Sulfonic Acid Anion Research Articles

Interionic hydrogen bonds induced high solubility of quinone derivatives and preliminary study on their application properties in all quinone aqueous redox flow battery

The development of highly water-soluble quinone derivatives is an important research direction for aqueous organic redox flow batteries (AORFBs) of high energy density. In this work, choline cations are substituted for sodium ions to form new ion pairs with quinone sulfonates, and the water solubility of quinone sulfonates derivatives is significantly improved due to the formed interionic hydrogen bond between the CO in anthraquinone sulfonic acid anion and -OH in choline cation. Specifically, 9,10-anthraquinone-2-disulfonic choline salt (AQSCH) and 1, 2-dihydroxy-3, 5-phenyldisulfonic acid dicholine salt (BQDS(CH)2) are synthesized by simple ion exchange and acid-base neutralization. As a result, the solubility of the quinone and anthraquinone sulfonates in water is increased by more than ten times, and the redox reversibility is not significantly affected. The charging-discharging performance of a novel pH-neutral all-quinone aqueous battery with AQSCH and BQDS(CH)2 as the anodic and cathodic active electrolytes respectively, choline chloride as the supporting electrolyte is investigated using a static H-type electrolytic cell, the obtained results verifying the feasibility of using choline as the counter cathion and solubilizer of quinone sulfonates to improve their water solubility in pH-neutral AORFBs.

Anion anchored conjugated microporous polymers as solid electrolytes

Improving the actual lithium ion conductivity and transference number of solid electrolytes has always been a bottleneck in the development of high energy density solid-state lithium-ion batteries. Chemically immobilizing anions in the solid electrolytes is the feasible method to remedy this problem. Herein, conjugated microporous polymers (CMP) with the desired designability and functionality were selected as a platform to study the correlation between anion anchor structure and solid electrolyte performance. We designed two types of anion modified CMP (denoted as CMP-SO3Li-1 and CMP-SO3Li-2) with different unit size monomers and they were explored as solid electrolytes in lithium-ion batteries. Both of them delivered high lithium ion migration number around 0.6, and CMP-SO3Li-1 with more abundant sulfonic acid anion exhibited a higher Li+ conductivity than CMP-SO3Li-2, which confirmed that the abundance of sulfonate functional groups was proportional to conductivity. Moreover, LFP|CMP-SO3Li-1|Li and LFP|CMP-SO3Li-2|Li full cells delivered a stable life over 60 cycles at 100 °C, with an initial discharge specific capacity of 143.7 mAh/g and 146.4 mAh/g, respectively. Benefit from the stable electrochemical windows over 4.6 V, CMP-SO3Li-1 also exhibited excellent cell performance with 4 V cathode in LCO|CMP-SO3Li-1|Li and NCM|CMP-SO3Li-1|Li full cells. This strategy of directly covalently riveting anions on the CMP framework has opened an avenue for the development of polymer solid electrolytes with high effective conductivity and migration number, and makes porous organic polymers as a notable potential candidate for solid electrolytes in high-temperature lithium ion batteries.

High energy density of two-dimensional MXene/NiCo-LDHs interstratification assembly electrode: Understanding the role of interlayer ions and hydration

The application of two-dimensional layered hybrid materials in supercapacitor electrodes has high energy density. However, the hybrid assembly and electrochemical energy storage mechanism of multifarious layered electrode materials are still unclear. In this work, a two-dimensional interstratification assembly hybrid electrode by using electrostatic assembly between MXene modified with cetyl trimethylammonium bromide cation (CTAB) and NiCo-LDHs modified with dodecyl benzene sulfonic acid anion (DBS) is presented. As a result, the self-restacking of MXene and NiCo-LDHs nanosheets are effectively prevented, leading to a regular interstratification structure and large interlayer spacing, which accelerate diffusion of electrolyte ions and possess more electrochemical activity sites. The freestanding MXene/NiCo-LDHs electrode displays a much higher specific capacitance of 1207 F g−1 at a scan rate of 0.5 A g−1, an impressive rate capability with 93% capacitance retention after 5000 cycles. Moreover, it shows maximum energy density of 107.3 Wh kg−1 (98.5 mWh cm−3) at a power density of 571 W kg−1 (524 mW cm−3), which is among the highest values reported for MXene and NiCo-LDHs based materials in aqueous electrolytes. This significant electrochemical performance is mainly attributed to hydration of two-dimensional electrodes and exchange or adsorption of interlayer anion-cation.

New Ionic Liquids for Extraction Preconcentration

Review of authors’ works in the field of the use of new ionic liquids (IL), salts of quaternary ammonium cations with carbonic or sulfonic acid anions, in extraction is presented. Properties of IL important for solvent extraction are discussed, and a comparison with the “classical” IL, including substituted imidazolium cations and fluorine-containing anions, is made. The most important applications of IL for the extraction of organic compounds of various classes, including analytical reagents, from aqueous solutions are presented. Data on the extraction of metal ions are presented; various approaches to the use of IL: as “inert” diluents of complexing agents and extraction solvents/extractants active with respect to the extracted substance are discussed. The features and advantages of microextraction with the dispersion of the solvent in IL formed in situ are discussed.

MgO-Templated Mesoporous Carbon As a Catalyst Support for Polymer Electrolyte Fuel Cells

Catalyst poisoning by specific adsorption of the sulfonic acid anion of ionomers has been known as one of the main performance-limiting factors of PEFCs. In a recent study, it was reported that the catalyst poisoning can be suppressed by using a mesoporous carbon (mesoporous carbon nano-dendrites) as a cathode catalyst support [1]. Here, we present that a similar effect can be obtained by using a MgO-templated mesoporous carbon [2] having meso-pores the sizes of which are more-systematically controllable by changing the size of the MgO templates than for conventional carbon supports. An MgO-templated carbon denoted as CNovel® was purchased from Toyo Tanso Inc. The mean diameter of its mesopores is ca. 5 nm (the template MgO size was 5 nm). The sample was graphitized by a heat treatment at 2,100 °C for improving the chemical stability under electrochemical conditions and was crushed by a bead mill to form secondary particles smaller than hundreds nm in size. The obtained powder was immersed in 1 M HNO3 at 80 °C for 1 h to introduce hydrophilic surface groups for facilitating Pt deposition. After thoroughly washing it with pure water, platinum nanoparticles were deposited in aqueous media by using hexahydroxy-platinate as a platinum source. The ORR activity of the prepared catalyst was evaluated by the thin-film RDE method (without ionomers) in aqueous media (0.1 M HClO4) and in MEAs prepared with a Nafion® ionomer (I/C=1.0). The results were compared those of Pt/Vulcan. Figures 1a and 1b show that TEM images of the catalysts. Platinum particles of ca. 2 nm are observed on both the carbons. While Pt/Vulcan shows platinum particles only on the outer edge of the carbon particle, Pt/CNovel shows platinum particles not only on the outer edge but also on the mesopores inside the carbon particle. Figure 1c shows the I-V curves of MEAs using Pt/CNovel and Pt/Vulcan. Pt/CNovel exhibits higher cell-voltage than Pt/Vulcan in the low current density region. This result indicates that the former has a higher ORR activity than the latter as specifically indicated in the specific activities at 0.9 V shown in Figure 1d. The trend is, however, opposite in the RDE measurements while the specific activities for both samples by RDE are higher than those measured by the MEAs. These results indicate that the Pt/CNovel suffers less catalyst poisoning by the sulfonic acid anion than Pt/Vulcan in MEAs probably because the anion linked to the ionomer cannot reach the surfaces of the Pt nanoparticles inside the mesopores of CNovel while all Pt nanoparticles on Vulcan® can be reached by the ionomer.

Sulfonated Polymerized Ionic Liquid Block Copolymers.

The successful synthesis of a new diblock copolymer, referred to as sulfonated polymerized ionic liquid (PIL) block copolymer, poly(SS-Li-b-AEBIm-TFSI), is reported, which contains both sulfonated blocks (sulfonated styrene: SS) and PIL blocks (1-[(2-acryloyloxy)ethyl]-3-butylimidazolium: AEBIm) with both mobile cations (lithium: Li(+) ) and mobile anions (bis(trifluoromethylsulfonyl)imide: TFSI(-) ). Synthesis consists of polymerization via reversible addition-fragmentation chain transfer, followed by post-functionalization reactions to covalently attach the imidazolium cations and sulfonic acid anions to their respective blocks, followed by ion exchange metathesis resulting in mobile Li(+) cations and mobile TFSI(-) anions. Solid-state films containing 1 m Li-TFSI salt dissolved in ionic liquid result in an ion conductivity of >1.5 mS cm(-1) at 70 °C, where small-angle X-ray scattering data indicate a weakly ordered microphase-separated morphology. These results demonstrate a new ion-conducting block copolymer containing both mobile cations and mobile anions.

Influence of dopant anions on properties of polypyrrole nanocoated poly(styrene- co-methacrylic acid) particles

Nanostructures of polypyrrole (PPy) were synthesized on poly(styrene- co-methacrylic acid) particles with iron (III) p-toluensulfonate hexahydrate (FeTS), sodium p-toluensulfonate (NaTS), 5-sulfosalicylic acid dihydrate (SSA), iron(III) chloride hexahydrate or p-toluensulfonic acid (TSA) as dopants. A doping level between 0.25 and 0.29 in all samples was determined by X-ray photoelectron spectroscopy (XPS). FTIR analysis shows the effective covering of core samples and that no degradation of PPy has taken place. Conductivity decay study establishes that aromatic sulfonic acid anions provide better performance to the conducting polymer when are present as the only dopants. The chloride anions have a detrimental effect over conductivity and stability of the PPy shell.

Template mediated formation of shaped polypyrrole particles

The formation of different micro- and nanostructures during the chemical synthesis of polypyrrole is reviewed shortly based on the conceptions of hard- and soft-templating models. Contrary to other models that emphasize the role of micelles it is found here that during the oxidative polymerization of pyrrole using sulfonic acid dopants a crystalline hard template is found in the first steps of the reaction before the addition of the oxidant. This template is formed by a complex consisting of 2,5-bis(pyrrole-2-yl)pyrrolidine and the sulfonic acid anion. The acid catalyzed formation of this specific tripyrrole is discussed.

Origin of templating processes in polypyrrole synthesis

The supermolecular mechanism of the template-mediated oxidative polymerization of pyrrole is investigated in detail. It is shown for the first time that 2,5-bis(pyrrol-2-yl)pyrrolidyl complexes with aromatic sulfonic acids such as β-naphtalenesulfonic acid or para-toluenesulfonic acid are formed in the early polymerization step. The crystalline acid–base complexes are isolated and their crystal structures are analyzed. A 2,5-bis(pyrrol-2-yl)pyrrolidyl cation is common to both complexes and forms an inner salt with the sulfonic acid anion. As concluded from NMR investigations the synthesis using sulfonic acids results in a high stereo selectivity with respect to the trans conformation of the pyrrolidyl ring compared with the classical synthesis routine of this compound using hydrochloric acid. The needle-like crystals of the complexes act as hard templates during the next step of the polymerization and result in tubular morphologies of the polypyrrole.

Molecular dynamics simulation of the structure of an ion-conducting PEO-based solid polymer electrolyte

Proton-conducting solid polymer electrolyte containing poly(ethylene oxide) sulfonic acid anions (PEO) cations and 35 wt% of water is constructed by atomistic molecular modelling. The structure of the PEO sulfonic acid anions and PEO was studied by calculating the dihedral angle distributions, intramolecular pair correlation functions between the carbon atoms and ether oxygen atoms and by performing the conformational triads population analysis and dimension analysis. The results were compared with the results obtained for similar non-conducting systems and for the system containing only one PEO sulfonic acid anion in water. Some differences were found in the structures. However, the differences in the structures of the polymers were not able to explain the conductivity behaviour of the systems. Instantaneous coordination of cations was studied to get a detailed view of the local environment of the cations. The local environment of the cations shows many variations in the studied systems. Small microphase separation in the conducting system was found.

Theoretical Studies of Proton Transfer in Water and Model Polymer Electrolyte Systems

The interactions of H3O+ with water and model Nafion structures are studied using ab initio, density functional theory, and molecular dynamics simulations. In the gas phase, H3O+ is solvated by a well-defined first solvation shell with three water molecules, while an additional water molecule locates in the second shell. This same structure is preferred in the liquid phase. In the absence of an electric field, proton transfer between H3O+ and a water molecule proceeds without barrier if the hydrogen bond length O−H···O is smaller than 2.7 A. When an electric field is applied in a direction opposite to that of the system dipole, the activation barrier for proton transport is significantly reduced. The Nafion side chain, ending in a sulfonic group, is folded in the gas phase, whereas in aqueous media, it becomes stretched, and proton transfer takes place from the acid group to the water molecules. Results from MD simulations indicate that the contact ion pair formed between the sulfonic acid anion −SO3- and...

Estimation of the ion conductivity of a PEO-based polyelectrolyte system by molecular modeling

Atomistic molecular modeling has been used to construct amorphous 35.0 wt% water-containing polymer electrolyte materials consisting of two polymers: poly(ethylene oxide) (PEO) and poly(ethylene oxide) with sulfonic acid anion end groups (PEO sulfonic acid anion). The cations in the system are the hydronium ion, which simulates the classical diffusion of the hydronium ion and a particle called proton, which simulates the proton hopping mechanism. The possibility of the ions to move together with the polymers in the matrix is also discussed. The coordination between the ions were calculated and compared with the results for similar systems having different amounts of water. The diffusion coefficients for the ions and the conductivity of the system were calculated. The system was found to be conducting, which agrees with the experimental work. In the simulation, both the hopping and the diffusion mechanism were important in the studied system, while in the simulated system, which contains only one PEO sulfonic acid anion in water, the hopping mechanism dominated. The good correlation between the experimental and simulated results shows that the used model is able to estimate whether the material is conducting or non-conducting. The model can also offer interesting information concerning the possible mechanisms of proton conductivity in polymer electrolyte materials.

Effect of Molecular Interactions on Solubility of Polypyrrole

Molecular interactions in polypyrrole (PPy) doped with dodecylbenzene sulfonic acid anion were studied as a key factor affecting solubility of the polymer. The bulky dopant molecules are able to restrain the molecular interactions in as-polymerized PPy, but molecular interaction increases gradually as time elapses, causing insolubilization of PPy powder. Insolubilization results mainly from a formation of crosslinks between polymer chains.

Molecular dynamics simulation of the PEO sulfonic acid anion in water

Atomistic molecular modeling has been used to study the sulfonic acid anion of poly(ethylene oxide) (PEO sulfonic acid anion) in vacuum and a polymer electrolyte system consisting of the PEO sulfonic acid anion in water. The vibrational spectra of the molecules were simulated by the local mode method and found to be in good agreement with the experimental IR and Raman spectra. The structure of PEO sulfonic acid anion was studied in vacuum and water and compared to the structure of an isolated PEO sulfonic acid in vacuum. The simulated value for the root mean square end-to-end distance for the PEO sulfonic acid anion was 22Å in vacuum and 12Å in water. The root mean square radius of gyration of the PEO sulfonic acid anion was 8.4Å in vacuum and 5.6Å in water. The PEO sulfonic acid anion was randomly coiled in water and in an extended shape in vacuum.

Simulation of a PEO based solid polyelectrolyte, comparison of the CMM and the Ewald summation method

Modeling of polyelectrolytes is very time consuming because of the strong long-range interactions between ions. Traditionally the Ewald summation method is used to calculate the non-bonding Van der Waals and Coulombic interactions. Recently a new much faster method called the cell multipole method (CMM), has been developed to model the non-bonding interactions. The use of the CMM makes the calculations dramatically faster compared to the duration of the calculation when the Ewald summation method is used. In this paper we compare the results of a spectral analysis, pair correlation study and dihedral angle study made for a solid amorphous polyelectrolyte by using both the Ewald summation method and the CMM. The simulated system contained poly(ethylene oxide) sulfonic acid anions, poly(ethylene oxide) (PEO), cations and water. There was no remarkable difference between the results obtained by using Ewald summation method or the CMM. Thus in future the calculations of similar systems can be made applying the fast CMM.

Modeling of water-free and water containing solid polyelectrolytes

Atomistic molecular modeling was used to construct water-free and water-containing polymer electrolyte materials consisting of poly(ethylene oxide) (PEO), poly(ethylene oxide) with sulfonic acid anion end groups (PEO sulfonic acid anion) and cations. The coordination and the diffusion of the ions and water was studied and compared with experimental results of similar systems and the simulated results of a system containing only PEO sulfonic acid anion and cations in water. The coordination found in the systems was largely in accordance with the experimental results. The influence of the PEO and water concentration of the system on the coordination is discussed. The systems were not conducting, which also applies to similar real water-free materials. The good correlation between the experimental and simulated results shows, that the model may give atomistic information for evaluating new polyelectrolyte materials.

Modelling a polyelectrolyte system in water to estimate the ion-conductivity

Atomistic molecular modelling has been utilized to construct a proton-conducting polymer electrolyte system consisting of poly(ethylene oxide) sulfonic acid anion (PEO sulfonic acid anion), water, hydronium ion and proton in an amorphous cell. The force field was parametrized to simulate proton transport as accurately as possible in an atomistic model. The coordination study was made and found to be mainly in accordance with experimental data. The diffusion coefficients for the PEO sulfonic acid anion, water, the proton and for the hydronium ion were determined. The ion conductivities of the whole system and of the ions were estimated and found to be in accordance with experimental values. The good correlation between the experimental and simulated results shows that the used model may provide guidance for evaluating new materials by experimentalists.

Vibrational spectra as experimental probes for molecular models of ion-conducting polyether systems

Atomistic molecular modelling has been used to construct polymer electrolyte materials consisting of poly(ethylene oxide) (PEO), poly(ethylene oxide) with sulfonic acid end groups (PEO sulfonic acid) and water in an amorphous cell with periodic boundary conditions. A conformational analysis of PEO sulfonic acid was made using the PCFF forcefield, and for one linkage also the CVFF forcefield was used in molecular mechanics calculations. In addition, the energy contour map for the bond connecting the sulfonic acid group to the polyether chain and the next carbon—carbon bonds was constructed using RIS theory. The results obtained with the different forcefields were fairly similar. For all linkages several minima with low energy barriers were found. The relative energies of the minima vary very little. The maxima are due to steric effects. The conclusion is drawn that all rotations in PEO sulfonic acid are restricted at room temperature. Two polymer electrolyte systems were constructed, one water-free, and one containing water. The relevance of the model, and the most suitable forcefield, were tested by comparing the calculated vibrational spectra with experimental i.r. and Raman spectra. Very good agreement between measured and calculated vibrational frequencies was found with both forcefields for the modes attributed to the PEO chain. There was a significant difference between values for the SO stretch calculated with the CVFF forcefield and in the PCFF forcefield, respectively. Since the SO stretch calculated with the PCFF forcefield corresponds very well with literature values, the conclusion was drawn that the PCFF forcefield is better suited to model PEO sulfonic acid than is the CVFF forcefield. In the modelling studies, hydrogen bonds between the sulfonic acid group and water molecules were formed. In the experimental system an absorption was found which is attributed to a hydronium sulfonate ion pair. The correlation of this finding with experimental measurements of water transport in proton-conducting membranes is discussed. The proton coordination study shows that the model can be developed by adding sulfonic acid anions to the amorphous cell. The model will be further developed for studies of proton conducting mechanisms.

Polymerization in preoriented media: Polymerization rate of p‐styrene sulfonic acid on poly(cationic) backbones

AbstractMany important naturally occurring biochemical reactions such as synthesis of nucleic acids, proteins, and polysaccharides proceed through template polymerization. Such reactions are very complex, and the study of simpler systems is of great interest.A radical initiated polymerization of p‐styrene sulfonic acid anion attached to a poly(quaternary ammonium) backbone (ionene) was studied. The polycationic matrix was prepared from 1–4 diazobi‐cyclo (2.2.2.) octane and 1–4 dibromobutane. It was of low molecular weight (5–10 monomeric units), high rigidity, and could be considered to be in a rod‐like conformation in dilute water solutions. The polymerization of the pSSA‐ionene complex was followed by means of ultraviolet spectroscopy. The overall polymerization kinetics was studied as a function of temperature, concentrations of monomer and initiator, and of the “degree of filling” of the matrix at neutral pH. A rate increase of over two orders of magnitude was observed in the presence of the matrix. This effect was maximum for stoichiometric amounts of monomer and matrix and fell off rapidly for lower monomer‐to‐matrix ratios. The kinetic effect is accompanied by a large decrease in the overall activation energy by 6 kcal/mol.