Properties Of Gel Polymer Electrolytes Research Articles

Tailoring the Properties of Gel Polymer Electrolytes for Sodium-Ion Batteries Using Ionic Liquids: A Review.

Ionic liquids are an extraordinary group of compounds, fully ionic in structure like inorganic salts but with low melting points, that resemble organic molecular solvents. Their chemical, electrochemical, and thermal stability is what draws the attention and enables their use in many applications, including electrochemical power sources. Even though they are no longer considered eco-friendly because of nonnegligible toxicity and long bioaccumulation, they can still be efficiently recovered, purified, and reused. These attributes can be harvested to enhance the properties of gel polymer electrolytes for the emerging sodium-ion batteries. The variety of anions and cations for ILs and their influence on the final properties of the compound opens the road to tuning the properties of gel polymer electrolytes. Ionic liquids as plasticizers constitute a major part of gel polymer electrolytes (average of 70 wt%) and hence, they affect the fundamental properties of gel electrolytes like ionic conductivity and electrochemical window. They also improve the safety features of sodium-ion batteries, which is relevant for their anticipated applications in stationary energy storage and electric vehicles. The presented review paper aims to explain the relationship between the cation and anion in ionic liquid and the properties of gel electrolytes for sodium-ion batteries.

Preparation and Properties of Gel Polymer Electrolytes with Li1.5Al0.5Ge1.5(PO4)3 and Li6.46La3Zr1.46Ta0.54O12 by UV Curing Process.

Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based gel polymer electrolytes (GPEs) are considered a promising electrolyte candidate for polymer lithium-ion batteries (LIBs) because of their free-standing shape, versatility, security, flexibility, lightweight, reliability, and so on. However, due to problems such as low ionic conductivity, PVDF-HFP can only be used on a small scale when used as a substrate alone. To overcome the above shortcomings, GPEs were designed and synthesized by a UV curing process by adding NASICON-type Li1.5Al0.5Ge1.5(PO4)3 (LAGP) and garnet-type Li6.46La3Zr1.46Ta0.54O12 (LLZTO) to PVDF-HFP. Experimentally, GPEs with 10% weight LLZTO in a PVDF-HFP matrix had an ionic conductivity of up to 3 × 10-4 S cm-1 at 25 °C. When assembled into LiFePO4/GPEs/Li batteries, a discharge-specific capacity of 81.5 mAh g-1 at a current density of 1 C and a capacity retention rate of 98.1% after 100 cycles at a current density of 0.2 C occurred. Therefore, GPEs added to LLZTO have a broad application prospect regarding rechargeable lithium-ion batteries.

Electrochemical Properties of Gel Polymer Electrolyte including Zinc Acetate Dihydrate for Zinc-Air Batteries

Electrochemical Properties of Gel Polymer Electrolyte including Zinc Acetate Dihydrate for Zinc-Air Batteries

Effect of varying lithium perchlorate salt concentration on electrochemical and physical properties of polymer gel electrolytes containing heat-resistant poly(methyl methacrylate) and succinonitrile

Effect of varying lithium perchlorate salt concentration on electrochemical and physical properties of polymer gel electrolytes containing heat-resistant poly(methyl methacrylate) and succinonitrile

Polymer Electrolytes for Stable and Safer Sodium-Based Batteries

Lithium-ion batteries (LIBs) have powered portable electronics and electric vehicles owing to their high energy density. In addition, the LIBs demand has significantly increased in the last years, raising concerns about the long-term availability and cost of the critical raw materials used in LIB production, e.g., cobalt, lithium, natural graphite, and copper [1,2]. In this scenario, alternative batteries must be developed based on low-cost and environmentally friendly raw materials. Sodium-ion batteries (SIBs) have become real energy storage devices for large-scale stationary applications and light electromobility due to the almost infinite and widely distributed sodium resources, the possibility to be made with environmentally friendly and sustainable raw materials, and lower cost.Liquid electrolytes are the electrolyte of choice for SIBs due to their high ionic conductivity, low viscosity, and good contact with electrodes. Nevertheless, they pose serious safety hazards due to their high volatility, flammability, severe decomposition reactions with the electrode, and risk of leakage. Therefore, alternative electrolytes must be explored for manufacturing safer SIBs. Polymer electrolytes are the best candidate to replace liquid electrolytes due to their higher thermal stability, wider electrochemical stability window, and less reactivity with the electrode. Nevertheless, their practical application is limited because they usually exhibit low ionic conductivity at room temperature and high interfacial resistance, which impoverish the performance of the sodium cells [3]. Adding plasticizers or inorganic fillers into the polymer is one way to enhanced ionic conductivity at room temperature. To keep the safety property of polymer electrolytes, ionic liquids (ILs) are more attractive plasticizers than carbonate-based solvents due to their non-volatility, non-flammability, wide electrochemical stability window, and high ionic conductivity, as well as thermal and chemical stability [4].This work describes, on the one hand, the physicochemical and electrochemical properties of gel polymer electrolytes using ILs as plasticizers. Their applicability has been demonstrated in sodium-metal cells using the P2-Na2/3Ni1/3Mn2/3O2 layered oxide as cathode material. The gel polymer electrolyte based-sodium-metal cell delivers a good specific capacity, with improved cycling stability of 99% and excellent Coulombic efficiency of 99.9% at room temperature, overcoming the electrochemical performance of the counterpart liquid electrolyte based-cell. On the other hand, a single sodium-ion conducting polymer based on bis(trifluoromethanesulfonyl)imide anionic center sodium salt monomer will be introduced. These results open the way for extending t sodium-based batteries’ long-term stability and safety without impoverishing the electrochemical performance.

Gel Polymer Electrolyte toward Large‐Scale Application of Aqueous Zinc Batteries

AbstractAqueous zinc batteries are promising candidates for energy storage and conversion devices in the “post‐lithium” era due to their high energy density, high safety, and low cost. The electrolyte plays an important role in zinc batteries by conducting and separating the positive and negative electrodes. However, the issues of zinc dendrites growth, corrosion, by‐product formation, hydrogen evolution and leakage, and evaporation of the aqueous electrolytes affect the commercialization of the batteries. Moreover, the widely used aqueous electrolytes result in large battery sizes, which are not conducive to the emerging smart devices. The intrinsic properties of gel polymer electrolytes (GPEs) can solve the above problems. In order to promote the wider application of GPEs‐based zinc batteries, in this review, the working principle and the current problems of zinc batteries are first introduced, andthe merits of GPEs compared to aqueous electrolytes are then summarized. Subsequently, a series of challenges and corresponding strategies faced by GPE is discussed, and an outlook for its future development is finally proposed.

A sandwich-structured ceramic-gel hybrid electrolyte to realize practical long cycle life Li-air batteries

Lithium-air batteries (LABs) have been regarded as the pinnacle of energy storage field owing to their ultrahigh energy density. However, most research focuses on lithium-oxygen batteries that work in pure oxygen instead of ambient air due to Li anode corrosion by the moisture in air atmosphere. Inspired by soft properties of gel polymer electrolyte (GPE) and dense structure characteristics of Li1.5Al0.5Ge1.5(PO4)3 ceramic, a sandwich-structured ceramic/gel hybrid electrolyte is successfully constructed via ultraviolet-irradiation method in this work, in which Li1.5Al0.5Ge1.5(PO4)3 ceramic is helpful in inhibiting Li anode corrosion while GPE is good at optimizing interface compatibility of electrolyte│electrode. The results show that the Li anode in LABs maintains metallic luster even after cycling in ambient air at 10–20% relative humidity (RH) for more than 100 h. Moreover, the interface resistance of Li symmetric cell is sharply reduced (from over 20 kΩ–1 kΩ), and it exhibits an ultralong lifespan (2000 h). Therefore, the lithium-air coin cell with this hybrid electrolyte has achieved more than 4-times the lifetime of that of conventional GPEs. A ‘3.5 cm × 3.5 cm’ pouch cell based on this hybrid electrolyte has also obtained an excellent cycle life of 750 h, further proving its application prospects in LABs.

Plasticizers and Salt Concentrations Effects on Polymer Gel Electrolytes Based on Poly (Methyl Methacrylate) for Electrochemical Applications.

This work describes the electrochemical properties of a type of PMMA-based gel polymer electrolytes (GPEs). The gel polymer electrolyte systems at a concentration of (20:80) % w/w were prepared from poly (methyl methacrylate), lithium perchlorate LiClO4 and single plasticizer propylene carbonate (PMMA-Li-PC) and a mixture of plasticizers made by propylene carbonate and ethylene carbonate in molar ratio 1:1, (PMMA-Li-PC-EC). Different salt concentrations (0.1 M, 0.5 M, 1 M, 2 M) were studied. The effect of different plasticizers (single and mixed) on the properties of gel polymer electrolytes were considered. The variation of conductivity versus salt concentration, thermal properties using DSC and TGA, anodic stability and FTIR spectroscopy were used in this study. The maximum ionic conductivity of σ = 0.031 S/cm were obtained for PMMA-Li-PC-EC with a salt concentration equal to 1 M. Ion-pairing phenomena and all ion associations were observed between lithium cations, plasticizers and host polymers through FTIR spectroscopy. The anodic stability of the PMMA-based gel polymer electrolytes was recorded up to 4 V. The glass temperatures of these electrolytes were estimated. We found they were dependent on the plasticization effect of plasticizers on the polymer chains and the increase of the salt concentration. Unexpectedly, it was determined that an unreacted PMMA monomer was present in the system, which appears to enhance ion conduction. The presence and possibly the addition of a monomer may be a technique for increasing ion conduction in other gel systems that warrants further study.

Electrical conduction of PMMA/PLA doped lithium bis(oxalato) borate based hybrid gel polymer electrolyte

The present work highlights the investigation of electrical conduction properties of gel polymer electrolyte (GPE) based poly(methyl) methacrylate (PMMA) and poly(lactic) acid (PLA) blend doped with various compositions of lithium bis(oxalato) borate. The impedance analysis revealed the GPE systems exhibit maximum ionic conductivity of 1.37 × 10−3 S cm−1 for sample PLi20. The electrical properties based on the dielectric permittivity of entire samples decreased with increasing frequency and followed the trend of ionic conductivity. Further analysis was carried out to determine the dielectric response at different temperatures, focusing on the most conducting sample (PLi20). Both dielectric constant and loss increase with the increasing temperature, which suggested that total polarization has occurred. In conclusion, the samples with 20 wt% composition of LiBOB exhibit the highest conducting properties which significantly provides good electrical performance for the application in energy storage devices.

Dielectric Study of Gel Polymer Electrolyte Based on PVA-K2CO3-SiO2

In this study, effect of filler (SiO2) on dielectric and electrical properties of gel polymer electrolyte (GPE) based on PVA-K2CO3 has been investigated and reported. The electrolyte were prepared by incorporating silica particle as a filler into the un-plasticized electrolyte (PVA-K2CO3). The prepared electrolyte were characterized physicochemically (FTIR) and electrochemically based on electrochemical impedance spectroscopy (EIS). Based on the impedance spectroscopy, complex permittivity (ε*) (dielectric constant and loss) and complex electrical modulus (M*) (real and imaginary modulus) were calculated. Characterization result indicate that SiO2 particles has successfully interacts with PVA-K2CO3 in the form of a three dimensional polymeric network. At low frequencies, high values of complex permittivity (dielectric constant and dielectric loss) were observed, which increased with increasing temperature, signifying an increase in ionic conductivity of the electrolyte. With the incorporation of filler, the peaks of both ε* and M* shifts towards higher frequency side suggesting the speed up the relaxation time. From the electrical modulus, the developed electrolyte is shown to be highly capacitive in nature. Based on the peak shape of the imaginary part of electric modulus, the non-Debye type relaxation predicted. Analysis of both dielectric permittivity and electrical modulus suggest that ionic and polymer segmental motions are strongly coupled. An optimum ionic conductivity of 3.25 × 104 mScm1 was achieved at ambient temperature at a composition of 15 wt.% SiO2 (PKS15).

Semiconductor TiO2 ceramic filler for safety-improved composite ionic liquid gel polymer electrolytes

Gel polymer electrolytes are one of the candidates for solid electrolytes to solve safety issues and improve the energy density of solid-state lithium batteries. Gel polymer electrolyte has high ionic conductivity at room temperature (~ 10−3 S cm−1), but its mechanical properties are poor. Herein, we prepared a series of composite gel polymer electrolytes by N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide, poly(vinylidene fluoride-hexafluoropropylene), LiTFSI, and various inorganic fillers. The addition of 5 wt% TiO2 can not only increase the ionic conductivity of gel polymer electrolytes but also improve the mechanical properties of gel polymer electrolytes. Besides, as a semiconductor, the TiO2 has safety risk when uses in composite gel polymer electrolyte. TiO2-ILGPE safety is investigated by cyclic voltammetry and battery performance. Additionally, TiO2-ILGPE displays a perfect flame-retarding ability, and TiO2 would not be reduced by the lithium metal anode.

Preparation of gel polymer electrolyte with high lithium ion transference number using GO as filler and application in lithium battery

High lithium ion transference number (tLi+) is one of the requirements of polymer electrolytes for utilization in lithium secondary batteries. Herein, graphene oxide (GO) is used as a filler to fabricate the homogeneous gel polymer electrolyte (GPE) for pursuing high tLi+. The effect of GO on the whole properties of gel polymer electrolytes including conductivity, lithium ion transference number, electrochemical window, electrochemical stability, and cycling performance are explored. Impressively, the GPE containing 0.3 wt% of GO (labeled as GPE-0.3%) demonstrates a high lithium ion transference number of 0.79 and improved electrochemical stability. The LFP/Li battery with GPE-0.3% as the separator shows excellent electrochemical cycle stability and Coulomb efficiency at 25 °C. The discharge specific capacity retention rate of this battery is 94.4% after 100 cycles at 0.2C. All these features make the gel polymer electrolyte useful as a separator of lithium metal batteries for high-performance lithium ion conductors, which exhibits high safety.

Electrochemical and Thermal Properties of Gel Polymer Electrolytes Modified by Flame Retardants

Flame retardants can solve a problem with flammability of electronic devices. This article deals with preparation of gel polymer electrolytes, which are used in lithium batteries, modified by flame retardants. Gel polymer electrolytes with selected additives, were prepared by different methods. Electrochemical and thermal properties were measured of all prepared gel polymer electrolytes.

Electrochemical Properties of Gel Polymer Electrolytes with Flame Retardant Used as Solvent

This paper deals with a method of preparation of gel polymer electrolytes modified by flame retardants. The method is characterized that as a solvent, one type of flame retardant is used here. Other components from basic chemical composition of a gel electrolyte didn’t change. The work is focused on measuring electrochemical and electrical properties of gel polymer electrolyte. Electrochemical properties were measured by linear voltammetry and impedance spectroscopy.

Enhanced Electrochemical Properties of Gel Polymer Electrolyte with Hybrid Copolymer of Organic Palygorskite and Methyl Methacrylate.

Gel polymer electrolyte (GPE) is widely considered as a promising safe lithium-ion battery material compared to conventional organic liquid electrolyte, which is linked to a greater risk of corrosive liquid leakage, spontaneous combustion, and explosion. GPE contains polymers, lithium salts, and liquid electrolyte, and inorganic nanoparticles are often used as fillers to improve electrochemical performance. However, such composite polymer electrolytes are usually prepared by means of blending, which can impact on the compatibility between the polymer and filler. In this study, the hybrid copolymer poly (organic palygorskite-co-methyl methacrylate) (poly(OPal-MMA)) is synthesized using organic palygorskite (OPal) and MMA as raw materials. The poly(OPal-MMA) gel electrolyte exhibits an ionic conductivity of 2.94 × 10−3 S/cm at 30 °C. The Li/poly(OPal-MMA) electrolyte/LiFePO4 cell shows a wide electrochemical window (approximately 4.7 V), high discharge capacity (146.36 mAh/g), and a low capacity-decay rate (0.02%/cycle).

Magnesium ion-conducting gel polymer electrolytes based on poly(vinylidene chloride-co-acrylonitrile) (PVdC-co-AN): a comparative study between magnesium trifluoromethanesulfonate (MgTf2) and magnesium bis(trifluoromethanesulfonimide) (Mg(TFSI)2)

In this paper, we report the effects of two different type of salts which are magnesium trifluoromethanesulfonate (MgTf2) and magnesium bis(trifluoromethanesulfonimide) (Mg(TFSI)2) on ionic conductivity studies, transference number measurements, and electrochemical properties of gel polymer electrolyte (GPE) systems. Both systems used poly(vinylidene chloride-co-acrylonitrile) (PVdC-co-AN) as the host polymer with the incorporation of plastic crystal succinonitrile (SN) and plasticizer ethylene carbonate (EC) in the ratio of (1:1). The system containing Mg(TFSI)2 exhibits higher in ionic conductivity of ~ (10−7–10−6) S cm−1 compared to the system containing MgTf2 of ~ (10−8–10−7) S cm−1. The conductivity temperature dependence studies of both GPE systems seem to obey the VTF relation. The ionic transference numbers were found to be > 0.9 for all GPEs while the highest cationic transference numbers obtained were 0.56 and 0.59 for MgTf2 system and Mg(TFSI)2 system, respectively. In linear sweep voltammetry (LSV) studies, wider electrochemical stability window was observed for the GPE containing Mg(TFSI)2 than that containing MgTf2 while cyclic voltammetry (CV) confirmed the conduction of Mg2+ ions in the GPEs. The structural and complex formations of the GPEs were confirmed by X-ray diffraction (XRD) analysis and both systems are shown to be amorphous in nature. The Mg/GPE/MgMn2O4 cells were assembled by using the most optimum GPE film from both systems and their charge-discharge performance was studied.

Effect of Cross-Linking Agents and Flame Retardants on Gel Polymer Electrolyte Properties

This article deals with research gel polymer electrolytes with the addition of various fire retardants and effect of crosslinking agents. The basic part of this article corresponds to the characteristics of the physical and electrochemical properties of gel polymer electrolytes, which depend on the type of crosslinking agent and on his concentrate in the sample electrolyte. Impedance spectroscopy and cyclic voltammetry were selected as measuring methods for electrical properties. The second part of this work corresponds how thermal properties of gel polymer electrolytes with addition of different flame retardants change.

Raising the softening temperature of poly(vinylidene fluoride) gel electrolytes

Factors affecting the softening temperature of polymer gel electrolytes (PGEs) made from poly(vinylidene fluoride) (PVDF) have been investigated. The melting temperature transition has been found to rise with increased polymer concentration and salt concentration but reduced by solvent dielectric constant. The solvent dielectric constant was reduced by mixing propylene carbonate (PC) with the non-solvent phenyl propanol (PhP). The use of lithium salt bis(oxalate)borate (LiBOB) in place of lithium tetrafluroborote (LiBF4) gives further enhancement to the softening temperature of PGEs. In all of those cases, there is an eventual trade-off between increased softening temperature and reduced ionic conductivity, in this fabricated gel electrolyte. Here, a variety of ways to tailor the properties of PGEs for different applications has been shown.

Insights on electrochemical properties of gel polymer electrolytes based on methylmethacrylate

This paper explains some properties of gel polymer electrolytes, which are mostly used in lithium ion batteries. An emphasis is laid on the internal structure and its influence on the mobility of ions in the substance. The ions are solvated and located randomly in the liquid base of the gel, and their movement is predominantly determined by the Stokes law for liquid electrolytes. Polymethylmethacrylate gel is used as a model substance here. This report is based on the experience of the authors and their associates.

Properties of gel polymer electrolytes based on poly(butyl acrylate) semi-interpenetrating polymeric networks toward Li-ion batteries

A new type of gel polymer electrolyte (GPE) based on poly(butyl acrylate) (PBA) semi-interpenetrating polymer networks (IPNs) and polyvinylidene fluoride (PVDF) was prepared in different molar ratios ranging from 1:0.5 to 1:1. A series of structure characterizations of PBA/PVDF had been measured using FTIR, XRD, and SEM. The electrolyte uptake test revealed that when the semi-IPNs were swollen with the commercial liquid electrolyte solutions, they showed an outstanding electrolyte uptake of 120% with a chemically cross-linked structure. All results indicated that the GPE exhibited the best performance when the molar ratio of BA and PVDF was 1:0.5. The prototype cell assembled with LiFePO4 as cathode, lithium metal as anode, and GPE as the electrolyte as well as separator retained 94% of its initial specific capacity after 100 charge-discharge cycles, showing an excellent cycling stability and a high electrochemical window (up to 4.5 V against Li+/Li) at room temperature. Compared with the liquid electrolyte, the GPE exhibited a similar stable cycling performance and was suitable for practical application in Li-ion batteries.