Potassium Ion-Intervened Copper-Nickel Bimetallic Organic Framework with Potassium Hydrogen Phthalate Ligand for High-Performance Aqueous Potassium Ion Hybrid Supercapacitors

To develop high-performance electrode materials for potassium-ion hybrid supercapacitors (PICs), a bimetallic metalorganic framework (MOF) CuNi-KHP (Potassium Hydrogen Phthalate) was prepared via a solvothermal method. The material features a 3D architecture constructed by stacking 2D nanosheets, with Cu/Ni bimetallic nodes and a multi-layered structure. Potassium ions were pre-inserted into the MOF using potassium hydrogen phthalate as the ligand, which regulates interlayer interactions and creates hierarchical pores for ion transport. Electrochemical characterizations show that CuNi-KHP exhibits a high specific capacitance of 1568.58 F/g at 0.5 A/g, accompanied by an energy density of 50.52 Wh/kg and a power density of 676.12 W/kg. It also maintains 90.1% capacity retention after 10,000 cycles. The assembled CuNi-KHP//AC hybrid PIC delivers an energy density of 76 Wh/kg and a power density of 812 W/kg at 0.5 A/g, with a Coulombic efficiency of 75% after 10,000 cycles at 1 A/g. These results demonstrate that CuNi-KHP is a promising cathode material for high-performance PICs, owing to its synergistic bimetallic effect and K+-regulated porous structure.