Exploring the potential energy storage capability of NiCdS2 nanocomposites: insights through promising electrochemical, impedance and dielectric analysis

Ternary metal sulphide nanocomposites are gaining prominence for their energy storage properties and applications. In this work, ternary NiCdS2 (NCS) nanocomposites were prepared via standard solvothermal method. Rietveld examination of the PXRD was revealed cubic NiS2 and hexagonal CdS phases in NCS nanocomposites. The electron density, average crystallite size, crystalline parameters, micro-strain and dislocation density were determined. EDX analysis confirmed the elemental composition, while XPS was used to investigate the chemical states and bonding environments of Ni, Cd and S. Ellipsoid morphology with particle size in the ranging of 20–60 nm was investigated using HRTEM. Electrochemical behaviours were investigated through cyclic voltammetry and galvanostatic charging/discharging, which shows quasi-rectangular shape curve with higher specific capacitance and fast-charging and slow-discharging rate. Complex impedance/modulus spectra, dielectric properties and electrical conductivity were investigated at temperatures ranging from 308 to 423°K at various frequencies. Nyquist plots demonstrate two RC-equivalent circuits owing to the contribution of grains and grain boundaries, which investigates the non-Debye-type dielectric relaxation in NCS. The dielectric constant increased with temperature and found to be more than 10000 (huge) at higher temperature/low frequencies and the dielectric loss was exhibited an increasing trend with temperature. The correlated barrier hopping (CBH) model was adopted to explain the mechanism of conduction through Jonscher’s power law. The hopping parameters, like binding energy, activation energy, minimum hopping distance and density of states at fermi level, were evaluated at various temperatures. Furthermore, the non-Debye-type nature of the relaxation in the NCS has been established by using the Kohlrausch–Williams–Watts (KWW) model to complex modulus spectra. NCS nanocomposites were identified as potential alternates for energy storage devices because to their higher dielectric constant values and superior electrochemical performance.