Polymer Electrolytes

PVA has been doped by different percentage of Lithium Iodide (LiI), electrical and optical properties of polymer electrolytes have been investigated. At low frequency, the variation of dielectric constant and dielectric loss with frequency shows the presence of material electrode inter-face polarization processes. The exponent factor found is between 0.98 and 0.442 and obeys the universal power law. The absorption of pure and doped films have been studied in the visible and ultra-violet wavelength regions. It has been observed that the new absorption peaks at 290 and 375 nm are due to the formation of charge transfer complex. From direct allowed transition the optical energy gap decreases from 5.56 eV (for pure PVA) to 4.95 eV (for PVA+20%LiI).

The physical and electrochemical properties of a new class of lithium ion conducting polymer electrolytes formed by incorporating MgAl 2 O 4 as filler into poly(ethylene oxide) − LiClO 4 complex are reported and discussed. The MgAl 2 O 4 -incorporated polymer electrolytes exhibited higher ionic conductivity and mechanical strength than those with filler-free membranes. These unique properties are accompanied by a good compatibility with lithium electrodes. The membranes were also subjected to scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetry (TG) and Fourier Transform-infrared (FT-IR) analyses. The lithium surface upon contact with polymeric membranes was analyzed by FT-IR by single internal reflection mode. Using the technique the formation of Li 3 MgAlO 4 on the lithium surface was identified.

The correlation between ionic conductivity and viscosity in liquid electrolytes formed by the dissolution of lithium tritlate in N,N-dimethyl formamide and tetraethylene glycol dimethyl ether has been investigated. These liquid electrolytes may be incorporated in polymer gel electrolytes based on poly(vinylidene fluoride). The use of the Walden product to investigate ionic interactions is discussed.

Potassium (K+) is the predominant intracellular
cation. It is essential to the function of all living cells.
Intracellular K+ concentration is over 30 times its
extracellular concentration. Serum K+ is dependent on
it s intake, excretion, and transcellular distribution.
Most of the body’s K+ is in the muscles. Aldosterone
is the main regulator of K+ renal excretion.
Hypokalemia (serum K+ < 3.5 mEq/l) has multiple
manifestations affecting different organ systems.
Careful history and basic laboratory tests are usually
adequate to diagnose most cases of hypokalemia. K+
should be replaced orally whenever feasible.
Intravenous K+ replacement is needed for emergency
management of hypokalemia and in patients who
cannot take oral potassium.

Ionic liquids (ILs) and deep eutectic solvents (DESs) have been applied in various fields such as electrolytes for lithium ion batteries, electrodeposition, electropolishing and even in fuel cells. ILs and molten salts have found some applications in redox flow batteries (RFBs) in the past and recently some metal ion based ILs have been proposed and used by Sandia National Laboratories. In addition, only two papers have very recently reported on the application of DESs for the same. This review gives an overview on DESs and discusses the possibility of employing them in RFBs for renewable energy storage and utility-scale load leveling applications. Commencing with a discussion on energy storage technologies and the RFB, this paper goes on to provide an account on ILs and DESs as well as their applications in electrochemistry and energy conversion. A succinct discussion on the results of Sandia National Laboratories on using ILs as electrolytes for RFBs is provided building onto the feasibility of replacing ILs with DESs in the near future (based upon recent publications on the topic).

The purpose of this manuscript is to analyze the effect of temperature and exchange
current density on operating cell voltage, resistance and ionic conductivity of the polymer
electrolyte. Equations related to mathematical models for PEM Electrolyzer based on a combination
of thermodynamics fundamental and electrochemical relations of the well-known Butler-Volmer
kinetic have been used to simulate the system. The result of this study shows a significant drop in
membrane Ohmic resistance as the temperature decreases. In conclusion the best operation
temperature that corresponds to lower voltage (1.82 V) is 80oC. At power density of about 9 W/
cm2, hydrogen flow rate of 3.5ml/min and 3.78 was observed at 40oC and 80oC respectively, this
account for only about 7% increase hydrogen flow rate. These model results are found to agree well
with previous published work.

Highly conductive anion exchange membranes (AEMs) are one of the few requirements to produce high power during fuel cell operation and for efficient hydrogen production through water electrolysis. The use of chemically stable and cheap AEMs with platinum group metal (PGM)-free catalysts is suitable for reducing the overall cost of hydrogen production and fuel cell operation. The in situ durability of anion exchange membrane fuel cells (AEMFCs) and anion exchange membrane water electrolyzers (AEMWEs) for several hundred hours is necessary for the widespread application of fuel cell and water electrolysis technologies. This Minireview highlights the best results reported recently in alkaline membrane fuel cells and water electrolysis. The achievable AEMFCs performances are noteworthy using Pt-free anode and cathode electrocatalysts. Remarkable durability in AEMFCs is witnessed, although the durability is a concern for AEMWEs. Moreover, the current challenges and future directions of AEMFCs and AEMWEs are briefly summarized.

Ionic liquids (ILs) and deep eutectic solvents (DESs) have been applied in various fields such as electrolytes for lithium ion batteries, electrodeposition, electropolishing and even in fuel cells. ILs and molten salts have found some applications in redox flow batteries (RFBs) in the past and recently some metal ion based ILs have been proposed and used by Sandia National Laboratories. In addition, only two papers have very recently reported on the application of DESs for the same. This review gives an overview on DESs and discusses the possibility of employing them in RFBs for renewable energy storage and utility-scale load leveling applications. Commencing with a discussion on energy storage technologies and the RFB, this paper goes on to provide an account on ILs and DESs as well as their applications in electrochemistry and energy conversion. A succinct discussion on the results of Sandia National Laboratories on using ILs as electrolytes for RFBs is provided building onto the feasibility of replacing ILs with DESs in the near future (based upon recent publications on the topic).

The effect of carbon black and ceramic (a-Al 2 O 3 and g-Al 2 O 3 ) particles on the cationic and polymer chain mobility have been investigated in poly(ethylene oxide)-lithium salt (LiClO 4 and LiBF 4 ) solid composite polymer electrolytes by using nuclear magnetic resonance (NMR) techniques. Proton ( 1 H) and lithium ( 7 Li) lineshapes and spin-lattice relaxation times were measured as a function of temperature. The 7 Li data indicates that the lineshape and relaxation is affected by the coupling of its quadrupolar moment to the surrounding electric field gradients. Activation energies extracted from the 7 Li relaxation data are in the range 0.20-0.25 eV. Results show that the addition of a-Al 2 O 3 influenced both, the relative cation mobility and the polymer chain motion. Calculation shows that this result is in quantitative agreement with the conductivity data.

h i g h l i g h t s < New concept in rechargeable aqueous batteries. < Deposition/dissolution anode and intercalation cathode in aqueous electrolyte. < Energy storage system with large capacity retention and long cycle life. < Alternative to commercial lead-acid batteries and for load leveling applications.

Increasing Polymer Electrolyte Fuel Cells' (PEFCs) operating temperature has benefits on the performance and the ease of utilisation of the heat generated; however, efforts for high temperature PEFCs have resulted in high degradation and reduced life time. In the literature , conventional low temperature (T < 80 C) and high temperature (140e200 C) regimes have been extensively studied, while the gap of operating at intermediate temperature (IT) (100e120 C) has been scarcely explored. The main bottleneck for operating at IT conditions is the development of a suitable proton exchange membrane with comparable performance and lifetime to the commercially used Nafion operating at conventional conditions. In this work, composite membranes of Graphene Oxide (GO) and Nafion of varied thickness were fabricated, characterised and assessed for in-situ single cell performance under automotive operating conditions at conventional and intermediate temperatures. The material characterisation confirmed that a composite GO-Nafion structure was achieved. The composite membrane demonstrated higher mechanical strength, enhanced water uptake, and higher performance. It was demonstrated that by utilising GO-Nafion composite membranes, an up to 20% increase in the maximum power density at all operating temperatures can be achieved, with the optimum performance is obtained at 100 C. Moreover, the GO-Nafion membrane was able to maintain its open circuit voltage values at increased temperature and reduced thickness, indicating better durability and potentially higher lifetime.

Polymers are a class of materials widely used in different fields of applications. With imminent applications of polymers, the study of radiation induced changes in polymers has become an obvious scientific demand. The bombardment by ion beam radiations has become one of the most promising techniques in present day polymer research. When the polymers are irradiated, a variety of physical and chemical changes takes place due to energy deposition of the radiation in the polymer matrix. Scissoring, cross-linking, recombination, radical decomposition, etc. are some of the interesting changes that are obvious in polymers. The modification in polymer properties by
irradiation depends mainly on the nature of radiation and the type of polymer used. Polymer electrolytes are obtained by modifying polymers by doping, complexing, or other chemical processes. In general, they suffer from low conductivity due to high crystallinity of the matrix. The
effect of radiation on polymer electrolyte is expected to alter their crystalline nature vis-a-vis electrical properties. This review article shall elaborate modifications in the physical and chemical properties of polymer electrolytes and their composites. The variations in properties have been explored on PEO based polymer electrolyte and correlated with the parameters responsible for such changes. Also a comparison with different types of the polymers irradiated with a wide range of ion
beams has been established.

The ion dynamics and relaxation behavior of a novel polymer electrolyte system
is studied by presenting impedance spectroscopy data in a different formalism.
The prepared system has conductivity of the order of 10
−3
Scm
−1
at 303 K, and
the RH % = 55. Depressed Nyquist plots and broadenedM˝curves (as a function
ofω) indicated the distribution of the relaxation time, which is further confirmed
by the fractional value of the Kohlrausch–William–Watts (KWW) function
(β∼0.75). The hopping and caged movement of the ions are observed in the
experimental frequency range (∼MHz), which is confirmed by the conductivity
and dielectric representations. The scaling of the conductivity data, with reference to salt concentration and temperature, are successfully observed byfitting
the conductivity data exclusively in the Jonscher Power Law (JPL) region. An
inverse relation between τcon andσindicated a strong correlation between the
ion and polymer segment motion. An additional high frequency relaxation
phenomenon is observed at 50% of the salt concentration, which is correlated
with the self-diffusion of the ion and proposed that such phenomenon is
observed when ions have multiplet forming tendency

Dye sensitized solar cells (DSSCs) were fabricated using anthocyanin dye and polymer electrolyte with ammonium iodide (NH4I) salt. The study was designed to focus on increasing the efficiency of the DSSC. DSSC using 26.9 wt.% chitosan-22wt.% NH4I(+2.2 wt.% I-2)-48.9wt. % IL solid electrolyte, black rice anthocyanin with Pt counter electrode showed J(sc) of 172 mu A cm(-2) and V-oc of 195mV. The performance of the cell with Pt electrode was further improved by coating a blocking layer on the indium tin oxide (ITO) substrate. The black rice DSSC using 11wt. % (chitosan:PEO, wt. ratio 30: 70)-9wt. % NH4I-80wt. % BMII gel electrolyte exhibited J(sc) of 1213 mu A cm(-2), V-oc of 400mV, FF of 0.47, and eta of 0.23%. The red cabbage anthocyanin DSSC containing (phthaloyl chitosan-PEO)-NH4I-BMII gel electrolyte using tartaric acid to adjust the pH of anthocyanin solution showed the best performance with the fill factor of 0.39, J(sc) of 3503 mu A cm(-2), V-oc of 340mV, and an overall conversion efficiency of 0.46%.

Soggy sand" electrolyte, which essentially consists of oxide dispersions in nonaqueous liquid salt solutions, comprises an important class of soft matter electrolytes. The ion transport mechanism of soggy sand electrolyte is complex. The configuration of particles in the liquid solution has been observed to depend in a nontrivial manner on various parameters related to the oxide (concentration, size, surface chemistry) and solvent (dielectric constant, viscosity) as well as time. The state of the particles in solution not only affects ionic conductivity but also effectively the mechanical and electrochemical properties of the solid−liquid composite. Apart from comprehensive understanding of the underlying phenomena that govern ion transport, which will benefit design of better electrolytes, the problem has far-reaching implications in diverse fields such as catalysis, colloid chemistry, and biotechnology.

Water electrolysis using an anion conductive, solid polymer electrolyte is an attractive method for point-of-use hydrogen
production. Recent advances in catalysts and anion exchange membranes (AEM) have made alkaline devices increasingly
competitive with their acidic counterparts. However, less attention has been paid to the anion conductive ionomers (ACI) used in
the fabrication of electrodes for AEM electrolyzers. The ACI contributes to ion conduction between the catalyst and bulk
electrolyte and serves as a binder for adhering the catalyst to the gas diffusion layer and AEM. Ionic conductivity, water uptake and
ionomer swelling are critical properties for electrode performance. High ion exchange capacity (IEC) in the ionomer is desired for
reduced electrode resistance, however, it can lead to excess water uptake (WU) and disruptive ACI swelling. In this study, a series
of poly(norbornene)-based ionomers were synthesized, characterized and used to fabricate oxygen evolving anodes for lowtemperature
AEM water electrolysis. The IEC of the ionomers (0 to 4.73 meq g−1) was adjusted by controlling the ratio of ion
conducting to non-ion conducting norbornene monomers in the ACI tetrablock copolymers. Low conductivity ionomers are shown
to yield the best-performing oxygen evolution electrodes, in the absence of ACI polymer cross-linking because they do not
experience excessive water swelling. Light cross-linking within the anode ACI was used as a means to independently lower WU of
the ionomer without compromising ionic conductivity. This control over water swelling allows higher ionic conductivity within the
ACI to be used in water-fed electrolyzer applications. Other methods of water management were compared including the use of
hydrophobic additives and adjustment of the ionomer concentration in the electrode. It was shown that the cell performance greatly
benefits from a highly conductive ionomer in the oxygen evolution reaction electrode if the WU is managed.

The ionic conductivity of a block copolymer electrolyte was measured in an in situ small-angle X-ray scattering experiment as it transitioned from an ordered lamellar structure to a disordered phase. The ionic conductivity increases discontinuously as the electrolyte transitions from order to disorder. A simple framework for quantifying the magnitude of the discontinuity is presented. This study lays the groundwork for understanding the effect of more complex phase transitions such as order−order transitions on ion transport.

Self-organized Titanium dioxide (TiO2) nanotubes grown on Ti grid acting as anode for Li-ion microbatteries were prepared via an electrochemical anodization. By tuning the anodization time, the morphology and length of the nanotubes were investigated by scanning electron microscope. When the anodization time reached 1.5 h, the TiO2 nts/Ti grid anode showed a well-defined nanotubes, which are stable, well-adherent ∼90 nm with a length of 1.9 ± 0.1 µm. Due to their high surface utilization, surface area, and material loading per unit area, TiO2 nts/Ti grid anode using polymer electrolyte exhibited a high areal capacity of 376 µAh cm −2 at C/10 rate and a stable discharge plateau at 1.8 V without using a polymer binder and conductive additive. The storage capacity of the TiO2nts/Ti grid after 10 cycles is 15 times higher compared to previous reports using planar Ti foils.

Graphene (GN) has many beneficial properties that encourage wide applications. Various manufacturing procedures are detailed in the literature but most are unable to produce GN flakes in bulk and usually result in toxic discharges. These techniques are also time-consuming and involve operations at high temperatures. A 'greener', simpler and a one-step synthesis of the material may be realised by electrochemical oxidation (or reduction) of the graphite host leading to intercalation of ions from the electrolyte (which may be aqueous, organic or an ionic liquid) followed by electrochemical exfoliation. Single- or multi-layered GN flakes can easily be produced in short periods of time, typically within 30 min. This paper reviews the state-of-the-art methods reported in the literature regarding electrochemical synthesis of GN flakes as well as their properties (determined via sophisticated analytical methods such as AFM, TEM, SEM or Raman spectroscopy). This is followed by a discussion on the applications of electrochemically prepared GN flakes. Challenges and opportunities are briefly considered leading to the conclusion that the cathodic intercalation of lithium ions into graphite can produce the highest yield (>70%) of pristine GN flakes in organic electrolytes. Future work is recommended with ternary eutectic melts as electrolytes. © 2012 Elsevier Ltd. All rights reserved.

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Liquid electrolytes composed of lithium salt in a mixture of organic solvents have been widely used for lithium-ion batteries. However, the high flammability of the organic solvents can lead to thermal runaway and explosions if the system is accidentally subjected to a short circuit or experiences local overheating. In this work, a cross-linked composite gel polymer electrolyte was prepared and applied to lithium-ion polymer cells as a safer and more reliable electrolyte. Mesoporous SiO 2 nanoparticles containing reactive methacrylate groups as cross-linking sites were synthesized and dispersed into the fibrous polyacrylonitrile membrane. They directly reacted with gel electrolyte precursors containing tri(ethylene glycol) diacrylate, resulting in the formation of a cross-linked composite gel polymer electrolyte with high ionic conductivity and favorable interfacial characteristics. The mesoporous SiO 2 particles also served as HF scavengers to reduce the HF content in the electrolyte at high temperature. As a result, the cycling performance of the lithium-ion polymer cells with cross-linked composite gel polymer electrolytes employing methacrylate-functionalized mesoporous SiO 2 nanoparticles was remarkably improved at elevated temperatures. The rapidly expanding use of rechargeable lithium-ion batteries as power sources for portable electronic devices, electric vehicles and energy storage systems has led to intensive research on electrolyte systems with high elec-trochemical performance 1–8. The liquid electrolyte used in lithium-ion batteries is based on lithium salt dissolved in a mixture of organic carbonate solvents. It provides high conductivity, acceptable electrochemical stability and good cycle performance. However, current lithium-ion batteries have risks associated with leakage and fire hazards due to the high flammability of the organic solvents 9–11. In addition, the polyolefin separators used in lithium-ion batteries may shrink and even melt at elevated temperatures, which may cause a short circuit between the two electrodes in cases where unusually high heat is generated 12–14. Therefore, there is a pressing need for safer and more reliable electrolyte systems. Among various electrolyte systems, gel polymer electrolytes have received considerable attention due to their high ionic conductivity, good interfacial adhesion to electrodes and effective encapsulation of organic solvents in the cell, resulting in suppression of solvent leakage and enhanced safety 15–17. However, the incorporation of liquid electrolyte into the polymer matrix to improve the ionic conductivity deteriorated the mechanical strength of the polymer electrolyte, leading to internal shorts and battery failure. The mechanical strength of the gel polymer electrolytes was enhanced by in-situ chemical cross-linking or addition of inorganic fillers such as SiO 2 , Al 2 O 3 , TiO 2 and BaTiO 3 18–26. In the in-situ thermal cross-linking process, gel electrolyte precursors containing liquid electrolyte and cross-linking agents were injected directly into the cell, and a cross-linked gel polymer electrolyte was formed by free radical polymerization triggered by thermal initiation 27–29. The cross-linked polymer networks that were swelled with the liquid electrolyte showed high ionic conductivity, favorable interfacial properties and good mechanical strength. In our previous studies, we synthesized cross-linked composite polymer electrolytes using reactive SiO 2 particles with C= C double bonds 30 .

Polymer electrolytes are electrolytes that consist of polymer/salt complex and contain free ions which render them electrically conductive. They are used extensively in applications such as batteries, capacitors, and photovoltaic cells. In this study, a series of 4-cyano-4'-pentylbiphenyl (5CB) nematic liquid crystal-doped polyvinyl alcohol (PVA) polymer electrolytes were prepared and the effects of the concentration of the doped 5CB on the properties of the electrolytes were characterized by alternating current (AC) impedance spectroscopy. The increase in conductivity which was achieved through the doping of 5CB suggests that the embedded liquid crystal (LC) molecules increased the ordering strength in the electrolyte, which provides a better pathway to transfer generated charges inside the polymer electrolyte. Characterization of the polymer electrolyte liquid crystal system (PeLCs) by electrochemical and spectroscopic techniques reveals the influence of LC in the PeLC optical and electrochemical band gaps. (C) 2015 Elsevier Ltd. All rights reserved.

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Ionic liquid-based proton conducting polymer electrolytes containing poly(vinyl alcohol) (PVA), ammoniumac-
etate (CH3COONH4) and 1-butyl-3-methylimidazoliumbromide (BmImBr) are prepared and investigated in this
present work. The ionic conductivity of polymer electrolytes increases with temperature as shown in tempera-
ture dependent-ionic conductivity study. All the polymer electrolytes follow Vogel–Tamman–Fulcher (VTF)
relationship. This principle infers the coupling effect of ionic hopping mechanism and free volume theory. The
pseudo-activation energy of all the polymer electrolytes is also determined by fitting the plotswith VTF empirical
equation. The complexation between PVA, CH3COONH4 and BmImBr is verified in Attenuated Total Reflectance–
Fourier TransformInfrared (ATR–FTIR) study. Addition of ionic liquid reduces the crystallinity of polymer electro-
lytes as proven in x-ray diffraction (XRD) by calculating the degree of crystallinity of polymer electrolytes.
The crystallite sizes of polymer electrolytes are also determined using XRD. Proton nuclear magnetic resonance
(H-NMR) spectrum reveals the rapid conduction mechanism in the polymer electrolyte by determining the ion
diffusion coefficient.

Ion-containing block copolymers are of interest for applications such as electrolytes in rechargeable lithium batteries. The addition of salt to these materials is necessary to make them conductive; however, even small amounts of salt can have significant effects on the phase behavior of these materials and consequently on their ion-transport and mechanical properties. As a result, the effect of salt addition on block copolymer thermodynamics has been the subject of significant interest over the past decade. This feature article describes a comprehensive study of the thermodynamics of block copolymer/salt mixtures over a wide range of molecular weights, compositions, salt concentrations, and temperatures. The Flory−Huggins interaction parameter was determined by fitting small angle X-ray scattering data of disordered systems to predictions based on the random phase approximation. Experiments on neat block copolymers revealed that the Flory−Huggins parameter is a strong function of chain length. Experiments on block copolymer/salt mixtures revealed a highly nonlinear dependence of the Flory−Huggins parameter on salt concentration. These findings are a significant departure from previous results and indicate the need for improved theories for describing thermodynamic interactions in neat and salt-containing block copolymers.

As solid oxide fuel cells (SOFCs) are highly nonlinear systems, a single linear controller cannot perform satisfactorily over a wide range of operating conditions of the processes. This work studies multilinear-model predictive control of a tubular SOFC. The objective is to control the fuel cell outlet voltage over a wide range of operating conditions by manipulating inlet fuel pressure (flow rate). A first-principles model of an ammonia fed-tubular solid oxide fuel cell is used for the controller design. The model accounts for diffusion, inherent impedance, transport (momentum, heat and mass transfer), electrochemical reactions, activation and concentration polarizations, and the ammonia decomposition reaction. The servo and regulatory performances of the multimodel predictive controller (MMPC) are compared with those of a single-model predictive controller (SMPC) and a proportional-integral (PI) controller. For small load changes, the MMPC, SMPC, and PI controller all provide zero offset, and the MMPC yields the best closed-loop performance. However, for large load changes, the SMPC and PI controller fail to provide zero offset; under these two controllers the closed-loop system with the large load changes is unstable.

http://pubs.acs.org/doi/pdfplus/10.1021/ie301107r

Polymer-coated Carbon Nanotube (CNT) tissues are very flexible and lightweight and have high potential as an anode material for flexible Li-ion microbatteries. The electrochemical deposition of p-sulfonated poly(allyl phenyl ether) (SPAPE) polymer electrolyte into CNT tissues has been accomplished using a cyclic voltammetry (CV) technique. When compared to a pristine CNT tissue, the capacity of SPAPE-coated CNT tissue after 10 cycles of CV is improved about 67% at 1C rate. The enhancement of electrochemical performance is obtained when the CNT tissues are coated with the SPAPE polymer electrolyte. The higher capacity of the SPAPE-coated CNT tissue is attributed to the increased surface area and the improved quality of the electrode/electrolyte interfaces between the nanotubes and the polymer electrolyte. The SPAPE-coated CNT tissue delivers a higher reversible capacity of 750 mAh g−1 (276 µAh cm−2) compared to a pristine CNT tissue, which solely provides a reversible capacity of 450 mAh g−1 (166 µAh cm−2) after 110 cycles at 1C rate. Remarkably, the SPAPE-coated CNT tissue reaches a high capacity up to 12C rate while observing that the capacity can be significantly recovered.

The ionic conductivity and glass transition temperatures of
nanostructured block copolymer electrolytes composed of polystyrene-b-poly(ethylene oxide) (SEO) doped with lithium bis-(trifluoromethanesulfone)imide (LiTFSI) were studied in the small molecular weight limit (between 2.7 and 13.7 kg mol−1). In this range, the annealed conductivity exhibits a nonmonotonic dependence on molecular weight, decreasing with increasing molecular weight in the small molecular
weight limit before increasing when molecular weight exceeds about 10 kg mol−1. We show that annealed electrolyte conductivity is affected by two competing factors: the glass transition temperature of the insulating polystyrene (PS) block and the width of the conducting poly(ethylene oxide) (PEO) channel. In the low molecular weight limit, all ions are in contact with both PS and PEO segments. The intermixing between PS and PEO segments is restricted to an interfacial zone of width, λ. Our experiments suggest that λ is about 5 nm. The fraction of ions affected by the interfacial zone decreases as the conducting channel width increases. We also study the effect of thermal history on the conductivity of the block copolymer electrolytes. Our data suggest that long-range order impedes ion transport.

Solid polymer electrolyte films based on hydroxypropyl methylcellulose (HPMC) with different concentrations of cadmium chloride (CdCl 2 ) were prepared by solution cast method. Different techniques has been employed to investigate the effects of structural, thermal and ionic conductivity behavior of these polymer electrolyte films upon gamma irradiation with different doses of 20, 60 and 100 kGy. The dissolution of the salt into the polymer host and the structural properties of pure and CdCl 2 (1% -4%) (wt. %) complexed HPMC polymer electrolyte films before and after irradiation was confirmed by Xray diffraction (XRD) studies. XRD results revealed that the amorphous domains of HPMC polymer matrix was increased with increase in the salt concentration and with the gamma dose. The percentage of crystallinity is found to be high in pristine unirradiated HPMC films. The thermal properties of these polymer electrolyte films before and after irradiation were studied using differential scanning calorimetry (DSC). The results revealed that the presence of CdCl 2 in the polymer matrix increases the melting temperature, however it is observed that the total enthalpy of fusion ( ) is maximum for unirradiated pristine HPMC films. The variation of film morphology was examined by scanning electron microscopy (SEM). Direct current (dc) conductivity was measured in the temperature range of 313-383K. The magnitude of conductivity was found to increase with increasing concentration of the salt, temperature and for higher dose of radiation. The composition HPMC:CdCl 2 (5:4) for unirradiated and irradiated samples, found to exhibit the least crystallanity and the highest conductivity.

Natural growth of diffusion-limited aggregate (DLA), without any external stimuli, in boric acid doped starch system is reported here. Fractals grown were confirmed to be of diffusion-limited aggregate (DLA) pattern having fractal dimension∼1.49. Effect of substrate and humidity on growth pattern has also been discussed. The existence of a different vibration band of H3BO3 in FTIR confirmed that growth structures are related to boric acid. XRD pattern has shown broad peak along with some sharp peaks. Broad peak is related to starch’s amorphous nature, as where intense sharp peaks are due to boric acid.

In this paper we present a computer simulation study of ionic conductivity in solid polymeric electrolytes. The multiphase nature of the material is taken into account. The polymer is represented by a regular lattice whose sites represent either crystalline or amorphous regions with the charge carrier performing a random walk. Different waiting times are assigned to sites corresponding to the different phases. A random walk (RW) is used to calculate the conductivity through the Nernst-Einstein relation. Our walk algorithm takes into account the reorganisation of the different phases over time scales comparable to time scales for the conduction process. This is a characteristic feature of the polymer network. The qualitative nature of the variation of conductivity with salt concentration agrees with the experimental values for PEO-NH 4 I and PEO-NH 4 SCN.

We report the electrodeposition of polymer electrolyte (PMMA-PEG) in porous lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O 4) cathode layer by cyclic voltammetry. The cathode-electrolyte interface of the polymer-coated LNMO electrode has been characterized by scanning electron microscopy and electrochemical techniques. Electrochemical measurements consisting of galvanostatic cycling tests and electrochemical impedance spectroscopy revealed a significant improvement of the capacity values and the increase of the operating voltage. These effects are attributed to the total filling of pores by the electrodeposited polymer that contributes to improve the reversible insertion of Li +. A complete all-solid-state microbattery consisting of electropolymerized LNMO as the cathode, a thin polymer layer as the electrolyte, and TiO 2 nanotubes as the anode has been successfully fabricated and tested.

In this review article, the recent progress in poly (ethylene oxide) based polymer electrolytes are comparatively studied based on the characterization of the poly(ethylene oxide) for its application in energy storage devices. Requirements for the polymer host, salt, solvent, nanofiller, and ionic liquid are elaborated in detail followed by the comparison of polymer electrolytes obtained by complexation of silver trifluoromethane sulfonate [AgCF 3 SO 3 ] (also known as silver triflate) with PEO and PEO blend of Lithium trifluoromethanesulfonate with linear formula CF 3 SO 3 Li based on influence of addition of additives to improve electrical conductivity and crystallinity of the PEO matrix.

Perfluoroimide acid (PFIA) belongs to a new class of Multi Acid Side Chain (MASC) poly-electrolyte membranes. Classical molecular dynamics simulations were carried out to study the hydrated nanostructure of PFIA and transport of water molecules and hydronium ions at T = 300 K and T = 353 K for a range of hydration levels. The radial distribution functions showed negligible change with temperature. The PFIA chain radius of gyration was minimally influenced by hydration and temperature which makes it suitable for fuel cells. Our simulations showed the formation of a large continuous water phase cluster in PFIA at high hydration levels which has also been observed in conductive probe atomic force microscopy experiments. These large continuous clusters lead to significantly higher vehicular diffusion rates for water molecules and hydronium ions at higher hydration levels. The vehicular diffusivity constants for water molecules and hydronium ions for PFIA were comparable to those for Nafion at both T ¼ 300 K and T ¼ 353 K. The vehicular proton conductivity values for PFIA were observed to be higher than those for Nafion at both T ¼ 300 K and T ¼ 353 K which agrees qualitatively with the experimental trends. Introduction Fuel cells are seen as a promising source of energy especially in the transportation sector. Hydrogen is an energy-dense fuel [1] which helps in increasing the range of fuel cell powered vehicles. Large-scale energy storage is necessary for energy produced from sustainable but intermittent sources of energy like wind and solar. These sources will, in turn, promote a hydrogen based economy because of the low cost of producing energy needed to generate hydrogen by techniques like water splitting [2e4]. For a hydrogen based economy, energy storage solutions play a key role. Flow batteries [5] are one of the solutions proposed for energy storage.

A conducting polymer system, having room temperature conductivity~1.26 × 10 −4 S/cm (for 50% NaI concentration) and ionic transference number~0.80, has been prepared by mixing NaI in a novel polymer host (synthesized polymer + poly (ethylene oxide)). Mobility (μ) and total number of charge carriers (N), estimated from dielectric parameters, have a value of~1.65 × 10 −2 cm 2 V −1 s −1 and 4.70 × 10 16 cm −3 respectively. Inverse relationship between conductivity power law exponent n and N/N 0 (fractional number of dissociated charge carriers) is explained in terms of statistical nature of ion dynamics. The temperature dependence of "n" studied separately in universal power law (UPL) and super linear power law (SLPL) region revealed that exponent n responds differently to temperature in these two different regions. Ion hopping frequency (ω p ), obtained from universal power law (UPL) region, is used for scaling of conductivity and permittivity curves. Conductivity scaling followed a master curve Y = 1 + X n , having n = 0.85 ± 0.07, covering both UPL as well as SLPL region which confirms that both phenomena have the same origin.

Potassium (K+) is the predominant intracellular cation. It is essential to the function of all living cells. Intracellular K+ concentration is over 30 times its extracellular concentration. Serum K+ is dependent on it s intake, excretion, and transcellular distribution. Most of the body’s K+ is in the muscles. Aldosterone is the main regulator of K+ renal excretion. Hypokalemia (serum K+ &lt; 3.5 mEq/l) has multiple manifestations affecting different organ systems. Careful history and basic laboratory tests are usually adequate to diagnose most cases of hypokalemia. K+ should be replaced orally whenever feasible. Intravenous K+ replacement is needed for emergency management of hypokalemia and in patients who cannot take oral potassium.

The effect of carbon black and ceramic (a-Al 2 O 3 and g-Al 2 O 3) particles on the cationic and polymer chain mobility have been investigated in poly(ethylene oxide)-lithium salt (LiClO 4 and LiBF 4) solid composite polymer electrolytes by using nuclear magnetic resonance (NMR) techniques. Proton (1 H) and lithium (7 Li) lineshapes and spin-lattice relaxation times were measured as a function of temperature. The 7 Li data indicates that the lineshape and relaxation is affected by the coupling of its quadrupolar moment to the surrounding electric field gradients. Activation energies extracted from the 7 Li relaxation data are in the range 0.20-0.25 eV. Results show that the addition of a-Al 2 O 3 influenced both, the relative cation mobility and the polymer chain motion. Calculation shows that this result is in quantitative agreement with the conductivity data.

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The electrolyte is a critical component of dye-sensitised solar cells (DSSCs). Among them, quasi-solid state (QSS) electrolytes are considered as one of the most prospective substitutes for liquid electrolytes to DSSCs. To entirely understand and optimise the performance and stability of QSS, comprehensive characterisation is needed to design new materials, comprehend and optimise the QSS. This review summarises the characterisations of QSS beginning from 2010. Emphasis is placed on the physical characterisations such as viscosity, morphology, thermal, infrared spectroscopy, nuclear magnetic resonance, Raman, ultraviolet-visible, and X-ray diffraction. All parts of the characterisation process are divided into the introduction, the objective of testing, main outcomes and finally, the selected examples. A summary of recent and important measurements on QSS are mentioned at the end.

Solid biopolymer electrolyte based on methylcellulose (MC) were prepared with different weight percentage of ammonium triflate (NH4TF) salt via solution casting technique. The film was characterized by impedance spectroscopy to measure its ionic conductivity. Samples with 45% of NH4TF exhibit the highest conductivity of 1.14 x 10-4 S cm-1 at ambient. Dielectric data were analysed using complex permittivity and complex electrical modulus for the sample with highest conductivity. Dielectric data proved that the increase in conductivity is mainly due to the increase in number of charge carriers.

Interest in the exfoliation of graphite to prepare few layer graphene (FLG) has seen significant growth. The electrochemical procedure has, unfortunately, remained rather elusive to scaling-up options. This work builds on recent results of employing acetonitrile (ACN) as a solvent for reducing the amount of expensive ionic liquids (ILs) used as electrolytes. In order to move towards a more environmentally friendly synthesis route, the yield and energy consumption of graphene exfoliation using the four main types of deep eutectic solvents (DESs) has been investigated. Best performance, in terms of the highest specific yield (graphene weight per unit energy consumed) of 0307 g/kJ, is observed when Type IV DES is employed as the electrolyte in ACN. Similar results, but with less specific yield, is observed when Type I DES is used (other DESs and the IL, BMPyrrBTA, did not provide high yields of graphene but produced more carbonaceous particles and rolled sheets instead). The physicochemical properties of the DESs also confirm that the best DES for exfoliation is the Type IV variant, which needs further investigation. The quality of graphene produced is excellent (4-5 layers, 80% transparency, specific surface area of 180 m(2)/g, conductivity of 2.1 x 10(5) S/m and a contact angle of 94 degrees thereby displaying hydrophobicity) and comparable to most graphene produced via other means. While maintaining high quality, the application of ACN and DES is economically attractive compared to other methods. (C) 2015 Elsevier B.V. All rights reserved.

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