Development of NiS and Biomass-Derived Carbon Spheres Composite for High-Performance Supercapacitor Electrodes

The development of innovative and efficient energy storage technologies has become a critical concern in modern society due to the ongoing depletion of conventional power reserves and increasing environmental pollution. To address the rising current and future energy demands, it is imperative to implement a “Green” strategy that leverages the numerous accessible energy sources, minimizing environmental impact while deriving value from waste. Consequently, this study reports the synthesis of a nickel sulfide and onion peel-derived carbon sphere composite (NiS/OPCS) through an economical hydrothermal process. The synthesized composite has been optimized using various characterization techniques. Electrochemical performance was optimized through cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) analyses. The NiS/OPCS composite demonstrated exceptional retention of 95.66% after 6000 cycles, with a significant specific capacitance value of 707 F/g at 1 A/g current density. Both capacitive-controlled and diffusion-controlled mechanisms were found to contribute significantly to charge storage. Therefore, NiS/OPCS is a promising candidate as an electrode material for supercapacitor applications.