Ultrafast and Stress‐Adaptive Magnesium Conversion in Hollow NiS 2 @N‐Doped Carbon Cathodes via Interfacial Ni─N Bonding Modulation

ABSTRACT Conversion‐type nickel sulfide (NiS 2 ) is a compelling cathode for rechargeable magnesium batteries (RMBs) owing to high theoretical capacity, yet suffers from severe volume changes, polysulfide shuttling, metal dissolution, and sluggish kinetics caused by strong Ni─S bonds. To overcome these challenges, the interfacial optimization and bond regulation are of crucial importance. Herein, nitrogen‐doped carbon (NC)‐armored NiS 2 hollow microspheres (NiS 2 @NC) is designed with interfacial Ni─N bonding modulation. The introduced Ni─N bonds elongate and weaken adjacent Ni─S bonds, significantly lowering the conversion energy barrier and accelerating Mg 2 + storage kinetics. The synergistic effect of chemical anchoring (Ni─N bonds) and physical confinement (NC coating) suppress side reactions and shuttle effects, stabilizing the cathode‐electrolyte interface (CEI) and electrode structure. The unique hollow structure further promotes rapid Mg 2+ diffusion and accommodates the volume variation. Experimental and calculation results confirm that NiS 2 @NC material possesses excellent stress‐adaptive ability, mitigating volume fluctuations and preserving structural integrity. As a result, the NiS 2 @NC cathode delivers a high specific capacity (392 mAh g −1 at 0.2 A g −1 ), excellent long‐term cyclability (capacity retention of 92.8% after 3200 cycles at 5 A g −1 ), and superior rate capability. This interfacial bonding engineering strategy provides a universal pathway for designing high‑performance and robust conversion‑type electrodes in RMBs.