High-performance MOF electrode for supercapacitors with enhanced quantum capacitance through optimal multi-metal integration

Abstract

As the demand for high-performance energy storage surges, supercapacitors (SCs) have become vital due to their high-power density, rapid charge/discharge cycles, and long lifespans. In this study, we present an innovative in-situ synthesis method for multi-metallic MOF-74 with optimized Mn/Co ratios directly grown on nickel foam (NF). This substrate acts not only as an electrode but also contributes nickel ions during synthesis, forming a synergistic MnCoNiMOF-74 composite. Electrochemical tests in a three-electrode system show that the 3:1 Mn/Co electrode achieves an impressive areal capacity of 4390 mF cm−2 at 2 mA cm−2. The microporous structure, enriched with various metals, minimizes ion transport resistance, enhancing electrochemical activity. First-principles density functional theory (DFT) simulations indicate that the 3:1 Mn/Co ratio yields the highest quantum capacitance of 4752 μF cm−2, demonstrating strong electronic interactions among metal centers, which improve electron density around the fermi level. Notably, the MnCoNiMOF-74/NF electrode exhibits excellent cycle stability, maintaining performance even after 10,000 charge-discharge cycles at 10 mA cm−2. The MnCoNiMOF-74/NF (3:1)//AC asymmetric supercapacitor (ASC) device exhibits a high energy density of 75.8 Wh kg−1 at 533 W kg−1, with stable charge storage (640 mF cm−2 at 2 mA cm−2) and well-matched redox kinetics, ensuring reliable performance for energy storage applications. The proposed electrode demonstrates exceptional stability, high capacity, and quantum insights, offering a scalable and efficient solution for energy storage technologies. These attributes make it highly promising for the future of advanced SCs and their practical applications in energy systems.