Miniaturization of binary metal sulfides electrode materials in water-ethanol solvent medium: Remarkable improvement in specific capacitance and cyclic stability

Abstract

Binary metal sulfides have synthesized at ambient temperature as a positive electrode using ethanol-water as a solvent in the co-precipitation process. The incorporation of sulfur (S) into transition metals could have controlled by changing the solvents, including ethanol and water. The average particle size was measured around 15 nm using electron microscope. The specific surface area calculated around 145 m2 g-1 through NMR based relaxation method. Moreover, it has been found that the particular composition of CNS 1:1:0.15 has drawn immense electrochemical properties based on their discrete morphology. The binary sulfide electrode exhibits excellent pseudocapacitance performance, and delivered specific capacitance (SC) of 2910 F g-1 at 1 A g-1, and simultaneously depicted adequate cyclic retention ~91.5 % up to 10,000 cycles. The energy density (ED), and power density (PD) were evaluated for active electrode about ~123 Whkg−1 and ~285 W kg-1 respectively. Meanwhile, the influence of cation species (Na+, K+& Li+) in electrolyte concentrations illustrates the outstanding supercapacitive performance by decreasing internal resistance. An asymmetric solid-state (ASC) supercapacitor device was assembled which brighten the ~1.8 V of commercial LED for the validation of electrode.