Double‐Carbon‐Layer Core–Shell Complex Sulfides Derived from Bimetallic Metal–Organic Frameworks for Li‐/Na‐Ion Battery Storage

Metal–organic frameworks (MOFs) have been extensively studied due to their porous structures and large specific surface areas. Its unique combination of central metal and organic ligand has become a common precursor for the synthesis of metal phosphides, selenides, oxides, and sulfides. However, the carbonaceous structure derived from some MOF materials is still not enough to perfectly alleviate the negative impact of the volume change of metal sulfides. Herein, bimetallic MOF (Zn‐Co‐ZIF) is used as a precursor, coated with dopamine hydrochloride, and then calcined and gas‐phase vulcanized to prepare ZnS/CoS₂‐C@NC with a double‐carbon‐layer core–shell structure. The existence of the two carbonaceous structures can not only improve the electron transport ability, but also play an important role in alleviating the volume expansion caused by metal sulfides during repeated charging and discharging. Due to its stable carbon layer structure, ZnS/CoS₂‐C@NC has a higher specific capacity (1175.4 mAh g⁻¹ in lithium‐ion batteries (LIBs) and 430.9 mAh g⁻¹ in sodium‐ion batteries after 100 cycles at a current density of 0.2 A g⁻¹ respectively) and excellent rate capability (338.2 mAh g⁻¹ specific capacity maintained after 2000 cycles at a current density of 5 A g⁻¹ in LIBs).