Liquid-based Polymer Electrolyte Research Articles

Design and Fabrication of a High Performance Dssc Using Quasi-Solid-State Ionic Liquid-Based Conducting Polymer Electrolytes

Design and Fabrication of a High Performance Dssc Using Quasi-Solid-State Ionic Liquid-Based Conducting Polymer Electrolytes

Ionic liquid-based novel polymer electrolytes: electrical and thermal properties

New polymer electrolytes have been prepared from room temperature ionic liquid (IL) and poly(vinylidene fluoride)-hexafluoropropylene copolymer [PVdF-HFP]. The variation of thermal and electrical properties with varying polymer to IL concentration was investigated. The electrolytes had high thermal stabilities. The IL-PVdF-HFP electrolytes were freestanding, flexible films with room temperature conductivities of the order of 10−3 S cm−1. Increase in conductivity was found with increasing IL and also with increasing temperature. Increase in conductivity can be attributed to the fact that with increasing IL amorphicity increases as evident from XRD result. Dielectric studies showed decrease in relaxation time with increasing IL concentration indicating increase in polymer segmental motion which result in increase in conductivity.

Photoinitiated Polymerization of Methacrylate/Ionic Liquid Based Polymer Electrolytes: Effect of the Curing Sequence on the Electrochemical Properties

Polymer electrolytes have been widely investigated as promising candidates to prepare lithium ion batteries because of their excellent properties such as safety, mechanical stability and flexibility [1]. In this context, several polymerization techniques have been carried out and recently photo-initiated polymerization has become a well-established technology in this field [2,3]. Photo-initiated polymerization is a fast, low thermal impact and high spatial resolution method [4]. Furthermore, photo-initiated polymerization allow tailoring of the properties of the polymer since it can be carried out under a wide range of conditions, including variations in chemical composition (monomer structures, reaction mixture) and irradiation conditions (light intensity, fluence, temperature) [5]. In the present work, emphasis was devoted to the effect of the curing sequence on the electrochemical properties of methacrylate/ionic liquid based polymer electrolyte. The reaction mixture consisted of bisphenol A ethoxylate dimethacrylate (BisEMA, 29 wt.%), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, 16 wt.%), 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR13TFSI, 52 wt.%), and 2-hydroxy-2-methyl-1-phenyl-1-propanone (Darocur, 3 wt.%). The quaternary system exhibited a total miscibility behavior and consisted of a homogeneous mixture of all components, proven by differential scanning calorimetry (DSC) measurements before polymerization. Ultra violet (UV) photoinitiated polymerization was carried out with light intensities ranging between 0.3 and 50mW/cm². Photo-DSC measurements showed that the light intensity had no effect on the final conversion rate (100% in all cases), whereas it considerably influenced the polymerization rate and therefore the structural properties of the polymer. The resulting polymer electrolytes were investigated regarding their ionic conductivity. It was found that for the same reaction mixture, polymers obtained using very low light intensity presented at room temperature higher ionic conductivities (up to +50%) compared to those obtained at high light intensity. The temperature dependence of the ionic conductivity (figure 1) exhibited a Vogel–Tamman–Fulcher (VTF) type behavior in all considered photoinitiated polymerization conditions; furthermore it showed that light intensity affected the interactions between the ions and the polymer network. Particular attention was put on the investigation of the influence of the resulted polymer structures on the transport properties of the electrolytes using dynamic mechanical analysis (DMA) and solid state nuclear magnetic resonance (NMR). 1. M. Grünebaum, M. M. Hiller, S. Jankowsky, S. Jeschke, B. Pohl, T. Schürmann, P. Vettikuzha, A. C. Gentschev, R. Stolina, R. Müller, and H. D. Wiemhöfer, Prog. Solid State Ch. 42, 85 (2014) 2. S. H. Kim, K. H. Choi, S. J. Cho, S. Choi, S. Park, and S. Y. Lee, Nano Lett. 15, 5168, (2015) 3. E. H. Kil, K. Ho Choi, H. J. Ha, S. Xu, J. A. Rogers, M. R. Kim, Y. G. Lee, K. M. Kim, K. Y. Cho, and S. Y. Lee, Adv. Mater. 25, 1395 (2013) 4. C. Decker, Prog. Polym. Sci. 21, 593 (1996) 5. C. Decker, Macromol. Rapid Comm. 23, 1067 (2002) Figure 1

Enhancement in electrochemical properties of ionic liquid-based nanocomposite polymer electrolytes by 100 MeV Si9+ swift heavy ion irradiation

Swift heavy ion (SHI) irradiation has been used as a tool to enhance the electrochemical properties of ionic liquid-based nanocomposite polymer electrolytes dispersed with dedoped polyaniline (PAni) nanorods; 100 MeV Si9+ ions with four different fluences of 5 × 1010, 1 × 1011, 5 × 1011, and 1 × 1012 ions cm−2 have been used as SHI. XRD results depict that with increasing ion fluence, crystallinity decreases due to chain scission up to fluence of 5 × 1011 ions cm−2, and at higher fluence, crystallinity increases due to cross-linking of polymer chains. Ionic conductivity, electrochemical stability, and dielectric properties are enhanced with increasing ion fluence attaining maximum value at the fluence of 5 × 1011 ions cm−2 and subsequently decrease. Optimum ionic conductivity of 1.5 × 10−2 S cm−1 and electrochemical stability up to 6.3 V have been obtained at the fluence of 5 × 1011 ions cm−2. Ac conductivity studies show that ion conduction takes place through hopping of ions from one coordination site to the other. On SHI irradiation, amorphicity of the polymer matrix increases resulting in increased segmental motion which facilitates ion hopping leading to an increase in ionic conductivity. Thermogravimetric analysis (TGA) measurements show that SHI-irradiated nanocomposite polymer electrolytes are thermally stable up to 240–260 °C.