Browsing by Author "Ashish Raj"

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Humidity Effect on Ionic Conductivity of Composite Polymer Electrolytes
(John Wiley and Sons Inc, 2023) Ashish Raj; Kushal Mehrotra; S.P. Pandey; S. Venkatesan Jayakumar; Amit Saxena; Bhaskar Bhattacahrya
The solid polymer electrolytes (SPE) based electrochemical devices are an area of attention for more than two decades. The ability of thin-film preparation and leakage proof over the liquid counterpart are the key factors of SPE. In the present work, two different compositions, 80–20 and 85–15, of PVA:KI has been used as a host polymer complex. Where further 10 wt% of p-Si dispersed with PVA:KI complexes. Polymer films have been prepared with standard solution cast techniques, which are further characterized for their electrical conductivity by Electrical Impedance Spectroscopy (EIS). Also, the humidity effect on the ionic conductivity of these thin films is calculated. It is observed that the ionic conductivity of these polymer electrolytes films increases with 58%, 74%, and 89% humidity. To understand the change in this ionic conductivity, the concentration and mobility of ions are also calculated, and it is found that the change in conductivity are predominately influenced due to the mobility of charge carriers. © 2023 Wiley-VCH GmbH.
Humidity-Dependent Ion Conduction Mechanism of PVA-Based Polymer Electrolyte Films
(John Wiley and Sons Inc, 2023) Kailash Kumar; Kushal Mehrotra; Ashish Raj; Shri Prakash Pandey; Bhaskar Bhattacharya
Polymer electrolytes are studied worldwide for their possible applications in various electrochemical devices. In the last few decades, a large number of polymer electrolytes have been developed and characterized. However, in most cases, the effect of humidity has been ignored. In this paper, we report a systematic study on a polymer electrolyte's electrical and dielectric properties at different humidity. The chosen system is a Polyvinyl Alcohol (PVA) based polymer electrolyte in which potassium iodide (KI) with differing weight percentage is selected as the dopant salt for the synthesis of PVA-KI films. Four different compositions of PVA-KI films are synthesized using the solution cast technique. Electrical impedance spectroscopy (EIS) technique is used to determine its conductivity at three different humidity levels: 55%, 75%, and 85%. Analysis of dielectric permittivity and electrical modulus of the films is also done at these humidity levels. The highest conductivity for all the four different compositions of films is found to be at 85% humidity level, of which the optimum ionic conductivity is seen in the 75:25 composition of PVA:KI with a value of 1.25×10−4 S cm−1.The number of charge carriers and their mobility are calculated for all samples at different humidity levels. A correlation has been established between the conductivity of the films and the mobility of charge carriers. © 2023 Wiley-VCH GmbH.
(ICSEM 2025): Electrical Properties of Nano-ZnS Incorporated Polymer Electrolyte Films: A Conductivity Analysis for Energy Devices
(John Wiley and Sons Inc, 2025) Ashish Raj; Pavan Kumar Singh; Munendra Singh; Amit Saxena; Bhaskar Bhattacharya; Shri Prakash Pandey
The tunable electrical conductivity of nano-ZnS-doped polymer electrolyte films presents substantial possibilities for a variety of devices. The main goal of this study is to find the best way to make polymer electrolyte films work better in electrochemical devices by looking into how their electrical properties change with concentration. We selected poly(vinyl alcohol) (PVA) and potassium iodide (KI) as the polymer electrolyte matrix based on their composition, which exhibited maximum conductivity. Nano-ZnS was synthesized via the chemical precipitation method and incorporated as a nanofiller into the PVA-KI matrix at varying concentrations using a controlled stirring process. Solution casting approach was adopted to fabricate the polymer electrolyte films. We studied the electrical properties of the free-standing solid polymer composite films using impedance spectroscopy, the structural properties using X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the optical properties using Fourier-transform infrared spectroscopy (FTIR). The results indicate that the ionic conductivity of the films increases with increasing nano-ZnS concentration up to a critical threshold, beyond which conductivity plateaus or declines. The maximum conductivity of 4.1 × 10−⁴ S/cm was obtained for 7 wt.% concentration. We further analyze this conductivity behavior in relation to the dispersion of nano-ZnS within the polymeric matrix and its influence on ionic transport mechanisms. These findings offer insights into the optimal nano-ZnS concentration required to achieve high conductivity in polymer composite electrolytes, contributing to the development of efficient and durable solid-state batteries and electrochemical sensors. © 2025 Wiley-VCH GmbH.