ZIF-67 Clusters with Small-Size Particles Confined by a Graphene Framework as a Promising Lithium-Ion Battery Anode

Composites based on metal-organic frameworks (MOFs), which feature a distinctive porous structure, are regarded as one of the leading candidates for anodes in the future of lithium-ion batteries (LIBs). However, their poor conductivity and structural pulverization effect hinder their widespread application in LIBs. In this study, we reported a new strategy that confines nanoporous ZIF-67 clusters within flexible graphene frameworks (ZIF-67@rGO) through solvothermal and annealing processes. The confinement within a small-size structure helps to relieve the volume pulverization effect and maintain the structural stability of the composites. Additionally, the graphene framework facilitates shorter pathways for rapid charge transmission and significantly boosts the conductivity of the electrode. Therefore, the resulting flexible 3D ZIF-67@rGO composite was directly pressed as a binder-free LIB anode, delivering an ultrahigh capacity of 1429 mAh g^-1 after 150 cycles at 0.1 A g^-1 and a superlong cycle performance of 1002 mAh g^-1 after 2500 cycles at 2 A g^-1. By combining experimental studies and GITT analysis, the kinetic behavior of lithium storage for the ZIF-67@rGO composite as an anode for LIBs was described. This work may open a new avenue for research on other MOF-based composites as electrodes for energy storage and conversion.