Nanocomposite Polymer Electrolytes Research Articles

Synthesis and assessment of novel Na2S dispersed high performance nanocomposite gel polymer electrolyte intended for sodium batteries and electric double layer capacitors

Sodium sulphide (Na2S) nanoparticles are synthesized by hydrothermal method and utilized for electrochemical application for the first time. A series of sodium-ion conducting nanocomposite gel polymer electrolytes (NCGPEs) incorporating poly (methyl methacrylate) i.e., (PMMA) as the polymer backbone, sodium tetrafluoro-borate (NaBF4) as the salt, tetraethylene glycol dimethyl ether (TEGDME) as the plasticizer, and Na2S as the active fillers, are fabricated and studied. The optimized electrolyte having PMMA/NaBF4/TEGDME matrix incorporated with 2.5 wt% Na2S nanoparticles exhibits a high ionic conductivity of 3.0 × 10−4 S cm−1, low activation energy of 0.13 eV and operating voltage range of ~2.8 V at ambient temperature. Thermal studies reveal that the fabricated NCGPEs have the ability to retain the gel phase up to 473 K. The X-ray diffraction (XRD) and Fourier transform Infra-red (FTIR) spectroscopy indicate changes in structure and the ion–filler–polymer interactions inside the synthesized NCGPEs. A proto-type sodium cell with an optimized NCGPE has an open circuit voltage of 2.3 V and a first discharge capacity of 205 mAh g−1. The electric double layer capacitor (EDLC) designed with optimized electrolyte has a specific capacitance of 58 F g−1 and is stable up to 2000 charge-discharge cycles.

Studies of the Properties of New Electrospun Based on PVA-PEG Polymer Systems Electrolytes for Energy Storage Devices

Solid polymer electrolytes (SPEs) have been considerably investigated due to various electrochemical device applications. Most of the SPEs comprise polymer as a host material to provide strength and good mechanical stability and salt that transfers charge carriers to cause conductivity. Nanocomposite solid polymer electrolyte membranes based on poly(vinyl alcohol) (PVA)-poly(ethylene glycol) (PEG) blend complexed with LiClO4 and nanofillers Al2O3 at different weight percent ratios have been obtained by using electrospinning method. The conductivity and structural properties of the different systems have been characterized by using various experimental approaches such as X-ray diffraction (XRD) and Fourier transform infrared FTIR spectroscopy. The ionic conductivity of the systems has been measured by using an LCR meter in a temperature ranging from 298 to 353 K. Maximum ionic conductivity of 1.58 × 10-4 S cm-1 at room temperature has been observed for the system of PVA-PEG-LiClO4-Al2O3 (50-25-15-10) with 15 wt% weight percent of LiClO4 salt in PVA-PEG blend matrix. The ac conductivity report indicates that the ionic conductivity of the PVA-PEG-LiClO4-Al2O3 complex is influenced by the concentration of LiClO4. The effect of temperature on the ionic conductivity of polymer electrolyte complexes has been estimated by changing the temperature ranging from 298 to 353 K. However, the conductivity of the nanofiber polymer electrolyte systems increases with the rise of temperature, and the maximum conductivity of 1.58 × 10-2 S cm-1 has been recorded at 353 K. The temperature-dependent conductivity follows the Arrhenius behavior.

To Study the Effect of Nanoparticle TiO2 on Sodium (Na+) – Ion Conducting Solid Polymer Electrolyte System: [80PEO:20NaPF6

AbstractTo study the effect of nanofiller particle TiO2 on sodium (Na+) – ion conducting solid polymer electrolyte (SPE) film: [80PEO:20NaPF6] and nanocomposite polymer electrolyte (NCPE): [80PEO:20NaPF6] + xTiO2, where x = 1–9 wt. (%) have been prepared. SPE film composition: [80PEO:20NaPF6] selects as Ist‐phase host and nano‐sized (<100 nm) filler materials TiO2 as IInd‐phase dispersoid. Both SPE and NCPE films have been prepared by the hot‐press technique. Filler particle‐dependent conductivity study reveals the NCPE system: [80PEO:20NaPF6] + 8TiO2 as the highest conducting composition with σrt − 3.53 × 10−6 S cm−1, which is approximately one order of magnitude higher than the SPE optimum conducting composition (OCC) (σrt) ≈ 7.78 × 10−7 S cm−1. Ion transport properties for both SPE and NCPE system have been evaluated in terms of ionic conductivity (σ) and total ionic (tion)/cationic (t+) transference numbers using combined AC/DC techniques in order to evaluate its usefulness in all‐solid‐state battery applications. Structural/thermal properties have been characterized using X‐ray diffraction (XRD) and differential scanning calorimetry (DSC) techniques. A cyclic voltammetry (CV) study has been performed in SPE and NCPE OCC film to evaluate the electrochemical performance for battery application.

Solid polymer nanocomposite electrolytes based on poly(ε‐caprolactone)‐based waterborne polyurethane–polyethylene oxide and fluorine‐doped carbon quantum dot‐MXene

AbstractThe need for higher energy storage capability has encouraged researchers to move toward lithium‐metal batteries (LMBs). Due to the safety issue associated with liquid electrolytes, solid polymer electrolytes (SPEs) the main focus on polyethylene oxide (PEO) were at the center of the research. However, high crystallization, fast decomposition, and low thermomechanical stability has limited its application. Low lithium‐ion transference number () is another issue leading to polarization of the SPEs and consequently, triggering dendrite nucleation and growth. Here, we developed a series of SPEs based on PEO‐waterborne polyurethane (WPU) and nanoparticles of fluorine‐doped carbon quantum dot (fCQD) and MXene. The host polymer matrix was a blend of poly(ε‐caprolactone) (PCL)‐based WPU and PEO. The use of WPU and the nanoparticles increased the thermomechanical stability and suppressed PEO crystallinity through disrupting the spherulites growth and reducing the thermal stability of the crystallites. Using the WPU led to significant increase in () compared with previous reports. The prepared SPEs showed high‐electrochemical stability and ionic conductivity at and based on the results of cycling performance, a discharge capacity of 120.58 mAh/g and coulombic efficiency of 99.1% was achieved after 200 cycles.

A comprehensive study on structural, optical, electrical, and dielectric properties of PVA-PVP/Ag-TiO2 nanocomposites for dielectric capacitor applications

Nanocomposites made from polymers and nanoparticles (NPs) have a wide range of uses. Herein, the polymer nanocomposite electrolyte films were prepared by blending polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) with hybrid NPs of silver (Ag) and titanium dioxide (TiO2). The structural, optical, electrical, and dielectric properties of the resulting PVA-PVP/Ag-TiO2 nanocomposite electrolytes were analyzed. XRD analysis revealed that the PVA-PVP blend had a semicrystalline structure, and the addition of hybrid NPs reduced the crystallinity ratio. FTIR analysis showed that the intensity decreased as the content ratio of hybrid NPs increased. Optical measurements showed that the nanocomposite electrolyte samples' direct and indirect optical energy gap decreased with the increasing content of hybrid NPs. The electrical conductivity also increased with the hybrid NPs' content, likely due to the higher conductivity of the hybrid NPs compared to the polymer blend matrix's electrical conductivity. The dielectric constant (εr) and dielectric loss (εi) increased with the concentration of hybrid NPs at lower frequencies, indicating the polarization effects of space charges. The capacitance–frequency (C–f) and conductance–frequency (G/ω–f) curves of the prepared polymer nanocomposites exhibited a discernible enhancement correlating with the increased content of Ag-TiO2 nanofillers. The impedance spectroscopy data were analyzed using Nyquist plots, which showed a single semicircular arc whose radius of curvature decreased with increasing the hybrid NPs loading, indicating a decrease in the overall impedance of the nanocomposite electrolytes with the mixed NPs loading. The impedance reduction and dielectric feature increase were attributed to the interfacial polarization between the hybrid NPs and the polymeric matrix. These findings suggest that the PVA-PVP/Ag-TiO2 nanocomposite electrolytes could be used for thin-film dielectric capacitor applications.

Aligning TiO2 nanofiber for high ionic conductivity in cellulose acetate gel electrolytes

The escalating need for sustainable energy storage systems has prompted enhanced investigations into the advancement of environmentally acceptable, flame-retardant, and high-performing polymer gel electrolytes. The present study examines the ionic conductivity and electrochemical characteristics of gel polymer electrolytes (GPEs) based on cellulose acetate (CA) incorporated with disordered and electric-field-induced aligned TiO2 nanofibers. The results of our study indicate that the arrangement of nanofibers within the CA matrix significantly affects the electrical properties of these electrolytes. The highest ionic conductivity of GPEs containing randomly distributed nanofibers is 5.48 × 10−4 S/cm when the nanofiber content is 2.5 wt%. On the other hand, 2.5 wt% aligned nanofibers containing GPE shows a slightly higher room temperature ionic conductivity of 6.2 × 10−4 S/cm. Nevertheless, the alignment of these nanofibers strategically leads to a gradual enhancement in ionic conductivity, ultimately reaching its maximum value of 5.99 × 10−3 S/cm at a concentration of 10 wt% at room temperature. Significantly, the level of conductivity exhibited in this case is more than 1.5 orders higher than the conductivity observed in disordered nanofiber dispersion within the CA matrix. The improved performance can be due to the creation of long-distance conduction channels enabled by the alignment of nanofibers. The incorporation of well-aligned nanofibers into GPEs results in a high Li+ ion transference number of 0.71, an excellent electrochemical stability window of 4.9 V, and exceptional interfacial compatibility with metal electrodes. In addition, the polymer electrolytes exhibit improved flame-retardant properties when 10 wt% aligned nanofibers are added, enabling the samples to endure exposure to a flame for a period of 10 s. These results indicate the potential suitability of the nanocomposite gel polymer electrolytes (NCGPEs) for application in future advanced energy-storing systems. XRD, FTIR, and XPS investigations further confirm the ion-conduction features of the produced NCGPEs. The investigation of increased electrical characteristics of NCGPEs was supported by a detailed computer simulation conducted using density functional theory (DFT).

Effect Of Graphene Oxide on Poly (Methyl Methacrylate)-Grafted Natural Rubber Polymer Electrolytes

Polymer electrolytes (PE) are presently the subject of the majority of research due to their capacity to replace liquid electrolyte that suffer from high flammability and electrolyte leakage and also as a new forms of electrical power production and storage systems. Solid polymer electrolytes (SPE) typically have low ionic conductivity at room temperature because of the high crystallinity of the polymers. Methyl-grafted natural rubber has been studied extensively by a number of researchers due to its advantageous properties such as high flexibility, and ability to solvate inorganic salts to form a polymer-salt complex. Graphene oxide (GO) was used as a nanofiller, ammonium triflate (NH4CF3SO3) served as a dopant salt, and 30 % polymethyl methacrylate grafted natural rubber (MG30) served as the polymer host in the preparation of the nanocomposite polymer electrolyte (CPE) using the solution casting-method. Electrochemical impedance spectroscopy (EIS) was used to analyse the ionic conductivity of the samples, and Fourier-transform infrared spectroscopy (FTIR) was used to analyse the complexation between salt, polymer host and filler while Optical microscope was used to study the surface morphology of the prepared CPE samples. The decrease in peak strength for C=O in the FTIR spectra indicates the interaction between the polymer host and salt The sample containing 15 weight percent NH4CF3SO3 had the highest conductivity, which was 2.05×10-5 S cm-1. This substance has the potential to be used in energy storage devices like batteries and supercapacitors as an alternative to commercial liquid electrolyte.

Improving electrolyte performance: Nanocomposite solid polymer electrolyte films with cobalt oxide nanoparticles

AbstractThe present work gives an insight into the structural, thermal, and electrical analysis of novel nanocomposite solid polymer electrolyte films prepared using the solution casting technique by incorporating cobalt oxide nanoparticles into methyl cellulose‐magnesium acetate polymer electrolyte matrix. The impact of ceramic oxide on the complexation of the salt with the polymer chain is evident from FTIR analysis. The crystallinity of the electrolyte systems decreases upon the incorporation of nanofiller into the matrix. Electrochemical Impedance Analysis of the samples shows enhancement in the conductivity of the electrolytes. Nanocomposite electrolyte systems with 2 wt% (5.93 × 10−4 S/cm) and 3 wt% (5.77 × 10−4 S/cm) of cobalt oxide exhibit maximum room temperature ionic conductivity compared to other electrolyte systems. DSC thermogram reveals the creation of free volume in the matrix with the incorporation of the filler. A primary battery is fabricated using the nanocomposite electrolyte system with 3 wt% of the nanofiller, and its open circuit potential and discharge characteristics have been analyzed.Highlights Novel nanocomposite SPEs with cobalt oxide were prepared via solution casting. FTIR and XRD studies revealed modification in the microstructure. Cobalt oxide incorporation enhanced ionic conductivity of SPE. A primary battery fabricated using the highest conducting SPE.

Nanocomposite Solid Polymer Electrolytes with Polymer Blend (PVDF‐HFP/Pluronic) as Matrix and GO as Nanofiller: Preparation, Structural Characterization, and Lithium‐Ion Conductivity Analysis

AbstractNanocomposite solid polymer electrolytes (NSPEs) with PVDF‐HFP/Pluronic as blend polymer matrix, graphene oxide (GO) as nanofiller, and LiClO4 are reported. FTIR spectroscopy reveals the crystal phase transformation of PVDF‐HFP from nonpolar α phase to electroactive γ phase upon salt addition that suggests the ion‐dipole interaction between the salt and the matrix. Further, Pluronic not only hinders the PVDF crystallization that increases the amorphous character of the matrix but also interacts with the salt and hence assists in salt dissociation in the blend matrix. The dc conductivity of PVDF‐HFP/Pluronic/LiClO4 blend SPE improves with increasing the Pluronic content reaching 0.73 × 10−6 Scm−1 at room temperature with 60 wt.% Pluronic. The dispersion of GO in the same blend SPE leads to a significant jump in room temperature ion conductivity (≈1.2 × 10−6 Scm−1) with 0.4% GO. Temperature‐dependent ion conductivity of the NSPEs reveals an Arrhenius type thermally activated process. The dc polarization data indicates that the conductivity is predominantly due to ions. Impedance plots exhibit a distorted semicircle at higher frequency and a tilted spike at lower frequency. The spike is an indication of ion diffusion and electrode polarization effect. Further, GO also has enhanced the mechanical properties of the fabricated NSPEs.

Structural and Spectroscopic Investigation on Plasticized PEO/PMMA Blended Nanocomposite Solid Polymer Electrolytes

Structural and Spectroscopic Investigation on Plasticized PEO/PMMA Blended Nanocomposite Solid Polymer Electrolytes

Effect of KCl on the characteristics of Pvdf-Co-Hfp-based nanocomposite polymer electrolytes

Effect of KCl on the characteristics of Pvdf-Co-Hfp-based nanocomposite polymer electrolytes

High ionic conductivity upon low electrolyte uptake in TiO2 nanofiber-filled guar gum gel electrolytes

In nanocomposite gel polymer electrolytes (NCGPEs), high ionic conductivity is realized at a large electrolyte uptake ratio compromising the dimensional stability of the electrolyte films. The present work demonstrates interesting biodegradable gel polymer electrolytes based on guar gum (GG) dispersed with TiO2 nanofibers. Very high ionic conductivity of 2.3 × 10−3 Scm−1 at ambient temperature has been achieved at a relatively low electrolyte uptake ratio of 92% when nanofiber content in guar gum is 2.5 wt% ascertaining the role of nanofibers in promoting ion transport in NCGPEs. Nanofibers also empower the NCGPEs with higher electrochemical and interfacial properties making them a suitable candidate for energy storage systems of the next generation. The enhanced properties of NCGPEs induced by nanofibers have been supported by XRD, FTIR, XPS and computational studies.

Ionic Conductivity and Mechanical Reinforcement of Well-Dispersed Polymer Nanocomposite Electrolytes.

Nanoparticles are commonly added to polymer electrolytes to enhance both their mechanical and ion transport properties. Previous work reports significant increases in the ionic conductivity and Li-ion transference in nanocomposite electrolytes with inert, ceramic fillers. The mechanistic understanding of this property enhancement, however, assumes nanoparticle dispersion states─namely, well-dispersed or percolating aggregates─that are seldom quantified using small-angle scattering. In this work, we carefully control the inter-silica nanoparticle structure (where each NP has a diameter D = 14 nm) in a model polymer electrolyte system (PEO:LiTFSI). We find that hydrophobically modified silica NPs are stabilized against aggregation in an organic solvent by inter-NP electrostatic repulsion. Favorable NP surface chemistry and a strongly negative zeta potential promote compatibility with PEO and the resulting electrolyte. Upon prolonged thermal annealing, the nanocomposite electrolytes display structure factors with characteristic interparticle spacings determined by particle volume fraction. Thermal annealing and particle structuring yield significant increases in the storage modulus, G', at 90 °C for the PEO/NP mixtures. We measure the dielectric spectra and blocking-electrode (κb) conductivities from -100 to 100 °C, and the Li+ current fraction (ρLi+) in symmetric Li-metal cells at 90 °C. We find that nanoparticles monotonically decrease the bulk ionic conductivity of PEO:LiTFSI at a rate faster than Maxwell's prediction for transport in composite media, while ρLi+ does not significantly change as a function of particle loading. Thus, when nanoparticle dispersion is controlled in polymer electrolytes, Li+ conductivity monotonically, i.e., (κbρLi+), decreases but favorable mechanical properties are realized. These results imply that percolating aggregates of ceramic surfaces, as opposed to physically separated particles, probably are required to achieve increases in bulk, ionic conductivity.

New Network Polymer Electrolytes Based on Ionic Liquid and SiO2 Nanoparticles for Energy Storage Systems.

Elementary processes of electro mass transfer in the nanocomposite polymer electrolyte system by pulse field gradient, spin echo NMR spectroscopy and the high-resolution NMR method together with electrochemical impedance spectroscopy are examined. The new nanocomposite polymer gel electrolytes consisted of polyethylene glycol diacrylate (PEGDA), salt LiBF4 and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) and SiO2 nanoparticles. Kinetics of the PEGDA matrix formation was studied by isothermal calorimetry. The flexible polymer-ionic liquid films were studied by IRFT spectroscopy, differential scanning calorimetry and temperature gravimetric analysis. The total conductivity in these systems was about 10-4 S cm-1 (-40 °C), 10-3 S cm-1 (25 °C) and 10-2 S cm-1 (100 °C). The method of quantum-chemical modeling of the interaction of SiO2 nanoparticles with ions showed the advantage of the mixed adsorption process, in which a negatively charged surface layer is formed from Li+ BF4- ions on silicon dioxide particles and then from ions of the ionic liquid EMI+ BF4-. These electrolytes are promising for use both in lithium power sources and in supercapacitors. The paper shows preliminary tests of a lithium cell with an organic electrode based on a pentaazapentacene derivative for 110 charge-discharge cycles.

Improving the polyethylene oxide/carboxymethyl cellulose blend's optical and electrical/dielectric performance by incorporating gold quantum dots and copper nanoparticles: nanocomposites for energy storage applications

Herein, nanocomposite polymer electrolyte films were prepared from the blend of two polymers, polyethylene oxide (PEO) and carboxymethyl cellulose (CMC), stuffed with various contents of gold quantum dots (AuQDs) and copper nanoparticles (CuNPs) as hybrid nanofiller via the solution casting method. AuQDs were prepared using laser ablation in liquid (LAL). TEM images showed that the average size of AuQDs is nearly 6.21 nm with a spherical shape. The effects of AuQDs and the hybrid nano-filler (AuQDs and CuNPs) on the PEO/CMC blend structural, optical, and electrical/dielectric characteristics have been investigated and discussed. XRD results revealed that the crystallinity degree of the nanocomposite samples decreased with increasing AuQDs/CuNPs content. Also, UV–Vis spectroscopy analysis uncovered that the optical energy gap reduced as the hybrid nanofillers' content increased. At room temperature, the electrical impedance spectroscopy (EIS) measurements showed that the hybrid nanofiller loading increases the electrolyte films’ electrical conductivity. In the dielectric properties, space charges polarization revealed higher values, where the dielectric constant (ε′) increased at lower frequency regions. The Nyquist diagram showed a semicircular shape at the lower frequencies part with a linear shape at the higher frequencies part with decreasing radius; two equivalent circuit models could be the best fit. These results suggest that these nanocomposite electrolyte films could be candidates for capacitors and flexible energy storage devices.

Novel nanoarchitecture of 3D ion transfer channel containing nanocomposite solid polymer electrolyte membrane based on holey graphene oxide and chitosan biopolymer

In the arena of three-dimensional (3D) nanoarchitecture, holey graphene oxide (HGO)—a class of two-dimensional (2D) graphene oxide porous nanosheet, has emerged as a promising choice of additive material to design advanced 3D nanocomposite for energy and environmental applications. With a facile and cost-effective solution-casting technique, we fabricated here a flexible, wearable, free-standing, and super-thin (∼0.08 mm) solid polymer electrolyte membrane (SPEM) consisting of 2D-HGO, lithium bis(trifluromethanesulfonyl)imide (LiTFSI) salt, polyvinylpyrrolidone (PVP) polymer binder, and chitosan (CH) biopolymer. SPEM exhibited impressive ionic conductivity of 2.76 × 10-3 S⋅cm−1 at room temperature (RT = 23 °C) which is comparable to liquid electrolytes. Robust mechanical property (5.87 MPa) and easy lithium-ion diffusion capability of SPEM were identified by the ultra-low activation energy (Ea) of 0.089 eV, which is one of the best values among the reported solid polymer electrolytes. Good lithium-ion transference number (tLi+= 0.76) and wide electrochemical stability window (ESW = 4.4) indicated single ion conduction and stable battery operation voltage capability of SPEM. Moreover, fast ion transfer mechanism of SPEM was proposed according to the comprehensive characterizations; mostly relating to uniform and strong interconnecting novel 3D ion transferring routes. Temperature and frequency responsive charge carrier mobility trend were also investigated with an in-depth dielectric study. Promising RT galvanostatic Li plating-stripping performance was observed at 5 mA⋅cm−2 with a hybrid symmetric cell. Using Li metal as anode, SPEM, and LiCoO2 as cathode in the full cell, a good RT specific discharge capacity of 142.8 mA⋅h⋅g−1 was achieved at 0.1 C rate.

Dye-sensitized solar cells based on nanocomposite gel polymer electrolytes incorporating modified-CuO nanorod prepared by varying sonication durations

Dye-sensitized solar cells based on nanocomposite gel polymer electrolytes incorporating modified-CuO nanorod prepared by varying sonication durations

Synergistic effect of silica-covered graphene oxide (in-situ) hybrid nanocomposites for use as a polymer electrolyte membrane for fuel cell applications

Herein, an efficient nanocomposite polymer electrolyte membrane has been designed by the synergistic combination of graphene oxide and SiO2 by following a facile and cost-effective in-situ synthesis method. The successful formation and covalent attachment of the SiO2 nanoparticles over the G surface have been validated from FTIR, XRD, Raman and TGA studies. The surface morphologies with even dispersion capacity and particle size of the synthesized nanoparticles were also studied from FESEM-EDS, TEM, and particle size analyser, respectively. Then the GS/PVDF-co-HFP nanocomposite membranes were prepared via solution casting followed by functionalization with chlorosulfonic acid. These new sulfonated PVDF-co-HFP-based SiO2-covered graphene oxide nanocomposite membranes (SPCGS) had improved properties attributing to increased water absorption, ion exchange capacities, and increased proton conductivities. Further, the barrier effect rendered by the GS nanoparticles assists in decreased methanol permeability of the SPCGS membranes due to the tortuosity of the methanol flow channels. The potentiality of the membrane was further assessed from chemical structure analysis, and morphological, thermal, and mechanical analyses like FTIR, NMR, XRD, FESEM-EDS, TGA and UTM, etc. Interestingly, the membrane selectivity has been enhanced up to 3.58 × 105 S.scm−3 thereby depicting the potentiality of SPCGS membranes in DMFC.

Graphene Oxide-Grafted Hybrid Diblock Copolymer Brush (GO-graft-PEG6k-block-P(MA-POSS)) as Nanofillers for Enhanced Lithium Ion Conductivity of PEO-Based Nanocomposite Solid Polymer Electrolytes.

Nanocomposite solid polymer electrolytes (NSPEs) with PEO as the matrix and (i) GO or (ii) GO-graft-PEG6k or (iii) GO-graft-PEG6k-block-P(MA-POSS) as nanofillers have been fabricated to elucidate the impact of the filler morphology on the lithium ion conductivity. GO-graft-PEG6k was obtained by grafting PEG6k onto GO via esterification. GO-graft-PEG6k-block-P(MA-POSS) was prepared via surface-initiated atom transfer radical polymerization. Fourier-transform infrared spectroscopy revealed enhanced salt dissociation and complexation between the filler and PEO host that could be attributed to Lewis acid-base interactions. Electrochemical impedance spectroscopy revealed the improved ion conductivity of the fabricated NSPEs as compared with the pristine PEO-LiClO4. As an example, at 50 °C, the ion conductivity increased to 4.01 × 10-5 and 6.31 × 10-5 S cm-1 with 0.3% GO and 0.3% GO-graft-PEG6k, respectively, from 2.36 × 10-5 S cm-1 of PEO-LiClO4, suggesting that the filler with brush-like architecture (GO-graft-PEG6k) is more efficient in enhancing the ion conductivity. Further increase in filler content resulted in lowering of the ion conductivity that could be ascribed to aggregation of the filler. The most dramatic impact on conductivity was observed with the incorporation of brush-like GO-graft-PEG6k-block-P(MA-POSS) as a nanofiller (3.0 × 10-4 S cm-1 at 50 °C with 1.0 wt % filler content). The increase in ion conductivity in the current systems, as opposed to the conventional view, could not be correlated with the content of the amorphous phase of the matrix. The conduction mechanism is still unclear; nevertheless, it could be assumed that in addition to the ion conduction through the PEO matrix, the filler forms additional low-energy ion conducting channels at its interface with the matrix. The pendent POSS nanocages of GO-graft-PEG6k-block-P(MAPOSS) might probably increase the free volume at the interface with the matrix that is associated with higher chain and ion mobility, thus further enhancing the ion conductivity as compared with GO and GO-graft-PEG6k. The faster ion dynamics in 1.0 wt % GO-graft-PEG6k-block-P(MAPOSS) NSPEs has also been verified by the dielectric relaxation studies. Thus, integration of both the PEG and POSS nanocages into GO-grafted brush-like architecture offers a new tool for tuning the lithium ion conductivity for potential Li ion battery applications.

Gellan Gum-Montmorillonite Nanocomposites for Electrochromic Devices

The present paper shows the results of nanocomposite polymer electrolytes (SPEs) of montmorillonite (MMT; Na+SYN-1) and gellan gum obtained by the solution casting method. The membrane samples were characterized by ATR-FTIR, time-domain nuclear magnetic resonance (TD-NMR), and scanning electron microscopy (SEM). Then, two samples were chosen and applied in small electrochromic devices (ECDs). The ATR-FTIR revealed shifts in bands of acetate and glycosidic bonds at 1032 and 1611 cm−1, respectively, indicating an interaction between the gellan gum and Na+SYN-1. The spin–lattice relaxation time of the proton nuclei (T1) suggests the poor dispersion of MMT in the matrix, especially above 20 wt.%. However, SEM pictures pointed to a more homogeneous surface of the nanocomposite containing 40 wt.% Na+SYN-1 when compared to the sample without clay. NPEs with 10 and 40 wt.% Na+SYN-1 were applied in ECDs, and the voltammograms showed a decrease in anodic and cathodic peaks after 2519 chronocoulometric cycles for the sample with 10 wt.% Na+SYN-1 and after 420 cycles for the sample with 40 wt.% Na+SYN-1. There was also a decrease in the charge density in both ECDs and an oscillating difference in transmittance between the colored/discolored states during the chronocoulometric cycles of the ECD with GG-MMT10. Further studies may reveal more property improvements in gellan gum nanocomposites.