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

Abstract

In this current work, pyromellitic acid (PMA) was employed to synthesize a NiCo metal-organic framework (MOF) for supercapacitors. The resultant NiCo-MOF (PMA) showed dandelion-like structure and therefore its surface area was reached as high as 500.7 m2 g− 1. The NiCo-MOF (PMA) delivered an impressive specific capacitance value of 918.8 F g− 1 at the current density of 1 A g− 1. Upon increasing the current density to 10 A g− 1, it retained 61.1% of the capacitance obtained at 1 A g− 1. Moreover, the capacitance retention of 64.3% was achieved even after being charged/discharged at 10 A g− 1 for 10,000 cycles. More importantly, the asymmetric supercapacitor (ASC) based on the NiCo-MOF (PMA) cathode showed 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 5,000 cycles at 5 A g− 1. Furthermore, the ASC delivered an energy density of 23.88 Wh kg− 1 at a power density of 750 Wkg− 1. Additionally, two ASCs in series successfully drove 120 green LEDs lighting for 21 minutes, demonstrating its potential practical applications.