Poly(ethyleneglycol methacrylate phosphate) and heterocycle based proton conducting composite materials

Novel anhydrous proton conducting polymer electrolytes based on poly(ethyleneglycol methacrylate phosphate) (PEGMAP) and heterocycle have been investigated. The materials were synthesized via conventional radical bulk polymerization of ethylene glycol methacrylate phosphate in the presence of proton solvents such as imidazole (Im) or benzimidazole (BnIm). The poly(EGMAP–Im_x) or poly(EGMAP–BnIm_x) composites were produced where x is the molar ratio of heterocycle to monomer in the feed. The polymer–heterocycle electrolytes were characterized by elemental analysis (EA), FT-IR spectroscopy, thermogravimetry analysis (TG), differential scanning calorimetry (DSC) and impedance spectroscopy. Maximum proton conductivity of 2 × 10^− 4 S/cm has been obtained for the anhydrous composite electrolytes at 160 °C.     

Proton conductivity and microstructures of the core-shell type solid electrolytes in the MO2-In2O3-P2O5 (MTi,Sn, Zr) systems

The proton conducting 0.9MO₂·0.05In₂O₃·1.3P₂O₅ (MTi, Sn, Zr) electrolytes based on a core-shell structure were synthesized by a ball milling method. The core-shell type electrolytes showed the proton conductivities ranging from a higher value than those of Nafion membranes to 10^? 5 Scm^? 1 at intermediate temperatures of 150–200 °C, depending on the heat-treatment conditions. The samples with high conductivity were proved to adopt a core-shell structure by SEM observation, powder XRD analysis and ³¹P MAS-NMR measurements.     

Electrical characterization of nano-composite polymer gel electrolytes containing NH4BF4 and SiO2: role of donor number of solvent and fumed silica

Nano-composite polymer gel electrolytes were synthesized by using polyethylene oxide (PEO), ammonium tetrafluoroborate (NH₄BF₄), fumed silica (SiO₂), dimethylacetamide (DMA), ethylene carbonate (EC), and propylene carbonate (PC) and characterized by conductivity studies. The effect of donor number of solvent on ionic conductivity of polymer gel electrolytes has been studied. The mechanical strength of the gel electrolytes has been increased with the addition of nano-sized fumed silica along with an enhancement in conductivity. Maximum room temperature ionic conductivity of 2.63 × 10⁻³ and 2.92 × 10⁻³ S/cm has been observed for nano-composite gel electrolytes containing 0.1 and 0.5 wt% SiO₂ in DMA+1 M NH₄BF₄+10 wt% PEO, respectively. Nano-composite polymer gel electrolytes having DMA have been found to be thermally and electrically stable over 0 to 90 °C temperature range. Also, the change in conductivity with the passage of time is very small, which may be desirable to make applicable for various smart devices.

     

PEG crosslinked poly(vinylbenzene boronic acid) polymer electrolytes for Li-ion batteries

Poly(4-vinylbenzeneboronic acid), PVBBA was synthesized via free-radical polymerization of 4-vinylbenzeneboronic acid (4-VBBA) and followed by crosslinking with polyethylene glycol (PEG) with different molecular weights to produce boron containing crosslinked polymers. Prior to crosslinking, the materials were doped with CF₃SO₃Li at several stoichiometric ratios to get PVBBAPEGX-Y where X is the molecular weight of PEG and Y is the EO/Li ratio. The materials were characterized by using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). The ionic conductivity of these novel crosslinked electrolytes was studied by dielectric-impedance spectroscopy. Li-ion conductivity of these polymer electrolytes depends on the length of the side units as well as the doping ratio. PVBBAPEG200-10 illustrated a satisfactory ionic conductivity of 3.1 × 10^?5 S/cm at 20 °C and 1.8 × 10^?3 S/cm at 100 °C.     

Development of proton conducting biopolymer membrane based on agar–agar for fuel cell

A proton-conducting polymer electrolyte based on agar and ammonium nitrate (NH₄NO₃) has been prepared through solution casting technique. The prepared polymer electrolytes were characterized by impedance spectroscopy, X-ray diffraction, and Fourier transform infra-red spectroscopy. Impedance analysis shows that sample with 60 wt.% NH₄NO₃ has the highest ionic conductivity of 6.57 × 10⁻⁴ S cm⁻¹ at room temperature. As a function of temperature, the ionic conductivity exhibits an Arrhenius behaviour increasing from 6.57 × 10⁻⁴ S cm⁻¹ at room temperature to 1.09 × 10⁻³ S cm⁻¹ at 70 °C. Transport parameters of the samples were calculated using Wagner’s polarization method and thus shows that the increase in conductivity is due to the increase in the number of mobile ions. Fuel cell has been constructed with the highest proton conductivity polymer 40agar/60NH₄NO₃ and the open circuit voltage is found to be 558 mV.

     

Structural and electrical properties of pure and H<Subscript>2</Subscript>SO<Subscript>4</Subscript> doped (PVA)<Subscript>0.7</Subscript>(NaI)<Subscript>0.3</Subscript> solid polymer electrolyte

Solid polymer electrolytes (SPE) based on poly-(vinyl alcohol) (PVA)_0.7 and sodium iodide (NaI)_0.3 complexed with sulfuric acid (SA) at different concentrations were prepared using solution casting technique. The structural properties of these electrolyte films were examined by X-ray diffraction (XRD) studies. The XRD data revealed that sulfuric acid disrupt the semi-crystalline nature of (PVA)_0.7(NaI)_0.3 and convert it into an amorphous phase. The proton conductivity and impedance of the electrolyte were studied with changing sulfuric acid concentration from 0 to 5.1 mol/liter (M). The highest conductivity of (PVA)_0.7(NaI)_0.3 matrix at room temperature was 10⁻⁵ S cm⁻¹ and this increased to 10⁻³ S cm⁻¹ with doping by 5.1 M sulfuric acid. The electrical conductivity (σ) and dielectric permittivity (ε′) of the solid polymer electrolyte in frequency range (500 Hz–1 MHz) and temperature range (300–400) K were carried out. The electrolyte with the highest electrical conductivity was used in the fabrication of a sodium battery with the configuration Na/SPE/MnO₂. The fabricated cells give open circuit voltage of 3.34 V and have an internal resistance of 4.5 kΩ.     

Proton-conducting properties of the membranes based on poly(vinyl phosphonic acid) grafted poly(glycidyl methacrylate)

Proton-conducting properties of the graft copolymer electrolytes were examined throughout this work. The homopolymers poly(glycidyl methacrylate), PGMA and poly(vinyl phosphonic acid), PVPA were synthesized by free-radical polymerizations of the monomers glycidyl methacrylate, GMA, and vinyl phosphonic acid, VPA, respectively. The graft copolymers were produced by grafting of PVPA onto PGMA via ring opening of ethylene oxide groups. To examine the influence of the concentration of VPA on the proton conductivity, several graft copolymers were produced at various stoichiometric ratios with respect to monomer repeat units. The materials were characterized by FT-IR and ¹H NMR spectroscopy and the thermal properties were studied by thermogravimetry (TG) and differential scanning calorimetry (DSC). The TGA results demonstrated that the samples are thermally stable up to at least 150 °C. The proton conductivities of humidified and dry samples were studied via impedance spectroscopy. In the anhydrous state, the proton conductivity of P(GMA)-graft-P(VPA)₁₀ was 5 × 10^? 5 S/cm at 150 °C. The proton conductivity of the same material increased with the humidity content and reached to 0.03 S/cm at 80 °C under 50% of RH, which approached to that of Nafion^® at the same humidification level.     

A study on ac and dc conductivity characteristics of Y-doped BaCeO3 modified by Ar+ ion beam

The effects of surface modification on electrical characteristics in bulk, grain boundary and interface (electrolyte/electrode) of BaCe_0.9Y_0.1O_3-δ were investigated. The surface modification was performed by means of two processes: specimen was firstly irradiated by 10 keV Ar⁺ ion with dose of 1 × 10¹⁸ ions/cm² and then exposed to air. The modified surface was investigated by elastic recoil detection analysis (ERDA) for quantitative analysis of hydrogen concentration on the surface and alternating current (AC) and direct current (DC) conductivity measurements, respectively. The ERDA results showed that hydrogen concentration and reaction rate on the modified surface increased. The increase of hydrogen concentration was explained in terms of the increase of proton due to interaction between oxygen vacancy formed by modification and H₂O. In AC and DC electrical conductivity measurements, it concluded that the proton and electronic carrier generated on the surface by modification attributed to the increase of bulk, grain boundary and interface conductivity.     

New type of inorganic–organic hybrid (heteropolytungsticacid–polyepichlorohydrin) polymer electrolyte with TiO2 nanofiller for solid state dye sensitized solar cells

A new type of inorganic–organic hybrid solid state polymer electrolyte consisting of heteropolytungsticacid impregnated polyepichlorohydrin with iodine/iodide and TiO₂ nanofiller have been prepared for their potential application in dye sensitized solar cells. The prepared polymer electrolytes were well characterized by FT-IR, Scanning electron microscopy (SEM), X-ray diffraction (XRD), Electrochemical Impedance analysis (EIS) and Thermal analysis (TGA). The prepared polymer electrolyte with TiO₂ nanofiller shows reasonable ionic conductivity (20.4 × 10⁻⁶ S cm⁻¹) compared to pure polyepichlorohydrin (2.0 × 10⁻⁹ S cm⁻¹) at ambient temperature. The presence of negatively charged redox species heteropolytungsticacid in the polymer matrix prevents the photo reduction of iodide (back electron transfer) and the presence of TiO₂ nanofiller increases the degree of amorphousity of the polymer which in turn prolongs the stability of the fabricated dye sensitized solar cell over a long period compared to bare polymer electrolyte.     

Synthesis of oligomeric poly[(1, 2-propanediamine)-alt-(oxalic acid)] and anomalous proton conductivities of the thin films

New proton-conductive polyamide oligomers, oligomeric poly[(1, 2-propanediamine)-alt-(oxalic acid)], were synthesized to investigate the proton transport properties of bulk and thin films. The obtained oligomers were characterized by the X-ray diffraction, FT-IR spectra, ¹H NMR, Matrix Assisted Laser Desorption/Ionization Time of Flight (MALDI-TOF) mass spectrum, and electrical conductivity measurements. The bulk proton conductivity is 3.0 × 10^? 4 S cm^? 1 at the relative humidity (RH) of 80%. The proton conductivity of thin film is relatively higher than that of bulk sample. Thickness dependence of the proton conductivity was observed in these thin films. The maximum proton conductivity of the thin film is 4.0 × 10^? 3 S cm^? 1 at the relative humidity (RH) of 80%, which is higher one order magnitude than that of the bulk sample. The activation energies of bulk and 200 nm thick film are 1.0 and 0.69 eV at the RH of 60%, respectively.     

Characterization of hybrid organic and inorganic functionalised membranes for proton conduction

Titanium zirconium phosphate and organic polymer hybrid (poly-vinyl alcohol, (3-glycidoxypropyl)-trimethoxysilane and ethylene glycol) based membranes were investigated for their potential application as proton conductors. The hybrid materials were characterized by XRD, FTIR, SEM, TGA and impedance spectroscopy analysis. It was found that embedding of functionalised inorganic particles (TiZrP) into composite polymer matrix allowed for some crystallinity formation, and cross-linking of hydroxyl groups during annealing or reactions within the organic and inorganic phases during synthesis. A complex structure was formed, as many FTIR peaks were masked by more defined peaks assigned to P–O–R bonds. The high concentration of phosphorus in the TiZrP (1:1:9 molar ratio) samples resulted in more hydrophilic particles. This was further reflected in the hybrid membranes as the water losses increased from 13 to 25 wt.% as a function of the TiZrP content changing from 10 to 50 wt.% in the final hybrid membrane, respectively. As a result, proton conductivity increased by two to three orders of magnitude from blank (organic phase only) membranes (2.61 × 10^− 5 S cm^− 1) to TiZrP hybrid membrane (2.41 × 10^− 2 S cm^− 1) at 20 °C. Proton conduction changed as a function of temperature and the Ti1Zr1P9 particles content, mainly attributed to the membrane ability to retain water, thus complying with the Grotthus mechanism.     

An investigation of the proton conductivities of hydrated poly(vinyl alcohol)/boric acid complex electrolytes

Proton-conducting polymer complex electrolytes were prepared by incorporation of boric acid, H₃BO₃ into poly(vinylalcohol), PVA, to form hydrated PVAxH₃BO₃ where x denotes the number of moles of boric acid per polymer repeat unit. The dried materials were characterized via Fourier transform infrared spectroscopy, thermogravimetry, and X-ray diffraction. The proton conductivity of the hydrated complex electrolytes was measured by AC impedance spectroscopy. PVA2H₃BO₃ with RH ∼25% was found to be optimum composition that exhibited proton conductivity of 1.3 × 10⁻³ S/cm at 80 °C.     

Characterization of hybrid electrolytes prepared from the Li2S-P2S5 glasses and alkanediols

Inorganic-organic hybrid electrolytes were prepared by the mechanochemical method using the Li⁺ ion conductive 70Li₂S·30P₂S₅ glass and various alkanediols. Local structure of the prepared electrolytes was analyzed by FT-IR and Raman spectroscopy. The effects of the proportion and chain length of alkanediols on conductivity of the hybrid electrolytes were investigated. The hybrid electrolyte with 2 mol.% of 1,4-butanediol exhibited the conductivity of 9.7 × 10^− 5 S cm^− 1 at room temperature and the unity of lithium ion transference number. The use of alkanediols with shorter chain length was effective in increasing conductivity of hybrid electrolytes. The electrolyte using ethyleneglycol showed the highest conductivity of 1.1 × 10^− 4 S cm^− 1 at room temperature. Lowering glass transition temperature by incorporation of alkanediols is responsible for the enhancement of conductivity of hybrid electrolytes.     

Effect of dibutyl phthalate as plasticizer on high-molecular weight poly(vinyl chloride)–lithium tetraborate-based solid polymer electrolytes

A series of different composition of polymer electrolytes-based on poly(vinyl chloride) (PVC) as host polymer, lithium tetraborate (Li₂B₄O₇) as dopant salt, and dibutyl phthalate (DBP) as plasticizer were prepared by solution casting method. The interaction between the PVC, Li₂B₄O₇, and DBP were studied by Fourier transform infrared. The shifting, broadening, and splitting of transmission peaks were the evidences of complexation. The highest ionic conductivity polymer electrolyte of 2.83 × 10⁻⁶ S/cm was achieved at ambient temperature upon addition of 30 wt.% of DBP. In addition, the temperature-dependent conductivity, frequency-dependent conductivity, dielectric permittivity, and modulus studies were performed. The temperature-dependent conductivity of the polymer electrolytes was found to obey the Arrhenius behavior. The thermal stability of polymer electrolytes was verified by thermogravimetric analysis. The lower in glass transition temperature was proven in differential scanning calorimetry, whereas the higher amorphous region within the polymer matrix was demonstrated in X-ray diffraction.     

Investigation of dibutyl phthalate as plasticizer on poly(methyl methacrylate)–lithium tetraborate based polymer electrolytes

Polymer electrolyte membranes, comprising of poly(methyl methacrylate) (PMMA), lithium tetraborate (Li₂B₄O₇) as salt and dibutyl phthalate (DBP) as plasticizer were prepared using a solution casting method. The incorporation of DBP enhanced the ionic conductivity of the polymer electrolyte. The polymer electrolyte containing 70 wt.% of poly(methyl methacrylate)–lithium tetraborate and 30 wt.% of DBP presents the highest ionic conductivity of 1.58 × 10⁻⁷ S/cm. The temperature dependence of ionic conductivity study showed that these polymer electrolytes obey Vogel–Tamman–Fulcher (VTF) type behaviour. Thermogravimetric analysis (TGA) was employed to analyse the thermal stability of the polymer electrolytes. Fourier transform infrared (FTIR) studies confirmed the complexation between poly(methyl methacrylate), lithium tetraborate and DBP.     

Poly-acrylonitrile-based gel-polymer electrolytes for sodium-ion batteries

Research and development activities on sodium-ion batteries are becoming prominent in the past few years. Compared to lithium-based batteries, the sodium-based batteries will be cheaper because of the abundancy of sodium raw materials in the earth’s crust and also in seawater. In the current study, we synthesized and characterized poly-acrylonitrile (PAN)-based gel-polymer electrolytes formed with NaClO₄ and dissolved in ethylene carbonate (EC) and propylene carbonate (PC). By systematically varying the weight ratios of polymer, salt, and the solvents, we obtained an optimum room temperature ionic conductivity of 4.5 mS cm⁻¹ for the composition 11PAN-12NaClO₄-40EC-37PC (wt.%), which is reasonably good for practical applications. This value of conductivity is comparable to a few other Na⁺ ion conducting gel-polymer electrolyte systems studied in the recent past. Variation of ionic conductivity with inverse temperature showed Arrhenius behavior. Activation energies estimated for all the samples showed only a slight variation suggesting that a single activation process which depends on the EC/PC co-solvent governs the ionic mobility in these gel-polymer electrolytes. Thermo-gravimetric analysis (TGA) revealed that there is no noticeable weight loss of these electrolytes up to 100 °C and hence the electrolytes are thermally stable for operating temperatures up to 100 °C.

     

Synthesis and characterization of proton-conducting polymer electrolyte based on polyacrylonitrile (PAN)

Solid polymer electrolytes based on polyacrylonitrile (PAN) doped with ammonium iodide (NH₄I) have been prepared by solution casting method with different molar ratios of polymer and salt using DMF as solvent. The XRD pattern confirms the dissociation of salt. The FTIR analysis confirms the complex formation between the polymer and the salt. A shift in glass transition temperature (T _g ) of the PAN/NH₄I electrolytes has been observed from the DSC thermograms, which indicates the interaction between the polymer and the salt. The conductivity analysis shows that the polymer electrolyte with 20 mol% NH₄I has the highest conductivity equal to 1.106 × 10⁻³ S cm⁻¹ at room temperature. The activation energy (E _a ) has been found to be low for the highest conductivity sample. The dielectric permittivity (ε*) and modulus (M*) have been calculated from the alternating current (AC) impedance spectroscopy in the frequency range 42 Hz–1 MHz. The DC polarization measurement shows that the conductivity is mainly due to ions.

     

Preparation and characterization of solid polymer electrolytes based on PHEMO and PVDF-HFP

Polymer electrolyte membranes consisting of a novel hyperbranched polyether PHEMO (poly(3-{2-[2-(2-hydroxyethoxy) ethoxy] ethoxy}methyl-3′-methyloxetane)), PVDF-HFP (poly(vinylidene fluoride-hexafluoropropylene)) and LiTFSI have been prepared by solution casting technique. X-ray diffraction of the PHEMO/PVDF-HFP polymer matrix and pure PVDF-HFP revealed the difference in crystallinity between them. The effect of different amounts of PVDF-HFP and lithium salts on the conductivity of the polymer electrolytes was studied. The ionic conductivity of the prepared polymer electrolytes can reach 1.64 × 10^? 4 S·cm^? 1 at 30 °C and 1.75 × 10^? 3 S·cm^? 1 at 80 °C. Thermogravimetric analysis informed that the PHEMO/PVDF-HFP matrix exhibited good thermal stability with a decomposition temperature higher than 400 °C. The electrochemical experiments showed that the electrochemical window of the polymer electrolyte was around 4.2 V vs. Li⁺/Li. The PHEMO/PVDF-HFP polymer electrolyte, which has good electrochemical stability and thermal stability, could be a promising solid polymer electrolyte for polymer lithium ion batteries.     

A conductivity study of polyelectrolytes based on 4-vinyl pyridine and butylmethacrylate

Abstract  In this paper, the chain flexibility of P4-VP was tried to increase by lowering its glass transition temperature (T _g) and by increasing its amorphous region by copolymerizing with butyl methacrylate. The copolymers were prepared in five different feed molar ratios to optimize the required properties such as higher room temperature conductivity and film-forming capacity. The conductivity and conduction behavior of the copolymers, as well as their hydrochloride and hydrobromide salts, have been reported. The copolymers were prepared by solution polymerization technique, using tetrahydrofuran as solvent at 60 °C, and the salts were prepared by simple acidification. The copolymers and their salts were characterized by scanning electron micrographs, infrared, proton nuclear magnetic resonance, thermogravimetric, differential scanning calorimetry and AC impedance measurements. There was about 10³- to 10⁴-fold increase in room temperature conductivity of these plasticized polyelectrolytes. The conduction behavior was found to be predominantly ionic. The scientific importance of this paper is that, unlike polymer electrolytes, no external salt is used; instead the virgin polymer and polyelectrolytes are used for conductivity measurements.     

Investigations on electrical properties of poly(vinyl alcohol) doped with 1-methyl-3-n-decyl-imidazolium bromide ionic liquid

Thin films of poly(vinyl alcohol) (PVA) that are 100–500 μm thick were prepared by solution casting method. Various ratios of 1-methyl-3-n-decyl-imidazolium bromide ionic liquid [MDIM]⁽⁺⁾Br^(?), were used as dopants (plasticizers) to control the conductivity of the PVA thin films. Fourier transform infrared spectroscopy (FTIR) was used to indicate the detailed interaction of PVA with proton of the dopant in the blends. Ac impedance spectroscopy was used to investigate the impedance of the films within a frequency range of 10–10⁶ Hz as a function of temperature between 298 and 425 K. Each film with a precise doping concentration was sandwiched between two stainless–steel electrodes. The results showed that the electrical conductivity can be engineered by controlling the [MDIM]⁽⁺⁾Br^(?) doping concentration. Therefore, those films have potential to be used in flexible and cheap organic device applications.