Gadolinium doped ZnS particles as electrode material for supercapacitor application

Supercapacitors (SC) have gained prominence among many advanced technologies because of their superior power density, fast charge/discharge capabilities, extended cycle lifespan, and remarkable operational stability. Recent advancements in ZnS nanostructures underscore their potential for high-performance SCs, especially when their morphology and surface characteristics are carefully engineered. Incorporating dopants into ZnS has proven effective in further enhancing its electrochemical performance. Adding dopants into the ZnS lattice results in defects, such as zinc and sulfur vacancies and interstitial atoms. In this study, ZnS doped with varying concentrations of Gd ions serves as an electrode material in supercapacitor devices. The influence of the induced defect states and Gd-ions concentration, characterized by photoluminescence, Raman, and electron paramagnetic resonance spectroscopy, on the electrochemical properties was demonstrated through cyclic voltammetry, potentiostatic electrochemical impedance spectroscopy, and galvanostatic cycling with potential limitation. The findings indicate that ZnS doped with a nominal concentration of 0.5% Gd has the highest specific capacitance value, achieving a maximum of 114.7 F/g at 2 mV/s, and demonstrates excellent cyclic stability, retaining about 98% of its capacity after 2000 cycles. It also showcases impressive performance in terms of energy and power density, with values reaching up to 15.93 Wh/kg and 1146 W/kg, respectively. These findings underscore the potential of Gd-doped ZnS as high-efficiency electrodes in supercapacitors, playing a crucial role in advancing sustainable and efficient energy storage solutions that effectively balance energy and power density.