Design of high-mass loading metal–organic framework-based electrode materials with excellent redox activity for long-lasting electrochemical energy storage applications

Nowadays, metal–organic framework-derived (MOF-D) materials are auspicious in various research areas due to their beneficial traits of diverse structural features, large surface area, and high porous nature. Herein, we report the MOF-D nickel–cobalt terephthalate hydroxides (Ni-Co THs) via a one-pot solvothermal approach without further annealing. Direct growth of active materials on conductive substrates (e.g., nickel foam (NF)) can potentially eliminate the use of sluggish and non-conductive binders, leading to enhanced redox chemistry with commercial-level mass loading (8–10 mg cm⁻²). All the binder-free MOF-D Ni-Co TH electrodes demonstrated excellent areal capacities at the same current density of 3 mA cm⁻². Among them, the Ni-Co TH-160/9h electrode delivered a superior areal capacity/specific capacity of 2087 µAh cm⁻²/200.68 mAh g⁻¹ at 3 mA cm⁻², together with outstanding cycling retention of 100 % after 20,000 charge–discharge cycles. The achieved ultrahigh performance is ascribed to the synergistic properties of Ni-Co THs, three-dimensional porous NF, and morphological structures. Utilizing the charge storage performance of the Ni-Co TH-160/9h electrode, an electrochemical cell (ECC) was assembled. The as-assembled ECC delivered good areal capacity (1678.6 µAh cm⁻²), energy density (1.3 mWh cm⁻²), and power density (48.6 mW cm⁻²) with outstanding cycling performance (35,000 cycles (99.9 %)). Also, the ECC verified its energy storage properties by powering various portable electronic appliances.