Phytogenic generation of NiO nanoparticles as green-electrode material for high performance asymmetric supercapacitor applications

Abstract

Herein, we report a simple, cost-effective, one-step green synthesis of nickel oxide nanoparticles (NiONPs) from Opuntia ficus-indica leaves extract for asymmetric supercapacitor application. The plant extract derived NiONPs exhibits an exceptional half-cell specific capacitance of 644 Fg−1 (~89.4 mAhg−1) at 0.5 Ag−1. The assembled asymmetric NiONPs|| activated carbon (AC) supercapacitor cell delivers high specific capacitance of ~280 Fg−1 (~38.8 mAhg−1), excellent specific energy of 25 Wh kg−1. In addition, the NiONPs|AC device works until 1.4 V with 0.1 M KOH as electrolyte delivering an excellent rate capability and high coulombic efficiency of 124% even after 10,000 cycles. Moreover, the biomass derived NiO NPs performs better than the other reported NiO based compounds, due to its presence of nickel-rich natural minerals. Through these findings, the use of plant leaves like Opuntia ficus-indica is hereby shown to be low-cost, environment-friendly alternative for preparing NiO- based composites for energy storage applications.