Paradigm metallothermic-sulfidation-carbonization constructing ZIFs-derived TMSs@Graphene/CNx heterostructures for high-capacity and long-life energy storage

Enhancing electrochemical activity and structural stability of transition metal sulfides (TMSs) are critical for improving the capacity output and retention of TMSs-based batteries. Here, we report a new paradigmatic approach for fabricating TMSs/C composites, adopting a metallothermic-sulfidation-carbonization strategy (2TM + CS2 = 2TMS + C) based on zeolitic imidazolate frameworks (ZIFs) to synchronously construct a compact TMSs@Graphene/CNx triple heterostructure. The obtained structure features crystalline TMSs nanoparticles wrapped by few-layer graphene and totally embedded within porous carbonized polyhedral frameworks. All three nanocomponents of TMSs@Graphene/CNx are connected via chemical bonding of S-C and TM-C, forming a chemical cross-linked nanostructure. Such structure design bears intrinsic advantages in improving the volumetric-efficiency for accommodating TMSs and electrical properties, enabling promising electrochemical performance in lithium-and sodium-ion storage. As a representative, the ZnS@Graphene/CNx electrode exhibits a high capacity of 891.5 mAh g-1 and an excellent retention of 80 % after 1000 cycles in lithium-ion batteries. More notably, this general metallothermic-sulfidation-carbonization mechanism can be applicable to all ZIFs, defining a new ZIFs-derived TMSs/C heterostructures.