Design and electrochemical performance of Ni-MOF/rGO heterostructures for high-capacity supercapatteries

Abstract

The growing demand for energy storage systems that combine high power density with long cycle life intensifies the search for advanced electrode materials. In this work, a composite material comprising a two-dimensional nickel metal–organic framework (Ni-MOF), derived from 2-methylimidazole, and reduced graphene oxide (rGO) is synthesized to address this challenge. The structural compatibility between the sheet-like 2D Ni-MOF and layered rGO enables the formation of an interconnected 2D/2D heterostructure that integrates the high surface area and redox activity of the MOF with the excellent electrical conductivity and mechanical flexibility of rGO. This intimate interface facilitates rapid ion diffusion and efficient electron transport, resulting in enhanced electrochemical properties. The Ni-MOF/rGO composite functions as an electrode material for supercapattery applications and is evaluated using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). The Ni-MOF/rGO electrode delivers a high specific capacity of 349.83 C g⁻¹ at a current density of 1 A g⁻¹, significantly outperforming the individual components. A symmetrical device (Ni-MOF/rGO‖Ni-MOF/rGO) also exhibits excellent cycling stability, retaining 87.3% of its capacity over 10 000 charge–discharge cycles. These results highlight the potential of structurally engineered Ni-MOF/rGO composites as advanced electrode materials for next-generation hybrid energy storage devices.