Littérature scientifique sur le sujet « Polymer Electrolytes - Ion Dynamics »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Sommaire
Consultez les listes thématiques d’articles de revues, de livres, de thèses, de rapports de conférences et d’autres sources académiques sur le sujet « Polymer Electrolytes - Ion Dynamics ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Articles de revues sur le sujet "Polymer Electrolytes - Ion Dynamics"
1
Mabuchi, Takuya, Koki Nakajima et Takashi Tokumasu. « Molecular Dynamics Study of Ion Transport in Polymer Electrolytes of All-Solid-State Li-Ion Batteries ». Micromachines 12, no 9 (26 août 2021) : 1012. http://dx.doi.org/10.3390/mi12091012.
Texte intégralRésumé :
Atomistic analysis of the ion transport in polymer electrolytes for all-solid-state Li-ion batteries was performed using molecular dynamics simulations to investigate the relationship between Li-ion transport and polymer morphology. Polyethylene oxide (PEO) and poly(diethylene oxide-alt-oxymethylene), P(2EO-MO), were used as the electrolyte materials, and the effects of salt concentrations and polymer types on the ion transport properties were explored. The size and number of LiTFSI clusters were found to increase with increasing salt concentrations, leading to a decrease in ion diffusivity at high salt concentrations. The Li-ion transport mechanisms were further analyzed by calculating the inter/intra-hopping rate and distance at various ion concentrations in PEO and P(2EO-MO) polymers. While the balance between the rate and distance of inter-hopping was comparable for both PEO and P(2EO-MO), the intra-hopping rate and distance were found to be higher in PEO than in P(2EO-MO), leading to a higher diffusivity in PEO. The results of this study provide insights into the correlation between the nanoscopic structures of ion solvation and the dynamics of Li-ion transport in polymer electrolytes.
2
Kumar, Asheesh, Raghunandan Sharma, M. Suresh, Malay K. Das et Kamal K. Kar. « Structural and ion transport properties of lithium triflate/poly(vinylidene fluoride-co-hexafluoropropylene)-based polymer electrolytes ». Journal of Elastomers & ; Plastics 49, no 6 (4 novembre 2016) : 513–26. http://dx.doi.org/10.1177/0095244316676512.
Texte intégralRésumé :
Polymer electrolytes consisting of poly(vinylidene fluoride-co-hexafluoropropylene) in combination with lithium triflate (LiCF3SO3) salt of varying concentration have been prepared using the conventional solution casting technique in the argon atmosphere. Structural electrical characterizations of the synthesized electrolytes have been performed using various imaging and spectroscopic techniques. The DC conductivities determined by complex impedance plots reveal gradual increase with increase in salt concentration up to a particular limit and decrease subsequently. The maximum DC conductivity obtained at 300 K is 1.64 × 10−4 Scm−1 for the electrolyte with a polymer to salt weight ratio of 1:1.8. The temperature-dependent conductivity followed a mixed Arrhenius and Vogel–Tamman–Fulcher type behaviour for the polymer electrolytes. From the Summerfield master curve plot, the conductivity of the solid polymer electrolytes is found to depend not only on ion dynamics but also on the segmental mobility of the polymer chains.
3
Yusof, S. Z., H. J. Woo et A. K. Arof. « Ion dynamics in methylcellulose–LiBOB solid polymer electrolytes ». Ionics 22, no 11 (25 mai 2016) : 2113–21. http://dx.doi.org/10.1007/s11581-016-1733-y.
Texte intégral
4
Garaga, Mounesha N., Sahana Bhattacharyya et Steve G. Greenbaum. « Achieving Enhanced Mobility of Ions in Ionic Liquid-Based Gel Polymer Electrolytes By Incorporating Inorganic Nanofibers for Li-Ion Battery ». ECS Meeting Abstracts MA2022-02, no 2 (9 octobre 2022) : 160. http://dx.doi.org/10.1149/ma2022-022160mtgabs.
Texte intégralRésumé :
Polymer electrolytes have received much attention in Li-ion battery research because of their unique properties, such as, high ionic conductivity, high mechanical strength including good electrode-electrolyte contact. A major research has been focused on improving the conductivity while retaining the mechanical stability of polymer electrolytes. In this context, ionic liquid-based gel polymer electrolytes are an excellent candidate. A detailed NMR investigation of PMMA-ILs gels electrolytes probing the structure and dynamics of ions was recently reported.[1] The presence of ILs in polymer matrix not only improves the conductivity but also enhances the self-healing capability. In another study, self-healing capability that reduces the dendrite formation at the interface has been discovered, for example, in PVDF-HFP-ILs electrolyte.[2] In this regard, this work reports the possible ways to enhance the ionic conductivity of such polymer electrolyte further by adding Al2O3 nanofibers. A series of PVDF-HFP-ILs with 1M LiTFSI in EMIMTFSI at different ratios of Al2O3nanofibers were prepared through solution cast technique. The dynamics of ions confined within polymer-Al2O3 matrix was explored through Impedence and PFG NMR spectroscopy. The amorphocity and the distribution of Al2O3 nanofibers are studied through XRD and SEM-EDX analyses. Lastly, the local structure of ions and their interaction with polymer and Al2O3 nanofibers were established through a detailed solid-state NMR analyses detecting 1H, 27Al, 13C, 19F, 7Li nuclei including 2D 13C{1H} HETCOR experiments. A reasonable enhancement in terms of ionic conductivity was observed with the addition of Al2O3 nanofibers, which improves the conducting pathways within the polymer network. [1] M. N. Garaga, N. Jayakody, C. C. Fraenza, B. Itin, and S. Greenbaum, Journal of Molecular Liquids 329, 115454 (2021). [2] T. Chen, W. Kong, Z. Zhang, L. Wang, Y. Hu, G. Zhu, R. Chen, L. Ma, W. Yan, Y. Wang, J. Liu, and Z. Jin, Nano Energy 54, 17 (2018).
5
Peters, Brandon L., Zhou Yu, Paul C. Redfern, Larry A. Curtiss et Lei Cheng. « Effects of Salt Aggregation in Perfluoroether Electrolytes ». Journal of The Electrochemical Society 169, no 2 (1 février 2022) : 020506. http://dx.doi.org/10.1149/1945-7111/ac4c7a.
Texte intégralRésumé :
Electrolytes comprised of polymers mixed with salts have great potential for enabling the use of Li metal anodes in batteries for increased safety. Ionic conductivity is one of the key performance metrics of these polymer electrolytes and achieving high room-temperature conductivity remains a challenge to date. For a bottom-up design of the polymer electrolytes, we must first understand how the structure of polyelectrolytes on a molecular level determines their properties. Here, we use classical molecular dynamics to study the solvation structure and ion diffusion in electrolytes composed of a short-chain perfluoroether with LiFSI or LiTFSI salts. Density functional theory is also used to provide some insights into the structures and energies of the salt interactions with the perfluoroether. We observe the formation of aggregates of salts in the fluorinated systems even at low salt concentrations. The fluorine-fluorine attraction in the solvent is the governing factor for creating the salt aggregates. The aggregates’ size and lifetime change with concentration and anion. These simulations provide an insight into the structure and dynamics of perfluoroether based electrolytes that can be used to improve Li-ion batteries.
6
Park, Habin, Anthony Engler, Nian Liu et Paul Kohl. « Dynamic Anion Delocalization of Single-Ion Conducting Polymer Electrolyte for High-Performance of Solid-State Lithium Metal Batteries ». ECS Meeting Abstracts MA2022-02, no 3 (9 octobre 2022) : 227. http://dx.doi.org/10.1149/ma2022-023227mtgabs.
Texte intégralRésumé :
Lithium metal batteries (LMBs) have been considered as next-generation energy storages due to their extremely high theoretical specific capacity (3860 mAh g-1). However, current LMBs, using conventional liquid electrolytes, still could not fulfill the demand of soaring expansion of energy era, such as electrical vehicles, because of their safety issues, originated by uncontrollable electrolytic side reaction on the lithium, resulting unstable solid-electrolyte interphase (SEI) and vicious lithium dendritic growth [1]. Also, carbonate-based liquid electrolytes have an intrinsic flammability, and the lithium dendrite, which short-circuits a cell, can lead to severe safety hazard with the unfavorable flammability of current liquid system when they are ignited. Therefore, solid-state electrolytes have been spotlighted recently for a pathway for safe, and high energy and power LMBs, due to their superior thermal stability and low vapor pressure, while maintaining suitable electrolytic performances. In this study, solid-state single-ion conducting polymer electrolytes (SICPEs), utilizing dynamic anion delocalization (DAD), realizing high ionic conductivity and dimensional stability for high-performance LMB, are studied. The SICPEs enable superior lithium transference number, resulting in highly reduced concentration gradient of lithium cation along the electrolyte to suppress the undesirable lithium dendritic growth. However, SICPEs have prominently lower ionic conductivity than dual-ion conducting polymer electrolyte (DICPEs), which is a critical issue to make a slower charge/discharge for SICPEs [2]. Although an approach utilizing gel polymer electrolyte (GPE), using a liquid solvent as a plasticizer, has been exploited to increase the ionic conductivity of SICPEs, GPEs have struggled with lower mechanical stability, compared to solid state, and still existing flammability issue with the plasticizer. The novel plasticizer, which is described here, can interact with bulky anionic polymer matrix, so that the negative charge can be dispersed onto the whole complex by DAD. Once the bulky complex is formed by DAD, the dissociation of lithium cation from anionic matrix can be easier with the decreased activation energy and higher ionic conduction. While increasing the ionic conductivity with DAD, the nature of polymeric plasticizer will highly suppress flammability. DAD allows the membrane endure more tensile strength due to the dynamic structural change in crosslinking state, so that the polymer electrolyte can tolerate dendritic growth of lithium by morphological change on an electrode surface. The obvious advantages of DAD-induced solid polymer electrolytes in this study for a high energy and power, and ultra-safe LMB can present a novel approach of polymer electrolyte design to the astronomical demand of energy storages. [1] F. Ahmed, I. Choi, M.M. Rahman, H. Jang, T. Ryu, S. Yoon, L. Jin, Y. Jin, W. Kim, ACS Appl. Mater. Interfaces 2019, 11, 34930-34938. [2] D.-M. Shin, J.E. Bachman, M.K. Taylor, J. Kamcev, J.G. Park, M.E. Ziebel, E. Velasquez, N.N. Jarenwattananon, G.K. Sethi, Y. Cui, J.R. Long, Adv. Mater. 2020, 32, 1905771.
7
Dennis, John Ojur, Abdullahi Abbas Adam, M. K. M. Ali, Hassan Soleimani, Muhammad Fadhlullah Bin Abd Shukur, K. H. Ibnaouf, O. Aldaghri et al. « Substantial Proton Ion Conduction in Methylcellulose/Pectin/Ammonium Chloride Based Solid Nanocomposite Polymer Electrolytes : Effect of ZnO Nanofiller ». Membranes 12, no 7 (13 juillet 2022) : 706. http://dx.doi.org/10.3390/membranes12070706.
Texte intégralRésumé :
In this research, nanocomposite solid polymer electrolytes (NCSPEs) comprising methylcellulose/pectin (MC/PC) blend as host polymer, ammonium chloride (NH4Cl) as an ion source, and zinc oxide nanoparticles (ZnO NPs) as nanofillers were synthesized via a solution cast methodology. Techniques such as Fourier transform infrared (FTIR), electrical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV) were employed to characterize the electrolyte. FTIR confirmed that the polymers, NH4Cl salt, and ZnO nanofiller interact with one another appreciably. EIS demonstrated the feasibility of achieving a conductivity of 3.13 × 10−4 Scm−1 for the optimum electrolyte at room temperature. Using the dielectric formalism technique, the dielectric properties, energy modulus, and relaxation time of NH4Cl in MC/PC/NH4Cl and MC/PC/NH4Cl/ZnO systems were determined. The contribution of chain dynamics and ion mobility was acknowledged by the presence of a peak in the imaginary portion of the modulus study. The LSV measurement yielded 4.55 V for the comparatively highest conductivity NCSPE.
8
George, Sweta Mariam, Debalina Deb, Haijin Zhu, S. Sampath et Aninda J. Bhattacharyya. « Spectroscopic investigations of solvent assisted Li-ion transport decoupled from polymer in a gel polymer electrolyte ». Applied Physics Letters 121, no 22 (28 novembre 2022) : 223903. http://dx.doi.org/10.1063/5.0112647.
Texte intégralRésumé :
We present here a gel polymer electrolyte, where the Li+-ion transport is completely decoupled from the polymer host solvation and dynamics. A free-standing gel polymer electrolyte with a high volume content (nearly 60%) of xM LiTFSI in G4 (tetraglyme) ( x = 1–7; Li+:G4 = 0.2–1.5) liquid electrolyte confined inside the PAN (polyacrylonitrile)-PEGMEMA [poly (ethylene glycol) methyl ether methacrylate oligomer] based polymer matrix is synthesized using a one-pot free radical polymerization process. For LiTFSI concentrations, x = 1–7 (Li+:G4 = 0.2–1.5), Raman and vibrational spectroscopies reveal that like in the liquid electrolyte, the designed gel polymer electrolytes (GPEs) also show direct coordination of Li+-ions with the tetraglyme leading to the formation of [Li(G4)]+. Coupled with the spectroscopic studies, impedance and nuclear magnetic resonance investigations also show that the ion transport is independent of the polymer segmental motion and is governed by the solvated species {[Li(G4)]+}, very similar to the scenario in ionic liquids. As a result, the magnitude of ionic conductivity and activation energies of the gel polymer electrolyte are very similar to that of the liquid electrolyte. The Li+-ion transport number for the GPE varied from 0.44 ( x = 1) to 0.5 ( x = 7) with the maximum being 0.52 at x = 5.
9
Caradant, Lea, Nina Verdier, Gabrielle Foran, David Lepage, Arnaud Prébé, David Aymé-Perrot et Mickaël Dollé. « The Influence of Polar Functional Groups in Hot-Melt Extruded Polymer Blend Electrolytes for Solid-State Lithium Batteries ». ECS Meeting Abstracts MA2022-01, no 2 (7 juillet 2022) : 210. http://dx.doi.org/10.1149/ma2022-012210mtgabs.
Texte intégralRésumé :
Following the COP26 Summit in November 2021, more than hundred countries pledged to reach zero-emission by 2070 at the latest and the major car manufacturers committed to selling only electric vehicles by 2040. Currently, lithium-ion batteries (LIBs) are among the most widely used storage systems because of their high energy and power densities and long lifespan.1 The early LIBs are composed of intercalation electrodes, electronically isolated by an ion-conducting organic liquid electrolyte. However, the use of liquid electrolytes presents some disadvantages – especially in regard to consumer safety – related to short-circuits and potential leakages of the flammable liquid solvent. Moreover, in the case of lithium metal batteries, the combination of a liquid electrolyte and a high-capacity lithium metal anode leads to the uncontrolled deposition of lithium during the reduction, forming dendrites between the electrodes. A promising way to avoid this instability and improve battery safety is to replace the liquid electrolyte with an ion-conducting solid electrolyte.2 Among them, solid polymer electrolytes (SPEs) represent one of the most attractive alternatives due to their capacity to effectively conduct ions and higher mechanical resistance than their liquid counterparts.3 An important criterion for selecting polymers for use in SPEs is their ability to dissolve lithium salts through polar functional groups. Salt dissolution results in the replacement of ion-ion interactions in the lithium salt, with ion-dipole interactions in the polymer. The transport mechanisms of these ion-conducting materials differ from those of liquid electrolytes. Cation transport in polymer involves two steps which are considered to be dissociated or not, depending on the model chosen (Arrhenius or Vogel-Fulcher-Tammann, respectively). The application of one of these models provides interesting information on the ionic mobility dynamics in SPEs and, in particular, on the interplay between ionic jumps and polymer chain mobility. In the Arrhenius model, ionic jumps occur between coordinating sites, without taking into account the influence of segmental relaxation. Conversely, the VTF equation implies a strong relationship between these parameters. According to previous studies, higher segmental motions in the amorphous phase of polymers mainly provide ionic transport, which explains the limited ionic conductivity of SPEs at ambient temperature (less than 10-5 S/cm). Another major limitation of SPEs is primarily related to their dual role as electrolyte and binder in composite electrodes, which requires contradictory requirements to be met. Indeed, SPEs must have both sufficient flexibility to allow good interfacial contact between the electrode components and sufficient rigidity to limit short circuits. Polymer blending has emerged as an economic and effective technique to develop new SPEs which may simultaneously combine properties of each polymer and control the intrinsic properties of the resulting blend by adjusting the formulation.4 Moreover, polymer blends can be obtained by a solvent-free processing method, which reduce SPE toxicity and production time (no solvent evaporation). However, polymer blending makes both the salt dissociation processes and the ionic transport more difficult to understand as both polymers can dissolve lithium salts with their polar functional groups. Each polymer has different ionic transport properties depending on its architecture and thermal properties. Currently, no systematic survey comparing the ability of polymers with various functional groups to dissolve lithium salts in blends has thus far been conducted. In this presentation, we will discuss the salt dissociation ability of polar functional groups in various polymer blend SPEs. These groups are limited to those that are most commonly present in SPEs : ether, nitrile, carbonate, ester, alcohol and amide.5 The blends presented have been obtained by extrusion, which allows the effect of solvents on salt/polymer interactions to be neglected. In this work, coupled FTIR, EDX and 7Li NMR analyses allow the interactions between LiTFSI and the polymer blends to be determined with a good degree of certainty. Our original study combines experimental and theoretical approaches to determine effects of polymers’ lithium salt solvating ability on polymer blend electrolyte properties and represents an advancement in understanding and optimizing polymer selection for SPEs, used in lithium-ion batteries. References Xie, W., Liu, X., He, R., Li, Y., Gao, X., Li, X., Peng, Z., Feng, S., Feng, X. and Yang, S. Journal of Energy Storage 2020, 32, 101837. Chen, R., Qu, W., Guo, X., Li, L. and Wu, F. Materials Horizons 2016, 3, 487-516. Gray, F. M. Solid polymer electrolytes, VCH New Tork 1991. Caradant, L., Lepage, D., Nicolle, P., Prébé, A., Aymé-Perrot, D. and Dollé, M. ACS Applied Polymer Materials 2020, 4943-4951. Caradant, L., Verdier, N., Foran, G., Lepage, D., Prébé, A., Aymé-Perrot, D. and Dollé, M. ACS Applied Polymer Materials 2021. Figure 1
10
Caradant, Lea, Nina Verdier, Gabrielle Foran, David Lepage, Arnaud Prébé, David Aymé-Perrot et Mickaël Dollé. « The Influence of Polar Functional Groups in Melt-Blended Polymers Used As New Solid Electrolytes for Lithium Batteries. » ECS Meeting Abstracts MA2022-02, no 7 (9 octobre 2022) : 2423. http://dx.doi.org/10.1149/ma2022-0272423mtgabs.
Texte intégralRésumé :
Following the COP26 Summit in November 2021, more than hundred countries pledged to reach zero-emission by 2070 at the latest and the major car manufacturers committed to selling only electric vehicles by 2040. Currently, lithium-ion batteries (LIBs) are among the most widely used storage systems because of their high energy and power densities and long lifespan.1 The early LIBs are composed of intercalation electrodes, electronically isolated by an ion-conducting organic liquid electrolyte. However, the use of liquid electrolytes presents some disadvantages – especially in regard to consumer safety – related to short-circuits and potential leakages of the flammable liquid solvent. Moreover, in the case of lithium metal batteries, the combination of a liquid electrolyte and a high-capacity lithium metal anode leads to the uncontrolled deposition of lithium during the reduction, forming dendrites between the electrodes. A promising way to avoid this instability and improve battery safety is to replace the liquid electrolyte with an ion-conducting solid electrolyte.2 Among them, solid polymer electrolytes (SPEs) represent one of the most attractive alternatives due to their capacity to effectively conduct ions and higher mechanical resistance than their liquid counterparts.3 An important criterion for selecting polymers for use in SPEs is their ability to dissolve lithium salts through polar functional groups. Salt dissolution results in the replacement of ion-ion interactions in the lithium salt, with ion-dipole interactions in the polymer. The transport mechanisms of these ion-conducting materials differ from those of liquid electrolytes. Cation transport in polymer involves two steps which are considered to be dissociated or not, depending on the model chosen (Arrhenius or Vogel-Tamman-Fulcher, respectively). The application of one of these models provides interesting information on the ionic mobility dynamics in SPEs and, in particular, on the interplay between ionic jumps and polymer chain mobility. According to previous studies, higher segmental motions in the amorphous phase of polymers mainly provide ionic transport, which explains the limited ionic conductivity of SPEs at ambient temperature (less than 10-5 S/cm). Another major limitation of SPEs is primarily related to their dual role as electrolyte and binder in composite electrodes, which requires contradictory requirements to be met. Indeed, SPEs must have both sufficient flexibility to allow good interfacial contact between the electrode components and sufficient rigidity to limit short circuits. Polymer blending has emerged as an economic and effective technique to develop new SPEs which may simultaneously combine properties of each polymer and control the intrinsic properties of the resulting blend by adjusting the formulation.4 Moreover, polymer blends can be obtained by a solvent-free processing method, which reduce SPE toxicity and production time and cost. However, polymer blending makes both the salt dissociation processes and the ionic transport more difficult to understand as both polymers can dissolve lithium salts with their polar groups. Each polymer has different ionic transport properties depending on its architecture and thermal properties. Currently, no systematic survey comparing the ability of polymers with various functional groups to dissolve lithium salts in blends has thus far been conducted. In this presentation, we will discuss the salt dissociation ability of polar functional groups in various polymer blend SPEs. These groups are limited to those that are most commonly present in SPEs : ether, nitrile, carbonate, ester, alcohol and amide.5 The blends presented have been obtained by extrusion, which allows the effect of solvents on salt/polymer interactions to be neglected. Coupled FTIR, EDX and 7Li NMR analyses allow the interactions between LiTFSI and the polymer blends to be determined with a good degree of certainty. Our original study combines experimental and theoretical approaches to determine effects of polymers’ lithium salt solvating ability on blend electrolyte properties. Finally, this survey highlights an ideal polymer couple with the most promising and complementary properties, usable as SPE for LIBs. Indeed, this blend presents encouraging properties, compared to single-polymer SPEs, such as higher ionic conductivities over a wide temperature range, as well as improved mechanical and thermal stability properties and cycling performances. References Xie, W., Liu, X., He, R., Li, Y., Gao, X., Li, X., Peng, Z., Feng, S., Feng, X. and Yang, S. Journal of Energy Storage 2020, 32, 101837. Chen, R., Qu, W., Guo, X., Li, L. and Wu, F. Materials Horizons 2016, 3, 487-516. Gray, F. M. Solid polymer electrolytes, VCH New Tork 1991. Caradant, L., Lepage, D., Nicolle, P., Prébé, A., Aymé-Perrot, D. and Dollé, M. ACS Applied Polymer Materials 2020, 4943-4951. Caradant, L., Verdier, N., Foran, G., Lepage, D., Prébé, A., Aymé-Perrot, D. and Dollé, M. ACS Applied Polymer Materials 2021. Figure 1
Thèses sur le sujet "Polymer Electrolytes - Ion Dynamics"
1
Shen, Kuan-Hsuan. « Modeling ion conduction through salt-doped polymers : Morphology, ion solvation, and ion correlations ». The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595422569403378.
Texte intégral
2
Kidd, Bryce Edwin. « Multiscale Transport and Dynamics in Ion-Dense Organic Electrolytes and Copolymer Micelles ». Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/82525.
Texte intégralRésumé :
Understanding molecular and ion dynamics in soft materials used for fuel cell, battery, and drug delivery vehicle applications on multiple time and length scales provides critical information for the development of next generation materials. In this dissertation, new insights into transport and kinetic processes such as diffusion coefficients, translational activation energies (Ea), and rate constants for molecular exchange, as well as how these processes depend on material chemistry and morphology are shown. This dissertation also aims to serve as a guide for material scientists wanting to expand their research capabilities via nuclear magnetic resonance (NMR) techniques. By employing variable temperature pulsed-field-gradient (PFG) NMR diffusometry, which can probe molecular transport over nm – μm length scales, I first explore transport and morphology on a series of ion-conducting materials: an organic ionic plastic crystal, a proton-exchange membrane, and a polymer-gel electrolyte. These studies show the dependencies of small molecule and ion transport on modulations to material parameters, including thermal or magnetic treatment, water content, and/or crosslink density. I discuss the fundamental significance of the length scale over which translational Ea reports on these systems (~ 1 nm) and the resulting implications for using the Arrhenius equation parameters to understand and rationally design new ion-conductors. Next, I describe how NMR spectroscopy can be utilized to investigate the effect of loading a small molecule into the core of a spherical block copolymer micelle (to mimic, e.g., drug loading) on the hydrodynamic radius (rH) and polymer chain dynamics. In particular, I present spin-lattice relaxation (T1) results that directly measure single chain exchange rate kexch between micelles and diffusion results that inform on the unimer exchange mechanism. These convenient NMR methods thus offer an economical alternative (or complement) to time-resolved small angle neutron scattering (TR-SANS).Ph. D.
3
Karo, Jaanus. « The Rôle of Side-Chains in Polymer Electrolytes for Batteries and Fuel Cells ». Doctoral thesis, Uppsala universitet, Strukturkemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-100738.
Texte intégralRésumé :
The subject of this thesis relates to the design of new polymer electrolytes for battery and fuel cell applications. Classical Molecular Dynamics (MD) modelling studies are reported of the nano-structure and the local structure and dynamics for two types of polymer electrolyte host: poly(ethylene oxide) (PEO) for lithium batteries and perfluorosulfonic acid (PFSA) for polymer-based fuel cells. Both polymers have been modified by side-chain substitution, and the effect of this on charge-carrier transport has been investigated. The PEO system contains a 89-343 EO-unit backbone with 3-15 EO-unit side-chains, separated by 5-50 EO backbone units, for LiPF6 salt concentrations corresponding to Li:EO ratios of 1:10 and 1:30; the PFSA systems correspond to commercial Nafion®, Hyflon® (Dow®) and Aciplex® fuel-cell membranes, where the major differences again lie in the side-chain lengths. The PEO mobility is clearly enhanced by the introduction of side-chains, but is decreased on insertion of Li salts; mobilities differ by a factor of 2-3. At the higher Li concentration, many short side-chains (3-5 EO-units) give the highest ion mobility, while the mobility was greatest for side-chain lengths of 7-9 EO units at the lower concentration. A picture emerges of optimal Li+-ion mobility correlating with an optimal number of Li+ ions in the vicinity of mobile polymer segments, yet not involved in significant cross-linkages within the polymer host. Mobility in the PFSA-systems is promoted by higher water content. The influence of different side-chain lengths on local structure was minor, with Hyflon® displaying a somewhat lower degree of phase separation than Nafion®. Furthermore, the velocities of the water molecules and hydronium ions increase steadily from the polymer backbone/water interface towards the centre of the proton-conducting water channels. Because of its shorter side-chain length, the number of hydronium ions in the water channels is ~50% higher in Hyflon® than in Nafion® beyond the sulphonate end-groups; their hydronium-ion velocities are also ~10% higher. MD simulation has thus been shown to be a valuable tool to achieve better understanding of how to promote charge-carrier transport in polymer electrolyte hosts. Side-chains are shown to play a fundamental rôle in promoting local dynamics and influencing the nano-structure of these materials.
4
Shi, Jie. « Ion transport in polymer electrolytes ». Thesis, University of St Andrews, 1993. http://hdl.handle.net/10023/15522.
Texte intégralRésumé :
The ion-polymer and ion-ion interactions in polymer electrolytes based on high molecular weight, amorphous methoxy-linked PEO (PMEO) and lithium salts have been investigated by conductivity measurement, magic-angle spinning NMR (mas NMR) and pulsed field gradient NMR (pfgNMR) techniques. In the very dilute salt concentration region, ion pairing effects are dominant in these polymer electrolytes. Ion association is found to increase with temperature and salt concentration. Ion transport for these electrolytes is controlled both by segmental motion of the polymer and activation process, in which the former is important for the dilute concentration samples while the latter is important for the concentrated samples. The mass transport process in polymer electrolytes based on a zinc salt has been investigated by steady state dc polarisation and Hittorf techniques. Zinc ion constituents in these electrolytes are mobile with a limiting current fraction of about 0.2 at 80°C, and the transference number measured by the Hittorf method is less than 0.1. The main species in these electrolytes are proposed to be neutral mobile triples. The electrode-electrolyte interfaces in polymer electrolytes based on calcium and magnesium salts have been studied. Dc polarisation experiments for these polymer electrolytes were carried out using two electrode cells with the metal anode and mercury film amalgam cathode. The results of dc polarisation experiments suggest that calcium species are mobile in high molecular weight electrolytes, while magnesium species are immobile. The influence of the molecular weight of the polymer on the dynamics of cation constituents has been studied based on the experimental results of dc polarisation and pfg NMR, and on the theoretical analyses of the reptation theory and the Rouse model. It is found that the transport of the gravity centre of the polymer will influence the ion transport in polymer electrolytes based on PEO in a manner described by the Rouse model when the molecular weight of PEO is less than 3200.
5
Sorrie, Graham A. « Liquid polymer electrolytes ». Thesis, University of Aberdeen, 1987. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU499826.
Texte intégralRésumé :
This thesis is concerned with ion-ion and ion-polymer interactions over a wide concentration range in polymer electrolytes with a view to shedding new light on the mechanism of ion migration. Additionally, the electrochemical stability window of these electrolytes on platinum and vitreous carbon electrodes has been thoroughly investigated. The final part of this thesis is concerned with determining the feasibility of polymer electrolytes as electrolytes in a new type of energy storage device, a double layer capacitor which incorporates activated carbon cloth electrodes. Conductivities and viscosities of solutions of Li, Na and K thiocyanates in low-molecular-weight, non-crystallizable liquid copolymers of ethylene oxide (EO) and propylene oxide (PO) have been measured. The curves of molar conductance versus sqrt c show well-defined maxima and minima. The conductivity is independent of copolymer molecular-weight but is enhanced by raising the EO content of the copolymer. The results are interpreted in terms of a model for ion migration in which ion association and redissociation effects play an important role. It is proposed that the characteristic properties of liquid polymer electrolytes can only be satisfactorily explained if the current is largely anionic. The electrochemical stability window of these electrolytes on platinum is dominated by the presence of a water reduction peak starting at approximately -1.0V which limits the overall stability to approximately 2V. The onset of water reduction is displaced to more negative potentials (-3.0V), thus increasing the stability window, on vitreous carbon electrodes. The value of the double layer capacitance on vitreous carbon electrodes (15-30muF cm-2) agrees well with published data. The double layer capacitance of activated carbon cloth electrodes is lower than anticipated. The importance of faradaic charging and discharging currents to the successful operation of double layer capacitors is indicated but no problems relating to the specific use of polymer electrolytes in such devices were found.
6
McHattie, Gillian S. « Ion transport in liquid crystalline polymer electrolytes ». Thesis, University of Aberdeen, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324432.
Texte intégralRésumé :
A systematic study of structure-property relations has been carried out on a range of polymers, both with and without mesogenic moieties. These materials have been characterised using various thermal techniques, including DSC and DMTA. These polymers have been complexed with LiClO4 and the effects of the salt on thermal characteristics have been investigated. In addition, AC impedance spectroscopy has been employed to determine the temperature dependence of the conductivity of these complexes. Results suggest that polymers with mesogenic side groups have the potential to exhibit a conduction mechanism which is independent of both the glass transition temperature of the complex as determined by DSC and the corresponding structural relaxation detected using DMTA. It is found that the glass transition temperature of these materials is determined primarily by the side groups, and not by the polymer backbone. A model is thereby proposed in which ionic motion is decoupled from Tg, but still dependent on the local viscosity of the ionic environment. Appreciable conductivity is therefore observed below the glass transition temperature of the complex, thus resulting in dimensionally stable polymeric complexes with possible applications as solid state electrolytes in batteries.
7
Lacey, Matthew James. « Electrodeposited polymer electrolytes for 3D Li-ion microbatteries ». Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/348605/.
Texte intégralRésumé :
The electropolymerisation of vinyl monomers has been investigated as a route to the conformal deposition of thin polymer electrolyte films on porous electrode surfaces, for application in 3D Li-ion microbatteries. The deposition of poly(acrylonitrile) and poly(poly(ethylene glycol) diacrylate) has been monitored using cyclic voltammetry and an electrochemical quartz crystal microbalance (EQCM). It was determined that the polymerisation reaction may be initiated either by direct reduction of the monomer or via a separate reactive intermediate such as the superoxide anion. Furthermore, it was established that film thickness was easily controlled under cyclic voltammetry conditions, for example by varying the number of cycles. However, the choice of solvent and electrode surface was found to be of critical importance. This electropolymerisation technique was adapted to achieve the single step electrodeposition of a gel polymer electrolyte based on poly(ethylene glycol) diacrylate (PEGDA). Modification of the polymer to improve the mechanical properties and ionic conductivity was achieved by the incorporation of silica nanoparticles and plasticising monoacrylates into the polymer matrix. Through these modification procedures a PEGDA-based electrolyte was prepared with an ionic conductivity of the order of 10−4 S cm−1 and demonstrated, for the first time, sufficient mechanical strength to be used as the separator in spring-pressured planar half- and full cell configurations. The conformal nature of the deposit was assessed by scanning electron microscopy (SEM) and it was found that a uniform film of thickness as low as 2 μm was easily achievable. An initial attempt at a full 3D Li-ion microbattery cell based on a carbon foam substrate using composite electrode materials was made. The electrodeposited polymer electrolyte showed good electronic isolation and the cell showed limited cycling ability. The internal structure of the 3D cell was investigated by SEM and x-ray computed tomography.
8
Chen, Songela Wenqian. « Modeling ion mobility in solid-state polymer electrolytes ». Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122534.
Texte intégralRésumé :
Thesis: S.B., Massachusetts Institute of Technology, Department of Chemistry, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 31-32).
We introduce a course-grained model of ion diffusion in a solid-state polymer electrolyte. Among many tunable parameters, we investigate the effect of ion concentration, ion-polymer attraction, and polymer disorder on cation diffusion. For the conditions tested, we find that ion concentration has little effect on diffusion. Polymer disorder creates local variation in behavior, which we call "trapping" (low diffusion) and "free diffusing" (high diffusion) regions. Changing ion-polymer attraction modulates the relative importance of trapping and free diffusing behavior. Using this model, we can continue to investigate how a number of factors affect cation diffusion both mechanistically and numerically, with the end goal of enabling rapid computational material design.
by Songela Wenqian Chen.
S.B.
S.B. Massachusetts Institute of Technology, Department of Chemistry
9
Maranski, Krzysztof Jerzy. « Polymer electrolytes : synthesis and characterisation ». Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3411.
Texte intégralRésumé :
Crystalline polymer/salt complexes can conduct, in contrast to the view held for 30 years. The alpha-phase of the crystalline poly(ethylene oxide)₆:LiPF₆ is composed of tunnels formed from pairs of (CH₂-CH₂-O)ₓ chains, within which the Li⁺ ions reside and along which the latter migrate.¹ When a polydispersed polymer is used, the tunnels are composed of 2 strands, each built from a string of PEO chains of varying length. It has been suggested that the number and the arrangement of the chain ends within the tunnels affects the ionic conductivity.² Using polymers with uniform chain length is important if we are to understand the conduction mechanism since monodispersity results in the chain ends occurring at regular distances along the tunnels and imposes a coincidence of the chain ends between the two strands.² Since each Li⁺ is coordinated by 6 ether oxygens (3 oxygens from each of the two polymeric strands forming a tunnel), monodispersed PEOs with the number of ether oxygen being a multiple of 3 (NO = 3n) can form either “all-ideal” or “all-broken” coordination environments at the end of each tunnel, while for both NO = 3n-1 and NO = 3n+1 complexes, both “ideal” and “broken” coordinations must occur throughout the structure. A synthetic procedure has been developed and a series of 6 consecutive (increment of EO unit) monodispersed molecular weight PEOs have been synthesised. The synthesis involves one end protection of a high purity glycol, functionalisation of the other end, ether coupling reaction (Williamson's type ether synthesis³), deprotection and reiteration of ether coupling. The parameters of the process and purification methods have been strictly controlled to ensure unprecedented level of monodispersity for all synthesised samples. Thus obtained high purity polymers have been used to study the influence of the individual chain length on the structure and conductivity of the crystalline complexes with LiPF₆. The results support the previously suggested model of the chain-ends arrangement in the crystalline complexes prepared with monodispersed PEO² over a range of consecutive chain lengths. The synthesised complexes constitute a series of test samples for establishing detailed mechanism of ionic conductivity. Such series of monodispersed crystalline complexes have been studied and characterised here (PXRD, DSC, AC impedance) for the first time. References: 1. G. S. MacGlashan, Y. G. Andreev, P. G. Bruce, Structure of the polymer electrolyte poly(ethylene oxide)₆:LiAsF₆. Nature, 1999, 398(6730): p. 792-794. 2. E. Staunton, Y. G. Andreev, P. G. Bruce, Factors influencing the conductivity of crystalline polymer electrolytes. Faraday Discussions, 2007, 134: p. 143-156. 3. A. Williamson, Theory of Aetherification. Philosophical Magazine, 1850, 37: p. 350-356.
10
Hekselman, Aleksandra K. « Crystalline polymer and 3D ceramic-polymer electrolytes for Li-ion batteries ». Thesis, University of St Andrews, 2014. http://hdl.handle.net/10023/11950.
Texte intégralRésumé :
The research work presented in this thesis comprises a detailed investigation of conductivity mechanism in crystalline polymer electrolytes and development of a new class of ceramic-polymer composite electrolytes for Li-ion batteries. Firstly, a robust methodology for the synthesis of monodispersed poly(ethylene oxides) has been established and a series of dimethyl-protected homologues with 13, 15, 17, 28, 29, 30 ethylene oxide repeat units was prepared. The approach is based on reiterative cycles of chain extension and deprotection, followed by end-capping of the oligomeric chain ends with methyl groups. The poly(ethylene oxide) homologues show a superior level of monodispersity to previous work and were subsequently used to prepare crystalline PEO6:LiPF6 polymer electrolytes. A correlation between the number of ether oxygens in the polymer chain and the ionic conductivity of crystalline polymer electrolytes has been established. The structure and dynamics of the monodispersed complexes were studied using solid-state NMR spectroscopy for the first time. The results are in agreement with the proposed mechanism of ionic conductivity in crystalline polymer electrolytes. A new class of composite solid electrolytes for all-solid-state batteries with a lithium metal anode is reported. The composite material consists of a 3D interpenetrating network of a ceramic electrolyte, Li₁.₄Al₀.₄Ge₁.₆(PO₄)₃, and an inert polymer (polypropylene), providing continuous pathways for the ionic transport and excellent mechanical properties. 3D connectivity of this novel composite was confirmed using X-ray microtomography and AC impedance spectroscopy.
Livres sur le sujet "Polymer Electrolytes - Ion Dynamics"
1
Writer, Beta. Lithium-Ion Batteries : A Machine-Generated Summary of Current Research. Springer, 2019.
Trouver le texte intégralChapitres de livres sur le sujet "Polymer Electrolytes - Ion Dynamics"
1
Arya, Anil, Annu Sharma, A. L. Sharma et Vijay Kumar. « Ion Dynamics and Dielectric Relaxation in Polymer Composites ». Dans Polymer Electrolytes and their Composites for Energy Storage/Conversion Devices, 67–97. New York : CRC Press, 2022. http://dx.doi.org/10.1201/9781003208662-4.
Texte intégral
2
Scrosati, Bruno. « Lithium Polymer Electrolytes ». Dans Advances in Lithium-Ion Batteries, 251–66. Boston, MA : Springer US, 2002. http://dx.doi.org/10.1007/0-306-47508-1_9.
Texte intégral
3
Maranas, Janna K. « Solid Polymer Electrolytes ». Dans Dynamics of Soft Matter, 123–43. New York, NY : Springer US, 2011. http://dx.doi.org/10.1007/978-1-4614-0727-0_5.
Texte intégral
4
Kim, Dong-Won. « CHAPTER 5. Gel Polymer Electrolytes ». Dans Future Lithium-ion Batteries, 102–29. Cambridge : Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/9781788016124-00102.
Texte intégral
5
Albinsson, I., et B. E. Mellander. « Electrical Relaxation in Polymer Electrolytes ». Dans Fast Ion Transport in Solids, 347–52. Dordrecht : Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1916-0_20.
Texte intégral
6
Vondrák, J., M. Sedlaríková, J. Reiter et D. Kašpar. « PMMA Based Gel Polymer Electrolytes ». Dans Materials for Lithium-Ion Batteries, 623–25. Dordrecht : Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-011-4333-2_57.
Texte intégral
7
Bruce, Peter G. « Polymer Electrolytes and Intercalation Electrodes : Fundamentals and Applications ». Dans Fast Ion Transport in Solids, 87–107. Dordrecht : Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1916-0_5.
Texte intégral
8
Nishi, Yoshio. « Lithium-Ion Secondary Batteries with Gelled Polymer Electrolytes ». Dans Advances in Lithium-Ion Batteries, 233–49. Boston, MA : Springer US, 2002. http://dx.doi.org/10.1007/0-306-47508-1_8.
Texte intégral
9
Jishnu, N. S., M. A. Krishnan, Akhila Das, Neethu T. M. Balakrishnan, Jou-Hyeon Ahn, Fatima M. J. Jabeen et Prasanth Raghavan. « Polymer Clay Nanocomposite Electrolytes for Lithium-Ion Batteries ». Dans Polymer Electrolytes for Energy Storage Devices, 187–217. First edition | Boca Raton : CRC Press, 2021. : CRC Press, 2021. http://dx.doi.org/10.1201/9781003144793-9.
Texte intégral
10
Sarma, Prasad V., Jayesh Cherusseri et Sreekanth J. Varma. « Polymer Nanocomposite-Based Solid Electrolytes for Lithium-Ion Batteries ». Dans Polymer Electrolytes for Energy Storage Devices, 81–110. First edition | Boca Raton : CRC Press, 2021. : CRC Press, 2021. http://dx.doi.org/10.1201/9781003144793-4.
Texte intégralActes de conférences sur le sujet "Polymer Electrolytes - Ion Dynamics"
1
Tokumasu, Takashi. « Proton Transfer in Polymer Electrolyte Membrane by Molecular Dynamics Method ». Dans ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology collocated with ASME 2011 5th International Conference on Energy Sustainability. ASMEDC, 2011. http://dx.doi.org/10.1115/fuelcell2011-54963.
Texte intégralRésumé :
This paper describes characteristics of proton transfer in polymer electrolyte membrane by Molecular Dynamics (MD) simulation. Nafion was used as a membrane. Grotthus mechanism as well as Vehicle mechanism was considered in the simulation. To treat Grotthus mechanism, Empirical Valence Bond (EVB) method was used. The parameters or functions of the interaction potential of EVB method were determined so that potential energy barrier of proton hopping obtained by EVB method is consistent with that obtained by Density Functional Theory (DFT) and adjusted so that the diffusion coefficient of hydronium ion in water obtained by MD simulation is consistent with that of experimental results. After annealing the system, radial distribution function or mean square displacements of hydronium ion and water, which correspond to diffusivity of each compound, was obtained. These results show the nanoscale characteristics of proton transfer in polymer electrolyte membrane.
2
Tokumasu, Takashi, et Taiki Yoshida. « A Molecular Dynamics Study for Diffusivity of Proton in Polymer Electrolyte Membrane ». Dans ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44195.
Texte intégralRésumé :
This paper describes characteristics of proton transfer in polymer electrolyte membrane by Molecular Dynamics (MD) simulation. Nafion was used as a membrane. Grotthus mechanism as well as Vehicle mechanism was considered in the simulation. To treat Grotthus mechanism, Empirical Valence Bond (EVB) method was used. The parameters or functions of the interaction potential of EVB method were determined so that potential energy barrier of proton hopping obtained by EVB method is consistent with that obtained by Density Functional Theory (DFT) and adjusted so that the diffusion coefficient of hydronium ion in water obtained by MD simulation is consistent with that of experimental results. After annealing the system, radial distribution function or mean square displacements of hydronium ion and water, which correspond to diffusivity of each compound, was obtained. These results show the nanoscale characteristics of proton transfer in polymer electrolyte membrane.
3
Zhou, Xiangyang. « Atomistic Modeling of Conduction and Transport Processes in Micro-Porous Electrodes Containing Nafion Electrolytes ». Dans ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18116.
Texte intégralRésumé :
Atomistic modeling and/or experimental methods were conducted to study transport processes in the porous electrodes of polymer electrolyte fuel cells (PEFCs) and of mediator enhanced polymer electrolyte supercapacitors (MEPESCs). The simulations show that vibrations of the Pt nanocrystallines on rhe carbon supports significantly impacts diffusion in the Nafion electrolyte clusters between the carbon supports and enhances the diffusivity of hydrogen, oxygen, methanol, water, and hydronium up to 8 times the nominal value. Charging the carbon support alters the diffusivities. It was visualized that charging of Pt nanocrystallines resulted in disintegration of the Pt catalysts leading to a reduction in catalytic activity of the catalyst layer. Re-precipitation and re-crystallization of the Pt under a full discharging condition can also be visualized using the molecular dynamics (MD) modeling method. MD simulations also indicate that the mobility of the iodine mediators is at least 10 times greater than other small ions in the Nafion electrolyte. The degradation of the MEPESC is dominated by the crossover of I− ions but not I2 in Nafion.
4
Mabuchi, Takuya, et Takashi Tokumasu. « Molecular Dynamics Study of Proton and Water Transport in Nafion Membrane ». Dans ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icnmm2013-73084.
Texte intégralRésumé :
Polymer electrolyte fuel cells (PEFCs) are highly expected as a next-generation power supply system due to the purity of its exhaust gas, its high power density and high efficiency. The polymer electrolyte membrane is a critical component for the performance of the PEFCs and it is important to understand the nanostructure in the membrane to enhance proton transport. We have performed an atomistic analysis of the vehicular transport of hydronium ions and water molecules in the nanostructure of hydrated Nafion membrane by systematically changing the hydration level which provides insights into a connection between the nanoscopic and mesoscopic structure of ion clusters and the dynamics of hydronium ions and water molecules in the hydrated Nafion membrane. In this study, classical molecular dynamics simulations are implemented using a model of Nafion membrane which is based on DREIDING force field and newly modified and validated by comparing the density, water diffusivity, and Nafion morphology with experimental data. The simulated final density after the annealing procedure agrees with experiment within 1.3 % for various water contents and the trends that density decreases with increasing hydration level are reproduced. In addition to determination of diffusion coefficients of solvent molecules as a function of hydration level (from λ = 1 up to λ = 18), we have also calculated radial distribution functions and static structure factors not only to clarify the structure of water molecules and hydronium ions around the first solvation shell of sulfonate groups but also to validate the mesoscopic periodic structure among water clusters. The diffusion coefficient of water molecules increases with increasing hydration level and is found to be in good agreement with experimental data. The diffusion coefficient of hydronium ions has showed that general trends in the experimental data are reproduced by the simulations although the classical models have the limitation of probing hydronium dynamics. The static structure factors of liquid molecules at low wave length provide insights into the periodic structure of the inter-water clusters. These results are consistent with the Gebel’s model based on small-angle X-ray scattering that considers the dry membrane to be made of isolated spherical ionic clusters of radius ∼7.5 Å that swell with increasing hydration.
5
Venugopal, Vinithra, Hao Zhang et Vishnu-Baba Sundaresan. « A Chemo-Mechanical Constitutive Model for Conducting Polymers ». Dans ASME 2013 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/smasis2013-3218.
Texte intégralRésumé :
Conducting polymers undergo volumetric expansion through redox-mediated ion exchange with its electrolytic environment. The ion transport processes resulting from an applied electrical field controls the conformational relaxation in conducting polymer and regulates the generated stress and strain. In the last two decades, significant contributions from various groups have resulted in methods to fabricate, model and characterize the mechanical response of conducting polymer actuators in bending mode. An alternating electrical field applied to the polymer electrolyte interface produces the mechanical response in the polymer. The electrical energy applied to the polymer is used by the electrochemical reaction in the polymer backbone, for ion transport at the electrolyte-polymer interface and for conformational changes to the polymer. Due to the advances in polymer synthesis, there are multitudes of polymer-dopant combinations used to design an actuator. Over the last decade, polypyrrole (PPy) has evolved to be the most common conducting polymer actuator. Thin sheets of polymer are electrodeposited on to a substrate, doped with dodecylbezenesulfonate (DBS-) and microfabricated into a hermetic, air operated cantilever actuator. The electrical energy applied across the thickness of the polymer is expended by the electrochemical interactions at the polymer-electrolyte interface, ion transport and electrostatic interactions of the backbone. The widely adopted model for designing actuators is the electrochemically stimulated conformational relaxation (ESCR) model. Despite these advances, there have been very few investigations into the development of a constitutive model for conducting polymers that represent the input-output relation for chemoelectromechanical energy conversion. On one hand, dynamic models of conducting polymers use multiphysics-based non-linear models that are computationally intensive and not scalable for complicated geometries. On the other, empirical models that represent the chemomechanical coupling in conducting polymers present an over-simplified approach and lack the scientific rigor in predicting the mechanical response. In order to address these limitations and to develop a constitutive model for conducting polymers, its coupled chemomechanical response and material degradation with time, we have developed a constitutive model for polypyrrole-based conducting polymer actuator. The constitutive model is applied to a micron-scale conducting polymer actuator and coupling coefficients are expressed using a mechanistic representation of coupling in polypyrrole (dodecylbenzenesulfonate) [PPy(DBS)].
6
Nagpure, Tushar, et Zheng Chen. « Modeling of Ionic Polymer-Metal Composite-Enabled Hydrogen Gas Production ». Dans ASME 2015 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/dscc2015-9922.
Texte intégralRésumé :
Hydrogen extraction using water electrolysis, and microbial biomass conversion are clean and minimum-emission option for renewable energy storage applications. Ionic polymer-metal composite (IPMC) is a category of electro-active polymers that exhibits the property of ion migration under the application of external voltage. This property of IPMC is useful in electrolysis of water (H2O) and produce hydrogen (H2) and oxygen (O2) gases. This paper discusses the electrochemical fundamentals of electrolysis, which provides a linear relationship between the flow rate of hydrogen from electrolysis and the source current. An IPMC electrolyzer circuit model is developed to capture the electrical characteristic of IPMC. The model incorporates nonlinear capacitance, pseudo-capacitance, and a nonlinear resistance defined with a polynomial function. A state-space equation is then obtained to simulate the proposed circuit model for electrolysis. Experimental result shows that the flow-rate of hydrogen production is proportional to the system current and the proposed model validates the step-response of the system. The model prediction error is less than 4.5647%.
7
Sakai, Kiminori, et Takashi Tokumasu. « Molecular Dynamics Study of Oxygen Permeation Through the Ionomer of PEFC Catalyst Layer ». Dans ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-36020.
Texte intégralRésumé :
Polymer electrolyte membrane fuel cell (PEFC) is focused worldwide as the energy conversion device of next generation. In the PEFC cathode catalyst layer, an ionomer with which the catalyst is covered is very important on the point of transferring protons to the catalytic surface on the cathode side. On the other hand, it is said that an ionomer interferes with oxygen permeation to the catalytic surface. The mechanism of oxygen permeation through an ionomer was not analyzed in detail because it is too small to research by experiment. Moreover molecular dynamics simulation of the catalyst layer and oxygen permeability has not yet studied. In this research, we constructed the system including nafion, water, oxonium ion, platinum layers by using molecular dynamics study, and studied about the effect of the water content of the ionomer on the structure of the ionomer and permeability of the oxygen molecule. As the results, a lot of oxygen molecules permeated through a dried ionomer and reached to the catalytic surface but there were few oxygen molecules that permeated through a hydrated ionomer and reached there. In addition, it is found that the shape of the ionomer in the case of water content rate γ = 3, 7, 11 changed.
8
Sadiq, M., Anil Arya et Ashish kumar Yadav Manoj K Singh. « Scheme of Polymer-Ion-clay Interaction and Ion-Ion Interaction In Polymer Nanocomposite Electrolytes Films ». Dans Proceedings of the International Conference on Nanotechnology for Better Living. Singapore : Research Publishing Services, 2016. http://dx.doi.org/10.3850/978-981-09-7519-7nbl16-rps-171.
Texte intégral
9
Ogata, N., K. Sanui, M. Rikukawa, S. Yamada et M. Watanabe. « Super ion conducting polymers for solid polymer electrolytes ». Dans International Conference on Science and Technology of Synthetic Metals. IEEE, 1994. http://dx.doi.org/10.1109/stsm.1994.835672.
Texte intégral
10
Zhang, Ruisi, Niloofar Hashemi, Maziar Ashuri et Reza Montazami. « Advanced Gel Polymer Electrolyte for Lithium-Ion Polymer Batteries ». Dans ASME 2013 7th International Conference on Energy Sustainability collocated with the ASME 2013 Heat Transfer Summer Conference and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/es2013-18386.
Texte intégralRésumé :
We report improved performance of Li-ion polymer batteries through advanced gel polymer electrolytes (GPEs). Compared to solid and liquid electrolytes, GPEs are advantageous as they can be fabricated in different shapes and geometries; also ionic properties are significantly superior to that of solid and liquid electrolytes. We have synthetized GPE in form of membranes by trapping ethylene carbonate and propylene carbonate in a composite of polyvinylidene fluoride and N-methylpyrrolidinore. By applying phase-transfer method, we synthetized membranes with micro-pores, which led to higher ionic conductivity. The proposed membrane is to be modified further to have higher capacity, stronger mechanical properties, and lower internal resistance. In order to meet those requirements, we have doped the samples with gold nanoparticles (AuNPs) to form nanoparticle-polymer composites with tunable porosity and conductivity. Membranes doped with nanoparticles are expected to have higher porosity, which leads to higher ion mobility; and improved electrical conductivity. Four-point-probe measurement technique was used to measure the sheet resistance of the membranes. Morphology of the membranes was studied using electron and optical microscopies. Cyclic voltammetry and potentiostatic impedance spectroscopy were performed to characterize electrochemical behavior of the samples as a function of weight percentage of embedded AuNPs.
Rapports d'organisations sur le sujet "Polymer Electrolytes - Ion Dynamics"
1
Arnold, John. Supramolecular Engineering of New Lithium Ion Conducting Polymer Electrolytes. Fort Belvoir, VA : Defense Technical Information Center, janvier 2001. http://dx.doi.org/10.21236/ada431777.
Texte intégral
2
Greenbaum, Steven G. Lithium Ion Transport Across and Between Phase Boundaries in Heterogeneous Polymer Electrolytes, Based on PVdF. Fort Belvoir, VA : Defense Technical Information Center, février 1998. http://dx.doi.org/10.21236/ada344887.
Texte intégral