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1
Van, Heerden D. P. "Degradation of the beta-alumina electrolyte in a zebra cell". Master's thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/17666.
Testo completoAbstract (sommario):
Bibliography: pages 103-106.Beta-alumina solid electrolytes studied were subjected to charge and discharge cycles in a secondary, high energy density Na/beta-alumina/NaAlCl₄/FeCl₂ cell (known as the Zebra cell) at 250⁰ C. These electrolytes were studied by means of optical microscopy, as well as SEM and EDS analyses to est ablish possible failure modes. After cycling little discolouration, or impurity pickup was found to have occurred in the electrolyte. The forms of degradation of the beta-alumina electrolyte identified appeared to be a result of inherent flaws in the beta-alumina electrolyte tube, problems due to protracted storage of the tubes, or an apparent interfacial film on the cathode/electrolyte interface. A lead wetting agent was used in the cells to enhance the wetting of the beta-alumina electrolyte by the liquid Na. A study of the coating after cycling of the cell showed that the coating was adherent irrespective of the number of cycles completed. The coating did not appear to influence cracking of the electrolyte during cycling. Cracking of the beta-alumina electrolyte was found to have initiated from the Na/electrolyte interface. No evidence of crack initiation nor internal damage was found on the cathode/electrolyte interface. The cracks through the beta-alumina electrolyte wall were found to have sealed by the formation of a plug consisting largely of Na and Cl. On the basis of EDS analyses of the fracture surface of the sealed crack possible sealing mechanisms are proposed.
2
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.
Testo completoAbstract (sommario):
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.
3
Stuart, Paul Anthony. "The synthesis and evaluation of proton conducting electrolytes for high temperature steam electrolysers". Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/5571.
Testo completoAbstract (sommario):
Proton conducting ceramics based on acceptor doped perovskites are the subject of investigation as candidate electrolyte materials for Solid Oxide Electrolyser Cells (SOECs). Specifically, BaCe0.9Y0.1O3-[delta](BCY10) and BaZr0.9Y0.1O3-[delta](BZY10) were investigated. Samples with greater than 95% of the maximum theoretical density were successfully prepared using a BCY10 commercial powder. It was found that when small additions of ZnO were added to a BZY10 commercial powder, a density of greater than 95% of the theoretical maximum was achievable whereas without ZnO addition, the maximum achievable density was 85%. BCY10 was found to have a total conductivity approximately one order of magnitude greater than Zndoped BZY10 over the entire temperature range studied. Spray pyrolysis and sol-gel methods were used successfully to prepare single phase pure BZY10 powders. The sintering behaviours of the powders produced by spray pyrolysis were found to alter significantly with changes in powder processing parameters. BCY10 and Zn-doped BZY10 cells were tested in electrolysis and fuel cell modes and the effects of varying operating conditions on cell performances were studied. At 750oC, the Area Specific Resistances (ASR) of a BCY10 cell in electrolysis mode was found to be lower when the anode compartment was humidified to [approximately equal]83% than to[approximately equal]3%. Below this temperature, ASR values were greater when using increased humidity levels. It was concluded that a degree of oxide ion conduction may be beneficial to the operation of proton conducting electrolysers. Post-test, BCY10 cell cross-sections were imaged using scanning electron microscopy and analysed using Energy Dispersive X-ray (EDX) spectroscopy. Significant erosion of grain boundaries regions close the electrode-electrolyte interfaces was observed and EDX spectroscopy results suggested the formation of a secondary phase in these regions, possibly Y:CeO2. Had testing continued over an extended period of time it is probable that BCY10 cells would have undergone mechanical failure.
4
McLennaghan, A. W. "Linear segmented polyurethane electrolytes". Thesis, University of Strathclyde, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382418.
Testo completo
5
Klein, Jeffrey M. "Electrode-Electrolyte and Solvent-Solute Interfaces of Concentrated Electrolytes: Ionic Liquids and Deep Eutectic Solvents". Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1620213066452923.
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6
Wauters, Cary N. "Electrolytic membrane recovery of bromine from waste gas-phase hydrogen bromide streams using a molten salt electrolyte". Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/10131.
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7
Zhao, Xin. "Electropolishing of Niobium in Sulfuric Acid-Methanol Electrolytes: Development of Hydrofluoric Acid-Free Electrolytes". Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/28507.
Testo completoAbstract (sommario):
Niobium (Nb) has the highest superconducting transition temperature (9.2 K) of the pure metals, which makes it the most used material for the construction of superconducting radio frequency (SRF) accelerators. The performance of the accelerator is critically dependent upon the quality of Nb surface. Electropolishing (EP) in hydrofluoric acid (HF)-containing electrolytes is the currently accepted treatment process. The presence of HF is necessary for the removal of the passive oxide surface film formed in aqueous electrolytes. But HF is hazardous and must be contained without human exposure and eliminated in an environmentally appropriate manner.
In the present dissertation project, HF-Free EP of Nb was performed in sulfuric acid-methanol electrolytes. Sulfuric concentrations of 0.1 M, 0.5 M, 1 M, 2 M, and 3 M were used. Cyclic voltammetry and potential hold experiments were performed in cells of both two-electrode and three-electrode setups to evaluate the electrochemical process. The influence of electrolyte concentration, temperature, and EP duration was investigated. At room temperature, both the corrosion rate and the surface quality obtained were comparable to those currently obtained with HF-based processing. With decreasing temperature, the mean current level decreased and the surface quality improved substantially. For a desired average material removal of 100 μM, nanometer scale surface roughness was obtained under multiple conditions.
Mechanism of EP was also investigated by electrochemical impedance spectroscopy (EIS). The EIS diagram indicates the presence of a compact film during EP at mass transport controlled limiting current and a film-free surface during EP at ohmic controlled current. Transfer from a film-free surface to an anodic film precipitation with decreasing temperature was also observed. Microsmoothing is only achieved under mass transport control. Nb⁵⁺ ions are determined to be the mass transport limiting species.Ph. D.
8
Schlindwein, Walkiria Santos. "Conducting polymers and polymer electrolytes". Thesis, University of Leicester, 1990. http://hdl.handle.net/2381/33889.
Testo completoAbstract (sommario):
Polymers are mostly used as insulator materials. Since the late sixties, two new classes of polymeric materials possessing either ionic or electronic conductivities have been extensively studied. The work carried out in this thesis concerns of the study of polymer electrolytes based on poly(ethylene oxide) (PEO) complexed with divalent salts (ionic conductors) and polypyrroles (PPy) electrochemically and chemically prepared (electronic conductors). Different techniques were used to study their properties including Differential Scanning Calorimetry (DSC), Variable Temperature Polarising Microscopy (VTPM), Extended X-ray Absorption Fine Structure (EXAFS), a.c. Impedance, Cyclic Voltammetry, and Fourier Transform Infra-Red Spectroscopy (FTIR). Water-cast films of PEOn:ZnX2 (X = C1, Br, I) were prepared at a range of stoichiometries. The effects of either residual presence of water or thermal treatment related to the formation of high melting crystalline materials were investigated. The morphology of the zinc halides films differs from similar films cast from acetonitrile/methanol mixtures. The presence of high melting crystalline material in the water cast samples is influenced mostly by the concentration, type of anion and drying procedure applied to the samples. The high melting crystalline materials in the zinc samples are more affected by the drying regime. In some cases, solvent effects can be removed by using a high temperature (e.g. 180°C) drying regime. The presence of water normally depresses the melting temperature of the crystalline structures. Films of PEOn.:CaBr2 and PEOn:NiBr2 cast from water were also examined. The high melting crystalline materials in the calcium samples are more affected by the presence of water. The nickel samples are highly crystalline and the presence of high melting material does not seem to be influenced by either the presence of solvent or the drying procedure. EXAFS was used as a suitable technique to probe the local structure surrounding the cation. The results of the zinc halide samples gave some indication of the interionic and polymer-cation interactions. It was demonstrated that the halogen provides the most substantial contribution for the total EXAFS spectrum and the oxygen contribution is much less significant, except in the case of PEOn:ZnC12 samples. This could be due to the size of the nearest neighbour atoms and/or to the interaction polymer-cation. The presence of neutral "ion pairing" is suggested for the PEOn:ZnBr2 samples. The EXAFS results for the samples containing NiBr2 indicated a strong interaction between polymer-salt and the local structure was dependent on concentration, unlike the zinc samples. The polymerisation of pyrrole was investigated by using chemical and electrochemical oxidation routes. The structural characterisation of the compounds obtained was limited by their insolubility. The electrochemically prepared samples presented higher conductivity than the ones which were chemically prepared. The EXAFS results at the Fe K-edge of the PPyFeCl4 sample, which was prepared by direct chemical oxidation, suggested that the iron is coordinated to oxygens at a distance 1.97 A, chlorines at 3.08 A and perhaps nitrogens at 3.72 A. The iron local structure of the composite PVA/PPy doped with FeCl3 was different from the PPyFeCl4 sample. The iron in the composite sample was coordinated to oxygens at 1.98 A and chlorines at 2.18 A. Alternatively, the presence of a distorted FeCl4- is considered.
9
Edwards, William. "Structural Dynamics in Novel Electrolytes". Thesis, University of Kent, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.499827.
Testo completo
10
Worboys, M. R. "Ionic transport in polyether electrolytes". Thesis, University of Kent, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353186.
Testo completo
11
Clarke, M. D. "Electrochemical studies on polymeric electrolytes". Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373076.
Testo completo
12
Ismail, Iqbal M. I. "Electrochemical studies of polymer electrolytes". Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242319.
Testo completo
13
Mills, Glen E. "Computer modelling of polymer electrolytes". Thesis, Keele University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242281.
Testo completo
14
Chae, Jung Hoon. "Supercapacitors with neutral aqueous electrolytes". Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/30936/.
Testo completoAbstract (sommario):
Fossil fuels, which are the main energy sources of the current world, are running low and alternative ways of generating and storing different types of energies are becoming daunting missions. Renewable energy is very attractive because the source of the energy is often free and also environmentally friendly. The key issue to utilise the renewable energies in sustainable manner is how effectively store the energies and provide them on demand. Therefore, the significance of the energy storage devices has been widely recognised in recent time. Electrochemical capacitors (ECs), which are also commonly known as supercapacitors, are a type of the energy storage devices and the ECs are widely used as a back-up power boosting device to the batteries. Due to EC's low energy characteristics (typically, lower than 5 Wh/kg), their applications are limited. Therefore, main aim of this study is to enhance the energy characteristics of the ECs. In particular, aqueous ECs were examined due to a number of advantages offered by the water-based system. It was found that neutral aqueous electrolytes can expand the operating voltage close to 2 V (aqueous ECs commonly operate within 1 V) with advanced designs and hence result in remarkably higher energy. Moreover, the optimum condition of the neutral aqueous electrolytes was investigated by examining the effect of ion size, concentration and temperature. One of the main disadvantages of using the aqueous electrolytes in low temperatures was successfully resolved by using concentrated electrolytes (freezing point depressed up to -20°C). Mn02 with carbon materials were also used to construct asymmetrical ECs. The highest specific energy (Wh/kg) of the neutral aqueous ECs was achieved at 20 Wh/kg using unequal electrode design. This result is very much comparable to the Pb-acid battery. Based on the obtained data, larger scale (thicker and bigger electrode films) of the prototype ECs were constructed and their results correspond well with the results obtained from the smaller ECs. The data of the neutral aqueous ECs, which is contained in this thesis, suggest that the water-based ECs have a remarkable market potential.
15
Maranski, Krzysztof Jerzy. "Polymer electrolytes : synthesis and characterisation". Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3411.
Testo completoAbstract (sommario):
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.
16
Mehta, Mary Anne. "Multivalent ions in polymer electrolytes". Thesis, University of St Andrews, 1993. http://hdl.handle.net/10023/15517.
Testo completoAbstract (sommario):
The electrochemical, thermal and structural properties of polyethylene oxide (PEO) based polymer electrolytes containing multivalent ions were investigated. The phase diagram for the PEO:Ca(CF3SO3)2 system was determined by x-ray diffraction and differential scanning calorimetry techniques. Precipitation of the salt from the system at high temperatures was directly observed by variable temperature x- ray diffraction. This was ascribed to a negative entropy of dissolution of the salt in the polymer. A new crystalline complex PEO6Ca(CF3SO3)2, which exhibits a phase transition between two polymorphic forms was observed. The temperature dependence of ionic conductivity was related to the phase diagram. Redox behaviour of the PEO:Nil2 system was probed. Motion of the Ni(II) species through the system was extremely slow as evidenced by the low effective diffusion coefficient (1.82 x 10 11 cm 2s−1) and cationic current fraction (F+ < 0.1). Deposition of nickel from the polymer was characterised by instantaneous nucleation followed by three dimensional diffusion controlled growth. Investigation of the redox behaviour of the PE0:Eu(CF3SO3)3 system indicated that reduction of Eu3+ followed an ec mechanism. Evidence was obtained for extremely slow diffusion of Eu3+ containing species (D[sub]eff ~ 3.66 x 10 −16cm2s−1) through the system and slow kinetics of electron transfer. Thermal studies of the PEO:Co(SCN)2 system indicated that the glass transition temperature (Tg) was grossly elevated by the presence of Co(SCN)2 in the polymer. The absence of a crystalline PEO:Co(SCN)2 complex was ascribed to the high Tg which leads to slow crystallisation kinetics. UV-visible spectra indicated that the Co2+ ion was tetrahedrally coordinated in the system at low salt concentrations. The structure of the PEO3NaClO4 crystalline complex was reported as a subsidiary study.
17
Shi, Jie. "Ion transport in polymer electrolytes". Thesis, University of St Andrews, 1993. http://hdl.handle.net/10023/15522.
Testo completoAbstract (sommario):
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.
18
Lu, Xiaopeng [Verfasser]. "Plasma Electrolytic Oxidation (PEO) Coatings on a Mg Alloy from Particle Containing Electrolytes / Xiaopeng Lu". Kiel : Universitätsbibliothek Kiel, 2017. http://d-nb.info/1128149206/34.
Testo completo
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Ralph, James Michael. "A study of doped ceria electrolytes". Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/7782.
Testo completo
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Lee, Ming Ripman, e 李明. "Monte Carlo simulation for confined electrolytes". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31240513.
Testo completo
21
Al-Mudaris, A. A. M. "Ionic transport in model polymer electrolytes". Thesis, University of Kent, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235984.
Testo completo
22
Inkster, Rachel T. "Liquid crystalline side chain polymer electrolytes". Thesis, University of Aberdeen, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419840.
Testo completoAbstract (sommario):
Ion transport in polymer electrolytes is, in general, strongly coupled to the segmental motions of the host polymer. Thus, ionic conductivity is not usually observed below the glass transition. Recent research has highlighted examples of polymer electrolytes in which the ionic conductivity is not coupled to the polymeric motions. This thesis investigates one such group of polymers: namely, liquid-crystalline side-chain polymers. The aim is to investigate the effect of different liquid crystal morphologies and to gain insight into the ion transport mechanism. The thermal, mechanical and electrical properties of three different liquid-crystalline side-chain polymer electrolytes have been investigated. These included calamitic and discotic phases, with clearing temperatures in the range 53-95°C. This study shows a general behaviour characteristics of a range of such systems. After passing through the clearing transition into the liquid crystalline phase, the conductivity falls away more slowly as the glass transition is approached. Conductivities at the clearing temperatures are typically 10-7 S cm-1. The conductivities of selected complexes are examined under variable pressure (0-160 MPa), and activation volumes, typically in the range 20-40 cm3 mol-1, are obtained. Plots of EA versus VA reveal that the conductivity behaviour deviates from the PEO mechanism to varying degrees. Generally, introducing liquid crystalline side chains introduces more free volume into the system, and hence lowers the activation volumes. This new result supports an earlier proposal that the liquid crystalline phase opens up and stabilises the ethylene oxide structure, trapping in free volume, which is retained in the system as the glass transition is approached. Ion transport, however, remains dependent on local motions of the polymer. Optimisation of electrolyte properties depends on careful choice of system parameters (salt concentration, polymer morphology, etc).
23
Sahota, Tarsem Singh. "Polymer electrolytes for iontophoretic drug delivery". Thesis, De Montfort University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391690.
Testo completo
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Modiba, Portia. "Electrolytes for redox flow battery systems". Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/3999.
Testo completoAbstract (sommario):
Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2010.Electrochemical behaviour of Ce, Fe, Cr,V and Mn in the presence of DTPA, EDTA, EDDS, NTA ligands were investigated by using cyclic voltammetry, a rotating disc electrode and electrochemical impedance spectroscopy for use in redox flow battery (RFB) systems. RFB is currently used for energy storage, the vanadium, which is used in most of the RFB’s, however suffers from species crossover and sluggish reactions, which limit the lifetime of the battery. These various ligands and metal complexes mentioned above where all examined to identify the suitable and favoured electrolyte that can be used for a RFB system. Kinetic parameters such as potential, limiting current, transfer coefficient, diffusion coefficients, and rate constants were studied. RDE experiments confirmed that the parameters measured by CV are similar under hydrodynamic conditions and can be used to determine the kinetic parameters of the redox couples. The use of DTPA as a ligand for complexation of Ce(IV) gave more favourable results compared to other ligand with various metal complexes used in this study [1-3]. The results of kinetic studies of Ce(IV)–DTPA complex shows promise as an electrolyte for a redox flow battery. The separation of V(IV)/(V), Fe (III)/(IV),Cr(III)/(IV),Mn (III)/(IV) and Ce(III)/(IV) with various ligands (EDTA, EDDS, NTA and DTPA) were also investigated using capillary electrophoresis. To understand the speciation of these metal complexes as used in this study and particularly the vanadium, for the reason that it has a complicated (V) oxidation state. The charge/discharge performance of all electrolytes used in this work was determined and a high voltage achieved when Ce-DTPA was used, and it is compared to that of the vanadium electrolyte currently in use. This was evaluated with systems studied previously. Therefore, Ce-DTPA will be a suitable electrolyte for redox flow battery systems.
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Ainsworth, David A. "Crystalline polymer and small molecule electrolytes". Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/2156.
Testo completoAbstract (sommario):
The research presented in this thesis includes a detailed investigation into factors influencing ionic conductivity in the crystalline polymer electrolyte PEO₆:LiPF₆. It has previously been shown that preparing PEO₆:LiPF₆ with PEO modified with larger –OC₂H₅ end groups increases ionic conductivity by one order of magnitude [¹],primarily due to disruption of the crystal structure caused by the inclusion of the larger end groups. In this study it is shown that by reducing PEO molecular weight in crystalline PEO₆:LiPF₆ ionic conductivity is also increased. This was attributed to an increasing concentration of polymer chain end regions upon lowering molecular weight resulting in the creation of more defects, as well as possible increases in crystallite size resulting in longer continuous pathways for ion transport. Similar results were observed using both polydispersed and monodispersed PEO to prepare complexes. In addition, it is demonstrated here that ionic conductivity in crystalline polymerelectrolytes is not confined to PEO₆:LiXF₆ (X=P, As, Sb)[²][³] type materials. The structures and ionic conductivity data are reported for a series of new crystalline polymer complexes: the alkali metal electrolytes. They are composed of low molecular weight PEO and different alkali metal hexafluoro salts (Na⁺, K⁺ and Rb⁺), and include the best conductor poly(ethylene oxide)₈:NaAsF₆ discovered to date [⁴], with a conductivity 1.5 orders of magnitude higher than poly(ethylene oxide)₆:LiAsF₆. A new class of solid ion conductor is reported: the crystalline small-molecule electrolytes. Such materials consist of lithium salts dissolved in low molecular weight glyme molecules [CH₃O(CH₂CH₂O)[subscript(n)]CH₃, n=1-12], forming crystalline complexes [⁵][⁶]. These materials are soft solids unlike ceramic electrolytes and unlike polymer electrolytes they are highly crystalline, are of low molecular weight and have no polydispersity. By varying the number of repeat units in the glyme molecule, many complexes may be prepared with a wide variety of structures. Here, ionic conductivity and cation transference number (t₊) data for several such complexes is presented [⁷][⁸][⁹].These complexes have appreciable ionic conductivities for crystalline complexes and their t₊ values vary markedly depending on the glyme molecule utilized. The differences in t₊ values can be directly attributed to differences in their crystal structures. [¹] Staunton, E., Andreev, Y.G. & Bruce, P.G. Factors influencing the conductivity of crystalline polymer electrolytes. Faraday Discussions 134, 143-156 (2007). [²] Gadjourova, Z., Andreev, Y.G., Tunstall, D.P. & Bruce, P.G. Ionic conductivity in crystalline polymer electrolytes. Nature 412, 6846 (2001). [³] Stoeva, Z., Martin-Litas, I., Staunton, I., Andreev, Y.G. & Bruce, B.G. Ionic Conductivity in the Crystalline Polymer Electrolytes PEO₆:LiXF₆, X = P, As, Sb. J. Am. Chem. Soc. 125, 4619-4626(2003). [⁴] Zhang, C., Gamble, S., Ainsworth, D., Slawin, A.M.Z., Andreev, Y.G. & Bruce, P.G. Alkali metal crystalline polymer electrolytes. Nature Materials 8, 580-584 (2009). [⁵] Henderson, W.A., Brooks, N.R., Brennessel, W.W. & Young Jr, V.G. Triglyme-Li⁺ Cation Solvate Structures: Models for Amorphous Concentrated Liquid and Polymer Electrolytes (I). Chem. Mater. 15, 4679-4684 (2003). [⁶] Henderson, W.A., Brooks, N.R. & Young Jr, V.G. Tetraglyme-Li⁺ Cation Solvate Structures: Models for Amorphous Concentrated Liquid and Polymer Electrolytes (II). Chem. Mater. 15, 4685-4690 (2003). [⁷] Zhang, C., Andreev, Y.G. & Bruce, P.G. Crystalline small-molecule electrolytes. Angewandte Chemie, International Edition 46, 2848-2850 (2007). [⁸] Zhang, C., Ainsworth, D., Andreev, Y.G. & Bruce, P.G. Ionic Conductivity in the Solid Glyme Complexes [CH₃O(CH₂CH₂O)[subscript(n)]CH₃]:LiAsF₆ (n = 3,4). J. Am. Chem. Soc. 129, 8700- 8701 (2007). [⁹] Zhang, C., Lilley, S.J., Ainsworth, D., Staunton, E., Andreev, Y.G., Slawin, A.M.Z. & Bruce, P.G. Structure and Conductivity of Small-Molecule Electrolytes [CH₃O(CH₂CH₂O)[subscript(n)]CH₃]:LiAsF₆ (n = 8-12). Chem. Mater. 20, 4039-4044 (2008).
26
YANG, YONGRUI. "Flexible Supercapacitors with Novel Gel Electrolytes". University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1590682495188219.
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Sylla, Salime. "Electrolytes polymères à conduction unipolaire cationique". Grenoble INPG, 1992. http://www.theses.fr/1992INPG0021.
Testo completoAbstract (sommario):
Un nouveau sel de lithium a anion perfluorosulfonate a ete prepare et caracterise au cours de cette etude. Les analyses electrochimiques de complexes prepares par dissolution de ce sel dans des homo et copolymeres d'oxyde d'ethylene ont permis de s'assurer que ceux-ci presentaient des conductivites legerement superieures a celles des complexes prepares avec des perchlorate et triflate de lithium et une bonne stabilite electrochimique. Ce sel presentant de surcroit des insaturations a ete copolymerise avec un macronomere, conduisant a des copolymeres lineaires, et avec les doubles liaisons allyliques pendantes d'un polyoxyde d'ethylene modifie pour preparer des reseaux. Les copolymerisations permettent ainsi d'immobiliser l'anion par des liens covalents stables et d'obtenir des electrolytes polymeres a transport exclusivement cationique, resultats confirmes par la rmn a gradient de champ pulse. Des conductivites de 10##5 s/cm peuvent etre obtenues lorsque le sel est immobilise au sein d'un reseau ce qui rend ce systeme potentiellement utilisable dans les generateurs au lithium soit seul, soit avec une quantite tres faible de sel libre puisque l'appauvrissement en sel de certaines zones, consecutif au gradient de concentration, ne devrait plus se produire. Les caracteristiques electrochimiques des interfaces de ces electrolytes avec l'electrode de lithium et le materiau d'insertion tis#2 ont ete realisees par spectroscopie d'impedance et l'etude electrochimique du depot de lithium a ete effectuee par voltametrie cyclique sur microelectrodes. Outre ces travaux sur les electrolytes polymeres a transport unipolaire, une etude approfondie du comportement des complexes obtenus en dissolvant un nouveau sel le bis(trifluorosulfonyl) imidure de lithium-litfsi dans plusieurs polymeres solvatants: poe, copolymeres lineaires et reticules d'oxyde d'ethylene a ete realisee. Les melanges a tres faible concentration de litfsi et des electrolytes unipolaires presentent des conductivites de 10##4 s/cm a la temperature de fonctionnement des batteries
28
Harvie, James L. "The electrochemistry of liquid polymer electrolytes". Thesis, University of Aberdeen, 1988. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU020268.
Testo completoAbstract (sommario):
This thesis is concerned with ion-ion and ion-polymer interactions in liquid polymer electrolytes (LPE's). LPE's are useful analogues of visco-elastic polymer electrolytes (VEPE's) which might be used in high energy density batteries. The LPE's investigated comprise alkali metal salts dissolved in polyethers. Two types of polyether are studied, liquid copolymers of ethylene oxide (EO) and propylene oxide (PO), and poly(propylene oxide) (PPO). Separation of an EO-rich phase at low temperature or,for some iodide salt solutions, precipitation of the salt at high temperature, are two phenomena found to limit the temperature range in which some LPE's remain homogeneous. A new parameter, the diffusion number, is defined to reflect the relative diffusional mobilities of the cation and anion ion-constituents. This parameter is influenced by the motion of neutral ion aggregates (e.g. ion-pairs) and is thus fundamentally different from classical transference numbers, which indicate the net ion-constituent migration during electrolysis in the absence of diffusion. Cation transference numbers (t+) are measured using the Hittorf method. The results, showing t+ = 0.05 (+0.05), suggest that the cation is almost immobile during electrolysis and are significantly different from the results of experiments intended to determine transference numbers in VEPE's. The discrepancy is explained in terms of a model which stresses the importance of the non-conductive motion of neutral ion-pairs in polymer electrolytes. Non-conductive motion is demonstrated by diffusion coefficients determined by pulsed magnetic field gradient nuclear magnetic resonance. Studies of the conductivity and viscosity of LPE's demonstrate the influence of the cation and the polymer on the degree of dissociation of the dissolved salt. The conductivity of PPO-based electrolytes is shown to display a very large end-group effect. The mobility of the dissociated ions is found to be dependent on the anion and the nature of the polymer back-bone.
29
Lee, Ming Ripman. "Monte Carlo simulation for confined electrolytes /". Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22055009.
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Almeida, Carlos Manuel Rodrigues de. "Optimization of Li-ion solid electrolytes". Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/15803.
Testo completoAbstract (sommario):
Mestrado em Sistemas Energéticos SustentáveisThe synthesis and optimization of two Li-ion solid electrolytes were studied in this work. Different combinations of precursors were used to prepare La0.5Li0.5TiO3 via mechanosynthesis. Despite the ability to form a perovskite phase by the mechanochemical reaction it was not possible to obtain a pure La0.5Li0.5TiO3 phase by this process. Of all the seven combinations of precursors and conditions tested, the one where La2O3, Li2CO3 and TiO2 were milled for 480min (LaOLiCO-480) showed the best results, with trace impurity phases still being observed. The main impurity phase was that of La2O3 after mechanosynthesis (22.84%) and Li2TiO3 after calcination (4.20%). Two different sol-gel methods were used to substitute boron on the Zr-site of Li1+xZr2-xBx(PO4)3 or the P-site of Li1+6xZr2(P1-xBxO4)3, with the doping being achieved on the Zr-site using a method adapted from Alamo et al (1989). The results show that the Zr-site is the preferential mechanism for B doping of LiZr2(PO4)3 and not the P-site. Rietveld refinement of the unit-cell parameters was performed and it was verified by consideration of Vegard’s law that it is possible to obtain phase purity up to x = 0.05. This corresponds with the phases present in the XRD data, that showed the additional presence of the low temperature (monoclinic) phase for the powder sintered at 1200ºC for 12h of compositions with x ≥ 0.075. The compositions inside the solid solution undergo the phase transition from triclinic (PDF#01-074-2562) to rhombohedral (PDF#01-070-6734) when heating from 25 to 100ºC, as reported in the literature for the base composition. Despite several efforts, it was not possible to obtain dense pellets and with physical integrity after sintering, requiring further work in order to obtain dense pellets for the electrochemical characterisation of Li Zr2(PO4)3 and Li1.05Zr1.95B0.05(PO4)3.
A síntese e otimização das propriedades de dois eletrólitos sólidos, condutores de iões de lítio, foram estudadas neste trabalho. Várias combinações de precursores foram usadas para preparar La0.5Li0.5TiO3 através de mecanosíntese. Apesar da obtenção duma fase perovskite, através da reação mecanoquímica, não foi possível obter uma fase pura de La0.5Li0.5TiO3 por via deste processo. De todas as sete combinações de precursores e condições, que foram testadas, aquela em que se moeram La2O3, Li2CO3 e TiO2 ao longo de 480min (LaOLiCO-480) foi a que apresentou melhores resultados. As principais fases das impurezas foram La2O3 após a mecanosíntese (22.84%) e Li2TiO3 após a calcinação (4.20%). Dois métodos de síntese sol-gel foram utilizados para dopar LiZr2(PO4)3 com boro no lugar do zircónio, Li1+xZr2-xBx(PO4)3, ou no lugar do fósforo, Li1+6xZr2(P1-xBxO4)3; com a dopagem a ser alcançada no lugar do Zr utilizando um método adaptado de Alamo et al (1989). Os resultados mostram que a substituição no lugar do Zr é o mecanismo preferencial na dopagem de LiZr2(PO4)3 com B e não no lugar do P. Foi efetuado o refinamento Rietveld dos parâmetros da célula unitária, tendo sido verificado pela aplicação da lei de Vegard que é possível obter uma fase pura até x = 0.05. Esta verificação está de acordo com as fases presentes nos dados de DRX, que mostram a presença adicional da fase de baixa temperatura (monoclínica) para os pós sinterizados a 1200ºC durante 12h, para as composições com x ≥ 0.075. As composições, dentro do limite de solubilidade sólida, apresentam uma transição da fase triclínica (PDF#01-074-2562) para romboédrica (PDF#01-070-6734) quando aquecidas de 25 para 100ºC, tal como indicado na bibliografia consultada para a composição base. Apesar de vários esforços, não foi possível obter pastilhas bem densificadas e integras após o ciclo de sinterização, sendo necessário trabalho adicional para conseguir obter pastilhas densas para posterior caracterização eletroquímica das composições Li Zr2(PO4)3 e Li1.05Zr1.95B0.05(PO4)3.
31
Soares, Helena Sofia Marques Pinto. "Electrolytes for ceramic oxide fuel cells". Doctoral thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15883.
Testo completoAbstract (sommario):
Doutoramento em Nanociências e NanotecnologiaThe main objective of this dissertation is the development and processing of novel ionic conducting ceramic materials for use as electrolytes in proton or oxide-ion conducting solid oxide fuel cells. The research aims to develop new processing routes and/or materials offering superior electrochemical behavior, based on nanometric ceramic oxide powders prepared by mechanochemical processes. Protonic ceramic fuel cells (PCFCs) require electrolyte materials with high proton conductivity at intermediate temperatures, 500-700ºC, such as reported for perovskite zirconate oxides containing alkaline earth metal cations. In the current work, BaZrO3 containing 15 mol% of Y (BZY) was chosen as the base material for further study. Despite offering high bulk proton conductivity the widespread application of this material is limited by its poor sinterability and grain growth. Thus, minor additions of oxides of zinc, phosphorous and boron were studied as possible sintering additives. The introduction of ZnO can produce substantially enhanced densification, compared to the un-doped material, lowering the sintering temperature from 1600ºC to 1300ºC. Thus, the current work discusses the best solid solution mechanism to accommodate this sintering additive. Maximum proton conductivity was shown to be obtained in materials where the Zn additive is intentionally adopted into the base perovskite composition. P2O5 additions were shown to be less effective as a sintering additive. The presence of P2O5 was shown to impair grain growth, despite improving densification of BZY for intermediate concentrations in the range 4 – 8 mol%. Interreaction of BZY with P was also shown to have a highly detrimental effect on its electrical transport properties, decreasing both bulk and grain boundary conductivities. The densification behavior of H3BO3 added BaZrO3 (BZO) shows boron to be a very effective sintering aid. Nonetheless, in the yttrium containing analogue, BaZr0.85Y0.15O3- (BZY) the densification behavior with boron additives was shown to be less successful, yielding impaired levels of densification compared to the plain BZY. This phenomenon was shown to be related to the undesirable formation of barium borate compositions of high melting temperatures. In the last section of the work, the emerging oxide-ion conducting materials, (Ba,Sr)GeO3 doped with K, were studied. Work assessed if these materials could be formed by mechanochemical process and the role of the ionic radius of the alkaline earth metal cation on the crystallographic structure, compositional homogeneity and ionic transport. An abrupt jump in oxide-ion conductivity was shown on increasing operation temperature in both the Sr and Ba analogues.
O principal objetivo deste trabalho é o desenvolvimento e processamento de novos materiais cerâmicos protónicos e iónicos para utilizar como eletrólito das células de combustível de óxidos sólidos (PCFCs e SOFCs, respetivamente). Com este estudo pretende-se, então, desenvolver novas formas de processamento e/ou materiais que apresentem características eletroquímicas atrativas, à base de óxidos cerâmicos nanométricos de pós preparados por processos mecanoquímicos. Existem alguns requisitos que devem ser tidos em conta de forma a garantir a máxima eficiência das PCFCs, destacando-se a elevada condutividade protónica do eletrólito aquando da operação numa gama de temperaturas intermédias, 500-700ºC. Os materiais do tipo “perovskite” foram apresentados como potenciais candidatos a incorporar o eletrólito das PCFCs, sendo o BaZrO3 dopado com 15 mol% de ítrio (BZY) o material base escolhido neste trabalho. Apesar da sua conhecida elevada condutividade protónica, estes materiais apresentam algumas limitações, tais como a fraca sinterabilidade e crescimento de grão. De forma a ultrapassar esta dificuldade, foram adicionadas pequenas quantidades de óxidos de zinco, fósforo e boro que foram estudados como possíveis aditivos de sinterização. A adição de ZnO mostrou melhorias significativas na densificação quando comparado com o material não modificado (BZY), permitindo ainda reduzir a temperatura de sinterização de 1600ºC para 1300ºC. Neste trabalho estudou-se, também, qual o melhor mecanismo de solução sólida para a adição deste aditivo, tendo-se obtido a máxima condutividade protónica nos materiais em que o Zn é intencionalmente introduzido na composição de base de “perovskite”. O P2O5 mostrou ser menos efetivo como aditivo de sinterização. A sua presença foi bastante prejudicial no crescimento de grão, apesar dos elevados níveis de densificação obtidos quando adicionado em quantidades entre 4 e 8 mol%. Porém, a utilização de fósforo mostrou também ser dramática no transporte elétrico, diminuindo a condutividade não só no interior do grão (“bulk”) como nas suas fronteiras. Já a adição de H3BO3 ao BaZrO3 (BZO) mostrou-se muito efetiva para a sinterização deste componente. Contudo, quando adicionado ao sistema dopado com ítria (BaZr0.85Y0.15O3-, BZY), o comportamento é diferente, produzindo níveis deficientes de densificação quando comparado com o BZY puro. Este fenómeno ocorre devido à formação de fases secundárias de borato de bário, cujas temperaturas de fusão são bastante elevadas. Na última parte deste trabalho foi estudado um novo material com condutividade iónica de iões óxido, o (Ba,Sr)GeO3 dopado com K. Neste estudo pretendia-se, não só avaliar a possibilidade de preparar estes pós com recurso a processos mecanoquímicos, como também estudar o papel da variação do raio iónico do catião metálico alcalino-terroso no transporte iónico, homogeneidade composicional e estrutura cristalina. Verificou-se que este material apresenta uma alteração significativa na condutividade iónica com o aumento da temperatura de operação em ambas as composições (Ba e Sr).
32
Webster, Mark Ian. "Molecular motion in polymer electrolytes : an investigation of methods for improving the conductivity of solid polymer electrolytes". Thesis, University of Kent, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269150.
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33
zhang, peilun. "Zn Corrosion in Alkaline Aqueous Electrolytes: Effect of Electrolyte Composition on Corrosion Rate and Inhibitors to Suppress Corrosion". Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1618400150411797.
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34
Gamstedt, Heléne. "Ionic Liquid Electrolytes for Photoelectrochemical Solar Cells". Doctoral thesis, KTH, Chemistry, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-426.
Testo completoAbstract (sommario):
Potential electrolytes for dye-sensitized photoelectrochemical solar cells have been synthesized and their applicability has been investigated. Different experimental techniques were used in order to characterize the synthesized electrolytes, such as elemental analysis, electrospray ionisation/mass spectrometry, cyclic voltammetry, dynamic viscosity measurements, as well as impedance, Raman and NMR spectroscopy. Some crystal structures were characterized by using single crystal X-ray diffraction.
In order to verify the eligibility of the ionic compounds as electrolytes for photoelectrochemical solar cells, photocurrent density/photovoltage and incident photon-to-current conversion efficiency measurements were performed, using different kinds of light sources as solar simulators. In electron kinetic studies, the electron transport times in the solar cells were investigated by using intensitymodulated photocurrent and photovoltage spectroscopy. The accumulated charge present in the semiconductor was studied in photocurrent transient measurements.
The ionic liquids were successfully used as solar cell electrolytes, especially those originating from the diethyl and dibutyl-alkylsulphonium iodides. The highest overall conversion efficiency of almost 4 % was achieved by a dye-sensitized, nanocrystalline solar cell using (Bu2MeS)I:I2 (100:1) as electrolyte (Air Mass 1.5 spectrum at 100 W m-2), quite compatible with the standard efficiencies provided by organic solvent-containing cells. Several solar cells with iodine-doped metal-iodidebased electrolytes reached stable efficiencies over 2 %. The (Bu2MeS)I:I2-containing cells showed better long-term stabilities than the organic solvent-based cells, and provided the fastest electron transports as well as the highest charge accumulation.
Several polypyridyl-ruthenium complexes were tested as solar cell sensitizers. No general improvements could be observed according to the addition of amphiphilic co-adsorbents to the dyes or nanopartices of titanium dioxide to the electrolytes. For ionic liquid-containing solar cells, a saturation phenomena in the short-circuit current densities emerged at increased light intensities, probably due to inherent material transport limitation within the systems.
Some iodoargentates and -cuprates were structurally characterized, consisting of monomeric or polymeric entities with anionic networks or layers. A system of metal iodide crownether complexes were employed and tested as electrolytes in photoelectrochemical solar cells, though with poorer results. Also, the crystal structure of a copper-iodide-(12-crown-4) complex has been characterized
35
Sivertsen, Edvard. "Membrane Separation of Anions in Concentrated Electrolytes". Doctoral thesis, Norwegian University of Science and Technology, Department of Chemical Engineering, 2001. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2100.
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36
Liivat, Anti. "Ordering in Crystalline Short-Chain Polymer Electrolytes". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7853.
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Gamstedt, Heléne. "Ionic liquid electrolytes for photoelectrochemical solar cells /". Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-426.
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38
Brandell, Daniel. "Understanding Ionic Conductivity in Crystalline Polymer Electrolytes". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5734.
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39
Flake, John Christopher. "Photoelectrochemical etching of silicon in nonaqeous electrolytes". Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/13278.
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40
Bayrak, Pehlivan İlknur. "Functionalization of polymer electrolytes for electrochromic windows". Doctoral thesis, Uppsala universitet, Fasta tillståndets fysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-204437.
Testo completoAbstract (sommario):
Saving energy in buildings is of great importance because about 30 to 40 % of the energy in the world is used in buildings. An electrochromic window (ECW), which makes it possible to regulate the inflow of visible light and solar energy into buildings, is a promising technology providing a reduction in energy consumption in buildings along with indoor comfort. A polymer electrolyte is positioned at the center of multi-layer structure of an ECW and plays a significant role in the working of the ECW. In this study, polyethyleneimine: lithium (bis(trifluoromethane)sulfonimide (PEI:LiTFSI)-based polymer electrolytes were characterized by using dielectric/impedance spectroscopy, differential scanning calorimetry, viscosity recording, optical spectroscopy, and electrochromic measurements. In the first part of the study, PEI:LiTFSI electrolytes were characterized at various salt concentrations and temperatures. Temperature dependence of viscosity and ionic conductivity of the electrolytes followed Arrhenius behavior. The viscosity was modeled by the Bingham plastic equation. Molar conductivity, glass transition temperature, viscosity, Walden product, and iso-viscosity conductivity analysis showed effects of segmental flexibility, ion pairs, and mobility on the conductivity. A connection between ionic conductivity and ion-pair relaxation was seen by means of (i) the Barton-Nakajima-Namikawa relation, (ii) activation energies of the bulk relaxation, and ionic conduction and (iii) comparing two equivalent circuit models, containing different types of Havriliak-Negami elements, for the bulk response. In the second part, nanocomposite PEI:LiTFSI electrolytes with SiO2, In2O3, and In2O3:Sn (ITO) were examined. Adding SiO2 to the PEI:LiTFSI enhanced the ionic conductivity by an order of magnitude without any degradation of the optical properties. The effect of segmental flexibility and free ion concentration on the conduction in the presence of SiO2 is discussed. The PEI:LiTFSI:ITO electrolytes had high haze-free luminous transmittance and strong near-infrared absorption without diminished ionic conductivity. Ionic conductivity and optical clarity did not deteriorate for the PEI:LiTFSI:In2O3 and the PEI:LiTFSI:SiO2:ITO electrolytes. Finally, propylene carbonate (PC) and ethylene carbonate (EC) were added to PEI:LiTFSI in order to perform electrochromic measurements. ITO and SiO2 were added to the PEI:LiTFSI:PC:EC and to a proprietary electrolyte. The nanocomposite electrolytes were tested for ECWs with the configuration of the ECWs being plastic/ITO/WO3/polymer electrolyte/NiO (or IrO2)/ITO/plastic. It was seen that adding nanoparticles to polymer electrolytes can improve the coloring/bleaching dynamics of the ECWs. From this study, we show that nanocomposite polymer electrolytes can add new functionalities as well as enhancement in ECW applications.
41
Macklin, W. J. "Lithium insertion electrodes and molten salt electrolytes". Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235017.
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42
莫家麟 e Ka-lun Mok. "Movement of electrolytes in a charged capillary". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31213443.
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43
Bloomer, S. T. "Stress-strain behaviour of soils containing electrolytes". Thesis, University of Sunderland, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381589.
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44
Young, Kevin Edward. "Ionic conductivity in silicate - containing solid electrolytes". Thesis, University of Exeter, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335654.
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45
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.
Testo completoAbstract (sommario):
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.
46
Abu-Lebdeh, Yaser. "Proton conducting polymer electrolytes for CO sensors". Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342627.
Testo completo
47
Neat, R. J. "Preparation-related effects in polymer solid electrolytes". Thesis, De Montfort University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383257.
Testo completo
48
Chaudoy, Victor. "Electrolytes polymères gélifiés pour microbatteries au lithium". Thesis, Tours, 2016. http://www.theses.fr/2016TOUR4019/document.
Testo completoAbstract (sommario):
Au cours de cette thèse, un nouvel électrolyte polymère gel pour la réalisation de microbatteries au lithium a été développé. Le gel a été préparé par « confinement » d’une phase de N-propyl-N-méthylpyrrolidinium bis(fluorosulfonyl)imide (P13FSI) et de LiTFSI dans un réseau semi-interpénétré (sRip) de polymère (PVdFHFP/ réseau de POE). L’électrolyte gel a tout d’abord été optimisé et étudié en termes de propriétés physicochimiques et de transport ionique en fonction de sa composition. Ensuite, des batteries Li/LiNi1/3Mn1/3Co1/3O2 ont été assemblées en utilisant l’électrolyte sRip. Les performances ont par ailleurs été comparées aux systèmes de références utilisant l’électrolyte à base de POE ou de PVdF-HFP. Outre ses propriétés améliorées par rapport au PVdF-HFP et au réseau de POE (propriétés mécaniques, confinement), l’électrolyte sRip est compatible avec le procédé de dépôt de l’électrode négative en lithium par évaporation sous vide. L’électrolyte sRip optimisé a donc été utilisé pour fabriquer une nouvelle génération de microbatteries en s’affranchissant de l’électrolyte céramique, le LiPON, afin d’abaisser la résistance interne. Les microbatteries Li/sRip gel/LiCoO2 délivrent une capacité nominale stable de 850 μAh à C sur 100 cycles à 25°CIn this thesis, a new polymer gel electrolyte was prepared and optimized for Li based microbatteries. The gel consisted of an ionic liquid based phase (P13FSI/LiTFSI) confined in a semi-interpenetrating polymers (sIPN) network (PVdF-HFP/crosslinked PEO). sIPN electrolytes were prepared and optimized according to the PVdFHFP/ crosslinked PEO ratio and the liquid phase fraction. Furthermore, the sIPN electrolyte was used as an electrolyte in Li/LiNi1/3Mn1/3Co1/3O2 battery. The performances of the battery (specific capacity, efficiency, cyclability) were determined and compared to batteries using a crosslinked PEO or PVdF-HFP based gel. Such a thin and stable sIPN electrolyte film enabled the preparation of Li based microbatteries using thermal evaporation deposition of lithium directly conducted on the sIPN electrolyte film. This assembly (Li/sIPN) was therefore used to prepare a LiCoO2/sIPN gel/Li quasi solid-state microbattery. This microbattery showed a stable nominal capacity of 850 μAh for over 100 cycles of charge and discharge under 1 C rate at 25°C
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Richards, William D. (William Davidson). "Ab-initio simulation of novel solid electrolytes". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/88398.
Testo completoAbstract (sommario):
Thesis: S.M., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2014.30
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 41-43).
All solid-state batteries may be a solution to some of the problems facing conventional organic electrolytes in Li and Na-ion batteries, but typically conductivities are very low. Reports of fast lithium conduction in Li 0GeP 2S1 2 (LGPS), with conductivity of 12 mS/cm at room temperature, have shown that Li -diffusion in solid electrolytes can match or exceed the liquid electrolytes in use today. I report results of ab-initio calculations on a related system of materials, Nai0 MP 2SI 2 (M = Ge, Si, Sn), which are predicted to have similar properties to LGPS as candidates for electrolytes in Na-ion batteries. I also derive methods to estimate the error associated with diffusion simulations, so that appropriate tradeoffs between computational time and simulation accuracy can be made. This is a key enabler of a high throughput computational search for new electrolyte materials.
by William D. Richards.
S.M.
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Gray, David John. "Conductivity studies of selected anionic composite electrolytes". Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47453.
Testo completo