Nanocomposite Gel Electrolytes Research Articles

Synthesis and performance assessment of silica dispersed nano-composite polymer gel electrolyte for high-performance solid-state supercapacitors

Nano-composite polymer gel electrolyte (NCPGE) films are prepared by incorporating liquid electrolyte (EC-PC-TEABF4) into polyvinyldinefloroide co-hexafluoropropylene (PVDF-HFP) polymer with dispersed SiO2 nano-particles using solution cast technique. The NCPGE is optimized for the highest ionic conductivity by varying wt% of SiO2 nanoparticles in PGE [(1:4){PVDF-HFP + EC-PC-TEABF4}]. Highest conductivity of 8.2 × 10−3 Scm−1 is found for optimized composition [(1:4){PVDF-HFP + EC-PC-TEABF4} + SiO2 (15 wt%)] of NCPGE. Structural and morphological studies have been done using XRD, FTIR, and SEM. Frequency dependent dielectric behaviour is understood using dielectric constant and modulus analysis in a wide range of frequencies. The ionic transference number is 0.96 and an electrochemical potential window of ∼ 3.5 V has been obtained. Fabrication of electric double layer capacitor (EDLC) is done by sandwiching NCPGE between activated carbon (AC) electrodes. The electrochemical performance of fabricated supercapacitor is evaluated by impedance spectroscopy, cyclic voltammetry, and galvanostatic charge–discharge techniques. Results show significant improvement in the quality of synthesized electrolyte.

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.

Effect of the Solvate Environment of Lithium Cations on the Resistance of the Polymer Electrolyte/Electrode Interface in a Solid-State Lithium Battery.

The effect of the composition of liquid electrolytes in the bulk and at the interface with the LiFePO4 cathode on the operation of a solid-state lithium battery with a nanocomposite polymer gel electrolyte based on polyethylene glycol diacrylate and SiO2 was studied. The self-diffusion coefficients on the 7Li, 1H, and 19F nuclei in electrolytes based on LiBF4 and LiTFSI salts in solvents (gamma-butyrolactone, dioxolane, dimethoxyethane) were measured by nuclear magnetic resonance (NMR) with a magnetic field gradient. Four compositions of the complex electrolyte system were studied by high-resolution NMR. The experimentally obtained 1H chemical shifts are compared with those theoretically calculated by quantum chemical modeling. This made it possible to suggest the solvate shell compositions that facilitate the rapid transfer of the Li+ cation at the nanocomposite electrolyte/LiFePO4 interface and ensure the stable operation of a solid-state lithium battery.

Nanofiber induced enhancement of electrical and electrochemical properties in polymer gel electrolytes for application in energy storage devices

In this article, a significant study on ionic conduction properties of novel nanocomposite polymer gel electrolytes (NCPGEs) is carried out using poly (methyl methacrylate) (PMMA) with nanofibers of silica (SiO2) complexed with lithium perchlorate (LiClO4) by combining experimental work and computational modelling. The compositional variation of SiO2 nanofibers in polymer electrolytes induces a visible alteration in different characteristics like ionic conductivity, electrochemical stability, interfacial stability, surface morphology and optical properties. Among all the compositions, NCPGEs containing 5 wt% nanofibers exhibit maximum ionic conductivity of 4.6 × 10−3 Scm−1 at room temperature. Fourier Transform Infrared Spectroscopy (FTIR) has shown a better interaction between lithium ions (Li+) with carbonyl group of PMMA in presence of SiO2 nanofibers. X-ray photoelectron spectroscopy (XPS) has confirmed various interactions among different constituents in NCPGEs. A combined molecular dynamics (MD) simulation and density functional theory (DFT) show a stable interaction between polymer with nanofiber filler and Li salt.

Nanocomposite polymer gel with dispersed alumina as an efficient electrolyte for application in supercapacitors

A nanocomposite polymer gel electrolyte (NCPGE) has been synthesized from polyvinylidene fluoride co-hexafluoropropylene (PVDF-HFP) as the host polymer, ethylene carbonate (EC)/propylene carbonate (PC) as plasticizers, and tetraethylammonium tetrafluoroborate (TEABF4) as an ionic salt by a solution-casting technique, followed by the addition of Al2O3 nanoparticles. The optimal loading of Al2O3 giving the highest ionic conductivity of 6.0 × 10−3 S cm−1 was found to be 18 wt%. An activation energy of 0.107 eV has been calculated from a temperature-dependent conductivity plot, which shows Arrhenius behavior. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) characterizations have been applied to investigate the morphology and structure. The semi-crystalline and porous nature of the NCPGE has been confirmed by SEM and XRD analyses. The ionic transference number was calculated as 0.98 by the DC polarization technique, confirming the dominant ionic nature of the prepared electrolyte. The electrochemical potential window of the NCPGE of about 3.4 V, as estimated by linear sweep voltammetry, makes it suitable for supercapacitor applications.

Conductivity increase effect in nanocomposite polymer gel electrolytes: manifestation in the IR spectra

Nanocomposite polymer electrolytes based on poly(ethylene glycol) diacrylate and 1 M LiBF4 solution in γ-butyrolactone containing SiO2 nanoparticles were studied by FT IR spectroscopy. Quantum chemical modeling of five different solvate complexes of ions composed of LiBF4 with solvent molecules was carried out and their theoretical IR spectra were calculated. The compositions of the solvate complexes of LiBF4 in the nanocomposite gel electrolyte were studied by comparing the experimental and theoretical IR spectra. It was concluded that the conductivity peak observed upon adding 2 wt.% SiO2 is due to the appearance of mobile ions as a consequence of ionic dissociation on the surface of nanoparticles at their optimal configuration.

Study of PVA-based nanocomposite polymer gels containing weak aliphatic dicarboxylic acids

In this study, nanocomposite polymer gel electrolytes have been prepared by using nanosize fumed silica (SiO2), poly(vinyl alcohol) (PVA), dimethyl sulfoxide (DMSO) and weak aliphatic acids (oxalic acid (OA), malonic acid (MA) and succinic acid (SA) with different dissociation constant values) and characterized by ionic conductivity, pH and viscosity studies. The ionic conductivity of liquid electrolytes has been found to depend on the dissociation constant values of the acids, which has been explained on the basis of the inductive effect. The decrease in the ionic conductivity of electrolytes observed with the addition of a polymer has been explained as being due to the increase in viscosity. The increase in the conductivity of gel electrolytes with the addition of nanofillers has been explained by using the double-percolation-threshold model. Maximum room-temperature conductivities of 2·12 × 10−3, 7·3 × 10−4 and 5·8 × 10−4 S/cm have been obtained for nanocomposite gel electrolytes containing DMSO + 1 M OA, MA and SA + 10 wt% PVA at 6 wt% silica, respectively.

Ionic liquid mediated nano-composite polymer gel electrolyte for rechargeable battery application

ABSTRACTNano-composite polymer gel electrolytes (NPGEs) based on polymer poly(vinylidene fluoride-co-hexafluoropropylene) PVdF-HFP, ionic liquid, 1-butyl-3- methylimidazolium bis(trifluoromethanesulfonyl)imide BMIMTFSI, Li-salt along with the addition of SiO2 nanoparticles have been synthesized and characterized by various techniques. Prepared NPGEs show high room temperature ionic conductivity (~10−3 S/cm) and have a wide electrochemical window (ECW) (~3.3–3.5 V). The galvanostatic charge/discharge profile was studied by sandwiching best performing NPGEs between a LiFePO4 cathode and lithium metal anode. The specific discharge capacity of the cell (Li/NPGE/LiFePO4) room temperature at 0.1C rate is found to be 138 mAh/g.

Specific Features of Ion Transport in New Nanocomposite Gel Electrolytes Based on Cross-Linked Polymers and Silica Nanoparicles

The spesific features of ion transport are studied in the nanocomposite system based on a network matrix synthesized by radical polymerization of polyethylene glycol diacrylate in the presence of liquid aprotic electrolyte containing 1 M LiBF4 in γ-butyrolactone and SiO2 nanopowder. The self-diffusion coefficients measured by 7Li NMR spectroscopy with pulsed field gradient have a maximum at 2 wt % SiO2 nanoparticles. Nanocomposites of the latter composition exhibit the highest cation transport numbers (0.49) and the maximum of conductivity in the temperature interval under study (from –70 to 100°С): 4 mS/cm at 20°С and 1 mS/cm at –70°С. The second conductivity maximum at 6 wt % is characterized merely by the low effective activation energy of conduction. Possible mechanisms are invoked to explain the increase in conductivity. The first mechanism is based on the increase in the number of mobile charge carriers which may be a result of salt dissociation to ions, the second mechanism is associated with the development of a large number of favorable pathways for ion transport.

Fabrication of Al2O3/IL‐Based Nanocomposite Polymer Electrolytes for Supercapacitor Application

AbstractIn the present work, we investigated physical properties as well as supercapacitor application of nanocomposite polymer gel electrolytes. The polymer electrolyte (PE) consists of Ionic Liquid, (1‐Ethyl‐3‐methyl‐imidazolium tetrafluoroborate (IL)) as a softening agent, aluminum oxide (Al2O3) as a nano additive and sulfonated polysulfone (SPSU) as the main polymer. The resulting nanocomposite gel polymer electrolyte structure was characterized using spectroscopic methods. Thermal characteristic properties of polymeric nanocomposites were investigated by performing differential scanning calorimetry (DSC) and terhmogravimetric analysis (TGA). Conductivity measurements of the materials were obtained between −20 °C and 100 °C at varying temperature intervals. The highest ionic conductivity values were obtained from the SPSU / 0.1 IL and SPSU / 5% Al2O3 / 0.2 IL polymer electrolyte structures as 2.5 x10−4 and 2.06 x10−3 S cm−1 at 100 °C, respectively. The maximum specific capacitance value of 144 F g−1 was obtained from SPSU / 5% Al2O3 / 0.2 IL polymer electrolyte based system at a current density of 1 A g−1. The supercapacitor reached an energy density of 20 Wh kg−1 at a power density of 1028 W kg−1. In addition, the supercapacitor has shown a remarkable capacitance retention with a performance loss of only about 10% after 5000 cycles.

Quasi-Solid-State Dye-Sensitized Solar Cells for Efficient and Stable Power Generation under Room Light Conditions

Highly efficient quasi-solid-state dye-sensitized solar cells (QS-DSSCs) are fabricated using nanocomposite gel electrolytes and applied under room light conditions (200 lx). To obtain high energy conversion efficiency in QS-DSSCs, the important components of the DSSC are systematically optimized based on their performance in liquid-state DSSCs. It shows that the liquid cell using the 3-methoxypropionitrile-based cobalt electrolyte has higher efficiency (18.91%) than the cell using the acetonitrile-based electrolyte (17.82%) under 200 lx illumination due to the higher charge recombination resistance at the photoelectrode/electrolyte interface for the 3-methoxypropionitrile system. Poly(vinylidene fluoride-co-hexafluoropropylene) is utilized as the gelator of the liquid electrolytes to prepare polymer gel electrolytes. Furthermore, to improve the performance of the QS-DSSCs, different metal oxide nanoparticles are introduced as nanofillers of the polymer gel electrolytes. It shows that the zinc oxide nanof...

Iodine-free nanocomposite gel electrolytes for quasi-solid-state dye-sensitized solar cells

Iodine-free quasi-solid-state electrolytes were developed for dye-sensitized solar cells (DSSCs) by removing I2 from the conventional I−/I3− redox electrolyte and gelling the electrolyte with metal oxide nanoparticles. The inorganic nanoparticles played a dual role of gelling agent and charge transport enhancer. The removal of I2 improved the long-term stability of DSSCs, but reduced the ionic diffusivity of electrolyte and thus the solar-to-electricity efficiency of DSSCs. By introducing a suitable nanoparticle gelator into the electrolyte, the ionic diffusivity and the interfacial charge transfer could be enhanced due to the formation of 3-D networks that facilitate Grotthuss-type ion exchange. Three different metal oxide nanoparticles (SiO2, TiO2, and ZnO) were evaluated, and the best performance was obtained by TiO2 nanoparticles. The I2-free quasi-solid-state DSSCs gelled by 15% TiO2 achieved an efficiency of 8.00% vs. a 6.94% efficiency attained by the I2-free liquid-state reference cells. The I2-free quasi-solid-state DSSCs gelled by 15% TiO2 also exhibited good long-term at-rest stability with an estimated life span of five to six years under ambient condition based on an accelerated stability test performed at 65°C with 65% relative humidity.

Development of Quasi‐Solid‐State Dye‐Sensitized Solar Cells Based on a Poly (vinyl alcohol)/Poly (ethylene glycol)/Functionalized Multi‐Walled Carbon Nanotubes Gel Electrolyte

AbstractA series of quasi‐solid state dye sensitized solar cells (DSSCs) were fabricated with different wt % of carboxy functionalized multi walled carbon nanotubes (c‐MWCNTs) containing poly (vinyl alcohol)/poly (ethylene glycol) gel electrolyte. The structure and morphology of the polymeric gel electrolyte were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive X‐ray spectrum (EDX) analyses. The thermal stability of the polymeric gel electrolyte was evaluated by thermogravimetric analysis. Fabrication of the DSSCs were carried out by sandwiching the poly (vinyl alcohol)/poly (ethylene glycol)/ c‐MWCNT nanocomposite gel electrolyte in between the dye sensitized TiO2 photoanode and platinum‐based counter electrode. However, c‐MWCNTs forms network with channels of PVA/PEG matrix in gel electrolyte which reduces the charge transfer resistance (Rct) of DSSCs, thereby significantly improving the photovoltaic properties of the DSSCs. The maximum photo conversion efficiency (η) of 3.5 % and short circuit current density (Jsc) of 8.80 mAcm‐2 was achieved using an optimum loading of 0.5 % c‐MWCNT.

Electrical Behavior of Nano-Composite Polymer Gel Electrolytes Containing Weak Acid for Proton Batteries: Role of Donor Number of Solvent and Nano-Filler

Electrical Behavior of Nano-Composite Polymer Gel Electrolytes Containing Weak Acid for Proton Batteries: Role of Donor Number of Solvent and Nano-Filler

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.

Quantum chemical modeling of the degradation of the polymer matrix and solvent molecules in nanocomposite polymer gel electrolytes

Quantum chemical calculations of molecular structures and magnetic shielding constants for H and C nuclei were performed by the density functional method. The structures of the polyester diacrylate degradation products formed under sonication in the presence of TiO2 or Li2TiO3 nanoparticles in the electrolyte polyester diacrylate—LiClO4—ethylene carbonate—nanopowder were proposed based on agreement of the goodness-of-fit with the experimental NMR spectra of the polymer electrolytes. The surface centers on TiO2 and Li2TiO3 under the ultrasonic energy absorption conditions were concluded to catalyze the unexpected metathesis of σ-C—H bonds in the α-positions to the carbonyl group.

Preparation of Nano-composite Gel Electrolytes with Metal Oxide Additives for Dye-sensitized Solar Cells

The dye-sensitized solar cell (DSSC) has been widely studied due to the low-cost and interesting efficiencies. The solar-to-electricity conversion efficiency (η) is an important factor governing the performance of DSSC, so is the long-term stability. In this study, three kinds of inorganic nanoparticles, i.e., SiO2, TiO2, and ZnO, are employed to solidify an acetonitrile-based liquid electrolyte for quasi-solid-state DSSCs based on ZnO photoanodes. The concentrations of I2 and LiI in the liquid electrolyte are first optimized with respect to the diffusion-limited current density of I3− ions and the photovoltaic performance of DSSC. Different amounts of the inorganic nanoparticles are then introduced into the optimized liquid electrolyte to accomplish gelation for quasi-solid-state DSSCs. All the nanoparticles tested can accomplish gelation while achieving a η higher than the reference liquid-state cell. The highest η of 4.17% was recorded for quasi-solid-state DSSCs under simulated full sunlight (AM1.5G, 100mW/cm2) with 35.0wt% ZnO nanoparticles as the gelator. This is due to an enhancement in short-circuit current density and open-circuit voltage as a result of efficient charge transfer channels and improved electron lifetime generated by the gelling nanoparticles. The electrochemical impedance spectroscopy was also applied to analyze the interfacial resistances in the devices. The optimized quasi-solid-state DSSC also shows excellent at-rest stability exhibiting 95% retention of the η value after 150days of storage.

Stable Lithium Deposition Generated from Ceramic-Cross-Linked Gel Polymer Electrolytes for Lithium Anode.

In this work, a composite gel electrolyte comprising ceramic cross-linker and poly(ethylene oxide) (PEO) matrix is shown to have superior resistance to lithium dendrite growth and be applicable to gel polymer lithium batteries. In contrast to pristine gel electrolyte, these nanocomposite gel electrolytes show good compatibility with liquid electrolytes, wider electrochemical window, and a superior rate and cycling performance. These silica cross-linkers allow the PEO to form the lithium ion pathway and reduce anion mobility. Therefore, the gel not only features lower polarization and interfacial resistance, but also suppresses electrolyte decomposition and lithium corrosion. Further, these nanocomposite gel electrolytes increase the lithium transference number to 0.5, and exhibit superior electrochemical stability up to 5.0 V. Moreover, the lithium cells feature long-term stability and a Coulombic efficiency that can reach 97% after 100 cycles. The SEM image of the lithium metal surface after the cycling test shows that the composite gel electrolyte with 20% silica cross-linker forms a uniform passivation layer on the lithium surface. Accordingly, these features allow this gel polymer electrolyte with ceramic cross-linker to function as a high-performance lithium-ionic conductor and reliable separator for lithium metal batteries.

Enhancement in Electrical Properties of PEO Based Nano-Composite Gel Electrolytes

Enhancement in Electrical Properties of PEO Based Nano-Composite Gel Electrolytes

Tough nanocomposite ionogel-based actuator exhibits robust performance.

Ionogel electrolytes can be fabricated for electrochemical actuators with many desirable advantages, including direct low-voltage control in air, high electrochemical and thermal stability, and complete silence during actuation. However, the demands for active actuators with above features and load-driving ability remain a challenge; much work is necessary to enhance the mechanical strength of electrolyte materials. Herein, we describe a cross-linked supramolecular approach to prepare tough nanocomposite gel electrolytes from HEMA, BMIMBF4, and TiO2 via self-initiated UV polymerization. The tough and stable ionogels are emerging to fabricate electric double-layer capacitor-like soft actuators, which can be driven by electrically induced ion migration. The ionogel-based actuator shows a displacement response of 5.6 mm to the driving voltage of 3.5 V. After adding the additional mass weight of the same as the actuator, it still shows a large displacement response of 3.9 mm. Furthermore, the actuator can not only work in harsh temperature environments (100°C and −10°C) but also realize the goal of grabbing an object by adjusting the applied voltage.