Doped Polymer Electrolyte Research Articles

Synthesis of base-acid pair based poly(isatin arylene) membranes for HT-PEMFC applications

Phosphoric acid (PA) doped polymer electrolyte membranes are promising high temperature proton exchange membranes (HT-PEMs) for fuel cells. While PA doped polybenzimidazole (PBI) has been considered as a successful HT-PEM, several issues remain, such as the use of carcinogenic monomer, poor solubility in organic solvents and easy PA loss. To develop more cost-effective, readily synthesized and high-performance HT-PEMs, this study focuses on synthesizing high-performance HT-PEMs based on poly(isatin arylene)s (i.e., PIT and PIB) containing a lactam structure and devoid of ether bonds. These polymers are synthesized from isatin and p-terphenyl (or biphenyl) under superacid catalysis. Subsequently, glycidyl trimethyl ammonium chloride (GTA) is employed as a grafting reagent for PIT and PIB. This ring-opening reaction is accomplished through an efficient and environmentally friendly procedure without any alkaline catalysts. The introduced GTA side chains with quaternary ammonium and hydroxyl groups not only produce microphase separation structures that facilitate proton conduction, but also reduce PA loss. Comparing with PIT-GTA with terphenyl units, the PIB-GTA membrane with short biphenyl units exhibits superior properties. For instance, the PIB-GTA/218.5%PA membrane achieves a high conductivity of 0.103 S cm−1 at 180 °C and a tensile strength of 6.6 MPa at room temperature. Without humidification and backpressure, the PIB-GTA/218.5%PA based H2–O2 single cell displays a peak power density of 632 mW cm−2 at 160 °C. This work presents a straightforward approach to synthesizing GTA grafted poly(isatin arylene) membranes for HT-PEM fuel cells.

Novel approach: Simultaneous application of ionic liquid doped polymer electrolyte in supercapacitor and dye-sensitized solar cells

The present study reports the synthesis, characterization, and application as energy devices of an ionic liquid blended polymer electrolyte film in which the host polymer polyvinyl alcohol (PVA) is mixed with low viscosity ionic liquid (IL) 1-ethyl-3-methylimidazolium thiocyanate. Various characterization tools have been used further to elaborate electrical, structural, and photoelectrochemical properties. X-ray diffraction (XRD) and polarized optical microscope (POM) affirm the reduction of crystallinity of polymer, while Fourier transform infrared spectroscopy (FTIR) shows complexation and composite nature. Electrochemical impedance spectroscopy shows an enhancement in ionic conductivity by IL doping, where the highest conductivity is achieved at 60 wt% of IL concentration with a conductivity value of 6.21 × 10⁻⁴ S/cm. The ionic transference number (tion) and electrochemical stability measurement show the film's predominantly ionic nature and a reasonable stability window. Using maximum conducting film sandwiched between electrodes, we have successfully fabricated two devices, i.e., an electrical double-layer capacitor (EDLC) and a dye-sensitized solar cell (DSSC). The fabricated EDLC capacitor shows a specific capacitance of 125 F/g, while DSSC shows an efficiency of 1.1 % at one sun condition.

Poly(Vinylidene Fluoride‐CO‐Hexafluoropropylene) (PVDF‐HFP) Incorporated Acetylene Black: Electrical, Optical, and Structural Studies

AbstractThe primary goal of this study is to synthesize a high‐conducting polymer electrolyte film. The PVDF‐HFP and NaSCN film are prepared which showed the highest conductivity at 30 wt% dopant of NaSCN in the Polymer PVDF‐HFP which is 1.24× 10−4 S cm−1. Therefore, here the base polymer is taken as PVDF‐HFP and NaSCN (30 wt%) and further Acetylene Black is added to check the variation in the conductivity of the polymer film. Solution casting technique is used to create solid polymer electrolyte films using poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) with salt sodium thiocyanate and Acetylene Black. Polarized optical microscopy (POM) is used to evaluate the morphology of the polymer film surface. Fourier transform infrared spectroscopy (FTIR) to check the presence of functional group is used, impedance spectroscopy is used for the measurement of the conductivity of the sample, linear sweep voltammetry for finding electrical stability window, and transference number measurements for concentration of charge carriers are done for the electrical studies of polymeric films. The 1 wt% Acetylene Black doped polymer electrolyte film is found to have the maximum ionic conductivity, which is 1.95 × 10−3 S cm−1. The solid polymer electrolyte film has an electrochemical stability window (ESW) of 4.8 V and tion value of 0.83.

Ion Conducting Polyethylene Oxide‐Based Polymer Electrolyte Dopped with Ionic Liquid‐Trifluoromethanesulfonic Chloride

AbstractIn last few decades, polymer electrolyte is the most promising candidate for the fabrication of electrochemical devices. In current work, the influence of adding the room‐temperature ionic liquid (trifluoromethanesulfonic chloride – CClF3O2S) in polyethylene oxide (PEO): ammonium iodide (NH4I) polymer electrolyte has been studied. The IL‐doped polymer electrolyte films are synthesized by solution casting method with varying stoichiometric ratios. Several experimental techniques including optical polarizing microscope, impedance spectroscopy, X‐ray diffraction, Linear sweep voltammetry, Ionic transference number thermal analysis, and electrical conductivity measurements at room temperature have been studied in detail. The complex material's maximum conductivity has been determined to be 3.3 × 10−5 S cm−1 at room temperature. The POM images show the increase in amorphous region which further confirm the improvement in ionic conductivity. Ionic transference number 0.96 shows the system is purely ionic in nature. The ESW of the IL doped polymer electrolyte is also sawed to be 3.32 V which is suitable for the fabrication of electrochemical devices.

Current scenario and future aspect of low viscosity doped polymer electrolyte

This paper deals the overall response of mixing ionic liquid into polymer matrix. Ionic liquid is frequently used as novel electrolyte in various electrochemical devices. Mixing ionic liquid into insulator polymers plays dual role. One side it plays as source of charge carriers while in other side it acts as plasticizer when incorporated in polymer matrix. For device application high conducting polymer electrolyte is necessary which can easily be provided by this ionic liquid when used as dopants. It is also necessary to understand detail conduction mechanism within ionic liquid incorporated polymer electrolyte. Possible reasons of conductivity enhancement are discussed in detail in present work.

Current Scenario and Future Prospective of Ionic‐Liquid Doped Polymer Electrolyte for Energy Application

AbstractSolid polymer electrolyte (SPE) films based on poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF–HFP) with salt and ionic‐liquid (IL) are synthesized using the solution‐cast technique and summarized in this review. Doping ILs or salts increases ionic conductivity up to the device level. This is further confirmed using differential scanning calorimetry (DSC) and X‐ray diffraction (XRD) measurements. Polarized optical microscopy (POM) affirms that enhancement in ionic conductivity is due to increase in amorphous nature of film. The complex nature of polymer electrolyte films is confirmed using Fourier transform infrared (FT‐IR) spectroscopy. Overall results show that doping IL into polyether matrix is advantageous material playing a dominant role in electrochemical devices.

Ionic liquid (1-ethyl-3-methyltricynomethanide) doped polymer electrolyte (polyvinyl alcohol) for sustainable energy devices

Ionic liquid (1-ethyl-3-methyltricynomethanide) doped polymer electrolyte (polyvinyl alcohol) for sustainable energy devices

Investigation of structural and conductivity properties of poly(vinyl alcohol)‐based electrospun composite polymer blend electrolyte membranes for battery applications

AbstractSolid polymer electrolyte has attracted great interest for the next generation of electrochemical devices such as batteries, but the low ionic conductivity and poor stability has retarded their commercial acceptance for energy storage devices applications. To overcome these issues, strategies to develop composite polymer electrolytes (CPEs) are drawing interest. Nanocomposite solid polymer blend electrolyte membranes based on poly (vinyl alcohol) (PVA), poly (vinyl pyrrolidone) (PVP) of various compositions that contained potassium nitrate (KNO3) as a dopant salt, and Barium Titanate (BaTiO3) as a filler were prepared with various concentrations of filler using electrospinning technique. The structural and complex formations due to interaction of various groups of the prepared composite polymer electrolyte membranes were investigated using X‐ray diffraction (XRD) and Fourier transform infra‐red (FTIR) spectral analysis. The conductivity of the PVA‐PVP‐KNO3‐BaTiO3 polymer electrolyte systems was found to vary between 3.71×10‐9 and 1.99×10‐5 S cm‐1 at 298 K with the increase in filler concentration. The maximum room temperature ionic conductivity (1.99×10‐5 S cm‐1) has been obtained for 9 wt% BaTiO3 doped polymer electrolyte system. The addition of filler also enhanced the thermal stability of the electrolyte. The temperature dependence ionic conductivity of the prepared complexed polymer electrolyte systems appears to obey Arrhenius behaviour.

Proton Conductor Confinement Strategy for Polymer Electrolyte Membrane Assists Fuel Cell Operation in Wide‐Range Temperature

AbstractAcid loss and plasticization of phosphoric acid (PA)‐doped polymer electrolyte membranes are critical hampers for its actual application especially during startup/shutdown stages due to the produced water and thermal stress. To conquer these barriers, a proton conductor confinement strategy is introduced, which may trap PA molecules in the side‐chain acidophilic microphase and weaken plasticizing effect caused by PA toward the polymer backbone to remain membrane tensile stress. The grafted polyphenylene oxide (PPO) is synthesized as model polymers, both molecular electrostatic potential and molecular dynamics reveal the retention mechanism between PA and side‐chain of PPO as well as the aggregation state of PA. Through precisely regulating polymer side‐chain structure and defined plasticization quantitative indicator, significant refinements in membrane's conductivity, durability, and single‐cell performance are achieved successfully. The designed PPO membranes exhibit ultra‐fast and stable proton conducting even at low proton carrier concentrations and under wide‐range working temperature between 80 oC–180 °C as well as satisfied resistance to harsh accelerated aging test. These insights will shed light on holistic understanding of PA interactions and retention from molecular level, and provide radical approaches toward high‐performance PA/PEMs design.

Structural, conductivity and dielectric studies of pure and KCL doped polymer electrolyte films

Using the solution cast method, poly (vinyl alcohol) complexed with KCl was used to make solid polymer electrolyte films. XRD was used to look at the structure of these films. The outcomes of the Powder × - ray diffraction show that the composite films had more noncrystalline phases of PVA matrix. An AC impedance spectroscopy suggested that the ionic conductivity mainly arisen from grain effect. Conductivity of pure PVA is found to be of the order of 10-8 S/cm. With the addition of 20 wt% of KCl, the conductivity is dropped to the order of 10-10 S/cm, and then increased with the addition of KCl. The increase in conductivity with dopant type is based on the ionic character of the dopant. Real part of Impedance (Z') and imaginary part of impedance (Z“) of pure PVA and various composite films with 20 wt% of KCl, additives with different weight ratios were measured as a function of frequency. Dielectric permittivity and dielectric loss of all PVA with KCl 20 wt% of Polymer films investigated as a function of frequency at a room temperature is studied.Different electrochemical applications can be developed using these kinds of solid electrolytes.

Highly conducting ionic liquid doped polymer electrolyte for energy storage applications

The main aim of the present work is to optimize highly conducting solid polymer electrolyte by doping of ionic liquid in Poly-ethylene oxide (PEO) polymer complexed Sodium Iodide (NaI) matrix. Solution casting method has been used to synthesis solid polymer electrolyte. Electrical, thermal, structural, and optical studies confirm the homogenous complexation of polymer electrolyte with ionic liquid. Furthermore, the electric double-layer capacitors (EDLCs) device and Dye Sensitized Solar Cell (DSSC) has been developed using high conducting ionic liquid (IL) polymer electrolyte with maximum conductivity, demonstrating that ionic liquids have a potential possibility to choose as electrolyte in developed energy devices.

Study of Pt Alloy Catalysts for Oxygen Reduction Reaction on Rde and in MEA for High-Temperature Pemfcs

High-temperature polymer electrolyte fuel cells (HT-PEMFCs) have advantages in enhanced fuel impurities tolerance, easier heat rejection, and simpler water management[1]. Low-temperature PEMFCs with perfluorosulfonic acid electrolytes (e.g., Nafion) could not provide sufficient proton conductivity in the absence of water when T > 120 °C, limiting the application when a higher temperature is desired. High-temperature (HT-) PEMFCs have been developed by using phosphoric acid (H3PO4)-doped polymer electrolyte (e.g., polybenzimidazole, quaternary ammonium biphosphate ion pair coordinated polyphenylene, etc.) [2-4], where H3PO4 can conduct proton at high temperature up to 200 °C. Such change of the reaction environment, however, also affects oxygen reduction reaction (ORR) kinetics. Despite of a facilitated reaction kinetics under high temperature, a high Pt loading is still demanded in state-of-the-art HT-PEMFCs. To enhance ORR activity and increase Pt utilization, here we employ a strategy to alloy Pt with another transition metal (M), which has been demonstrated to be effective in LT-PEMFCs. In this study, Pt and Pt-M catalysts were used to investigate the alloy effect on the adsorption strength of H3PO4 and ORR in both half-cell rotating disk electrode (RDE) and membrane electrode assembly (MEA). In RDE study, the competition adsorption of phosphoric acid has led to a suppression on ORR activity on all catalysts, with less impact on ORR at 160 °C using pure H3PO4 than RT using 1 M H3PO4. Since alloying not just affects the O binding energy, but also H3PO4 adsorption, a different trend of ORR on Pt-M alloy catalysts was resulted in the presence of H3PO4. The alloy effect was further studied in MEA at 160 °C, which also indicates the effectiveness of using HT-RDE setup for HT-ORR catalyst screening. Reference: [1] Gittleman, C. S.; Jia, H.; De Castro, E. S.; Chisholm, C. R. I.; Kim, Y. S. Proton Conductors for Heavy-Duty Vehicle Fuel Cells. Joule 2021, 5 (7), 1660–1677.[2] Pingitore, A. T.; Huang, F.; Qian, G.; Benicewicz, B. C. Durable High Polymer Content m/ p-Polybenzimidazole Membranes for Extended Lifetime Electrochemical Devices. ACS Appl. Energy Mater. 2019, 2 (3), 1720–1726.[3] Lee, K. S.; Spendelow, J. S.; Choe, Y. K.; Fujimoto, C.; Kim, Y. S. An Operationally Flexible Fuel Cell Based on Quaternary Ammonium-Biphosphate Ion Pairs. Nat. Energy 2016, 1 (9).[4] Lim, K. H.; Lee, A. S.; Atanasov, V.; Kerres, J.; Park, E. J.; Adhikari, S.; Maurya, S.; Manriquez, L. D.; Jung, J.; Fujimoto, C.; Matanovic, I.; Jankovic, J.; Hu, Z.; Jia, H.; Kim, Y. S. Protonated Phosphonic Acid Electrodes for High Power Heavy-Duty Vehicle Fuel Cells. Nat. Energy 2022, 7 (3), 248–259.

Influence of ZnO Nanoparticle Doped Polymer Electrolyte Gel Membranes for H+ Ion Conduction Based Electrochemical Clean Energy Applications

Polymer Science: Peer Review Journal Influence of ZnO Nanoparticle Doped Polymer Electrolyte Gel Membranes for H+ Ion Conduction Based Electrochemical Clean Energy Applications Neelesh Rai*, Lovely Ranjta* and C P Singh Department of Physics, AKS University, India *Corresponding author: Neelesh Rai and Lovely Ranjta, Department of Physics, AKS University, Satna (MP), 485001, India Submission: August 01, 2022;Published: August 26, 2022 DOI: 10.31031/PSPRJ.2022.04.000581 ISSN: 2770-6613 Volume4 Issue2

Highly efficient ionic‐liquid based solid polymer electrolyte for energy device (RAFM 2022)

We have successfully synthesized highly conducting polymer electrolyte incorporated ionic liquid films. There was a rise in conductivity by ionic liquid doping which is clarified by impedance spectroscopy. Fourier transform infra red spectroscopy confirms complexation as well as composite nature. Polarized optical microscopy shows decrease in crysatllinity (more amorphous) by ionic liquid doping. Maximum conducting ionic liquid incorporated polymer electrolyte sandwitched between electrodes, used for fabricating electrical double layer capacitor (EDLC) and dye sensitized solar cell (DSSC) further affirm that these ionic liquid doped polymer electrolyte could be a novel alternative in electrochemical devices.

Structural, optical and electrical properties of anhydrous GdCl3 doped PEO polymer electrolyte films

GdCl3 doped PEO polymer electrolyte films were prepared using solution casting technique. XRD patterns, FTIR spectra and optical absorption studies confirm an amorphous nature and the formation of the polymer electrolyte films. The ionic conductivity increases with the GdCl3 content and the maximum value at room temperature is about 1.8310-2 S/cm for 20 mol% GdCl3doped PEO film. This value is more than two orders of magnitude larger than the ionic conductivity of NASICON type Gd-doped solid electrolytes and other polymer electrolytes. The results suggest that the Gd3+ doped PEO polymer electrolyte films are good candidates for future electrochemical devices.

Quaternary ammonium-biphosphate ion-pair based copolymers with continuous H+ transport channels for high-temperature proton exchange membrane

Phosphoric acid (PA)-doped polymer electrolyte membranes are the most promising materials for high-temperature proton exchange membranes (HT-PEMs). However, their development is subject to the compromise between proton conductivity and phosphoric acid (PA) doping level. Here, an ether-free QPAF-4 membrane (a copolymer containing perfluoroalkylene and fluorenyl groups with pendant ammonium groups) is directly doped with phosphoric acid and studied as HT-PEMs. Due to the intrinsic micro-phase separation structure of QPAF-4 matrix and strong interaction of quaternary ammonium (QA)-PA, the PA-doped membranes possess high proton conductivity and eminent PA retention at comparatively low PA doping level, respectively. The QPAF-4 membrane with 150% PA uptake (QPAF-4-150%PA) offers a proton conductivity of 52 mS cm−1 at 160 °C. As expected, the single cell with QPAF-4-150%PA membrane shows the maximum peak power density of 683 mW cm−2 at 160 °C under anhydrous condition. Meanwhile, the single cell exhibits excellent durability over a period of 60 h with only a slight reduction in voltage of 3.1%. These results indicate that the as-prepared PA-doped quaternized polymer with micro-phase separation structure seems to offer a promising way to develop performing and long-life HT-PEMs with low PA doping levels.

Effect of Glycerin on Electrical and Thermal Properties of PVA/Copper Sulphate Gel Polymer Electrolytes

Copper-ion conducting gel polymer electrolyte (GPE) systems based on polymer poly(vinyl alcohol) (PVA) and copper sulphate salt doped with glycerin as plasticizer have been synthesized by using solution casting technique. Differential scanning calorimetry (DSC) is used to examine the thermal effect of glycerin on a polymer electrolyte. With the addition of various quantities of glycerin, as a plasticizer in pure PVA and PVA + 20 wt% CuSO4 polymer electrolyte shows a decrease in the values of melting temperature, glass transition temperature and percentage of crystallinity. From TGA curves, it is observed that thermal degradation of the glycerin doped polymer electrolyte is shifted towards lower temperature when compared to pristine PVA and the weight loss of the polymer electrolyte increases with increase of glycerin concentration. From DTG analysis, the temperature of maximum decomposition for PVA is 283.4 °C and it is decreased by the addition of 20 wt% CuSO4 and upon increased concentration of the plasticizer from 1 to 3 mL of glycerin. For pure PVA and PVA + 20 wt% CuSO4, ε′ decreases with increasing glycerin concentration and is lowest at 3 mL glycerin concentration. The maximum ionic conductivity obtained was 9.39 × 10− 4 S/cm for PVA + 20 wt% CuSO4 + 3 mL glycerin gel polymer electrolyte. The above results suggested that, the optimum conducting sample is suitable as separator in rechargeable batteries.

Development of solid polymer electrolytes based on poly (ethylene oxide) complexed with 2-trifluoromethyl-4, 5-dicyanoimidazole lithium salt and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid for Li-ion batteries

Ion conducting solid polymer electrolyte films based on polymer poly (ethylene oxide) (PEO) complexed with 2-trifluoromethyl-4, 5-dicyanoimidazole lithium salt and ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide are synthesized using anhydrous acetonitrile as solvent. Prepared electrolyte films are characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), complex impedance spectroscopy and cyclic voltammetry techniques. Incorporation of IL into the PEO20-LiTDI polymer electrolyte changes different physicochemical properties of these materials. By characterizations, particularly XRD, DSC and ionic conductivity studies, the synthesized SPEs showed decreased crystallinity, melting points and increased ionic conductivity by the introduction of ionic liquid. The 40 wt% of IL doped polymer electrolyte showed an ionic conductivity of the order of 1.78 × 10−4 S/cm at 60°C with better thermal stability. The optimum conducting composition showed very good electrochemical stability window at ambient temperature. These results suggested that the IL-doped polymer electrolyte would be a potential separator in Li-ion batteries.

In situ crosslinking of polyoxometalate-polymer nanocomposites for robust high-temperature proton exchange membranes

The most practical high-temperature proton exchange membranes (PEMs) are phosphoric acid (PA)-doped polymer electrolytes. However, due to the plasticizing effect of PA, it is a challenge to address the trade-off between the proton conductivity and the mechanical performance of these materials. Here, we report an effective strategy to fabricate robust high-temperature PEMs based on the in situ electrostatic crosslinking of polyoxometalates and polymers. A comb copolymer poly(ether-ether-ketone)-grafted-poly(2-ethyl-2-oxazoline) (PGE) with transformable side chains was synthesized and complexed with H3PW12O40 (PW) by electrostatic self-assembly, forming PGE/PW nanocomposite membranes with bicontinuous nanostructures. After a subsequent PA-treatment of these membranes, high-temperature PEMs of PGE/PW/PA ternary nanocomposites were obtained, in which the in situ electrostatic crosslinking effect between PW and PGE side chains was generated in the hydrophilic domains of the bicontinuous structures. The microphase separation structure and the electrostatic crosslinking feature endow the PGE/PW/PA membranes with excellent anhydrous proton conductive ability while retaining high mechanical performance. The membranes show a high proton conductivity of 42.5 mS/cm at 150 °C and a high tensile strength of 13 MPa. Our strategy can pave a new route based on electrostatic control to design nanostructured polymer electrolytes.

Ionic liquid doped solid polymer electrolyte: Synthesis, characterization and applications ICSEM-2021

In this paper, we have used polymer polyethylene oxide as a host matrix and novel electrolyte ionic liquid 1-ethyl-3-methylimidazolium tricyanomethanide as an dopant to increase ionic mobility. Different characterization techniques like Electrochemical impedance spectroscopy, dielectric measurement, Fourier transform, X-ray diffraction, polarized optical microscopy, thermogravinometric analysis were used to identify the electrical, optical, structural and thermal properties. A laboratory scale supercapacitor has been fabricated using optimized solid polymer electrolyte film as an electrolyte and porous carbon derived from corn starch which shows a specific capacitance 13.6 F/g at 50 mV/s scan rate.