Attaining high energy density using metal-organic framework-derived NiO/ Co₃O₄/NiCo₂O₄ as an electrode in asymmetric hybrid supercapacitor

This study investigates the potential of hybrid NiO/NiCo2O4/Co3O4 composite as electrode for high-performance supercapacitors. Hydrothermally synthesized Ni(BDC) and Co(BDC) as sacrificial templates with different mass ratios are used to obtain NiO/NiCo2O4/Co3O4 nanocomposite. Notably, the electrochemical studies revealed that NiO/NiCo2O4/Co3O4 derived from a 4:1 mass ratio of Ni-MOF and Co-MOF displayed the highest specific capacity value of 1108.9C g-1 at 2 A g-1 with enhanced rate capability and excellent electrochemical stability, with 95.3 % retention up to 5000 cycles at 10 A g-1. The enhancement of specific capacity is attributed to the multiple metal oxidation states (Ni2+, Ni3+, Co2+, Co3+), surface oxygen defects, and the reduced solvation effect due to mesoporous structure and higher specific surface area. The assembled hybrid asymmetric supercapacitor (NiO/ NiCo2O4/Co3O4 //Carbon Black) demonstrated a remarkable specific capacity of 416.95C g-1 at 0.5 Ag-1 with 89.1 % retention up to 5000 cycles at 10 A g-1 and an exceedingly high energy density of 89.81 W h kg- 1 at a power density of 387.49 W kg- 1. Even at a high-power density value of 7740 W kg- 1, the device maintained an impressive energy density of 72.43 W h kg- 1.