ORIGINAL PAPER Effect of nano-dispersed silica on the ion-conducting behavior of PMMA-based polymer gel electrolytes containing LiPF 6 Narinder Arora 1 & Simranjit Singh 1 & Rajesh Kumar 1 Received: 29 August 2016 /Revised: 22 January 2017 /Accepted: 20 February 2017 # Springer-Verlag Berlin Heidelberg 2017 Abstract Nano-sized silica poly(methylmethacrylate)-based gel electrolyte containing lithium hexafluorophosphate (LiPF 6 ) was synthesized by using different binary solvent mixture (propylene carbonate(PC) and dimethylformamide (DMF) in different volume ratio). Role of DMF in PC: Higher DMF content in PC-based electrolyte shows higher ionic conductivity at all polymer content and at wide temper- ature regions (10-70 °C). A small increment in ionic conduc- tivity at lower content of polymer in liquid/gel electrolyte was observed and having maximum conductivity of 13.12 mS/cm at 25 °C. Stability (mechanically and electrically), viscosity and ionic conductivity of gel electrolytes were improved with the addition of nano-sized silica at ambient temperature. Ionic conductivity of nano-sized silica-based gel electrolyte does not change much over 5 o –70 °C temperature range and is factor-wise only which make indispensable in different elec- trochemical devices. Also polymer gel electrolyte membranes as such and with dispersed silica nano-particles were charac- terized through scanning electron microscope to study the morphology of gel matrix. Keywords Gel electrolyte . Ionic conductivity . PMMA . Nano-sized silica . PC:DMF . Activation energy . SEM Introduction Electrolytes are the materials that separate into cations and anions, which disperse uniformly through the solvent and play the significant role of transmitting electrons and ions during charging and discharging processes [1]. It is one of the key components that define the battery ’ s performance—charging/discharging capacity, safety, cycling performance and current density. The basic desired qualities of electrolyte materials are listed as high ionic conductivity at wide range of temperature: increase the lithium ions diffusion and resist polarization during charging/discharging, good thermal stability: ensures the battery operation under appropriate temperature, wide electrochemical window: prevents side reactions between electrodes and electrolyte, better mechanical property: ease of manufacturing and enhanced safety with low cost, safety: high flashing point, non-toxic: environmental friendly, etc. [2–4]. In the early 1970s, development of numerous solid electrolytes (like crystalline/polycrystalline materials, glass or ceramic electrolytes, polymer gel electrolytes and gel electrolytes) in the field of solid state ionics was investigated. Polymer electrolytes are not as brittle as sol- id crystalline or glass electrolytes and can form good in- terfacial contact with electrode materials. Other advan- tages of polymer electrolytes are its high energy density, volumetric stability, light weight, solvent-free condition, easy handling, wide electrochemical stability windows and no internal shorting [5–8]. In the past two decades, poly(ethylene oxide) (PEO)-based electrolytes were among the major polymer host matrix used and significant research efforts have been made on their development. The conduction of PEO-based electrolytes is mainly through the complexes between PEO-lithium salt, which could be easily casted as thin membranes. However, due to PEO having high degree of crystallinity, the ionic con- ductivity of PEO-based electrolytes is low and varies from 10 -8 S cm -1 to 10 -4 S cm -1 for temperature in-between 40 and 100 °C [9, 10]. Ito et al. observed that the ionic * Narinder Arora n_arora2k@yahoo.com 1 P.G. Dept. of Physics, D.A.V. College, Amritsar, Pb 143001, India Ionics DOI 10.1007/s11581-017-2038-5