Synthesis and Ion Conductivity Studies of Na Ion Conducting Nano Composite Polymer Electrolytes

The ion conducting superionic solids or solid state ionic materials are new class of solid systems which exhibit high ionic conductivity comparable to liquid/ aqueous electrolytes. These materials, widely known as ‘Superionic Solids’ or ‘Solid Electrolytes’, show great technological promises as potential electrolyte systems to fabricate all solid-state electrochemical devices viz. batteries, fuel cells, super-capacitors, memories electrochromic displays etc. [1-6]. Among the known superionic solids, ion conducting polymer electrolytes (PEs) is one of the important areas of research in the last 30 years. Ion conducting PEs shows great technological promises to develop all-solid state devices viz. sensors, fuel cells and flexible thin film batteries in desirable shapes/ sizes [7-11]. The conventional solid polymer electrolyte films are found to be poor conductivity, less flexibility and less mechanical stability. Very recently, the nano-composite polymer electrolytes (NCPEs) are shows technological importance over the SPEs. The recent technique developed for solid polymer electrolytes is the dispersion of nano-size inorganic ceramic filler particles such as Al2O3, SiO2, TiO2, SnO2, ZnO etc. in the electrolyte systems [12-15]. Sodium salts exhibit several advantages such as these are available in low cost, this can be potentially used for industrial applications [16-19]. Hence in the present investigation, a new Na ion conducting salt NaBr has been selected as a dopant-salt to prepare the NCPEs. The SPE/ NCPE films are traditionally prepared by solution-cast/ sol-gel method. However, this is a time consuming procedure in the sense that it takes few days to weeks to cast completely dry films. Recently, for casting of ion conducting SPE/ NCPE films, a hot-press technique has been developed which shows several advantages such as it is relatively a least-expensive, much more rapid procedure etc. [20-24]. The present paper reports the synthesis and ionic conductivity studies of a new Na ion conducting nanocomposite polymer electrolytes (NCPEs): (1-x) [70PEO:30NaBr] + x SiO2, where 0 < x < 20 wt%. The ion conductivity enhancement in the present NCPEs are reported with the help of experimental measurement of some basic ionic parameters viz. ionic conductivity (σ), ionic mobility (μ), mobile ion concentration (n), ionic transference number (tion). Abstract Synthesis and ionic conductivity studies of a new Na ion conducting nano-composite polymer electrolytes (NCPEs): (1-x) [70PEO:30NaBr] + x SiO2, where 0 < x < 20 wt%, are reported. NCPE films have been synthesized using a recently developed hot-press technique in place of the traditional solution cast method. The highest ionic conductivity (σ) ( ~ 6.3 × 10 S.cm) has been determined at room temperature of the composition: [93(70PEO:30NaBr) + 7SiO2] and this has been referred to as optimum conducting composition (OCC). To explain the conductivity enhancement in the present NCPEs, ionic mobility (μ) and mobile ion concentration (n) measurements carried out with the help of dc polarization method. The ionic transference number (tion) of NCPE OCC only determined at room temperature to explain the ionic nature of the present systems.