Investigation of new ion-conducting ORMOLYTES: Structure and properties (original) (raw)
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NMR Study of Ion-Conducting Organic-Inorganic Nanocomposites Poly(ethylene glycol)-Silica-LiClO4
Macromolecules, 2000
Hybrid organic-inorganic ionic conductors, also called ormolytes, were obtained by dissolution of LiClO 4 into silica/poly(ethylene glycol) matrices. Solid-state nuclear magnetic resonance (NMR) was used to probe the inorganic phase structure ( 29 Si) and the effects of the temperature and composition on the dynamic behavior of the ionic species ( 7 Li) and the polymer chains ( 1 H and 13 C). The NMR results between -100 and +90°C show a strong correlation with ionic conductivity and differential scanning calorimetry experiments. The results also demonstrate that the cation mobility is assisted by segmental motion of the polymer, which is in agreement with the results previously reported for pure poly(ethylene oxide), PEO, electrolytes.
Chemistry of Materials, 2001
Hybrid organic-inorganic ionic conductors, also called ormolytes (organically modified electrolytes), were obtained by dissolution of LiClO 4 in siloxane-poly(propylene glycol) matrixes. The dynamic features of these nanocomposites were studied and correlated to their electrical properties. Solid-state nuclear magnetic resonance (NMR) spectroscopy was used to probe the effects of the temperature and nanocomposite composition on the dynamic behaviors of both the ionic species (7 Li) and the polymer chains (13 C). NMR, dc ionic conductivity, and DSC results demonstrate that the Li + mobility is strongly assisted by the segmental motion of the polymer chain above its glass transition temperature. The ac ionic conductivity in such composites is explained by use of the random free energy barrier (RFEB) model, which is in agreement with their disordered and heterogeneous structures. These solid ormolytes are transparent and flexible, and they exhibit good ionic conductivity at room temperature (up to 10-4 S/cm). Consequently, they are very promising candidates for use in several applications such as batteries, sensors, and electrochromic and photoelectrochemical devices.
Transport properties of a new Li 1 ion-conducting ormolyte: (SiO 2 –PEG)–LiCF 3 SO 3
The transport properties of a new fast Li 1 ion-conducting sol-gel-derived ormolyte, (SiO 2 -10 wt% PEG)-[Li/O] LiCF 3 SO 3 , with [Li/O]~0-0.1 (mol/mol), is reported. The composition with [Li/O]~0.04 exhibited the highest conductivity (s 25 uC~1 6 10 24 S cm 21 ), with an enhancement of 10 3 over the host matrix (SiO 2 -10 wt% PEG xerogel), and has been found to be the 'optimum conducting composition'. Direct determination of Li 1 ion mobility (m) and mobile ion concentration (n) revealed that the enhancement was due to the increase in both m and n. Studies of the variation of s, m, and n versus temperature indicated that the system shows Arrhenius-type behavior. The activation energy and energies of migration and formation were evaluated from their respective Arrhenius plots. Measurement of the ion transference number (t ion ) confirmed that the ions are the sole charge carriers in the system. These results are discussed in the light of existing theories.
Electrochimica Acta, 2003
This paper describes the synthesis and characterization of three-dimensional hybrid inorganic Á/organic networks prepared by a polycondensation reaction between Zr(O(CH 2) 3 CH 3) 4 and polyethylene glycol 400 (PEG400). Eleven hybrid networks doped with varying concentrations of LiClO 4 salt were prepared. On the basis of analytical data and FT-Raman studies it was concluded that these polymer electrolytes consist of inorganic Á/organic networks with zirconium atoms bonded together by PEG400 bridges. These polymers are transparent with a solid rubber consistency and are very stable under inert atmosphere. Scanning electron microscopy revealed a smooth glassy surface. X-ray fluorescence microanalysis with energy dispersive spectroscopy demonstrated that all the constituent elements are homogeneously distributed in the materials. Thermogravimetric measurements revealed that these materials are thermally stable up to 262 8C. Differential Scanning Calorimetry measurements indicated that the glass transition temperature T g of these inorganic Á/organic hybrids varies from (/43 to (/15 8C with increasing LiClO 4 concentration. FT-Raman investigations revealed the TGT (T 0/trans , G0/gauche) conformation of polyether chains and allowed characterization of the types of ion-ion and ion Á/polymer host interactions in the bulk materials. The conductivity of the materials at different temperatures was determined by impedance spectroscopy over the 20 Hz Á/1 MHz frequency range. Results indicated that the materials conduct ionically and that their ionic conductivity is strongly influenced by the segmental motion of the polymer network and the type of ionic species distributed in the bulk material. Finally, it is to be highlighted that the hybrid network with a n Li /n O molar ratio of 0.0223 shows a conductivity of ca. 1)/10 (5 S cm (1 at 40 8C.
Effect of salt nature on structure and ionic conductivity of sodium-doped siloxane–PPO ormolytes
Journal of the European Ceramic Society, 2005
Siloxane-polyoxypropylene (PPO) hybrids obtained by the sol-gel process and containing short polymer chain have been doped with different sodium salts NaX (X = ClO 4 , BF 4 or I). The effect of the counter-ion (X) on the chemical environment of the sodium ions and on the ionic conductivity of these hybrids was investigated by 23 Na NMR, small angle X-ray scattering (SAXS), complex impedance, Raman spectroscopy and differential scanning calorimetry (DSC). Results reveal that the different sodium salts have essentially the same effect on the nanoscopic structure of the hybrids. The formation of immobile Na + cations involved in NaCl-like species could be minimized by using a low amount of HCl as hydrolytic catalyst. The differences in the ionic conductivity of hybrids doped with different sodium salts were correlated with the proportion of Na ions solvated by ether-type oxygen of the polymeric chains and by the carboxyl oxygen located in the urea groups of the PPO chain extremities.
Synthesis and Ion Conductivity Studies of Na+ Ion Conducting Nano Composite Polymer Electrolytes
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 (ƒÐ) ( ~ 6.3 ~ 10-5 S.cm-1) 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 (ƒÊ) 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.
Sol-gel derived Li-ion conducting polymer electrolytes
2000
Organic-inorganic hybrids have recently become a remarkable family of amor phous polymer materi- als with promising potential applications. In the present study, sol-gel derived organic-inorganic hybrid electrolytes doped with lithium salts (LiCl, LiClO 4) were produced from inorganic and organic precursors such as tetraethyl orthosilicate, poly(ethylene oxide), poly(ethylene glycol), propylene oxide, propylene carbonate, ethylene glycol, and 1,2-propylene glycol. The hybrid
2012
The synthesis, diffraction patterns, thermal stability, and ionic conductivity properties of methacrylate-type polymers are analyzed here to assess their feasibility as polymer electrolytes. From the parent polymer, poly (N,N-dimethylaminoethylmethacrylate), herein labeled PDMAEMA, a protonated derivative was used to prepare polymer/Montmorillonite nanocomposites with various clay contents (1, 3, and 5 wt %). AC spectroscopy provided the ionic conductivity data for the polymers and clay-polymer nanocomposites. Evidences of nanocomposite formation are shown using transmission electron microscopy and wide-angle X-ray diffraction.
Synthetic Metals, 1999
Correlation between ionic conduction and structural transition of poly(propileneglycol)-silica composite, complexed with lithium salt, was performed by dc and ac electrical measurements. thermal analysis (DSC) and nuclear magnetic resonance spectroscopy in the 200 to 300 K temperature range. At about 285 K an abrupt increase in the dc conductivity and a change of ac conductivity behaviour were observed. Around this temperature it was also observed a linewidth narrowing 7Li NMR while DSC thermograms shows a glass transition T, immediately followed by a melt point T,. The dc conductivity-temperature behaviour was explained by the Vogel-Tamman-Ftilcher model and ac by the Random Free Energy Barrier Model.
Polymer, 2010
A synthesis route for preparing highly conductive solid organiceinorganic hybrid electrolytes has been developed by using cyanuric chloride as the coupling core to react with diamino-terminated poly(oxyalkylene) triblock copolymers, followed by cross-linking with an epoxy alkoxysilane 3-glycidyloxypropyl trimethoxysilane via a sol-gel process. The present hybrid electrolyte with a [O]/[Li] ratio of 32 was found to be the most conductive, reaching a maximum lithium ion conductivity of 6.8 Â 10 À5 Scm À1 at 30 C. The Li-ion mobility was determined from 7 Li static NMR line width measurements and correlated with their ionic conductivities. The onset of 7 Li line narrowing was closely related to the T g of the hybrid electrolytes as measured by DSC experiments. Thus, the motions of the lithium cations are strongly coupled with the segmental motion of the polymer chains, which is in line with the Vogel-Tamman-Fulcher behavior as observed in ionic conductivity.