Magnesium Ion Conducting Gel Polymer Research Articles

Plastic crystal-incorporated magnesium ion conducting gel polymer electrolyte for battery application

Studies on a novel composition of magnesium ion conducting gel polymer electrolyte (GPE), comprising a solution of Mg-salt, magnesium trifluoromethanesulfonate (Mg-triflate or \(\hbox {Mg(Tf)}_{2})\) in a plastic crystal succinonitrile (SN), entrapped in a host polymer poly(vinylidenefluoride–hexafluoropropylene) (PVdF–HFP) was reported. Small amount of an ionic liquid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMITf) was added to stabilize the GPE composition. The electrolyte possesses excellent dimensional integrity in the form of free-standing thick film, which offers the ionic conductivity of \(4 \times 10^{-3} \hbox { S } \hbox {cm}^{-1}\) at room temperature \({\sim }26{^{\circ }}\hbox {C}\). The electrochemical potential window of the electrolyte, observed from the linear sweep voltammetry, is determined to be \({\sim }4.1 \hbox { V}\). The magnesium ion conduction in the GPE film is confirmed from cyclic voltammetry, electrochemical impedance spectroscopy and dc polarization techniques. Different structural, thermal and electrochemical studies demonstrate the promising characteristics of the polymer film, suitable as electrolyte in rechargeable magnesium batteries. The potential of the GPE as electrolyte/separator was ascertained by fabricating a prototype magnesium battery of the configuration Mg:graphite composite \(\hbox {anode}/\hbox {GPE}/\hbox {MnO}_{2}\)-cathode. The specific discharge capacity of \(40 \hbox { mAh g}^{-1}\) (with respect to the \(\hbox {MnO}_{2}\) cathode material) was obtained at the first discharge. The cell shows charge–discharge performance for eight cycles with a substantial fading in capacity.

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.

Studies on the Effect of Nano-Sized MgO in Magnesium-Ion Conducting Gel Polymer Electrolyte for Rechargeable Magnesium Batteries

Magnesium-ion conducting gel polymer electrolytes (GPEs) with different contents of nano-sized MgO have been prepared and investigated by various electrical and electrochemical techniques. The Mg2+ ion conduction in GPEs was confirmed from cyclic voltammetry and impedance analysis. It was found that doping appropriate nano-sized MgO in the GPE can induce significant improvements in both the electrochemical and the mechanical properties of GPEs. The composite GPE with 7% MgO shows a high ionic conductivity of 4.6 × 10−3 S/cm with electrochemical stability up to 4.7 V versus Mg2+/Mg at room temperature. Furthermore, it is free-standing and flexible with high tensile strength (9.7 ± 0.1 MPa) and elongation at break (91.7 ± 0.2%), further ensuring their potential applications as GPEs for rechargeable Mg batteries.

Transport and Morphological Properties of Gel Polymer Electrolytes Containing Mg(CF<sub>3</sub>SO<sub>3</sub>)<sub>2</sub>

Magnesium-ion conducting gel polymer electrolytes (GPEs) based on PMMA with ethylene carbonate (EC) and propylene carbonate (PC) as a plasticizing solvent were prepared via the solution casting technique. Mg(CF3SO3)2 salt was used as source of magnesium ions, Mg2+. The variation of conductivity with salt concentrations, from 5 wt.% to 30 wt.% was studied. The gel polymer electrolyte with composition 20 wt.% of Mg(CF3SO3)2 exhibited the highest conductivity of 1.27 x 10-3 S cm-1 at room temperature. The conductivity-temperature dependence of gel polymer electrolyte films obeys Arrhenius behaviour with activation energy in the range of 0.18 eV to 0.26 eV. Ionic transport number was evaluated using DC polarization technique and it reveals the conducting species are predominantly ions. It is found that the ionic conductivity and transport properties of the prepared GPEs are consistent with the X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) studies.

Performance Studies of Activated Charcoal Based Electrical Double Layer Capacitors with Ionic Liquid Gel Polymer Electrolytes

Symmetric electrical double layer capacitors (EDLCs) with ionic liquid based magnesium ion conducting gel polymer electrolytes and activated charcoal (AC) electrodes have been constructed and characterized. Comparative studies have been performed employing three different electrolytes to fabricate EDLCs consisting of ionic liquid 1-ethyl-3-methyl-imidazolium trifluoromethanesulfonate (EMITf) or a solution of magnesium trifluoromethanesulfonate [Mg-triflate or Mg(Tf)2] in EMITf or solution of Mg-triflate in the mixture of EMITf and ethylene carbonate (EC)−propylene carbonate (PC) cosolvent, immobilized with poly(vinylidenefluoride−hexafluoropropylene) (PVdF−HFP) matrix. The performance characteristics of EDLCs based on impedance spectroscopy, cyclic voltammetry, and constant current charge−discharge technique are presented. The incorporation of magnesium salt and EC−PC cosolvent in gel polymer electrolytes play a significant role in the dramatic improvement of the EDLCs’ characteristics. The optimum capaci...

Magnesium ion-conducting gel polymer electrolytes dispersed with fumed silica for rechargeable magnesium battery application

Effect of fumed silica dispersion on poly(vinylidene fluoride-co-hexafluoropropylene)-based magnesium ion-conducting gel polymer electrolyte has been studied using various physical and electrochemical techniques. The composite gel electrolytes are free-standing and flexible films with enough mechanical strength. The optimized composition with 3 wt.% filler offers a maximum ionic conductivity of ∼1.1 × 10−2 S cm−1 at ∼25 °C with good thermal and electrochemical stabilities. The Mg2+ ion conduction in the gel nanocomposite film is confirmed from the cyclic voltammetry, impedance spectroscopy, and transport number measurements. The space-charge layers formed between filler particles and gel electrolyte are responsible for the enhancement in ionic conductivity. The applicability of the gel nanocomposite to a rechargeable battery is examined by fabricating a prototype cell consisting of Mg [or Mg-multiwalled carbon nanotube (MWCNT) composite] and MoO3 as negative and positive electrodes, respectively. The discharge capacity and the rechargeability of the cell have been improved when Mg metal is substituted by Mg-MWCNT composite. The discharge capacity of the optimized cell has found to be ∼175 mAh g−1 of MoO3 for an initial ten charge–discharge cycles.

Multiwalled Carbon Nanotube Electrodes for Electrical Double Layer Capacitors with Ionic Liquid Based Gel Polymer Electrolytes

Multiwalled carbon nanotube (MWCNT) based electrical double-layer capacitors (EDLCs) using ionic liquid incorporated magnesium ion conducting gel polymer electrolytes were constructed and characterized. For comparison, three electrolytes were used to fabricate EDLCs comprised of a room-temperature ionic liquid 1-ethyl-3-methyl-imidazolium trifluoromethanesulfonate (EMITf) or a solution of magnesium salt (magnesium trifluoromethanesulfonate or Mg triflate) in EMITf or a solution of magnesium salt in the mixture of EMITf and a cosolvent of ethylene carbonate (EC):propylene carbonate (PC), immobilized with poly(vinylidene fluoride-hexafluoropropylene). The comparative performance characteristics of the EDLCs based on impedance analysis, cyclic voltammetry, and galvanostatic charge–discharge tests for numerous cycles were presented. The role of magnesium ions and the EC:PC cosolvent incorporated in the gel electrolytes was important in the dramatic improvement of the EDLCs’ performance. The optimum capacitance value of (equivalent to the single electrode specific capacitance of of MWCNTs) was achieved for the EC:PC and the ionic liquid incorporated gel electrolyte based EDLCs. This corresponded to the specific energy of and the high value of power density of . The EDLCs showed excellent cyclic performances for or even more.

Magnesium ion-conducting gel polymer electrolytes dispersed with nanosized magnesium oxide

Abstract Experimental investigations are performed on novel magnesium ion-conducting gel polymer electrolyte nanocomposites based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), dispersed with nanosized magnesium oxide (MgO) particles. The nanocomposite materials are in the form of free-standing films. Various physical and electrochemical analyses demonstrate promising characteristics of these films, suitable as electrolytes in rechargeable magnesium batteries. The optimized material with 3 wt.% MgO offers a maximum electrical conductivity of ∼8 × 10−3 S cm−1 at room temperature (∼25 °C) with good thermal and electrochemical stabilities. The ion/filler–polymer interactions and possible conformational changes in host polymer PVdF-HFP due to the liquid electrolyte entrapment and dispersion of nanosized MgO are examined by Fourier transform infrared (FTIR), X-ray diffraction (XRD) and scanning electron microscopic (SEM) methods. The Mg2+ ion conduction in the gel film is confirmed from the cyclic voltammetry, impedance spectroscopy and transport number measurements. The Mg2+ ion transport number (t+) is enhanced substantially and found to have a maximum of ∼0.44 for the addition of 10 wt.% MgO nanoparticles. The enhancement in t+ is explained on the basis of the formation of space-charge regions due to the presence of MgO:Mg2+-like species, that supports Mg2+ ion motion.

Experimental investigations of an ionic-liquid-based, magnesium ion conducting, polymer gel electrolyte

Abstract Studies on a novel magnesium ion conducting gel polymer electrolyte based on a room temperature ionic liquid (RTIL) is reported. It comprises a Mg-salt, Mg(CF 3 SO 3 ) 2 [or magnesium triflate, Mg(Tf) 2 ] solution in an ionic liquid, 1-ethyl-3-methylimidazolium trifluoro-methanesulfonate (EMITf), immobilized with poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP), which is a freestanding, semitransparent and flexible film with excellent mechanical strength. Physical and electrochemical analyses demonstrate promising characteristics of these films, suitable as electrolytes in rechargeable magnesium batteries. The material offers a maximum electrical conductivity of ∼4.8 × 10 −3 S cm −1 at room temperature (20 °C) with excellent thermal and electrochemical stabilities. Possible conformational changes in the polymer host PVdF-HFP due to ionic liquid solution entrapment and ion–polymer interaction are investigated by Fourier transform infra-red (FTIR), X-ray diffraction (XRD) and scanning electron microscopic (SEM) methods. The Mg 2+ ion transport in the gel film is confirmed from cyclic voltammetry, impedance and transport number measurements. The Mg 2+ ion transport number ( t + ) is ∼0.26, which indicates a substantial contribution of triflate anion transport along with ionic conduction due to the component ions of the ionic liquid.

Preparation and characterization of gel polymer electrolytes for solid state magnesium batteries

Magnesium-ion conducting gel polymer electrolytes (GPE) were prepared and their electrochemical properties were characterized. The composition of GPE containing P(VdF- co-HFP), Mg(ClO 4) 2–EC/PC and SiO 2 was optimized in consideration of ionic conductivity and mechanical stability. Solid state magnesium cell employing magnesium anode, GPE, and vanadium oxide cathode was assembled and its cycling characteristics were investigated. The Mg/GPE/V 2O 5 cell showed low initial discharge capacity of 58 mAh/g based on active V 2O 5 material and poor cycling characteristics. At present, the results show that the Mg/GPE/V 2O 5 cell has an inferior cycling performance in comparison with that of well-developed, lithium metal polymer cells.