JMS_V3_N2_RP3 Rajiv Kumar Journal on Material Science 2347–615X 3 2 21 27 Nanocomposite, Conductivity, Dimethylacetamide, Dielectric Constant, Fumed Silica Nanocomposite Polymer Gels (NCPG) composed of Polymethylmethacrylate (PMMA), Lithium Perchlorate (LiClO4), Dimethylacetamide (DMA), Dimethyl carbonate (DMC) and Nano sized fumed silica (SiO2) were prepared to improve the ionic conductivity and mechanical stability of solid state electrolytes. The increase in conductivity with the polymer addition has been explained to be due to the dissociation of undissociated salt present in the electrolytes. With the addition of nano-sized fumed silica (SiO2 ) to the gels, the ionic conductivity further increased which has been explained on the basis of double percolation threshold model. The dependence of conductivity of NCPGs on temperature was also measured, and a maximum room temperature conductivity of 2.45×10-2 S cm-1 was obtained for electrolytes composed of DMA+0.5M LiClO4 + 10 wt% PMMA + 8 wt% SiO2 . The effect of dielectric constant of solvent has also been studied. The conductivity of composite gels does not show much change over 20-1000 C temperature range and also remains constant with time which is suitable for their use as electrolytes in various devices like solid state lithium ion batteries, electrochemical display devices, electrochemical sensors, etc. July – September 2015 Copyright © 2015 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=3503