Stable Gel Polymer Electrolyte Research Articles

A polysaccharide extracted from guar beans-based gel polymer electrolytes for efficient dye-sensitized solar cells

Liquid electrolytes in dye-sensitized solar cells (DSSCs), while effective in minimizing recombination of TiO2 conduction band with redox couple (I−/I3−), suffer from leakage and evaporation issues, hindering commercialization. Although solid-state electrolytes were introduced as an alternative, their performance is constrained by poor electrode contact. To solve these issues, gel polymer electrolytes (GPE) have been formulated based on guar gum (GG) crosslinked with poly (ethylene glycol) (PEG 200) incorporating potassium iodide (KI) as the doping salt. The incorporation of PEG 200 into the GPE allows a stable gel polymer electrolyte to form by using dimethyl sulfoxide (DMSO) as the organic solvent. The GPE boasts a structure free from leakage, showcases captivating ionic conductivity and thermal stability. Comprehensive structural and thermal analyses, including Fourier Transform Infrared spectroscopy (FTIR), Differential Scanning Calorimeter (DSC), and Thermogravimetric Analysis (TGA) have been carried out. The electrochemical properties of the GPE were also studied via Electrical Impedance Spectroscopy (EIS) and are significantly enhanced with higher concentration of KI introduced into the GPE. The highest ionic conductivity (σ) value of 9.76 × 10−3 S cm−1 is obtained in the GPE contained 40 wt% KI, with an efficiency of 5.65 %. Importantly, this study introduces a better and effective approach for designing electrolyte materials with high ionic conductivity, efficiency, and stability in DSSC.

A two-step strategy for constructing stable gel polymer electrolyte interfaces for long-life cycle lithium metal batteries

Due to the high reactivity between the lithium metal and traditional organic liquid electrolyte, the reaction of lithium metal electrode is usually uneven and there are also unexpected side reactions. Therefore, construction of a stable solid electrolyte interface (SEI) is highly essential to improve the performance of lithium metal anode. Herein, a sandwich-like gel polymer electrolyte (GPE) is accurately prepared by in-situ polymerization of Polyacrylonitrile (PAN) nanofiber membrane with trihydroxymethylpropyl trimethylacrylate (TMPTMA) and 1,6-hexanediol diacrylate (HDDA). The resulting GPE with a tightly cross-linked gel skeleton exhibits high ionic conductivity and electrochemical window of 5.6 V versus Li/Li+. In particular, the pretreatment of Li metal anode can improve the interfacial wettability, and the synergy of the chemically pretreated Li metal anode surface and the GPE can electrochemically in situ generate SEI with compositionally stable and fluorine-rich inorganic components. Owing to these unique advantages, the interfacial compatibility between the GPE and lithium metal is greatly improved. Meanwhile, the formed SEI can inhibit the formation of lithium dendrites, and decomposition of GPE would be alleviated. The assembled Li-FEC|GPE|LiFePO4 full cell shows a high initial discharge capacity of 157.1 mA h g−1, and maintains a capacity retention of 92.3% after 100 cycles at 0.2C.

A high thermally stable polyacrylonitrile (PAN)-based gel polymer electrolyte for rechargeable Mg-ion battery

The ionic conductivity and thermal stability of the electrolyte-separator system is an essential parameter for improving battery performance and safety. The present work addresses the high thermally stable gel polymer electrolyte (GPE) using polyacrylonitrile (PAN) as a polymer membrane and magnesium perchlorate in propylene carbonate (Mg(ClO4)2-PC) as a liquid electrolyte. The PAN based polymer membrane is prepared by electrospinning process which produces a bead free and uniformly distributed nanofibers. The electrospun PAN based GPE is characterized by different physical and electrochemical techniques like X-ray diffraction, field emission scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, ionic conductivity, linear sweep voltammetry, magnesium ion transference number and electrochemical impedance spectroscopy. The ionic conductivity of PAN is 3.28 mS cm−1, compared to that of PP Celgard is 1.97 × 10–4 mS cm−1 at 30 °C. The electrochemical stability of PAN is 4.6 V and also exhibits excellent interfacial stability with magnesium metal. The results showed that the PAN-based GPE has higher ionic conductivity and thermal stability than the polypropylene (PP) Celgard membrane.

Studies of Ionogel Structure and its Electronic and Optical Characterization by ONIOM and other Hybrid Computational Approaches

Gel polymer electrolytes (GPE) are emerging as imperative materials for applications in electrochemical devices. Now a day, ionic liquids are generally, incorporated in polymer matrices giving rise to an interesting class of materials ‘Ionogels’. Here, a computational approach is utilized to study the structural properties of an ionogel, which demonstrates the doping of ionic liquid in the polymethyl methacrylate polymer lattice. Here, Our own N-layered Integrated sub-atomic Orbital and sub-atomic Mechanics (ONIOM) were utilized for computation and to anticipate the conduct of 1-Butyl-1-methylpyrrolidinium bis(trifluoromethyl sulfonyl) imide in PMMA. The hypothetical review uncovered that the ionogel is sufficiently hard to shape a thermally stable gel polymer electrolyte.

Electrical studies on ionic liquid-based gel polymer electrolyte for its application in EDLCs

Ionic liquid-based gel polymer electrolyte (GPE) has been synthesized using standard solution cast technique. Different weight percent of ionic liquid, 1-Butyl-3-methylimidazolium chloride (BMIMCl) and liquid electrolyte, ethylene carbonate (EC)–propylene carbonate (PC)–tetra ethyl ammonium tetra fluoro borate (TEABF4) was incorporated in polymer, poly(vinylidene fluoride-co-hexafluoro propylene (PVdF-HFP) to obtain mechanically stable gel polymer electrolyte film (GPE) having maximum conductivity of ~10−3 S cm−1 at room temperature, which is acceptable from device fabrication point of view. Potential window and ionic transference number has been obtained to examine the potential limit and ionic characteristics of optimized GPE system. Temperature dependence behavior of electrical conductivity curve follows Arrhenius nature in the temperature range of 303–373 K. Pattern of dielectric constant and its loss as a function of frequency and temperature have been studied and is being explained on the basis of electrode interfacial polarization effect. Frequency-dependent conductivity spectra obey the Jonscher’s power law. Further, optimized composition of GPE has been tested successfully for its application in supercapacitor fabrication with activated charcoal as an electrode material. Maximum specific capacitance of 118.6 mF cm−2 equivalent to single electrode specific capacitance of 61.7 F g−1 have been observed for the optimized GPE film.

Preparation and characterization of PAN–KI complexed gel polymer electrolytes for solid-state battery applications

The free standing and dimensionally stable gel polymer electrolyte films of polyacrylonitrile (PAN): potassium iodide (KI) of different compositions, using ethylene carbonate as a plasticizer and dimethyl formamide as solvent, are prepared by adopting ‘solution casting technique’ and these films are examined for their conductivities. The structural, miscibility and the chemical rapport between PAN and KI are investigated using X-ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry methods. The conductivity is enhanced with the increase in KI concentration and temperature. The maximum conductivity at 30°C is found to be 2.089 × 10−5 S cm−1 for PAN:KI (70:30) wt%, which is nine orders greater than that of pure PAN (< 10−14 S cm−1). The conductivity-temperature dependence of these polymer electrolyte films obeys Arrhenius behaviour with activation energy ranging from 0.358 to 0.478 eV. The conducting carriers of charge transport in these polymer electrolyte films are identified by Wagner’s polarization technique and it is found that the charge transport is predominantly due to ions. The better conducting sample is used to fabricate the battery with configuration K/PAN + KI/I2+ C + electrolyte and good discharge characteristics of battery are observed.

Electrical Studies of Gel Polymer Electrolyte based on PAN for Electrochemical Cell Applications

The free standing and dimensionally stable Gel Polymer electrolyte films of PAN: KI of varying compositions using Ethylene carbonate (EC) as a plasticizer and dimethyl formamide (DMF) as solvent are prepared by adopting ‘solution casting technique’ and these films are probed for their conductivities. The miscibility and the chemical rapport between PAN and KI are investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) methods. The conductivity is increased with the increase of KI concentration as well as temperature. The maximum conductivity at 30 oC is found to be 2.089 X 10-5 Scm-1 for PAN:KI (70:30) wt.% which is nine orders greater than that of pure PAN (<10-14 S cm-1). The conductivity-temperature dependence of these polymer electrolyte films obeys Arrhenius behaviour with activation energy ranging from 0.358eV to 0.478eV. The conducting carriers of charge transport in these polymer electrolyte films are identified by Wagner's polarization technique and it is found that the charge transport is predominantly due to ions. The highest conducting sample is used to fabricate the battery with configuration K/ PAN+KI /I2+C+electrolyte and good discharge characteristics of battery are observed.

Novel Stable Gel Polymer Electrolyte: Toward a High Safety and Long Life Li-Air Battery.

Nonaqueous Li-air battery, as a promising electrochemical energy storage device, has attracted substantial interest, while the safety issues derived from the intrinsic instability of organic liquid electrolytes may become a possible bottleneck for the future application of Li-air battery. Herein, through elaborate design, a novel stable composite gel polymer electrolyte is first proposed and explored for Li-air battery. By use of the composite gel polymer electrolyte, the Li-air polymer batteries composed of a lithium foil anode and Super P cathode are assembled and operated in ambient air and their cycling performance is evaluated. The batteries exhibit enhanced cycling stability and safety, where 100 cycles are achieved in ambient air at room temperature. The feasibility study demonstrates that the gel polymer electrolyte-based polymer Li-air battery is highly advantageous and could be used as a useful alternative strategy for the development of Li-air battery upon further application.

Cycling performance of lithium polymer cells assembled by in situ polymerization of a non-flammable ionic liquid monomer

Lithium polymer cells composed of a lithium negative electrode and a LiCoO2 positive electrode were assembled with a gel polymer electrolyte obtained by in situ polymerization of an electrolyte solution containing an ionic liquid monomer with vinyl groups. The polymerization of the electrolyte solution containing the non-flammable ionic liquid monomer resulted in a significant reduction of the flammability of the gel polymer electrolytes. The lithium polymer cell assembled with the stable gel polymer electrolyte delivered a discharge capacity of 134.3mAhg−1 at ambient temperature and exhibited good capacity retention.

Poly(vinylpyridine- co-styrene) based in situ cross-linked gel polymer electrolyte for lithium-ion polymer batteries

A gel polymer electrolyte (GPE) was successfully prepared by means of an in situ cross-linking reaction of poly(2-vinylpyridine-co-styrene) and oligo(ethylene oxide) with epoxide functional groups at 65 °C without using a polymerization initiator. A stable gel polymer electrolyte could be obtained by adding only 1% of a polymer gelator. The ionic conductivity of the GPE containing 99 wt% of liquid electrolyte was measured to be ca. 10 −2 S/cm at the ambient temperature. The ionic conductivity of the resulting GPE was comparable to that of a pure liquid electrolyte. The electrochemical stability window of the prepared gel polymer electrolytes was measured to be 5.2 V. The test cell carried a discharge capacity of 133.2 mAh/g at 0.1 C and showed good cycling performance with negligible capacity fading after the 200th cycle, maintaining 99.5% coulombic efficiency throughout 200 cycles. The resulting gel polymer electrolyte prepared by in situ thermal cross-linking without a polymerization initiator holds promise for application to on the high power lithium-ion polymer batteries.

과불소화된 아크릴레이트 가교제로 제조된 직접 가교형 겔 고분자 전해질의 전기화학적 특성

본 연구에서는 organophosphate를 기반으로 한 과불소화된 아크릴레이트 가교제를 사용하여 제조한겔 고분자 전해질의 이온 전도도 및 전기화학적 특성을 평가하였다. 과불소화된 아크릴레이트 가교제를 사용하여 만든 겔 고분자 전해질은 액체전해질의 함량이 최대 97 wt%까지 안정한 겔 상태를 유지하였다. 본 연구에서 제조한 겔 고분자 전해질의 이온전도도는 <TEX>$30^{\circ}C$</TEX>에서 <TEX>$1.0\;{\times}\;10^{-2}\;S/cm$</TEX>의 값을 가졌다. 또한 전기화학적 안정성 테스트에서도 약 4.5V로 이상까지 산화에 의한 열화가 없이 안정하였다. 합성된 겔고분자 전해질을 리튬이온 고분자 전지에 적용하여 그 활용성을 평가하였다. 양극으로는 <TEX>$LiCoO_2$</TEX>를 사용하였으며 음극으로는 카본을 사용하였다. 이렇게 만든 리튬이온 고분자 전지는 0.1C에서 136.11 mAh/g의 용량으로 이론용량과 거의 비슷한 값을 나타내었으며, 2C 방전에서도 초기 용량의 91%를 유지하였다. 또한 500번의 충방전 후에도 초기 용량의 70%정도의 용량을 유지하였다. The gel polymer electrolyte(GPE) were prepared by in-situ thermal cross-linking reaction of homogeneous precursor solution of perfluorinated phosphate-based cross-linker and liquid electrolyte. Ionic conductivities and electrochemical properties of the prepared gel polymer electrolyte with the various contents of liquid electrolytes and perfluorinated organophosphate-based cross-linker were examined. The stable gel polymer electrolyte was obtained up to 97 wt% of the liquid electrolyte. Ionic conductivity and electrochemical properties of the gel polymer electrolytes with the various chain length of perfluorinated ethylene oxide and different content of liquid electrolytes were examined. The maximum ionic conductivity of liquid electrolyte was measured to be <TEX>$1.02\;{\times}\;10^{-2}\;S/cm$</TEX> at <TEX>$30^{\circ}C$</TEX> using the cross-linker(<TEX>$PFT_nGA$</TEX>). The electrochemical stability of the gel polymer electrolyte was extended to 4.5 V. The electrochemical performances of test cells composed of the resulting gel polymer electrolyte were also studied to evaluate the applicability on the lithium polymer batteries. The test cell carried a discharge capacity of 136.11mAh/g at 0.1C. The discharge capacity was measured to be 91% at 2C rate. The discharge capacity decreased with increase of discharge rate which was due to the polarization. After 500th charge/discharge cycles, the capacity of battery decreased to be 70% of the initial capacity.