PMMA-based Gel Polymer Electrolytes Research Articles

An in-situ cross-linked network PMMA-based gel polymer electrolyte with excellent lithium storage performance

Gel polymer electrolytes (GPEs) effectively combine the advantages of high ionic conductivity and reduce the risk of leakage associated with liquid. In this study, a chemically cross-linked gel polymer electrolyte was prepared by in-situ polymerization using polymethyl methacrylate (PMMA) as a matrix and neopentyl glycol diacrylate (NPGDA) as cross-linking agent. The cross-linked structure of the GPE was preliminarily investigated, as well as the influence of the degree of cross-linking on its physical properties. The GPE exhibited a superior conductivity of 1.391 mS cm−1 at 25 °C. Herein, the Li|GPE|LiNi0.8Co0.1Mn0.1O2 cell has an excellent capacity retention rate of 80.7% after 150 cycles at 0.5 C in addition to a high discharge specific capacity of 203 mAh g−1. The structure of the cathode material is shielded from the production of byproducts during the charging and discharging of lithium-ion batteries by the cross-linked PMMA GPE.

PMMA-Based Composite Gel Polymer Electrolyte with Plastic Crystal Adopted for High-Performance Solid ECDs.

A PMMA-based gel polymer electrolyte (GPE) modified by a plastic crystal succinonitrile (SN) was synthesized using a facile solvent-casting method. The effects of SN additives upon lithium-ion dissociation and ionic conductivity were investigated primarily using Fourier transform infrared spectroscopy and electrochemical impedance spectroscopy, accompanied by other structural characterization methods. The results show that SN is distributed uniformly in the PMMA matrix with a high content and produces vast dipoles that benefit the dissociation of lithium salt. Hence, the SN-modified GPE (SN-GPE) achieves an excellent ionic conductivity of 2.02 mS·cm-1 and good mechanical properties. The quasi-solid-state ECD fabricated using the SN-GPE exhibits stable cyclability and excellent electrochromic performance, in which the bleaching/coloration response time is 10 s/30 s. These results add significant insight into understanding the inter- and intra-molecular interaction in SN-GPEs and provide a type of practicable high-performance GPE material for solid electrochromic devices.

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.

Composite gel-polymer electrolyte for high-loading polysulfide cathodes

The PMMA-based gel-polymer electrolyte (GPE) featuring the ester group (R–COO–R′) demonstrates high ionic conductivity and strong polysulfide retention for designing safe lithium–sulfur cells with high energy density.

PMMA-LiTFSI based gel polymer electrolyte for lithium-oxygen cell application

In this work, poly (methyl methacrylate), PMMA based gel polymer electrolytes (GPEs) have been studied. Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was selected as lithium-ion donor and tetraethylene glycol dimethyl ether (TEGDME) as a solvent. The highest conducting sample was obtained at 25 wt% LiTFSI with ionic conductivity value of 2.80 mS cm −1 . The dielectric constant of GPEs sample follows the conductivity trend. The percentage of free ions is observed to increase up to electrolyte containing 25 wt% LiTFSI salt. Beyond that, the free ions percentage decreased. Lithium-ion transference number for the highest conducting sample is 0.47. The highest ionic conducting sample show good electrode-electrolyte interfacial stability and is suggested suitable in lithium-oxygen batteries. The charge and discharge capacities in the first cycle were 0.87 and 1.23 mAh cm −2 , respectively. Formation of Li 2 O 2 can be observed by XRD pattern of the air cathode during the discharge. • Large anion size contributes to enhance the ionic conductivity and lithium transference number. • A gel polymer electrolyte based on PMMA is a viable candidate for use as the electrolyte in a lithium-oxygen battery. • The discharge capacity retention of lithium-oxygen cell is 26 % after five cycles.

Effect of PC:DEC plasticizers on structural and electrical properties of PVDF–HFP:PMMA based gel polymer electrolyte system

A gel polymer electrolyte based on poly(vinylidene fluoride–hexafluoropropylene) (PVDF–HFP) and poly(methyl methacrylate) (PMMA) as host polymers, lithium perchlorate ( $${\hbox {LiClO}}_{{4}}$$ ) as salt has been prepared with different concentrations of mixture of propylene carbonate (PC) and diethyl carbonate (DEC) (1:1) as plasticizers by using solution casting technique. Changes in structural properties have been studied by X-ray diffraction. Surface morphology has been analyzed using atomic force microscope studies. Electrical conductivity has been carried out by electrochemical impedance spectroscopy in the temperature range 303 K to 343 K. Addition of plasticizers to polymer blend electrolyte has been found to result in an enhancement of the ionic conductivity. A maximum electrical conductivity of $$1.03 \times 10^{-3}$$ S cm $$^{-1}$$ at 303 K has been achieved for the polymer blend gel electrolyte containing 60 wt $$\%$$ of PC:DEC plasticizers. The temperature dependence of the ionic conductivity exhibits Vogel–Tammann–Fulcher type behavior indicating a strong coupling between the ionic conductivity and the polymer chain segmental motions. AC conductivity has been analyzed using Jonscher’s power law. A relaxation phenomenon is studied with modulus formalism.

Improved lithium ion dynamics in crosslinked PMMA gel polymer electrolyte.

Since PMMA-based gel polymer electrolytes could substitute PVDF-HFP based gels currently used in Li-ion batteries at lower financial and environmental costs, we investigate here the solvation and transport properties of the lithium ions in a crosslinked PMMA-based gel polymer electrolyte by a combination of thermal and electrochemical methods, Raman spectroscopy, pulse field gradient (PFG) and electrophoretic NMR (eNMR) techniques, as well as ab initio calculations. The conductivity of the gel containing 10 wt% polymer is only reduced by 14% relative to the liquid electrolyte. In addition, the co-solvation by polymer functional groups, a priori expected to slow lithium transport relatively to the anion, has instead a positive effect on lithium transport. Indeed, the ester groups not only participate in lithium solvation and increase ionic dissociation, but since this interaction is rather weak, rather than lowering the lithium diffusion relatively to other species, it mainly decorrelates lithium transport from anionic mobility. Compared to its liquid fraction, the gels show, at the same time, better dissociation and a higher lithium transference number, which results in a higher cationic conductivity, despite the overall conductivity loss.

Ionic conductivity of a PMMA based gel polymer electrolyte and its performance in solid state electrochemical cells

Official journal of the Institute of Physics - Sri Lanka. Full text articles are available. The journal also has a website at http://www.ip-sl.org/sljp/The new email for the Editor is eic.ipsl@gmail.com.

Ionic Transport and Electrochemical Properties of PMMA-Based Gel Polymer Electrolytes for Magnesium Batteries

Poly (methyl) methacrylate (PMMA)-based gel polymer electrolytes (GPEs) containing magnesium triflate, Mg (CF3SO3)2 salt were prepared using solution casting technique. Different concentrations of Mg (CF3SO3)2 ranging from 5 wt.% to 30 wt.% have been added into a mixture of ethylene carbonate (EC) and propylene carbonate (PC) with a fixed mass ratio of 2:1. These free-standing GPE films were characterized using electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV) and cyclic voltammetry (CV). The highest ionic conductivity of 1.27 x 10-3 S cm-1 is obtained from the GPE film containing 20 wt.% of Mg (CF3SO3)2 salt. The electrochemical window stability has been found in the range of-2.5 V to 2.5 V for the highest conducting GPE film. This value is considerably high enough for the GPE film to be used as electrolyte in magnesium rechargeable batteries.

Comparison Studies of Blend and Unblend GPE Systems: Ionic Conductivity, Structural and Morphological Properties

Studies on comparison of blend and unblend PMMA-based gel polymer electrolytes containing LiClO4salt with EC and PC as plasticizing solvent is reported. The GPE samples are prepared by varying the salt concentrations from 5 wt.% to 30 wt.%. At room temperature, PVdF-HFP/PMMA blend GPE exhibits the highest conductivity of 4.71 x 10-3S cm-1containing 25 wt.% of LiClO4salt while the highest conductivity for unblend GPE is 3.34 x10-3S cm-1containing 20 wt.% of LiClO4salt. The amorphous nature and morphological properties between LiClO4salt, EC and PC in the blend and unblend GPE systems have been validated using XRD and FESEM analysis.

Characterization of Plasticized PMMA-LiClO<sub>4</sub> Solid Polymer Electrolytes

In the present work, the effect of Li salt i.e. LiClO4 contained in composite plasticizer (PC+DEC) with three different concentrations on ionic transport and other electrochemical properties of PMMA based gel polymer electrolytes synthesized has been investigated. The electrolytes have been synthesized by solution casting technique by varying the wt (%) of salt and plasticizer. The formation of polymer-salt complexes and their structural characterization have been carried out by FTIR spectroscopic and XRD analyses. The room temperature ionic conductivity of the electrolyte composition 0.6PMMA-0.125(PC+DEC)-0.15LiClO4 (wt %) has been found to be maximum whose magnitude is 0.40×10-5 S/cm as determined by ac impedance analysis. The temperature dependent ionic conductivity of electrolyte sample0.6PMMA-0.125(PC+DEC)-0.15LiClO4 has further been investigated. Thermal analyses of electrolyte samples of all three compositions have also been done.

Electrical double layer capacitor using poly(methyl methacrylate)–C4BO8Li gel polymer electrolyte and carbonaceous material from shells of mata kucing (Dimocarpus longan) fruit

Poly(methyl methacrylate), PMMA based gel polymer electrolytes (GPE) containing immobilized lithium bis(oxalato)borate, C4BO8Li or LiBOB dissolved in a propylene carbonate–ethylene carbonate binary solvent were prepared by heating the cast solution between 70 and 80°C for 20min. The electrolyte composition with 5wt.% PMMA exhibited the highest conductivity of 3.27 and 7.46mScm−1 at 298 and 343K respectively. Cyclic voltammetry studies on the GPE containing 15wt.% PMMA and 85wt.% (0.6M LiBOB) dissolved in equal weight of ethylene and propylene carbonates showed that the electrochemical potential stability window of the electrolyte lies in the range between −1.7 to +1.7V. Linear sweep voltammetry indicates the gel polymer electrolyte is stable up to 1.7V. The electrical double layer capacitor (EDLC) using the highest conducting GPE and activated carbon derived from shells of the mata kucing (Dimocarpus longan) fruit has capacitance of ∼685mFg−1 on the first cycle. The EDLC performance was also characterized using cyclic voltammetry and charge–discharge processes at constant current.

Enhanced ionic conductivity in novel nanocomposite gel polymer electrolyte based on intercalation of PMMA into layered LiV3O8

In the present work, a novel polymer electrolyte based on poly(methyl methacrylate) (PMMA)/layered lithium trivanadate (LiV3O8) nanocomposite has been investigated. X-ray diffraction (XRD) study shows that d-spacing is increased from 6.3 ± 0.1 A to 12.8 ± 0.1 A upon intercalation of the polymer into the layered LiV3O8. Room temperature ionic conductivity of the obtained nanocomposite gel polymer electrolyte is found to be superior to that of conventional PMMA-based gel polymer electrolyte. Enhancement in ionic conductivity of the nanocomposite gel electrolyte is attributed to the formation of a two-dimensional channel as a result of decreased interaction between Li+ and V3O8− layers as confirmed by FTIR. SEM results show aggregation of nanocomposite particles resulting from extension of some of the polymer chains from interlayer to the edge providing paths for Li+ ion transport. Interfacial stability of nanocomposite gel electrolyte is also found to be better than that of the conventional PMMA-based gel polymer electrolyte.

Investigations on EDLCs using PMMA-based Gel Polymer Electrolytes

Investigations on EDLCs using PMMA-based Gel Polymer Electrolytes

Cycling and at-rest stabilities of a complementary electrochromic device containing poly(3,4-ethylenedioxythiophene) and Prussian blue

Abstract PEDOT-based electrochromic devices (ECDs) have been investigated intensively in recent years. In order to obtain an ECD having long cycle life, the counter electrode and electrolyte used should be compatible in the electrochemical environment. Prussian blue (PB) is proven to be electrochemically stable when cycling in non-aqueous solutions. Thus a new organic-inorganic complementary ECD was assembled in combination with a PMMA-based gel polymer electrolyte. This ECD exhibited deep blue-violet when applying −2.1 V and became light blue when applying 0.6 V. Under these conditions, the transmittance of the ECD at 590 nm changed from 13.8% (−2.1 V) to 60.5% (+0.6 V) with a coloration efficiency of 338 cm2/C. The cell retained 55% of its maximum transmittance window ( Δ T max ) after 50,640 repeated cycles. Moreover, the at-rest stability test revealed a transmittance window ( Δ T ) decay of 9.6% over a period of 107 days. Therefore, the proposed PEDOT-PB ECD may have potential for practical applications.

Preparation of rechargeable lithium batteries with poly(methyl methacrylate) based gel polymer electrolyte by in situ?-ray irradiation-induced polymerization

An admixture of commercial liquid electrolyte (LB302, 1 M solution of LiPF6 in 1:1 EC/DEC) and methyl methacrylate (MMA) was enclosed in CR2032 cells. The assembled cells were then γ-ray-irradiated using configurations of half cells and full cells. Through this in situ irradiation polymerization process, we obtained rechargeable lithium ion cells with poly(methyl methacrylate) (PMMA) based gel polymer electrolytes (GPE). Galvanostatic cycling, AC impedance spectroscopy, and cyclic voltammetry were employed to investigate the electrochemical properties of the cells and the gel polymer electrolyte. This PMMA-based gel polymer electrolyte was found to exhibit a high ionic conductivity (at least 10−3 S cm−1) at room temperature. Due to a significant increase in the charge transfer resistance between the GPE and the cathode, the cell impedance of a PMMA-based lithium ion cell is greater than that of a liquid-electrolyte-based cell. The discharge capacity of a LiNi0.8Co0.2O2/GPE/graphite is approximately 145 mAh g−1 for the first cycle and decreases to123 mAh g−1 after 20 cycles. In addition, a large initial cell impedance (LICI) was observed in the irradiated positive half cell. In this paper, we propose a possible mechanism related to the detachment of the PMMA layer from the lithium electrode. This detachment of the PMMA layer from the lithium electrode has not been explicitly discussed previously.

Spectroscopic and electrochemical studies of PMMA-based gel polymer electrolytes modified with interpenetrating networks

This work reports the mechanical strength and ionic conductivity of poly(methyl methacrylate) (PMMA)-based polymer gel electrolytes that are modified with interpenetrating networks. A series of poly(ethylene glycol dimethacrylate) (PEGDMA) polymers with different numbers of repeating ethylene oxide units is utilized as the network former. The mechanical strength of the electrolytes is estimated from their stress–strain curves. To assess ionic distribution in the gel electrolytes, an analysis is made of the infrared absorption bands of the symmetric stretching modes of SO 3 in triflate anions that are incorporated as the lithium salt. The local viscosity around charge-carrying ions is estimated by means of the fluorescence depolarization method. Introduction of a PEGDMA network, in particular by modifying with lower molecular weight PEGDMA, is effective for increasing the mechanical strength of PMMA-based gel electrolytes. This feature can be explained by a cross-linking effect provided by the network former. In addition, the PEGDMA modification leads to an increase in ionic conductivity due to enhancement in both the free-ion fraction and the ionic mobility. This favorable feature probably results from the introduction of the ethylene oxide unit (as PEGDMA) which has a high donor number for Li + ions and high chain flexibility. Consequently, the use of higher molecular weight PEGDMA is advantageous for conductivity enhancement.

Long-term structural stability of PMMA-based gel polymer electrolytes

Gel-based SPEs are promising candidates as polymer electrolytes in electrochemical devices such as Li-ion batteries. In particular, PMMA-based gel electrolytes have shown electrical conductivity at room temperature as high as 10 −3 Scm −1. One of the most important drawbacks of these gels is their lack of long-term structural stability, which determines a reduction of the contact area with the electrode and causes drops in conductance. We have observed macroscopic volume reductions (>5%) in gels made of PMMA, ethylene carbonate (EC), dimethyl carbonate (DMC) and LiN(CF 3SO 2) 2. The timescale of this phenomenon depends on the ratio EC/DMC. In this paper we investigate the structural modifications induced in the above mentioned system by annealing for several months at room temperature. We show that a crystalline phase grows in a matter of weeks with a kinetics controlled by the ratio EC/DMC and disappears for longer annealings.