Maximum Ionic Conductivity Value Research Articles

Nanocomposites composed of sulfonated polysulfone/hexagonal boron nitride/ionic liquid for supercapacitor applications

Abstract The present study investigates physicochemical properties of polymer electrolytes and their usage for construction of supercapacitor. The polymer electrolytes (SPE) comprising sulfonated polysulfone (SPSU) as host polymer, Ionic Liquid (1-Ethyl-3-methyl-imidazolium tetrafluoroborate (IL)) as softening agent, and Hexagonal boron nitride (hBN) as nano additive were mixed at various fractions. Different blend formulations were produced and characterized via spectroscopic techniques. The thermal properties of these materials were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Proton conductivity of the nanocomposite polymer electrolytes were analyzed within the temperature range from -20 °C to 100 °C. The maximum ionic conductivity values of the film containing SPSU/ 0.1 IL and SPSU / %5 hBN / 0.2 IL were measured as 2.5 × 10−4 and 1.3 × 10-3 S cm−1 at 100 °C, respectively. The produced membranes have promising dimensional stability, higher conductivity, and better thermal stability. A symmetrical cell of SPSU / %5 hBN/ 0.2 IL sample yielded a maximum specific capacitance of 90.4 F g-1 at 1 A g-1. The same electrolyte yielded a maximum energy density in supercapacitor as 43.8 Wh kg−1 at a power density of 1100 W kg-1.

Investigations on binary metal oxide based polyvinyl pyrrolidone/sodium nitrate polymer electrolytes for electrochemical cell applications

The flexible solid polymer electrolytes (SPE) based on polyvinylpyrrolidone (PVP):sodium nitrate (NaNO3) with binary metal oxide (BMO) have been prepared. The binary metal oxides (CuWO4 and BiVO4) are synthesized by using hydrothermal method and tested with X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The maximum ionic conductivity value of 1.018 × 10−4 S/cm (at 303 K) is obtained for PVP:NaNO3:BiVO4 system. The prepared electrolytes are ionic conductors which is proved by transport studies.The high conducting SPE can withstand upto 3.5 V from Linear Sweep Voltammetry studies (LSV) and it shows good cyclic behavior (CV studies). The open circuit voltage (OCV) of the electrochemical cell is observed to be 3.5 V.

Preparation of anion exchange membrane with branch polyethyleneimine as main skeleton component

A series of anion exchange membranes (AEMs) consisting of polyvinyl alcohol/branched polyethyleneimine (PVA/BPEI) were simply prepared by casting method using glutaraldehyde (GA) as crosslinking agent, then quaternized with benzyl chloride and alkalized in KOH solution. Subsequently, the comparative analysis was performed to select the optimal ratio of PVA to BPEI and crosslinking degree of AEMs. The structure and properties of AEMs were verified by FT-IR, XRD, TGA, mechanical analysis, water uptake test, swelling ratio test, ion exchange capacity (IEC) test, ionic conductivity measurement, and alkaline/oxidative stability test. The results showed that the maximum value of ionic conductivity was 86.0 mS/cm at 80 °C with IEC value of 2.35 meq/g. Moreover, the AEM had excellent chemical stability, as the ionic conductivity decreased by <15% in 1 M KOH at 80 °C for 7 days. These results indicated that polyethyleneimine is a promising raw material for the preparation of alkaline anion-exchange membranes used in fuel cell.

Design, synthesis and characterization of polysiloxane and polyetherdiamine based comb-shaped hybrid solid polymer electrolytes for applications in electrochemical devices

In this study, polysiloxane and polyetherdiamine based comb-shaped solid polymer electrolytes (SPEs) are developed by hydrosilylation and sol-gel reactions of polymethylhydrosiloxane, allyltriethoxysilane, bis(2-aminopropyl) polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol and (3-glycidoxypropyl)trimethoxysilane followed by LiClO4 doping. The absence of residual Si‒H functionality in FTIR and 29Si CPMAS NMR spectra confirms the completion of hydrosilylation reaction. The formation of comb-shaped SPEs with silicate backbones is confirmed by 13C and 29Si solid-state NMR spectroscopy. The maximum ionic conductivity value of 5.8 × 10−4 S cm−1 is obtained for the SPE with [O]/[Li] ratio of 16 at 80 °C with electrochemical stability window reaching up to 4.8 V. The fabricated electrochromic device with the hybrid SPE of [O]/[Li] = 16 demonstrates good electrochromic contrast and optical density change values of 49.3% and 0.39, respectively, at wavelength of 550 nm. The results show that the present comb-shaped SPEs have potential to be used in various electrochemical devices.

Low-viscosity ionic liquid–doped solid polymer electrolytes

Polymer electrolyte films based on poly(ethylene oxide) doped with salt sodium nitrate and ionic liquid (IL; 1-ethyl 3-methylimidazolium thiocyanate) have been prepared and characterized by differential scanning calorimetry (DSC) and impedance spectroscopy. The relative percentage of crystallinity of polymer electrolytes has been calculated by using DSC thermograms and electrical properties by using impedance spectroscopy. The incorporation of IL in polymer matrix increases the conductivity of polymer electrolyte. The maximum value of ionic conductivity of polymer electrolyte is found to be 1.93 × 10−4 S m−1 with 9 wt% IL.

Structural, electrical, and electrochemical properties of poly(vinylidene fluoride-co-hexaflouropropylene)/poly(vinyl acetate)-based polymer blend electrolytes for rechargeable magnesium ion batteries

An attempt has been made to prepare a new blend polymer electrolytes (BPEs) based on PVdF-co-HFP and PVAc doped with Mg (ClO4)2 by using the solvent-casting technique. The physicochemical properties of the as prepared polymer electrolytes were characterized by XRD, FTIR, SEM, TG/DTA, linear sweep voltammetry (LSV), and cyclic voltammetry (CV). The maximum ionic conductivity value 3.85 × 10−5 S cm−1 has been observed for PVdF-co-HFP (69)-PVAc (23)-Mg (ClO4)2 (8 wt%) system at 30 °C using AC impedance spectroscopic technique. The FTIR analysis confirms the complex formation between the polymers and salts. The TG/DTA studies showed the thermal stability of the film. The polymer electrolyte membrane shows a wide electrochemical stability window, and the temperature dependence of ionic conductivity obeys the Arrhenius rule.

Zinc oxide nanofiller-based composite polymer gel electrolyte for application in EDLCs

A ZnO nanofiller-based polymer gel electrolyte was prepared using solution-cast technique by incorporating PVDF-HFP as the polymer, ethylene carbonate (EC)-propylene carbonate (PC) as plasticizers, tetraethylammonium tetrafluoroborate (TEABF4) as salt, and ZnO as nanofiller. A maximum ionic conductivity value 6.3 × 10−3 Scm−1 was obtained by adding 12 wt% of ZnO nanoparticles in complex [{PVDF-HFP (20 wt%) + {EC-PC (v/v)-TEABF4 (1.0 M)} (80 wt%)}]. From the temperature-dependent conductivity plot, the activation energy is found to be equal to Ea ~ 0.07 eV. The amorphous structure is confirmed by SEM and XRD analysis. Electrochemical potential window and ionic transference number were calculated and found to be equal to ~3.3 V and 0.84, respectively. Optimized NCPGE is utilized in the fabrication of the electrical double-layer capacitor (EDLC) cell using market parched activated charcoal as electrode material. The specific capacitance of the fabricated EDLC cell is found to be equal to 162.9 mFcm−1 and ~ 67.8 Fg−1 for the single-electrode system.

A novel porous gel polymer electrolyte based on poly(acrylonitrile-polyhedral oligomeric silsesquioxane) with high performances for lithium-ion batteries

A novel porous membrane, based on a polymer matrix of poly(acrylonitrile-polyhedral oligomeric silsesquioxane) (P(AN-POSS)), is prepared by phase inversion process, and the corresponding gel polymer electrolyte (GPE) is further fabricated by immersing the porous membrane into liquid organic electrolyte. The thermal stability and structure of prepared POSS and polymers are investigated. The research indicates that the P(AN-POSS) membrane with copolymerization content of 8wt% POSS exhibits the better pore structure and superior electrolyte uptake compared with pure PAN membrane, which endows the corresponding GPE with remarkable comprehensive performances: the maximum ionic conductivity value of 6.06 × 10−3Scm−1 at ambient temperature, the sufficiently stable interface compatibility between GPE and electrode, the excellent lithium ion transference number of 0.59 and the higher electrochemical stability potential of 5.7V (vs. Li/Li+). At 0.2C, the GPE with 8wt% POSS in polymerization based lithium ion battery shows a satisfactory discharge capacity of 148mAhg−1 and improved capacity retention of 93.7% after 80 cycles.

Improved structural stability and ionic conductivity of Na3Zr2Si2PO12 solid electrolyte by rare earth metal substitutions

Sodium zirconium silicon phosphorus with the composition of Na3Zr2Si2PO12 (NZSP) was prepared by a facile solid state reaction method. The effects of the calcination temperature and rare earth element substitution on the structure and ionic conductivity of the NZSP material were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and AC impedance measurement. The results show that the microstructure and ionic inductivity of the NZSP was strongly affected by the aliovalent substitution of Zr4+ ions in NZSP with rare earth metal of La3+, Nd3+ and Y3+. At room temperature, the optimum bulk and total ionic conductivity of the pure NZSP solid electrolyte sintered under different conditions were 6.77×10−4 and 4.56×10−4Scm−1, respectively. Substitution of La3+, Nd3+ and Y3+ in place of Zr4+ exhibited higher bulk conductivity compared with that of pure NZSP. Maximum bulk and ionic conductivity value of 1.43×10−3 and 1.10×10−3Scm−1 at room temperature were obtained by Na3+xZr1.9La0.1Si2PO12 sample. The charge imbalance created by aliovalent substitution improves the mobility of Na+ ions in the lattice, which leads to increase in the conductivity. AC impedance results indicated that the total ionic conductivity strongly depends on the substitution element and the feature of the grain boundary.

Solid polymer electrolytes based on coupling of polyetheramine and organosilane for applications in electrochromic devices

In this work, cyanuric chloride is employed as the core element to react with polyetheramine in various ratios, and then chemical crosslinking with an organosilane, i.e., (3-isocyanatopropyl)triethoxysilane (ICPTES) to form a new organic-inorganic hybrid electrolyte with a core branched structure. The solid state of the hybrid electrolyte is fabricated via the doping of LiClO4 salt, and possessed the maximum ionic conductivity value of 1.1×10−4Scm−1 at 30°C and electrochemical stability window of around 5.0V for the sample with the [O]/[Li] ratio of 32. The structure of the organic-inorganic hybrid is confirmed by FTIR and solid-state NMR measurements. The lithium ion mobility in the hybrid electrolyte is investigated by monitoring the lithium linewidths from static 7Li solid-state NMR. An optical density change value of 0.56 and an exceptionally high coloration efficiency value of 675cm2C−1 with good cycle life are obtained when the present hybrid electrolyte is employed to fabricate the prototype electrochromic device. These electrochromic performances are the best as compared to the previously reported electrochromic devices made of hybrid electrolytes. The present organic-inorganic hybrid electrolyte holds great potentials to be used in different applications of electrochromic devices.

Investigation of Electrical Properties, Structure and Morphological Characterization of Mg+2 Ions Conducting Solid Polymer Electrolyte Based on Poly(vinyl alcohol)

In the present work, solid polymer electrolyte using poly(vinyl alcohol) (PVA) and magnesium perchlorate (Mg(ClO4)2) in different compositions has been prepared by the solution-casting technique method. Surface feature of films was characterized by scanning electron microscopy (SEM) measurement. X-ray diffraction (XRD) was used to determine the complexation of the polymer with the salt. The electrophysical characteristics were measured and analyzed as dependent on the concentration, nature of the solid polymer electrolyte component and ambient temperature. A maximum ionic conductivity value of ∼10–4 S/cm at 303 K is obtained for PVA0.6/(Mg(ClO4)2)0.4 composite. The ionic transference number of Mg+2 mobile ions has been estimated by a dc polarization method. The result reveals that the conducting species are predominantly ions.

Study of ionic conductivity of polytriazole and polynaphthalenediimide ion-exchange membranes

Transport properties of the new polytriazole and polynaphthalenediimide membrane materials have been observed. According to impedance data, the sulfonated polynaphthalenediimide membrane obtained in dimethylsulfoxide demonstrates the maximum value of ionic conductivity. Modification of a membrane material with silica leads to transport properties improvement.

Performance characteristics of guanine incorporated PVDF-HFP/PEO polymer blend electrolytes with binary iodide salts for dye-sensitized solar cells

In this work, we have investigated the influence of guanine as an organic dopant in dye-sensitized solar cell (DSSC) based on poly(vinylidinefluoride-co-hexafluoropropylene) (PVDF-HFP)/polyethylene oxide (PEO) polymer blend electrolyte along with binary iodide salts (potassium iodide (KI) and tetrabutylammonium iodide (TBAI)) and iodine (I2). The PVDF-HFP/KI + TBAI/I2, PVDF-HFP/PEO/KI + TBAI/I2 and guanine incorporated PVDF-HFP/PEO/KI + TBAI/I2 electrolytes were prepared by solution casting technique using DMF as solvent. The PVDF-HFP/KI + TBAI/I2 electrolyte showed an ionic conductivity value of 9.99 × 10−5 Scm−1, whereas, it was found to be increased to 4.53 × 10−5 Scm−1 when PEO was blended with PVDF-HFP/KI + TBAI/I2 electrolyte. However, a maximum ionic conductivity value of 3.67 × 10−4 Scm−1 was obtained for guanine incorporated PVDF-HFP/PEO/KI + TBAI/I2 blend electrolyte. The photovoltaic properties of all these polymer electrolytes in DSSCs were characterized. As a consequence, the power conversion efficiency of the guanine incorporated PVDF-HFP/PEO/KI + TBAI/I2 electrolyte based DSSC was significantly improved to 4.98% compared with PVDF-HFP/PEO/KI + TBAI/I2 electrolyte based DSSC (2.46%). These results revealed that the guanine can be an effective organic dopant to enhance the performance of DSSCs.

Preparation and characterization of biopolymer electrolyte based on cellulose acetate for potential applications in energy storage devices

In this present work, the solution casting technique was utilized to develop the proton conducting solid biopolymer electrolyte by the complex formation of cellulose acetate (CA) with the ammonium thiocyanate (NH4SCN) salt. The crystalline nature and complex formation of CA with different concentrations of NH4SCN were investigated using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopic techniques. The XRD analysis revealed that the amorphous natures of the CA complex were increased with increase of NH4SCN salt concentration, which leads to the higher ionic conductivity. The FTIR analysis confirmed the complex formation between CA and salt matrix. Differential scanning calorimetry (DSC) was used to predict the glass transition temperature (Tg) values, which reveals that the Tg value increase with respect to the increase of NH4SCN concentration. The electrical conductivity was measured using AC impedance analyzer, which showed that the magnitude of ionic conductivity increases with an increase in salt concentration up to 50CA:50NH4SCN. The 50CA:50NH4SCN has maximum ionic conductivity value of 3.31 × 10−3 S cm−1. Transference number measurement was carried out to investigate the nature of the charge transport species in the polymer electrolyte. The proton battery was constructed with the highest conducting polymer electrolyte 50CA:50NH4SCN and its open circuit voltage with load were studied. Hence, the present investigation paves the way for the development of fuel cell and primary proton battery applications.

Ionic conductivity of binary fluorides of potassium and rare earth elements

The ionic conductivity s of KYF4 and K2RF5 single crystals (R = Gd, Ho, Er) and KNdF4 and K2RF5 ceramic samples (R = Dy, Er) has been studied in the temperature range of 340–500°C. A comparative analysis of the σ values for these objects has been performed. Binary fluorides of potassium and rare earth elements were synthesized by the hydrothermal method (temperature 480°C, pressure 100–150 MPa) in the R2O3–KF–H2O systems. The σ values of tetraf luorides are 3 × 10–5 S/cm (KYF4 single crystal) and 3 × 10–6 S/cm (KNdF4 ceramics) at 435°C. A K2ErF5 single crystal with σ = 1.2 × 10–4 S/cm at 435°C has the maximum value of ionic conductivity among pentafluorides. The anisotropy of ionic transport was found in K2HoF5 single crystals, σ∥c/σ⊥c = 2.5, where σ∥c and σ⊥c are, respectively, the conductivities along the crystallographic c axis and in the perpendicular direction.

Blending of hard and soft organic–inorganic hybrids for use as an effective electrolyte membrane in lithium-ion batteries

In this study, two unique organic–inorganic hybrids are synthesized and optimized to obtain a new type of hybrid blend membrane. A soft hybrid is obtained from reaction of polyetheramine (M-2070) and (3-glycidyloxypropyl)trimethoxysilane (GLYMO), whereas a hard hybrid is prepared from reactions of polyetherdiamine (ED2003), poly(ethylene glycol) diglycidyl ether (PEGDGE) and GLYMO. Both hybrids are finally blended with poly(vinylidene fluoride-co-hexafluoropropylene) (P(VdF-HFP)) to get the hybrid blend membrane and plasticized with 1M LiPF6 in EC/DEC. The successful synthesis of the hybrid blend membrane structure is established from 13C and 29Si solid-state NMR spectroscopy. FTIR results reveal the interactions of different groups of the hybrid blend membrane. The hybrid blend electrolyte possesses maximum ionic conductivity value of 6.9mScm−1 at 30°C and is electrochemically stable up to 5V. The electrochemical performance of the hybrid blend electrolyte assemble in a battery cell with the LiFePO4 cathode exhibits a good cycle life of over 200 cycles with an initial discharge capacity of 150mAhg−1. In addition, coulombic efficiency of 97–99% is maintained for the whole cycles. Our results demonstrate that the present hybrid blend electrolyte can be a potential candidate serving as an effective electrolyte in lithium-ion batteries.

Preparation of hydrophilic polyethylene/methylcellulose blend microporous membranes for separator of lithium-ion batteries

Hydrophilic high density polyethylene/methylcellulose (HDPE/MC) blend microporous membranes were prepared via the thermally induced phase separation process. The effect of MC on the HDPE membranes was investigated by examining the morphology and determining the phase diagram, hydrophilicity, crystallinity, and mechanical properties. In addition, the electrochemical properties were evaluated from button cells consisting of the pure HDPE membrane and HDPE/MC blended microporous membranes as separators saturated by the LiPF6 electrolyte. The obtained results indicated that the cloud point temperature and the surface morphology of the membranes was shifted to high values and changed from dense to porous, respectively, with increasing MC content. The blended membranes also had a higher electrical uptake than the pure HDPE membrane. Moreover, the maximum ionic conductivity (1.01×10−3S/cm) and minimum activation energy (Ea) value (10.48kJ/mol) were obtained at an MC content of 2wt%. Furthermore, compared to those consisting of the pure HDPE membrane, button cells consisting of the HDPE/MC blend microporous membranes exhibited higher charge-discharge capacity and better discharge performance at various current densities.

The physical and electrochemical properties of poly(vinylidene chloride-co-acrylonitrile)-based polymer electrolytes prepared with different plasticizers

Lithium ion-conducting membranes with poly(ethylene oxide) (PEO)/poly(vinylidene chloride-co-acrylonitrile) (PVdC-co-AN)/lithium perchlorate (LiClO4) were prepared by solution casting method. Different plasticizers ethylene carbonate (EC), propylene carbonate (PC), gamma butyrolactone (gBL), diethyl carbonate (DEC), dimethyl carbonate (DMC), and dibutyl phthalate (DBP) were complexed with the fixed ratio of PEO/PVdC-co-AN/LiClO4. The preparation and physical and electrochemical properties of the gel polymer electrolytes have been briefly elucidated in this paper. The maximum ionic conductivity value computed from the ac impedance spectroscopy is found to be 3 × 10−4 S cm−1 for the EC-based system. From DBP-based system down to EC-based system, a decrease of crystallinity and an increase of amorphousity are depicted by X-ray diffraction technique, the decrease of band gap energy is picturized through UV–visible analysis, the decrease of glass transition temperature is perceived from differential scanning calorimetry plots, and the reduction of photoluminescence intensity is described through photoluminescence spectroscopy study at an excitation wavelength of 280 nm. Atomic force microscopic images of EC-based polymer electrolyte film show the escalation of micropores. Fourier transform infrared spectroscopy study supports the complex formation and the interaction between the polymers, salt, and plasticizer. The maximum thermal stability is obtained from thermogravimetry/differential thermal analysis, which is found to be 222 °C for the sample complexed with EC. The cyclic voltagram of the sample having a maximum ionic conductivity shows a small redox current at the anode, and cathode and the chemical stability is confirmed by linear sweep voltammetry.

Preparation and characterization of the porous solid polymer electrolyte of PAN/PVA by phase inversion

Porous solid polymer electrolytes (SPE) were prepared in the form of thin films by phase inversion by direct immersion in non-solvent acetone or methanol, using a copolymer of polyacrylonitrile and poly (vinyl acetate) in ethylene carbonate/dimethylene carbonate (EC/DMC 1:1 v/v) as plasticizer, which contained different LiClO4 percentages. SEM images revealed pores on a micrometer scale (average diameter around 2 μm) distributed inside and on the surface of the films. XRD patterns revealed a predominantly amorphous behavior, favorable to the ionic conduction process. Thin films presented low glass transition temperatures (T g), between −67 and −58 °C. Thin films showed a thermal stability higher than those obtained for the gels. Thin films (average thickness of 22 μm) showed ionic conductivity around 10−10 S cm−1 and 10−7 S cm−1 by immersion in acetone and methanol, respectively. The porous thin films when were swollen in liquid electrolyte, the maximum ionic conductivity value reached was of 2.5 × 10−4 S cm−1 with 10 % LiClO4 at 25 °C. The oxidation of the SPE only occurred around 4.5 V for the gel and 4.8 V versus Li/Li+ for the SPE thin film, thus resulting in a wide electrochemical stability. A stable passive layer at the interface between the polymer electrolyte and lithium metal was formed within the first 10 h and maintained during 4 weeks. The cell containing LiCoO2 in thin-film electrolyte presented the one well-known plateaux for the Li-ion intercalation in the 4 V region.

Effect of Al2O3 nanowires on the electrochemical properties of di-ureasil-based organic–inorganic hybrid electrolytes

Organic–inorganic hybrid electrolytes based on the reaction of triblock copolymer poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) bis(2-aminopropyl ether) and 3-(triethoxysilyl)propyl isocyanate doped with lithium trifluoromethanesulfonate and Al2O3 nanowires were synthesized by a sol–gel process. The structural and electrochemical properties of the materials thus obtained were systematically investigated by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry, thermogravimetric analysis, powder X-ray diffraction, 29Si CPMAS (cross-polarization magic angle spinning) NMR, alternate current impedance, and linear sweep voltammetry measurements. FTIR spectra showed the occurrence of complexation and interaction among the components. The maximum ionic conductivity values of 9.8 × 10−5 S cm−1 and 6.8 × 10−4 S cm−1 were obtained at 30 and 75 °C, respectively, for the solid hybrid electrolyte with a [O]/[Li] ratio of 16 and 1 wt% of Al2O3 nanowires. A Vogel–Tamman–Fulcher-like temperature dependence of ionic conductivity was observed for the hybrid electrolytes doped with fillers. The electrochemical stability window of ~4.0 V makes the organic–inorganic hybrid electrolyte promising for lithium-ion battery application at low voltages.