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In the present article, we have studied the effect of the salt concentration (LiPF 6 ) on transport properties and ion dynamics of blend solid polymer electrolyte (PEO-PAN) prepared by solution cast technique. Fourier transform infrared (FTIR) spectroscopy confirms the presence of microscopic interactions such as polymer-ion and ion-ion interaction evidenced by a change in peak area of anion stretching mode. The fraction of free anions and ion pairs obtained from the analysis of FTIR implies that both influence the ionic conductivity with different salt concentration.The complex dielectric permittivity, dielectric loss, complex conductivity have been analyzed and fitted in the entire frequency range (1 Hz-1 MHz) at room temperature. The addition of salt augments the dielectric constant and shift of relaxation peak in loss tangent plot toward high frequency indicates a decrease of relaxation time. We have implemented the Sigma representation (σ'' vs. σ') for solid lithium ion conducting films which provide better insight toward understating of the dispersion region in Cole-Cole plot (ε'' vs. ε') in lower frequency window. The dielectric strength, relaxation time and hopping frequency are in correlation with the conductivity which reveals the authenticity of results. Finally, the ion transport mechanism was proposed for getting the better understanding of the ion migration in the polymer matrix.

In this review, latest updates in the poly (ethylene oxide) based electrolytes are summarized. The ultimate goal of researchers globally is towards the development of free standing solid polymeric separator for energy storage devices. This single free standing solid polymeric separator may replace the liquid and separator (organic/Inorganic) used in existing efficient/smart energy technology. As an example polyethylene oxide (PEO) consist of an electron donor rich group which provides coordinating sites to the cation for migration. Owing to this exclusive structure PEO exhibits some remarkable properties such as; low glass transition temperature, excellent flexibility and ability to make complexation with various metal salts which are unattainable by another polymer host. Hence, the PEO is the most emerging candidate that have been examined or is currently under audition for application in energy storage devices. So, this review article first provides the detailed study of the PEO properties, characteristic of constituents of polymer electrolyte and suitable approaches for the modification of polymer electrolytes. Then, the synthesization and characterizations techniques are outlined. The structures, characteristics, and performance during charge-discharge of four types of electrolyte/separators which are Liquid, Plasticized, and dispersed/intercalated electrolyte are highlighted. The suitable ion transport mechanism proposed by researchers in different renowned group have been discussed for better understanding of the ion dynamics in such systems.Keywords: polyethylene oxide, constituents of polymer electrolytes, structural and microstructural properties, electrochemical properties summarizes the requirements for selection of electrolyte cum separator for efficient lithium-ion battery system [4].At, present, LIB is the ideal choice for the automotive sector by Companies including Tesla Inc. and Volkswagen AG due to ease of transportation, environmentally friendly, less cost [5]. Allied Market Research published a report entitled, "World Lithium-Ion Battery Market: Opportunities and Forecasts, 2015-2022" and the main point was that the global LIB market is expected to generate revenue of $46.21 billion by 2022, with a CAGR of 10.8% during the forecast period (2016)(2017)(2018)(2019)(2020)(2021)(2022). At a 37 percent revenue share, Li-ion is the battery of choice for portable devices and the electric vehicles. There are no other systems till now that threaten the market of LIB today [figure 2].Recently in 2017, John Goodenough, inventor of Li-ion battery has developed the first all-solid-state battery cells using sodium-or lithium-coated glass electrolyte and claimed that new battery cells have three times more energy density (1,200 charge-discharge cycles) in comparison to existing rechargeable batteries. He concluded that they store and transmit energy at temperatures (-20 o C to 60 o C) lower than traditional lithium-ion packs and can be made using globally abundant supplies of sodium. One advantage of this...

In the present work, the effect of different nanofiller (BaTiO3, CeO2, Er2O3 or TiO2) on blend solid polymer electrolyte comprising of PEO and PVC complexed with bulky LiPF6 have been explored. The XRD analysis confirms the polymer nanocomposite formation. FTIR provides evidence of interaction among the functional groups of the polymer with the ions and the nanofiller in terms of shifting and changing peak profile. The highest ionic conductivity is ~2.3×10 -5 S cm -1 with a wide electrochemical stability window of ~3.5 V for 10 wt. % Er2O3. The real and imaginary part of dielectric permittivity follows the identical trend of the decreasing value with increase in the frequency. The particle size and the dielectric constant shows an abnormal trend with different nanofiller. The ac conductivity follows the universal power law. An effective mechanism has been proposed to understand the nanofiller interaction with cation coordinated polymer in the investigated system. storage/conversion devices must have (a) high ionic conductivity; (b) electrochemical stability window (>4 V); (c) low melting point; (d) high boiling point; (e) high chemical stability; (f) nontoxicity; (g) low cost and good compatibility with electrodes. Solid polymer electrolyte (SPEs) plays a dual role as an electrolyte as well as a separator which keeps both electrodes separate and avoids the user from using a spacer as in liquid electrolyte system. The first report on ionic conduction was given by P. V. Wright [5] and Fenton et al [6] in 1973 and it was concluded that polymer host dissolved with an alkali metal salt results in an ionic conductive system. The first application of novel polymer electrolyte in batteries was announced by Armand and his co-workers in 1978 [7]. Most devices are based on liquid/gel polymer electrolytes due to their high ionic conductivity (10 -3 -10 -2 Scm -1 ) and compatible with electrodes. But poor mechanical strength, freezing at low temperature, leakage and flammable nature limits their application in commercial use. This motivates the researchers toward better replacement of liquid polymer electrolyte with a solvent free polymer electrolyte having high ionic conductivity, leak proof, flexibility, wide electrochemical window, good mechanical strength, light weight and ease of preparation [8-10]. Solid polymer electrolytes (SPEs) fulfill all above requirements and have attracted researchers globally towards development for their potential application in portable electronics and electrochemical devices [11]. The commonly used host polymer for preparation of polymer nanocomposite films (PNCs) is PEO [12], PAN [13], PMMA [14], PEMA [15] and PVC [16]. Out of aforesaid host polymers, polyethylene oxide (PEO) is undoubtedly the best host polymer used as SPEs with strong, unstrained C-O, C-C, C-H bonds and it has high dielectric constant, easy availability, and high ionic conductivity in amorphous phase, low glass transition temperature, high flexibility, and good dimensional and chemical stability. But PEO possesses low ion...

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In this paper, we have studied the structural, microstructural, electrical, dielectric properties and ion dynamics of a sodium-ion-conducting solid polymer electrolyte film comprising PEO-NaPF+  x wt. % succinonitrile. The structural and surface morphology properties have been investigated, respectively using x-ray diffraction and field emission scanning electron microscopy. The complex formation was examined using Fourier transform infrared spectroscopy, and the fraction of free anions/ion pairs obtained via deconvolution. The complex dielectric permittivity and loss tangent has been analyzed across the whole frequency window, and enables us to estimate the DC conductivity, dielectric strength, double layer capacitance and relaxation time. The presence of relaxing dipoles was determined by the addition of succinonitrile (wt./wt.) and the peak shift towards high frequency indicates the decrease of relaxation time. Further, relations among various relaxation times ([Formula: see text]) have been elucidated. The complex conductivity has been examined across the whole frequency window; it obeys the Universal Power Law, and displays strong dependency on succinonitrile content. The sigma representation ([Formula: see text]) was introduced in order to explore the ion dynamics by highlighting the dispersion region in the Cole-Cole plot ([Formula: see text]) in the lower frequency window; increase in the semicircle radius indicates a decrease of relaxation time. This observation is accompanied by enhancement in ionic conductivity and faster ion transport. A convincing, logical scheme to justify the experimental data has been proposed.

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