /NiS hollow nanosphere packaged into a densified N‐doped carbon matrix (Co 3 S 4 /NiS@N‐C) was designed and fabricated utilizing CoNi‐glycerate as the self‐sacrifice template, making the utmost of the synergistic effect of hetero‐Co 3 S 4 /NiS with strong electric field and rich reaction active‐sites together with the densified outer‐carbon scaffolds with remarkable electronic conductivity and robust mechanical toughness. As anticipated, as‐fabricated Co 3 S 4 /NiS@N‐C anode affords remarkable specific capacity, prolonged cycle lifespan up to 2 400 cycles with an only 0.05% fading each cycle at 20.0 A g −1 , and excellent rate feature (354.9 mAh g −1 at 30.0 A g −1 ), one of the best performances for most existing Co 3 S 4 /NiS‐based anodes. Ex situ structural characterizations in tandem with theoretical analysis demonstrate the reversible insertion‐conversion mechanism of initially proceeding with Na + de‐/intercalation and superior heterogeneous interfacial reaction behavior with strong Na + ‐adsorption ability. Further, sodium‐ion full cell and hybrid capacitor based on Co 3 S 4 /NiS@N‐C anode exhibit impressive electrochemical characteristics on cycling performance and rate capability, showcasing its outstanding feasibility toward practical use.