Efficient Synthesis of MOF-Derived Ni₂CuO₃/CuO Nanocomposites Cathode and Fe₂O₃/N-rGO Composite Anode for a High-Performance All-Solid-State Asymmetric Supercapacitor

Recently, metal–organic framework (MOF)-derived binary transition-metal oxide (BTMO) holds promise as an ideal electrode material for energy-storage applications. Here, we report a facile synthesis procedure of MOF-derived BTMO that commences with the preparation of Cu-MOF through the coordination of Cu2+ with 2-MeIM. Subsequently, Ni2+ is introduced into the Cu-MOF to create Cu2+ and Ni2+ binary clusters, resulting in the formation of Ni-Cu-MOF. Finally, annealing of Ni-Cu-MOF led to the formation of a nanoflakes morphology of Ni2CuO3/CuO (denoted as NCO/CuO) composite that serves as an efficient pathway for both ion and electron transportation, creating plentiful active sites for the faradaic charge storage process. Impressively, the NCO/CuO composite demonstrates significantly higher specific capacity (Cs) of 613.54 C/g compared to Ni-Cu-MOF (301.11 C/g) at a current density of 1 A/g and retains 66.3% of its initial capacitance at 15 A/g. Similarly, the Fe2O3-doped nitrogen-doped reduced graphene oxide (denoted as Fe2O3/N-rGO) composite prepared through a facile hydrothermal method demonstrates a specific capacitance (Csp) of 603.39 F/g at 1 A/g, surpassing its counterparts, Fe2O3, and N-rGO and retains 39.6% of its initial capacitance even at a higher current density of 15 A/g. Finally, a flexible asymmetric supercapacitor (ASC) device was designed and assembled using the Ni2CuO3/CuO composite as the positive electrode, Fe2O3/N-rGO as the negative electrode, and PVA-KOH gel as the electrolyte. The Ni2CuO3/CuO//Fe2O3/N-rGO ASC device demonstrates an excellent energy density of 48.26 Wh/kg at 1 A/g and a maximum power density of 11 250 W/kg and retains 86% of its capacitance after 10 000 cycles at 1 A/g. These findings provide valuable insights for high-performance energy-storage ASC devices for next-generation portable electronics.