Electropolymerization of poly(3-methylthiophene) in pyrrolidinium-based ionic liquids for hybrid supercapacitors

The ionic liquids (ILs) N-butyl-N-methyl-pyrrolidinium trifluoromethanesulfonate (PYR₁₄Tf) and N-methyl-N-propyl-pyrrolidinium bis(fluorosulfonyl)imide (PYR₁₃FSI) are investigated as electropolymerization media for poly(3-methylthiophene) (pMeT) in view of their use in carbon/IL/pMeT hybrid supercapacitors. Data on the viscosity, solvent polarity, conductivity and electrochemical stability of PYR₁₄Tf and PYR₁₃FSI as well as the effect of their properties on the electropolymerization and electrochemical performance of pMeT, which features >200 Fg⁻¹ at 60 °C when prepared and tested in such ILs, are reported and discussed; the results of the electrochemical characterization in N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide of the so-obtained pMeT are also given, for comparison.     

Morphological and electrochemical characterization of a poly(3-methylthiophene)/PVDF composite

Composite electrodes were prepared via electrochemical polymerization of 3-methylthiophene in porous PVDF membranes of various thicknesses. The electrochemical properties were determined by cyclic voltammetry and charge-discharge tests and the possible correlation of the results with the morphology of the host membranes was examined. The best definition of n- and p-doping/undoping processes and the biggest capacitance (82 F g⁻¹) were obtained with a 27.5 μm-thick composite. Further characterization of this composite using electrochemical impedance spectroscopy revealed three behaviors associated with variation in the oxidation state of poly(3-methylthiophene) during transition from the n-undoping to p-doping states. The behavior of the charge transfer resistance and the double layer capacitance as a function of the applied potential were also determined.     

Photoluminescence properties of new poly(N-vinylcarbazole)-3-methylthiophene (PVK-3MeT) graft copolymer

Steady-state and time-resolved photoluminescence (TRPL) measurements are used in order to investigate the emission properties of new graft copolymer involving poly(N-vinylcarbazole) (PVK) and poly(3-methylthiophene) (PMeT) named PVK-3MeT. The photo-generated species in PVK-3MeT are identified as singlet intrachain excitons. Furthermore, radiative and nonradiative lifetimes have been calculated. The observed changes in the photo-physical properties of the different condensed phases could be directly related to the nanostructure of the material. The use of PVK in the chemical synthesis allows the obtaining of a new organic material with better emission and slowly radiative recombination compared to those of polythiophenes indicating that the radiative channel is more enhanced. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Integrated urea sensor module based on poly(3-methylthiophene)-modified p-type porous silicon substrate

Integrated three-electrode system module composed of a porous silicon (PS)-based sensing electrode, an Ag/AgCl thin film reference electrode (RE_tf), and a Pt thin film counter electrode (CE) was fabricated for monitoring urea level of artificially-prepared body fluid. After thermal evaporation of the 200 nm thick Ag on the Ti-underlayered planar p-type silicon (p-Si) substrate, the Ag Film was oxidized in a FeCl₃ solution to obtain the Ag/AgCl RE_tf. Multi-layered RE_tf was clearly shown from results of the auger electron spectroscopy (AES) depth profile. The nernstian slope of the RE_tf also showed good reproducibility. The PS layer was formed by electrochemical anodization with applying constant current to the p-Si substrate in an ethanolic HF solution and the macro PS (2 μm diameter and 10 μm depth) was obtained. The electrochemical active area (A_ea) of the PS-based Pt thin film electrode was determined from the cyclovoltammetric result of redox reactions of K₃Fe(CN)₆ on the electrode surface and compared with the A_ea of the planar silicon (PLS)-based Pt film substrate. After electropolymerization of the conductive poly(3-methylthiophene) (P3MT) on the PS-based Pt thin film, urease (isoelectric point ≈ 4.1) molecules were electrostatically doped into the P3MT film by applying positive bias. Amperometric calibration curves for both PS- and PLS-based sensing electrodes were compared in the range of 0.1–125 mM urea concentrations and the cross-sectional scanning electron microscopy (SEM) image of the PS-based sensing electrode was also shown.     

Building action of various types of inorganic electrolytes

The builder effects of a series of condensed phosphates and other types of electrolytes on the detergency for standard soiled cloth have been measured. The detergency highly depends on the type of electrolytes and, in general, increases with increasing pH of detergent solutions. The building action of phosphates is greater than that of other electrolytes when it is compared at the same pH. The alkalinity, including alkali buffering capacity, of various electrolytes and the sequesteration capacity of phosphates for calcium ion have also been determined. From the results, the building action of inorganic electrolytes in a detersive system has been discussed in connection with the suspension stability of colloidal particles reported in previous papers. The following factors are at least important in the building action of inorganic compounds: (a) the suspension of soil particles in a detergent solution, (b) the sequesteration of heavy metal ions, and (c) the alkalinity including buffering action to keep the solution alkaline. Condensed phosphates, in particular sodium tripolyphophate, have an ability to satisfy these three factors although their alkalinity is not so strong.     

Discharge behaviour of copper(II) halide cathodes with molten nitrate electrolytes

This paper describes the discharge behaviour between 150 and 220°C of cells using copper(II) halide as the cathode material and molten nitrate as the electrolyte for a reserve battery of high energy density running at medium temperatures. At these temperatures a lithium–aluminium alloy/copper(II) chloride cell can be discharged at a current density of 50mAcm–2. The open-circuit potentials are 3.45V (against 20wt% lithium–aluminium alloy). Discharge results on the combination LiAl/LiNO3–KNO3/CuCl2 cells show a capacity of 1343Cg–1 to zero voltage at a current density of 50mAcm–2 at 230°C. In practice, this is equivalent to a specific energy output of 356Whkg–1 of cathode to a 70% voltage cut-off. The compatibility of copper(II) chloride with nitrate electrolytes has been investigated. Copper(II) chloride appears to be compatible with nitrate up to about 260°C. The performance of the LiAl/NO3/CuF2 cell was very poor giving a capacity of 50Cg–1.     

A red-to-gray poly(3-methylthiophene) electrochromic device using a zinc hexacyanoferrate/PEDOT:PSS composite counter electrode

In this paper, we describe a novel red-to-gray poly(3-methylthiophene) (PMeT) electrochromic device (ECD) with the aid of a zinc hexacyanoferrate (ZnHCF)/PEDOT:PSS counter electrode. The application of ZnHCF to an ECD is first reported. ZnHCF has long suffered from poor deposition yield problem, but we demonstrate that a robust ZnHCF film can be prepared by spin coating of a liquid suspension composed of ZnHCF nanoparticles and PEDOT:PSS ink on ITO. It was found that the ZnHCF/PEDOT:PSS composite worked much better with PMeT than pure ZnHCF or pure PEDOT:PSS from both electrochemical and optical aspects. With a LiClO₄/PC electrolyte, the PMeT ECD having ZnHCF/PEDOT:PSS as its counter electrode could be reversibly switched between its red state (>0.8 V) and its gray state (<0 V). For a 2 cm × 2 cm prototype device, the response time for coloration was less than 1 s. The maximum transmittance modulation of the device could attain 45.3% at 750 nm, which resulted in a corresponding coloration efficiency of 336.8 cm²/C. The maximum contrast ratio was 5.45 at 720 nm. In addition, the charge capacity of the ECD could retain 95% of its original value after 10,000 cycles of cyclic voltammetry aging test, although an electrodeposited PMeT film alone could be cycled several hundred times only. To sum up, this work proposes a new, cost-effective transparent counter electrode and brings a stable, high visual-contrast PMeT ECD prototype for further development of a red-color bistable display.     

无机高分子混凝剂聚合氯化铁的合成方法

作者着重介绍了氮氧化物为催化剂,以填料塔为反应器,以钢铁酸洗废液或铁悄为含铁原料合成聚合氧化铁工艺。同时对于该气液反应的机理,影响因素,解决措施进行了讨论。     

P(4-VP-co-AN)共聚物凝胶电解质的性能研究

采用自由基溶液聚合法合成出P(4-VP-co-AN),通过与交联剂发生化学交联反应固化液体电解质,制得凝胶电解质,并将其应用于染料敏化太阳能电池。当AN为聚合物质量分数为25%时,制备的凝胶电解质DSSCs具有较好的光电性能;同时,交联剂含量为P(4-VP-co-AN)质量的1.5%时,制备的凝胶电解质DSSCs光电性能最佳,与纯液体电解质DSSCs相比,其光电转换效率和最大输出功率分别达到液体电解质电池的77.38%和78.57%。     

Conductivity hysteresis in polymer electrolytes incorporating poly(tetrahydrofuran)

Conductivity hysteresis and room temperature ionic conductivities >10⁻³ S/cm were recently reported for electrolytes prepared from blends of an amphiphilic comb copolymer, poly[2,5,8,11,14-pentaoxapentadecamethylene (5-hexadecyloxy-1,3-phenylene)] (polymer I), and a linear multiblock copolymer, poly(oligotetrahydrofuran-co-dodecamethylene) (polymer II), following thermal treatment [F. Chia, Y. Zheng, J. Liu, N. Reeves, G. Ungar, P.V. Wright, Electrochim. Acta 43 (2003) 1939]. To investigate the origin of these effects, polymers I and II were synthesized in this work, and the conductivity and thermal properties of the individual polymers were investigated. AC impedance measurements were conducted on I and II doped with LiBF₄ or LiClO₄ during gradual heating to 110 °C and slow cooling to room temperature. Significant conductivity hysteresis was seen for polymer II, and was similarly observed for poly(tetrahydrofuran) (PTHF) homopolymer at equivalent doping levels. From thermogravimetic analysis (TGA), gel permeation chromatography (GPC) and ¹H NMR spectroscopy, both polymer II and PTHF were found to partially decompose to THF during heat treatment, resulting in a self-plasticizing effect on conductivity.     

Effect of inorganic electrolytes on dissolution behavior of mixed anionic-amphoteric surfactant systems

The effects of some inorganic electrolytes on the dissolution behavior of anionic-amphoteric mixed surfactant systems have been studied in terms of dissolution temperature of a hydrated solid surfactant; these systems are sodium dodecyl sulfate (SDS) - N^α,N^α-dimethyl-N^ɛ-lauroyl lysine (DMLL), including different inorganic electrolytes (NaCl, NaSCN, or CaCl₂). The dissolution temperatures of mixed surfactant systems are lower than those of pure surfactant solutions and become less than 0 C at a certain mole fraction of surfactants. As the concentration of NaCl increases, the dissolution temperatures of systems at a DMLL mole fraction lower than 0.4 increase, while those of systems at a ratio higher than 0.9 remain almost the same. With increasing concentration of NaSCN, the dissolution temperatures of systems at a DMLL mole fraction lower than 0.4 increase, while those of systems at a ratio higher than 0.9 decrease. For CaCl₂ systems, there exists a maximum in the dissolution temperature at a certain composition, because addition compound formation between anionic and zwitterionic surfactants occurs due to the presence of calcium ions.     

Enhancing electrochemical performance of sodium Prussian blue cathodes for sodium-ion batteries via optimizing alkyl carbonate electrolytes

Sodium Prussian blue (SPB) with a cubic structure was successfully synthesized by a simple precipitation method in a hot acidic medium. Scanning electron microscopy images showed that the as-prepared SPB consisted of many microcubic structures with different morphologies and sizes because of the tailoring of its surface morphology by etching. The Fourier-transform infrared spectroscopy and energy-dispersive X-ray spectroscopy results indicated the existence of interstitial water and the replacement of Na⁺ ions by H⁺ ions in the SPB material. In addition, when used as a sodium-ion battery (SIB) cathode, the as-prepared SPB showed significantly different electrochemical behaviors in two different alkyl carbonate electrolytes (ethylene carbonate and propylene carbonate with 2% fluoroethylene carbonate electrolyte (EC-PC-2% FEC) and PC-2% FEC electrolyte). The results showed that in the PC-2% FEC electrolyte, the as-prepared SPB showed excellent rate capability and cycle stability, and hence was found to be a promising SIB cathode material.     

Radiotracer self-diffusion measurements in poly(ethylene oxide) and poly(propylene oxide) electrolytes

Radiotracer measurements of the ²²Na⁺ and S¹⁴CN^? diffusion coefficients in PEO-NaSCN (x = 6, 8 and 12) and PPO-NaSCN (x = 8) are reported, where PEO = poly(ethylene oxide), PPO = poly(propylene oxide), and x = [EO units]/[NaSCN] or [PO units]/[NaSCN]. The results are compared with ionic conductivity measurements on the same samples. Measurements for the PEO samples were taken above the melting point of pure PEO and the results interpreted, particularly for the sample most dilute in salt, in terms of ‘free ions’ as the dominant charge carriers. For PPO the results are less clear, although there is good evidence for the onset of ion aggregation prior to separation of salt at higher temperatures.     

Localized nature of the luminescence during galvanostatic anodizing of high purity aluminium in inorganic electrolytes

Luminescence during galvanostatic anodizing of high purity aluminium containing Fe, Si and Cu as major impurities in inorganic electrolytes, typically an aqueous solution of ammonium borate, was found to be a local phenomenon which takes place at “flaws” in the growing oxide film. The intensity of the luminescence was found to be closely correlated to the concentration of “flaws” in the film: the intensity of the luminescence being roughly proportional to the concentration of “flaws” in the film. Rough estimate of the concentration of ”flaws“ in the film formed on “as received”, “chemically cleaned” and “electropolished” aluminium plate was 2 × 10⁸.3 × 10⁷ and 10⁵/cm², respectively. Any mechanism deeming the luminescence to be an electroluminescence in a homogeneous oxide with the collision excitation of the impurities or with the recombination at impurity centres has been rejected.     

Charge—discharge characteristics and structural change in various niobium sulfide cathodes for lithium-nonaqueous secondary batteries

Electrochemical behaviors of niobium sulfides such as 3R-Nb_1+xS₂ (x = 0.00 ≈ 0.25), 2H-NbS₂ and NbS₃ for lithium batteries are investigated in 1 M LiClO₄-propylene carbonate solution. The cathodic reaction in the charge-discharge cycle of the disulfides is shown as follows:

X-ray diffraction measurement and open circuit potential data show that 3R-Nb_1.00S₂ gives continuous structural change along c-axis reversibly with cycling, where x takes from 0 to 1, whereas 2H-NbS₂ gives the stepwise change also reversibly with cycling, where x is at least 1. On the other hand, NbS₃ yields the ternary phase of Li_xNbS₃ giving an amorphous X-ray pattern and shows irreversible structural change with cycling. When the charge-discharge cyclings are carried out at a constant capacity of 0.50 equivalent mole^?1 of sulfide and a current density of 0.20 mA cm^?2, 3R-Nb_1.00S₂ can be cycled over 100 times without an increase in the charge potential, whereas in 2H-NbS₂ and NbS₃ the charge potentials rise to 4.6 V vs Li/Li⁺ with cycling, which limits the cycle number to 30 ≈ 50 times. This would be due to the fact that 3R-Nb_1.00S₂ shows the reversible structural change with keeping the original crystal lattice with cycling.     

Stable composite electrolytes of PVDF modified by inorganic particles for solid-state lithium batteries

Polymer electrolytes have been attracting much attention because of their flexibility and easy follow-up processing, but their Li⁺ conductivity in lithium-metal batteries (LIBs) is unsatisfactory. Stable composite electrolytes of poly (vinylidene fluoride) (PVDF) polymer with high lithium-ion conductivity have been prepared by a trigger structural modification of Li_6.5La₃Zr_1.5Nb_0.25Ta_0.25O₁₂ (LLZNTO) garnet ceramic and TiO₂ oxide. The influences of various amounts of TiO₂ and LLZNTO on electrochemical performance were systematically examined. These composite electrolytes exhibited maximal Li⁺ conductivity of 2.89 × 10⁻⁴ S cm⁻¹, which is consistent with the value of pure ceramic electrolytes. Furthermore, it possessed the stable long-term Li cycling and the wide electrochemical window, involving repeated Li plating/stripping at 0.2 mA cm⁻² over 280 h without failure. The discharge specific capacity and Coulomb efficiency for all-solid-state LIBs assembled with these membranes delivered outstanding cycling stability with high discharge capacities (117.9 mA h g⁻¹) at 0.1 C rate and Coulomb efficiency reached 99.9% after 25 cycles. The high Li⁺ conduction capability can be ascribed function of introducing TiO₂ and LLZNTO to restrain tremendously the crystalline behavior of the polymer. Furthermore, the LLZNTO can be complex with PVDF for dehydrofluorination, and it can also offer a burst transportation route for lithium ions. This system might serve as an attractive use for polymer solid electrolytes and open up new possibilities for safe all-solid-state LIBs.     

Bismuth oxide-coated (La,Sr)MnO3 cathodes for intermediate temperature solid oxide fuel cells with yttria-stabilized zirconia electrolytes

Taking Y₂O₃ stabilized Bi₂O₃ (YSB) as an example, bismuth oxide-added (La,Sr)MnO₃ (LSM) is evaluated as a cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs) with 8 mol% Y₂O₃ stabilized ZrO₂ (YSZ) electrolytes. YSB was added to LSM cathodes using an impregnation method, dramatically improving the electrode performance. The interfacial polarization resistance R_p, at 700 °C for the electrode coated with 50 wt.% of YSB is 0.14 Ω cm², which is only 0.2% of the value for a pure LSM electrode. The high oxygen ionic conductivity and the catalytic activity of YSB, as well as the favorable electrode microstructure are likely reasons for the dramatic reduction of R_p. The YSB-added LSM cathodes also exhibited lower overpotential and higher exchange current density than the pure LSM cathode. Moreover, these electrodes show much lower R_p than that of parallel-fabricated LSM electrodes with samaria-doped-CeO₂ as well as other LSM-based electrodes reported in the literature, demonstrating the superiority of the of YSB as the ionic conduction component in composite LSM electrodes. The superior performance of the single cell further demonstrates that the bismuth oxide-added LSM cathode is an excellent candidate for IT-SOFCs.     

Optimization of electrically conductive films: Poly(3-methylthiophene) or polypyrrole in Kapton

A method to generate conductive films composed of small amounts of conductive polymer absorbed into the surface of polyimide films has been optimized. Both pyrrole (PY) and 3-methylthiophene (3MT) were evaluated as precursors for the conductive phase. Predictive models were empirically derived for each precursor to describe the effects of polymerization variables on the conductivity of the films. The variables studied were found to be highly synergistic. An optimum set of conditions was found for each conductive polymer that produces the highest conductivity. Using p-3MT as the conductive phase, films with conductivity as high as 5.7 Ω⁻¹ cm⁻¹ can be produced, an improvement of four orders of magnitude over previously reported results with Kapton as a base polymer. The highest conductivity achieved using p-PY as the conductive phase was 0.041 Ω⁻¹ cm⁻¹, still a two order of magnitude improvement over previously reported results. Mean mechanical properties of the 3MT-treated films were not significantly lower than that for untreated Kapton. The conductivities of p-3MT/Kapton films tested over time under ambient temperature in air persist fairly well for 300 days. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 821–834, 1997     

Construction of hybrid nanocomposites containing Pt nanoparticles and poly(3-methylthiophene) nanorods at a glassy carbon electrode: Characterization, electrochemistry, and electrocatalysis

Hybrid nanocomposites containing Pt nanoparticles (nano-Pt) and poly(3-methylthiophene) (P3MT) nanorods at glassy carbon surfaces have been successfully prepared by use of an in situ cyclic voltammetry (CV) method. Field emission scanning electron microscope (FE-SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltagrams were used to characterize the properties of these nanocomposites. SEM images showed that nano-Pt were located on the surface of P3MT nanorods and that they formed a three-dimensional (3D) porous nanostructure. EIS and CV results demonstrated that these hybrid nanocomposites had good conductivities, and could accelerate the electron-transfer rates of redox ions. From the results of electrochemical oxidation of methanol and nitrite, we observed that this nanocomposite-modified electrode exhibited excellent electrocatalytic activity, which might be useful in biosensors and/or fuel cells.