Effect of salts on the fumed silica-based composite polymer electrolytes

Polymer electrolytes, which are ubiquitous and indispensable in all electrochemical devices, have been investigated and a study to explore their performance characteristics on salt type and salt concentration and different binary solvents has been performed. LiBETI salt exhibits less variation with change in molar concentration and is expected to form less ion pair formation. It has been realized that though the addition of inert ceramic fillers, i.e. fumed silica, enhances the mechanical integrity but decreases conductivity marginally in the Lilm, LiBETI and LiBF4 based salt. This decrease in conductivity is due to their more interaction with the PMMA as established by FTIR. Moreover these electrolytes were found to be exhibited high conductivity (> mS/cm) to warrant their practical applications. The glass transition temperature increases with the addition of fillers pointing towards the lower mobility of Li+ ions and these electrolytes also exhibit high-thermal stability. (c) 2007 Elsevier B.V. All rights reserved.