Electrochemical Study Of Poly Research Articles

Alkali‐Metal‐Ion Batteries: Electrochemical Study of Poly(2,6‐Anthraquinonyl Sulfide) as Cathode for Alkali‐Metal‐Ion Batteries (Adv. Energy Mater. 48/2020)

Alkali‐Metal‐Ion Batteries: Electrochemical Study of Poly(2,6‐Anthraquinonyl Sulfide) as Cathode for Alkali‐Metal‐Ion Batteries (Adv. Energy Mater. 48/2020)

Electrochemical Study of Poly(2,6‐Anthraquinonyl Sulfide) as Cathode for Alkali‐Metal‐Ion Batteries

AbstractOrganic electrode materials are extensively applied for alkali metal (lithium, sodium, and potassium)‐ion batteries (LIBs, SIBs, and PIBs) due to their sustainability and low cost. As a typical organic cathode, poly(2,6‐anthraquinonyl sulfide) (PAQS) shows high theoretical capacity, yet its electrochemical behavior and mechanisms in alkali‐metal‐ion batteries still require clarification. Herein, PAQS microspheres are synthesized and applied as cathodes for LIBs, SIBs, and PIBs. When using traditional low‐concentration electrolytes, the reduction voltage and the initial discharge capacity of PAQS electrode in LIB, SIBs, PIBs are 2.11 V/103 mAh g−1, 1.76/1.30 V/134 mAh g−1, 1.94/1.54 V/198 mAh g−1 at 100 mA g−1, respectively, while the cycling stability of PAQS is in the order of LIBs > SIBs > PIBs. To further promote the practical application of PIBs, a facile method is demonstrated to improve the cycle stability of PAQS for PIBs by using a novel high‐concentration electrolyte. The cycling stability of PIBs with PAQS can be improved significantly to 1200 cycles with a capacity decay of 0.031% per cycle. This work may provide guidelines for developing innovative organic materials used in applicable metal‐ion batteries demonstrates the impact of electrolyte optimization on improving the cycling stability.

Electrochemical Study of Poly(aryloxyphosphazenes) Functionalized with COOH and NO2 Groups. In Search of New Applications

An electrochemical study of poly(aryloxyphosphazenes) substituted with COOH and NO2 groups is reported here for the first time. In order to develop new applications, a glassy carbon electrode was coated with the compound in non-aqueous media, and it behavior was studied using Cyclic Voltammetry, Differential Pulse Voltammetry and Electrochemical Impedance Spectroscopy techniques. The analysis showed that the current intensity of the electrochemical response increases when the substitution degree in COOH− as NO2−functionalized poly(aryloxyphosphazenes) increases, therefore is it possible to predict the degree of substituent for this kind of polymer. Subsequently the morphology of glassy carbon electrodes modified with COOH− and NO2−functionalized poly(aryloxyphosphazenes) was characterized using Scanning electron microscopy. The COOH−functionalized poly(aryloxyphosphazenes) can act as pH sensing electrodes. Furthermore, the present research demonstrates that the electrochemical synthesis of NH2−functionalized poly(aryloxyphosphazenes) is a suitable methodology for the reduction of nitro substituents avoiding the generation of hazardous wastes. The reduction of NO2−functionalized poly(aryloxyphosphazenes) degree is reported.

Electrochemical Studies of Poly(ethylene oxide)–Sodium Perchlorate Composite for Battery Application

Electrochemical Studies of Poly(ethylene oxide)–Sodium Perchlorate Composite for Battery Application

Electrical and electrochemical studies of poly(vinylidene fluoride)–clay nanocomposite gel polymer electrolytes for Li-ion batteries

A study is conducted on the electrical and electrochemical properties of nanocomposite polymer electrolytes based on intercalation of poly(vinylidene fluoride) (PVdF) polymer into the galleries of organically modified montmorillonite (MMT) clay. A solution intercalation technique is employed for nanocomposite formation with varying clay loading from 0 to 4 wt.%. X-ray diffraction results show the β phase formation of PVdF on intercalation. Transmission electron microscopy reveals the formation of partially exfoliated nanocomposites. The nanocomposites are soaked with 1 M LiClO 4 in a 1:1 (v/v) solution of propylene carbonate (PC) and diethyl carbonate (DEC) to obtain the required gel electrolytes. The structural conformation of the nanocomposite electrolytes is examined by Fourier transform infrared spectroscopy analysis. Examination with a.c. impedance spectroscopy reveals that the ionic conductivity of the nanocomposite gel polymer electrolytes increases with increase in clay loading and attains a maximum value of 2.3 × 10 −3 S cm −1 for a 4 wt.% clay loading at room temperature. The same composition exhibits enhancement in the electrochemical and interfacial properties as compared with that of a clay-free electrolyte system.

Electrochemical studies of poly (3,4-ethylenedioxythiophene) PEDOT/VS 2 nanocomposite as a cathode material for rechargeable lithium batteries

Here, we demonstrate the electrochemical characterization of a new type of layered poly (3,4-ethylenedioxythiophene) PEDOT/ VS 2 nanocomposite. It has been prepared via flocculation of delaminated VS 2 with subsequent in situ oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) with VS 2 as a host material in the presence of an external oxidizing agent. The interlayer spacing of VS 2 expands from 5.71 to 14.01 Å and this interlayer separation is consistent with the existence of a monolayer of PEDOT in the VS 2 framework. X-ray diffraction, XPS and TEM studies have been shown the change in interlayer separation is consistent with the existence of two phases of organic and inorganic species in the nanocomposites corresponding to the intercalation of PEDOT in the VS 2 framework. The application potential of the nanocomposite as a cathode material for rechargeable lithium batteries is also demonstrated by the electrochemical intercalation of lithium into the PEDOT/VS 2 nanocomposite, where a significant enhancement in the discharge capacity is observed (∼130 mAh/g) compared to that (80 mAh/g) for pristine VS 2.

Electrochemical studies of poly(vinylferrocene) films in aqueous and non‐aqueous electrolyte solutions

Electrochemical studies of poly(vinylferrocene) films in aqueous and non‐aqueous electrolyte solutions

Electrochemical studies of poly(vinylferrocene) films in aqueous and non-aqueous electrolyte solutions

The electrochemical response of a conducting polymer, poly(vinylferrocene) (PVF), as a function of the electrolyte media, is reported. Cyclic voltammetry has been used to investigate the redox behaviour of the films spin-cast onto glass electrodes (ITO). The films were cycled in non-aqueous (propylene carbonate and tetramethylene sulfone) electrolyte solutions containing different salts: sodium, lithium and tetrabutylammonium perchlorates (NaClO4, LiClO4 and TBAClO4), tetrabutylammonium hexafluorophosphate and tetrafluoroborate (TBAPF6, TBABF4). Aqueous electrolyte solutions of NaClO4 and LiClO4 have also been studied for comparison with the reported literature data. Some of the criteria for reversible systems have been tested for the different electrolytes used. Cyclic voltammetry experiments have also been carried out on the same films, after 3 months, using electrolyte solutions in propylene carbonate and tetramethylene sulfone. The results show that the film has a ‘solvent sensitivity’ effect, and the charge density changes according to the solvent used. There is a reversible charge sensivity effect when the films are cycled between propylene carbonate- and tetramethylene sulfone-based electrolytes. © 2000 Society of Chemical Industry

Chemical Synthesis, Characterization, and Electrochemical Studies of Poly(3,4-ethylenedioxythiophene)/Poly(styrene-4-sulfonate) Composites

Poly(3,4-ethylenedioxythiophene)/poly(styrene-4-sulfonate) (PEDOT/PSS) composites have been prepared from aqueous and aqueous acetonitrile solutions of EDOT and NaPSS by oxidation using Fe(III) salts. Powders with PEDOT to PSS ratios ranging from 0.3 to 4.2 and electronic conductivities as high as 10 S cm-1 have been obtained in good yields. The PEDOT/PSS blends are cation exchangers and exhibit facile eletrochemistry in both aqueous and acetonitrile media. Impedance measurements have shown that 30 μm thick PEDOT/PSS layers have proton conductivities as high as 0.03 S cm-1.

An electrochemical study of poly(paraphenylene) in conductive polymer bilayer electrodes

Abstract Polymerization and redox responses of bilayers consisting of poly(paraphenylene) (PPP)|poly(3-octylthiophene) (POT) (signifying inner layer|outer layer), POT|PPP, PPP|polypyrrole (PPy) and PPy|PPP have been studied. The bilayers were made electrochemi Pt substrate. The bilayers obtained with PPP and POT were found to be compact and thinner than the charges used for polymerization of both layers separately would predict. In the bilayer electrodes with PPP as the inner layer and POT as the outer layer, the charge involved in the redox process (doping-undoping) was in some combinations up to two times higher than that of the same layers separately. In the bilayer combination PPP|PPy, the outer PPy layer could be charged although the PPP layer was still in its neutral state. Preparation of PPy|PPP bilayers was complicated by the high oxidation potential of biphenyl, resulting in simultaneous overoxidation of the inner PPy layer.

Electrochemical study of poly(vinyl chloride)/polypyrrole blends

Blends were obtained by impregnation of an insulating polymer matrix, poly(vinyl chloride), with an oxidant, FeCl 3, followed by exposure to pyrrole vapor. The redox properties of films of the blends obtained by this method were studied by cyclic voltammetry and impedance spectroscopy. The results show that thin films (20 μm) are more electroactive than thick films (100 μm) although the proportion of polypyrrole is the same for both ( ca. 38%). This electroactive behavior is in agreement with morphology observations, which show different phase separation mechanisms as a function of the film thickness: a spinodal mechanism for the thin film and a binodal mechanism for the thick film.

Electrochemical study of poly(3-octylthiophene) film electrodes. Impedance of the polymer film semiconductor-electrolyte interface

The small amplitude ac data of the poly(3-octylthiophene) electrode—electrolyte system are analysed. The measurements are done at several dc potentials for different thicknesses of the polymer film and for different electrolyte concentrations (lithium tetrafluoroborate in propylene carbonate). The Ladder type electrical circuit model is found to give best fit of the data. The high frequency double layer capatance is shown to contain contributions from both sides of of the interface, ie the space charge layer of the polymer semiconductor and the Helmholtz layer of the electrolyte. The experimental data are compared with calculated data by using a simple model of two capacitors in series, for a potential range including that where the reversible oxidation of the polymer takes place. The adsorption/surface state capacitance is shown to pass through a maximum and the corresponding coverage of surface species is determined. The structure of the double layer, the physical interpretation of the model parameters, and the energy level diagram for the polymer semiconductor electrode are proposed.

Electrochemical Studies of Poly(mercaptohydroquinone) and Poly(mercapto-p-benzoquinone) Films Prepared by Electrochemical Polymerization. VI.Electroreduction of l-Cystine on Thiolates Fixed in the Polymer Film

Abstract Electrocatalytic reduction of l-cystine (CySSCy) was examined on glassy carbon electrodes coated with the title conductive polymer in which Pt, Pd, Cu, Ag, and Hg thiolates were fixed. Pt and/or Pd thiolate fixed in the polymer behaved as excellent electrocatalytic active sites for reductive cleavage of the sulfur–sulfur bond in CySSCy.

Electrochemical study of poly(3-octylthiophene) film electrodes I. Electrolyte effects on the voltammetric characteristics of the polymer. Three states of the polymer film

Poly(3-octylthiophene) (POT) is an electrically conductive polymer in its oxidized forms. The oxidation-reduction (doping-undoping) process of the electrochemically synthesized polymer was studied by cyclic voltammetry. Different oxidation (doping) levels of POT result in different properties of the polymer electrode. The relative changes in conductivity when going from neutral to reversibly oxidized and finally to irreversibly oxidized POT were followed by resistance measurements. The electrolyte effects were analysed and new factors due to electropolymerization and doping processes determining the electrode properties were found. The electrochemically synthesized POT was found to be insoluble in chloroform.

Electrochemical study of poly(3-octylthiophene) film electrodes II. Reversible redox/conductivity state switching. Impedance study

Poly(3-octylthiophene) (POT) is a polymer which can be made electrically conductive by oxidation (p-doping). The presence of the octyl side chains makes this polymer melt-processable and soluble in common organic solvents. Films of POT were deposited on a Pt disc by electrochemical polymerization of the monomer and by solution-casting of chemically synthesized POT. The electrochemical properties of the Pt/POT electrodes were then studied in lithium tetrafluoroborate-propylene carbonate solution for various thicknesses of the polymer film. Impedance/admittance measurements using the Fourier transform faradaic admittance measurements technique were performed at d.c. potentials corresponding to neutral POT and to different reversible oxidation levels of POT, and the impedance data were fitted to an equivalent electrical circuit. It was thus possible to follow how the parameters related to charge transfer, diffusion and double layer changed with the oxidation level of POT.

Magnetic resonance and electrochemical studies of poly (phenylene vinylene)

The structure of poly( p-phenylene vinylene) (PPV) is investigated by 13C solid-state n.m.r. Electrochemical oxidative doping of PPV is studied by cyclic voltammetry and in situ e.s.r. experiments: both methods give evidence for a reversible oxidation process at 1.23 V superimposed on an irreversible one. The electrochemical response of the ‘reversible’ spin is consistent with polaron formation upon doping.

Electrochemistry of Thermally Cyclized Polyimide Films

An electrochemical study of poly(4,4′oxydiphenylenepyromellitimide), better known as Kapton®, was conducted. The cyclic voltammetric response of the thermally cyclized polymer in aqueous electrolytes shows two chemically reversible electron transfers. Electrochemical methods indicate the rate of charge propagation in this polymer is principally dependent upon mass transfer. Surprisingly, the investigation of this polymer in nonaqueous electrolytes showed exceedingly poor electrochemical behavior relative to the aqueous electrolytes. The difference between the electrochemistry of the polymer in aqueous vs. nonaqueous electrolytes is believed to be due to solvent effects on the electron transfer properties rather than mass‐transfer effects.

Electrochemical study of poly(3-methylselenophene)

We describe the electrochemical behaviour of poly(3-methylselenophene) in acetonitrile. The level of doping δ is determined by chronocoulometric measurement. Cyclic voltammetry, chronoamperometry and chronocoulometry are used to study the response time and the stability of the polymer. Our results show that poly(3-methylselenophene) is very promising for possible applications.

Electrochemical study of poly(phas) in acetonitrile and water + acetonitrile electrolytes

The behaviour of electrodes coated with either monomeric or polymeric anthraquinone (AQ) deposits has been investigated in aqueous media. The basal compound PHAS ([1-(pyrrol-1-yl)-hex-6-yl]-9,10-anthraquinone-2-sulphonate), consisting of an anthraquinone linked to a pyrrole moiety via an alkyl linkage, is electroactive either as air-dried monomer layers or when it is electropolymerized on different electrodes at various pHs. However, platinum-coated electrodes were found to work only at basic pH (7–14), whereas glassy carbon electrodes work in the entire pH range (0–14), with the redox potential of the AQ/AQH 2 couple depending linearly on ambient pH. Unlike the monomer layers, polymer films are electroactive only if 30% acetonitrile is added to the aqueous electrolyte.

Electrochemical Studies of Poly(mercaptohydroquinone) and Poly(mercapto-p-benzoquinone) Films Prepared by Electropolymerization. I. Preparation of pH Microsensor and Its Fundamental Characteristics

Abstract Carbon fibers were electrochemically modified with poly(mercaptohydroquinones). These modified carbon fiber electrodes showed excellent Nernstian response to pH from ca. 2 to 10 and could respond within 2s in the pH range from 3 to 8. These electrodes could work well one month after kept stored in a weak acidic buffer solution and could be easily restored by electroreduction even after their functions had been lowered by successive pH measurements.