Assembly of\nMetal–Organic Frameworks on Transition\nMetal Phosphides as Self-Supported Electrodes for High-Performance\nHybrid Supercapacitors

Abstract

In this work, the composite electrode\ncomposed of metal–organic\nframeworks and transition metal phosphides is first assembled on the\nnickel foam substrate. The as-prepared NiCo-MOF-74@Ni₁₂P₅/NF exhibits excellent performances with ultrahigh specific\ncapacitance (12.8 F/cm² at 1 mA/cm²), stable\ncharge–discharge rate (82.8%), and excellent cycling stability\n(reserve 73.90% after 5000 charge and discharge cycles at 30 mA/cm²), which are better than those of NiCo-MOF-74@NF without phosphating\ntreatment of nickel foam. The corresponding hybrid supercapacitor\n(SC) device (NiCo-MOF-74@Ni₁₂P₅/NF//AC) delivers\nhigh storage capability (44.33 W·h/kg at 800 W/kg) and distinguished\noperating durability (83.04% after 5000 cycles). In addition, an all-solid-state\nhybrid SC successfully lit the LED for more than 2 min, which means\nthat there is viable potential for practical applications in energy\nstorage. The improved electrical properties are mainly due to the\n3D heterostructure, the positive cooperative binding of nickel and\ncobalt elements, and the excellent electrical conductivity of the\nphosphide. As a result, this study proves the possibility of practical\napplications of NiCo-MOF-74@Ni₁₂P₅/NF electrodes\nfor energy storage in hybrid SCs.