Presence Of Propylene Carbonate Research Articles

Co-Solvent Electrolyte Engineering for Stable Anode-Free Zinc Metal Batteries.

Anode-free metal batteries can in principle offer higher energy density, but this requires them to have extraordinary Coulombic efficiency (>99.7%). Although Zn-based metal batteries are promising for stationary storage, the parasitic side reactions make anode-free batteries difficult to achieve in practice. In this work, a salting-in-effect-induced hybrid electrolyte is proposed as an effective strategy that enables both a highly reversible Zn anode and good stability and compatibility toward various cathodes. The as-prepared electrolyte can also work well under a wide temperature range (i.e., from -20 to 50 °C). It is demonstrated that in the presence of propylene carbonate, triflate anions are involved in the Zn2+ solvation sheath structure, even at a low salt concentration (2.14 M). The unique solvation structure results in the reduction of anions, thus forming a hydrophobic solid electrolyte interphase. The waterproof interphase along with the decreased water activity in the hybrid electrolyte effectively prevents side reactions, thus ensuring a stable Zn anode with an unprecedented Coulombic efficiency (99.93% over 500 cycles at 1 mA cm-2). More importantly, we design an anode-free Zn metal battery that exhibits excellent cycling stability (80% capacity retention after 275 cycles at 0.5 mA cm-2). This work provides a universal strategy to design co-solvent electrolytes for anode-free Zn metal batteries.

Operando Synchrotron X-ray Diffraction Studies on TiS2: The Effect of Propylene Carbonate on Reduction Mechanism

We present herein a systematic study of solvent co-intercalation during electrochemical reduction of titanium disulfide in lithium cells using state of the art in situ cells and synchrotron X-ray diffraction. To understand the role of the electrolyte components, four salts (LiBF4, LiBOB, LiPF6 and LiTFSI) and three solvents (ethylene carbonate, propylene carbonate and dimethyl carbonate) were investigated. Various types of in situ cells were assembled and X-ray diffraction patterns were collected in operando upon cycling. Co-intercalated phase formation was found to be triggered by the presence of propylene carbonate and to be electrochemically driven. This co-intercalated phase is formed in the early stages of reduction, with cell parameters a = 3.514 Å, c = 17.931 Å, corresponding approximately to a tripling of the pristine TiS2 cell along the c-axis. This phase does not seem to evolve upon further oxidation and hence induces an overall loss of capacity. Whereas the nature of the anion does not appear to influence the co-intercalated phase formation, the content of propylene carbonate in the electrolyte is clearly correlated to both its amount and the extent of capacity loss.

Implementation of Sustainable Solvents in Green Polymerization Approaches

AbstractIn modern polymer chemistry directed toward the synthesis of conjugated materials, the synthetic routes devised to achieve the process sustainability are based on CH bond activation. This prerequisite distinguishes both the tandem Suzuki−Heck as well as the direct arylation polymerizations (DArP); however, their compatibility with environmentally benign solvents still represents a challenge. In this paper, the implementation of sustainable solvents for the synthesis of poly(9,9‐dioctylfluorenylene‐vinylene) by using the traditional Pd(AcO)2/P(o‐Tol)3/NEt3 catalytic system is described. It is assessed that selected green solvents (i.e., anisole and propylene carbonate) constitute the ideal media for the tandem Suzuki–Heck polymerization. Furthermore, by modulating medium polarity using mixtures of these green solvents and changing the reaction temperature, a suitable compromise between high molecular weights and regioregularity of the resulting polymers is reached. Conversely, the presence of propylene carbonate is deleterious for the DArP of 2‐bromo‐3‐hexylthiophene, while it is found that catalyst performances in anisole strictly depend on the palladium source used. The best conditions are obtained using PdCl2(PPh3)2 as the precatalyst, affording a highly regioregular (93%) poly(3‐hexylthiophene) in quantitative yields and high molecular weights (26.7 kg mol−1).

Formation of a hydrophobic polyiodide complex during cathodic oxidation of iodide in the presence of propylene carbonate in aqueous solutions, and its application to a zinc/iodine redox flow battery

A polyiodide complex has been newly obtained during the cathodic oxidation of iodide ions (I−) in the presence of propylene carbonate (PC). This complex demonstrates features of both ionicity and hydrophobicity. The properties and structure of this complex were investigated and discussed in the light of electrochemical investigations, instrumental analyses, and theoretical calculations using quantum chemistry. The oxygen atom of the CO bond in PC was considered to play an essential role in forming this complex, and a large dipole moment structure between I2 and PC was suggested by the theoretical calculations. This PC/I2 structure was considered to play an essential role in enhancing the dissolution rate of I2 films on a cathode and in accelerating the cathodic oxidation of I−. A model for the structure of this complex is demonstrated. A zinc/iodine redox flow battery of an aqueous-based single electrolyte-type was examined as an application of this complex to a battery without a cation-exchange membrane. Over 90% Coulombic efficiency was observed through charge and discharge cycles.

Single lithium-ion polymer electrolytes based on poly(ionic liquid)s for lithium-ion batteries.

A promising method of synthesizing a lithium-containing room temperature polymeric ionic liquid (PIL) by utilizing the zwitterionic effect to turn a lithium salt into a liquid for single lithium-ion conduction was proposed. In this work, the room temperature PIL was constructed by the equimolar monomer mixture of zwitterion 3-(1-vinyl-3-imidazolic)propanesulfonate (VIPS) and 4-styrenesulfnny(trifluoromethylsulfony)imde (LiSTFSI) based on intermolecular electrostatic interactions. In situ photopolymerization with flexible chain poly(ethylene glycol)methyl ether methacrylate (PEGM) and cross-linker poly(ethylene glycol)dimethacrylate (PEGDM) in the presence of propylene carbonate (PC) generated free-standing PIL electrolyte films. The PIL electrolytes with Li+-rich channels have an excellent lithium transference number approaching unity (0.93 at room temperature) while attaining comparable ionic conductivity (σ ≈ 1.31 × 10-4 S cm-1 at 30 °C). The charge-discharge performance of a Li/LiFePO4 half-cell equipped with this PIL electrolyte would provide a promising model system for novel single lithium ion conductors.

On the interaction of carbon electrodes and non conventional electrolytes in high-voltage electrochemical capacitors

This study is essentially based on innovative electrolytes such as the organic salt N-methyl-N-butylpyrrolidinium tetrafluoroborate (Pyr14BF4) dissolved in propylene carbonate (PC) and the pure ionic liquid (N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI) and its solution in PC. Activated carbon cloths were used as self-standing binder-free electrodes. It is found that the presence of impurities in carbon electrodes may lead to electrolyte decomposition and electrode degradation which notably affect the electrochemical double-layer capacitor (EDLC) performance. Such processes greatly depend on the composition of both the electrode and the electrolyte, being much less significant with solvent-containing electrolytes. By raising the operation temperature to 60 °C, the EDLC performance in the ionic liquid Pyr14TFSI is notably improved due to a relevant decrease in the viscosity and increase in ionic conductivity. By contrast, the presence of impurities, e.g., Zn and Al, in the electrodes remarkably reduces the electrolyte stability and a thick layer of decomposition products completely covers the carbon fibers after cycling at high temperature. The ionic liquid in solution maintains the high maximum operative voltage of the net ionic liquid whereas its viscosity and ionic conductivity are close to those of the conventional Et4NBF4/PC. Furthermore, the presence of propylene carbonate as solvent prevents to some extent the ionic liquid degradation.

New polymer electrolytes based on polyethylene glycol diacrylate–LiBF4–1-ethyl-3-methylimidazolium tetrafluoroborate with the introduction of alkylene carbonates

Polymer gel electrolytes based on polyethylene glycol diacrylate (PEG DA), salt LiBF4, and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) were synthesized and studied in the presence of propylene carbonate and ethylene carbonate as solvents. The mechanism of ionic transport in the system was studied using electrochemical impedance spectroscopy, liquid mass spectrometry, pulse-field-gradient spin echo NMR spectroscopy. The range of operating temperatures of the gel electrolytes was determined by DSC. The total conductivity at room temperature in these systems is about 10–3 S cm–1. The self-diffusion coefficients on 7Li nuclei in the systems with a solvent attain the values about 10–10 m2 s–1, and in the PEG DA–LiBF4–EMIBF4 system they range from 10–13 to 10–12 m2 s–1. Ternary associates [(EMI)2(BF4)]+ and [Li+(BF4)2]– were found by liquid mass spectrometry to be the main charge carriers.

Development of Biosensor for Catechol Using Electrosynthesized Poly(3‐methylthiophene) and Incorporation of LAC Simultaneously

AbstractSimultaneous electropolymerization of 3‐methylthiophene and incorporation of Laccase (LAC) was carried out in the presence of propylene carbonate as a medium by amperometric method. This enzyme modified electrode was used for the sensing of polyphenol. Catechol is taken as a model compound for the study. UV‐Vis spectral studies suggest no denaturation of LAC in presence of propylene carbonate. The SEM studies reveal the surface morphology and incorporation of LAC in P3MT with agglomerated flaky masses are observed in with and without enzyme micrographs. The cyclic voltammograms were recorded for 0.01 mM catechol on plain glassy carbon, polymer and enzyme incorporated electrodes at pH 6.0 and scan rate 50 mV s−1. The fabricated electrochemical biosensor was used for the determination of catechol in aqueous solution by Differential Pulse Voltammetry (DPV) technique. The concentration linear range of 8×10−8 to 1.4×10−5 M a value of MichealisMenten constant Km=7.67 µmol dm−3 and activation energy is 32.75 kJ mol−1. It retains 83 % of the original activity after 60 days which is much higher than that of other biosensors. The developed biosensor was used to quantify catechol in the determination in real samples.

Properties and in vitro characterization of polyhydroxybutyrate–chitosan scaffolds prepared by modified precipitation method

Porous polyhydroxybutyrate (PHB)-chitosan biopolymer scaffolds were prepared by co-precipitation from biopolymer solutions with propylene carbonate and acetic acid as solvents. A change of the fibrous character of chitosan precipitates to globular shaped forms with a polyhydroxybutyrate addition was found in suspensions. Scaffolds differ by porosity and morphology of polymers in microstructures, while chitosan represented more compact plate-like fibers and PHB characterized mainly fine fibrous globular agglomerates. Two structurally dissimilar phase regions were verified in blended scaffolds. A rise in the number of smaller pores, and fine structured polymer forms with PHB content were observed in the scaffolds. A significant reduction in the average molecular weight of biopolymers was found in pure chitosan scaffold, this after precipitation of the chitosan in the presence of propylene carbonate and in blends after mutual biopolymer mixing. Interactions between shortened chitosan chains, PHB and chitosan biopolymers in the blends were observed. An excellent fibroblast proliferation was found in scaffolds prepared from biopolymer blends.

Effect of Propylene Carbonate on Physical Properties of Wood Fibreboard Composite

The effect of propylene carbonate as an accelerator on the mechanical performance and dimensional stability of composites made from wood fibre bonded with wood resin and urea formaldehyde resin was investigated. The results demonstrated that the mechanical performance of the composite fibreboard cured at a relatively low temperature (e.g., 180 °C) could be markedly enhanced by addition of propylene carbonate. Composites cured at higher temperatures (e.g., 200 °C or 220 °C) and/or in presence of propylene carbonate, exceeded the minimum physical properties specified by ANSI-AHA. The addition of 3% propylene carbonate (by weight, based on total fibre and resin content) could optimise the physical properties of the composites. The tensile stress parallel-to-the-surface and the flexural strength and stiffness of the composites increased in presence of propylene carbonate.

Ionic conductivity and physical stability study of gel nework polymer electrolytes

Gel polymer electrolytes (GPE) were prepared by a crosslinking reaction between poly(ethylene glycol) and a crosslinking agent with three isocyanate groups in the presence of propylene carbonate (PC) and ethylene carbonate (EC) or their mixture, and their ionic conducting behavior was carefully investigated. When the plasticizer amount was fixed, the ionic conductivity was greatly influenced by the nature of plasticizers. It was found that the conductivity data followed the Arrhenius equation in the GPE. Whatever plasticizer was used, a maximum ambient conductivity was found at a salt concentration near [Li+]/[EO] equal to 0.20. The physical stability of GPE was studied qualitatively by weight loss of GPE under pressure. It was shown that the stability was greatly affected by the network structure of the GPE and the most stable one in our research was the GPE containing the PEO1000 segment, which has a strong interaction between network and plasticizers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2957–2962, 2000

Ionic conductivity of gel electrolyte based on polydiethylene glycol dimethacrylate and its copolymer

Gel electrolytes were prepared by thermal polymerization of diethylene glycol dimethacrylate (DIEGD) or its copolymer with methoxy polyethylene glycol monomethacrylate, molecular weight 400 (PEM 400), at a molar ratio of 3 1 in the presence of propylene carbonate (PC) and LiClO 4. Conductivity was measured by impedance spectroscopy. It was found that the conductivity data follow the Arrhenius equation in the homopolymer gel system, while the VTF equation holds true in the copolymer gel system. An increase in conductivity was observed in the copolymer gel system. However, whether in the homopolymer or in the copolymer gel system, a maximum ambient temperature conductivity was found at a salt concentration near 1.50 mol l . Further, the activation energy values calculated from Arrhenius plots for the homopolymer gel system tended to reach a minimum value with increasing salt concentration.

Ionic conductivity of polymer gel electrolytes based on poly(polyethylene glycol dimethacrylate)

Gel electrolytes have been prepared by thermal polymerization of poly(polyethylene glycol dimethacrylate) (P(PEGD)) in the presence of propylene carbonate (PC) and alkali metal salts, such as LiClO 4, LiCF 3SO 3 and LiBF 4. The conductivity was studied by means of impedance spectroscopy, and it is found that the temperature dependence of conductivities follow a Arrhenius relationship when the molar percentage of PC is higher than 75% or LiClO 4 concentration is lower than 0.9 mol/l. However, when LiCF 3SO 3 or LiBF 4 is used instead of LiClO 4 as the salt, the situation is different. For LiCF 3SO 3, the Arrhenius relationship almost holds true for all the salt concentrations studied; while for LiBF 4, the Arrhenius equation hardly fits for any salt concentration. The dependence of activation energy on salt concentration is also examined, both for LiClO 4 and LiCF 3SO 3, the values of E a tend to reach a minimum value with increasing salt concentration.

Electrochemical characterization of plasticized-polymer electrolyte based on a polyester of thiodipropionic acid

In this work the preparation and the thermal and electrochemical characteristics of a polymer electrolyte cross-linked in presence of propylenecarbonate as plasticizer and based on polyester of 3,3'-thiodipropionic acid and tri-ethylene glycol with LiCLO 4 are reported. The lithium deposition-stripping process was tested by cyclic voltammetry and the Li/polymer electrolyte interface stability was investigated over time by impedance spectroscopy, and the results are reported and discussed. Cyclability data of a lithium battery operating at 25°C are also reported.

Electrochemical and spectroscopic studies of carbon electrodes in lithium battery electrolyte systems

In this work we studied several parameters that influence the intercalation of lithium ions into carbons (e.g. carbon type, binder and solution composition). The carbons investigated included carbon blacks (e.g. acetylene black, Ketjen black), graphite and carbon fibers. The solvents used in this study include methyl formate, propylene and ethylene carbonate, ethers (e.g. tetrahydrofuran) and their mixtures. The salts included LiClO 4, LiAsF 6 and LiBF 4. CO 2 was tested as an additive. The electrochemical behavior of the electrodes in solutions was followed by chronopotentiometry in galvanostatic charge/discharge cycling and their surface chemistry in solutions was investigated using surface sensitive Fourier-transform infrared spectroscopy (FT-IR) in transmittance, attenuated total reflectance and diffuse reflectance modes. It was found that the solvents and salts are reduced on the carbon electrodes at low potentials to form surface films. In general, their surface chemistry is quite similar to that of lithium or noble metal electrodes at low potential (in the same solutions). The electrochemical behavior of the carbon electrodes in terms of degree of intercalation and its reversibility is strongly affected by their surface chemistry. Reversible intercalation was obtained with graphite in methyl formate solutions containing CO 2. Some degree of reversible intercalation was also obtained with graphite in ethers. The presence of propylene carbonate in solution is detrimental for lithium intercalation in graphite. Reversible lithium-carbon intercalation was also obtained with acetylene black and carbonized polyacrylonitrile. The binder types have a strong impact on the electrode's performance. Preliminary guidelines for optimizing the performance of carbon electrodes as anodes in rechargeable lithium battery are discussed.

A thermodynamic, structural and kinetic study of the electrochemical lithium intercalation into the xerogel V 2O 5 · 1.6 H 2O in a propylene

The electrochemical lithium insertion reaction into the vanadium pentoxide xerogel V 2O 5·.1.6 H 2O (noted VXG) in a propylene carbonate solution has been investigated by structural, thermodynamic and kinetic studies. This material, obtained via a sol-gel process, is a lamellar compound whose high anisotropic structure is characterized by the stacking of ribbons in the c direction. The presence of propylene carbonate in the starting material leads to a basal distance of 21.6 Å (1 Å = 10 −10 m). About 1.8 Li + ions can be accomodated between the ribbons of this lamellar compound at the same energetic level of ~ 3.1 V vs. Li/Li +. Entropy measurements, X-ray diffraction experiments and particle size determinations have given evidence for the existence of two one-phase regions for the composition ranges 0 < x < 0.1 and 0.2 < x < 1.8, and a two phase region for the narrow lithium content 0.1 < x < 0.2. Between x = 0.1 and x = 0.2, lithium insertion causes the removal of the propylene carbonate from the inter-ribbon spacc to give rise to a collapsed VXG form. With a theoretical faradaic capacity of 250 Ah/kg, the reversibility of the lithium insertion process being proven, VXG constitutes a promising intercalation material. Nevertheless, even with a high diffusion coefficient D Li $ ̃ > 5sx 10 −11 cm 2 s −1, its low electronic conductivity hinders utilisation of high current densities. Cycling experiments have shown a satisfactory behaviour since for a current density j = 0.05 mA cm −2, about 70% of the initial capacity, ie. 70 Ah/kg, is recovered after the 30th cycle.