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FTIR spectroscopic study of the interaction between NH4+ and DMSO in Nafion
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Nafion-NH4+ membranes plasticized with dimethyl sulfoxide (DMSO and DMSO-d6) have been investigated at room temperature using the vacuum ATR-FTIR and FTIR absorption spectroscopic technique in the range 50–4000 cm−1. The amount of the plasticizer corresponds to the molecular ratio n = DMSO/NH4+ = 2.7–13.8. The mutual association of free DMSO molecules in Nafion leads to appearance of weak band at 86 cm−1 assigned to dipole-dipole interactions. Also the Raman spectra of dry Nafion-NH4+ membranes were investigated.
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... With the increase of DMSO proportion, the C=O Free peak of formamide at 1720 cm À 1 gradually weakens while the C=O Association peak slowly strengthens in the mixed solution, [56][57] and the À CH peaks of DMSO (3000&2910 cm À 1 ) in SE-PBI is strengthened. [58] Both À CH peaks of formamide (2880 cm À 1 ) in solution and membrane show a red-shift with the increase of DMSO proportion. These changes of FT-IR peaks are evidence of the hydrogen bonds forming between DMSO and formamide. ...
The tightly connected structure of polybenzimidazole (PBI) membrane can be relaxed by solvent/nonsolvent solution to achieve a high proton conductivity for vanadium redox flow battery (VRFB). However, the nature behind the solvent/nonsolvent strategy is not unraveled. This work proposes a guideline to analyze the effect of PBI membrane relaxing formulas based on the interactions between different components in membranes. The supreme‐efficient PBI membrane derived by the DMSO/formamide formula according to the guideline displays a marvelous performance for VRFB, with the proton conductivity boosted by 4300 % (from 1.93 to 83.33 mS cm⁻¹), and VRFB assembled with this membrane achieves an outstanding energy efficiency of 82.5 % under 200 mA cm⁻². Moreover, this work profoundly unravels the structure, property and performance relationship of PBI membrane, which is of great value for the development of membranes.
... As shown in Figure 1d, the CÀ H peaks of PBI (2920 and 2850 cm À 1 ) are gradually replaced by the CÀ H peaks of DMSO (3000 and 2910 cm À 1 ) with the increase of DMSO proportion. [31] This phenomenon indicates that the increase in DMSO proportion of mixed solution allows the PBI membrane to absorb more DMSO. In addition, the À NÀ H stretch peak (near 3600 cm À 1 ) of PBI gradually disappears with the increase of DMSO proportion, [32] suggesting that the À NÀ structure forms hydrogen bonds with DMSO molecules. ...
The tightly bonded structure of polybenzimidazole (PBI) membrane is the origin of its poor proton conductivity, which severely hinders achieving a cost‐effective membrane for vanadium redox flow battery (VRFB). It desires a strategy to relax the membrane structure to significantly improve the proton conductivity and maintain its structure stability. Therefore, this work proposes a novel strategy through regulating molecular interactions within PBI membrane to loosen up the structure of PBI membrane and dramatically enhance the proton conductivity. The interactions in PBI membrane are switched by DMSO/water and acid through sequentially treating membrane with these solutions. The efficient PBI membrane prepared using this strategy demonstrates an outstanding performance for VRFB, with the proton conductivity enhanced by 3850 % (from 1.9 to 76.3 mS cm⁻¹), and VRFB achieves a high energy efficiency of 80.5 % under 200 mA cm⁻². More importantly, this work shed lights on the structure‐property relationship of PBI membrane, and the mechanism in enhancing proton conductivity is unraveled, which is of great significance for the development of VRFB membranes.
... Most peaks did not show differences in their wavelength numbers (Table S5), except for the peak at 2804 cm − 1 (C-H) of the new membrane, which disappeared in the used membrane. Peaks between 2902 cm − 1 and 2989 cm − 1 were verified only at the used membrane, which may be associated with the interaction between the Fumasep-NH 4 + from the NH 4 + sorbed, as verified by Karelin et al. [34] for Nafion-NH 4 + between 2870 ± 10 cm − 1 and 3212 ± 4 cm − 1 , or due to the presence of Ca at both surfaces, as shown in Table S3. The unchanged values of most peaks of the Fumasep despite the presence of NH 4 + and other species at its surfaces agree with the Table S6, some peaks initially present at the new membrane, such as at 3441 cm − 1 (ν(O-H) of the bounded water), 1635 cm − 1 (C-H stretching), and 1601 cm − 1 (C-H stretching vibration), disappeared or were shifted after DD, which may have occurred due to the NH 4 + sorption or fouling, while some peaks appeared after the process. ...
Polyhydroxyalkanoates (PHA) are promising biobased and biodegradable alternatives to the petroleum-based plastics. For their production, controlling cell growth is crucial and can be achieved by limiting nutrients, such as ammonium. The use of Donnan dialysis (DD) has been considered for this purpose. However, the effects of long–term DD fermentative operations need to be evaluated since fouling and sorption phenomena can affect the process performance. In this study, DD operations were performed over 10 consecutive batches to separate ammonium from a real fermented stream derived from an acidogenic fermentation process using cation-exchange membranes with distinct properties (a homogenous Fumasep FKS–PET-130 and a heterogenous Ralex CMH-PES) and NaCl or HCl aqueous receiver solutions. A cleaning procedure with acidic and alkaline solutions was proposed for the Ralex. It was verified that sorption and fouling phenomena occurred on/inside both membranes using a NaCl solution as receiver. This occurred more intensely with the Ralex, thus reducing the ammonium percent extraction from 55% (first batch) to approximately 40% in the subsequent batches. On the other hand, Fumasep exhibited higher percent extractions, and its values remained constant at around 65% along the batches when only rinsed with distilled water. The proposed cleaning procedure for Ralex effectively regenerated this membrane and increased the subsequent ammonium percent extractions. However, the acidic and/or alkaline solutions formed cavities on/in the membrane. The use of a HCl solution as receiver led to a lower reduction in the percent extraction throughout the batches when compared to NaCl, but the acidic receiver solution also damaged the membrane. It is suggested the use of the Fumasep membrane for the application evaluated herein or that a milder cleaning procedure is developed and applied for the Ralex membrane.
... The weak solutesolvent interaction causes a rapid reaction between PbBr 2 and CsBr, leading to the formation of massive PVSK grains on the sample surface. For the DMSO, a new absorption peak located at 1,013 cm −1 appears in the PbBr 2 solution (Fig. S5C), which originates from the PbBr 2 ·DMSO intermediate adducts [38,39]. ...
The combination of all-inorganic perovskites (PVSKs) and polymers allows for free-standing flexible optoelectronic devices. However, solubility difference of the PVSK precursors and concerns over the compatibility between polymer carriers and PVSKs imply a great challenge to incorporate different kinds of PVSKs into polymer matrices by the same manufacturing process. In this work, PVSK precursors are introduced into poly(2-hydroxyethyl acrylate) (PHEA) hydrogels in sequence, in which the PVSK-gel composites are achieved with full-color emissions by simply varying the precursor species. Moreover, it is found that CsBr has a higher interaction energy with the (111) plane of CsPbBr3 than the (110) plane; thus, the CsPbBr3 crystals with a shape of truncated cube and tetragon are observed during the CsPbBr3–Cs4PbBr6 phase transition over time. The PVSK-gel composites feature excellent bendability, elasticity, and stretchable deformation (tensile strain > 500%), which allows for 3D printing emissive customized stereoscopic architectures with shape-memory features.
... The Fourier Transform Infrared (FTIR) reading technique has been used to measure the sample surface absorbance in evaluating plastic detectors. The FTIR has been applied recently in several areas [15][16][17][18][19][20]. ...
Dosimetric evaluation is indicated for material characterization seeking to identify possible applications; still, proper preprocessing techniques are critical features of this process. This work aimed to determine the linearity response of plastic samples irradiated with gamma rays using the Fourier Transform Infrared (FTIR) measurements. The plastic samples were analyzed using Derivatives and Principal Component Analysis (PCA) methods. They applied linear and Principal Component Regression (PCR) methods to obtain linearity. The methods obtained good results for linearity and also showed the evolution of each technique. In conclusion, the results indicate that the applied methods can be useful in radiation physics and for plastic samples as interesting potential radiation detectors.
... A mammary gland breast cancer cell line (MCF-7), human hepatocellular carcinoma cell line (HepG-2), and colon carcinoma cell line (Caco-2) were all maintained at the Cell Culture Lab, Egyptian Organization for Biological Products and Vaccines (VACSERA Holding Company) Cairo, Egypt. SRB assays were based on the uptake of the negatively charged pink amino-xanthine dye [24]. Similarly, cytotoxic evaluations of HA and shells for two types of normal cells (e.g., h-MSC and epithelial cells) were carried out. ...
Hydroxyapatite (HA) nanoparticles derived from mussel shells were prepared using the wet precipitation method and were tested on human mesenchymal and epithelial cells. Shells and HA powder were characterized via X-ray diffraction analysis (XRD) and scanning electron microscopy along with energy dispersive X-ray spectroscopy (SEM/EDX), high resolution transmission electron microscopy (HR-TEM) and Fourier transform infrared spectroscopy (FTIR). The in vitro cytotoxic properties of HA and mussel shells were determined using sulphorhodamine B (SRB) assays for MCF-7 cells (HepG2) and colon (Caco-2) cells. Cell viability tests confirmed the nontoxic effects of synthesized HA and mussel shells on human mesenchymal stem cells (h-MSCs) and epithelial cells. Toxicity values were less than 50% of the cell's validity ratio based on analyses using different concentrations (from 0.01 to 1,000 μg). The results indicate that MSC and epithelial cell attachment and proliferation in the presence of both HA and shell occurred.
The proliferation capability was established after 3 and 7 days. SEM images revealed that stem cells and epithelial cells attached to the scaffold indicated full and complete integration between the cells and the material. It seems that due to the ion exchange between bovine serum albumin solutions (BSA) and HA, the FTIR data confirmed an increase in the amide I and amide II bands, which indicates the compatibility of the BSA helix structure. This study sheds light on the importance of merging stem cells and nanomaterials that may lead to improvements in tissue engineering to develop novel treatments for various diseases.
... [36,37]. Compared with parent NaY, an absorption peak near 1400 cm −1 is found in NH 4 HF 2etched NaY or NH 4 HF 2 -etched NaY-s-2(before 550°C heat treatment), which is ascribed to the characteristic peak of NH 4 + [38,39]. In particular, this peak in NH 4 HF 2 -etched NaY-s-2 (before 550°C heat treatment) is weak, indicating that the most of NH 4 + cations in Y zeolites are replaced by the surfactant cation. ...
Volatile organic compounds have seriously affected the natural environment and human health, and adsorption is one of the most effective method for controlling VOCs pollution. In this work, the NH4HF2-etched NaY-s-x zeolites with intracrystalline mesoporosity are obtained via the surfactant-templating process in weak base NH4OH solution. The morphology, microstructure, and toluene adsorption property of as-prepared hierarchical Y zeolites are systematically characterized. It is found that the structural and textural properties of NH4HF2-etched NaY samples are significantly changed by the simple surfactant-templated approach and the large-sized mesopores inside NH4HF2-etched NaY sample disappear to form the surfactant-templated mesoporosity with a size of ~4 nm. It is demonstrated that the intracrystalline mesoporosity obviously improves the toluene molecular adsorption properties of zeolite samples. Moreover, the mechanism of the surfactant-templating process is elucidated.
... A detailed study of NH 4 + ·n DMSO and NH 4 + ·n DMSO-d6 solvates in Nafion by ATR FTIR and FTIR absorption spectroscopy is presented in work. 56 SAXS.-The SAXS curves of all the studied films exhibit two characteristic peaks (Figure 4). ...
The work addresses the properties of electro-transport in highly ion-conductive polymer electrolytes based on Nafion-115 membranes in the NH4+ ionic form plasticized with dimethyl sulfoxide (DMSO). The ionic conductivity and the activation energy of the conductivity were found to exhibit three types of behavior as a function of the plasticizer. The first region (when the ratio of moles of DMSO molecules per mole of NH4+ (n) < 6) is characterized by low conductivity values (10^−7– 10^−4 S*cm^−1) and high energy barriers (0.76 and 0.43 eV for n = 0 and 2.6, respectively). In the second region (n = 6–12), the electrolyte has a high conductivity and a low activation energy of conductivity (∼0.1 eV). With an increase in the DMSO content, the conductivity appreciably increases and reaches ∼ 0.4 mS*cm^−1. In the third region (n ≥ 12) the transport parameters are comparable to those of the second region, but the conductivity is practically independent of the DMSO content. The observed behavior was explained on the basis of the results obtained with the help of IR spectroscopy, differential scanning calorimetry, small-angle X-ray scattering and quantum-chemical modeling
Histidine (His) is a semi-essential amino acid and a unique key neurotransmitter involved in numerous physiological processes. An excessive or deficient amount of His in the body can lead to...
Amidst these growing sustainability concerns, producing NH4⁺ via electrochemical NO3⁻ reduction reaction (NO3RR) emerges as a promising alternative to the conventional Haber‐Bosch process. In a pioneering approach, this study introduces Ru incorporation into Co3O4 lattices at the nanoscale and further couples it with electroreduction conditioning (ERC) treatment as a strategy to enhance metal oxide reducibility and induce oxygen vacancies, advancing NH4⁺ production from NO3RR. Here, supported by a suite of ex situ and in situ characterization measurements, the findings reveal that Ru enrichment promotes Co species reduction and oxygen vacancy formation. Further, as evidenced by the theoretical calculations, Ru integration lowers the energy barrier for oxygen vacancy formation, thereby facilitating a more energy‐efficient NO3RR‐to‐NH4⁺ pathway. Optimal catalytic activity is realized with a Ru loading of 10 at.% (named 10Ru/Co3O4), achieving a high NH4⁺ production rate (98 nmol s⁻¹ cm⁻²), selectivity (97.5%) and current density (≈100 mA cm⁻²) at −1.0 V vs RHE. The findings not only provide insights into defect engineering via the incorporation of secondary sites but also lay the groundwork for innovative catalyst design aimed at improving NH4⁺ yield from NO3RR. This research contributes to the ongoing efforts to develop sustainable electrochemical processes for nitrogen cycle management.
We used a combination of in situ TPV measurements and DFT calculations for the first time to understand the carrier transfer process at a CO 2 /Cs 2 AgBiBr 6 gas–solid interface.
Approximately up to 2 billion tons of solid waste are generated globally each year. The resource recovery utilization of solid waste has become an urgent need, which can not only greatly improve environmental pollution but also alleviate the problem of resource shortage. In this work, artificial marble waste (AMW) was introduced into polylactic acid/polyvinyl alcohol/polyethylene glycol (PLA/PVA/PEG) composites to develop AMWs-reinforced biodegradable sustainable composites (BSC). AMWs-reinforced BSC exhibited excellent strength, toughness, processability, and can withstand more than 8000 times its weight. Notably, AMWs significantly accelerated the degradation rate of the composite. Compared with the BSC without AMWs, the weight loss of 8%AMWs-reinforced BSC was increased by nearly 20% after 28 days of degradation. The promising application of AMWs-reinforced BSC in next-generation biodegradable sustainable packaging (BSP) was demonstrated. This not only enabled high value-added utilization of AMWs but also greatly accelerated the degradation rate of plastic packaging and reduced white pollution. The work effectively promotes resource utilization and environmental improvement through resource recovery and accelerated degradation of solid wastes, providing new ideas to solve resource shortages and environmental problems.
The present study deals with the enhancement of proton transport and conduction properties of solid polymer electrolyte (SPE)-based carboxymethyl cellulose (CMC) blended with polyvinyl alcohol (PVA) doped with ammonium nitrate (NH4NO3) and plasticized with various compositions of polyethylene glycol (PEG). The SPE system was successfully prepared using an economical method, the solution casting technique, and analysed by Fourier transform infrared spectroscopy and electrical impedance spectroscopy. The infrared spectra show that interaction had occurred at O–H and COO− from CMC when PEG was added which prevailed the enhancement of ion dissociation. Glass transition measurement highlighted that the interaction between CMC–PVA–NH4NO3 and ethylene carbonate at 8 wt% give the most plasticization effect that achieved the lowest Tg. The highest conductivity of the SPE system achieved at ambient temperature was 1.70 × 10−3 S cm−1 for a non-plasticized sample, and further enhanced to 3.00 × 10−3 S cm−1 when 8 wt% PEG was incorporated into the SPE system. The sample with the highest conductivity was found to obey the Arrhenius behaviour with a function of temperature. The ionic conductivity of the SPE system was shown to be primarily influenced by a number of ions (η), ion mobility (μ) and diffusion coefficient (D).
The Nafion-117 membranes in the Li⁺ form with pore-intercalated aprotonic organic solvents were prepared. The prepared materials were characterized by IR, impedance, and ⁷Li NMR spectroscopy. The solvent uptake of the membranes is shown to be controlled by the composition of organic solvents and their mixtures as well as by the conditions of the preliminary treatment of the initial membranes. For the Nafion-117 membrane, the degree of solvation can be improved by the preliminary treatment with alcohols, especially by the thermal treatment in methanol. Conductivity of the membranes is shown to increase with increasing content of the sorbed solvents. The best conductivity at 25 °C (2.5 × 10⁻³ and 1.6 × 10⁻³ S cm⁻¹) was attained for the electrolytes based on the Nafion-117 membrane in lithium form with sorbed ethylene carbonate-propylene carbonate and ethylene carbonate-dimethoxyethane mixtures, respectively.
The products of solvation of lithiated Nafion with dimethylsulfoxide (DMSO) have been studied
by ATR IR spectroscopy in the frequency range of 50–4000 cm–1 in a vacuum at room temperature. Degree
of solvation n = DMSO/Li has been varied in a range of 1.5–18.4. Based on analysis of the dependence of the
spectral parameters on the n value, it has been concluded that the test samples contain DMSO molecules of
two types. The first type includes molecules coordinated to the lithium ion through the formation of the
metal–oxygen bond, and the second is DMSO molecules associated by intermolecular bonds similar to those
in the liquid DMSO phase. The structure of the salt depends on n: the changes are attributed to the reorientation
of polymer chain units. The coordination number of lithium has been estimated at four. It has been
shown that the IR data are consistent with the data on the conductivity of lithiated Nafion membranes as a
function of DMSO content, according to which the simplest transport unit is the tetrasolvate [Li(DMSO)4]+.
At temperatures below 0°C, all the samples exhibit an abrupt change in conductivity, which is attributed to
the freezing of DMSO in the membrane matrix.
The first working Mg rechargeable battery prototypes were ready for presentation about 13 years ago after two breakthroughs. The first was the development of non-Grignard Mg complex electrolyte solutions with reasonably wide electrochemical windows in which Mg electrodes are fully reversible. The second breakthrough was attained by demonstrating high-rate Mg cathodes based on Chevrel phases. These prototypes could compete with lead–acid or Ni–Cd batteries in terms of energy density, very low self-discharge, a wide temperature range of operation, and an impressive prolonged cycle life. However, the energy density and rate capability of these Mg battery prototypes were not attractive enough to commercialize them. Since then we have seen gradual progress in the development of better electrolyte solutions, as well as suggestions of new cathodes. In this article we review the recent accumulated experience, understandings, new strategies and materials, in the continuous R&D process of non-aqueous Mg batteries. This paper provides a road-map of this field during the last decade.
Nafion membranes plasticized with dimethyl sulfoxide (DMSO) have been examined at room temperature using the vacuum ATR - FTIR spectroscopic technique in the range 50–4000 cm− 1. The amount of the plasticizer corresponds to the molecular ratio n = DMSO/H+ = 1.2, 2.3, 4.8, 7.0, 9.7 and 13.3. The medium intensity band with two maxima at 780 and 853 cm− 1 have been assigned to the ν(SO) stretching vibrations of the H+(DMSO)2 complex. The possible reason of ν(SO) splitting is symmetry decrease of hydrogen bond under the influence of the anion group single bondSO3− electric field. Whereas the mutual association of free DMSO molecules in Nafion leads to appearance of weak band at 86 cm− 1 assigned to the dipole-dipole interactions.
Single-ion conducting polymer electrolytes have received great attention due to their potential applications in electrochemical energy sources. In this work we have in detail studied features of ion transport of alkali metal ions in the polymer electrolytes based on Nafion plasticized with DMSO. The samples have been characterized by DSC, FTIR, and impedance spectroscopy. Based on the obtained results the speculations about the reasons for the presence of extremes in dependencies of both ion conductivity and activation energy on cation radius have been made. It is also suggested that solvate Li+(DMSO)4 is the minimum transport unit in Nafion-Li+ swollen in DMSO.
The lithium-ion conductivity of the lithium form of the commercial perfluorinated membrane Nafion-115 was studied in a series of aprotic solvents in a wide temperature range. The highest ion conductivity was obtained for the sample kept in N,N-dimethyl formamide (DMF); its use in lithium-ion batteries, however, is restricted by its low electrochemical stability. Mixed solvents based on dimethyl sulfoxide (DMSO) with propylene carbonate (PC) and 1,2-dimethoxyethane (DME) additions were optimum solvents for ion transport. The Nafion membrane in the lithium form kept in a mixed solvent DMSO: PC: DME = 1: 1: 2 was characterized by high ion conductivity at room temperature (2.0 mS/cm) and the absence of phase transitions in the temperature range from–40 to +60°C. The activation energy of conductivity of the samples kept in DMF, DMSO, and mixed solvents based on DMSO above the transition temperature was 15–20 kJ/mol.
Infrared and Raman spectra of dimethylsulfoxide and dimethylsulfoxide-d6 have been re-investigated. New assignments are proposed based on comparison of the spectra of various physical states and consideration of the polarisation of Raman lines. In the liquid state dimers and/or higher aggregates are present, but there is no evidence of autoassociation for concentrations less than 0,5 mole.l−1. The autoassociation constants calculated by earlier authors are incorrect as they are based on erroneous assignments.
The material's abundance is a simple and clear reason as to why sodium ions are attractive as charge carriers for rechargeable batteries. It is also expected that potassium ions have a further smaller desolvation energy compared with the Li and Na systems in aprotic solvents. However, further energy sacrifice is also unavoidable for the potassium system due to heavy atomic weight. In addition to the oxides, a wide variety of crystal structures is known for polyanionic compounds and the structural chemistry of the Na system is much more complicated in comparison to the Li system. Na ions are apparently coordinated by four fluoride ions at bottleneck sites when the Na ions migrate across the perovskite-type framework structure.
Solar radiation provides direct energy input to the earth's biosphere sustaining both biological and physical processes. Monumental industrial progress was ushered in by the discovery of technologies which enabled the recycling and repurposing of a portion of this energy by combustion of fossilized carbon matter derived from living tissues. Motive power represents an additional and a substantial opportunity for utilizing energy storage to minimize emissions of pollutants and greenhouse gases as well as substantially reduce fuel consumption. Toyota considers this a top priority and introduced the first-generation hybrid electric Prius in Japan in 1997. Currently, Toyota sells numerous hybrid models; consumer acceptance of this technology has resulted in global sales of 3.1 million hybrid electric vehicles (HEV).
Perfluorinated ionomer membranes either sulfonated or carboxylated have been extensively studied in order to understand the relations between their structure and properties. In addition to their uses as separator in the Cl2/NaOH industry large potential applications exist in different fields like sensors, batteries, fuel cells, electrochromic displays, etc. Some of these applications are due to the possibility of getting solutions, gels from these materials in different solvents and of reconstructing membranes of different thicknesses. The aim of this presentation is to present conductivity measurements of solutions, gels and bulk membranes, which measurements are of primary interest for potential applications in electrochemical devices. Room temperature measurements of conductivity of solutions/gels: First of all we recall the results already published which show the high conductivity of these gels associated with a transport number t+=1 since the COO− or SO3− anions are covalently bound to the rigid perfluorinated rod like structure. Low temperature measurements: Polymers having ionic conductivity usually show drastic changes upon temperature associated to transition (Tg, Tm or sub Tg relaxations). Measurements of conductivity of NAFION® 1100 solutions in propylene carbonate or dimethoxyethane over a temperature range between +20°C and −40°C have shown only small changes mainly due to viscosity modifications of the solvent as evidenced from the calculated activation energies. Conductivity/swelling measurements: We have recently developed an experiment which permits to obtain both the conductivity and the swelling of ion exchange membranes. Equilibrium experiments with solvent mixtures permit to check the conductivity and swelling changes versus different parameters (dielectric constant of solvent, ionic radius of the counterion, etc.). Diffusion coefficients are also obtained from the time lag when immersing the membrane in the solvent.
Polymer electrolytes are the basis for new types of practical power sources that free from the problems associated with the escape of corrosive, flammable, or toxic liquids. For successful lithium polymer batteries, a polymer electrolyte must have adequate ionic conductivity, together with high electronic conductivity, high cation mobility, good mechanical properties, the ability to form good interfacial contacts with electrodes, large electrochemical stability window, ease of processing, chemical and thermal stability, and safety. The most advanced polymer electrolytes for lithium polymer battery are formed by dissolving a lithium salt in a modified polyether.
Ionic conductivity and swelling data are measured for Nafion® perfluorinated ionomeric membranes in nonaqueous solvents and solvent mixtures and correlated with solvent physical properties. The dependence of ionic conductivity on solvent uptake and cation type is examined for Nafion® 117 membranes with a nominal equivalent weight of 1100 g/eq. The most important factors determining ionic conductivity in membranes swollen with polar nonaqueous solvents are the solvent viscosity, molar volume, donor properties, and the solvent uptake by the membrane. Ionic conductivity is generally limited by dissociation of the cation from the fixed anion site indicating that the ionomer fixed anion site basicity is the critical membrane property. Means for increasing membrane ionic conductivity are discussed.
A new proton-conducting polymer electrolyte polyethylene oxide (PEO)+(NH4)2SO4 has been reported. The proton transport in solution-cast films of PEO complexed with (NH4)2SO4 has been established using optical microscopy, XRD, DTA, IR, coulometry, transient ionic current and electrical conductivity studies. The highest electrical conductivity has been found to be 9.3× 10-7 S\cdotcm-1 for the NH4+/EO ratio equal to 0.0416. The transference number and mobility of protonic movement have been found to be tH+~=0.61 and muH+~=2.9× 10-7 cm2/volt-sec, respectively. The movement of anions (possibly HSO4-) also contribute to the overall conductivity.
With the aid of newly obtained Raman data, a normal coordinate analysis has been performed on the polytetrafluoroethylene (PTFE) molecule. Calculations were made for three different helix models including the 13/6, 15/7, and planar zigzag. The frequencies corresponding to the 15/7 helix were fitted by adjusting the force field. The conformation was changed, and the changes in the frequencies for the 13/6 helix and the planar zigzag were calculated using the same force field. Changes predicted for the 13/6 helix from the normal coordinate calculations are not in agreement with those actually observed at the 19°C transition. It was therefore hypothesized that the changes in the infrared and Raman spectra at this transition were due to Raman thermal defects as suggested by Brown. The potential-energy distribution was obtained for the optically active modes of the 15/7 helix, and the eigenvectors were presented for the motions of the A modes. The dispersion curve for the 15/7 helix is presented, and the coupling which occurs between the chain stretch and the CF stretching modes is discussed.
117 and 112 grades of H+ Nafion® membranes were studied using near-IR FT Raman scattering, IR absorption and ATR techniques. Tested membranes were as received, n water molecules per –HSO3 groups (n(117I)∼10, n(112I)∼2), equilibrated in water at RT (n(117II)∼20) or at 100°C (n(112II)∼16), air dried at 80°C (117III grade, n∼1) and 110°C (117IV grade, n∼3×10−1) and completely dried over P2O5 (117V). Infrared (ATR) and Raman spectra show that whatever the water uptake, Nafion® (117 and 112) skeleton retains the helical zigzag conformation of the polytetrafluoroethylene (PTFE) and that the (CF2CF2) links prevail on the fluorocarbon part of the side-pendant chains. Comparison with PTFE allows for the calculation of the crystallinity degree of Nafion® membranes.Two ν2 bending OH vibrations are observed at 1650 (water, acid water) and 1720 cm−1 (weakly-hydrated H3O+ ion). After drying, H3O+⋯SO3− interactions become visible and explain why the OH stretching massif shifts towards smaller wave numbers. At 80°C (117III), sub-maximum at 2980 cm−1 is assigned to H3O+ hydrogen bonded to SO3− groups. The acid water ν2 band disappears while the H3O+ band persists. In Nafion® 117IV, almost all the water content is eliminated and many sulfonic groups are undissociated. Formation of the hydrated cluster follows from the helical conformation of the (CF2)n backbone and from the relative position of adjacent chains.
The infra‐red spectra of thin non‐scattering films of NH4Cl and ND4Cl were obtained at 28°, −78° and −190°C. A convenient low temperature transmission type cell usable for such films is described. No indication of fine structure due to free rotation of the NH4+ ions was found. Instead, evidence is presented for the existence, both above and below the λ‐point, of a torsional lattice mode involving the NH4+ ions. The limiting frequencies of the torsional oscillations were observed at about 390 and 280 cm−1 for NH4Cl and ND4Cl, respectively. These values agree quite well with the frequencies calculated on the basis of a purely electrostatic potential function. The spectra of the low temperature modifications indicate strongly that the structures belong to the space group Td1 in which the NH4+ ion symmetry is Td. Of the eight observed bands, two are assigned to the triply degenerate fundamentals ν3 and ν4, one to the overtone 2ν4, one to the combination ν2+ν4 which resonates strongly with ν3, one to the combination of the totally symmetric mode, ν1, with the limiting lattice frequency, ν5, and two to the combinations involving the lattice torsional mode, ν6, i.e., ν4+ν6 and ν2+ν6. The spectra of the room temperature modifications are consistent with a structure in which the NH4+ ion tetrahedra are randomly distributed between the two possible equilibrium orientations in each unit cell. The λ‐point transformations are probably simple order‐disorder transitions between the two modifications.
The potential energy of polyethylene, polytetrafluoroethylene, polyoxymethylene, polyisobutylene, polyvinylidene chloride, and isotactic polypropylene with a helical conformation has been calculated as a function of the angles of rotation around the bonds of the backbone chain. The use of appropriate functions to describe the interaction between nonbonded atoms in the chains, has allowed prediction with surprising accuracy of the most stable conformation for the each polymer considered, in spite of the rather drastic assumptions involved in the calculations. The most prominent feature of the potential energy diagrams are discussed with reference to the possibility of predicting the allowed helical conformations for the isolated unperturbed polymer chains considered.
- H D Yoo
- I Shterenberg
- Y Gofer
- G Gershinsky
- N Pour
- D Aurbach
H.D. Yoo, I. Shterenberg, Y. Gofer, G. Gershinsky, N. Pour, D. Aurbach, Mg rechargeable batteries: an on-going challenge, Energy Environ. Sci. 6 (2013) 2265-2279.