Electrochemical Properties Of Poly Research Articles

The physical and electrochemical properties of poly(vinylidene chloride-co-acrylonitrile)-based polymer electrolytes prepared with different plasticizers

Lithium ion-conducting membranes with poly(ethylene oxide) (PEO)/poly(vinylidene chloride-co-acrylonitrile) (PVdC-co-AN)/lithium perchlorate (LiClO4) were prepared by solution casting method. Different plasticizers ethylene carbonate (EC), propylene carbonate (PC), gamma butyrolactone (gBL), diethyl carbonate (DEC), dimethyl carbonate (DMC), and dibutyl phthalate (DBP) were complexed with the fixed ratio of PEO/PVdC-co-AN/LiClO4. The preparation and physical and electrochemical properties of the gel polymer electrolytes have been briefly elucidated in this paper. The maximum ionic conductivity value computed from the ac impedance spectroscopy is found to be 3 × 10−4 S cm−1 for the EC-based system. From DBP-based system down to EC-based system, a decrease of crystallinity and an increase of amorphousity are depicted by X-ray diffraction technique, the decrease of band gap energy is picturized through UV–visible analysis, the decrease of glass transition temperature is perceived from differential scanning calorimetry plots, and the reduction of photoluminescence intensity is described through photoluminescence spectroscopy study at an excitation wavelength of 280 nm. Atomic force microscopic images of EC-based polymer electrolyte film show the escalation of micropores. Fourier transform infrared spectroscopy study supports the complex formation and the interaction between the polymers, salt, and plasticizer. The maximum thermal stability is obtained from thermogravimetry/differential thermal analysis, which is found to be 222 °C for the sample complexed with EC. The cyclic voltagram of the sample having a maximum ionic conductivity shows a small redox current at the anode, and cathode and the chemical stability is confirmed by linear sweep voltammetry.

레이온/폴리에틸렌옥사이드 분리막과 하이드로겔 전해질이 적용된 활성탄 수퍼커패시터 특성

Rayon 분리막에 poly(ethylene oxide) (PEO)를 코팅하고 potassium polyacrylate (PAAK)-KOH 하이드로겔 전해질을 사용하여 기계적 강도 및 전기화학적 성질을 시험하였고, 이를 활성탄 수퍼커패시터에 적용하여 커패시터 특성을 조사하였다. PEO 코팅량의 증가에 따라 기계적 강도는 증가하였으며, PEO 함량을 5 wt.% 이하로 유지하면 이온전도도가 <TEX>$10^{-2}S\;cm^{-1}$</TEX> 이상을 유지하여 실제 커패시터에의 활용이 가능하였다. 결과적으로 Rayon/PEO 분리막과 PAAK/KOH 전해질을 적용한 활성탄 수퍼커패시터는 <TEX>$1000mV\;s^{-1}$</TEX>의 높은 스캔속도에서도 비축적용량이 1000 사이클까지 안정하게 나타나는데, 이는 PEO 코팅이 Rayon의 장섬유 필라멘트간 엉킴점을 고정시켜 고출력 안정성을 얻을 수 있기 때문이다. The mechanical and electrochemical properties of poly(ethylene oxide) (PEO)-coated Rayon separator were characterized using potassium polyacrylate (PAAK)-KOH electrolyte. The supercapacitive properties of activated carbon supercapacitor adopting the Rayon/PEO separator and PAAK-KOH electrolyte was also tested. As the PEO content increased, the mechanical strength increased. Room-temperature ionic conductivity of over <TEX>$10^{-2}S\;cm^{-1}$</TEX> was obtained at the PEO content lower than 5 wt.%, applicable to a supercapacitor. As a result, the specific capacitance at <TEX>$1000mV\;s^{-1}$</TEX> of the activated carbon supercapacitor adopting the Rayon/PEO separator and PAAK-KOH electrolyte was highly stable after 1000th cycle. This was due to high rate-capability provided by the fact that PEO coating could fix the entanglements among fiber filaments of Rayon.

Synthesis and electrochemical properties of poly (2-ethynylpyridine) functionalized graphene nanosheets

A straightforward and efficient approach was demonstrated for the synthesis of an ionic conjugated, reduced graphene oxide/poly (2-ethynylpyridinium) (RGO/P2EP) hybrid via covalent bond chemistry. Graphene oxide (GO) were treated with thionyl chloride to yield acylated GO (GOCOCl), which was subsequently used to activate the polymerization of 2-ethynylpyridine (2-EPy). FTIR and XPS results revealed that 2-EPy was successful polymerized in the presence of GOCOCl and covalently attached onto the surfaces of GO sheets. The XRD and FESEM results indicated that GO sheets were encapsulated in the P2EP matrix. The as-obtained hybrid exhibited an excellent dispersion in water. When evaluated as an electrode material for supercapacitors, the RGO/P2EP hybrid exhibited a high specific capacitance of 225Fg−1 at the current density of 0.5Ag−1, remarkable rate capability, and excellent cycling performance with the capacitance retention of ∼94% after 1000 cycles. The enhanced electrochemical property can be attributed to the synergetic effect and strong interfacial interaction at the interface of RGO/P2EP.

The structure and electrochemical properties of poly(3,4-propylenedioxythiophene)/SnO2nanocomposites synthesized by mechanochemical route

In this study, the poly(3,4-propylenedioxythiophene)/SnO2 nanocomposites (PProDOT/SnO2) with different contents of SnO2 were successfully prepared by using hand grinding and ball milling methods, respectively. The effects of the synthesis methods and SnO2 on the structure and electrochemical properties of the nanocomposites were deeply discussed. The results showed the structure of composites were highly affected by the increasing amount of nano-SnO2 particles in reaction medium of hand grinding method than ball milling method. And, the PProDOT/SnO2 nanocomposites from ball milling method displayed similar absorption spectra, and ball milling method promoted the uniform distribution of nano-SnO2 particles in PProDOT matrix. However, PProDOT/SnO2 nanocomposites from hand grinding method displayed the higher specific surface area and stronger synergetic effects between PProDOT and SnO2 than that of PProDOT/SnO2 nanocomposites from ball milling method. As a result, the PProDOT/SnO2 nanocomposites from hand grinding method showed higher electrochemical activity than PProDOT/SnO2 nanocomposites from ball milling method. Moreover, the specific capacitance and cycle stability of PProDOT/SnO2 nanocomposites from both methods were higher than respective pure PProDOT. Among all the nanocomposites, PProDOT/15wt%SnO2 nanocomposite from hand grinding method possessed the highest specific capacitance (259 F g−1) with the best cycle performance (capacitance retention of 82% after 1,000 cycles). POLYM. COMPOS., 37:2884–2896, 2016. © 2015 Society of Plastics Engineers

Electrochemical properties of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) and carbon black composite as an electron injector into the electrolyte containing iodide redox couple

A composite of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) polymer and carbon black powder (P/CB composite) is studied as an electron injector into the electrolyte of iodide redox couple in dye-sensitized solar cells (DSCs) replacing conventional platinum layer. P/CB composite films are coated with spin coating method on fluorine-doped tin oxide layer on glass substrate. The connectivity between carbon black powder is substantially improved with the addition of conducting PEDOT:PSS polymer which reduces the charge transport resistance through the composite layer. Post deposition thermal and acid treatments enhance the conductivity and connectivity. The charge transfer resistance at the electrolyte and P/CB composite electrode interface is also reduced because both PEDOT:PSS and carbon black act as a catalyst for the reduction of I3− into I−. The charge transfer resistance is increased, however, when the amount of PEDOT:PSS is higher than 20wt% because most of pores between carbon black powder are filled with PEDOT:PSS to reduce the interface area. The thickness of P/CB composite layer is optimized and an electrochemical circuit model is applied along with the electrochemical impedance measurement to explain the electrochemical behavior of this composite layer. A DSC made of 4.5μm thick P/CB composite layer with 17wt% PEDOT:PSS shows high performance (efficiency: 7.4%) which is comparable to Pt-based DSCs (efficiency: 7.7%). Furthermore, the P/CB composite can serve as a catalytic electrode on both bare glass and PET sheets, and DSCs with these FTO-free electrodes show high efficiencies >7.0%. Thus, the P/CB composite would open new prospects for realizing a printing process with flexible substrates at low temperature.

Effect of zwitterions on electrochemical properties of oligoether-based electrolytes

Solid polymer electrolytes show great potential in electrochemical devices. Poly(ethylene oxide) (PEO) has been studied as a matrix for solid polymer electrolytes because it has relatively high ionic conductivity. In order to investigate the effect of zwitterions on the electrochemical properties of poly(ethylene glycol) dimethyl ether (G5)/lithium bis(fluorosulfonyl) amide (LiFSA) electrolytes, a liquid zwitterion (ImZ2) was added to the G5-based electrolytes. In this study, G5, which is a small oligomer, was used as a model compound for PEO matrices. The thermal properties, ionic conductivity, and electrochemical stability of the electrolytes with ImZ2 were evaluated. The thermal stabilities of all the G5-based electrolytes with ImZ2 were above 150°C, and the ionic conductivity values were in the range of 0.8–3.0mScm−1 at room temperature. When the electrolytes contained less than 5.5 wt% ImZ2, the ionic conductivity values were almost the same as that of the electrolyte without ImZ2. The electrochemical properties were improved with the incorporation of ImZ2. The anodic limit of the electrolyte with 5.5 wt% ImZ2 was 5.3V vs. Li/Li+, which was over 1V higher than that of G5/LiFSA.

The effects of SiO2 and TiO2 nanofillers on structural and electrochemical properties of poly(ethylene oxide)–EMIHSO4 electrolytes

The effects of SiO2 and TiO2 nanofillers on a poly(ethylene oxide) (PEO)–1-ethyl-3-methylimidazolium hydrogensulfate (EMIHSO4) electrolyte were studied and compared with respect to ionic conductivity, crystallinity, and dielectric properties over a temperature range from −10°C to 80°C. X-ray diffraction and differential scanning calorimetry were used to study the impact of fillers on the structure of the polymer electrolytes. Using an electrochemical capacitor model, impedance (complex capacitance) and dielectric analyses were performed to understand the ionic conduction process with and without fillers in both semi-crystalline and amorphous states. Despite their different nanostructures, both SiO2 and TiO2 promoted an amorphous structure in PEO–EMIHSO4 and increased the ionic conductivity by a factor of two. While in the amorphous phase, the dielectric constant characteristic of the fillers (TiO2 in this case) contributed to increased conductivity and cell capacitance. Combining complex capacitance and dielectric analyses is an effective approach to study solid electrochemical capacitors and to identify and explain the impact of different fillers on ionic conduction of polymer electrolytes.

Complementary study on the electrical and structural properties of poly(3-alkylthiophene) and its copolymers synthesized on ITO by electrochemical impedance and Raman spectroscopy

Targeting the use of organic conjugated polymers in organic solar cells, this study looks at the electrochemical properties of poly(3-alkylthiophene) films: poly(3-methylthiophene), poly(3-hexylthiophene), poly(3-octylthiophene) and its copolymers electrochemically synthesized on a tin-doped indium oxide (ITO) substrate. Electrochemical impedance spectroscopy (EIS) was used to monitor the change in the electrochemical behavior of these films on the ITO and the charge transfer resistance (RCT) values were determined in open circuit potential (OCP) and at different overpotentials. Together with the EIS, the ex situ and in situ Raman spectroscopy was used to characterize the influence of aromatic radical cation and dication species, present in the polymer matrix of homo and copolymers, in the management processes seen in the Nyquist and Bode-phase diagrams for different systems obtained on ITO. The EIS results in OCP showed an decrease in resistance demonstrating increased conductivity with the copolymerization, and through the Bode-phase diagram and the ex situ Raman spectra, these changes were related to the oscillation of the radical cation and dication along the polymer matrix. By studying Nyquist and Bode-phase diagrams in the overpotentials, an increase in RCT values in higher potentials was seen that could be related to the bipolaronic process, which after the deconvolution of the in situ Raman spectra, was possible to relate these results to the stabilization of the dication species in the homo and copolymers matrix when subjected to high potential.

Synthesis and characterization of an ionic conjugated polymer: poly[2-ethynyl-N-(2-furoyl)pyridinium chloride

A new ionic polyacetylene derivative with furoyl substituents was prepared by the uncatalyzed polymerization of 2-ethynylpyridine by using 2-furoyl chloride in high yield. The polymer structure was characterized by such instrumental methods as NMR, IR, and UV-visible spectroscopies to have a polyacetylene backbone system with the N-(2-furoyl)pyridinium chloride. The electro-optical and electrochemical properties of poly[2-ethynyl-N-(2-furoyl)pyridinium chloride [PEFPC] were studied. The photoluminescence spectrum showed that the PL peak is at 578 nm corresponding to the photon energy of 2.15 eV. The cyclovoltammograms of PEFPC exhibited the irreversible electrochemical behaviors between the oxidation and reduction peaks. The oxidation current density of polymer versus the scan rates is approximately linear relationship in the range of 30 mV/sec-150 mV/sec. It was found that the kinetics of redox process is controlled by the reactant diffusion process from the oxidation current density of PEFPC versus the scan rates.

Electrochemical Properties of Poly(Anthraquinonyl Sulfide)/Graphene Sheets Composites as Electrode Materials for Electrochemical Capacitors.

Poly(anthraquinonyl sulfide) (PAQS)/graphene sheets (GSs) composite was synthesized through in situ polymerization to evaluate its performance as an electrode material for electrochemical capacitors. PAQS was successfully synthesized in the presence of GSs with uniform distribution. PAQS/GSs showed a pair of reversible redox peaks at around 0 V (vs. Ag/AgCl). The specific capacitance of PAQS/GSs was 349 F·g−1 (86 mAh·g−1) at a current density of 500 mA·g−1, and a capacitance of 305 F·g−1 was maintained even at a high current density of 5000 mA·g−1. The in situ polymerization of PAQS with GSs facilitated their interaction and enabled faster charge transfer and redox reaction, resulting in enhanced electrode properties.

Structure and electrochemical properties of track membranes with a polymer layer obtained by plasma polymerization of acetylene

The structure and electrochemical properties of poly(ethylene terephthalate) track membrane modified by acetylene plasma were studied. It was found that polymer deposition on the surface of a track membrane by plasma polymerization of acetylene results in the creation of composite membranes that, in the case of formation of a thin semipermeable layer, possess an asymmetry of conductivity in electrolyte solutions – a rectification effect. It is caused by the reduction of the pores diameter due to the plasma polymer that results in changing the pore geometry, and as well due to the existence of an interface between the initial membrane and the polymer layer which have various concentrations of carboxyl groups.

Electrochemical impedance spectroscopy study of poly[3,5-dithiophene-2-yldithieno[3,2-b;2′,3′-d]thiophene] P(Th2DTT)

Electrochemical properties of poly[3,5-dithiophene-2-yldithieno[3,2-b;2′,3′-d]thiophene] film was investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) for the applicability of the system as an electrochemical capacitor. 3,5-Dithiophene-2-yldithieno[3,2-b;2′,3′-d]thiophene (Th2DTT) was electropolymerized on Pt electrodes with varying thicknesses in two different potential ranges, which provided the polymer films with different structures. Impedance spectra of the films were obtained at dc potentials where they were in the oxidized (p-doped) states. The EIS data were fitted to an equivalent electrical circuit to characterize the electrochemical properties of the electrodes. A good agreement was achieved with the experimental and simulated EIS data. These results imply that the polymeric films provide enhanced capacitance, which make them promising materials in energy-storage devices.

Synthesis and electrochemical properties of poly(2,3‐dimethylaniline)/polyaniline composites

In this study, poly(2,3‐dimethylaniline)/polyaniline (P(2,3‐DMA)/PANI) composite was prepared by in situ polymerization of aniline on the surface of P(2,3‐DMA) particles in hydrochloric acid solution. Fourier transform infrared spectra and X‐ray diffraction results of the composites indicated that P(2,3‐DMA) was successfully modified by PANI. The electrochemical activity and electrical conductivity of the P(2,3‐DMA)/PANI composite were discussed by cyclic voltammetry and standard four‐probe tests, respectively. The results showed that the conductivity of the composite increased with the increasing aniline concentration, which can expand the potential applications of P(2,3‐DMA), such as use in anti‐static coatings or electronic devices. The P(2,3‐DMA)/PANI composite also showed better solubility and anticorrosive property than PANI. POLYM. COMPOS., 36:1541–1545, 2015. © 2014 Society of Plastics Engineers

Electrochemical properties of poly(4,4′-diaminodiphenyl sulfone) as a cathode material of lithium secondary batteries

Doped poly(4,4′-diaminodiphenyl sulfone) (pDDS) is prepared for use as a cathode-active material of lithium secondary batteries by chemical oxidation method using ammonium persulfate initiator. The synthesized pDDS and doped pDDS are characterized by chemical structure analysis using Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Cyclic voltammetry shows that the doped pDDS has a typical pair of redox peaks at 3.75/3.15 V vs. Li/Li+, corresponding to charging/discharging of the lithium ion. The discharge capacity at low current rate (0.05 C-rate) achieves 31.5 and 24.3 mA h g−1 in the initial and 50th cycles, respectively. The doped pDDS also shows good cycle performance and high-rate capability, making it appropriate as a cathode material of lithium secondary batteries.

Effect of poly(ethylene oxide) on ionic conductivity and electrochemical properties of poly(vinylidenefluoride) based polymer gel electrolytes prepared by electrospinning for lithium ion batteries

Effect of poly(ethylene oxide) on the electrochemical properties of polymer electrolyte based on electrospun, non-woven membrane of PVdF is demonstrated. Electrospinning process parameters are controlled to get a fibrous membrane consisting of bead-free, uniformly dispersed thin fibers with diameter in the range of 1.5–1.9 μm. The membrane with good mechanical strength and porosity exhibits high uptake when activated with the liquid electrolyte of lithium salt in a mixture of organic solvents. The polymer gel electrolyte shows ionic conductivity of 4.9 × 10−3 S cm−1 at room temperature. Electrochemical performance of the polymer gel electrolyte is evaluated in Li/polymer electrolyte/LiFePO4 coin cell. Good performance with low capacity fading on charge–discharge cycling is demonstrated.

Electrical and electrochemical properties of poly (methyl methacrylate) based nanocomposite gel electrolytes dispersed with dedoped (insulating) polyaniline nanofibers

In this work, we have investigated the effect of dedoped (insulating) polyaniline (PAni) nanofibers on the electrical and electrochemical properties of poly(methyl methacrylate) (PMMA)-based gel electrolytes. PAni nanofibers have been synthesized using interfacial polymerization technique. By analysis of X-ray diffraction (XRD) and impedance spectroscopy results, it has been demonstrated that the incorporation of dedoped PAni nanofibers up to a moderate concentration (4 wt%) to PMMA–(PC + DEC)–LiClO4 gel polymer electrolyte system significantly enhances the ionic conductivity of the electrolyte system, which can be attributed to the inhibition of polymer chain reorganization upon dispersion of high aspect ratio nanofibers in PMMA matrix resulting in reduction in polymer crystallinity, which gives rise to an increase in ionic conductivity. At higher concentration, dedoped nanofibers appear to get phase separated and form insulating clusters, which impede ionic transport. The phase separation phenomena at higher fraction of nanofibers are confirmed by XRD. Studies on electrochemical behavior reveal that electrochemical potential window increases with the increase of nanofibers loading.

Characterization and electrochemical properties of poly(aniline-co-o-methoxyaniline)/multi-walled carbon nanotubes composites synthesized by solid-state method

The composites of copolymers of aniline (An) and o-methoxyaniline (OMA) with multi-walled carbon nanotubes, named as copolymers/MWNT, (poly(An-co-OMA)/MWNT) were prepared by solid-state synthesis method at room temperature. The homopolymers/MWNT composites were synthesized for comparison. The structure and morphology of these composites were characterized by FT-IR spectroscopy, UV-Vis absorption spectroscopy, X-ray diffraction (XRD) and TEM. The electrochemical performances of the composites were investigated by galvanostatic charge-discharge, cyclic voltammetry (CV) and cycle life measurements. The results from FT-IR and UV-Vis spectra showed that different molar ratio of [An]/[OMA] in reaction system has great influence on the oxidation degree, conjugation length and doping level of the copolymers in these composites. The presence of MWNT in the composites was confirmed from the characteristic peaks of MWNT in XRD patterns and the enwrapped MWNT in TEM images. The TEM images further indicates that the MWNT uniformly distributed and enwrapped with polymer in the case of composite from molar ratio of [An]/[OMA]=1:1. The results also showed that the morphology, crystallinity and solubility of composites were highly affected by the incorporation of OMA unit copolymer chain. The results from electrochemical performances suggested that the molar ratio of [An]/[OMA]=3:1 in reaction system can make the obtained composites displayed a higher specific capacitance, good rate ability and cycling stability.

架橋ジフェニルアミン系ポリマーの電気化学特1性における化学構造の効果の探索

架橋ジフェニルアミン系ポリマーの電気化学特1性における化学構造の効果の探索

Effect of nano-clay on ionic conductivity and electrochemical properties of poly(vinylidene fluoride) based nanocomposite porous polymer membranes and their application as polymer electrolyte in lithium ion batteries

Hybrid organic–inorganic polymer gel electrolytes (PGEs) based on polymer–clay nanocomposite microporous membrane containing 1M lithium hexafluorophosphate (LiPF6) in ethylene carbonate/diethyl carbonate (EC/DEC) are fabricated and their electrochemical characteristics in lithium ion batteries are studied. Poly(vinylidene fluoride) (PVdF)–clay nanocomposite membrane containing different clay loading are prepared by phase inversion method. Aqueous suspension of montmorrillonite (MMT) clay in dimethyl acetamide (DMAc) is used as the nano-clay. The morphology of the clay dispersion with sonication time is studied by environmental scanning electron microscope (E-SEM). The intercalation/exfoliation of polymer–clay nanocomposite is characterized by X-ray diffraction (XRD). Differential scanning calorimetry (DSC) and thermal gravimetric analysis are used for the evaluation of thermal properties. DSC analysis shows that crystallinity of nanocomposite decreases with increasing nano-clay content. The effect of clay on the membrane morphology, ionic conductivity and electrochemical properties of the PGEs in lithium ion rechargeable batteries are studied and results are compared. Incorporation of 2wt.% nano-clay in PGE enhances its ionic conductivity from 0.78 to 3.08mScm−1 at room temperature. Li-ion half cell comprising of Li/PVdF–clay(2wt.%)-PGE/LiMn2O4 delivers high charge–discharge capacity (∼120mAhg−1) and shows stable cycle performance.

Electro-optical and Electrochemical Properties of a Disubstituted Polyacetylene: Poly(1-phenyl-2-trimethylsilylacetylene)

The electro-optical and electrochemical properties of poly(1-phenyl-2-trimethyl silylacetylene), which is a disubstituted polyacetylene with bulky phenyl and trimethylsilyl groups as substituents, were studied. The photoluminescence (PL) spectra of polymer showed that the photoluminescence peaks are located at 484 and 532 nm, corresponding to a photon energy of 2.56 and 2.33 eV, respectively. The cyclic voltamograms of the polymer exhibited reversible electrochemical behaviors between the doped and undoped peaks. It was found that the kinetics of the redox process of polymer is controlled by the reactant diffusion process.