Synthesis of dandelion-like bimetallic nickel‑cobalt metal-organic framework as an efficient cathode for high-performance asymmetric supercapacitors

This study employed pyromellitic acid (PMA) to synthesize a NiCo metal-organic framework (MOF) for supercapacitors. The resultant, NiCo-MOF (PMA), revealed a dandelion-like structure with a surface area reaching 500.7 m² g⁻¹. At the current density of 1 A g⁻¹, the NiCo-MOF (PMA) produced an impressive specific capacitance value of 918.8 F g⁻¹. It retained 61.1 % of the capacitance obtained at 1 A g⁻¹ even after increasing the current density to 10 A g⁻¹. Moreover, the 64.3 % capacitance retention was achieved even after 10,000 cycles of charging/discharging at 10 A g⁻¹. More importantly, the asymmetric supercapacitor (ASC) based on the NiCo-MOF (PMA) cathode demonstrated a specific capacitance of 83.47 F g⁻¹ at 0.5 A g⁻¹, and 80.34 % of its initial capacitance was still maintained after 5000 cycles at 5 A g⁻¹. The ASC delivered an energy density of 23.88 Wh kg⁻¹ at a power density of 750 W kg⁻¹. Two ASCs in a series successfully powered 120 green LED lights for 21 min, illustrating its potential practical applications.