Synergistic Tuning of Electrochemical Performance in Ni-Modified CuCo-MOFs for Flexible Energy Storage Devices

Abstract The rapid expansion of flexible, portable, and wearable electronic technologies has heightened the need for energy-storage systems that provide mechanical durability and operational safety. MOFs (Metal Organic Frameworks) have attracted considerable attention due to their highly tunable porous architectures, large accessible surface areas, and abundant redox-active metal centers. In this work, a Ni intercalated bimetallic CuCo-BDC MOF was synthesized, aiming to exploit multimetal synergistic effects, enhance redox activity, and improve ion-transport dynamics. Structural and morphological analyses confirm that Ni incorporation preserves the crystalline integrity and mesoporous, sheet-like architecture of the parent framework. Electrochemical investigations demonstrate that the Ni-CuCo-BDC MOF significantly enhanced charge storage behavior, achieving a high areal capacity of 82.917 μAh cm–2 at a current density of 1 mA cm–2 in a three-electrode configuration. The assembled solid-state FES device exhibits a capacity of 13.389 μAh cm–2, an energy density of 5.356 μWh cm–2, and a power density of 400 μW cm–2, along with excellent mechanical flexibility and ∼90.2% capacity retention after 5000 cycles. These outcomes highlight the potential of the Ni-CuCo-BDC MOF as a promising energy storage candidate for wearable and portable electronics.