Zeolitic imidazolate framework-67 derivative/graphene composite for defect-enhanced epitaxial growth and improved Li+ storage in lithium-ion batteries

Defect-assisted epitaxial growth of metal–organic frameworks (MOFs) on conductive substrates offers an efficient strategy for enhancing electrochemical performance. In this study, a rational approach is proposed to promote the epitaxial growth of ZIF-67 on graphene by precisely tuning the Co 2+ to 2-methylimidazole molar ratio, thereby improving lithium-ion storage capabilities. The resulting NiCo 2 O 4 @ZIF-67/graphene (NCO/Z67G-2) composite exhibits outstanding electrochemical performance, delivering a high reversible capacity of 1298.5 mAh g −1 after 100 cycles and a rate capability of 601.1 mAh g −1 at 1.4 A g −1 . Structural characterization indicates that optimized metal–ligand coordination facilitates defect-assisted epitaxial growth of ZIF-67 along the (001) crystal plane, resulting in a highly conductive interface enriched with Co-N-C active sites. Electrochemical analyses further reveal that the superior performance stems from a capacitive-dominated lithium storage mechanism, fast ion diffusion kinetics, and the formation of a thin and uniform LiF-rich solid electrolyte interphase (SEI), which collectively contribute to the reduced charge transfer resistance (88.01 Ω). This study provides valuable insights for the rational design of advanced electrode materials via interface engineering and defect regulation in high-performance energy storage systems.