Conductivity Of Gel Electrolytes Research Articles

Synergistic effects of polyvinylidene fluoride (PVDF) and polyvinylpyrrolidone (PVP) blends in gel electrolytes for efficient and long-term stability in dye-sensitized solar cells (DSSCs)

In this work, the stability issues associated with liquid electrolyte-based dye-sensitized solar cells (DSSC) have been addressed by introducing polymer gel electrolytes. The synergistic combination of polyvinylidene fluoride (PVDF) and polyvinylpyrrolidone (PVP) has been achieved through solution blending. Ionic conductivity measurements, scanning electron microscopy, X-ray diffraction analysis, and Fourier transform infrared spectroscopy have been employed for analysis. Optimal cohesiveness was observed at PVP concentrations exceeding 40 %, with the best outcomes achieved at a 50 % PVDF-PVP weight ratio. The electrolyte solution, comprising the polymer blend, suitable solvents, and iodine-based salts, exhibits peak conductivity (2.33 mScm⁻1) at a 10 % salt content. DSSCs utilizing the PVDF & PVP polymer blend gel electrolytes demonstrate enhanced durability and maintained efficiency at 5.43 %, exhibiting only a modest 12 % reduction compared to liquid electrolyte counterparts. Over two weeks, the fabricated DSSCs exhibited consistent photovoltaic performance, while conventional cells experienced significant declines in short-circuit current (36 %) and open-circuit voltage (33.33 %). This study signifies a promising advancement in solar cell technology, showcasing improved stability and performance in DSSCs using conductive polymer blend gel electrolytes.

Quasi-solid polyaniline/poly(vinyl pyrrolidone) blend electrolytes for dye-sensitized solar cells

Conductive polymer blend gel electrolytes can address the instability caused by liquid electrolytes in dye-sensitized solar cells (DSSCs), thereby improving their long-term stability, by reducing leakage, and enhancing electrode adhesion. This work employed in-situ polymerization to synthesize blends of polyvinylpyrrolidone (PVP) and polyaniline (PANI), which were subsequently characterized using ionic conductivity measurements, Scanning Electron Microscopy, X-ray diffraction analysis, and Fourier Transform Infrared Spectroscopy. Consequently, the optimal composition has been chosen to prepare the electrolyte solution using polymer blend, solvents, and iodine-based salts. The conductivity of blend electrolytes has also been found to be affected by the salt concentration. The fabrication of DSSCs has made use of electrolytes with the highest conductivity values. It has been found that dye-sensitized solar cells with polymer gel electrolytes are more robust but less efficient than their conventional counterparts. Solid-state dye-sensitized solar cells were found to maintain their photovoltaic performance for a duration of one week, whereas conventional cells experienced a substantial decline in short-circuit current (∼36%) and open-circuit voltage (∼33.33%) over the same period.

Dynamic Networks of Cellulose Nanofibrils Enable Highly Conductive and Strong Polymer Gel Electrolytes for Lithium‐Ion Batteries

AbstractTunable dynamic networks of cellulose nanofibrils (CNFs) are utilized to prepare high‐performance polymer gel electrolytes. By swelling an anisotropically dewatered, but never dried, CNF gel in acidic salt solutions, a highly sparse network is constructed with a fraction of CNFs as low as 0.9%, taking advantage of the very high aspect ratio and the ultra‐thin thickness of the CNFs (micrometers long and 2–4 nm thick). These CNF networks expose high interfacial areas and can accommodate massive amounts of the ionic conductive liquid polyethylene glycol‐based electrolyte into strong homogeneous gel electrolytes. In addition to the reinforced mechanical properties, the presence of the CNFs simultaneously enhances the ionic conductivity due to their excellent strong water‐binding capacity according to computational simulations. This strategy renders the electrolyte a room‐temperature ionic conductivity of 0.61 ± 0.12 mS cm−1 which is one of the highest among polymer gel electrolytes. The electrolyte shows superior performances as a separator for lithium iron phosphate half‐cells in high specific capacity (161 mAh g−1 at 0.1C), excellent rate capability (5C), and cycling stability (94% capacity retention after 300 cycles at 1C) at 60 °C, as well as stable room temperature cycling performance and considerably improved safety compared with commercial liquid electrolyte systems.

Flexible Sustained Ionogels with Ionic Hyperbranched Polymers for Enhanced Ion-Conduction and Energy Storage.

Flexible and mechanically robust gel-like electrolytes offer enhanced energy storage capabilities, versatility, and safety in batteries and supercapacitors. However, the trade-off between ion conduction and mechanical robustness remains a challenge for these materials. Here, we suggest that the introduction of ionic hyperbranched polymers in structured sustained ionogels will lead to both enhanced ion conduction and mechanical performance because of the hyperbranched polymers' ionically conductive groups and the complementary interfacial interactions with ionic liquids. More specifically, we investigate the effect of hyperbranched polymers with carboxylate terminal groups and imidazolium counterions with various ionic group densities on the properties of ionogels composed of coassembled cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs) as sustainable open pore frame for ionic liquid immersion. The addition of hyperbranched polymers leads to the formation of highly interconnected openly porous, lightweight, and shape-persistent materials by harnessing hydrogen bonding between the polymers and the CNFs/CNCs "frame". Notably, these materials possess a 2-fold improvement in ionic conductivity combined with many-fold increase in Young's modulus, tensile strength, and toughness, making them comparable to common reinforced nanocomposite materials. Furthermore, the corresponding thin-film gel supercapacitors possess enhanced electrochemical cycling stability upon repeated bending with an 85% capacitance retention after 10 000 cycles, promising new insight in the development of simultaneously conductive and flexible gel electrolytes with sustained performance.

Isomeric effects of poly-viologens on electrochromic performance and applications in low-power electrochemical devices

Electrochromic (EC) behaviors of poly-viologens are tuned by selecting positions ( ortho ( o ) , meta ( m ), and para ( p )) of the benzene rings linked to 4,4′-bipyridine. All-in-one type EC devices (ECDs) are conveniently fabricated by adding poly-viologens to highly conductive solid-state polymeric gel electrolytes. The maximum transmittance contrast (Δ T ) of the o -poly-viologen based ECD is much lower than that of the other isomers, and its bleaching is not reversible, whereas a large Δ T and high stability are achieved with the m - and p -poly-viologens. Considering the high solubility of the m -poly-viologen in ion gels, it is anticipated to have a larger hydrodynamic size, leading to low diffusivity (∼1.1 × 10 −12 cm 2 /s for cationic and ∼2.7 × 10 −12 cm 2 /s for anionic current). As a result, the m -poly-viologen ECD shows a superior memory effect and long-lasting colored state without voltage supply. This feature allows us to demonstrate a low-power ECD based on the m -poly-viologen, which only requires ∼3.54 μW/cm 2 to maintain the transmittance below 30%. The results indicate that adjusting the isomeric molecular structure of poly-viologen EC chromophores is an effective way to control their EC performance. • Three isomeric poly-viologens are designed and synthesized for electrochromic (EC) chromophores. • Poly-viologens with a larger hydrodynamic size exhibit a lower diffusivity and a higher memory effect. • EC devices with meta -poly-viologens consume very low power of ∼3.54 μW/cm 2 to maintain colored state.

Single-Ion Conducting Polymer Nanoparticles as Functional Fillers for Solid Electrolytes in Lithium Metal Batteries

Composite solid electrolytes including inorganic nanoparticles or nanofibers which improve the performance of polymer electrolytes due to their superior mechanical, ionic conductivity, or lithium transference number are actively being researched for applications in lithium metal batteries. However, inorganic nanoparticles present limitations such as tedious surface functionalization and agglomeration issues and poor homogeneity at high concentrations in polymer matrixes. In this work, we report on polymer nanoparticles with a lithium sulfonamide surface functionality (LiPNP) for application as electrolytes in lithium metal batteries. The particles are prepared by semibatch emulsion polymerization, an easily up-scalable technique. LiPNPs are used to prepare two different families of particle-reinforced solid electrolytes. When mixed with poly(ethylene oxide) and lithium bis(trifluoromethane)sulfonimide (LiTFSI/PEO), the particles invoke a significant stiffening effect (E′ > 106 Pa vs 105 Pa at 80 °C) while the membranes retain high ionic conductivity (σ = 6.6 × 10–4 S cm–1). Preliminary testing in LiFePO4 lithium metal cells showed promising performance of the PEO nanocomposite electrolytes. By mixing the particles with propylene carbonate without any additional salt, we obtain true single-ion conducting gel electrolytes, as the lithium sulfonamide surface functionalities are the only sources of lithium ions in the system. The gel electrolytes are mechanically robust (up to G′ = 106 Pa) and show ionic conductivity up to 10–4 S cm–1. Finally, the PC nanocomposite electrolytes were tested in symmetrical lithium cells. Our findings suggest that all-polymer nanoparticles could represent a new building block material for solid-state lithium metal battery applications.

Design of Polymer Network and Li+ Solvation Enables Thermally and Oxidatively Stable, Mechanically Reliable, and Highly Conductive Polymer Gel Electrolyte for Lithium Batteries

Herein, we demonstrate that design of polymer network and Li+-ion solvation enables the fabrication of thermally and oxidatively stable, mechanically reliable, and highly conductive polymer gel electrolytes for lithium batteries. Polymer gel electrolytes have been used for Li-ion batteries (LIB) due to their quasi-solid natures and flexible shapes. However, they frequently suffer from the high vapor pressures of the incorporated solvents, low oxidative stabilities, and poor mechanical properties. To overcome these drawbacks, we fabricated a tough gel electrolyte comprising a tetra-arm poly(ethylene glycol) (TPEG) homogeneous polymer network, in which a tetraglyme(G4)-based solvate ionic liquid (SIL) was incorporated. It was intriguing to find that the solvation of Li+ ion by oxygen atoms (within G4 and TPEG), represented as [O]/[Li], governed the thermal and oxidative stabilities of the gel electrolyte, while the homogeneous network contributed to the mechanical reliability and high ionic conductivity. At [O]/[Li] = 5, the TPEG-based gel electrolyte with no free solvent simultaneously exhibited high thermal (>200 °C) and oxidative stabilities (>4.4 V), high stretchability, and high ionic conductivity (∼1 mS cm−1 at 30 °C). These favorable properties of the gel electrolyte resulted in reversible charge/discharge of a 4-V-class high-voltage cathode (LiNi0.6Mn0.2Co0.2O2, NMC622).

Sol-Gel coated WO3 thin films based complementary electrochromic smart windows

The WO3 films were prepared via sol- gel dip coating method. The optical, structural, morphological, electrochemical and electrochromic properties of the prepared films were studied. The WO3 film coated on glass substrate exhibits 74% transmission at 550 nm. XRD studies indicate the WO3 films in the amorphous state. FTIR spectrum confirms the formation of WO3. The FESEM image confirms the formation of smooth surface. The cyclic voltammetric study reveals the anodic/cathodic diffusion coefficients of 2.31/4.79 × 10−12 cm2/s for WO3 films. The film thickness was about 260 nm. The same film shows a change in optical transmission of 55.37% at 550 nm. The sol–gel coated WO3 films were used to develop the complementary electrochromic smart windows in conjugation with NiO and Ni0.95Co0.05O as an anode. A five layered EC windows were developed and studied with Li+ and H+ conducting gel electrolytes.

Flexible MoO2 Nanocrystals@N‐doped Carbon Nanofibers Film as a Self‐Supporting Anode for Quasi‐Solid‐State Sodium‐Ion Batteries

Herein, a bottom‐up electrospinning protocol is first developed to finely synthesize MoO2 nanocrystals@N‐doped carbon nanofibers (MoO2 NCs@N‐CNFs) film. The monodispersed MoO2 NCs of ≈2.1 nm in size are well confined in the 1D N‐CNFs. When evaluated as a self‐supporting anode for quasi‐solid‐state (QS) sodium‐ion batteries (SIBs) using the polyvinylidene fluoride hexafluoropropylene‐based Na+‐conducting gel electrolyte, the resultant MoO2 NCs@N‐CNFs exhibit remarkable Na+ storage behaviors in terms of reversible capacities and high‐rate cycling capabilities, benefiting from its synergistically structural and componential merits. More significantly, the contribution herein offers a simple yet efficient method to synthesize advanced hybrid anodes for QS SIBs.

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.

An efficient quasi-solid-state dye-sensitized solar cell with gradient polyaniline-graphene/PtNi tailored gel electrolyte

Quasi-solid-state dye-sensitized solar cells from polymer gel electrolytes are promising candidates to stabilize the photovoltaic performances. We demonstrate here the synthesis of a conducting gel electrolyte with gradient polyaniline-graphene/PtNi distribution and redox iodide/triiodide couples in a three-dimensional poly(acrylic acid)-poly(ethylene glycol) matrix. Through sandwiching poly(acrylic acid)-poly(ethylene glycol)/polyaniline-graphene/PtNi gel electrolyte with a dye-sensitized TiO2 photoanode and a PtNi counter electrode, the electrons flow from PtNi counter electrode to conducting gel electrolyte along gradient energy levels for reducing triiodide ions and shortening charge diffusion length. These gradient quasi-solid-state dye-sensitized solar cells achieve a maximized power conversion efficiency of 8.64% in comparison with 7.41% for the device with homogeneously distributed polyaniline-graphene/PtNi, not to mention 5.92% for poly(acrylic acid)-poly(ethylene glycol) tailored solar cell free of polyaniline-graphene/PtNi. Moreover, the optimized quasi-solid-state dye-sensitized solar cell presents a relatively high stability at room temperature over 10 days.

A facile random copolymer strategy to achieve highly conductive polymer gel electrolytes for electrochemical applications

A facile random copolymer strategy based on poly(styrene-ran-methyl methacrylate) (PS-r-PMMA) is proposed for the preparation of highly conductive and mechanically elastic solid-state gel electrolytes.

Highly uniform electrochromic tungsten oxide thin films deposited by e-beam evaporation for energy saving systems

In the last few decades, there has been a surge of interest in using tungsten oxide thin films as an active layer of electrochromic device. These devices have several practical applications such as smart window of buildings and automobile glazing for energy saving. The main objective of this work was to construct highly homogeneous and uniform e-beam evaporated amorphous WO3-x based films into electrochromic devices, which were fully characterized for switching speed, coloration efficiencies and cycling voltammetry responses. Fabricated devices contain indium doped transparent oxide coated glass as the transparent conductive electrode, ∼200 nm thickness of WO3-x as the cathodically coloring material and a lithium perchlorate based conducting gel electrolyte. X-ray diffraction patterns indicate that all as-deposited films are amorphous. Experimental results showed that both solid and liquid electrolyte electrochromic devices are initially very transparent that exhibit perfect optical modulation and coloration efficiency (up to 68.7 cm2/C and 52.6 cm2/C at 630 nm, respectively) due to easier intercalation of the Li+ within their structure. One of the more significant findings to emerge from this study is that e-beam coated electrochromic devices based on tungsten oxide thin films showed superior performance among to other coating methods. Therefore, excellent reversibility of color change behavior is attractive for pertinent use in electrochromic energy storage devices.

Characteristics of ionically conducting jatropha oil-based polyurethane acrylate gel electrolyte doped with potassium iodide

Abstract Currently, there is a growing trend of using bio-based materials from renewable resources in the construction of polymer electrolytes. In this study, a gel polymer electrolyte from Jatropha oil-based polyurethane acrylate (PUA) was prepared by doping the PUA with various concentrations (0–30 weight%) of potassium iodide (KI) salt. The PUA gel electrolyte was characterized by Fourier-transform infrared spectrometry (FTIR), thermal analysis and electrochemical analysis was performed by using electrochemical impedance spectroscopy. Subsequently, the dielectric properties of the gel polymer electrolyte were studied. A conductivity of 1.59 × 10−4 S cm−1 was achieved for the PUA incorporated with 25 weight% KI at room temperature. The dielectric study indicated the non-Debye nature of the materials. It has been shown, via transference number measurement that the conducting species in this work were predominantly ions, with only 4% contribution from electrons. An electrochemical stability window of 2.0 V was obtained by using linear sweep voltammetry for the highest conducting gel electrolyte.

A high-performance carbon-carbon(C/C) Quasi-Solid-State Supercapacitor with Conducting Gel Electrolyte

A high-performance carbon-carbon(C/C) Quasi-Solid-State Supercapacitor with Conducting Gel Electrolyte

Synthesis and optimization of new polymeric ionic liquid poly(diallydimethylammonium) bis(trifluoromethane sulfonyl)imde based gel electrolyte films

Polymeric ionic liquid-based gel electrolyte films are a new generation of electrolyte materials for flexible energy storage device applications. In this work, Li-ion conducting gel electrolyte films are prepared with the polymeric ionic liquid poly(diallydimethylammonium) bis(trifluoromethane sulfonyl)imide (poly(DADMATFSI)) as the host polymer and the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt as the dopant. The crystalline nature, thermal stability, ionic conductivity and electrochemical stability window of the polymeric electrolyte films are analyzed by various characterization techniques. It is found that the polymeric electrolyte films exhibit high flexibility and excellent thermal stability. Their room-temperature electrical conductivity increases with increasing LiTFSI concentration and reaches a high value of 1.00 × 10−3 S cm−1 at 20 wt% LiTFSI. The ionic transference numbers of the polymeric electrolyte films are in the range of 0.98–0.99, indicating that they are perfect ion conductors. Finally, the electrochemical stability window of the 20 wt% LiTFSI-doped polymeric electrolyte film is determined as approximately 6 V, which is a promising value for flexible energy storage device applications.

PEDOT and derivatives tailored conducting gel electrolytes for high-efficiency quasi-solid-state dye-sensitized solar cells

Conducting gel electrolytes are promising in improving long-term durability and power conversion efficiency of quasi-solid-state dye-sensitized solar cell (DSSC). We present here the synthesis of poly (3,4-ethylenedioxythiophene) (PEDOT), PEDOT-graphene complex and PEDOT-graphene/PtCo for robust conducting gel electrolytes. Arising from the enhanced electron concentration of PEDOT derivatives, the final gel electrolytes show superior catalytic activity toward redox I−/I3− couples. Upon illumination by simulated sunlight (air mass 1.5, 100 mW cm−2), the corresponding quasi-solid-state DSSC device yields a power conversion efficiency as high as 8.2% in comparison to 5.5% for PEDOT derivative-free solar cell. Moreover, these PEDOT and derivatives tailored photovoltaics are also featured with good stability over 15 days.

A series of conducting gel electrolytes for quasi-solid-state quantum dot-sensitized solar cells with boosted electron transfer processes

To pursue electron-generation stability with no sacrifice of photovoltaic performance has been a persistent objective for all kinds of solar cells. Here, we demonstrate the experimental realization of this objective by quasi-solid-state quantum dot-sensitized solar cells from a series of conducting gel electrolytes composed of polyacrylamide (PAAm) matrix and conductive polymers [polyaniline (PANi), polypyrrole (PPy) or polythiophene (PT)]. The reduction of Sx2− occurred in both interface and three dimensional framework of conducting gel electrolyte as a result of the electrical conduction of PANi, PPy and PT toward refluxed electrons from external circuit to Pt electrode. The resulting solar cells can yield the solar-to-electrical conversion efficiency of 2.33%, 2.25% and 1.80% for PANi, PPy and PT based gel electrolytes, respectively. Those solar cells possessed much higher efficiency than that of 1.74% based on pure PAAm gel electrolyte owing to the enhanced kinetics for Sx2− ↔ S2− conversion. More importantly, the stability of quasi-solid-state solar cell is significantly advanced, arising from the localization of liquid electrolyte into the three dimensional framework and therefore reduced leakage and volatilization.

High-efficiency platinum-free quasi-solid-state dye-sensitized solar cells from polyaniline (polypyrrole)-carbon nanotube complex tailored conducting gel electrolytes and counter electrodes

Polymer gel electrolytes having super catalytic behaviors and robust Pt-free counter electrodes (CEs) are promising for high-efficiency and cost-effective quasi-solid-state dye-sensitized solar cells (DSSCs). We present here the molecular design of polyaniline (polypyrrole)-graphene complex for conducting gel electrolytes and CEs, aiming at reducing their charge-transfer resistance and enhancing catalytic activity. The quasi-solid-stated DSSCs tailored with polyaniline-carbon nanotube and polypyrrole-carbon nanotube complexes yield maximized power conversion efficiencies of 8.23% and 7.69%, respectively. Arising from good encapsulation of three-dimension gel matrix, the photovoltaics are featured with relatively good long-term stability over 15 days. The high-efficiency and reasonable durability make so-called conducting gel electrolytes and Pt-free CEs promising in enhancing comprehensive properties of quasi-solid-state DSSC platforms.

Effect of organic solvent addition on electrochemical properties of ionic liquid based Na+ conducting gel electrolytes

A novel sodium ion conducting gel polymer electrolyte comprising room temperature ionic liquid, 1-ethyl 3-methyl imidazolium trifluoro-methane sulfonate (EMITf) incorporated with ethylene carbonate and propylene carbonate and its solution with sodium trifluoromethane sulfonate (NaTf) entrapped in poly(vinylidinefluoride-co-hexfluoropropylene) (PVdF-HFP) is prepared using solution cast technique. The gel electrolyte is obtained in the form of free-standing transparent film. The gel electrolyte offers electrical conductivity of ∼10−3Scm−1 at ∼30°C with good mechanical, thermal and electrochemical stability window. The electrical conductivity is measured as a function of temperature and found to be consistent with Vogel-Tamman-Fulcher (VTF) relationship in the temperature range from 30°C to 75°C.Sodium ion conduction in the gel electrolyte film is confirmed from cyclic voltammetry and transport number measurements. The value of the sodium ion transport number of the ionic liquid based gel electrolyte is ∼0.19. The sodium sulfur battery with the gel electrolytes delivers the first discharge capacity of 267mAhg−1 sulfur and then it decreases with repeated charge–discharge cycles.