Doped Polymer Electrolyte Research Articles

Ionic liquid incorporated poly (ethylene oxide) (PEO) doped with potassium iodide (KI) solid polymer electrolyte for energy device

In this paper, we have used solution cast technique to synthesize ionic liquid incorporated PEO (Poly(ethylene oxide) with KI (Potassium Iodide) doped polymer electrolyte. The ionic conductivity enhances rapidly after adding ionic liquid in polymer salt complex and reaches 4.2*10−4 S/cm. Characterization such as Fourier transform infrared spectroscopy (FTIR) and polarized optical microscopy (POM) was also done to check the blending nature and amorphousity of the developed polymer electrolyte. Finally, the supercapacitor has been developed using high conducting ionic liquid (IL) doped polymer electrolyte which shows the specific capacitance 12.28F/g at 5 mV/s.

Structural, Vibrational, Electrical, Electrochemical and Capacitive Investigations on Ionic Liquid Doped P (VDF-HFP) + NaSCN Based Polymer Electrolytes

Background: Solid polymer electrolyte (SPEs) films based on poly (vinylidene fluoride-co-hexafluoropropylene) P(VDF–HFP) and sodium thiocyanate (NaSCN) are prepared using the solution casting technique. Methods: Ionic liquid (IL; 1-ethyl-3-methyl-imidazolium tricyanomethanide ([EMIM] [TCM]) is incorporated into the prepared polymer-salt complex matrix to enhance its ionic conductivity further. Polarized optical microscopy (POM) shows a change in the surface morphology of IL doped polymer electrolyte films. The composite nature of polymer electrolyte films is confirmed using Fourier transform infrared (FT-IR) spectroscopy via studying ion-ion and ion-polymer interactions. The structural morphology of ionic liquid doped polymer electrolyte films (ILDPE) confirms the complexation between the ionic liquid ([EMIM][TCM]), salt (NaSCN) and polymer P(VDF-HFP). This is further confirmed using DSC and XRD measurements. The XRD structural analysis confirms that the intensity of crystalline peaks present in IL doped solid polymer electrolyte films decreases as compared to that of the pure polymer as well as polymer salt complex system. XRD clearly indicates the enhancement in its amorphous nature, which is necessary to increase the conductivity. Results: The incorporation of IL into polymer salt-complex matrix leads to changes in the melting of polymer electrolytes, confirmed by DSC thermograms. Polymer electrolyte films are also characterized using impedance spectroscopy (IS) to check their electrical properties. The highest ionic conductivity is found to be 7.80×10-4 S cm-1 for 6 wt% IL doped polymer electrolyte film. Conclusion: The Linear sweep voltammetry (LSV) analysis shows that the optimized polymer gel electrolyte is electrochemically stable up to 1.5 V. The calculated value of ionic transference number (tion) is found to be 0.985. A laboratory scale electrical double layer capacitor (EDLC) has been fabricated using this highly conducting polymer electrolyte film. The specific capacitance value is found to be 1.31 F g-1.

Ionic liquid incorporated polyvinylpyrrolidone (PVP) doped with ammonium iodide (NH4I) doped solid polymer electrolyte for energy device

In this work, we have used solution cast technique method to Synthesize an ionic liquid incorporated PVP with ammonium iodide doped solid polymer electrolyte. There was an inclination of one order conductivity in PVP-NH4I complex after addition of ionic liquid in it which was justified by complex impedance spectroscopy. Fourier transform infrared spectroscopy and Polarized optical microscopy was also done to check the blending nature and amorphousity of the polymer electrolyte. At last, we have successfully developed a supercapacitor using IL doped polymer electrolyte shows a reasonable and stable efficiency.

Thermal, Structural, Optical and Electrical Conductivity studies of pure and Mn2+ doped PVP films

Pure and Mn2+ ions doped (1 to 5 mol%) PVP polymer electrolytes were prepared by solution casting method by using double distilled water as a solvent. Thermogravimetric curves of the pure and Mn2+ doped polymer films show three distinct steps of weight loss. The Enhanced amorphous nature of PVP polymer film due to doping has been identified from X-ray diffraction analysis. SEM images appear the smoothest, uniform and homogenous surface, suggesting a good ordering structure. The optical band gaps of the films showed a decreasing trend with increasing dopant concentration. The FTIR spectra confirmed the complexation between the Mn2+ ions and the host polymer in terms of changes in intensity and certain bands position. The conductivity data, showed that 5 mol% Mn2+ doped PVP polymer electrolyte had shown maximum ionic conductivity of 3.21 × 10−8 S/cm at room temperature. From all the characterization results, 5mol% of Mn2+ ion-doped PVP polymer electrolyte exhibits better properties which are more suitable for fabricating solid-state batteries and other electrochemical devices.

Broadband dielectric spectroscopy of BMPTFSI ionic liquid doped solid-state polymer electrolytes: Coupled ion transport and dielectric relaxation mechanism

Broadband dielectric spectroscopy has been used to explore the charge carrier transport and relaxation mechanisms in different compositions of 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide doped poly(methylmethacrylate)-lithium bis(trifluoromethylsulfonyl)imide based solid polymer electrolytes. The free ion diffusivity and number density, which are directly linked with ion transport in ionic liquid based polymer electrolytes, are analyzed following the model of electrode polarization proposed by Macdonald–Trukhan. We have analyzed broadband dielectric spectra in terms of complex electric modulus formalism using two theoretical approaches such as Havrilliak–Negami and Kohlrausch–Williams–Watts functions. It has been observed that charge carrier diffusivity and dielectric relaxation time are strongly temperature dependent, following Vogel–Tammann–Fulcher behavior. It is also evident from the values of stretched exponent β that the relaxation behavior is highly non-exponential in these ionic liquid doped polymer electrolytes.

Energetics of Base-Acid Pairs for the Design of High-Temperature Fuel Cell Polymer Electrolytes.

The interaction energy of base-acid plays a key role in acid retention of phosphoric acid (PA)-doped polymer electrolytes under fuel cell operating conditions. Here, we investigate the energetics of proton-accepting and hydroxide-donating organic bases using density functional theory calculations. Because of their weak basicity, proton-accepting organic bases such as benzimidazole have relatively low interaction energy with the acid in the absence of water (15.3-28.0 kcal mol-1). Energetics of the proton-accepting base-PA complex increases by adding water, indicating that the interactions in the base-acid complex strengthen in the presence of water. On the other hand, hydroxide-donating organic bases, such as tetramethylammonium hydroxide, have high interaction energy with PA (∼110 kcal mol-1), which remains high in the presence of water. The chemical shifts of 31P NMR support the energetics of the base-acid complexes. This study further discusses the benefit of incorporating hydroxide-donating organic bases into the polymeric structure over proton-accepting bases as a way to increase acid retention.

Corn-starch based porous carbon and IL based electrolyte for high efficient supercapacitor

The corn-starch based porous carbon was synthesized using two step process and characterized. Also, a highly conducting ionic liquid doped polymer electrolyte was sandwiched between electrodes. The conductivity and specific capacitance of electrolyte and electrode of a capacitor was calculated using different characterization techniques.

PEO + NaSCN and ionic liquid based polymer electrolyte for supercapacitor

In this study, initially ion conducting solid polymer electrolyte films (SPEs) based on polyethylene oxide (PEO) and sodium thiocyanate (NaSCN) have been prepared using the standard solution cast technique. For further enhancement in the ionic conductivity value of optimized film, an ionic liquid (IL; 1-ethyl-3-methyl-imidazolium tricyanomethanide) ([EMIM][TCM]) has been incorporated in different weight ratios into the optimized polymer-salt complex matrix. The prepared SPEs are free-standing, flexible and exhibit good thermal and mechanical stabilities. Polarized optical microscopy (POM) shows a change in the surface morphology of IL doped polymer electrolyte films. The composition nature of polymer electrolyte films was confirmed using fourier transform infrared spectroscopy (FT-IR) via studying ion-ion and ion-polymer interactions. The FTIR studies confirm that complexation occurs between polymer-salt and polymer-salt-ionic liquid interactions. Polymer electrolyte films have been also characterized using X-Ray Diffraction (XRD). The structural analysis confirms that the intensity of crystalline peaks existing in solid polymer electrolyte films decreases after doping IL which enhances its amorphous nature. The thermal stability of different prepared electrolyte films has been investigated using thermogravinometric analysis (TGA). Ionic liquid doped polymer electrolyte films show more stable behavior than polymer host PEO and polymer-salt complex at high temperatures. IL doped polymer electrolyte film shows reduction in the degradation process with a residue mass of 29% at 400 °C. Polymer electrolyte films were also characterized using impedance spectroscopy (IS) to check their electrical properties. The maximum ionic conductivity is found to be 8.44 × 10−5 S cm−1 for 4 wt% IL doped solid polymer electrolyte film and the calculated value of ionic transference number (tion) for optimized electrolyte film is 0.98. Using this maximum ion-conducting polymer electrolyte film, we have developed a electrical double layer capacitor (EDLC). The calculated value of the specific capacitance of prepared EDLC is 1.07 Fg−1.

Preparation and Characterization of Ammonium Ceric Nitrate Doped PVDF Polymer Electrolytes

Poly [vinylidene fluoride] (PVdF): Ammonium ceric nitrate ((NH4)2Ce(NO3)6) based Proton conducting solid polymer electrolytes (SPEs) are prepared by solution casting technique. Polymer electrolytes are characterized by several techniques. The Structural property of the electrolytes are confirmed by XRD. The functional groups present in polymer electrolytes are confirmed by FTIR. The conductivity of the polymer electrolytes are calculated by using AC impedance analysis. The Maximum ionic conductivity is obtained for 2wt% of ammonium ceric nitrate doped polymer electrolyte.

Base-acid doped polybenzimidazole with high phosphoric acid retention for HT-PEMFC applications

A major problem faced by phosphoric acid doped polymer electrolyte membranes is leaking out easily as the reaction proceeds. Here, the long alkyl side chains with quaternary ammonium groups grafted the polybenzimidazole membranes (PBI-Sc-X) are prepared. The strong interaction between quaternary ammonium and biphosphate ion-pairs keep phosphoric acid (PA) in base-acid doped membranes. As a result, the remaining PA weight of PBI-Sc-X membranes could hold above 80%, which is better than that of pure PBI. Besides, it is observed that the highest power density of 411.7 mW/cm2 at 160 °C under current density 1000 mA/cm2 is obtained with base-acid doped PBI-Sc-5 membranes. Furthermore, the PBI-Sc-X membranes show considerable performance in oxidative stability, mechanical strength and thermal stability, which gave a basis for HT-PEMFCs application.

Optical and Conductivity Studies of Cr3+ Doped Polyvinyl Pyrrolidone Polymer Electrolytes

Polymer electrolyte films of polyvinyl pyrrolidone (PVP) embedded with various concentrations of Cr3+ ions were prepared by a solution casting technique. The complexation between the Cr3+ ions and the polymer was confirmed by Fourier transform infrared (FTIR) spectroscopy and UV–vis spectroscopy. The electrical conductivity of the films was measured using an impedence analyzer in the frequency range of 42 Hz to 5 MHz at ambient temperature. It was observed that the conductivity increased with the increase in the Cr3+ ion concentration. UV–visible absorption spectra in the wavelength range of 200–800 nm were used to determine the direct and indirect optical energy band gaps and optical absorption edge. Both of the optical band gaps decreased with the increase in Cr3+ ion concentration. FTIR studies on pure and Cr3+ doped PVP polymer films revealed the vibrational changes that occurred due to the effect of the dopant Cr3+ ions in the polymer. Our results suggested that Cr3+, as a dopant, is a good choice to improve the electrical properties of PVP polymer electrolytes.

Investigation on the Effect of Nitrogenous Compound Benzotriazole on the Structural, Thermal and Dielectric Properties of PEO-PMMA Blended Polymer Electrolyte System and Its Performance in Dye Sensitized Solar Cells

The present study reports on the performance of organic nitrogenous compound namely, benzotriazole (BTZ) in polyethylene oxide (PEO)-poly(methylmethacrylate) matrix in conjunction with potassium iodide and iodine as a blended polymer electrolyte and its application in TiO2 nanocrystalline solar cells. On comparison of electrical conductivity between five different compositions of benzotriazole, polymer matrix with 0.005 M of benzotriazole exhibited the best ionic conductivity with 1×10-5 Scm-1. The photochemical properties of the best conducting sample showed an open circuit voltage (Voc) of 7.4 V, short circuit current density (Jsc) of 6.74 mA, fill factor of 0.73 and efficiency (η) of 3.6%. The structural modifications in these doped polymer electrolyte were analysed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The complex impedance and dielectric analyses were carried out to completely understand the relevent ion conduction mechanism.

Li+ doped chitosan-based solid polymer electrolyte incorporated with PEDOT:PSS for electrochromic device

In this study, solid polymer electrolyte (SPE) based on chitosan (Ch) was prepared with addition of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), lithium trifluro methane sulfonate (LiTRIF), propylene carbonate (PC) by solvent casting technique. The chitosan-based polymer electrolyte was characterized using electrochemical impedance spectroscopy (EIS). The ionic conductivity value was calculated as 4.2 x 10-4 S/cm. The SPE having good ionic conductivity was used to fabricate electrochromic device with glass/ITO/WO3׀PEDOT:PSS-Ch-LiTRIF-PC׀ITO/glass whose performance was evaluated via cyclic voltammetry, transmittance, repeating chronoamperometry. The optical contrast of ECD was attained as 22% at 800 nm, which resulting in coloration efficiency of 67 cm2/C. The ECD displays fast response time for coloration (tc ) is 0.29 s. Upon reversal of potential bleaching (tb ) forms within 3 s. The findings demonstrated that this SPE electrolyte has promising candidate for use in optoelectronic applications.

PVDF-HFP and 1-ethyl-3-methylimidazolium thiocyanate–doped polymer electrolyte for efficient supercapacitors

The sole aim of the present article is to develop an ionic liquid (IL)-doped solid polymer electrolyte for an electrochemical double-layer capacitor (EDLC). A solution cast technique was adopted to develop a solid polymer electrolyte of poly (vinylidene fluoride-co-hexafluoropropylene) as host polymer and low-viscosity IL (1-ethyl-3-methylimidazolium thiocyanate) as dopant. Electrochemical impedance spectroscopy measurement showed a six orders of magnitude enhancement in conductivity ( σ) by IL doping. A linear sweep voltammetric investigation of the electrolyte films exhibited a good electrochemical stability window of 3.6 V. Polarized optical microscopy of the synthesized films revealed a reduction in crystallinity by IL doping. Infrared spectroscopy further affirms the composite nature of the film. The maximum conductivity value of 2.65 mS/cm is obtained for 80% of the ionic-doped system. Using maximum conductivity film and porous carbon-based electrodes, we have developed EDLCs that show a specific capacitance value of 2.36 F/g.

Electrical and structural properties of multi-walled carbon nanotube–doped polymer electrolyte for photo electrochemical device

The present investigation deals with the preparation of multi-walled carbon nanotube (MWCNT)-doped plasticized polymer electrolyte. The nanocomposite has been prepared using solution casting method. Complex impedance spectroscopy study revealed the utmost room temperature conductivity of 5.6 × 10−4 S/cm when optimized plasticized polymer electrolyte (poly(ethyl methacrylate)+30% sodium iodide+60% ethylene carbonate) was doped with 7% MWCNT. Temperature dependence of conductivity showed Arrhenius behavior. The surface morphology and crystalline–amorphous deviation of the composite was observed using scanning electron microscope. Perfect complexation of various components of the composite was confirmed from Fourier-transform infrared spectroscopy and X-ray diffraction (XRD) data. The transference number measurement was done to calculate the proportionate amount of ionic and electronic conductivity. A dye sensitized solar cell has been fabricated using maximum ionic conductivity of solid polymer electrolyte and its electrical parameters measured at 1 sun condition.

Preparation and characterizations of PMMA-PVDF based polymer composite electrolyte materials for dye sensitized solar cell

Blend polymer composite gel electrolytesare prepared using thepoly vinyledene fluoride (PVDF), polymethyl methacrylate (PMMA) with alumina (Al2O3) in variance of alkali metal iodide saltsystem. The alumina doped blend polymer electrolytes characterized by the XRD diffraction and FT-IR spectra. This is supportive to the conformation of the crystallinity behaviour and the composite formation.The high-resolution scanning electron microscopy (HR-SEM) have used to find the composite electrolyte membrane porous size (10 μm) and it has support to understand the morphological structure of the membrane. To analyze the ionic conductivity of the potassium iodide based composite polymer electrolyte by the impedance measurements, which is 4.62 × 10−3 Scm−1 at room temperature. Finally, different alkali metal iodide based dye-sensitized solar cells (DSSCs) fabricated and monitored an energy conversion efficiency.

Synthesis, electrolyte properties and solar cell performance of hyperbranched poly(aryl-ether-urea)s

ABSTRACTHyperbranched poly(aryl-ether-urea)s with phenyl, N,N-dimethylamino ethyl and polyethylene oxide end-groups linked through urethane group – HBPEU-1, HBPEU-2 and HBPEU-3 respectively – were synthesized from an AB2-type blocked isocyanate monomer and characterized by FT-IR, 1H-NMR, SEC-MALLS, TGA and DSC techniques. The molecular weight of the polymers were found to be ranged from 4.9 × 103 − 1.96 × 104 g/mol. The TGA results showed that the polymers decompose between 175°C – 220°C. In the DSC curves, HBPEU-1 and HBPEU-3 showed Tg at 160°C and 53°C respectively, whereas HBPEU-2 did not showed clear Tg. All the three polymers were converted into polymer electrolytes by doping with LiI/I2. The doped polymers showed remarkably high ionic conductivity, up to 222 – 277 times compared to the un-doped polymers and the highest conductivity was observed with doped HBPEU-2. The TiO2 based dye-sensitized solar cells (DSSCs) were fabricated using the doped polymer electrolytes and their performance was tested; HBPEU-2 showed good performance by yielding energy conversion efficiency (η) of 4.5%.

Star poly(4-vinylpyridine)s using dendritic ATRP initiators: Synthesis, electrolyte property and performance in dye sensitized solar cell

The G0 and G1 polyurethane dendrimers terminated with 3–12 atom transfer radical polymerization (ATRP) initiators were prepared using single and dual functional ATRP reagents and their structures were confirmed using FT-IR, 1H–NMR, HR-MS and SEC-MALLS techniques. 4-Vinylpyridine was polymerized using the G1 dendritic initiators to obtain six- and twelve-arm star poly(4-vinylpyridine)s (STAR-P1 and STAR-P2). The absolute molecular weight and PDI of star polymers were in the order of 105 and 1.23–1.24 respectively. Hydrolysis leading to degradation of inner polyurethane core of the star polymers yielded more narrow dispersed poly(4-vinylpyridine) chains and the SEC-MALLS data of these chains confirm the accurate control on number of arms. Both of the polymers were doped with KI/I2 along with N3-dye to work as efficient polymer electrolytes for dye sensitized solar cell (DSSC). The increment in the conductivity of doped STAR-P1 was very significant and reached 2.415 mS/m from 0.0066 mS/m of dopant salt. The current-voltage characteristics of these doped polymer electrolytes measured under simulated sun light with AM 1.5 at 40 mW/cm2 yielded energy conversion efficiency (η) of 5.13% and 1.90% for STAR-P1 and STAR-P2 respectively and these values also significantly high compared to 1.09% corresponds to current-voltage curve of the device fabricated without the polymers.

Mediator Effects on Solid-State Mediator Doped Polymer Electrolyte Membrane

Electrolyte and separator are two vital components in supercapacitors. High safety is one of the major advantages of polymer electrolyte, which means, even in extreme environment or during faulty, polymer electrolyte will not release any harmful gas or liquid. Mediators are a pair of compounds which can reciprocal transform by losing and gaining electrons. Thus, doping mediators in polymer electrolyte will improve the electronic conductivity. Use of the mediator doped electrolytes in the electrode matrix will benefit the transport process in supercapacitors. However, these electrolytes should not be used in the separators. Polyvinylidene fluoride (PVDF) and lithium trifluoromethanesulfonate (LiTFS) was selected as polymer electrolyte. One mediator couple are potassium ferrocyanide (K3Fe(CN)6) and potassium ferricyanide (K4Fe(CN)6). Another couple are iodine (I2) and sodium iodide (NaI). Conductivity of the membranes were measured with an device as shown in Figure 1. Results of electronic conductivity versus the concentration of mediators are given in Figure 2 and results of ionic conductivity versus the concentration of mediators are given in Figure 3. Electronic conductivity of membranes is enhanced from 10-7 S/cm level to 10-4 S/cm level by increasing the concentration of mediators from 0% to 5%. In the I2/NaI mediator doped membrane the electronic conductivity continuously increase with increasing the concentration above 5%. However, in the K3Fe(CN)6/ K4Fe(CN)6. doped membrane the electronic conductivity is a constant above 5%. Ionic conductivity of membranes is stayed on 10-2 S/cm level. The authors use the electron exchange mechanism and site percolation theory to explain the phenomenon. Figure 1

Lithium ion-conducting polymer electrolytes based on PVA–PAN doped with lithium triflate

Blend polymer electrolytes with optimized composition (92.5 PVA:7.5 PAN) doped with lithium triflate (LiCF3SO3) have been prepared in different concentrations by solution casting technique, using DMF as solvent. The prepared electrolytes have been characterized by XRD, FTIR, DSC, AC impedance, and SEM techniques. The complex formation between the blend polymer and the salt has been confirmed by X-ray diffraction and FTIR analyses. Differential scanning calorimetry thermogram has shown a decrease in glass transition temperature with the addition of salt. It has been observed that the ionic conductivity of the doped blend polymer electrolyte increases as the salt concentration increases. The ionic conductivity has been found to be 4.0 × 10−5 S cm−1 for 92.5 PVA:7.5 PAN:50 M wt% LiCF3SO3 sample at room temperature. The temperature dependence of ionic conductivity has been studied with Arrhenius plot and the activation energies have been calculated. Primary lithium ion battery has been constructed with the configuration Zn + ZnSO4 7H2O/ 92.5 PVA:7.5 PAN:50 M wt% LiCF3SO3/ PbO2 + V2O5 using the maximum conducting blend polymer, and its discharge characteristics have been studied.