Electrochemical performances of gel polymer electrolytes using tetra(ethylene glycol) diacrylate

A gel polymer electrolyte (GPE) was prepared using tetra(ethylene glycol) diacrylate monomer, benzoyl peroxide, and (). The LiCoO₂/GPE/graphite cells were prepared and their electrochemical properties were evaluated at various current densities and temperatures.The viscosity of the precursor containing the tetra(ethylene glycol) diacrylate monomer was around . The ionic conductivity of the gel polymer electrolyte at 20°C was around . The gel polymer electrolyte had good electrochemical stability up to vs. Li/Li⁺. The capacity of the LiCoO₂/GPE/graphite cell at rate was 63% of the discharge capacity at rate. The capacity of the cell at −10°C was 81% of the discharge capacity at 20°C. Discharge capacity of the cell with gel polymer electrolyte was stable with charge-discharge cycling.     

Electrochemical characteristics of a new electric double layer capacitor with acidic polymer hydrogel electrolyte

The article presents the results of a study on activated carbon fiber cloth (AC) and a hydrophobic microporous polypropylene (PP) membrane, both chemically modified with acidic acetone aldol condensation products, and on testing their use as an electrode material and separator in electric double layer capacitors (EDLCs). Polymer hydrogel used was based on poly(acrylamide) (PAAM), H₂SO₄ and water. Electrochemical characteristics of EDLCs were investigated by cyclic voltammetry and galvanostatic charge–discharge cycle tests and also by impedance spectroscopy. As a result, the capacitor with polymer hydrogel was found to exhibit similar capacitance as that with the H₂SO₄ aqueous solution and an excellent high-rate dischargeability. At the 4000th cycle of potential cycling (0.5 A g⁻¹) the specific capacitance of 132 F g⁻¹ was obtained with a energy density of 3.45 Wh kg⁻¹ at a power density of 56 W kg⁻¹. The above results provide valuable information to explore the novel composition of EDLCs.     

Electrochemical characterization of new electric double layer capacitor with polymer hydrogel electrolyte

A new electric double layer capacitor (EDLC) was constructed by using polymer hydrogel electrolyte prepared from crosslinked potassium poly(acrylate) and KOH aqueous solution, and its electrochemical characteristics were investigated by cyclic voltammetry and charge-discharge cycle tests, compared with a case of the cell using only a KOH aqueous solution as an electrolyte. As a result, the cell with the polymer hydrogel electrolyte was found to exhibit higher capacitance than that with the KOH aqueous solution and excellent high-rate dischargeability. The impedance spectroscopic measurements suggested that the higher capacitance could be ascribed to the pseudocapacitance. These results indicate the potential applicability of the polymer hydrogel electrolyte to EDLCs as an electrolyte with good performance.     

Preparation and physicochemical performances of poly[(vinylidene fluoride)‐co‐hexafluoropropylene]‐based composite polymer electrolytes doped with modified carbon nanotubes

Modified carbon nanotubes (m‐CNTs) were successfully prepared by the interactions between nitric and sulfuric acids and CNTs, which was confirmed using Fourier transform infrared spectroscopy. Poly[(vinylidene fluoride)‐co‐hexafluoropropylene]‐based composite polymer electrolyte (CPE) membranes doped with various amounts of m‐CNTs were prepared by phase inversion method. The desired CPEs were obtained by soaking the liquid electrolytes for 30 min. The physicochemical and electrochemical properties of the CPE membranes were investigated using scanning electron microscopy, X‐ray diffraction, thermogravimetry, electrochemical impedance spectroscopy and linear sweep voltammetry. The results show that the CPE membranes doped with 2.2 wt% m‐CNTs possess the smoothest surface and the highest decomposition temperature about 450 °C. Obviously, adding an appropriate amount of m‐CNTs into the polymer matrix can decrease the crystallinity and enhance the ionic conductivity; the temperature dependence of ionic conductivity follows the Arrhenius relation and the ionic conductivity at room temperature is up to 4.9 mS cm^?1. The interfacial resistance can reach a stable value of about 415 Ω cm^?2 after 10 days storage. The excellent rate and cycle performances with an electrochemical working window up to 5.4 V ensure that the CPEs doped with 2.2 wt% m‐CNTs can be considered as potential candidates as polymer electrolyte for lithium ion batteries. © 2013 Society of Chemical Industry     

Electric double layer capacitors with gelled polymer electrolytes based on poly(ethylene oxide) cured with poly(propylene oxide) diamines

Using a gel electrolyte for electric double layer capacitors usually encountered a drawback of poor contact between the electrolyte and the electrode surface. A gel electrolyte consisting of poly(ethylene oxide) crosslinked with poly(propylene oxide) as a host, propylene carbonate (PC) as a plasticizer, and LiClO₄ as a electrolytic salt was synthesized for double layer capacitors. Diglycidyl ether of bisphenol-A was blended with the polymer precursors to enhance the mechanical properties and increase the internal free volume. This gel electrolyte showed an ionic conductivity as high as 2 × 10⁻³ S cm⁻¹ at 25 °C and was electrochemically stable over a wide potential range (ca. 5 V). By sandwiching this gel-electrolyte film with two activated carbon cloth electrodes (1100 m² g⁻¹ in surface area), we obtained a capacitor with a specific capacitance of 86 F g⁻¹ discharged at 0.5 mA cm⁻², while the capacitance was 82 F g⁻¹ for a capacitor equipped with a liquid electrolyte of 1 M LiClO₄/PC. The capacitance decrease with the current density was less significant for the gel-electrolyte capacitor. We found that the less restricted ion diffusion near the electrolyte/electrode interface led to the smaller overall resistance of the gel-electrolyte capacitor. The high performance of the gel-electrolyte capacitor has demonstrated that the developed polymer network not only facilitated ion motion in the electrolyte bulk phase but also gave an intimate contact with the carbon surface. The side chains of the polymer in the amorphous phase could stretch across the boundary layer at the electrolyte/electrode interface to come into contact with the carbon surface, thus improving transport of Li⁺ ions by the segmental mobility in polymer.     

Electrochemical characteristics of phase-separated polymer electrolyte based on poly(vinylidene fluoride-co-hexafluoropropane) and ethylene carbonate

A polymer electrolyte based on microporous poly(vinylidene fluoride-co-hexafluoropropane) (PVdF-HFP) film was studied for use in lithium ion batteries. The microporous PVdF-HFP (Kynar 2801) matrix was prepared from a cast of homogeneous mixture of PVdF-HFP and solvents such as ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC). After evaporation of DMC and EMC, a sold film of the PVdF-HFP and the EC mixture was obtained. EC-rich phase started its formation in the PVdF-HFP/EC film at EC content of about 60 wt.% based on the total weight of PVdF-HFP and EC. The formation of the new phase resulted in the abrupt increase of the porosity of the PVdF-HFP matrix from 32 to 62%. The ionic conductivity of the film soaked in 1 M LiPF₆-EC/DMC=1/1 was significantly increased from order of 10⁻⁴ S/cm to order of 10⁻³ S/cm at the EC content of 60 wt.%. Thermal and spectroscopic investigations showed that most of the EC interact with PVdF-HFP with the EC content being below 60 wt.%. MCMB/polymer electrolyte/LiCoO₂ cells employing the microporous PVdF-HFP polymer film showed stable charging/discharging characteristics at 1C rate and good rate capability.     

Influence of 2,6 (N-pyrazolyl)isonicotinic acid on the photovoltaic properties of a dye-sensitized solar cell fabricated using poly(vinylidene fluoride) blended with poly(ethylene oxide) polymer electrolyte

A novel method of introducing a synthesized organic nitrogenous compound 2,6 (N-pyrazolyl)isonicotinic acid (BNIN) and its effect on the conduction behavior of poly(vinylidene fluoride) (PVdF)–poly(ethylene oxide) (PEO) polymer-blend electrolyte with potassium iodide (KI) and iodine (I₂) and the corresponding performance of the dye-sensitized solar cells (DSSCs) were studied. A systematic investigation of the blends using FTIR provides evidence of interaction of BNIN with the polymer. Differential scanning calorimetry (DSC) study proves the miscibility of these polymers. Due to the coordinating and plasticizing effects of BNIN, the ionic conductivity of polymer blend electrolytes is enhanced. The efficiency of DSSC using BNIN doped polymer blend electrolyte was 7.3% under an illumination of 60 mW cm⁻² were observed for the best performance of a solar cell in this work.     

Electrochemical properties of gel polymer electrolyte based on poly(acrylonitrile)-poly(ethylene glycol diacrylate) blend

Gel type electrolyte was formulated by blending of PEDGA and PAN. PEDGA is a UV curable polymer which forms a chemical crosslink by UV or heat. Gel type electrolyte is very stable in ionic conductivity and interfacial resistance for a long storage time. It has the advantage of manufacturing the battery in a continuous process because oligomer crosslinking occurs in few seconds without heating. Discharge capacity and cycle life were increased by using LiPF₆/LiCF₃SO₃ mixed lithium salt and adding inorganic filler such as TiO₂.     

Preparation of monodispersed ZrO2 nanoparticles and their applications in poly[(vinylidene fluoride)‐co‐hexafluoropropylene]‐based composite polymer electrolytes

To improve the electrochemical performance of pure poly[(vinylidene fluoride)‐co‐hexafluoropropylene] (P(VDF‐HFP))‐based gel polymer electrolytes, different amounts of monodispersed ZrO₂ nanoparticles were introduced to fabricate P(VDF‐HFP)/ZrO₂ composite polymer electrolytes (CPEs) using the phase inversion method and activated processes, in which the monodispersed ZrO₂ nanoparticles were synthesized by an easy route without any chelating agents or surfactants, and confirmed using scanning electron microscopy, particle size distribution measurement and X‐ray diffraction. The characterization results show that the as‐fabricated CPE membranes present not only an abundant porous structure, but also an improved mechanical strength. In particular, sample CPE‐5 presents the best properties when the doped content of the monodispersed ZrO₂ nanoparticles reaches 5 wt% in the polymer matrix, in which the liquid uptake and ionic conductivity at room temperature are about 192.4% and 3.926 mS cm^?1, and the electrochemical working window and thermal decomposition temperature can increase to 5.1 V and 420 °C, respectively. Moreover, an assembled LiCoO₂/CPE‐5/Li coin cell can deliver excellent rate and cycling performance, in which the discharge specific capacity of the cell can show about 83.95% capacity retention at 2.0 C after 85 cycles. © 2018 Society of Chemical Industry     

Electrochemical characteristics of electric double layer capacitor using sulfonated polypropylene separator impregnated with polymer hydrogel electrolyte

Sulfonated polypropylene separators impregnated with the polymer hydrogel electrolyte were used in electric double layer capacitors (EDLCs). The electrochemical properties of the EDLC with the polymer hydrogel electrolyte were investigated by cyclic voltammetry and charge-discharge cycle tests and compared with a KOH aqueous electrolyte. Furthermore, effects of KOH concentration and temperature on capacitance of the EDLC were studied. As a result, it was found that the capacitance of the EDLC with the polymer hydrogel electrolyte was higher than that with a KOH aqueous solution in the wide range of KOH concentration and temperature.     

A microporous gel electrolyte based on poly(vinylidene fluoride-co-hexafluoropropylene)/fully cyanoethylated cellulose derivative blend for lithium-ion battery

A gel polymer electrolyte based on the blend of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and fully cyanoethylated cellulose derivative (DH-4-CN) was prepared and characterized. Thermal, mechanical, swelling, liquid electrolyte retention and electrochemical properties, as well as microstructures of the prepared polymer electrolytes, were investigated using thermogravimetric analysis, electrochemical impedance spectroscopy, linear sweep voltammetry, and scanning electron microscopy. The results showed that the addition of DH-4-CN could obviously improve the conductivity of PVDF-HFP based electrolyte. The maximum ionic conductivity of 4.36 mS cm⁻¹ at 20 °C can be obtained for PVDF-HFP/DH-4-CN 14:1 in the presence of 1 M LiPF₆ in EC and DMC (1:1, w/w). The dry blend membranes exhibit excellent thermal behavior. All the blend electrolytes are electrochemically stable up to about 4.8 V vs. Li/Li⁺ for all compositions. The results reveal that the composite polymer electrolyte qualifies as a potential application in lithium-ion battery.     

Controlled synthesis and characterizations of amphiphilic poly[(R,S)-3-hydroxybutyrate]-poly(ethylene glycol)-poly[(R,S)-3-hydroxybutyrate] triblock copolymers

Well-defined biodegradable amphiphilic triblock copolymers consisting of atactic poly[(R,S)-3-hydroxybutyrate] (PHB) and poly(ethylene glycol) (PEG) as the side hydrophobic block and middle hydrophilic block were synthesized via ring opening polymerization of (R,S)-β-butyrolactone from PEG macroinitiators and characterized using NMR, GPC, FT-IR, XRD, DSC and TG analyses. The controlled synthesis was made possible by the facile synthesis of pure PEG macroinitiators through a TEMPO-mediated oxidation. Constituting 40-70 wt% of the copolymer content, PHB blocks grown were amorphous while PEG formed crystalline phase when segment was sufficiently long. While hindering PEG crystallization, atactic PHB mixed well with amorphous PEG to give single T_g in all the copolymers. The copolymers exhibited two-step thermal degradation profile starting with PHB degradation from 210 to 300 °C, then PEG from 350 to 450 °C.     

Nanocomposites of polymer gel electrolyte based on poly(ethylene glycol diacrylate) and Mg–Al layered double hydroxides

The present paper describes the synthesis and characterization of nanocomposite materials composed of the polymer gel electrolyte and a layered double hydroxide (LDH) inorganic filler. Mg–Al LDHs were prepared with various ratios of Mg/Al. It was observed that the layered structure of Mg–Al LDH was totally exfoliated by the PEGDA. The ionic conductivity and mechanical strength were highly improved in the nanocomposite systems. In the case of the composite films having 4.5 wt% of the Mg–Al LDH, the ionic conductivity reached 1.6 × 10^?3 S cm^?1 at room temperature. The incorporation of nanoparticles into the gel resulted in a two‐ or threefold increase in the tensile modulus. Copyright © 2004 Society of Chemical Industry     

Electric double layer capacitors with polymer hydrogel electrolyte based on poly(acrylamide) and modified electrode and separator materials

Activated carbon fiber cloths (AC) and hydrophobic microporous polypropylene (PP) membrane, both modified by acetone aldol condensation products, and filled with polymer hydrogel were used as electrodes, separator and electrolyte in electric double layer capacitors (EDLCs). Polymer hydrogel used was based on poly(acrylamide) (PAAM), KOH and water. Electrochemical characteristics of EDLCs were investigated by cyclic voltammetry and galvanostatic charge–discharge cycle tests and also by impedance spectroscopy, compared with a case of the capacitor with only a KOH aqueous solution used as an electrolyte. As a result, the capacitor with polymer hydrogel was found to exhibit higher capacitance than that with the KOH aqueous solution and an excellent high-rate dischargeability. The above results provide valuable information to explore novel composition of EDLCs.     

Influence of solvent on the poly (acrylic acid)-oligo-(ethylene glycol) polymer gel electrolyte and the performance of quasi-solid-state dye-sensitized solar cells

The influence of solvents on the property of poly (acrylic acid)-oligo-(ethylene glycol) polymer gel electrolyte and photovoltaic performance of quasi-solid-state dye-sensitized solar cells (DSSCs) were investigated. Solvents or mixed solvents with large donor number enhance the liquid electrolyte absorbency, which further influences the ionic conductivity of polymer gel electrolyte. A polymer gel electrolyte with ionic conductivity of 4.45 mS cm⁻¹ was obtained by using poly (acrylic acid)-oligo-(ethylene glycol) as polymer matrix, and absorbing 30 vol.% N-methyl pyrrolidone and 70 vol.% γ-butyrolactone with 0.5 M NaI and 0.05 M I₂. By using this polymer gel electrolyte coupling with 0.4 M pyridine additive, a quasi-solid-state dye-sensitized solar cell with conversion efficiency of 4.74% was obtained under irradiation of 100 mW cm⁻² (AM 1.5).     

Sulfonated polyimide and poly (ethylene glycol) diacrylate based semi‐interpenetrating polymer network membranes for fuel cells

Semi‐interpenetrating polymer network (semi‐IPN) membranes based on novel sulfonated polyimide (SPI) and poly (ethylene glycol) diacrylate (PEGDA) have been prepared for the fuel cell applications. SPI was synthesized from 1,4,5,8‐naphthalenetetracarboxylic dianhydride, 4,4′‐diaminobiphenyl 2,2′‐disulfonic acid, and 2‐bis [4‐(4‐aminophenoxy) phenyl] hexafluoropropane. PEGDA was polymerized in the presence of SPI to synthesize semi‐IPN membranes of different ionic contents. These membranes were characterized by determining, ion exchange capacity, water uptake, water stability, proton conductivity, and thermal stability. The proton conductivity of the membranes increased with increasing PEGDA content in the order of 10^?1 S cm^?1 at 90°C. These interpenetrating network membranes showed higher water stability than the pure acid polyimide membrane. This study shows that semi‐IPN SPI membranes based on PEGDA which gives hydrophilic group and structural stability can be available candidates comparable to Nafion® 117 over 70°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Fabrication and characterization of electrolyte membranes based on organoclay/tripropyleneglycol diacrylate/poly(vinylidene fluoride) electrospun nanofiber composites

Utilizing polymer electrospinning technology, novel electrolyte membranes based on poly(vinylidene fluoride) (PVDF)/organomodified clay (OC)/tripropyleneglycol diacrylate (TPGDA) composite nanofibers with a diameter of 100–400 nm were fabricated for application in lithium batteries. Ultraviolet photo‐polymerization of electrospun PVDF/OC/TPGDA nanofibers generated chemically crosslinked TPGDA‐grafted PVDF/OC nanofibers exhibiting robust mechanical and electrochemical properties. The prepared fibrous PVDF/OC/TPGDA electrolytes were characterized in terms of morphology, crystallinity, electrochemical stability, ionic conductivity and cell cycleability. Based on differential scanning calorimetry analysis, the crystallinity of PVDF decreased by ca 10% on employing the OC and TPGDA. Compared with pure PVDF film‐based electrolyte membranes, the TPGDA‐ and OC‐modified PVDF electrolyte membranes exhibited improved mechanical properties and various electrochemical properties. The OC‐ and TPGDA‐modified microporous membranes are promising candidates for overcoming the drawbacks of the lower mechanical stability of fibrous‐type electrolytes with further improvement of electrochemical performance. Copyright © 2009 Society of Chemical Industry     

Structure and characterization of poly[(vinylidene fluoride)‐co‐hexafluoropropene]–(dibutyl phthalate) blends

Blends of poly[(vinylidene fluoride)‐co‐hexafluoropropene] with dibutyl phthalate were examined by wide‐ and small‐angle X‐ray scattering, differential scanning calorimetry and dynamic mechanical spectroscopy, in order to study the influence of amount of plasticizer and the crystallization rate on the crystallinity and lamellar morphology of the copolymer. The dibutyl phthalate seems, at least for the cooling and heating rates used, simply to dilute the crystalline phase without affecting the amount of polymer that is able to crystallize. Furthermore, the small‐angle X‐ray scattering technique points out that the plasticizer mostly enters the amorphous phase either outside or inside the lamellar stacks. © 2001 Society of Chemical Industry     

Formation of nanostructured composites with environmentally-dependent electrical properties based on poly(vinylidene fluoride)-polyaniline core-shell latex system

Submicron poly(vinylidene fluoride) (PVDF)/polyaniline (PANI) core-shell latex particles are synthesized and examined as an active component in a simple conductometric chemical sensor. The structure and physical properties of these particles and nanostructured composite PVDF-PANI polymer films built of them are characterized with transmission electron, atomic force, and helium ion microscopy techniques, differential scanning calorimetry, and conductivity measurements. The nanostructured composite films with conductivity of about 4 × 10⁻⁴ S/cm suitable for sensor applications are prepared by casting from the core-shell particles dispersions on glass substrates patterned with silver electrodes followed by annealing at 180 °C, i.e. above T_m of the PVDF component. Sensor properties of these films are tested by measuring current-voltage (I-V) characteristics in response to varying concentration of NH₃ or HCl vapors. The developed thin film sensor heterostructures with electrically conductive percolation network of PANI as an active component and employing the conductometric detection scheme show high sensitivity to both analytes. However, the polymer material is especially efficient for application to NH₃ sensing with the detection limit as low as 100 ppb, and good reproducible recovery behavior upon repeated exposure to NH₃ at ambient conditions.     

Preparation of a microporous polymer electrolyte based on poly(vinyl chloride)/poly(acrylonitrile-butyl acrylate) blend for Li-ion batteries

Poly(acrylonitrile-co-butyl acrylate) (P(AN-co-BuA))/poly(vinyl chloride) (PVC) blend-based gel polymer electrolyte (BGPE) was prepared for lithium-ion batteries. The P(AN-co-BuA)/PVC BGPE consists of an electrolyte-rich phase, which is mainly composed of P(AN-co-BuA) and liquid electrolyte, acting as a conducting channel and a PVC-rich phase that provides mechanical strength. The dual phase was just simply developed by the difference of miscibility properties in solvent, PC, between P(AN-co-BuA) and PVC. The mechanical strength of this new blend electrolyte was found to be much higher, with a fracture stress as high as 29 MPa in dry membrane and 21 MPa in gel state, than that of a previously reported P(AN-co-BuA)-based gel polymer electrolyte. The blended gel polymer electrolyte showed ionic conductivity of higher than 1.5 × 10⁻³ S cm⁻¹ and electrochemical stability up to at least 4.8 V. The results showed that the as-prepared gel polymer electrolytes were promising materials for lithium-ion batteries.